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83850691
10.1007/s00033-018-0924-y
We establish the existence of saddle points for a free boundary problem describing the two-dimensional free surface of a ferrofluid which undergoes normal field instability (also known as Rosensweig instability). The starting point consists in the ferro-hydrostatic equations for the magnetic potentials in the ferrofluid and air, and the function describing their interface. The former constitute the strong form for the Euler-Lagrange equations of a convex-concave functional. We extend this functional in order to include interfaces that are not necessarily graphs of functions. Saddle points are then found by iterating the direct method of the calculus of variations and by applying classical results of convex analysis. For the existence part we assume a general (arbitrary) non linear magnetization law. We also treat the case of a linear law: we show, via convex duality arguments, that the saddle point is a constrained minimizer of the relevant energy functional of the physical problem
A free boundary approach to the Rosensweig instability of ferrofluids
a free boundary approach to the rosensweig instability of ferrofluids
establish saddle describing ferrofluid undergoes instability rosensweig instability ferro hydrostatic potentials ferrofluid describing interface. former constitute euler lagrange convex concave functional. extend interfaces necessarily functions. saddle iterating calculus convex analysis. magnetization law. treat convex duality arguments saddle constrained minimizer
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86418951
10.1007/s00033-018-0926-9
This paper concerns the dynamics of a layer of incompressible viscous fluid lying above a rigid plane and with an upper boundary given by a free surface. The fluid is subject to a constant external force with a horizontal component, which arises in modeling the motion of such a fluid down an inclined plane, after a coordinate change. We consider the problem both with and without surface tension for horizontally periodic flows. This problem gives rise to shear-flow equilibrium solutions, and the main thrust of this paper is to study the asymptotic stability of the equilibria in certain parameter regimes. We prove that there exists a parameter regime in which sufficiently small perturbations of the equilibrium at time $t=0$ give rise to global-in-time solutions that return to equilibrium exponentially in the case with surface tension and almost exponentially in the case without surface tension. We also establish a vanishing surface tension limit, which connects the solutions with and without surface tension.Comment: 33 page
Asymptotic stability of shear-flow solutions to incompressible viscous free boundary problems with and without surface tension
asymptotic stability of shear-flow solutions to incompressible viscous free boundary problems with and without surface tension
concerns incompressible viscous lying rigid surface. arises inclined coordinate change. tension horizontally flows. thrust asymptotic equilibria regimes. sufficiently perturbations return exponentially tension exponentially tension. establish vanishing tension connects
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83839144
10.1007/s00033-018-0932-y
The theory of elastic magnets is formulated under possible diffusion and heat flow governed by Fick's and Fourier's laws in the deformed (Eulerian) configuration, respectively. The concepts of nonlocal nonsimple materials and viscous Cahn-Hilliard equations are used. The formulation of the problem uses Lagrangian (reference) configuration while the transport processes are pulled back. Except the static problem, the demagnetizing energy is ignored and only local non-selfpenetration is considered. The analysis as far as existence of weak solutions of the (thermo)dynamical problem is performed by a careful regularization and approximation by a Galerkin method, suggesting also a numerical strategy. Either ignoring or combining particular aspects, the model has numerous applications as ferro-to-paramagnetic transformation in elastic ferromagnets, diffusion of solvents in polymers possibly accompanied by magnetic effects (magnetic gels), or metal-hydride phase transformation in some intermetalics under diffusion of hydrogen accompanied possibly by magnetic effects (and in particular ferro-to-antiferromagnetic phase transformation), all in the full thermodynamical context under large strains
A thermodynamically consistent model of magneto-elastic materials under diffusion at large strains and its analysis
a thermodynamically consistent model of magneto-elastic materials under diffusion at large strains and its analysis
elastic magnets formulated governed fick fourier laws deformed eulerian respectively. concepts nonlocal nonsimple viscous cahn hilliard used. formulation lagrangian pulled back. demagnetizing ignored selfpenetration considered. thermo careful regularization galerkin strategy. ignoring combining numerous ferro paramagnetic elastic ferromagnets solvents polymers possibly accompanied gels hydride intermetalics accompanied possibly ferro antiferromagnetic thermodynamical
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42707455
10.1007/s00033-018-0933-x
Till date, the sequence of vortices present in the solid corners of steady internal viscous incompressible flows, widely known as Moffatt vortices was thought to be infinite. However, the already existing and most recent geometric theories on incompressible viscous flows that express vortical structures in terms of critical points in bounded domains, indicate a strong opposition to this notion of infiniteness. In this study, we endeavor to bridge the gap between the two opposing stream of thoughts by addressing what might have gone wrong and pinpoint the shortcomings on the assumptions of the existing theorems on Moffatt vortices. We provide our own set of proofs for establishing the finiteness of the sequence of Moffatt vortices by making use of the continuum hypothesis and Kolmogorov scale, which guarantee a non-zero scale for the smallest vortex structure possible in incompressible viscous flows. We point out that the notion of infiniteness resulting from discrete self-similarity of the vortex structures is not physically feasible. The centers of these vortices have been quantified by us as fixed points through Brouwer fixed-point theorem and boundary of a vortex as circle cell. With the aid of these new developments and making use of some existing theorems in topology along with some elementary concept of mathematical analysis, we provide several approaches to delve into this issue. All these approaches converge to the same conclusion that the sequence of Moffatt vortices cannot be infinite; in fact, it is at most finite.Comment: 21 pages, 4 figures. New representation with different title of the previous version of the article "The Finiteness of Moffatt vortices
Moffatt vortices: Concerns and Finiteness
moffatt vortices: concerns and finiteness
till vortices corners steady viscous incompressible flows widely moffatt vortices thought infinite. geometric incompressible viscous flows express vortical opposition notion infiniteness. endeavor bridge opposing stream thoughts addressing gone wrong pinpoint shortcomings assumptions theorems moffatt vortices. proofs establishing finiteness moffatt vortices continuum kolmogorov guarantee smallest vortex incompressible viscous flows. notion infiniteness similarity vortex physically feasible. centers vortices quantified brouwer vortex circle cell. developments theorems topology elementary mathematical delve issue. converge moffatt vortices infinite pages figures. title finiteness moffatt vortices
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93943801
10.1007/s00033-018-0938-5
We prove the existence of weak solutions in the space of energy for a class of non-linear Schroedinger equations in the presence of a external rough magnetic potential. Under our assumptions it is not possible to study the problem by means of usual arguments like resolvent techniques or Fourier integral operators, for example. We use a parabolic regularization and we solve the approximating Cauchy problem. This is achieved by obtaining suitable smoothing estimates for the dissipative evolution. The total mass and energy bounds allow to extend the solution globally in time. We then infer sufficient compactness properties in order to produce a global-in-time finite energy weak solution to our original problem.Comment: Submitted to Zeitschrift f\"ur angewandte Mathematik und Physi
Global, finite energy, weak solutions for the NLS with rough, time-dependent magnetic potentials
global, finite energy, weak solutions for the nls with rough, time-dependent magnetic potentials
schroedinger rough potential. assumptions usual arguments resolvent fourier example. parabolic regularization solve approximating cauchy problem. obtaining smoothing dissipative evolution. bounds extend globally time. infer compactness submitted zeitschrift angewandte mathematik physi
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86418237
10.1007/s00033-018-0948-3
The convergence to equilibrium for renormalised solutions to nonlinear reaction-diffusion systems is studied. The considered reaction-diffusion systems arise from chemical reaction networks with mass action kinetics and satisfy the complex balanced condition. By applying the so-called entropy method, we show that if the system does not have boundary equilibria, then any renormalised solution converges exponentially to the complex balanced equilibrium with a rate, which can be computed explicitly up to a finite dimensional inequality. This inequality is proven via a contradiction argument and thus not explicitly. An explicit method of proof, however, is provided for a specific application modelling a reversible enzyme reaction by exploiting the specific structure of the conservation laws. Our approach is also useful to study the trend to equilibrium for systems possessing boundary equilibria. More precisely, to show the convergence to equilibrium for systems with boundary equilibria, we establish a sufficient condition in terms of a modified finite dimensional inequality along trajectories of the system. By assuming this condition, which roughly means that the system produces too much entropy to stay close to a boundary equilibrium for infinite time, the entropy method shows exponential convergence to equilibrium for renormalised solutions to complex balanced systems with boundary equilibria.Comment: 25 page
Convergence to equilibrium of renormalised solutions to nonlinear chemical reaction-diffusion systems
convergence to equilibrium of renormalised solutions to nonlinear chemical reaction-diffusion systems
renormalised studied. arise kinetics satisfy balanced condition. equilibria renormalised converges exponentially balanced explicitly inequality. inequality proven contradiction argument explicitly. reversible enzyme exploiting conservation laws. possessing equilibria. precisely equilibria establish inequality trajectories system. roughly produces stay infinite exponential renormalised balanced
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129355041
10.1007/s00033-018-0951-8
We consider the complete Euler system describing the time evolution of a general inviscid compressible fluid. We introduce a new concept of measure-valued solution based on the total energy balance and entropy inequality for the physical entropy without any renormalization. This class of so-called dissipative measure-valued solutions is large enough to include the vanishing dissipation limits of the Navier-Stokes-Fourier system. Our main result states that any sequence of weak solutions to the Navier-Stokes-Fourier system with vanishing viscosity and heat conductivity coefficients generates a dissipative measure-valued solution of the Euler system under some physically grounded constitutive relations. Finally, we discuss the same asymptotic limit for the bi-velocity fluid model introduced by H.Brenner
Measure-valued solutions to the complete Euler system revisited
measure-valued solutions to the complete euler system revisited
euler describing inviscid compressible fluid. valued balance inequality renormalization. dissipative valued vanishing dissipation navier stokes fourier system. navier stokes fourier vanishing viscosity conductivity generates dissipative valued euler physically grounded constitutive relations. asymptotic h.brenner
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86420850
10.1007/s00033-018-0955-4
Obtaining reliable numerical simulations of turbulent fluids is a challenging problem in computational fluid mechanics. The Large Eddy Simulations (LES) models are efficient tools to approximate turbulent fluids and an important step in the validation of these models is the ability to reproduce relevant properties of the flow. In this paper we consider a fully discrete approximation of the Navier-Stokes-Voigt model by an implicit Euler algorithm (with respect to the time variable) and a Fourier-Galerkin method (in the space variables). We prove the convergence to weak solutions of the incompressible Navier-Stokes equations satisfying the natural local entropy condition, hence selecting the so-called physically relevant solution
On the convergence of a fully discrete scheme of LES type to physically relevant solutions of the incompressible Navier-Stokes
on the convergence of a fully discrete scheme of les type to physically relevant solutions of the incompressible navier-stokes
obtaining reliable turbulent fluids challenging mechanics. eddy approximate turbulent fluids validation reproduce flow. navier stokes voigt implicit euler fourier galerkin incompressible navier stokes satisfying selecting physically
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93942696
10.1007/s00033-018-0957-2
In this paper, we consider the quasi-neutral limit of a three dimensional Euler-Poisson system of compressible fluids coupled to a magnetic field. We prove that, as Debye length tends to zero, periodic initial-value problems of the model have unique smooth solutions existing in the time interval where the ideal incompressible magnetohydrodynamic equations has smooth solution. Meanwhile, it is proved that smooth solutions converge to solutions of incompressible magnetohydrodynamic equations with a sharp convergence rate in the process of quasi-neutral limit
Quasi-neutral limit of Euler-Poisson system of compressible fluids coupled to a magnetic field
quasi-neutral limit of euler-poisson system of compressible fluids coupled to a magnetic field
quasi neutral euler poisson compressible fluids field. debye tends ideal incompressible magnetohydrodynamic solution. meanwhile proved converge incompressible magnetohydrodynamic sharp quasi neutral
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84330052
10.1007/s00033-018-0961-6
This paper presents a study of the asymptotic behavior of the solutions for the history value problem of a viscoelastic wave equation which features a fading memory term as well as a supercritical source term and a frictional damping term: \begin{align*} \begin{cases} u_{tt}- k(0) \Delta u - \int_0^{\infty} k'(s) \Delta u(t-s) ds +|u_t|^{m-1}u_t =|u|^{p-1}u, \quad \text{ in } \Omega \times (0,T), \\ u(x,t)=u_0(x,t), \quad \text{ in } \Omega \times (-\infty,0], \end{cases} \end{align*} where $\Omega$ is a bounded domain in $\mathbb R^3$ with a Dirichl\'et boundary condition and $u_0$ represents the history value. A suitable notion of a potential well is introduced for the system, and global existence of solutions is justified provided that the history value $u_0$ is taken from a subset of the potential well. Also, uniform energy decay rate is obtained which depends on the relaxation kernel $-k'(s)$ as well as the growth rate of the damping term. This manuscript complements our previous work [Guo et al. in J Differ Equ 257, 3778-3812(2014), J Differ Equ 262, 1956-1979(2017)] where Hadamard well-posedness and the singularity formulation have been studied for the system. It is worth stressing the special features of the model, namely the source term here has a supercritical growth rate and the memory term accounts to the full past history that goes back to $-\infty$
Energy decay of a viscoelastic wave equation with supercritical nonlinearities
energy decay of a viscoelastic wave equation with supercritical nonlinearities
presents asymptotic viscoelastic fading supercritical frictional damping begin align begin delta infty delta quad omega quad omega infty align omega mathbb dirichl value. notion justified well. relaxation kernel damping term. complements hadamard posedness singularity formulation system. worth stressing supercritical accounts goes infty
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93944377
10.1007/s00033-018-0964-3
Kinetic-transport equations that take into account the intra-cellular pathways are now considered as the correct description of bacterial chemotaxis by run and tumble. Recent mathematical studies have shown their interest and their relations to more standard models. Macroscopic equations of Keller-Segel type have been derived using parabolic scaling. Due to the randomness of receptor methylation or intra-cellular chemical reactions, noise occurs in the signaling pathways and affects the tumbling rate. Then, comes the question to understand the role of an internal noise on the behavior of the full population. In this paper we consider a kinetic model for chemotaxis which includes biochemical pathway with noises. We show that under proper scaling and conditions on the tumbling frequency as well as the form of noise, fractional diffusion can arise in the macroscopic limits of the kinetic equation. This gives a new mathematical theory about how long jumps can be due to the internal noise of the bacteria
The fractional diffusion limit of a kinetic model with biochemical pathway
the fractional diffusion limit of a kinetic model with biochemical pathway
intra pathways bacterial chemotaxis tumble. mathematical models. macroscopic keller segel parabolic scaling. randomness methylation intra pathways affects tumbling rate. comes population. chemotaxis biochemical noises. proper tumbling fractional arise macroscopic equation. mathematical jumps bacteria
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129362591
10.1007/s00033-018-0968-z
We are concerned with the global existence and large time behavior of entropy solutions to the one dimensional unipolar hydrodynamic model for semiconductors in the form of Euler-Poisson equations in a bounded interval. In this paper, we first prove the global existence of entropy solution by vanishing viscosity and compensated compactness framework. In particular, the solutions are uniformly bounded with respect to space and time variables by introducing modified Riemann invariants and the theory of invariant region. Based on the uniform estimates of density, we further show that the entropy solution converges to the corresponding unique stationary solution exponentially in time. No any smallness condition is assumed on the initial data and doping profile. Moreover, the novelty in this paper is about the unform bound with respect to time for the weak solutions of the isentropic Euler-Possion system
Large time behavior of entropy solutions to one-dimensional unipolar hydrodynamic model for semiconductor devices
large time behavior of entropy solutions to one-dimensional unipolar hydrodynamic model for semiconductor devices
concerned unipolar hydrodynamic semiconductors euler poisson interval. vanishing viscosity compensated compactness framework. uniformly introducing riemann invariants region. converges stationary exponentially time. smallness doping profile. novelty unform isentropic euler possion
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141533015
10.1007/s00033-018-0969-y
For a nonlinear system of coupled PDEs, that describes evolution of a viscous thin liquid sheet and takes account of surface tension at the free surface, we show exponential $(H^1,\,L^2)$ asymptotic decay to the flat profile of its solutions considered with general initial data. Additionally, by transforming the system to Lagrangian coordinates we show that the minimal thickness of the sheet stays positive for all times. This result proves the conjecture formally accepted in the physical literature [1], that a viscous sheet can not rupture in finite time in absence of external forcing. Moreover, in absence of surface tension we find a special class of initial data for which the Lagrangian solution exhibits $L^2$-exponential decay to the flat profile
Asymptotic decay and non-rupture of viscous sheets
asymptotic decay and non-rupture of viscous sheets
pdes describes viscous sheet tension exponential asymptotic data. additionally transforming lagrangian sheet stays times. proves conjecture formally viscous sheet rupture forcing. tension lagrangian exhibits exponential
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146475479
10.1007/s00033-018-0973-2
In this paper, we present some analytical solutions for the stress fields of nonlinear anisotropic solids with distributed line and point defects. In particular, we determine the stress fields of i) a parallel cylindrically-symmetric distribution of screw dislocations in infinite orthotropic and monoclinic media, ii) a cylindrically-symmetric distribution of parallel wedge disclinations in an infinite orthotropic medium, iii) a distribution of edge dislocations in an orthotropic medium, and iv) a spherically-symmetric distribution of point defects in a transversely isotropic spherical ball
Line and Point Defects in Nonlinear Anisotropic Solids
line and point defects in nonlinear anisotropic solids
anisotropic solids defects. cylindrically screw dislocations infinite orthotropic monoclinic cylindrically wedge disclinations infinite orthotropic dislocations orthotropic spherically defects transversely isotropic spherical ball
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129348146
10.1007/s00033-018-0975-0
We consider a nonlinear Choquard equation $$ -\Delta u+u= (V * |u|^p )|u|^{p-2}u \qquad \text{in }\mathbb{R}^N, $$ when the self-interaction potential $V$ is unbounded from below. Under some assumptions on $V$ and on $p$, covering $p =2$ and $V$ being the one- or two-dimensional Newton kernel, we prove the existence of a nontrivial groundstate solution $u\in H^1 (\mathbb{R}^N)\setminus\{0\}$ by solving a relaxed problem by a constrained minimization and then proving the convergence of the relaxed solutions to a groundstate of the original equation.Comment: 16 page
Groundstates of the Choquard equations with a sign-changing self-interaction potential
groundstates of the choquard equations with a sign-changing self-interaction potential
choquard delta qquad mathbb unbounded below. assumptions covering newton kernel nontrivial groundstate mathbb setminus solving relaxed constrained minimization proving relaxed groundstate
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93946965
10.1007/s00033-018-0979-9
The paper studies the physical-constraints-preserving (PCP) schemes for multi-dimensional special relativistic magnetohydrodynamics with a general equation of state (EOS) on more general meshes. It is an extension of the work [Math. Models Methods Appl. Sci., 27:1871-1928, 2017] which focuses on the ideal EOS and uniform Cartesian meshes. The general EOS without a special expression poses some additional difficulties in discussing the mathematical properties of admissible state set with the physical constraints on the fluid velocity, density and pressure. Rigorous analyses are provided for the PCP property of finite volume or discontinuous Galerkin schemes with the Lax-Friedrichs (LxF) type flux on a general mesh with non-self-intersecting polytopes. Those are built on a more general form of generalized LxF splitting property and a different convex decomposition technique. It is shown in theory that the PCP property is closely connected with a discrete divergence-free condition, which is proposed on the general mesh and milder than that in [Math. Models Methods Appl. Sci., 27:1871-1928, 2017]
On physical-constraints-preserving schemes for special relativistic magnetohydrodynamics with a general equation of state
on physical-constraints-preserving schemes for special relativistic magnetohydrodynamics with a general equation of state
preserving schemes relativistic magnetohydrodynamics meshes. math. sci. focuses ideal cartesian meshes. poses difficulties discussing mathematical admissible pressure. rigorous discontinuous galerkin schemes friedrichs mesh intersecting polytopes. built splitting convex decomposition technique. closely divergence mesh milder math. sci.
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78511830
10.1007/s00033-018-1018-6
We prove local well-posedness for the Cauchy problem associated to Korteweg-de Vries equation on a metric star graph with three semi-infinite edges given by one negative half-line and two positives half-lines attached to a common vertex, for two classes of boundary conditions. The results are obtained in the low regularity setting by using the Duhamel Boundary Forcing Operator, in context of half-lines, introduced by Colliander, Kenig (2002),and extended by Holmer (2006) and Cavalcante (2017).Comment: 24 pages, 1 figure. A final version. Published in Zeitschrift f\"ur angewandte Mathematik und Physi
The Korteweg-de Vries equation on a metric star graph
the korteweg-de vries equation on a metric star graph
posedness cauchy korteweg vries infinite positives attached conditions. regularity duhamel forcing colliander kenig holmer cavalcante .comment pages figure. version. zeitschrift angewandte mathematik physi
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129362151
10.1007/s00033-018-1031-9
The goal of this paper is to investigate the stability of the Helmholtz equation in the high- frequency regime with non-smooth and rapidly oscillating coefficients on bounded domains. Existence and uniqueness of the problem can be proved using the unique continuation principle in Fredholm's alternative. However, this approach does not give directly a coefficient-explicit energy estimate. We present a new theoretical approach for the one-dimensional problem and find that for a new class of coefficients, including coefficients with an arbitrary number of discontinuities, the stability constant (i.e., the norm of the solution operator) is bounded by a term independent of the number of jumps. We emphasize that no periodicity of the coefficients is required. By selecting the wave speed function in a certain \resonant" way, we construct a class of oscillatory configurations, such that the stability constant grows exponentially in the frequency. This shows that our estimates are sharp.Comment: a) Added references, b) rewritten the introduction with a summary of the results/techniques of the paper, c) Corrected typo
Stability estimate for the Helmholtz equation with rapidly jumping coefficients
stability estimate for the helmholtz equation with rapidly jumping coefficients
goal helmholtz rapidly oscillating domains. uniqueness proved continuation fredholm alternative. estimate. discontinuities i.e. norm jumps. emphasize periodicity required. selecting resonant oscillatory configurations grows exponentially frequency. rewritten corrected typo
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8767686
10.1007/s00034-005-2408-5
We have proposed a chaotic cryptographic scheme based on iterating the logistic map and updating the look-up table dynamically. However, it has been broken recently. In this paper, the weaknesses of the original dynamic look-up table scheme are analyzed and a more secure chaotic encryption scheme based on this dynamic look-up table concept is proposed. Theoretical analysis indicates that the modified scheme can resist the reported attacks. Moreover, simulation results show that this encryption scheme leads to a flat ciphertext distribution
A More Secure Chaotic Cryptographic Scheme based on The Dynamic Look-up Table
a more secure chaotic cryptographic scheme based on the dynamic look-up table
chaotic cryptographic iterating logistic updating look dynamically. broken recently. weaknesses look secure chaotic encryption look proposed. resist attacks. encryption ciphertext
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10829346
10.1007/s00034-008-9036-9
The problem of robust constrained model predictive control (MPC) of systems with polytopic uncertainties is considered in this paper. New sufficient conditions for the existence of parameter-dependent Lyapunov functions are proposed in terms of linear matrix inequalities (LMIs), which will reduce the conservativeness resulting from using a single Lyapunov function. At each sampling instant, the corresponding parameter-dependent Lyapunov function is an upper bound for a worst-case objective function, which can be minimized using the LMI convex optimization approach. Based on the solution of optimization at each sampling instant, the corresponding state feedback controller is designed, which can guarantee that the resulting closed-loop system is robustly asymptotically stable. In addition, the feedback controller will meet the specifications for systems with input or output constraints, for all admissible time-varying parameter uncertainties. Numerical examples are presented to demonstrate the effectiveness of the proposed techniques
Robust constrained model predictive control based on parameter-dependent Lyapunov functions
robust constrained model predictive control based on parameter-dependent lyapunov functions
robust constrained predictive polytopic paper. lyapunov inequalities lmis conservativeness lyapunov function. instant lyapunov worst minimized convex approach. instant controller guarantee robustly asymptotically stable. controller meet specifications admissible uncertainties. effectiveness
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10829662
10.1007/s00034-008-9081-4
This paper is concerned with the problem of robust H∞ filtering for uncertain two-dimensional (2-D) systems with intermittent measurements. The parameter uncertainty is assumed to be of polytopic type, and the measurements transmission is assumed to be imperfect, which is modeled by a stochastic variable satisfying the Bernoulli random binary distribution. Our attention is focused on the design of an H∞ filter such that the filtering error system is stochastically stable and preserves a guaranteed H∞ performance. This problem is solved in the parameter-dependent framework, which is much less conservative than the quadratic approach. By introducing some slack matrix variables, the coupling between the positive definite matrices and the system matrices is eliminated, which greatly facilitates the filter design procedure. The corresponding results are established in terms of linear matrix inequalities, which can be easily tested by using standard numerical software. An example is provided to show the effectiveness of the proposed approac
Robust H-infinity filtering for 2-D systems with intermittent measurements
robust h-infinity filtering for 2-d systems with intermittent measurements
concerned robust filtering uncertain intermittent measurements. polytopic imperfect modeled stochastic satisfying bernoulli distribution. focused filter filtering stochastically preserves guaranteed performance. solved conservative quadratic approach. introducing slack definite eliminated greatly facilitates filter procedure. inequalities software. effectiveness approac
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11411793
10.1007/s00034-009-9101-z
A new fully-digital CMOS pulse generator for impulse-radio Ultra-Wide-Band (UWB) systems is presented. First, the shape of the pulse which best fits the FCC regulation in the 3.1-5 GHz sub-band of the entire 3.1-10.6 GHz UWB bandwidth is derived and approximated using rectangular digital pulses. In particular, the number and width of pulses that approximate an ideal template is found through an ad-hoc optimization methodology. Then a fully differential digital CMOS circuit that synthesizes the pulse sequence is conceived and its functionality demonstrated through post-layout simulations. The results show a very good agreement with the FCC requirements and a low power consumptio
A Fully Differential Digital CMOS Pulse UWB Generator
a fully differential digital cmos pulse uwb generator
digital cmos generator impulse ultra presented. fits bandwidth approximated rectangular digital pulses. pulses approximate ideal template methodology. digital cmos circuit synthesizes conceived functionality layout simulations. consumptio
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11080516
10.1007/s00034-010-9205-5
A wide dynamic range and a high sensitivity are often incompatible with each other in analog circuits, such as signal converters or amplifiers. In this paper, we present a method of developing current-to-voltage converters featuring both. It comprises two current-to-voltage conversions. One is to convert the DC component, i.e., the average level of the current input, into a voltage with a nonlinear compression. The other is to apply a ?linear? conversion to the signal component of the input current. This conversion is considered to be ?linear? as the gain is made to be almost constant if the varying signal is rippling at a given current level, and to increase if the level is changed to be lower. Hence, the gain is adaptive to the input current, i.e., getting stronger if the current signal is weaker, and vice versa. This adaptability is implemented by (a) an adaptive bias by means of the voltage converted from the DC component of the input current, and (b) the current-dependent finite drain-source resistances of MOS transistors. A low-pass current filter is used, in the proposed conversion operation, to separate the DC component of the input current from the signal one. We propose, in this paper, a basic structure of the filter and techniques to improve the filtering quality over a wide current range, also an approach to an effective reduction of the effect of the device mismatch as well. A design example of the proposed conversion is presented in this paper. The simulation results have shown its dynamic range of 5-decades and its sensitivity high enough to detect sub-nA current variations
Wide-Dynamic-Range and High-Sensitivity Current-to-Voltage Converters
wide-dynamic-range and high-sensitivity current-to-voltage converters
incompatible analog circuits converters amplifiers. converters featuring both. comprises conversions. convert i.e. compression. conversion current. conversion rippling changed lower. adaptive i.e. getting stronger weaker vice versa. adaptability implemented adaptive converted drain resistances transistors. pass filter conversion one. propose filter filtering mismatch well. conversion paper. decades detect
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52800105
10.1007/s00034-012-9397-y
International audienceAbstract This paper deals with the problem of the Direction Of Arrival (DOA) estimation with nonuniform linear arrays. The proposed method is based on the Expectation Maximization method where ESPRIT is used in the maximization step. The key idea is to iteratively interpolate the data to a virtual uniform linear array in order to apply ESPRIT to estimate the DOA. The iterative approach allows to improve the interpolation using the previously estimated DOA. One of this method novelties lies in its capacity of dealing with any nonuniform array geometry. This technique manifests significant performance and computational advantages over previous algorithms such as Spectral MUSIC, EM-IQML and the method based on manifold separation technique. EM-ESPRIT is shown to be more robust to additive noise. Furthermore, EM-ESPRIT fully exploits the advantages of using a nonuniform array over a uniform array: simulations show that for the same aperture and with less number of sensors, the nonuniform array presents almost identical performance as the equivalent uniform array
Direction of Arrival Estimation using EM-ESPRIT with nonuniform arrays
direction of arrival estimation using em-esprit with nonuniform arrays
audienceabstract deals arrival nonuniform arrays. expectation maximization esprit maximization step. iteratively interpolate virtual array esprit doa. iterative interpolation doa. novelties lies dealing nonuniform array geometry. manifests advantages music iqml manifold technique. esprit robust additive noise. esprit exploits advantages nonuniform array array aperture sensors nonuniform array presents array
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19909231
10.1007/s00034-012-9460-8
This paper describes the distributed information filtering where a set of sensor networks are required to simultaneously estimate input and state of a linear discrete-time system from collaborative manner. Our research purpose is to develop a consensus strategy in which sensor nodes communicate within the network through a sequence of Kalman iterations and data diffusion. A novel recursive information filtering is proposed by integrating input estimation error into measurement data and weighted information matrices. On the fusing process, local system state filtering transmits estimation information using the consensus averaging algorithm, which penalizes the disagreement in a dynamic manner. A simulation example is provided to compare the performance of the distributed information filtering with optimal Gillijins–De Moor’s algorithm
Distributed information consensus filters for simultaneous input and state estimation
distributed information consensus filters for simultaneous input and state estimation
describes filtering sensor simultaneously collaborative manner. consensus sensor communicate kalman iterations diffusion. recursive filtering integrating weighted matrices. fusing filtering transmits consensus averaging penalizes disagreement manner. filtering gillijins–de moor’s
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11081300
10.1007/s00034-012-9479-x
A piecewise nonlinear approach to the nonlinear circuit design has been proposed in this paper. It is to approximate a target nonlinear transfer function by a particular combination of selected nonlinear pieces. The pieces can be produced by one or more analog blocks involving nonlinear devices. This approach can be applied to design nonlinear circuits to implement various current transfer functions. By controlling the operation modes of the transistor pair in a simple current mirror, one can modulate the current transfer function in a radical or fine-tuning manner. It is thus possible for the same current mirror to generate very different nonlinear pieces in different sections of its input range. In order that the control is done automatically by the input current, or in other words, the operation of the transistors is made to be input-current-dependent in a controlled manner, a series structure of two transistors has been proposed to be incorporated in the current mirror. The dependency can be made different by placing the structure in different places of the current mirror and/or by making the two transistors complementary or not, which makes the variations of the nonlinear function. Several current mirrors have been designed. Each of them consists of a very small number of transistors and performs a defined nonlinear current transfer function. The circuits have been simulated with HSPICE to validate the functions. The successful results have been obtained and are presented in the paper
Piecewise Nonlinear Approach to the Implementation of Nonlinear Current Transfer Functions
piecewise nonlinear approach to the implementation of nonlinear current transfer functions
piecewise circuit paper. approximate pieces. pieces analog blocks involving devices. circuits implement functions. controlling transistor mirror modulate radical fine tuning manner. mirror pieces range. automatically transistors manner transistors incorporated mirror. dependency placing places mirror transistors complementary function. mirrors designed. transistors performs function. circuits hspice validate functions. successful
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52058573
10.1007/s00034-013-9610-7
Published version of an article in the journal: Circuits, Systems, and Signal Processing. Also available from the publisher at: http://dx.doi.org/10.1007/s00034-013-9610-7This paper is concerned with the problem of input-output finite-time stability (IO-FTS) for discrete impulsive switched systems with state delays. Sufficient conditions are presented for the existence of IO-FTS for such systems under the cases of certain switching, arbitrary switching, and uncertain switching. All the obtained results are formulated in a set of linear matrix inequalities (LMIs). Two numerical examples are given to illustrate the effectiveness of the proposed results
Input-output finite-time stability of discrete-time impulsive switched linear systems with state delays
input-output finite-time stability of discrete-time impulsive switched linear systems with state delays
circuits processing. publisher concerned impulsive switched delays. switching switching uncertain switching. formulated inequalities lmis illustrate effectiveness
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52113685
10.1007/s00034-013-9737-6
Published version of an article in the journal: Circuits, Systems, and Signal Processing. Also available from the publisher at: http://dx.doi.org/10.1007/s00034-013-9737-6This paper investigates the problem of L1 observer design for positive switched systems. Firstly, a new kind of positive L1 observer is proposed for positive switched linear delay-free systems with observable and unobservable subsystems. Based on the average dwell time approach, a sufficient condition is proposed to ensure the existence of the positive L1 observer. Under the condition obtained, the estimated error converges to zero exponentially, and the L1 -gain from the disturbance input to the estimated error is less than a prescribed level. Then the proposed design result is extended to positive switched systems with mixed time-varying delays, where the mixed time-varying delays are presented in the form of discrete delay and distributed delay. Finally, two numerical examples are given to demonstrate the feasibility of the obtained results
Positive L1 observer design for positive Switched systems
positive l1 observer design for positive switched systems
circuits processing. publisher investigates observer switched systems. firstly kind observer switched delay observable unobservable subsystems. dwell ensure observer. converges exponentially disturbance prescribed level. switched delays delays delay delay. feasibility
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61916201
10.1007/s00034-014-9767-8
“The final publication is available at Springer via http://dx.doi.org/[10.1007/s00034-014-9767-8]”[Abstract] In current digital communication systems, channel information is typically acquired by supervised approaches that use pilot symbols included in the transmit frames. Given that pilot symbols do not convey user data, they penalize throughput spectral efficiency, and transmit energy consumption of the system. Unsupervised channel estimation algorithms could be used to mitigate the aforementioned drawbacks although they present higher computational complexity than that offered by supervised ones. This paper proposes a simple decision method suitable for slowly varying channels to determine whether the channel has suffered a significant variation, which requires to estimate the matrix of the recently changed channel. Otherwise, a previous estimate is used to recover the transmitted symbols. The main advantage of this method is that the decision criterion is only based on information acquired during the time frame synchronization, which is carried out at the receiver. We show that the proposed criterion provides a considerable improvement of computational complexity for both supervised and unsupervised methods, without incurring in a penalization in terms of symbol error ratio. Specifically, we consider systems that make use of the popular Alamouti code. Performance evaluation is accomplished by means of simulated channels as well as making use of indoor wireless channels measured using a testbed
Detection of channel variations to improve channel estimation methods
detection of channel variations to improve channel estimation methods
“the publication springer digital acquired supervised pilot symbols transmit frames. pilot symbols convey penalize throughput transmit system. unsupervised mitigate aforementioned drawbacks offered supervised ones. proposes slowly suffered changed channel. recover transmitted symbols. advantage criterion acquired synchronization receiver. criterion considerable supervised unsupervised incurring penalization symbol ratio. popular alamouti code. accomplished indoor wireless testbed
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76524289
10.1007/s00034-014-9915-1
ParallelLow-DensityParity-Checkandturbocodedecodingconsistsofiter- ative processes that rely on the exchange of messages among multiple processing ele- ments (PEs). They are characterized by complex communication patterns that require area expensive interconnect and memory management. Channel decoders based on Networks-on-Chip (NoCs) have been proposed in the literature, showing unmatched degreesofflexibility,butyieldinghighareaoccupationandpowerconsumption.While general and application-specific power reduction techniques are available to save energy, the gap with respect to dedicated decoders is still large. This paper proposes techniques that reduce and optimize the traffic on the network for NoC-based chan- nel decoders, and can be applied to any NoC architecture. The proposed techniques exploit the probabilistic nature and the processing order of the exchanged messages in the iterative decoding and define novel importance and urgency metrics. Given a target throughput, these techniques allow to consistently reduce and optimize the NoC traffic with minor or no bit error rate (BER) degradation with respect to a decoder with no traffic optimization. An already available NoC-based decoder enhanced with the proposed traffic shaping techniques leads to 13.1 % area overhead and 15.0 % power and energy reduction, while 40.2 % of power is saved on the NoC alon
Reducing the dissipated energy in multi-standard turbo and LDPC decoders
reducing the dissipated energy in multi-standard turbo and ldpc decoders
parallellow densityparity checkandturbocodedecodingconsistsofiter ative rely messages ments expensive interconnect management. decoders chip nocs unmatched degreesofflexibility butyieldinghighareaoccupationandpowerconsumption.while save dedicated decoders large. proposes optimize traffic chan decoders architecture. exploit probabilistic exchanged messages iterative decoding urgency metrics. throughput consistently optimize traffic minor degradation decoder traffic optimization. decoder traffic shaping overhead saved alon
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42411597
10.1007/s00034-015-0206-2
This paper proposes using a previously well-trained deep neural network (DNN) to enhance the i-vector representation used for speaker diarization. In effect, we replace the Gaussian Mixture Model (GMM) typically used to train a Universal Background Model (UBM), with a DNN that has been trained using a different large scale dataset. To train the T-matrix we use a supervised UBM obtained from the DNN using filterbank input features to calculate the posterior information, and then MFCC features to train the UBM instead of a traditional unsupervised UBM derived from single features. Next we jointly use DNN and MFCC features to calculate the zeroth and first order Baum-Welch statistics for training an extractor from which we obtain the i-vector. The system will be shown to achieve a significant improvement on the NIST 2008 speaker recognition evaluation (SRE) telephone data task compared to state-of-the-art approaches
Improved i-vector representation for speaker diarization
improved i-vector representation for speaker diarization
proposes trained enhance speaker diarization. replace mixture train universal trained dataset. train supervised filterbank posterior mfcc train traditional unsupervised features. jointly mfcc zeroth baum welch extractor vector. nist speaker recognition telephone
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42593987
10.1007/s00034-015-0232-0
By extending the least squares-based iterative (LSI) method, this paper presents a decomposition-based LSI (D-LSI) algorithm for identifying linear-in-parameters systems and an interval-varying D-LSI algorithm for handling the identification problems of missing-data systems. The basic idea is to apply the hierarchical identification principle to decompose the original system into two fictitious sub-systems and then to derive new iterative algorithms to estimate the parameters of each sub-system. Compared with the LSI algorithm and the interval-varying LSI algorithm, the decomposition-based iterative algorithms have less computational load. The numerical simulation results demonstrate that the proposed algorithms work quite well
Least squares-based iterative identification methods for linear-in-parameters systems using the decomposition technique
least squares-based iterative identification methods for linear-in-parameters systems using the decomposition technique
extending squares iterative presents decomposition identifying handling missing systems. hierarchical decompose fictitious derive iterative system. decomposition iterative load.
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73440948
10.1007/s00034-015-0233-z
Due to its remarkable energy compaction properties, the discrete cosine transform (DCT) is employed in a multitude of compression standards, such as JPEG and H.265/HEVC. Several low-complexity integer approximations for the DCT have been proposed for both 1-D and 2-D signal analysis. The increasing demand for low-complexity, energy efficient methods require algorithms with even lower computational costs. In this paper, new 8-point DCT approximations with very low arithmetic complexity are presented. The new transforms are proposed based on pruning state-of-the-art DCT approximations. The proposed algorithms were assessed in terms of arithmetic complexity, energy retention capability, and image compression performance. In addition, a metric combining performance and computational complexity measures was proposed. Results showed good performance and extremely low computational complexity. Introduced algorithms were mapped into systolic-array digital architectures and physically realized as digital prototype circuits using FPGA technology and mapped to 45nm CMOS technology. All hardware-related metrics showed low resource consumption of the proposed pruned approximate transforms. The best proposed transform according to the introduced metric presents a reduction in power consumption of 21--25%.Comment: 21 pages, 7 figures, 5 table
Energy-efficient 8-point DCT Approximations: Theory and Hardware Architectures
energy-efficient 8-point dct approximations: theory and hardware architectures
remarkable compaction cosine transform multitude compression standards jpeg hevc. integer approximations analysis. costs. approximations arithmetic presented. transforms pruning approximations. arithmetic retention capability compression performance. combining proposed. extremely complexity. mapped systolic array digital architectures physically realized digital prototype circuits fpga mapped cmos technology. hardware metrics resource pruned approximate transforms. transform presents .comment pages
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76989626
10.1007/s00034-017-0505-x
Blind deconvolution is an ill-posed problem. To solve such a prob- lem, prior information, such as, the sparseness of the source (i.e. input) signal or channel impulse responses, is usually adopted. In speech deconvolution, the source signal is not naturally sparse. However, the direct impulse and early reflections of the impulse responses of an acoustic system can be considered as sparse. In this paper, we exploit the channel sparsity and present an algorithm for speech deconvolution, where the dynamic range of the convolutive speech is also used as the prior information. In this algorithm, the estimation of the impulse response and the source signal is achieved by alternating between two steps, namely, the ℓ1 regularized least squares optimization and a proximal operation. As demonstrated in our experiments, the proposed method pro- vides superior performance for deconvolution of a sparse acoustic system, as compared with two state-of-the-art methods
Sparse Blind Speech Deconvolution with Dynamic Range Regularization and Indicator Function
sparse blind speech deconvolution with dynamic range regularization and indicator function
blind deconvolution posed problem. solve prob sparseness i.e. impulse adopted. speech deconvolution naturally sparse. impulse reflections impulse acoustic sparse. exploit sparsity speech deconvolution convolutive speech information. impulse alternating regularized squares proximal operation. vides superior deconvolution sparse acoustic
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42717796
10.1007/s00034-017-0719-y
The Carson and Fry (1937) introduced the concept of variable frequency as a generalization of the constant frequency. The instantaneous frequency (IF) is the time derivative of the instantaneous phase and it is well-defined only when this derivative is positive. If this derivative is negative, the IF creates problem because it does not provide any physical significance. This study proposes a mathematical solution and eliminate this problem by redefining the IF such that it is valid for all monocomponent and multicomponent signals which can be nonlinear and nonstationary in nature. This is achieved by using the property of the multivalued inverse tangent function. The efforts and understanding of all the methods based on the IF would improve significantly by using this proposed definition of the IF. We also demonstrate that the decomposition of a signal, using zero-phase filtering based on the well established Fourier and filter theory, into a set of desired frequency bands with proposed IF produces accurate time-frequency-energy (TFE) distribution that reveals true nature of signal. Simulation results demonstrate the efficacy of the proposed IF that makes zero-phase filter based decomposition most powerful, for the TFE analysis of a signal, as compared to other existing methods in the literature.Comment: 12 pages, 15 figures. arXiv admin note: text overlap with arXiv:1604.0499
Breaking the Limits -- Redefining the Instantaneous Frequency
breaking the limits -- redefining the instantaneous frequency
carson generalization frequency. instantaneous instantaneous positive. creates significance. proposes mathematical eliminate redefining valid monocomponent multicomponent nonstationary nature. multivalued tangent function. efforts decomposition filtering fourier filter desired produces reveals signal. efficacy filter decomposition powerful pages figures. admin overlap
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11248745
10.1007/s00035-007-0743-9
The abandonment of management in Swiss fen meadows has reduced their plant species diversity and the fitness of some typical fen species. We examined whether the resumption of mowing can reverse these effects, and if so, which mechanisms are responsible for community change; we also tested whether restoration success depends on the duration since abandonment. Experimental mowing was applied to 15 montane fen meadows of NE Switzerland that had been abandoned for 4–35 years. After two years of mowing, plant species richness was 11% higher in mown plots (2 m2) than in fallow plots, approaching levels of neighbouring continuously managed fen meadows. In particular, experimental mowing significantly increased the number of fen indicator species (+15%) as well as herbs and woody species (seedlings and saplings), while grass, sedge and rush species richness was not affected. Mowing had little effect on aboveground biomass, but strongly reduced litter mass (-50%) and canopy height (-20%). Seedling densities of two common species showed opposite responses to mowing: they increased in Carex davalliana and decreased in Succisa pratensis, approaching values of continuously mown fen meadows. Duration since abandonment had no significant effect on any of the variables. Our results demonstrate a rapid recovery of montane fen plant communities irrespective of the duration since abandonment (up to 35 years). We conclude that the restoration of pre-fallow plant community composition is likely to be successful if site conditions (hydrology, nutrient status) remain intact and if common habitat specialists are still present in the vegetation and/or seed bank
Restoration of montane fen meadows by mowing remains possible after 4 - 35 years of abandonment
restoration of montane fen meadows by mowing remains possible after 4 - 35 years of abandonment
abandonment swiss meadows diversity fitness species. resumption mowing reverse restoration success abandonment. mowing montane meadows switzerland abandoned years. mowing richness mown plots fallow plots approaching neighbouring continuously managed meadows. mowing indicator herbs woody seedlings saplings grass sedge rush richness affected. mowing aboveground biomass litter canopy seedling densities opposite mowing carex davalliana succisa pratensis approaching continuously mown meadows. abandonment variables. recovery montane communities irrespective abandonment restoration fallow successful hydrology nutrient intact habitat specialists vegetation seed bank
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77160471
10.1007/s00035-007-0797-8
The ability of plants to disperse seeds may be critical for their survival under the current constraints of landscape fragmentation and climate change. Seed dispersal distance would therefore be an important variable to include in species distribution models. Unfortunately, data on dispersal distances are scarce, and seed dispersion models only exist for some species with particular dispersal modes. To overcome this lack of knowledge, we propose a simple approach to estimate seed dispersal distances for a whole regional flora. We reviewed literature about seed dispersal in temperate regions and compiled data for dispersal distances together with information about the dispersal mode and plant traits. Based on this information, we identified seven "dispersal types" with similar dispersal distances. For each type, upper limits for the distance within which 50% and 99% of a species' seeds will disperse were estimated with the 80th percentile of the available values. These distances varied 5000-fold among the seven dispersal types, but generally less than 50-fold within the types. Thus, our dispersal types represented a large part of the variation in observed dispersal distances. The attribution of a dispersal type to a particular species only requires information that is already available in databases for most Central European species, i.e. dispersal vector (e.g. wind, animals), the precise mode of dispersal (e.g. dyszoochory, epizoochory), and species traits influencing the efficiency of dispersal (e.g. plant height, typical habitats). This typology could be extended to other regions and will make it possible to include seed dispersal in species distribution models
Seed dispersal distances: a typology based on dispersal modes and plant traits
seed dispersal distances: a typology based on dispersal modes and plant traits
disperse seeds landscape fragmentation change. seed dispersal models. unfortunately dispersal distances scarce seed dispersal modes. overcome propose seed dispersal distances flora. reviewed seed dispersal temperate compiled dispersal distances dispersal traits. seven dispersal dispersal distances. seeds disperse percentile values. distances varied seven dispersal types. dispersal dispersal distances. attribution dispersal databases i.e. dispersal e.g. precise dispersal e.g. dyszoochory epizoochory traits influencing dispersal e.g. habitats typology seed dispersal
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77170003
10.1007/s00035-008-0861-z
For conservation management of endangered plants it is important to know which nutrient(s) control growth of the vegetation, because maintenance of low nitrogen (N), phosphorus (P) or potassium (K) availability requires different management measures. The aim of this study was to determine the type of nutrient limitation for the vegetation in the last remaining site with Saxifraga hirculus in Switzerland, using nutrient ratios in the aboveground vegetation as an indicator. We made vegetation relevees, collected biomass of the vascular plants, and took soil samples in three plots at this site. The biomass was very low (152-231 g m-2), and all three plots were clearly N-limited with N:P ratios of 7-8. Soil extractable N concentrations were generally low, and P and K concentrations were moderate to high, which was consistent with the indicated N limitation. Hence conservation management first of all needs to prevent N-enrichment, and needs to avoid increased mineralization rates through drainage, or the accumulation of N in the system from atmospheric deposition. Therefore N output seems required through for instance grazing or mowing. The current grazing management seems to function well, since total aboveground biomass is very low and S. hirculus has a high abundance in this last remnant
Biomass production of the last remaining fen with Saxifraga hirculus in Switzerland is controlled by nitrogen availability
biomass production of the last remaining fen with saxifraga hirculus in switzerland is controlled by nitrogen availability
conservation endangered nutrient vegetation maintenance nitrogen phosphorus potassium availability measures. nutrient limitation vegetation saxifraga hirculus switzerland nutrient aboveground vegetation indicator. vegetation relevees biomass vascular took plots site. biomass plots extractable moderate limitation. conservation prevent enrichment avoid mineralization drainage accumulation deposition. grazing mowing. grazing aboveground biomass hirculus abundance remnant
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18255656
10.1007/s00035-011-0087-3
Subspecies are usually characterized by sets of morphological discontinuities. By means of common garden experiments, we investigated genetic differentiation in morphological and phenological traits in two geographically disjunct subspecies of Campanula thyrsoides L., i.e. subsp. thyrsoides (= C.* thyrsoides) occurring in the European Alps and Jura Mountains, and subsp. carniolica (= C.* carniolica) occurring in the Southeastern Alps and the Dinaric Arc. Nine out of 16 investigated traits were significantly different between C.* thyrsoides and C.* carniolica. For C.* carniolica inflorescence length was 1.4×, and above-ground biomass 2.7× higher, while flower density was significantly lower. Campanula* carniolica also showed delayed flowering and flower development from bottom to top compared to C.* thyrsoides which flowered from top to bottom. The inflorescence growth was indeterminate and flowering took several weeks in C.* carniolica, whereas C.* thyrsoides showed determinate flowering, rapidly opening all flowers within a few days. This differentiation in flowering phenology is likely to be adaptive. The submediterranean climate favours indeterminate flowering in C.* carniolica, allowing ongoing growth of the inflorescence throughout the long summer until environmental conditions worsen, whereas determinate and early flowering in C.* thyrsoides is favourable in the short growing season in the high Alps where seed production must be secured before temperature drops. Glacial survival in refugia with different climates (alpine vs. submediterranean) may have caused this regional differentiation
Differentiation in morphology and flowering phenology between two Campanula thyrsoides L. subspecies
differentiation in morphology and flowering phenology between two campanula thyrsoides l. subspecies
subspecies morphological discontinuities. garden morphological phenological traits geographically disjunct subspecies campanula thyrsoides i.e. subsp. thyrsoides thyrsoides occurring alps jura mountains subsp. carniolica carniolica occurring southeastern alps dinaric arc. nine traits thyrsoides carniolica. carniolica inflorescence biomass flower lower. campanula carniolica delayed flowering flower thyrsoides flowered bottom. inflorescence indeterminate flowering took carniolica thyrsoides determinate flowering rapidly opening flowers days. flowering phenology adaptive. submediterranean favours indeterminate flowering carniolica allowing ongoing inflorescence summer worsen determinate flowering thyrsoides favourable growing season alps seed secured drops. glacial refugia climates alpine submediterranean
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11290695
10.1007/s00035-012-0102-3
It has been predicted that Northern Europe will experience a rise in temperature of 2.3–5.3°C from now until 2100. This increase in temperature may lead to vegetation change along altitudinal gradients. To test this prediction, we recorded plant-species composition in 1995 and 2005/06 in Swiss pre-alpine fen meadows (800–1400 m a.s.l.). Despite no obvious changes in the management of these fens, overall, plant-species richness (cumulative number of plant species at five plots per site) significantly increased over this period. This was mainly due to an increase in the number of thermophilous, rich-soil indicator and shade indicator species which corresponded to increased community productivity and shading within the vegetation layer. In contrast, fen specialists significantly declined in species numbers. The strongest shift in vegetation composition occurred at the lowest sites, which overall had a higher colonization rate by new species than did sites at higher altitudes. Vegetation change along the altitudinal gradient was also affected by different types of land management: early- flowering species and species with low habitat-specificity had high colonization rates in grazed fens, especially at low altitudes
Profiteers of environmental change in the Swiss Alps: increase of thermophilous and generalist plants in wetland ecosystems within the last 10 years
profiteers of environmental change in the swiss alps: increase of thermophilous and generalist plants in wetland ecosystems within the last 10 years
northern europe vegetation altitudinal gradients. swiss alpine meadows a.s.l. obvious fens richness cumulative plots period. thermophilous indicator shade indicator corresponded productivity shading vegetation layer. specialists declined numbers. strongest vegetation occurred colonization altitudes. vegetation altitudinal flowering habitat specificity colonization grazed fens altitudes
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33625618
10.1007/s00035-015-0152-4
The altitudinal gradient involves changes of the partial pressures of atmospheric gases such as CO2. This omnipresent phenomenon likely represents an evolutionary selective agent. We asked whether high altitude plant species had evolved specific response strategies to cope with high altitude pressure conditions. Plants of the high altitude species Arabis alpina and the low altitude species Arabidopsis thaliana were cultivated in growth chambers with high altitude pressure conditions (corresponding to 3000 m a.s.l.) and low altitude conditions (560 m). In both species, high altitude conditions resulted in the narrowing of stomatal aperture as well as a decrease in leaf area and weight. A. alpina produced significantly more stomata under high altitude conditions compared to low altitude conditions, while A. thaliana did not. Under low altitude conditions, however, stomatal density of A. alpina was smaller compared to A. thaliana. The increase in stomatal density of A. alpina was strongly related to the decrease in the partial pressure of CO2 under high altitude conditions. Thus, the adaptation of the high altitude plant A. alpina to high altitude pressure conditions does not consist in a genetically fixed elevated stomatal density but in a different response strategy of stomatal development to environmental factors compared to the lowland plant A. thaliana. A. alpina developed stomata largely uncoupled from other environmental factors than CO2. The increased stomatal density of A. alpina may ensure an optimal CO2 supply during the periods of favourable weather conditions for photosynthesis that are relatively rare and short in the alpine life zone
Arabis alpina and Arabidopsis thaliana have different stomatal development strategies in response to high altitude pressure conditions
arabis alpina and arabidopsis thaliana have different stomatal development strategies in response to high altitude pressure conditions
altitudinal involves pressures gases omnipresent phenomenon evolutionary selective agent. asked altitude evolved cope altitude conditions. altitude arabis alpina altitude arabidopsis thaliana cultivated chambers altitude a.s.l. altitude altitude resulted narrowing stomatal aperture leaf weight. alpina stomata altitude altitude thaliana not. altitude stomatal alpina thaliana. stomatal alpina altitude conditions. adaptation altitude alpina altitude consist genetically elevated stomatal stomatal lowland thaliana. alpina stomata largely uncoupled stomatal alpina ensure supply favourable weather photosynthesis rare alpine
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162652379
10.1007/s00035-018-0203-8
Light environments can influence variation in plant morphology, development and susceptibility to herbivores. Our research interest was to investigate the patterns of herbivore damage and developmental stability in dioecious understory forb Mercurialis perennis in contrasting light habitats, located at 1700 m a.s.l. on Mt. Kopaonik. Male and female plants from two light habitats, open (a sun-exposed field) and shaded (a spruce forest) were examined with respect to: herbivore damage (percentage of leaf area loss), fluctuating asymetry (FA) as a measurement of developmental stability, plant morphological and, specifically, leaf size traits, as well as biochemical traits relating to nutritional quality and defence, taking into account the possible presence of intersexual differences. Our results show that herbivore damage was significantly higher in open habitat, as well as one out of four univariate FA indices and the multivariate index. Morphological and biochemical traits, apart from defensive compounds, had higher values in the shade, pointing to sun-exposed habitat being more stressful for this species. Intersexual differences were observed for foliar damage, defensive compounds (phenolics and tannins), all leaf size traits, total leaf area, and protein content. Contrasting light habitats affected most of the analysed traits. Both foliar damage and FA were higher in a more stressful habitat; within habitats, no positive correlations were found. Herbivore damage was significantly male biased in open habitat. The analysis of intersexual differences in developmental stability measured by leaf asymmetry levels provided no evidence that female plants were more sensitive to environmental stress.This is a post-peer-review, pre-copyedit version of an article published in Alpine Botany. The final authenticated version is available online at: [http://dx.doi.org/10.1007/s00035-018-0203-8
Patterns of herbivore damage, developmental stability, morphological and biochemical traits in female and male Mercurialis perennis in contrasting light habitats
patterns of herbivore damage, developmental stability, morphological and biochemical traits in female and male mercurialis perennis in contrasting light habitats
environments morphology susceptibility herbivores. herbivore developmental dioecious understory forb mercurialis perennis contrasting habitats a.s.l. kopaonik. habitats exposed shaded spruce forest herbivore leaf fluctuating asymetry developmental morphological leaf traits biochemical traits relating nutritional defence intersexual differences. herbivore habitat univariate indices multivariate index. morphological biochemical traits apart defensive shade pointing exposed habitat stressful species. intersexual foliar defensive phenolics tannins leaf traits leaf content. contrasting habitats analysed traits. foliar stressful habitat habitats found. herbivore biased habitat. intersexual developmental leaf asymmetry stress.this peer copyedit alpine botany. authenticated
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28930895
10.1007/s00037-002-0169-0
We continue the investigation of interactive proofs with bounded communication, as initiated by Goldreich & Håstad (1998). Let <i>L</i> be a language that has an interactive proof in which the prover sends few (say <i>b</i>) bits to the verifier. We prove that the complement $\bar L$ has a <i>constant-round</i> interactive proof of complexity that depends only exponentially on <i>b</i>. This provides the first evidence that for <b>NP</b>-complete languages, we cannot expect interactive provers to be much more "laconic" than the standard <b>NP</b> proof. When the proof system is further restricted (e.g., when b = 1, or when we have perfect completeness), we get significantly better upper bounds on the complexity of $\bar L$.Engineering and Applied Science
On Interactive Proofs with a Laconic Prover
on interactive proofs with a laconic prover
continue interactive proofs initiated goldreich håstad interactive prover sends bits verifier. complement round interactive exponentially languages interactive provers laconic proof. restricted e.g. perfect completeness bounds .engineering
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2419583
10.1007/s00037-005-0189-7
Given a quadratic map Q : K^n -> K^k defined over a computable subring D of a real closed field K, and a polynomial p(Y_1,...,Y_k) of degree d, we consider the zero set Z=Z(p(Q(X)),K^n) of the polynomial p(Q(X_1,...,X_n)). We present a procedure that computes, in (dn)^O(k) arithmetic operations in D, a set S of (real univariate representations of) sampling points in K^n that intersects nontrivially each connected component of Z. As soon as k=o(n), this is faster than the standard methods that all have exponential dependence on n in the complexity. In particular, our procedure is polynomial-time for constant k. In contrast, the best previously known procedure (due to A.Barvinok) is only capable of deciding in n^O(k^2) operations the nonemptiness (rather than constructing sampling points) of the set Z in the case of p(Y)=sum_i Y_i^2 and homogeneous Q. A by-product of our procedure is a bound (dn)^O(k) on the number of connected components of Z. The procedure consists of exact symbolic computations in D and outputs vectors of algebraic numbers. It involves extending K by infinitesimals and subsequent limit computation by a novel procedure that utilizes knowledge of an explicit isomorphism between real algebraic sets.Comment: 34 pages, LaTeX (Computational Complexity (cc.cls) class used); updated version, to appear in Comp. Complexit
Polynomial-time computing over quadratic maps I: sampling in real algebraic sets
polynomial-time computing over quadratic maps i: sampling in real algebraic sets
quadratic computable subring computes arithmetic operations univariate representations intersects nontrivially soon faster exponential complexity. a.barvinok capable deciding operations nonemptiness constructing homogeneous symbolic computations outputs algebraic numbers. involves extending infinitesimals utilizes isomorphism algebraic pages latex cc.cls updated comp. complexit
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28930898
10.1007/s00037-007-0233-x
Impagliazzo and Wigderson (36th FOCS, 1998) gave the first construction of pseudorandom generators from a <i>uniform</i> complexity assumption on EXP (namely EXP [not equal to] BPP). Unlike results in the nonuniform setting, their result does not provide a continuous trade-off between worst-case hardness and pseudorandomness, nor does it explicitly establish an average-case hardness result. In this paper: 1. We obtain an optimal worst-case to average-case connection for EXP: if EXP is not a subset of BPTIME(t(n)), EXP has problems that cannot be solved on a fraction 1/2 +1/t'(n) of the inputs by BPTIME(t'(n)) algorithms, for t'=t^{\Omega(1)}. 2. We exhibit a PSPACE-complete self-correctible and downward self-reducible problem. This slightly simplifies and strengthens the proof of Impaglaizzo and Wigderson, which used a a #P-complete problem with these properties. 3. We argue that the results of Impagliazzo and Wigderson, and the ones in this paper, cannot be proved via "black-box" uniform reductions.Engineering and Applied Science
Pseudorandomness and Average-Case Complexity via Uniform Reductions
pseudorandomness and average-case complexity via uniform reductions
impagliazzo wigderson focs gave pseudorandom generators unlike nonuniform trade worst hardness pseudorandomness explicitly establish hardness result. worst connection bptime solved inputs bptime omega exhibit pspace correctible downward reducible problem. simplifies strengthens impaglaizzo wigderson properties. argue impagliazzo wigderson proved reductions.engineering
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48264482
10.1007/s00037-008-0255-z
International audienceDeterministic and probabilistic communication protocols are introduced in which parties can exchange the values of polynomials (rather than bits in the usual setting). It is established a sharp lower bound $2n$ on the communication complexity of recognizing the $2n$-dimensional orthant, on the other hand the probabilistic communication complexity of its recognizing does not exceed 4. A polyhedron and a union of hyperplanes are constructed in $\RR^{2n}$ for which a lower bound $n/2$ on the probabilistic communication complexity of recognizing each is proved. As a consequence this bound holds also for the EMPTINESS and the KNAPSACK problems
Probabilistic communication complexity over the reals
probabilistic communication complexity over the reals
audiencedeterministic probabilistic protocols parties polynomials bits usual sharp recognizing orthant probabilistic recognizing exceed polyhedron union hyperplanes probabilistic recognizing proved. emptiness knapsack
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2119875
10.1007/s00037-010-0286-0
In answer to Ko's question raised in 1983, we show that an initial value problem given by a polynomial-time computable, Lipschitz continuous function can have a polynomial-space complete solution. The key insight is simple: the Lipschitz condition means that the feedback in the differential equation is weak. We define a class of polynomial-space computation tableaux with equally weak feedback, and show that they are still polynomial-space complete. The same technique also settles Ko's two later questions on Volterra integral equations.Comment: 22 pages, 9 figures; preliminary version presented at CCC 200
Lipschitz Continuous Ordinary Differential Equations are Polynomial-Space Complete
lipschitz continuous ordinary differential equations are polynomial-space complete
answer raised computable lipschitz solution. insight lipschitz weak. tableaux equally complete. settles volterra pages preliminary
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2067202
10.1007/s00037-012-0046-4
The Tutte polynomial of a graph G is a two-variable polynomial T(G;x,y) that encodes many interesting properties of the graph. We study the complexity of the following problem, for rationals x and y: given as input a planar graph G, determine T(G;x,y). Vertigan completely mapped the complexity of exactly computing the Tutte polynomial of a planar graph. He showed that the problem can be solved in polynomial time if (x,y) is on the hyperbola H_q given by (x-1)(y-1)=q for q=1 or q=2 or if (x,y) is one of the two special points (x,y)=(-1,-1) or (x,y)=(1,1). Otherwise, the problem is #P-hard. In this paper, we consider the problem of approximating T(G;x,y), in the usual sense of "fully polynomial randomised approximation scheme" or FPRAS. Roughly speaking, an FPRAS is required to produce, in polynomial time and with high probability, an answer that has small relative error. Assuming that NP is different from RP, we show that there is no FPRAS for the Tutte polynomial in a large portion of the (x,y) plane. In particular, there is no FPRAS if x>1, y<-1 or if y>1, x<-1 or if x<0, y<0 and q>5. Also, there is no FPRAS if x<1, y<1 and q=3. For q>5, our result is intriguing because it shows that there is no FPRAS at (x,y)=(1-q/(1+epsilon),-epsilon) for any positive epsilon but it leaves open the limit point epsilon=0, which corresponds to approximately counting q-colourings of a planar graph.Comment: In this revision, significant changes have been made to the structure of the paper to clarify the presentation. Extra detail has been provided at certain points in the proofs, and on at least one occasion the exposition has been made more systematic. Some typos have been corrected. The results are unchanged. 28 pages and 5 figure
Inapproximability of the Tutte polynomial of a planar graph
inapproximability of the tutte polynomial of a planar graph
tutte encodes graph. rationals planar vertigan mapped tutte planar graph. solved hyperbola hard. approximating usual randomised fpras. roughly speaking fpras answer error. fpras tutte portion plane. fpras fpras intriguing fpras epsilon epsilon epsilon leaves epsilon counting colourings planar revision clarify presentation. extra proofs occasion exposition systematic. typos corrected. unchanged. pages
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111365360
10.1007/s00037-012-0049-1
We prove a dichotomy theorem for the rank of propositional contradictions, uniformly generated from first-order sentences, in both the Lovász-Schrijver (LS) and Sherali-Adams (SA) refutation systems. More precisely, we first show that the propositional translations of first-order formulae that are universally false, that is, fail in all finite and infinite models, have LS proofs whose rank is constant, independent of the size of the (finite) universe. In contrast to that, we prove that the propositional formulae that fail in all finite models, but hold in some infinite structure, require proofs whose SA rank grows polynomially with the size of the universe.\ud \ud Until now, this kind of so-called complexity gap theorem has been known for tree-like Resolution and, in somehow restricted forms, for the Resolution and Nullstellensatz systems. As far as we are aware, this is the first time the Sherali-Adams lift-and-project method has been considered as a propositional refutation system (since the conference version of this paper, SA has been considered as a refutation system in several further papers). An interesting feature of the SA system is that it simulates LS, the Lovász-Schrijver refutation system without semi-definite cuts, in a rank-preserving fashion
Rank complexity gap for Lovász-Schrijver and Sherali-Adams proof systems.
rank complexity gap for lovász-schrijver and sherali-adams proof systems.
dichotomy propositional contradictions uniformly sentences lovász schrijver sherali adams refutation systems. precisely propositional translations formulae universally false fail infinite proofs universe. propositional formulae fail hold infinite proofs grows polynomially universe. kind somehow restricted nullstellensatz systems. aware sherali adams lift propositional refutation refutation papers simulates lovász schrijver refutation definite cuts preserving fashion
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51214288
10.1007/s00037-013-0063-y
International audienceWe generalize Kedlaya and Umans' modular composition algorithm to the multivariate case. As a main application, we give fast algorithms for many operations involving triangular sets (over a finite field), such as modular multiplication, inversion, or change of order. For the first time, we are able to exhibit running times for these operations that are almost linear, without any overhead exponential in the number of variables. As a further application, we show that, from the complexity viewpoint, Charlap, Coley, and Robbins' approach to elliptic curve point counting can be competitive with the better known approach due to Elkies
Modular Composition Modulo Triangular Sets and Applications
modular composition modulo triangular sets and applications
audiencewe generalize kedlaya umans modular multivariate case. operations involving triangular modular multiplication inversion order. exhibit running operations overhead exponential variables. viewpoint charlap coley robbins elliptic counting competitive elkies
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2158798
10.1007/s00037-013-0065-9
This paper presents an efficient parallel approximation scheme for a new class of min-max problems. The algorithm is derived from the matrix multiplicative weights update method and can be used to find near-optimal strategies for competitive two-party classical or quantum interactions in which a referee exchanges any number of messages with one party followed by any number of additional messages with the other. It considerably extends the class of interactions which admit parallel solutions, demonstrating for the first time the existence of a parallel algorithm for an interaction in which one party reacts adaptively to the other. As a consequence, we prove that several competing-provers complexity classes collapse to PSPACE such as QRG(2), SQG and two new classes called DIP and DQIP. A special case of our result is a parallel approximation scheme for a specific class of semidefinite programs whose feasible region consists of lists of semidefinite matrices that satisfy a transcript-like consistency condition. Applied to this special case, our algorithm yields a direct polynomial-space simulation of multi-message quantum interactive proofs resulting in a first-principles proof of QIP=PSPACE.Comment: 28 pages. Final version, compiled in letterpaper with reasonable margin
Parallel approximation of min-max problems
parallel approximation of min-max problems
presents problems. multiplicative weights update competitive party referee exchanges messages party messages other. considerably extends admit demonstrating party reacts adaptively other. competing provers collapse pspace dqip. semidefinite programs feasible lists semidefinite satisfy transcript consistency condition. message interactive proofs principles pages. compiled letterpaper reasonable margin
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78071654
10.1007/s00037-014-0084-1
We introduce a notion of the quantum query complexity of a certificate structure. This is a formalization of a well-known observation that many quantum query algorithms only require the knowledge of the position of possible certificates in the input string, not the precise values therein. Next, we derive a dual formulation of the complexity of a non-adaptive learning graph and use it to show that non-adaptive learning graphs are tight for all certificate structures. By this, we mean that there exists a function possessing the certificate structure such that a learning graph gives an optimal quantum query algorithm for it. For a special case of certificate structures generated by certificates of bounded size, we construct a relatively general class of functions having this property. The construction is based on orthogonal arrays and generalizes the quantum query lower bound for the k-sum problem derived recently by Belovs and Špalek (Proceeding of 4th ACM ITCS, 323–328, 2013). Finally, we use these results to show that the learning graph for the triangle problem by Lee et al. (Proceeding of 24th ACM-SIAM SODA, 1486–1502, 2013) is almost optimal in the above settings. This also gives a quantum query lower bound for the triangle sum problem.National Science Foundation (U.S.) (Scott Aaronson’s Alan T. Waterman Award
On the Power of Non-adaptive Learning Graphs
on the power of non-adaptive learning graphs
notion query certificate structure. formalization query certificates precise therein. derive formulation adaptive adaptive tight certificate structures. possessing certificate query certificate certificates property. orthogonal arrays generalizes query belovs špalek proceeding itcs triangle proceeding siam soda settings. query triangle problem.national foundation u.s. scott aaronson’s alan waterman award
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33103594
10.1007/s00037-014-0096-x
In this work, we study rank-one quantum games. In particular, we focus on the study of the computability of the entangled value ω*. We show that the value ω* can be efficiently approximated up to a multiplicative factor of 4. We also study the behavior of ω* under the parallel repetition of rank-one quantum games, showing that it does not verify a perfect parallel repetition theorem. To obtain these results, we first connect rank-one games with the mathematical theory of operator spaces. We also reprove with these new tools essentially known results about the entangled value of rank-one games with one-way communication ω qow . In particular, we show that ω qow can be computed efficiently and it satisfies a perfect parallel repetition theorem
Rank-one quantum games
rank-one quantum games
games. computability entangled efficiently approximated multiplicative repetition games verify perfect repetition theorem. connect games mathematical spaces. reprove essentially entangled games efficiently satisfies perfect repetition
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78071655
10.1007/s00037-015-0099-2
In this paper, we study the following variant of the junta learning problem. We are given oracle access to a Boolean function f on n variables that only depends on k variables, and, when restricted to them, equals some predefined function h. The task is to identify the variables the function depends on.When h is the XOR or the OR function, this gives a restricted variant of the Bernstein–Vazirani or the combinatorial group testing problem, respectively. We analyze the general case using the adversary bound and give an alternative formulation for the quantum query complexity of this problem. We construct optimal quantum query algorithms for the cases when h is the OR function (complexity is Θ(√k) ) or the exact-half function (complexity is O(k[supercript 1/4])). The first algorithm resolves an open problem from Ambainis & Montanaro (Quantum Inf Comput 14(5&6): 439–453, 2014). For the case when h is the majority function, we prove an upper bound of O(k[supercript 1/4]). All these algorithms can be made exact. We obtain a quartic improvement when compared to the randomized complexity (if h is the exact-half or the majority function), and a quadratic one when compared to the non-adaptive quantum complexity (for all functions considered in the paper).National Science Foundation (U.S.) (Scott Aaronson’s Alan T. Waterman Award
Quantum Algorithms for Learning Symmetric Juntas via the Adversary Bound
quantum algorithms for learning symmetric juntas via the adversary bound
variant junta problem. oracle boolean restricted equals predefined on.when restricted variant bernstein–vazirani combinatorial respectively. analyze adversary formulation query problem. query supercript resolves ambainis montanaro comput majority supercript exact. quartic randomized majority quadratic adaptive .national foundation u.s. scott aaronson’s alan waterman award
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78071652
10.1007/s00037-016-0124-0
We consider variants of the minimum circuit size problem MCSP, where the goal is to minimize the size of oracle circuits computing a given function. When the oracle is QBF, the resulting problem MSCP[superscript QBF] is known to be complete for PSPACE under ZPP reductions. We show that it is not complete under logspace reductions, and indeed it is not even hard for TC[superscript 0] under uniform AC[superscript 0] reductions. We obtain a variety of consequences that follow if oracle versions of MCSP are hard for various complexity classes under different types of reductions. We also prove analogous results for the problem of determining the resource-bounded Kolmogorov complexity of strings, for certain types of Kolmogorov complexity measures.National Science Foundation (U.S.) (grants CCF-1064785, CCF-1423544, and CCF-1555409)Natural Sciences and Engineering Research Council of Canada (Discovery Grant
The Minimum Oracle Circuit Size Problem
the minimum oracle circuit size problem
variants circuit mcsp goal minimize oracle circuits function. oracle mscp superscript pspace reductions. logspace reductions superscript superscript reductions. consequences oracle versions mcsp reductions. analogous determining resource kolmogorov strings kolmogorov measures.national foundation u.s. grants council canada discovery
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25047888
10.1007/s00037-016-0135-x
"Help bits" are some limited trusted information about an instance or instances of a computational problem that may reduce the computational complexity of solving that instance or instances. In this paper, we study the value of help bits in the settings of randomized and average-case complexity. Amir, Beigel, and Gasarch (1990) show that for constant $k$, if $k$ instances of a decision problem can be efficiently solved using less than $k$ bits of help, then the problem is in P/poly. We extend this result to the setting of randomized computation: We show that the decision problem is in P/poly if using $\ell$ help bits, $k$ instances of the problem can be efficiently solved with probability greater than $2^{\ell-k}$. The same result holds if using less than $k(1 - h(\alpha))$ help bits (where $h(\cdot)$ is the binary entropy function), we can efficiently solve $(1-\alpha)$ fraction of the instances correctly with non-vanishing probability. We also extend these two results to non-constant but logarithmic $k$. In this case however, instead of showing that the problem is in P/poly we show that it satisfies "$k$-membership comparability," a notion known to be related to solving $k$ instances using less than $k$ bits of help. Next we consider the setting of average-case complexity: Assume that we can solve $k$ instances of a decision problem using some help bits whose entropy is less than $k$ when the $k$ instances are drawn independently from a particular distribution. Then we can efficiently solve an instance drawn from that distribution with probability better than $1/2$. Finally, we show that in the case where $k$ is super-logarithmic, assuming $k$-membership comparability of a decision problem, one cannot prove that the problem is in P/poly by a "black-box proof.
The Value of Help Bits in Randomized and Average-Case Complexity
the value of help bits in randomized and average-case complexity
bits trusted instances solving instances. bits settings randomized complexity. amir beigel gasarch instances efficiently solved bits poly. extend randomized poly bits instances efficiently solved alpha bits cdot efficiently solve alpha instances correctly vanishing probability. extend logarithmic poly satisfies membership comparability notion solving instances bits help. solve instances bits instances drawn independently distribution. efficiently solve drawn super logarithmic membership comparability poly proof.
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29527997
10.1007/s00037-016-0142-y
Schubert polynomials were discovered by A. Lascoux and M. Sch\"utzenberger in the study of cohomology rings of flag manifolds in 1980's. These polynomials generalize Schur polynomials, and form a linear basis of multivariate polynomials. In 2003, Lenart and Sottile introduced skew Schubert polynomials, which generalize skew Schur polynomials, and expand in the Schubert basis with the generalized Littlewood-Richardson coefficients. In this paper we initiate the study of these two families of polynomials from the perspective of computational complexity theory. We first observe that skew Schubert polynomials, and therefore Schubert polynomials, are in $\CountP$ (when evaluating on non-negative integral inputs) and $\VNP$. Our main result is a deterministic algorithm that computes the expansion of a polynomial $f$ of degree $d$ in $\Z[x_1, \dots, x_n]$ in the basis of Schubert polynomials, assuming an oracle computing Schubert polynomials. This algorithm runs in time polynomial in $n$, $d$, and the bit size of the expansion. This generalizes, and derandomizes, the sparse interpolation algorithm of symmetric polynomials in the Schur basis by Barvinok and Fomin (Advances in Applied Mathematics, 18(3):271--285). In fact, our interpolation algorithm is general enough to accommodate any linear basis satisfying certain natural properties. Applications of the above results include a new algorithm that computes the generalized Littlewood-Richardson coefficients.Comment: 20 pages; some typos correcte
Sparse multivariate polynomial interpolation in the basis of Schubert polynomials
sparse multivariate polynomial interpolation in the basis of schubert polynomials
schubert polynomials discovered lascoux utzenberger cohomology rings flag manifolds polynomials generalize schur polynomials multivariate polynomials. lenart sottile skew schubert polynomials generalize skew schur polynomials expand schubert littlewood richardson coefficients. initiate families polynomials perspective theory. skew schubert polynomials schubert polynomials countp evaluating inputs deterministic computes dots schubert polynomials oracle schubert polynomials. runs expansion. generalizes derandomizes sparse interpolation polynomials schur barvinok fomin advances mathematics interpolation accommodate satisfying properties. computes littlewood richardson pages typos correcte
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29552852
10.1007/s00037-017-0158-y
We show that the problem of deciding positivity of Kronecker coefficients is NP-hard. Previously, this problem was conjectured to be in P, just as for the Littlewood-Richardson coefficients. Our result establishes in a formal way that Kronecker coefficients are more difficult than Littlewood-Richardson coefficients, unless P=NP. We also show that there exists a #P-formula for a particular subclass of Kronecker coefficients whose positivity is NP-hard to decide. This is an evidence that, despite the hardness of the positivity problem, there may well exist a positive combinatorial formula for the Kronecker coefficients. Finding such a formula is a major open problem in representation theory and algebraic combinatorics. Finally, we consider the existence of the partition triples $(\lambda, \mu, \pi)$ such that the Kronecker coefficient $k^\lambda_{\mu, \pi} = 0$ but the Kronecker coefficient $k^{l \lambda}_{l \mu, l \pi} > 0$ for some integer $l>1$. Such "holes" are of great interest as they witness the failure of the saturation property for the Kronecker coefficients, which is still poorly understood. Using insight from computational complexity theory, we turn our hardness proof into a positive result: We show that not only do there exist many such triples, but they can also be found efficiently. Specifically, we show that, for any $0<\epsilon\leq1$, there exists $0<a<1$ such that, for all $m$, there exist $\Omega(2^{m^a})$ partition triples $(\lambda,\mu,\mu)$ in the Kronecker cone such that: (a) the Kronecker coefficient $k^\lambda_{\mu,\mu}$ is zero, (b) the height of $\mu$ is $m$, (c) the height of $\lambda$ is $\le m^\epsilon$, and (d) $|\lambda|=|\mu| \le m^3$. The proof of the last result illustrates the effectiveness of the explicit proof strategy of GCT.Comment: 43 pages, 1 figur
On vanishing of Kronecker coefficients
on vanishing of kronecker coefficients
deciding positivity kronecker hard. conjectured littlewood richardson coefficients. establishes formal kronecker littlewood richardson unless subclass kronecker positivity decide. hardness positivity combinatorial kronecker coefficients. algebraic combinatorics. partition triples lambda kronecker lambda kronecker lambda integer holes great witness saturation kronecker poorly understood. insight hardness triples efficiently. epsilon omega partition triples lambda kronecker cone kronecker lambda lambda epsilon lambda illustrates effectiveness pages figur
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42739458
10.1007/s00037-018-0164-8
We introduce a method for transforming low-order tensors into higher-order tensors and apply it to tensors defined by graphs and hypergraphs. The transformation proceeds according to a surgery-like procedure that splits vertices, creates and absorbs virtual edges and inserts new vertices and edges. We show that tensor surgery is capable of preserving the low rank structure of an initial tensor decomposition and thus allows to prove nontrivial upper bounds on tensor rank, border rank and asymptotic rank of the final tensors. We illustrate our method with a number of examples. Tensor surgery on the triangle graph, which corresponds to the matrix multiplication tensor, leads to nontrivial rank upper bounds for all odd cycle graphs, which correspond to the tensors of iterated matrix multiplication. In the asymptotic setting we obtain upper bounds in terms of the matrix multiplication exponent $\omega$ and the rectangular matrix multiplication parameter $\alpha$. These bounds are optimal if $\omega$ equals two. We also give examples that illustrate that tensor surgery on general graphs might involve the absorption of virtual hyperedges and we provide an example of tensor surgery on a hypergraph. Besides its relevance in algebraic complexity theory, our work has applications in quantum information theory and communication complexity.Comment: (accepted for publication in Comm. Complexity
Tensor surgery and tensor rank
tensor surgery and tensor rank
transforming tensors tensors tensors hypergraphs. proceeds splits creates absorbs virtual inserts edges. capable preserving decomposition nontrivial bounds border asymptotic tensors. illustrate examples. triangle multiplication nontrivial bounds tensors iterated multiplication. asymptotic bounds multiplication exponent omega rectangular multiplication alpha bounds omega equals two. illustrate involve virtual hyperedges hypergraph. besides relevance algebraic publication comm.
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73380303
10.1007/s00037-018-0172-8
We present an upper bound on the exponent of the asymptotic behaviour of the tensor rank of a family of tensors defined by the complete graph on $k$ vertices. For $k\geq4$, we show that the exponent per edge is at most 0.77, outperforming the best known upper bound on the exponent per edge for matrix multiplication ($k=3$), which is approximately 0.79. We raise the question whether for some $k$ the exponent per edge can be below $2/3$, i.e. can outperform matrix multiplication even if the matrix multiplication exponent equals 2. In order to obtain our results, we generalise to higher order tensors a result by Strassen on the asymptotic subrank of tight tensors and a result by Coppersmith and Winograd on the asymptotic rank of matrix multiplication. Our results have applications in entanglement theory and communication complexity
Asymptotic tensor rank of graph tensors: beyond matrix multiplication
asymptotic tensor rank of graph tensors: beyond matrix multiplication
exponent asymptotic tensors vertices. exponent outperforming exponent multiplication raise exponent i.e. outperform multiplication multiplication exponent equals generalise tensors strassen asymptotic subrank tight tensors coppersmith winograd asymptotic multiplication. entanglement
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11259528
10.1007/s00038-005-4075-5
OBJECTIVES: The Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) was designed to investigate the health effects from long-term exposure to air pollution. METHODS: The health assessment at recruitment (1991) and at the first reassessment (2001-3) consisted of an interview about respiratory health, occupational and other exposures, spirometry, a methacholine bronchial challenge test, end-expiratory carbon monoxide (CO) measurement and measurement for atopy. A bio bank for DNA and blood markers was established. Heart rate variability was measured using a 24-hour ECG (Holter) in a random sample of participants aged 50 years and older. Concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3) and particulates in ambient air have been monitored in all study areas since 1991. Residential histories collected over the 11 year follow-up period coupled with GIS modelling will provide individual long-term air pollutant exposure estimates. RESULTS: Of 9651 participants examined in 1991, 8715 could be traced for the cohort study and 283 died. Basic information about health status was obtained for 8047 individuals (86% of alive persons), 6 528 individuals (70%) agreed to the health examination and 5 973 subjects (62%) completed the entire protocol. Non-participants in the reassessment were on average younger than participants and more likely to have been smokers and to have reported respiratory symptoms in the first assessment. Average weight had increased by 5.5 kg in 11 years and 28% of smokers in 1991 had quit by the time of the reassessment
Follow-up of the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA 2) 1991-2003: methods and characterization of participants
follow-up of the swiss cohort study on air pollution and lung diseases in adults (sapaldia 2) 1991-2003: methods and characterization of participants
objectives swiss cohort pollution adults sapaldia pollution. recruitment reassessment consisted interview respiratory occupational exposures spirometry methacholine bronchial challenge expiratory monoxide atopy. bank markers established. hour holter aged older. nitrogen dioxide sulphur dioxide ozone particulates ambient monitored residential histories pollutant estimates. traced cohort died. alive persons agreed examination completed protocol. reassessment younger smokers respiratory assessment. smokers quit reassessment
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43316711
10.1007/s00038-006-5063-0
Objectives: To assess whether a community intervention on health related behaviour in deprived neighbourhoods was delivered as planned and the extent of exposure to the intervention programme. Methods: Data were gathered throughout the intervention period using minutes of meetings, registration forms and a postal questionnaire among residents in intervention and comparison neighbourhoods. Results: Overall, the intervention was delivered according to the key principles of a "community approach", although community participation could have been improved. Neighbourhood coalitions organized more than 50 health related activities in the neighbourhoods over a two-year period. Most activities were directed at attracting attention, providing information, and increasing awareness and knowledge, and at changing behaviours. Programme awareness and programme participation were 24% respectively 3% among residents in the intervention neighbourhoods. Conclusions: The process evaluation indicated that it was feasible to implement a community intervention according to the key principles of the "community approach" in deprived neighbourhoods. However, it is unlikely that the total package of intervention activities had enough strength and sufficient exposure to attain community-wide health behaviour change
Process evaluation of a Dutch community intervention to improve health related behaviour in deprived neighbourhoods
process evaluation of a dutch community intervention to improve health related behaviour in deprived neighbourhoods
objectives deprived neighbourhoods delivered planned programme. gathered minutes meetings registration postal questionnaire residents neighbourhoods. delivered principles participation improved. neighbourhood coalitions organized neighbourhoods period. directed attracting awareness changing behaviours. programme awareness programme participation residents neighbourhoods. feasible implement principles deprived neighbourhoods. unlikely package attain
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11254731
10.1007/s00038-008-7077-2
OBJECTIVES: Epidemiological research has confirmed the association between socioeconomic status (SES) and health, but only a few studies considered working conditions in this relationship. This study examined the contribution of physical and psychosocial working conditions in explaining the social gradient in self-rated health. METHODS: A representative sample of 10 101 employees, 5003 women and 5098 men, from the Swiss national health survey 2002 was used. SES was assessed according to the EGP-scheme. Working conditions included exposure to physical disturbances, physical strain, job insecurity, monotonous work and handling simultaneous tasks. For data analysis logistic regression analyses were performed. RESULTS: Data show a social gradient for self-rated health (SRH) as well as for physical and psychosocial working conditions. Logistic regression analysis controlling for age, gender and level of employment showed both physical and psychosocial working conditions to be significant predictors of SRH. Physical and psychosocial working conditions such as physical disturbances from work environment, physical strains in doing the job, monotony at work, job insecurity etc. could explain most of the social gradient of SRH in men and women. CONCLUSION: The study confirmed the relevance of modifiable physical and psychosocial working conditions for reducing social inequality in health. Gender differences need to be considered in epidemiological and intervention studies
Socioeconomic status, working conditions and self-rated health in Switzerland: explaining the gradient in men and women
socioeconomic status, working conditions and self-rated health in switzerland: explaining the gradient in men and women
objectives epidemiological confirmed socioeconomic relationship. psychosocial explaining rated health. employees swiss used. scheme. disturbances insecurity monotonous handling simultaneous tasks. logistic performed. rated psychosocial conditions. logistic controlling gender employment psychosocial predictors srh. psychosocial disturbances monotony insecurity etc. women. confirmed relevance modifiable psychosocial reducing inequality health. gender epidemiological
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186660189
10.1007/s00038-009-0058-2
Objectives To summarize evidence about the costs of limited health literacy (HL) and the cost-effectiveness of interventions to improve limited HL. Methods We performed a systematic review searching electronic databases and additional information resources. We included observational studies and interventional studies with HL-outcomes. We included populations at high risk for low HL and patients with diabetes mellitus or hyperlipidemia. Results We retrieved 2,340 papers and included 10 studies for analysis. The prevalence of limited HL is considerable (range 34–59%). On the health system level, the additional costs of limited HL range from 3 to 5% of the total health care cost per year. On the patient level, the additional expenditures per year per person with limited HL compared to persons with adequate HL range from US $143 to 7,798. Data on the cost-effectiveness of interventions to improve limited HL are scarce. Conclusion The costs of limited HL may be substantial, but few studies were retrieved and the results are heterogeneous
The costs of limited health literacy : a systematic review
the costs of limited health literacy : a systematic review
objectives summarize literacy effectiveness interventions searching databases resources. observational interventional outcomes. mellitus hyperlipidemia. retrieved papers analysis. prevalence considerable year. expenditures person persons adequate effectiveness interventions scarce. substantial retrieved heterogeneous
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11262803
10.1007/s00038-009-0084-0
OBJECTIVES: This study provides information about the prevalence of tobacco prevention (TP) and the stages of change with respect to the introduction of TP among companies in the Canton of Zurich (n = 1,648). It explores the factors that predict restrictiveness of smoking policies, number of individual support measures, interest in services to promote TP, and the relationship between TP and health outcomes. METHODS: Data were gathered by means of a written questionnaire and analysed using ordinal regression models. RESULTS: Whereas many companies maintain smoke-free policies, only few provide cessation-courses. Health and welfare organisations have strictest, and building and hospitality companies have least strict policies. Company size predicts number of individual support measures but not policy restrictiveness. Both measures are predicted by personal concern of the representative. Interest in services is predicted by tobacco-related problems and medium stages of change. Finally, stricter policies are associated with lower proportion of smokers and less tobacco-related problems. CONCLUSIONS: Health professionals should support less advanced companies in their endeavour to implement TP. The findings provide a baseline to evaluate the implementation of the forthcoming smoke-free legislation
Worksite tobacco prevention in the Canton of Zurich: stages of change, predictors, and outcomes
worksite tobacco prevention in the canton of zurich: stages of change, predictors, and outcomes
objectives prevalence tobacco prevention companies canton zurich explores predict restrictiveness smoking policies promote outcomes. gathered questionnaire analysed ordinal models. companies maintain smoke policies cessation courses. welfare organisations strictest hospitality companies strict policies. company predicts restrictiveness. personal concern representative. tobacco change. stricter policies proportion smokers tobacco problems. professionals advanced companies endeavour implement forthcoming smoke legislation
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18154299
10.1007/s00038-009-0097-8
Objective The aim is to analyze and compare individual BMI growth patterns of adults from Switzerland and the U.S. Methods The analyses are based on data from two population representative longitudinal household surveys, one from Switzerland, the other from the U.S. Each data set contains up to four data points for each adult individual. We use multilevel models for growth. Results It can be shown that growth patterns are different in different cohorts in the two countries: there are only small growth differences in the youngest and oldest, but large differences in the middle ages. The individual BMI increase of the middle age Swiss amounts to only half of that in the comparable U.S. individuals. Conclusion Given the much higher BMI level especially in the youngest cohort, this points to severe obesity problems in the U.S. middle aged population in the near future. A positive correlation between individual BMI level and growth may aggravate this fact
Change of individual BMI in Switzerland and the USA: a multilevel model for growth
change of individual bmi in switzerland and the usa: a multilevel model for growth
analyze adults switzerland u.s. longitudinal household surveys switzerland u.s. individual. multilevel growth. cohorts youngest oldest ages. swiss amounts comparable u.s. individuals. youngest cohort obesity u.s. aged future. aggravate
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16161717
10.1007/s00038-009-5411-y
Contains fulltext : 77252.pdf (author's version ) (Open Access)Objective: To examine trends in the prevalence of monthly alcohol use and lifetime drunkenness among 15 year olds in 20 European countries, the Russian Federation, Israel, the United States of America, and Canada. Methods: Alcohol use prevalence and drunkenness were assessed in the Health Behavior in School-aged Children Survey conducted in each country in 1998, 2002, and 2006. Trends were determined using the Cochran-Mantel-Haenszel test for trends. Results: Average monthly alcohol use across all countries declined from 45.3 % to 43.6 % and drunkenness declined from 37.2% to 34.8. There was substantial variability across countries, with decreases in some countries and increases or no change in use or drunkenness in others. The overall decline was greater among boys, from 41.2 % to 36.7 % than among girls, 33.3 % to 31.9 %. In most of the countries where drinking or drunkenness increased, it was due mainly to increases among girls. Conclusions: Trends in alcohol use and drunkenness varied by country. Drinking and drunkenness remained higher among boys than girls, but the gap between boys and girls declined and girls appear to be catching up with boys in some countries
Gender specific trends in alcohol use: cross-cultural comparisons from 1998 to 2006 in 24 countries and regions
gender specific trends in alcohol use: cross-cultural comparisons from 1998 to 2006 in 24 countries and regions
fulltext .pdf examine prevalence monthly alcohol lifetime drunkenness olds russian federation israel america canada. alcohol prevalence drunkenness aged cochran mantel haenszel trends. monthly alcohol declined drunkenness declined substantial drunkenness others. decline boys girls drinking drunkenness girls. alcohol drunkenness varied country. drinking drunkenness remained boys girls boys girls declined girls catching boys
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16161475
10.1007/s00038-009-5416-6
Contains fulltext : 77010.pdf (author's version ) (Open Access)Objective: Because the potential for electronic media communication (EMC) has increased greatly, it is of interest to describe trends in EMC between adolescents and their friends and to investigate whether EMC facilitate or supersede face-to-face contacts among peers. Methods: Answers of 275,571 adolescents concerning contacting friends by means of the phone, text messages, and the internet (i.e. EMC), the number of close friends, and the number of afternoons and evenings per week spent out with friends were analysed by means of chi(2)-tests; and multiple regression. Results: In 2006, between more than one third (11-year olds) and nearly two thirds (15-year olds) communicated electronically with their friends daily or nearly daily. From 2002 to 2006, EMC increased in almost all participating countries. Particularly high increases were found in Eastern Europe. Across countries, the higher the frequency of EMC the higher the number of afternoons and evenings spent with friends. Conclusion: The results are surprisingly consistent across the 31 countries and suggest that EMC among adolescents facilitate rather than supersede face-to-face peer contacts.8 p
Electronic media communication with friends from 2002 to 2006 and links to face-to-face contacts in adolescence: an HBSC study in 31 European and North American countries and regions
electronic media communication with friends from 2002 to 2006 and links to face-to-face contacts in adolescence: an hbsc study in 31 european and north american countries and regions
fulltext .pdf greatly adolescents friends facilitate supersede contacts peers. answers adolescents concerning contacting friends phone messages internet i.e. friends afternoons evenings week spent friends analysed regression. olds nearly thirds olds communicated electronically friends nearly daily. participating countries. eastern europe. afternoons evenings spent friends. surprisingly adolescents facilitate supersede peer contacts.
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11272992
10.1007/s00038-010-0139-2
OBJECTIVES: Family members continue to play a prominent role in decisions to donate organs at the time of death. Prior knowledge of the deceased's intention to donate was identified as an important influential factor in the donation decision-making process. This study examined what factors lead to family communication of a person's wish regarding organ donation. METHODS: A population-based survey was used to identify the prevalence of people who had informed family members of their intention to donate. Associated factors were evaluated using bivariate and multivariate analyses. RESULTS: Multivariate analysis revealed that communication to a family member of the intention to donate organs was more likely if the respondent had a signed donor card (OR = 10.23, CI = 5.25-19.93), had a family discussion on organ donation or transplantation (OR = 7.12, CI = 4.91-10.34), had a partner and knew his or her attitude to organ donation (OR = 5.76, CI = 4.20-7.90), had previously personally had a good look at the issue of organ donation (OR = 2.59, CI = 1.79-3.75), was rather younger (OR = 0.98, CI = 0.97-0.99), was of Swiss nationality (OR = 2.21, CI = 1.25-3.91), felt that he or she was sufficiently informed (OR = 2.10, CI = 1.50-2.94), had the information necessary to come to an appropriate decision on organ donation and-although this relation may be weaker-were (rather) willing to become an organ donor after death (OR = 1.41, CI = 1.01-1.97). CONCLUSIONS: Our findings highlight the need for public education and community campaigns to promote the need to share with others, the intention to donate and to increase people's knowledge on this issue
Predictors of family communication of one's organ donation intention in Switzerland
predictors of family communication of one's organ donation intention in switzerland
objectives continue prominent decisions donate organs death. deceased intention donate influential donation process. person wish organ donation. prevalence informed intention donate. bivariate multivariate analyses. multivariate member intention donate organs respondent signed donor card organ donation transplantation partner knew attitude organ donation personally look organ donation younger swiss nationality felt sufficiently informed come organ donation weaker willing organ donor highlight campaigns promote share intention donate
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2808551
10.1007/s00038-010-0196-6
To determine the prevalence of adolescent smoking in the Russian Federation and examine what factors are associated with it. Data were drawn from Round 13 of the Russia Longitudinal Monitoring Survey (RLMS) carried out in 2004. The sample consists of 815 adolescents (430 boys, 385 girls) aged 14-17 years who answered questions about their health behaviours. Smoking was more prevalent among boys than girls (26.1 vs. 5.7%). Maternal smoking and adolescent alcohol use were associated with smoking among both sexes. The self-assessment of one's socioeconomic position as unfavourable was associated with girls' smoking, while living in a disrupted family, physical inactivity and having a low level of self-esteem were predictive of boys' smoking. The family environment appears to be an important determinant of adolescent smoking in Russia. In particular, boys and girls may be modelling the negative health behaviour lifestyles of their parents, with unhealthy behaviours clustering. Efforts to reduce adolescent smoking in Russia must address the negative effects emanating from the parental home whilst also addressing associated behaviours such as alcohol use
The social determinants of adolescent smoking in Russia in 2004
the social determinants of adolescent smoking in russia in 2004
prevalence adolescent smoking russian federation examine drawn round russia longitudinal rlms adolescents boys girls aged answered behaviours. smoking prevalent boys girls maternal smoking adolescent alcohol smoking sexes. socioeconomic unfavourable girls smoking living disrupted inactivity esteem predictive boys smoking. determinant adolescent smoking russia. boys girls lifestyles parents unhealthy behaviours clustering. efforts adolescent smoking russia emanating parental home whilst addressing behaviours alcohol
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12954371
10.1007/s00038-010-0203-y
OBJECTIVES: The aim of this paper was to explore connection between aspects of self and levels of physical activity among adolescents. METHODS: An international sample of 501 elementary school students (mean age 14.7 +/- 0.9 years, 48.5% males) from the Slovak and Czech Republics completed the Self-competence/Self-liking Scale, the Rosenberg's Self-esteem Scale, the Self-efficacy Scale and a question on their physical activity. Respondents were divided into three groups: (1) no physical activity; (2) infrequent physical activity; (3) everyday physical activity. Data were explored with one-way analysis of variance (ANOVA) separately for each gender. RESULTS: Boys with no physical activity had lower self-liking and social self-efficacy in comparison with boys with everyday physical activity. Girls with no physical activity had lower positive self-esteem, self-liking, self-competence, general and social self-efficacy and higher negative self-esteem in comparison with girls with infrequent and everyday physical activity. CONCLUSION: Regular physical activity is connected with psychological aspects of self among adolescents, especially girls. Incorporating physical activity into the life of youths on a regular basis might lead to the enhancement of their feelings of self-worth and self-efficacy
Aspects of self differ among physically active and inactive youths
aspects of self differ among physically active and inactive youths
objectives explore connection adolescents. elementary males slovak czech republics completed competence liking rosenberg esteem efficacy activity. respondents divided infrequent everyday activity. explored anova separately gender. boys liking efficacy boys everyday activity. girls esteem liking competence efficacy esteem girls infrequent everyday activity. psychological adolescents girls. incorporating youths enhancement feelings worth efficacy
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28939429
10.1007/s00038-011-0266-4
Objectives: The objective of this study was to update an in-depth analysis of the time trend for prostate cancer (PCA) mortality in the population of Tyrol by 5 years, namely to 2008. In Tyrol, prostate-specific antigen (PSA) tests were introduced in 1988/89; more than three-quarters of all men in the age group 45–74 had at least one PSA test in the past decade. Methods: We applied the same model as in a previous publication, i.e., an age-period-cohort model using Poisson regression, to the mortality data covering more than three decades from 1970 to 2008. Results: For Tyrol from 2004 to 2008 in the age group 60+ period terms show a significant reduction in prostate cancer mortality with a risk ratio of 0.70 (95% confidence interval 0.57, 0.87) for Tyrol, and for Austria excluding Tyrol a moderate reduction with a risk ratio of 0.92 (95% confidence interval 0.87, 0.97), each compared to the mortality rate in the period 1989–1993. Conclusions: This update strengthens our previously published results, namely that PSA testing offered to a population at no charge can reduce prostate cancer mortality. The extent of mortality reduction is in line with that reported in the other recent publications. However, our data do not permit us to fully assess the harms associated with PCA screening, and no recommendation for PSA screening can be made without a careful evaluation of overdiagnosis and overtreatment
Prostate-Specific Antigen Testing in Tyrol, Austria: Prostate Cancer Mortality Reduction Was Supported by an Update with Mortality Data up to 2008
prostate-specific antigen testing in tyrol, austria: prostate cancer mortality reduction was supported by an update with mortality data up to 2008
objectives update prostate tyrol tyrol prostate antigen quarters decade. publication i.e. cohort poisson covering decades tyrol prostate confidence tyrol austria excluding tyrol moderate confidence update strengthens offered prostate mortality. publications. permit harms screening recommendation screening careful overdiagnosis overtreatment
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18151785
10.1007/s00038-011-0297-x
OBJECTIVES: To compare the prevalence and management of cardiovascular risk factors (CVRFs) between immigrant groups and Swiss nationals. METHODS: The Swiss Health Surveys (SHS, N = 49,245) and CoLaus study (N = 6,710) were used. Immigrant groups from France, Germany, Italy, Portugal, Spain, former Yugoslavia, other European and other countries were defined. RESULTS: Immigrants from Italy, France, Portugal, Spain and former Yugoslavia presented a higher prevalence of smoking than Swiss nationals. Immigrants reported less hypertension than Swiss nationals, but the differences were reduced when blood pressure measurements were used. The prevalence of dyslipidaemia was similar between immigrants and Swiss nationals in the SHS. When eligibility for statin treatment was assessed, immigrants from Italy were more frequently eligible than Swiss nationals. Immigrants from former Yugoslavia presented a lower prevalence of diabetes in the SHS, but a higher prevalence in the CoLaus study. Most differences between immigrant groups and Swiss nationals disappeared after adjusting for age, leisure-time physical activity, being overweight/obesity and education. CONCLUSIONS: Most CVRFs are unevenly distributed among immigrant groups in Switzerland, but these differences are due to disparities in age, leisure-time physical activity, being overweight/obesity and education
The prevalence and management of cardiovascular risk factors in immigrant groups in Switzerland.
the prevalence and management of cardiovascular risk factors in immigrant groups in switzerland.
objectives prevalence cardiovascular cvrfs immigrant swiss nationals. swiss surveys colaus used. immigrant portugal spain former yugoslavia defined. immigrants portugal spain former yugoslavia prevalence smoking swiss nationals. immigrants hypertension swiss nationals used. prevalence dyslipidaemia immigrants swiss nationals shs. eligibility statin immigrants frequently eligible swiss nationals. immigrants former yugoslavia prevalence prevalence colaus study. immigrant swiss nationals disappeared adjusting leisure overweight obesity education. cvrfs unevenly immigrant switzerland disparities leisure overweight obesity
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12959237
10.1007/s00038-011-0300-6
Social support is assumed to be a protective social determinant of health. The aim of this cross-sectional study was to explore whether social support from the father, mother and friends mediates or moderates the association between socioeconomic position and self-rated health among adolescents. The sample consisted of 1,863 secondary school students from the Kosice region in Slovakia (mean age 16.85; 53.3% females, response rate 98.9%). We assessed the mediation and moderation effects of social support from the mother, father and friends on the relation between socioeconomic position and self-rated health, performing binary logistic regression models. Socioeconomic position was measured by parents' education, the family affluence scale and financial strain. Social support from the father mediated the association between family affluence and self-rated health among both males and females and the association between financial strain and self-rated health among males only. No moderating effect of social support on socioeconomic differences in self-rated health was found. Father involvement seems to have the potential to mediate socioeconomic differences in health during adolescence
Does social support mediate or moderate socioeconomic differences in self-rated health among adolescents?
does social support mediate or moderate socioeconomic differences in self-rated health among adolescents?
protective determinant health. sectional explore father mother friends mediates moderates socioeconomic rated adolescents. consisted kosice slovakia females mediation moderation mother father friends socioeconomic rated performing logistic models. socioeconomic parents affluence strain. father affluence rated males females rated males only. moderating socioeconomic rated found. father involvement mediate socioeconomic adolescence
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16187100
10.1007/s00038-011-0323-z
Contains fulltext : 102650pub.pdf (publisher's version ) (Open Access)Objectives To determine the effect of interviewer BMI on self-reported restrained eating in a face-to-face survey and to examine under- and over-reporting using the face-to face study and a postal follow-up. Methods A sample of 1,212 Dutch adults was assigned to 98 interviewers with different BMI who administered an eating questionnaire. To further evaluate misreporting a mail follow-up was conducted among 504 participants. Data were analyzed using two-level hierarchical models. Results Interviewer BMI had a positive effect on restrained eating. Normal weight and pre-obese interviewers obtained valid responses, underweight interviewers stimulated underreporting whereas obese interviewers triggered overreporting. Conclusion In face-to-face interviews self-reported dietary restraint is distorted by interviewer BMI. This result has implications for public health surveys, the more so given the expanding obesity epidemic.5 p
Interviewer BMI effects on under- and over-reporting of restrained eating: Evidence from a national Dutch face-to-face survey and a postal follow-up
interviewer bmi effects on under- and over-reporting of restrained eating: evidence from a national dutch face-to-face survey and a postal follow-up
fulltext pub.pdf publisher objectives interviewer restrained eating examine reporting postal dutch adults assigned interviewers administered eating questionnaire. misreporting participants. hierarchical models. interviewer restrained eating. obese interviewers valid underweight interviewers stimulated underreporting obese interviewers triggered overreporting. interviews dietary restraint distorted interviewer bmi. surveys expanding obesity epidemic.
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156621386
10.1007/s00038-012-0430-5
Objectives: We compared rates of smoking among those aged 45 years and older in Australia, the United States of America and South Korea, and examined cross-national gender differences in key socioeconomic differentials in smoking. Methods: We conducted weighted analyses on cross-sectional data from nationally representative surveys conducted in 2006. Results: Current smoking was more prevalent for males than females in all countries; the gender difference was largest in Korea. Being unpartnered increased the likelihood of smoking in all countries, while greater wealth reduced it. In Korea these effects interacted with gender; both indicators showed larger differentials among women than men. Lower educational attainment increased the likelihood of smoking for all groups except Korean women, among whom high school educated women were less likely to smoke than the tertiary educated. Conclusions: Our findings support a cultural interpretation of gender differences in smoking: in countries with low gender empowerment, gender differences in smoking are greater. With increasing divorce and female tertiary education rates in nations like Korea, we highlight the need for health promotion messages targeted towards older and more educated women
Cross-national gender differences in the socioeconomic factors associated with smoking in Australia, the United States of America and South Korea
cross-national gender differences in the socioeconomic factors associated with smoking in australia, the united states of america and south korea
objectives smoking aged older australia america korea gender socioeconomic differentials smoking. weighted sectional nationally surveys smoking prevalent males females gender korea. unpartnered likelihood smoking wealth korea interacted gender indicators differentials men. educational attainment likelihood smoking korean educated smoke tertiary educated. cultural gender smoking gender empowerment gender smoking greater. divorce tertiary nations korea highlight promotion messages targeted older educated
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43335287
10.1007/s00038-013-0455-4
There is a clear need for effective prevention and treatment interventions to manage the high prevalence of childhood overweight globally. It is well recognised that changes in the social and economic environment in the last three decades have been a major contributor to altered eating and activity patterns resulting in positive energy balance. The most recent update to the Cochrane review of interventions for preventing obesity in children identified that the majority of childhood obesity prevention intervention evaluations were short-term (12 months or less) and largely focussed on individual behaviour change. Also from this review there is now some early evidence that settings-based obesity prevention interventions are effective at reducing body mass index in the short term. However, given the short-term nature of these interventions, sustainability of this change is unclear, and stronger evidence from larger-scale evaluations is needed about what intervention components are feasible to be embedded into children’s settings and systems (e.g. the school environment) to be able to translate and scale up research findings into effective public health approaches. Until recently, effective obesity prevention interventions have largely drawn upon behaviour change theories, which appear to be unlikely to produce sustainable change in outcomes if they do not consider the broader social and environmental context. Models based on ecological theory show the complex interaction between individuals’ behaviour and their broader environments, that influence eating and activity. A community-based, capacity-building approach aims to promote sustainable skill development and increase the ability of individuals to improve environments that promote health outcomes.This presents a promising approach to obesity prevention, and evidence is needed on processes and outcomes of interventions guided by such theories
Improving weight status in childhood: results from the 'eat well be active' community programs
improving weight status in childhood: results from the 'eat well be active' community programs
prevention interventions manage prevalence childhood overweight globally. recognised decades contributor altered eating balance. update cochrane interventions preventing obesity majority childhood obesity prevention evaluations largely focussed change. settings obesity prevention interventions reducing term. interventions sustainability unclear stronger evaluations feasible embedded children’s settings e.g. translate approaches. obesity prevention interventions largely drawn unlikely sustainable broader context. ecological individuals’ broader environments eating activity. aims promote sustainable skill environments promote outcomes.this presents promising obesity prevention interventions guided
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19884073
10.1007/s00038-013-0487-9
OBJECTIVES: The purpose of the present study was to describe health literacy and its association with substance use among young men. METHODS: The present study was part of the Cohort Study on Substance Use Risk Factors that included 11,930 Swiss males participating in initial screening from August 2010 to July 2011. Self-completed questionnaires covered use of three substances and three components of health literacy. RESULTS: Roughly 22 % reported having searched the Internet for health information and 16 % for information on substances over the past 12 months. At-risk and not at-risk users of alcohol (adjusted odds ratio (AOR) = 2.50 and 1.46), tobacco (AOR = 2.51 and 1.79) and cannabis (AOR = 4.86 and 3.53) searched for information about substances significantly more often via the Internet than abstainers. Furthermore, at-risk users reported better knowledge of risks associated with substance use and a marginally better ability to understand health information than abstainers. CONCLUSIONS: Substance users appear to be more informed and knowledgeable about the risks of substance use than non-users. Consequently, interventions that focus only on information provision may be of limited benefit for preventing substance use
Health literacy and substance use in young Swiss men.
health literacy and substance use in young swiss men.
objectives literacy substance men. cohort substance swiss males participating screening august completed questionnaires covered substances literacy. roughly searched internet substances months. alcohol adjusted odds tobacco cannabis searched substances internet abstainers. risks substance marginally abstainers. substance informed knowledgeable risks substance users. interventions provision benefit preventing substance
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16487959
10.1007/s00038-013-0498-6
OBJECTIVES: Child sexual abuse (CSA) is considered a major risk factor for a variety of health problems both in childhood and in later adult life. While population-based surveys aim to establish the real incidence rates of CSA by interviewing potential (past) victims, agency surveys focus on the rates of CSA reported to the authorities. METHODS: We conducted a nationwide agency survey of CSA in Switzerland. Data were collected from 350 agencies through an anonymous online form during a 6-month period. For data collection, we used a modified version of the case reporting form translated from the American National Incidence Study (NIS-4). RESULTS: About 2.68 cases of CSA per 1,000 children per year are disclosed to agencies (1.11 in males, 4.33 in females). This is roughly twice the average incidence rate reported in methodologically similar studies from Canada, the US, and Australia. CONCLUSIONS: In Switzerland, the majority of disclosed cases of CSA are handled by specialized yet semi-public agencies instead of public child welfare agencies or penal authorities. This fact might explain the higher disclosure rates
The tip of the iceberg. Incidence of disclosed cases of child sexual abuse in Switzerland: results from a nationwide agency survey
the tip of the iceberg. incidence of disclosed cases of child sexual abuse in switzerland: results from a nationwide agency survey
objectives sexual abuse childhood life. surveys establish incidence interviewing victims agency surveys authorities. nationwide agency switzerland. agencies anonymous month period. reporting translated incidence disclosed agencies males females roughly twice incidence methodologically canada australia. switzerland majority disclosed handled specialized agencies welfare agencies penal authorities. disclosure
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33298604
10.1007/s00038-014-0545-y
To investigate the effect of a change in second-hand smoke (SHS) exposure on heart rate variability (HRV) and pulse wave velocity (PWV), this study utilized a quasi-experimental setting when a smoking ban was introduced.; HRV, a quantitative marker of autonomic activity of the nervous system, and PWV, a marker of arterial stiffness, were measured in 55 non-smoking hospitality workers before and 3-12 months after a smoking ban and compared to a control group that did not experience an exposure change. SHS exposure was determined with a nicotine-specific badge and expressed as inhaled cigarette equivalents per day (CE/d).; PWV and HRV parameters significantly changed in a dose-dependent manner in the intervention group as compared to the control group. A one CE/d decrease was associated with a 2.3 % (95 % CI 0.2-4.4; p = 0.031) higher root mean square of successive differences (RMSSD), a 5.7 % (95 % CI 0.9-10.2; p = 0.02) higher high-frequency component and a 0.72 % (95 % CI 0.40-1.05; p > 0.001) lower PWV.; PWV and HRV significantly improved after introducing smoke-free workplaces indicating a decreased cardiovascular risk
The effect of workplace smoking bans on heart rate variability and pulse wave velocity of non-smoking hospitality workers
the effect of workplace smoking bans on heart rate variability and pulse wave velocity of non-smoking hospitality workers
smoke utilized quasi smoking introduced. marker autonomic nervous marker arterial stiffness smoking hospitality workers smoking change. nicotine badge inhaled cigarette equivalents changed manner group. successive rmssd pwv. introducing smoke workplaces cardiovascular
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33300793
10.1007/s00038-015-0660-4
Our aim was to derive a short version of the Mobile Phone Problem Use Scale (MPPUS) using data from 412 adolescents of the Swiss HERMES (Health Effects Related to Mobile phonE use in adolescentS) cohort.; A German version of the original MPPUS consisting of 27 items was shortened by principal component analysis (PCA) using baseline data collected in 2012. For confirmation, the PCA was carried out again with follow-up data 1 year later.; PCA revealed four factors related to symptoms of addiction (Loss of Control, Withdrawal, Negative Life Consequences and Craving) and a fifth factor reflecting the social component of mobile phone use (Peer Dependence). The shortened scale (MPPUS-10) highly reflects the original MPPUS (Kendalls' Tau: 0.80 with 90% concordant pairs). Internal consistency of MPPUS-10 was good with Cronbach's alpha: 0.85. The results were confirmed using the follow-up data.; The MPPUS-10 is a suitable instrument for research in adolescents. It will help to further clarify the definition of problematic mobile phone use in adolescents and explore similarities and differences to other technological addictions
Problematic mobile phone use in adolescents : derivation of a short scale MPPUS-10
problematic mobile phone use in adolescents : derivation of a short scale mppus-10
derive mobile phone mppus adolescents swiss hermes mobile phone adolescents cohort. german mppus consisting items shortened principal confirmation later. addiction withdrawal consequences craving fifth reflecting mobile phone peer shortened mppus reflects mppus kendalls concordant consistency mppus cronbach alpha confirmed data. mppus instrument adolescents. clarify problematic mobile phone adolescents explore similarities technological addictions
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43291060
10.1007/s00038-015-0669-8
Objectives: To evaluate educational inequalities in diabetes mortality in Europe in the 2000s, and to assess whether these inequalities differ between genders.Methods: Data were obtained from mortality registries covering 14 European countries. To determine educational inequalities in diabetes mortality, age-standardised mortality rates, mortality rate ratios, and slope and relative indices of inequality were calculated. To assess whether the association between education and diabetes mortality differs between genders, diabetes mortality was regressed on gender, educational rank and ‘gender × educational rank’.Results: An inverse association between education and diabetes mortality exists in both genders across Europe. Absolute educational inequalities are generally larger among men than women; relative inequalities are generally more pronounced among women, the relative index of inequality being 2.8 (95 % CI 2.0–3.9) in men versus 4.8 (95 % CI 3.2–7.2) in women. Gender inequalities in diabetes mortality are more marked in the highest than the lowest educated.Conclusions: Education and diabetes mortality are inversely related in Europe in the 2000s. This association differs by gender, indicating the need to take the socioeconomic and gender dimension into account when developing public health policies
Educational inequalities in diabetes mortality across Europe in the 2000s: the interaction with gender
educational inequalities in diabetes mortality across europe in the 2000s: the interaction with gender
objectives educational inequalities europe inequalities genders.methods registries covering countries. educational inequalities standardised indices inequality calculated. differs genders regressed gender educational ‘gender educational rank’.results genders europe. educational inequalities inequalities pronounced inequality women. gender inequalities marked educated.conclusions inversely europe differs gender socioeconomic gender policies
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33302272
10.1007/s00038-015-0690-y
Quantitative estimates of air pollution health impacts have become an increasingly critical input to policy decisions. The WHO project "Health risks of air pollution in Europe-HRAPIE" was implemented to provide the evidence-based concentration-response functions for quantifying air pollution health impacts to support the 2013 revision of the air quality policy for the European Union (EU).; A group of experts convened by WHO Regional Office for Europe reviewed the accumulated primary research evidence together with some commissioned reviews and recommended concentration-response functions for air pollutant-health outcome pairs for which there was sufficient evidence for a causal association.; The concentration-response functions link several indicators of mortality and morbidity with short- and long-term exposure to particulate matter, ozone and nitrogen dioxide. The project also provides guidance on the use of these functions and associated baseline health information in the cost-benefit analysis.; The project results provide the scientific basis for formulating policy actions to improve air quality and thereby reduce the burden of disease associated with air pollution in Europe
Quantifying the health impacts of ambient air pollutants : recommendations of a WHO/Europe project
quantifying the health impacts of ambient air pollutants : recommendations of a who/europe project
pollution impacts increasingly decisions. risks pollution europe hrapie implemented quantifying pollution impacts revision union experts convened office europe reviewed accumulated commissioned reviews recommended pollutant causal association. indicators morbidity particulate ozone nitrogen dioxide. guidance benefit analysis. formulating thereby burden pollution europe
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41979706
10.1007/s00038-015-0692-9
This research was funded by NHS Health Scotland.Objectives. Previous research finds adolescents expecting to attend university are more likely to demonstrate health-promoting behaviour than those not expecting university attendance. This suggests public health improvements may be achievable by encouraging adolescents to adopt academic goals. We investigate confounders of this putative relationship, focusing on those identified by evolutionary theory. Methods. Multi-level logistic regression was used to analyse the 2010 Scottish Health Behaviour in School-aged Children survey (n = 1834). Results. Adolescents anticipating university attendance exhibited higher levels of engagement in health-protective behaviours (fruit and vegetable consumption, exercise and tooth brushing) and were more likely to avoid health-damaging behaviours (crisps, soft drink and alcohol consumption, tobacco and cannabis use, fighting and intercourse). These relationships persisted when controlling indicators of life history trajectory (pubertal timing, socioeconomic status and father absence). Pupil level: gender, age, perceived academic achievement and peer/family communication and school level: university expectations, affluence, leavers’ destinations, exam performance and school climate were also adjusted. Conclusions. Encouraging adolescents to consider an academic future may achieve public health benefits, despite social factors that might otherwise precipitate poor health via an accelerated life history trajectory.PostprintPeer reviewe
Educational expectations and adolescent health behaviour : an evolutionary approach
educational expectations and adolescent health behaviour : an evolutionary approach
funded scotland.objectives. finds adolescents expecting attend promoting expecting attendance. improvements achievable encouraging adolescents adopt academic goals. confounders putative focusing evolutionary theory. methods. logistic analyse scottish aged results. adolescents anticipating attendance exhibited engagement protective behaviours fruit vegetable exercise tooth brushing avoid damaging behaviours crisps drink alcohol tobacco cannabis fighting intercourse persisted controlling indicators trajectory pubertal timing socioeconomic father pupil gender perceived academic achievement peer expectations affluence leavers’ destinations exam adjusted. conclusions. encouraging adolescents academic benefits precipitate accelerated trajectory.postprintpeer reviewe
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33303079
10.1007/s00038-015-0715-6
Concerns about vaccination lead to under- and no-vaccination. Our objective is to synthesise and expose evidence on individuals' and communities' concerns about vaccination to influence current debates on strategies to improve vaccination coverage in low- and middle-income countries.; Systematic literature review till February 2014, following standard methods. Published and grey literature that focused on individuals and community concerns on childhood vaccinations were selected.; 44 quantitative, qualitative and mixed-methods studies were included. Main reported concerns referred to perceptions of vaccine harms (e.g. attribution of fatal events). Other concerns included programme distrust (mainly due to rumours and conspiracies) and health system unfriendliness.; Concerns about vaccination are widespread and further worsen the challenges related to programmatic and health system barriers to vaccination. There is a disconnection between qualitative and quantitative research which misses the opportunity to quantify what is reported in the former. Strikingly, there is a wealth of evidence on concerns but much lesser evidence on interventions to address them. We welcome World Health Organization initiative to tackle vaccine hesitancy and call for the synthesis of evidence and production of guidance on strategies to address concerns on vaccination
Exposing concerns about vaccination in low- and middle-income countries : a systematic review
exposing concerns about vaccination in low- and middle-income countries : a systematic review
concerns vaccination vaccination. synthesise expose communities concerns vaccination debates vaccination coverage countries. till february methods. grey focused concerns childhood vaccinations selected. qualitative included. concerns referred perceptions vaccine harms e.g. attribution fatal concerns programme distrust rumours conspiracies unfriendliness. concerns vaccination widespread worsen challenges programmatic barriers vaccination. disconnection qualitative misses opportunity quantify former. strikingly wealth concerns lesser interventions them. welcome initiative tackle vaccine hesitancy call guidance concerns vaccination
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35278676
10.1007/s00038-015-0733-4
Objectives To review existing cardiovascular risk models applicable to South Asian populations. Methods A systematic review of the literature using a combination of search terms for “South Asian”, “cardiovascular”, “risk”/“score” and existing risk models for inclusion. South Asian was defined as those residing or with ancestry belonging to the Indian subcontinent. Results The literature search including MEDLINE and EMBASE identified 7560 papers. After fulltext review, 4 papers met the inclusion criteria. Only 1 reported formal measures of model performance. In that study both a modified Framingham model and QRISK2 showed similar good discrimination with AUROCs of 0.73-0.77 with calibration also reasonable in men (0.71-0.93) but poor in women (0.43-0.52). Conclusion Considering the number of South Asians and prevalence of cardiovascular disease, very few studies have reported performance of risk scores in South Asian populations. Furthermore, it was difficult to make comparisons, as many did not provide measures of discrimination, accuracy and calibration. There is a need for further research to evaluate risk models in South Asians, and ideally derive and validate cardiovascular risk models within South Asian populations.JUS is supported by a National Institute of Health Research (NIHR) Clinical Lectureship.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s00038-015-0733-
Cardiovascular Risk Models for South Asian populations: a systematic review
cardiovascular risk models for south asian populations: a systematic review
objectives cardiovascular applicable asian populations. “south asian” “cardiovascular” “risk” “score” inclusion. asian residing ancestry belonging indian subcontinent. medline embase papers. fulltext papers inclusion criteria. formal performance. framingham qrisk discrimination aurocs calibration reasonable asians prevalence cardiovascular asian populations. comparisons discrimination calibration. asians ideally derive validate cardiovascular asian populations.jus nihr lectureship.this manuscript. springer
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84007648
10.1007/s00038-015-0751-2
To investigate the associations between problematic mobile phone use and mental health and behavioural problems in 412 Swiss adolescents owning a mobile phone while controlling for amount of mobile phone use.; Problematic mobile phone use was determined by the MPPUS-10 (Mobile Phone Problem Use Scale) and related to health and behavioural problems by means of multivariable regression modelling.; MPPUS-10 was 4.7 (95 % CI 1.8, 7.6) units higher in girls than in boys, increased significantly with age and was significantly decreased with increasing educational level of the parents. Furthermore, problematic mobile phone use was associated with impaired psychological well-being, impaired parent and school relationships and more behavioural problems but was not related to peer support and social acceptance.; Our study indicates that problematic mobile phone use is associated with external factors such as worse home and school environment and internal factors such as impaired mental health and behavioural problems of the adolescents and thus problematic mobile phone use should be addressed, in particular when dealing with adolescents showing behavioural or emotional problems
Problematic mobile phone use of Swiss adolescents : is it linked with mental health or behaviour?
problematic mobile phone use of swiss adolescents : is it linked with mental health or behaviour?
associations problematic mobile phone behavioural swiss adolescents owning mobile phone controlling mobile phone use. problematic mobile phone mppus mobile phone behavioural multivariable modelling. mppus girls boys educational parents. problematic mobile phone impaired psychological impaired parent behavioural peer acceptance. problematic mobile phone worse home impaired behavioural adolescents problematic mobile phone addressed dealing adolescents behavioural emotional
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77145858
10.1007/s00038-016-0835-7
This study assessed the impact of education on diet and compliance with the national recommendations. The study included 4338 adult participants of the Colaus study, a cross-sectional, population-based study conducted between 2009 and 2012 in Lausanne (Switzerland). Education was categorized as primary, apprenticeship, secondary, and tertiary. Men with primary vs. tertiary education had a lower intake of monounsaturated fatty acids (29.4 vs. 30.9 g/day), iron (11.4 vs. 11.8 mg/day), vitamin A (758.2 vs. 904.2 retinol equivalents/day), and vitamin D (2.3 vs. 3.0 μg/day). Women with primary vs. tertiary education had a lower intake of monounsaturated fatty acids (25.5 vs. 27.4 g/day), fiber (15.6 vs. 17.2 g/day) and iron (9.8 vs. 10.3 mg/day). Men with primary vs. tertiary education had a better compliance with protein recommendations [odds ratio (95 % CI): 2.31 (1.37; 3.90)], while women with primary vs. tertiary education had a better compliance with vitamin A recommendations [odds ratio 1.74 (1.15; 2.65)]. Overall, our results do not confirm a unidirectional association between education and diet, and question the approach of targeted interventions alone in selected educational groups to prevent chronic diseases
Educational differences in dietary intake and compliance with dietary recommendations in a Swiss adult population.
educational differences in dietary intake and compliance with dietary recommendations in a swiss adult population.
diet compliance recommendations. colaus sectional lausanne switzerland categorized apprenticeship tertiary. tertiary intake monounsaturated fatty iron vitamin retinol equivalents vitamin tertiary intake monounsaturated fatty fiber iron tertiary compliance recommendations odds tertiary compliance vitamin recommendations odds confirm unidirectional diet targeted interventions educational prevent
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96709235
10.1007/s00038-016-0886-9
This study was funded in part by a grant from the Scottish Violence Reduction Unit to Peter D Donnelly (no grant number) and partly by a grant from the Scottish School of Public Health to Fergus G Neville (no grant number).Objectives. To explore the views of Scottish offenders on the impact of alcohol on their experience of offending and their lives in general. Further, to explore their views on the concept of Remote Alcohol Monitoring (RAM) as a way to address alcohol misuse upon liberation from prison. Methods. A convenience sample of 12 serving offenders participated in one of three focus groups.Data were analysed using the principles of thematic analysis. Results. Analysis of the data revealed the significant impact of alcohol on the lives of the participants. Key themes included the amount and frequency of alcohol consumption; the association of alcohol with harm; the association of alcohol with offending; previous attempts to reduce alcohol consumption and possible reasons for failure; and the views of the participants on the utility of RAM in relation to crime prevention. Conclusions. This group of offenders had significant issues with alcohol misuse prior to incarceration that had impacted on their offending and resulted in a variety of health and social harms. Participants were generally positive but pragmatic about RAM, recognising that technology alone may not be enough to change deeply ingrained and addictive behaviours.PostprintPeer reviewe
Preliminary research informing policy on remote alcohol monitoring in criminal justice : the Scottish experience
preliminary research informing policy on remote alcohol monitoring in criminal justice : the scottish experience
funded scottish violence peter donnelly partly scottish fergus neville .objectives. explore views scottish offenders alcohol offending lives general. explore views remote alcohol alcohol misuse liberation prison. methods. convenience serving offenders participated groups.data analysed principles thematic analysis. results. alcohol lives participants. themes alcohol alcohol harm alcohol offending attempts alcohol reasons views utility crime prevention. conclusions. offenders alcohol misuse incarceration impacted offending resulted harms. pragmatic recognising deeply ingrained addictive behaviours.postprintpeer reviewe
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77030673
10.1007/s00038-016-0900-2
?? The Author(s) 2016 This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The final publication is available at Springer via http://dx.doi.org/10.1007/s00038-016-0900-2Objectives and main purpose: The aim of this paper was to examine if the multiple environments of the adolescent including family, peers, school and neighbourhood might function as protective health assets against self-harming behaviour during adolescence. Methods: The present study utilised data collected from 1608 respondents aged 15 years as part of the HBSC England Study. Multilevel modelling was undertaken using the package MLwiN (version 2.33) to investigate the potential domains and dimensions of family life, school culture and environment, and neighbourhood factors that may operate as protective health assets. Results: The results indicated that while peer support did not appear to operate as a protective health asset in the context of self-harm, key dimensions of adolescent/ parent interaction and adolescent experience of the school culture and their neighbourhood were associated with reduced likelihood of self-harming behaviours during adolescence. Conclusions: The Findings highlight the significance of belonging and connectedness as important constituent elements of protective health assets for young people. Interventions that address the multiple environments of the young person, may offer an effective means to reduce the levels of self-harm
Self-harm in Adolescence: Protective Health Assets in the Family, School and Community
self-harm in adolescence: protective health assets in the family, school and community
creative commons attribution permits unrestricted reproduction credit creative commons made. publication springer objectives examine environments adolescent peers neighbourhood protective assets harming adolescence. utilised respondents aged hbsc england study. multilevel undertaken package mlwin neighbourhood operate protective assets. peer operate protective asset harm adolescent parent adolescent neighbourhood likelihood harming behaviours adolescence. highlight belonging connectedness constituent protective assets people. interventions environments person offer harm
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79169288
10.1007/s00038-016-0901-1
Contains fulltext : 166462.pdf (publisher's version ) (Open Access)To include nominal and ordinal variables as predictors in regression models, their categories first have to be transformed into so-called 'dummy variables'. There are many transformations available, and popular is 'dummy coding' in which the estimates represent deviations from a preselected 'reference category'. A way to avoid choosing a reference category is effect coding, where the resulting estimates are deviations from a grand (unweighted) mean. An alternative for effect coding was given by Sweeney and Ulveling in 1972, which provides estimates representing deviations from the sample mean and is especially useful when the data are unbalanced (i.e., categories holding different numbers of observation). Despite its elegancy, this weighted effect coding has been cited only 35 times in the past 40 years, according to Google Scholar citations (more recent references include Hirschberg and Lye 2001 and Gober and Freeman 2005). Furthermore, it did not become a standard option in statistical packages such as SPSS and R. The aim of this paper is to revive weighted effect coding illustrated by recent research on the body mass index (BMI) and to provide easy-to-use syntax for SPSS, R, and Stata on http://www.ru.nl/sociology/mt/wec/downloads. For didactical reasons we apply OLS regression models, but it will be shown that weighted effect coding can be used in any generalized linear model.5 p
When size matters: Advantages of weighted effect coding in observational studies
when size matters: advantages of weighted effect coding in observational studies
fulltext .pdf publisher nominal ordinal predictors categories transformed dummy transformations popular dummy coding deviations preselected avoid choosing coding deviations grand unweighted mean. coding sweeney ulveling representing deviations unbalanced i.e. categories holding elegancy weighted coding cited google scholar citations hirschberg gober freeman option packages spss revive weighted coding illustrated syntax spss stata didactical reasons weighted coding model.
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83621748
10.1007/s00038-016-0902-0
Contains fulltext : 168867.pdf (publisher's version ) (Open Access)Sweeney and Ulveling (1972) introduced weighted effect coding, where the estimates for categories of nominal and ordinal variables are deviations from the arithmetic mean, typically from a sample. This somewhat neglected parameterization is preferred over the well-known effect coding (ANOVA) if the data are unbalanced (i.e., when categories hold different numbers of observations) and was recently revived in this journal (te Grotenhuis et al. 2016). In this paper, we show that weighted effect coding can also be applied to regression models with interaction effects. The weighted effect coded interactions represent the additional effects over and above the main effects obtained from the model without these interactions. This is a useful alternative to effect coding when the data are unbalanced as in most observational data. In this contribution, we describe this novel parameterization and provide syntax, data, and examples in SPSS, R, and Stata on http://www.ru.nl/sociology/mt/wec/downloads. For didactical reasons we apply OLS regression models, but weighted effect coded interactions can be used in any generalized linear model. Throughout this text we use the word 'interaction', while other researchers prefer 'moderation'.5 p
A novel method for modelling interaction between categorical variables
a novel method for modelling interaction between categorical variables
fulltext .pdf publisher sweeney ulveling weighted coding categories nominal ordinal deviations arithmetic sample. somewhat neglected parameterization preferred coding anova unbalanced i.e. categories hold revived grotenhuis weighted coding effects. weighted coded interactions. coding unbalanced observational data. parameterization syntax spss stata didactical reasons weighted coded model. word researchers prefer moderation
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154412287
10.1007/s00038-016-0922-9
Objectives: We aimed to assess whether trends in inequalities in mortality during the period 1970–2010 differed between Finland, Norway, England and Wales, France, Italy (Turin) and Hungary. Methods: Total and cause-specific mortality data by educational level and, if available, occupational class were collected and harmonized. Both relative and absolute measures of inequality in mortality were calculated. Results: In all countries except Hungary, all-cause mortality declined strongly over time in all socioeconomic groups. Relative inequalities in all-cause mortality generally increased, but more so in Hungary and Norway than elsewhere. Absolute inequalities often narrowed, but went up in Hungary and Norway. As a result of these trends, Hungary (where inequalities in mortality where almost absent in the 1970s) and Norway (where inequalities in the 1970s were among the smallest of the six countries in this study) now have larger inequalities in mortality than the other four countries. Conclusions: While some countries have experienced dramatic setbacks, others have made substantial progress in reducing inequalities in mortality
Long-term trends of inequalities in mortality in 6 European countries
long-term trends of inequalities in mortality in 6 european countries
objectives aimed inequalities differed finland norway england wales turin hungary. educational occupational harmonized. inequality calculated. hungary declined socioeconomic groups. inequalities hungary norway elsewhere. inequalities narrowed went hungary norway. hungary inequalities absent norway inequalities smallest inequalities countries. experienced dramatic setbacks substantial progress reducing inequalities
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87201046
10.1007/s00038-016-0938-1
OBJECTIVES:To elucidate the association between passive smoking at home and chronic obstructive pulmonary disease (COPD) mortality via a large-scale nationwide cohort study in Japan.METHODS:Never smokers (n = 34,604) aged 40-79 years at baseline (1988-1990; 4884 men, 29,720 women) were included in the analysis. Passive smoking at home was measured based on self-reported frequency of weekly exposure to passive smoking at home. An inverse probability of treatment-weighted competing risk model was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for COPD mortality.RESULTS:During a median follow-up of 16.4 years, 33 participants (10 men, 23 women) died of COPD. The HR for participants exposed to passive smoking at home ≤4 days per week or those who had almost daily exposure to passive smoking at home had a significantly increased risk of COPD mortality (HR 2.40, 95% CI 1.39-4.15, HR 2.88, 95% CI 1.68-4.93, respectively)
Passive smoking and chronic obstructive pulmonary disease mortality: findings from the Japan collaborative cohort study.
passive smoking and chronic obstructive pulmonary disease mortality: findings from the japan collaborative cohort study.
objectives elucidate passive smoking home obstructive pulmonary copd nationwide cohort japan.methods never smokers aged analysis. passive smoking home weekly passive smoking home. weighted competing hazard confidence copd mortality.results died copd. exposed passive smoking home week passive smoking home copd
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84157479
10.1007/s00038-017-0952-y
The World Health Organization has developed ambient air quality guidelines at levels considered to be safe or of acceptable risk for human health. These guidelines are meant to support governments in defining national standards. It is unclear how they are followed.; We compiled an inventory of ambient air quality standards for 194 countries worldwide for six air pollutants: PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide. We conducted literature and internet searches and asked country representatives about national ambient air quality standards.; We found information on 170 countries including 57 countries that did not set any air quality standards. Levels varied greatly by country and by pollutant. Ambient air quality standards for PM2.5, PM10 and SO2 poorly complied with WHO guideline values. The agreement was higher for CO, SO2 (10-min averaging time) and NO2.; Regulatory differences mirror the differences in air quality and the related burden of disease around the globe. Governments worldwide should adopt science based air quality standards and clean air management plans to continuously improve air quality locally, nationally, and globally
Time to harmonize national ambient air quality standards
time to harmonize national ambient air quality standards
ambient guidelines safe acceptable health. guidelines meant governments defining standards. unclear followed. compiled inventory ambient standards worldwide pollutants ozone nitrogen dioxide sulphur dioxide monoxide. internet searches asked representatives ambient standards. standards. varied greatly pollutant. ambient standards poorly complied guideline values. averaging regulatory mirror burden globe. governments worldwide adopt standards clean plans continuously locally nationally globally
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80685542
10.1007/s00038-017-0965-6
Objectives Bullying victimization among schoolchildren is a major public health concern. This paper aims to analyse the changing associations over two decades between bullying victimization and mental well-being in a representative Scottish schoolchildren sample. Methods Data were collected in six rounds of the cross-sectional Health Behaviour in School-aged Children study in Scotland, with 42,312 adolescents (aged 11, 13 and 15 years). Logistic and linear regression were used to examine changes in the association between bullying victimization and mental well-being. Results The prevalence of bullying victimization rates in Scotland increased between 1994 and 2014 for most age-gender groups, apart from 13-year old boys and 15-year old girls. Over time, female victims reported less confidence and happiness and more psychological complaints than their nonbullied counterparts. This worsening effect over time was not observed in boys. Conclusions Overall, our evidence indicates that the associations between bullying victimization and poor mental well-being strengthened overtime for bullied girls. This finding might partly explain the observed deterioration in mental health indicators among Scottish adolescent girls.Publisher PDFPeer reviewe
Trends in bullying victimization in Scottish adolescents (1994-2014) : changing associations with mental well-being
trends in bullying victimization in scottish adolescents (1994-2014) : changing associations with mental well-being
objectives bullying victimization schoolchildren concern. aims analyse changing associations decades bullying victimization scottish schoolchildren sample. rounds sectional aged scotland adolescents aged logistic examine bullying victimization being. prevalence bullying victimization scotland gender apart boys girls. victims confidence happiness psychological complaints nonbullied counterparts. worsening boys. associations bullying victimization strengthened overtime bullied girls. partly deterioration indicators scottish adolescent girls.publisher pdfpeer reviewe
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96708886
10.1007/s00038-017-0997-y
Objectives: This paper explores trends in Scottish adolescents’ body size perceptions and associated mental well-being outcomes. Methods: Data were collected on Scottish 11, 13 and 15-year olds by the Health Behaviour in School-aged Children study between 1990 and 2014 (n=42,312). Logistic regression was used to examine changes in the prevalence of over- and underweight perceptions. Ordinal and linear regression was used to examine changes in the association between body perception and mental well-being. Results: Little change was observed in over- or under-weight perceptions between 1990 and 2014. However, relative to those perceiving their body as ‘about right’, those perceiving themselves as overweight reported decreasing confidence (all groups), decreasing happiness (11- and 13-year old girls) and increasing psychological symptoms (all girls and 15 year-old boys). Perceived underweight is associated with poor well-being, especially in males, but we present little evidence that this is a recent phenomenon. Conclusions: We present evidence suggesting that the influence of body image on adolescent mental health is increasing over time. This may play a role in the recently observed worsening of mental well-being in Scottish adolescents.Publisher PDFPeer reviewe
Trends in the perceived body size of adolescent males and females in Scotland, 1990–2014 : changing associations with mental well-being
trends in the perceived body size of adolescent males and females in scotland, 1990–2014 : changing associations with mental well-being
objectives explores scottish adolescents’ perceptions outcomes. scottish olds aged logistic examine prevalence underweight perceptions. ordinal examine perception being. perceptions perceiving ‘about right’ perceiving overweight decreasing confidence decreasing happiness girls psychological girls boys perceived underweight males phenomenon. adolescent time. worsening scottish adolescents.publisher pdfpeer reviewe
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161283967
10.1007/s00038-017-1003-4
Objectives: The 22 countries of the East Mediterranean Region (EMR) have large populations of adolescents aged 10–24 years. These adolescents are central to assuring the health, development, and peace of this region. We described their health needs. Methods: Using data from the Global Burden of Disease Study 2015 (GBD 2015), we report the leading causes of mortality and morbidity for adolescents in the EMR from 1990 to 2015. We also report the prevalence of key health risk behaviors and determinants. Results: Communicable diseases and the health consequences of natural disasters reduced substantially between 1990 and 2015. However, these gains have largely been offset by the health impacts of war and the emergence of non-communicable diseases (including mental health disorders), unintentional injury, and self-harm. Tobacco smoking and high body mass were common health risks amongst adolescents. Additionally, many EMR countries had high rates of adolescent pregnancy and unmet need for contraception. Conclusions: Even with the return of peace and security, adolescents will have a persisting poor health profile that will pose a barrier to socioeconomic growth and development of the EMR.Full Tex
Adolescent health in the Eastern Mediterranean Region: findings from the global burden of disease 2015 study
adolescent health in the eastern mediterranean region: findings from the global burden of disease 2015 study
objectives east mediterranean adolescents aged years. adolescents assuring peace region. needs. burden morbidity adolescents prevalence behaviors determinants. communicable consequences disasters substantially gains largely offset impacts emergence communicable disorders unintentional injury harm. tobacco smoking risks amongst adolescents. additionally adolescent pregnancy unmet contraception. return peace security adolescents persisting pose barrier socioeconomic emr.full
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161283836
10.1007/s00038-017-1005-2
Objectives: We used GBD 2015 findings to measure the burden of intentional injuries in the Eastern Mediterranean Region (EMR) between 1990 and 2015. Methods: The Global Burden of Disease (GBD) study defines intentional injuries as a combination of self-harm (including suicide), interpersonal violence, collective violence (war), and legal intervention. We estimated number of deaths, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life years (DALYs) for each type of intentional injuries. Results: In 2015, 28,695 individuals (95% UI: 25,474–37,832) died from self-harm, 35,626 (95% UI: 20,947–41,857) from interpersonal violence, and 143,858 (95% UI: 63,554–223,092) from collective violence and legal interventions. In 2015, collective violence and legal intervention was the fifth-leading cause of DALYs in the EMR and the leading cause in Syria, Yemen, Iraq, Afghanistan, and Libya; they account for 49.7% of total DALYs in Syria. Conclusions: Our findings call for increased efforts to stabilize the region and assist in rebuilding the health systems, as well as increasing transparency and employing preventive strategies to reduce self-harm and interpersonal injuries.Full Tex
Intentional injuries in the Eastern Mediterranean Region, 1990–2015: findings from the Global Burden of Disease 2015 study
intentional injuries in the eastern mediterranean region, 1990–2015: findings from the global burden of disease 2015 study
objectives burden intentional injuries eastern mediterranean burden defines intentional injuries harm suicide interpersonal violence collective violence legal intervention. deaths lost ylls lived disability ylds disability adjusted dalys intentional injuries. died harm interpersonal violence collective violence legal interventions. collective violence legal fifth dalys syria yemen iraq afghanistan libya dalys syria. call efforts stabilize assist rebuilding transparency employing preventive harm interpersonal injuries.full
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154420322
10.1007/s00038-017-1018-x
Objectives: Various studies on the health consequences of socio-economic position address social mobility. They aim to uncover whether health outcomes are affected by: (1) social mobility, besides, (2) social origin, and (3) social destination. Conventional methods do not, however, estimate these three effects separately, which may produce invalid conclusions. We highlight that diagonal reference models (DRMs) overcome this problem, which we illustrate by focusing on overweight/obesity (OWOB). Methods: Using conventional methods (logistic-regression analyses with dummy variables) and DRMs, we examine the effects of intergenerational educational mobility on OWOB (BMI ≥ 25 kg/m2) using survey data representative of the Dutch population aged 18–45 (1569 males, 1771 females). Results: Conventional methods suggest that mobility effects on OWOB are present. Analyses with DRMs, however, indicate that no such effects exist. Conclusions: Conventional analyses of the health consequences of social mobility may produce invalid results. We, therefore, recommend the use of DRMs. DRMs also validly estimate the health consequences of other types of social mobility (e.g. intra- and intergenerational occupational and income mobility) and status inconsistency (e.g. in educational or occupational attainment between partners)
Statistical challenges in modelling the health consequences of social mobility: the need for diagonal reference models
statistical challenges in modelling the health consequences of social mobility: the need for diagonal reference models
objectives consequences socio mobility. uncover mobility besides destination. separately invalid conclusions. highlight diagonal drms overcome illustrate focusing overweight obesity owob logistic dummy drms examine intergenerational educational mobility owob dutch aged males females mobility owob present. drms exist. consequences mobility invalid results. recommend drms. drms validly consequences mobility e.g. intra intergenerational occupational mobility inconsistency e.g. educational occupational attainment partners
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