bluuebunny/crossref_metadata_2025 huggingface dataset:
Global weak solutions for coupled transport processes in concrete walls at high temperatures
Authors: Beneš M. , Štefan R.
Published: June 2013

We consider an initial‐boundary value problem for a fully nonlinear coupled parabolic system with nonlinear boundary conditions modeling hygro‐thermal behavior of concrete at high temperatures. We prove a global existence of a weak solution to this system on any physically relevant time interval. The main result is proved by an approximation procedure. This consists in proving the existence of solutions to mollified problems using the Leray‐Schauder theorem, for which a priori estimates are obtained. The limit then provides a weak solution for the original problem. A practical example illustrates a performance of the model for a problem of a concrete segment exposed to transient heating according to three different fire scenarios. Here, the focus is on the short‐term pore pressure build up, which can lead to explosive spalling of concrete and catastrophic failures of concrete structures.
Higher order accurate discontinuous and continuous p‐Galerkin methods for linear elastodynamics
Authors: Gleim T. , Kuhl D.
Published: June 2013

The present paper is concerned with the numerical integration of linear structural dynamics by means of different higher order accurate Galerkin time integration schemes. Firstly the single field discontinuous and continuous p‐Galerkin schemes are developed in a generalized fashion using arbitrary polynomial degrees. In a further step the two field discontinuous and continuous p‐Galerkin schemes are derived. In both algorithmic classes continuous Galerkin schemes are obtained by the strong enforcement of the continuity condition as special case of the discontinuous Galerkin schemes. The related time integration schemes are conditioned in an algorithmic set‐up in such a manner that the implementation is similar to the classical Newmark scheme and its α derivates. Selected benchmark examples demonstrate the excellent dissipation and dispersion behavior and the robustness of the present Galerkin integration schemes. Furthermore, an error analysis, based on the analytical solution and the real local time integration error, verifies the order of accuracy of Galerkin time integration schemes controlled by the chosen polynomial degree. In particular the order of accuracy for each class of Galerkin integration schemes is specified. The comparison of the numerical effort for the classical Newmark scheme and the family of Galerkin schemes indicates advantages for Galerkin schemes: For a prescribed error level higher order Galerkin schemes are more effective than the Newmark scheme.
Infiltration processes in cohesionless soils
Authors: Schaufler A. , Becker C. , Steeb H.
Published: June 2013

In this paper, a thermodynamically consistent four‐phase continuum model in the framework of the mixture theory is presented describing infiltration processes of suspensions in cohesionless granular material. The paper focuses on the distinct form of the constitutive relation for the volume production term of the fluidized particles and its consequences on the infiltration process. To this end a constitutive equation describing infiltration phenomena is proposed which includes only one material parameter. Therefore we study numerically a boundary value problem, which is characterized by a homogeneous field of the hydraulic gradient in the reference configuration at the time t0 = 0. Infiltration is affecting the distribution of the hydraulic properties and illustrates the consequences of the proposed constitutive equation for specific parameter choices. Furthermore it is shown how the material parameter can be estimated without explicit numerical calculations.
On the instability of equilibrium position of a mechanical system with singular constraints
Authors: Čović V. , Mitrović Z. , Rusov S. , Obradović A.
Published: June 2013

The Lyapunov first method generalized to the case of nonlinear differential equations is applied to the study of the instability of the equilibrium position of a mechanical system, whose motion is constrained by singular nonholonomic constraints. Starting from the results of S. D. Furta (On the instability of equilibrium position of constrained mechanical systems) three theorems on the instability are formulated. The first theorem considers the case of nonholonomic constraints that do not satisfy the condition of weak nonholonomity. The other two theorems are related to the case of weakly nonholonomic systems. In each of the formulated theorems it is shown that the minimum form of Maclaurin series for the potential energy has not a local minimum. Thus, a contribution has been made to the inversion of Lagrange's theorem.
Difficulties arising from different definitions of tortuosity for wave propagation in saturated poroelastic media models
Authors: Cowin S.C. , Cardoso L.
Published: June 2013

The multiple definitions of permeability and tortuosity employed by investigators modifying the basic equations of dynamic poroelasticity pose a problem as some resulting analyses produce results conflicting with those of other investigators. When the same words are used to describe different definitions of different concepts, the problem is compounded. These problems were highlighted in recent applications of acceleration wave analyses of dynamic poroelasticity. Wilmanski [40] and Coussy [14] applied acceleration wave analysis to their own systems of dynamic poroelastic equations and found contradictory results. In one case the wave speed depends upon tortuosity and in the other case a dependence upon permeability (and tortuosity) was not allowed. This means that acceleration waves in the Wilmanski [40] analysis cannot exhibit dispersion at lower frequencies. Harmonic wave analyses applied to the same systems of dynamic poroelastic equations predict a dependence of wave speed upon permeability. The acceleration wave analysis of a system of dynamic poroelastic equations is dependent upon the definitions of tortuosity used by the investigators. Wilmanski [40] and Coussy [14] each used their own definition of tortuosity.
On the temporal behaviour in the bending theory of porous thermoelastic plates
Authors: Ghiba I.D.
Published: June 2013

In this paper we consider the bending theory of Mindlin type thermoelastic plates with voids. We study the temporal behaviour of the solution of the boundary‐initial value problem of this theory. Assuming that the internal energy density is positive definite, relations describing the asymptotic behaviour of the Cesáro means of various parts of total energy are established. An extension of the results to a large class of thermoelastic materials with voids is given.
Yielding of two‐layer curved bars under pure bending
Authors: Arslan E. , Sülü İY.
Published: June 2013

Yielding of a curved bar consisting of two layers subject to pure bending is investigated. It is assumed that both layers of the bar are in a state of plane stress and Tresca's yield criterion is used to detect onset of plasticization. Analytical expressions are obtained for the bending moments corresponding to the elastic limit leading to plastic flow. The results show that, depending on material properties and dimensions of the layers, different cases for plastic deformation may occur. Yielding may emerge at the inner or outer surface of the bar or at the interface between two layers. Furthermore, a critical case in which yielding commences at the outer and interface surfaces simultaneously was observed. Numerical results for real engineering materials are presented in graphical form.
Dynamic response of a cracked magnetoelectroelastic layer sandwiched between two elastic layers
Authors: Hu Keqiang , Chen Z.
Published: June 2013

The dynamic response of a cracked magnetoelectroelastic layer sandwiched between dissimilar elastic layers under anti‐plane shear and in‐plane electric and magnetic impacts is investigated by the integral transform method. Fourier transforms and Laplace transforms are applied to reduce the mixed boundary value problem of the impermeable crack to simultaneous dual integral equations, which are then expressed in terms of simultaneous Fredholm integral equations of the second kind. The stress field, electric field and magnetic field near the crack tip are obtained asymptotically, and the corresponding field intensity factors are further determined. Numerical results show that the stress intensity factors are influenced by the material properties, the electric and magnetic loadings, and the geometry. The crack initiation can be enhanced or retarded depending on the electric and magnetic loading, and the crack may propagate along its original crack line when the criterion of maximum hoop stress is applied.
Index reduction for operator differential‐algebraic equations in elastodynamics
Authors: Altmann R.
Published: June 2013

In space semi‐discretized equations of elastodynamics with weakly enforced Dirichlet boundary conditions lead to differential algebraic equations (DAE) of index 3. We rewrite the continuous model as operator DAE and present an index reduction technique on operator level. This means that a semi‐discretization leads directly to an index‐1 system. We present existence results for the operator DAE with nonlinear damping term and show that the reformulated operator DAE is equivalent to the original equations of elastodynamics. Furthermore, we show that index reduction and semi‐discretization in space commute if the discretization schemes are chosen in an appropriate way.
Microstructure and effective behavior of materials
Authors: Dolzmann G.
Published: June 2013

Tailor‐made materials often take advantage of surprising material behavior which is related to special effects and structures on small length scales. In order to achieve the design goals, a precise understanding of the underlying mechanisms in a mathematical model is indispensable. This contribution presents modern methods in the calculus of variations which are available for the analysis and numerical simulation of systems with multiple scales and illustrates their use in two characteristic model examples.
Dynamic contact problem for a von Kármán–Donnell shell
Authors: Bock I. , Jarušek J.
Published: June 2013

The existence of solutions is proved for the unilateral dynamic contact of a von Kármán‐Donnell shell with a rigid obstacle. Both purely elastic material and a material with a singular memory are treated.
A perturbative model for predicting the high‐Reynolds‐number behaviour of the streamwise travelling waves technique in turbulent drag reduction
Authors: Belan M. , Quadrio M.
Published: June 2013

The background of this work is the problem of reducing the aerodynamic turbulent friction drag, which is an important source of energy waste in innumerable technological fields (transportation being probably the most important). We develop a theoretical framework aimed at predicting the behaviour of existing drag reduction techniques when used at the large values of the Reynolds numbers Re which are typical of applications. We focus on one recently proposed and very promising technique, which consists in creating at the wall streamwise‐travelling waves of spanwise velocity (M. Quadrio, P. Ricco, and C. Viotti, J. Fluid Mech. 627, 161–178, 2009). A perturbation analysis of the Navier‐Stokes equations that govern the fluid motion is carried out, for the simplest wall‐bounded flow geometry, i.e. the plane channel flow. The streamwise base flow is perturbed by the spanwise time‐varying base flow induced by the travelling waves. An asymptotic expansion is then carried out with respect to the velocity amplitude of the travelling wave. The analysis, although based on several assumptions, leads to predictions of drag reduction that agree well with the measurements available in literature and mostly computed through Direct Numerical Simulations (DNS) of the full Navier–Stokes equations. New DNS data are produced on purpose in this work to validate our method further. The method is then applied to predict the drag‐reducing performance of the streamwise‐travelling waves at increasing Re, where comparison data are not available. The current belief, based on a Re‐range of about one decade only above the transitional value, that drag reduction obtained at low Re is deemed to decrease as Re is increased is fully confirmed by our results. From a quantitative standpoint, however, our outlook based on several decades of increase in Re is much less pessimistic than other existing estimates, and motivates further, more accurate studies on the present subject.
Classical plate buckling theory as the small‐thickness limit of three‐dimensional incremental elasticity
Authors: Steigmann D.J. , Ogden R.W.
Published: June 2013

Classical plate buckling theory is obtained systematically as the small‐thickness limit of the three‐dimensional linear theory of incremental elasticity with null incremental data. Various a priori assumptions associated with classical treatments of plate buckling, including the Kirchhoff–Love hypothesis, are here derived rather than imposed, and the conditions under which they emerge are stated precisely.
Drug release from collagen matrices including an evolving microstructure
Authors: Ray N. , van Noorden T. , Radu F.A. , Friess W. , Knabner P.
Published: June 2013

Biodegradable collagen matrices have become a promising alternative to traditional drug delivery systems. The relevant mechanisms in controlled drug release are the diffusion of water into the collagen matrix, the swelling of the matrix coming along with drug release, and enzymatic degradation of the matrix with additional simultaneous drug release. These phenomena have been extensively studied in the past experimentally, via numerical simulations as well as analytically. However, a rigorous derivation of the macroscopic model description, which includes the evolving microstructure due to the degradation process, is still lacking. Since matrix degradation leads to the release of physically entrapped active agent, a good understanding of these phenomena is very important. We present such a derivation using formal twoscale asymptotic expansion in a level set framework and complete our results with numerical simulations in comparison with experimental data.
Optimization of concrete shells using genetic algorithms
Authors: Bertagnoli G. , Giordano L. , Mancini S.
Published: June 2013

In structural design, structures are often modeled using the finite elements method (FEM). One of the most common element type is the shell, which is used to model surfaces in a three dimensional space as far as the surface thickness is smaller than the other two dimensions. Many decisions must be taken during the design process, and many physical and loading constraints must be satisfied. Designers are generally interested in providing a solution that respects all the problem constraints, without trying to further improve it. In fact optimization is not trivial, even if it could yield a huge benefit both from the economic and the construction point of view. Additionally, saving materials is one of the fundamental criteria for the sustainable approach to the design. In this paper, we address the Skew Reinforcement Design in Reinforced Concrete Two Dimensional Elements (SRD2D). It consists of determining the minimum reinforcement required to respect all the constraints given by the geometric properties and the internal actions working on it. As this problem is strongly nonlinear and non‐convex it cannot be easily solved using exact methods, while heuristics and meta‐heuristics are suitable to this purpose. We propose a Genetic Algorithm (GA) and an enhanced version of it, a memetic algorithm, in which we apply an intensification heuristic to the solution obtained by the GA, where each variable is separately optimized by applying a first improvement based on local search strategy. We report computational results showing both the effectiveness of the proposed method, and the benefit of combining GAs with intensification methods.
Approximating the vanishing capillarity limit of two‐phase flow in multi‐dimensional heterogeneous porous medium
Authors: Andreianov B. , Brenner K. , Cancès C.
Published: June 2013

Neglecting capillary pressure effects in two‐phase flow models for porous media may lead to non‐physical solutions: indeed, the physical solution is obtained as limit of the parabolic model with small but non‐zero capillarity. In this paper, we propose several numerical strategies designed specifically for approximating physically relevant solutions of the hyperbolic model with neglected capillarity, in the multi‐dimensional case. It has been shown in [Andreianov & Cancès, Comput. Geosci., DOI: 10.1007/s10596‐012‐9329‐8, 2013] that in the case of the one‐dimensional Buckley‐Leverett equation with distinct capillary pressure properties of adjacent rocks, the interface may impose an upper bound on the transmitted flux. This transmission condition may reflect the oil trapping phenomenon. We recall the theoretical results for the one‐dimensional case which are used to motivate the construction of multi‐dimensional finite volume schemes. We describe and discuss a coupled scheme resulting as the limit of the scheme constructed in [Brenner & Cancès & Hilhorst, HAL preprint no.00675681, 2012] and two IMplicit Pressure – Explicit Saturation (IMPES) schemes with different level of coupling. We finally provide numerical evidences of the good behavior of the fully decoupled version of the IMPES scheme.
Liquefaction phenomena in fluid‐saturated soil based on the Theory of Porous Media and the framework of elasto‐plasticity
Authors: Ehlers W. , Schenke M. , Markert B.
Published: June 2013

Liquefaction phenomena are encountered in many engineering applications, especially, in geomechanics and earthquake engineering. Drawing our attention to fluid‐saturated granular materials with heterogeneous microstructures, the modelling is carried out within a continuum‐mechanical framework by exploiting the macroscopic Theory of Porous Media (TPM) together with thermodynamically consistent constitutive equations. In this regard, the solid skeleton of the water‐saturated soil is described as an elasto‐plastic material with isotropic hardening and a stress‐dependent failure surface. The underlying equations are discretised and implemented into the coupled porous‐media finite‐element solver PANDAS and linked to the commercial finite‐element package Abaqus via a general interface. This coupling allows the definition of complex intial‐boundary‐value problems through Abaqus, thereby using the sophisticated material models of PANDAS. To reveal the capabilities of this approach, two types of simulations have been carried out. At first, in order to get a detailed understanding of the porous‐media soil model under transient loading conditions, a cyclic torsion benchmark is computed. In a second step, specific liquefaction phenomena are addressed, where the underlying initial‐boundary‐value problems are inspired by practically relevant scenarios.
A new direct time integration method for the equations of motion in structural dynamics
Authors: Katsikadelis J.T.
Published: June 2013

A direct time integration method is presented for the solution of the equations of motion describing the dynamic response of structural linear and nonlinear multi‐degree‐of‐freedom systems. It applies also to large systems of second order differential equations with fully populated, non symmetric coefficient matrices as well as to equations with variable coefficients. The proposed method is based on the concept of the analog equation, which converts the coupled N equations into a set of single term uncoupled second order ordinary quasi‐static differential equations under appropriate fictitious loads, unknown in the first instance. The fictitious loads are established from the integral representation of the solution of the substitute single term equations. The method is simple to implement. It is self starting, unconditionally stable and accurate and conserves energy. It performs well when large deformations and long time durations are considered and it can be used as a practical method for integration of the equations of motion in cases where widely used time integration procedures, e.g. Newmark's, become unstable. Several examples are presented, which demonstrate the efficiency of the method. The method can be straightforward extended to evolution equations of order higher than two.
Accounting for differential swelling in the multi‐physics modelling of the diffusive behaviour of polymers
Authors: Sar B.E. , Fréour S. , Davies P. , Jacquemin F.
Published: June 2013

The purpose of this paper is to take into account the derivative by moisture content of polymer volume in order to establish a diffusion law within the so‐called “thermodynamical approach” for a polymer material which experiences a hygro‐mechanical load. In this study, the specific case corresponding to the existence of unsymmetrical hygroscopic boundary conditions was investigated.
Stability of the rotating compressed nano‐rod
Authors: Atanackovic T.M. , Zorica D.
Published: June 2013

We study stability of a rotating compressed nano‐rod clamped at one and free at the other end. By using the Euler method of adjacent equilibrium configuration, we determine critical values for angular speed and compressive force. Post‐critical shape of the rod is obtained by solving the non‐linear system of equilibrium equations for several values of parameters.
Asymptotic decomposition in the problem of joined elastic beams
Authors: Kolpakov A.G. , Andrianov I.V.
Published: June 2013

The analysis of problem of joined elastic beams is presented in comparison with the engineering and asymptotic approaches. Our analysis is based on three‐dimensional elasticity theory model and recently developed method of local perturbation (Gaudiello and Kolpakov, 2011), which seems to be an effective tool for analysis of fields in the vicinity of joint. We demonstrate that the method of local perturbation developed in (Gaudiello and Kolpakov, 2011) for scalar Laplace equation can be modified for vectorial elasticity theory problem. We demonstrate that the elasticity theory problem in joined domains of small diameter can be decomposed into one‐dimensional problem describing global deformation of a system of joined beams and three‐dimensional problems describing local deformation of singular joints in uniform fields. The first problem is the classical one, which ignores individual properties of joint absolutely. The second problem initiates reminiscence about the cellular problem of the homogenization theory for periodic structure. In spite of some similarities, the mentioned problems differ significantly. In particular, the joint of normal type (the joint similar in dimensions and material characteristics to the joined beams) does not manifest itself on global level. Due to the strong localization of perturbation of solution, computation of local strains and stresses in the vicinity of joint can be realized with standard FEM software.
Chiral description of massive gravity
Authors: Alexandrov Sergei , Krasnov Kirill , Speziale Simone
Published: June 2013

Abstract

We propose and study a new first order version of the ghost-free massive gravity. Instead of metrics or tetrads, it uses a connection together with Plebanski’s chiral 2-forms as fundamental variables, rendering the phase space structure similar to that of SU(2) gauge theories. The chiral description simplifies computations of the constraint algebra, and allows us to perform the complete canonical analysis of the system. In particular, we explicitly compute the secondary constraint and carry out the stabilization procedure, thus proving that in general the theory propagates 7 degrees of freedom, consistently with previous claims. Finally, we point out that the description in terms of 2-forms opens the door to an infinite class of ghost-free massive bi-gravity actions. Our results apply directly to Euclidean signature. The reality conditions to be imposed in the Lorentzian signature appear to be more complicated than in the usual gravity case and are left as an open issue.
Dirac gauginos and the 125 GeV Higgs
Authors: Benakli Karim , Goodsell Mark D. , Staub Florian
Published: June 2013

Abstract

We investigate the mass, production and branching ratios of a 125 GeV Higgs in models with Dirac gaugino masses. We give a discussion of naturalness, and describe how deviations from the Standard Model in the key Higgs search channels can be simply obtained. We then perform parameter scans using a SARAH package upgrade, which produces SPheno code that calculates all relevant quantities, including electroweak precision and flavour constraint data, to a level of accuracy previously impossible for this class of models. We study three different variations on the minimal Dirac gaugino extension of the (N)MSSM.
Trockenes Auge bei Kontaktlinsenträgern
Authors: Khaireddin R.
Published: June 2013

Die bisherige Therapiepraxis, Kontaktlinsenträger mit Sicca-Beschwerden einseitig mit Hyaluronsäure-Tränenersatzmitteln zu behandeln, ist fragwürdig. Bei Kontaktlinsenträgern mit Beschwerden des trockenen Auges liegt mehrheitlich eine gestörte Meibom-Drüsen-Funktion vor, die eine Verminderung der Lipidphase des Tränenfilms zur Folge hat. Die damit assoziierte erheblich erhöhte Verdunstung der wässrigen Tränenfilmteile bedingt die messbare Hyperosmolarität des zurückbleibenden ‚‚denaturierten’‘ Tränenfilms. Eine konsekutive inflammatorische Reaktion der Augenoberfläche kann dann zum bekannten Circulus vitiosus des trockenen Auges führen. Um der Dehydrierung durch das Kontaktlinsenmaterial vorzubeugen, sind phosphatfreie, unkonservierte wässrige Tränenersatzmittel sinnvoll. Wird eine verkürzte Tränenfilmaufrisszeit festgestellt, so ist bei der Therapie die Supplementierung der Lipide (z. B. mit Phospholipid-Augenspray) erforderlich. Im Falle einer assoziierten Blepharitis ist die zusätzliche regelmäßige Lidrandhygiene mit einer phospholiposomalen Reinigungslösung therapeutisch sinnvoll und der Lidrandreinigung mit Babyshampoo überlegen.
Maternal Phenylketonuria International Collaborative Study revisited: evaluation of maternal nutritional risk factors besides phenylalanine for fetal congenital heart defects
Authors: Yano Shoji , Moseley Kathryn , Bottiglieri Teodoro , Arning Erland , Azen Colleen
Published: June 2013

Maternal phenylketonuria (MPKU) is known to affect fetal outcome, often being associated with microcephaly and congenital heart defects (CHD) if the maternal diet is not appropriately managed. We hypothesized that other nutrients aside from phenylalanine (Phe) may have significant effects on fetal outcome in MPKU pregnancies. The 416 pregnancies that resulted in live births reported in the Maternal PKU Collaborative Study (MPKUCS) were grouped according to whether or not the offspring were diagnosed with CHD. The groups were compared on first‐trimester values of maternal data, including weight gain, plasma amino acids, protein and Phe intake, and red blood cell (RBC) folate. Patients were also grouped by first‐trimester average blood Phe (≤910 μmol/L and >910 μmol/L) and then divided by total natural protein and medical food intake. The CHD group of 28 offspring had significantly higher blood Phe and lower proline, valine, methionine, isoleucine, leucine, lysine, arginine, and RBC folate. A significantly higher risk for CHD was found in the groups with lower natural protein and medical food intake, regardless of blood Phe levels. Insufficient natural protein and medical food product intake appears to be a risk factor for CHD independent of first‐trimester plasma Phe levels. Low RBC folate and plasma methionine levels in the CHD group may suggest involvement of global DNA hypomethylation.
Functional Outcome of Collagenase Injections Compared with Fasciectomy in Treatment of Dupuytren's Contracture
Authors: Naam Nash H.
Published: June 2013

Background

This study was designed to provide comparative information on the safety and efficacy of injection with collagenase clostridium histolyticum (CCH) and fasciectomy for patients with Dupuytren's contracture (DC).

Methods

A single-center, retrospective, observational, longitudinal chart review was conducted of 25 patients treated with CCH injections and 21 patients undergoing fasciectomy. Patients were assessed at 1 week, monthly for 3 months and then yearly for a minimum of 2 years after treatment for changes in contracture and range of motion, time to return to work/normal activities, patient satisfaction, and Disabilities of Arm, Shoulder and Hand (DASH) score.

Results

Post-procedure follow-up averaged 32 months for the injection group compared with 39 months for fasciectomy group. For the CCH group, the mean postinjection contracture was 3.6° for the metacarpophalangeal and 17.5° for the proximal interphalangeal joints compared with 3.7° and 8.1° in the fasciectomy group, respectively. Patients treated with injections returned to normal activities after a mean of 1.9 days compared with 37.4 days for fasciectomy patients ( p<0.0001). DASH scores for 13 CCH and 15 fasciectomy patients were obtained. The mean DASH score was significantly lower in the injection group in the first 3 months ( p<0.01). At the 2-year follow-up visit, patients were satisfied with their outcomes following either treatment (92 % and 96 % of CCH and fasciectomy patients, respectively).

Conclusion

CCH injections are safe and effective and may be a viable alternative to fasciectomy for treating DC. It also allows earlier return to work and daily activities.
ATF4 activation by the p38MAPK–eIF4E axis mediates apoptosis and autophagy induced by selenite in Jurkat cells
Authors: Jiang Qian , Li Feng , Shi Kejian , Wu Pa , An Jiajia , Yang Yang , Xu Caimin
Published: June 2013

Previous studies have shown that selenite exerts pro‐apoptosis and pro‐autophagy effects and is associated with the activation of ER stress in T‐cell acute lymphoblastic leukemia (T‐ALL). Herein we demonstrate the underlying mechanisms by which the activation of p38MAPK plays essential roles in apoptosis and autophagy and the coordination of cellular metabolic processes during leukemia therapy. MKK3/6‐dependent activation of p38MAPK is required for the phosphorylation of eIF4E, thus initiating the translation of ER stress‐related transcription factor ATF4. Upregulated ATF4 results in the transcriptional initiation of the apoptosis‐related chop gene and autophagy‐related map1lc3b gene, through which selenite links ER stress to apoptosis and autophagy during leukemia treatment. Moreover, autophagy induction enhances cell apoptosis under this condition.
Reactive astrocytes associated with plaques in TgCRND8 mouse brain and in human Alzheimer brain express phosphoprotein enriched in astrocytes (PEA‐15)
Authors: Thomason Lynsie A.M. , Smithson Laura J. , Hazrati Lili-Naz , McLaurin JoAnne , Kawaja Michael D.
Published: June 2013

To identify potential biomarkers associated with Alzheimer's disease (AD)‐like neuropathologies in the murine brain, we conducted proteomic analyses of neocortices from TgCRND8 mice. Here we found that phosphoprotein enriched in astrocytes 15 kDa (PEA‐15) is expressed at higher levels in the neocortical proteomes from 6‐month old TgCRND8 mice, as compared to non‐transgenic mice. Immunostaining for PEA‐15 revealed reactive astrocytes associated with the neocortical amyloid plaques in TgCRND8 mice and in post‐mortem human AD brains. This is the first report of increased phosphoprotein enriched in astrocytes (PEA‐15) expression in reactive astrocytes of an AD mouse model and human AD brains.
Ancient charcoal as a natural archive for paleofire regime and vegetation change in the Mayumbe, Democratic Republic of the Congo
Authors: Hubau Wannes , Van den Bulcke Jan , Kitin Peter , Mees Florias , Baert Geert , Verschuren Dirk , Nsenga Laurent , Van Acker Joris , Beeckman Hans
Published: June 2013

Charcoal was sampled in four soil profiles at the Mayumbe forest boundary (DRC). Five fire events were recorded and 44 charcoal types were identified. One stratified profile yielded charcoal assemblages around 530 cal yr BP and > 43.5 cal ka BP in age. The oldest assemblage precedes the period of recorded anthropogenic burning, illustrating occasional long-term absence of fire but also natural wildfire occurrences within tropical rainforest. No other charcoal assemblages older than 2500 cal yr BP were recorded, perhaps due to bioturbation and colluvial reworking. The recorded paleofires were possibly associated with short-lived climate anomalies. Progressively dry climatic conditions since ca. 4000 cal yr BP onward did not promote paleofire occurrence until increasing seasonality affected vegetation at the end of the third millennium BP, as illustrated by a fire occurring in mature rainforest that persisted until around 2050 cal yr BP. During a drought episode coinciding with the "Medieval Climate Anomaly", mature rainforest was locally replaced by woodland savanna. Charcoal remains from pioneer forest indicate that fire hampered forest regeneration after climatic drought episodes. The presence of pottery shards and oil-palm endocarps associated with two relatively recent paleofires suggests that the effects of climate variability were amplified by human activities.
The Multiple Star η Muscae
Authors: Budding E. , Butland R. , Blackford M.
Published: June 2013

High-resolution spectroscopy of η Mus is combined with literature and new photometry to provide a comprehensive analysis of its components. Our main absolute parameters for the close binary system are M1 and M2 3.34 ± 0.04 M⊙, R1 2.13 ± 0.07 R⊙, R2 2.34 ± 0.10 R⊙; T1 13 000 ± 300, T2 12 600 ± 300, K; and distance 125 ± 10 pc. Our findings update earlier results in a number of respects. We thus confirm that η Mus B is a gravitationally bound companion of the close binary. This relates to the variable γ velocity of the radial velocities of η Mus A. We connect this to the recently discovered member η Mus D, whose orbit we link to new data. We also provide a spectroscopic examination of the Ap star η Mus B, listing over 450 identified lines. We argue that the system is still young, and the apparently anomalous rotation of the close binary’s secondary can be reconciled with its being a physically larger star, still condensing to the zero-age main sequence. Models of young condensing stars permit such expanded states, particularly during the deuterium-burning stage, and our results are in agreement with appropriate low-age models. This possible configuration may make η Mus an important example for testing young star models, formation, and evolution scenarios. This multiple star can be compared with V831 Cen and the general properties related to its membership of the Sco–Cen OB2 association.
Impact of inflammation on the biomarkers of iron status in a cross-sectional survey of Lao women and children
Authors: Knowles Jacqueline , Thurnham David I. , Phengdy Bounthom , Houamboun Keonakhone , Philavong Khamseng , Keomoungkhone Intong , Keovilay Khamhoung
Published: June 2013

Anaemia is prevalent in South East Asia and Fe deficiency (ID) is considered to be the main cause, but the role of subclinical inflammation in the aetiology is uncertain. In the present study, we determined the influence of inflammation on the biomarkers of Fe status in women and children, and herein, we discuss the proportion of anaemia associated with ID. As part of the 2006 Lao People's Democratic Republic (The Lao PDR) National Nutrition Survey, blood collected from 482 young children and 816 non-pregnant women was analysed. Plasma ferritin, transferrin receptor (sTfR), Hb, C-reactive protein (CRP) and α-1-acid glycoprotein (AGP) concentrations were measured. ID was assessed using ferritin concentrations ( < 12 (children) or < 15 (adults) μg/l), sTfR concentrations (>8·3 mg/l) and body Fe stores (BIS < 0). Elevated CRP (>5 mg/l) and/or AGP (>1 g/l) concentrations were used to categorise inflammation status in order to correct the Fe biomarkers for inflammation. Inflammation was present in 14 % of adults and 43 % of children. Anaemia was present in 37·6 % of both women (Hb concentrations < 120 g/l) and children (Hb concentrations < 110 g/l). Correcting ferritin concentrations for inflammation increased the prevalence of ID from 24·3 to 26 % for women and from 18 to 21 % for children (P< 0·001 for both). Ferritin concentrations were more helpful in detecting ID than sTfR concentrations or BIS, but regression analysis found that sTfr concentrations explained more of the variance in Hb concentrations in both women (20 %) and children (17 %) than ferritin concentrations (5 and 1·4 %, respectively). Nevertheless, the total variance in Hb concentrations explained was only 26 and 18 % in women and children, respectively, and other factors may be more important than ID in contributing to anaemia in The Lao PDR.
Numerical Simulations on the Capsizing of Bulk Carriers with Nickel Ores
Authors: Zou Youjia , Shen Chun , Xi Xiangying
Published: June 2013

The liquefaction of nickel ore is widely considered to account for the capsizing and sinking of bulk carriers, but the mechanisms that lead to the incidents still remain uncertain. In this paper, the sloshing motion of fluid with high viscosity in a rectangular tank has been studied; the Level Set Method has been employed to predict the behaviours of fluid sloshing motion under the circumstances of beam seas. In a bid to evaluate the consistency of the numerical solution, a full validation has been performed. The results obtained from the simulations are in good agreement with that from the experiment. The conclusions have also been made that the collapse of the shear resistance of the fluid or increasing heeling moment acquired from the fluid sloshing after liquefaction of the nickel ore may be responsible for the capsizing and sinking of the ships. Hopefully, our conclusions can help ship owners better understand how to take precautions to prevent the ships from capsizing while carrying nickel ore or similar cargos; the results could provide the IMO with the theoretical basis for stipulating new international safe standards for bulk carriers; the numerical methodology can also help engineers to predict sloshing motion of viscous fluids.
Nonpermutation flow line scheduling by ant colony optimization
Authors: Rossi Andrea , Lanzetta Michele
Published: June 2013

A flow line is a conventional manufacturing system where all jobs must be processed on all machines with the same operation sequence. Line buffers allow nonpermutation flowshop scheduling and job sequences to be changed on different machines. A mixed-integer linear programming model for nonpermutation flowshop scheduling and the buffer requirement along with manufacturing implication is proposed. Ant colony optimization based heuristic is evaluated against Taillard's (1993) well-known flowshop benchmark instances, with 20 to 500 jobs to be processed on 5 to 20 machines (stages). Computation experiments show that the proposed algorithm is incumbent to the state-of-the-art ant colony optimization for flowshop with higher job to machine ratios, using the makespan as the optimization criterion.
The Illicit Antiquities Trade as a Transnational Criminal Network: Characterizing and Anticipating Trafficking of Cultural Heritage
Authors: Campbell Peter B.
Published: June 2013

The illicit antiquities trade is composed of a diverse population of participants that gives the appearance of complexity; however, using the network paradigm, a simple underlying structure is revealed based on specific geographical, economic, political, and cultural rules. This article uses a wide range of source material to chart interactions from source to market using a criminal network approach. Interchangeable participants are connected through single interactions to form loosely based networks. These flexible network structures explain the variability observed within the trade, as well as provide the basis behind ongoing debates about the roles of organized crime, terrorism, and the Internet in antiquities trafficking. Finally, a network understanding of trade's organization allows for anticipation, though not necessarily prediction, of antiquities trafficking and offers the opportunity to develop new strategies for combating the trade.
Marxferatu: The Vampire Metaphor as a Tool for Teaching Marx's Critique of Capitalism
Authors: Morrissette Jason J.
Published: June 2013

Although today's undergraduates may not have considered the implications of class struggle, they are generally well-versed in the intricacies of vampire lore. This article outlines how the vampire metaphor can serve as a valuable pedagogical tool for introducing students to fundamental concepts in Marxist thought. As opposed to the supernatural vampires featured in Stoker'sDraculaor Meyer'sTwilightsaga, this approach treats capitalism as a form of economic vampirism—with the capitalist taking on the role of the vampire and the worker relegated to its prey. The article further extends the vampire metaphor and demonstrates how it can be used to teach the Marxist perspectives on class conflict, alienation, and false consciousness.
Environmental factors associated with disordered weight-control behaviours among youth: a systematic review
Authors: Wang Monica L , Peterson Karen E , McCormick Marie C , Austin S Bryn
Published: June 2013

Objective

Environmental factors may be very important in the development of disordered weight-control behaviours (DWCB) among youth, yet no study to date has conducted a review that synthesizes these findings. The purpose of the present study was to systematically review existing literature on environmental influences on DWCB among youth and to identify conceptual and methodological gaps in the literature.

Design

Systematic review.

Setting

Studies were identified through a systematic search using PubMed, PsycINFO, Google Scholar and secondary references. Inclusion criteria included observational studies published in peer-reviewed journals from 1994 to 2012 that examined environmental exposure(s) associated with DWCB among youth.

Subjects

Ninety-three studies, the majority of which utilized a cross-sectional design (75 %;n70), were identified. Longitudinal studies’ follow-up time ranged from 8 months to 10 years.

Results

Parental, peer and media influences have been extensively studied as factors associated with DWCB among youth. Fewer studies have examined behavioural settings (i.e. homes, schools, neighbourhoods) or sectors of influence other than the media on DWCB. No studies utilized multilevel methods to parse out environmental influences on DWCB. Most studies (69 %,n64) did not explicitly utilize a theory or model to guide the research.

Conclusions

Findings indicate that exploring a wider range of environmental influences on DWCB, specifically behavioural settings and sectors of influence, using diverse study samples and multilevel methodology is needed to advance the field and to inform the design of comprehensive prevention programmes that target DWCB and other weight-related behaviours.
Egg consumption and insulin metabolism in the Insulin Resistance Atherosclerosis Study (IRAS)
Authors: Lee Chee-Tin Christine , Liese Angela D , Lorenzo Carlos , Wagenknecht Lynne E , Haffner Steven M , Rewers Marian J , Hanley Anthony J
Published: June 2013

Objective

To examine the association between egg consumption and measures of insulin sensitivity (SI), acute insulin response (AIR) and metabolic clearance rate of insulin (MCRI).

Design

Cross-sectional analysis.

Settings

Egg consumption, categorized as <1/week, 1 to <3/week, 3 to <5/week and ≥5/week, was measured using a validated FFQ. SI, AIR and MCRI were determined from frequently sampled intravenous glucose tolerance tests.

Subjects

Non-diabetic participants (n 949) in the Insulin Resistance Atherosclerosis Study (IRAS).

Results

Egg consumption was inversely associated with SI and MCRI, and positively associated with fasting insulin in regression models adjusted for demographic, socio-economic, lifestyle and dietary factors (β = −0·22, 95 % CI −0·38, −0·045, P = 0·05 for SI; β = −0·20, 95 % CI −0·34, −0·055, P = 0·005 for MCRI; β = 0·35, 95 % CI 0·15, 0·54, P = 0·002 for fasting insulin; all P values for linear trend). These associations remained significant after additionally adjusting for energy intake or dietary saturated fat, although dietary cholesterol and BMI attenuated these associations to non-significance. Egg consumption was not associated with AIR.

Conclusions

Dietary cholesterol and BMI appear to mediate the inverse association of egg consumption with insulin sensitivity and clearance. Alternatively, egg consumption may be clustered with other dietary behaviours which increase BMI, hence negatively impacting on insulin sensitivity and clearance.
Public health policy to redress iodine insufficiency in pregnant women may widen sociodemographic disparities
Authors: Mallard Simonette R , Houghton Lisa A
Published: June 2013

Objective

To evaluate the impact of a mandatory bread fortification programme on estimated iodine intakes of childbearing women and to describe the extent to which uptake of a maternal iodine supplement recommendation is associated with sociodemographic characteristics.

Design

A postpartum survey was conducted using a self-administered questionnaire. Details on pre- and post-conceptional supplement use, bread intake, iodized salt use and maternal sociodemographic and obstetric characteristics were obtained.

Setting

Eleven maternity wards and hospitals located across New Zealand.

Subjects

Seven hundred and twenty-three postpartum New Zealand women.

Results

Mean iodine intake from fortified bread was 37 μg/d prior to conception. Younger women, women with higher parity, single women and those with unplanned pregnancies were less likely to meet the pregnancy Estimated Average Requirement (EAR) for iodine (allP≤ 0·022). Although not statistically significant for all months of pregnancy, women with less education and income were less likely to meet the EAR (P≤ 0·11 andP≤ 0·2 for all months, respectively) and indigenous Māori women and Pacific women were less likely than New Zealand Europeans to meet the EAR (P≤ 0·17 andP≤ 0·051 for all months, respectively). During pregnancy, iodine-containing supplement uptake at the recommended level (150 μg/d) was non-uniform across sociodemographic subgroups, with the most disadvantaged women benefiting the least from this public health policy.

Conclusions

The disparities in supplement uptake noted here highlight the need for prioritizing further efforts towards universal salt iodization, such as the mandatory fortification of additional processed foods with iodized salt.
Perturbations to aquatic photosynthesis due to high-energy cosmic ray induced muon flux in the extragalactic shock model
Authors: Rodriguez Lien , Cardenas Rolando , Rodriguez Oscar
Published: June 2013

We modify a mathematical model of photosynthesis to quantify the perturbations that high energy muons could make on aquatic primary productivity. Then, we apply this in the context of the extragalactic shock model, according to which Earth receives an enhanced dose of high-energy cosmic rays when it is at the galactic north. We obtain considerable reduction in the photosynthesis rates, consistent with potential drops in biodiversity.