bluuebunny/crossref_metadata_2025 huggingface dataset:
A step-defined sedentary lifestyle index: <5000 steps/day
Authors: Tudor-Locke Catrine , Craig Cora L. , Thyfault John P. , Spence John C.
Published: November 2012

Step counting (using pedometers or accelerometers) is widely accepted by researchers, practitioners, and the general public. Given the mounting evidence of the link between low steps/day and time spent in sedentary behaviours, how few steps/day some populations actually perform, and the growing interest in the potentially deleterious effects of excessive sedentary behaviours on health, an emerging question is “How many steps/day are too few?” This review examines the utility, appropriateness, and limitations of using a reoccurring candidate for a step-defined sedentary lifestyle index: <5000 steps/day. Adults taking <5000 steps/day are more likely to have a lower household income and be female, older, of African-American vs. European-American heritage, a current vs. never smoker, and (or) living with chronic disease and (or) disability. Little is known about how contextual factors (e.g., built environment) foster such low levels of step-defined physical activity. Unfavorable indicators of body composition and cardiometabolic risk have been consistently associated with taking <5000 steps/day. The acute transition (3–14 days) of healthy active young people from higher (>10 000) to lower (<5000 or as low as 1500) daily step counts induces reduced insulin sensitivity and glycemic control, increased adiposity, and other negative changes in health parameters. Although few alternative values have been considered, the continued use of <5000 steps/day as a step-defined sedentary lifestyle index for adults is appropriate for researchers and practitioners and for communicating with the general public. There is little evidence to advocate any specific value indicative of a step-defined sedentary lifestyle index in children and adolescents.
Patterns and mechanisms of fluvial sediment flux and accumulation in two subarctic fjords: Nachvak and Saglek Fjords, Nunatsiavut, Canada
Authors: Bentley Samuel J. , Kahlmeyer Elisabeth
Published: November 2012

Recent marine sedimentary deposits and river discharge in two subarctic fjords in Nunatsiavut (Northern Labrador, Canada) have been studied to elucidate patterns and mechanisms of fluvial sediment transfer and accumulation in the fjords, to further our understanding of the longer-term sedimentary record. Multibeam and sub-bottom acoustic data and sediment cores were collected in Nachvak and Saglek fjords, within Canada’s Torngat Mountains National Park, as part of the most extensive study of the park’s marine resources to date. Cores were subsampled for X-radiography, grain size, and 210Pb/137Cs geochronology. Muddy basin sediments within each fjord are bioturbated, indicating circulation of oxygenated bottom water. Depositional fluxes and inventories of 210Pb indicate efficient marine scavenging of 210Pb by fine suspended sediments. In Nachvak Fjord, with small rivers and steep, presently glaciated catchments, postglacial and recent sediment accumulation rates are similar, implying relatively constant sedimentation over time. In Saglek Fjord, fed by larger rivers with more extensive catchments that lack glaciers, recent sediment accumulation is more rapid than that averaged over postglacial time. Present mass accumulation rates for the Nachvak Fjord basin are on average 39 000 t·year–1 for the entire basin, and for Saglek 43 000 t·year–1 for the entire basin, with sediment-gravity flows being one likely mechanism for sediment delivery to deep basins. Results collectively suggest that both marine basins are excellent natural sediment traps. Comparison of accumulation rates from 137Cs and 210Pb suggest that sediment fluxes to Nachvak Fjord may have decreased slightly over the past ∼130 years.
MEASUREMENTS AND INFORMATION IN SPIN FOAM MODELS
Authors: GARCÍA-ISLAS J. MANUEL
Published: November 2012

In the three-dimensional spin foam model of quantum gravity with a cosmological constant, there exists a set of observables associated with spin network graphs. A set of probabilities is calculated from these observables, and hence the associated Shannon entropy can be defined. We present the Shannon entropy associated with these observables and find some interesting bounded inequalities. The problem relates measurements, entropy and information theory in a simple way which we explain.
PLANAR MASSLESS FERMIONS IN COULOMB AND AHARONOV–BOHM POTENTIALS
Authors: KHALILOV V. R. , LEE K. E.
Published: November 2012

Solutions to the Dirac equation are constructed for a massless charged fermion in Coulomb and Aharonov–Bohm (AB) potentials in 2+1 dimensions. The Dirac Hamiltonian on this background is singular and needs a one-parameter self-adjoint extension, which can be given in terms of self-adjoint boundary conditions. We show that the virtual (quasistationary) bound states emerge in the presence of an attractive Coulomb potential when the so-called effective charges become overcritical and discuss a restructuring of the vacuum of the quantum electrodynamics when the virtual bound states emerge. We derive equations, which determine the energies and lifetimes of virtual bound states, find solutions of obtained equations for some values of parameters as well as analyze the local density of states (LDOS) as a function of energy in the presence of Coulomb and AB potentials.
FIRST PRINCIPLES STUDY ON ELECTRONIC AND OPTICAL PROPERTIES OF Al-DOPED γ-Ge3N4
Authors: DING Y. C. , XIANG A. P. , ZHU X. H. , LUO J. , HU X. F.
Published: November 2012

First principles study of the structural, electronic and optical properties of Al -doped γ- Ge 3 N 4 with different concentration has been reported using the pseudo-potential plane wave method within the generalized gradient approximation (GGA). The binding energy and the formation energy suggest that Aluminum (Al) impurities prefer to substitute Ge at octahedral sites. Different doping concentrations are considered and the corresponding density of states (DOS) are analyzed. Calculated DOS indicates that there are holes in the top of the valance band after doping, meaning a p-type doping. We study the complex dielectric function, the absorption coefficient, and the electron energy loss spectra. It is demonstrated that for the low Al concentration, the material exhibits the dielectric behavior and for the high Al concentration, the material has possibilities to exhibit some metallic behavior. The γ- Ge 3 N 4 doped with Al has a much higher static dielectric constant than undoped γ- Ge 3 N 4, implying its potential applications in electronics and optics.
CORRELATIONS IN QUANTUM PHYSICS
Authors: DORNER ROSS , VEDRAL VLATKO
Published: November 2012

We provide a historical perspective of how the notion of correlations has evolved within quantum physics. We begin by reviewing Shannon's information theory and its first application in quantum physics, due to Everett, in explaining the information conveyed during a quantum measurement. This naturally leads us to Lindblad's information theoretic analysis of quantum measurements and his emphasis of the difference between the classical and quantum mutual information. After briefly summarizing the quantification of entanglement using these ideas, we arrive at the concept of quantum discord, which naturally captures the boundary between entanglement and classical correlations. Finally we discuss possible links between discord, which the generation of correlations in thermodynamic transformations of coupled harmonic oscillators.
TRANSPORT OF QUANTUM CORRELATIONS ACROSS A SPIN CHAIN
Authors: APOLLARO TONY J. G. , LORENZO SALVATORE , PLASTINA FRANCESCO
Published: November 2012

Some of the recent developments concerning the propagation of quantum correlations across spin channels are reviewed. In particular, we focus on the improvement of the transport efficiency obtained by the manipulation of few energy parameters (either end-bond strengths or local magnetic fields) near the sending and receiving sites. We give a physically insightful description of various such schemes and discuss the transfer of both entanglement and of quantum discord.
A NOVEL SUPERVISED STRUCTURE DICTIONARY LEARNING FOR CLASSIFICATION BASED ON SPARSE REPRESENTATION
Authors: TANG XIN , WANG PATRICK S. , FENG GUOCAN
Published: November 2012

Sparse representation based classification has led to interesting image recognition results, while the dictionary used for sparse coding plays a key role in it. This paper presents a novel supervised structure dictionary learning (SSDL) algorithm to learn a discriminative and block structure dictionary. We associate label information with each dictionary item and make each class-specific sub-dictionary in the whole structured dictionary have good representation ability to the training samples from the associated class. More specifically, we learn a structured dictionary and a multiclass classifier simultaneously. Adding an inhomogeneous representation term to the objective function and considering the independence of the class-specific sub-dictionaries improve the discrimination capabilities of the sparse coordinates. An iteratively optimization method be proposed to solving the new formulation. Experimental results on four face databases demonstrate that our algorithm outperforms recently proposed competing sparse coding methods.
FROZEN ORBITS AROUND EUROPA
Authors: CARVALHO J. P. S. , MOURÃO D. C. , ELIPE A. , DE MORAES R. VILHENA , PRADO A. F. B. A.
Published: November 2012

Low-altitude, near-polar orbits are very desirable for scientific missions to study the natural satellites of the planets of the Solar System, such as Europa, that is one of the natural satellites of Jupiter. The problem is analyzed considering that an artificial satellite is orbiting Europa and that this spacecraft is perturbed by the nonuniform distribution of mass of the planetary satellite (J2, J3, C22) and by the gravitational attraction of the third-body. We present an analytical theory using the averaged model and applications were done by performing numerical integrations of the analytical equations developed. Using the averaged method, several frozen orbits were obtained. Some of them has low inclination, low altitude and long lifetime. Numerical simulations are performed using the software Mercury, to compare the results obtained using the analytical theory.
THE EFFECT OF WEAK DISSIPATION IN TWO-DIMENSIONAL MAPPING
Authors: DE OLIVEIRA JULIANO A. , LEONEL EDSON D.
Published: November 2012

The influence of weak dissipation and its consequences in a two-dimensional mapping are studied. The mapping is parametrized by an exponent γ in one of the dynamical variables and by a parameter δ which denotes the amount of the dissipation. It is shown that for different values of γ the structure of the phase space of the nondissipative model is replaced by a large number of attractors. The approach to the attracting fixed point is characterized both analytically and numerically. The attracting fixed point exhibits a very complicated basin of attraction.
CRITICAL EXPONENTS AND SCALING PROPERTIES FOR THE CHAOTIC DYNAMICS OF A PARTICLE IN A TIME-DEPENDENT POTENTIAL BARRIER
Authors: DA COSTA DIOGO RICARDO , LIVORATI ANDRÉ LUÍS PRANDO , LEONEL EDSON D.
Published: November 2012

Some scaling properties of the chaotic sea for a particle confined inside an infinitely deep potential box containing a time varying barrier are studied. The dynamics of the particle is described by a two-dimensional, nonlinear and area-preserving mapping for the variables energy of the particle and time. The phase space of the model exhibits a mixed structure with Kolmogorov–Arnold–Moser islands, chaotic seas and invariant spanning curves limiting the chaotic orbits. Average properties of the chaotic sea including the first momenta and the deviation of the second momenta are obtained as a function of: (i) number of iterations (n), and (ii) time (t). By the use of scaling arguments, critical exponents for the ensemble average of the first momenta are obtained and compared for both cases (i) and (ii). Scaling invariance of the average properties for the chaotic sea is obtained as a function of the control parameters that describe the model.
HYBRID PINNING CONTROL FOR COMPLEX NETWORKS
Authors: TURCI LUIZ FELIPE R. , MACAU ELBERT E. N.
Published: November 2012

In this work, we present two different hybrid pinning strategies to synchronize a complex network of identical agents into a known desired solution. The first strategy is the chaos control hybrid pinning in which pinning synchronization control and chaos control are merged. The second strategy is the nonidentical reference hybrid pinning, in which the pinning reference dynamical behavior is different from network nodes dynamical behavior.
AN INITIAL STUDY OF THE FLOW AROUND AN AEROFOIL AT HIGH REYNOLDS NUMBERS USING CONTINUATION
Authors: WALES C. , GAITONDE A. , JONES D.
Published: November 2012

Nonlinearities are an important feature of high Reynolds numbers flows about aircraft. Standard time stepping schemes, used in computational fluid dynamics simulations, are unable to capture the whole solution space, breaking down in the region of bifurcations. The extension of continuation techniques to such flows is therefore attractive. CFD schemes yield large systems of equations and the associated difficulties of applying continuation methods to such large systems need to be overcome. Whilst previous studies of fluids using continuation have been published, these are mainly limited to much lower Reynolds numbers. In high Reynolds number flows, inertial forces dominate and turbulence must be modeled. This study has shown that continuation can be used effectively for high Reynolds number flows demonstrated through the presentation of a number of test cases.
CHAOS ON ONE-DIMENSIONAL COMPACT METRIC SPACES
Authors: KOČAN ZDENĚK
Published: November 2012

We consider various kinds of chaotic behavior of continuous maps on compact metric spaces: the positivity of topological entropy, the existence of a horseshoe, the existence of a homoclinic trajectory (or perhaps, an eventually periodic homoclinic trajectory), three levels of Li–Yorke chaos, three levels of ω-chaos and distributional chaos of type 1. The relations between these properties are known when the space is an interval. We survey the known results in the case of trees, graphs and dendrites.
SIGN-CHANGING SOLUTIONS FOR AN ASYMPTOTICALLY p-LINEAR p-LAPLACIAN EQUATION IN ℝN
Authors: LIU XIANGQING , GUO YUXIA
Published: November 2012

In this paper, we study the existence of sign-changing solutions for the p-Laplacian equation [Formula: see text] where λ is a positive parameter and the nonlinear term f is superlinear at zero and asymptotically p-linear at infinity.
BEST CONSTANTS AND POHOZAEV IDENTITY FOR HARDY–SOBOLEV-TYPE OPERATORS
Authors: ADIMURTHI
Published: November 2012

This paper is threefold. Firstly, we reformulate the definition of the norm induced by the Hardy inequality (see [J. L. Vázquez and N. B. Zographopoulos, Functional aspects of the Hardy inequality. Appearance of a hidden energy, preprint (2011); http://arxiv. org/abs/1102.5661]) to more general elliptic and sub-elliptic Hardy–Sobolev-type operators. Secondly, we derive optimal inequalities (see [C. Cowan, Optimal inequalities for general elliptic operator with improvement, Commun. Pure Appl. Anal.9(1) (2010) 109–140; N. Ghoussoub and A. Moradifam, Bessel pairs and optimal Hardy and Hardy–Rellich inequalities, Math. Ann.349(1) (2010) 1–57 (electronic)]) for multiparticle systems in ℝN and Heisenberg group. In particular, we provide a direct proof of an optimal inequality with multipolar singularities shown in [R. Bossi, J. Dolbeault and M. J. Esteban, Estimates for the optimal constants in multipolar Hardy inequalities for Schrödinger and Dirac operators, Commun. Pure Appl. Anal.7(3) (2008) 533–562]. Finally, we prove an approximation lemma which allows to show that the domain of the Dirichlet–Laplace operator is dense in the domain of the corresponding Hardy operators. As a consequence, in some particular cases, we justify the Pohozaev-type identity for such operators.
THE FUNDAMENTAL GROUP OF G-MANIFOLDS
Authors: LI HUI
Published: November 2012

Let G be a connected compact Lie group, and let M be a connected Hamiltonian G-manifold with equivariant moment map ϕ. We prove that if there is a simply connected orbit G ⋅ x, then π1(M) ≅ π1(M/G); if additionally ϕ is proper, then π1(M) ≅ π1 (ϕ-1(G⋅a)), where a = ϕ(x). We also prove that if a maximal torus of G has a fixed point x, then π1(M) ≅ π1(M/K), where K is any connected subgroup of G; if additionally ϕ is proper, then π1(M) ≅ π1(ϕ-1(G⋅a)) ≅ π1(ϕ-1(a)), where a = ϕ(x). Furthermore, we prove that if ϕ is proper, then [Formula: see text] for all a ∈ ϕ(M), where [Formula: see text] is any connected subgroup of G which contains the identity component of each stabilizer group; in particular, π1(M/G) ≅ π1(ϕ-1(G⋅a)/G) for all a ∈ ϕ(M).
PERIODIC SOLUTIONS FOR SINGULAR PERTURBATIONS OF THE SINGULAR ϕ-LAPLACIAN OPERATOR
Authors: BEREANU CRISTIAN , GHEORGHE DANA , ZAMORA MANUEL
Published: November 2012

In this paper, using Leray–Schauder degree arguments and the method of lower and upper solutions, we give existence and multiplicity results for periodic problems with singular nonlinearities of the type [Formula: see text] where r, n, e : [0, T] → ℝ are continuous functions and λ > 0. We also consider some singular nonlinearities arising in nonlinear elasticity or of Rayleigh–Plesset type.
AN INEQUALITY BY GIANAZZA, SAVARÉ AND TOSCANI AND ITS APPLICATIONS TO THE VISCOUS QUANTUM EULER MODEL
Authors: XU XIANGSHENG
Published: November 2012

In this paper we present a simplified version of a coercivity inequality due to Gianazza, Savaré, and Toscani [The Wasserstein gradient flow of the Fisher information and the quantum drift-diffusion equation, Arch. Ration. Mech. Anal.194 (2009) 133–220]. Then we use the inequality to construct a weak solution to the initial-boundary value problem for the viscous quantum Euler model.
PRIME IRREDUCIBLE MATRIX REPRESENTATIONS OF A LEFT AMPLE SEMIGROUP
Authors: Guo Xiaojiang , Shum K. P.
Published: November 2012

In this paper, we prove that any prime irreducible representation of a left ample semigroup being eventually regular can be constructed by some irreducible representation of some groups. This result enriches and extends the related results of W. D. Munn on prime irreducible representations of an inverse semigroup.
ARBITRARINESS OF JORDAN STRUCTURE IN FACTORIZATION: THE GEOMETRIC MULTIPLICITY RESTRICTION AND THE 3 × 3 CASE
Authors: Johnson Charles R. , Lewis Drew , Zhang YuLin
Published: November 2012

For the problem of which Jordan forms are possible for n × n complex matrices A, B and C, when A = BC, geometric multiplicity restrictions are given for the eigenvalues of the three matrices. Together with the obvious determinantal condition on the eigenvalues, these necessary conditions are shown to be sufficient for the problem when n < 4, but not for n ≥ 4. Some basic observations about the problem are given in the process.
IF-AUTOMORPHISMS OF A FREE SOLVABLE Sp-PERMUTABLE ALGEBRA OF A FINITE RANK OVER A LEFT CANCELLATIVE MONOID ARE PSEUDO-TAME
Authors: Zhdanovich P. B.
Published: November 2012

Consider a variety V of acts over a left cancellative monoid S that have a ternary Maltsev operation p(〈p, S〉- algebras ). Using the Magnus–Artamonov representation, the construction of the free Abelian extension of an arbitrary V-algebra was obtained and explored by the author. In the present article we prove that each IF-automorphism of a free k-step solvable V-algebra of a finite rank (k > 1) is pseudo-tame, i.e. it is presented as a product of elementary automorphisms of a special module over a ring with several objects.
New understanding of deep unsaturated zone controls on recharge in the Chalk: a case study near Patcham, SE England
Authors: Rutter H. K. , Cooper J. D. , Pope D. , Smith M.
Published: November 2012

This paper describes data obtained from tensiometers installed through 60 m of the unsaturated zone of a site situated on the Chalk aquifer of southern England. The data are interpreted together with consideration of previous work on unsaturated zone processes. The data show that, at the North Heath Barn site near Patcham (West Sussex, UK), matric potentials at many depths remain high throughout the year, and therefore the potential for fracture flow to occur remains high throughout the year. The high matric potentials support earlier closed-circuit TV surveys that indicated that wet borehole walls occurred throughout the year at some horizons. Rapid bypass flow (taken to mean significant fracture flow that is sufficient to cause a water level rise) occurs relatively frequently through winter, and there is a characteristic sequence of events leading to a water level rise. Although, during the summer, effective precipitation ceased (i.e. precipitation was exceeded by evapotranspiration) at the surface, beyond the root zone, downward drainage of water through the unsaturated zone occurred throughout the year, with recharge occurring at the water table. The recession of water levels in the spring reflected the fact that recharge at the water table was less than discharge through saturated zone flow, rather than a cessation in drainage altogether. This is the first time continuing drainage through the deep unsaturated zone has been directly observed, although it has been inferred for many years.
Measurements of spontaneous potential in chalk with application to aquifer characterization in the southern UK
Authors: Jackson M. D. , Butler A. P. , Vinogradov J.
Published: November 2012

We report the first measured values of the streaming potential coupling coefficient in chalk samples saturated with natural groundwater, and preliminary field measurements of the spontaneous potential (SP), at both ambient and pumped conditions, at a test site in the Berkshire Chalk aquifer in the southern UK. The ultimate aim of the work is to use measurements of SP, in conjunction with borehole data, to characterize groundwater flow and aquifer properties. Laboratory measurements yield a value of the streaming potential coupling coefficient of −60 ± 4 mV MPa
−1
and a corresponding zeta potential of −13 ± 1 mV. A negative zeta potential contrasts with previous published open-system measurements on artificial calcite, and may reflect the presence of organic material in the natural chalk samples or HCO
3
and SO
4
ions in the groundwater. Field measurements at ambient conditions show temporal variations in SP consistent with flow processes within the aquifer, but no coherent spatial variations. Measurements during water abstraction demonstrate that voltages at the ground surface and in monitoring boreholes become more positive during pressure drawdown and more negative during pressure build-up, consistent with the negative values of streaming potential coupling coefficient and zeta potential observed in the laboratory. Moreover, the magnitude of the change in voltage is similar to that estimated using the laboratory value of the coupling coefficient. Our results suggest that measurements of SP may make a valuable contribution to characterizing groundwater flow in the UK Chalk aquifer.
Human interference on soft cliff retreat: examples from Christchurch Bay, UK
Authors: Brown S. , Barton M. E. , Nicholls R. J.
Published: November 2012

Human interference in soft coastal cliff retreat causes problems worldwide. Building defences alters the sediment budget, frequently causing a sediment deficit down-drift resulting in increased retreat rates. Subsequently, undefended shorelines become set back from protection works, often causing excessive and unexpected land and infrastructure loss, prompting defence extensions. Down-drift of groynes, this is known as the terminal groyne effect. From case studies, this paper determines the effects of human interference on soft cliffs, and investigates excessive land loss and likely future coastal response.

Using 10.5 km of soft cliffs in Christchurch Bay, UK as a study region, a historical shoreline analysis from the mid 19th century to the present day was undertaken. Detailed analysis was conducted at three case study sites to determine whether retreat rates had increased down-drift after the construction of protection works. After defence construction, increased retreat occurred at all three sites, albeit for only a few hundred metres down-drift, as propagation was limited owing to a headland or large sediment volumes. Set-backs can lead to artificial headland formation, making the coast more challenging and costly to defend. Shoreline management plans advocating protection or realignment should take account of natural features to enhance engineering design and reduce excess land loss.
Field determination of shallow soil thermal conductivity using a short-duration needle probe test
Authors: King W. , Banks D. , Findlay J.
Published: November 2012

The thermal conductivity of shallow subsoil, one of the important input parameters in the design of a horizontal closed-loop ground heat exchange system, can be derived by means of a thermal needle probe survey. The probe is mounted on a 1.5 m handle, allowing short-duration (10 min) thermal response tests to be carried out at various locations and depths within a land area designated for such a heat exchanger. At two study sites in Central England, a minimum of 12–16 such determinations were required to obtain a stable estimate of bulk thermal conductivity (based on the geometric mean of single measurements), although one cannot necessarily assume that this minimum requirement would be generally valid at all sites. At the two sites, the method proved relatively rapid and able to deliver a value of geometric mean thermal conductivity with a typical uncertainty of the order of 15%.
Petrophysical and durability tests on sedimentary stones to evaluate their quality as building materials
Authors: Cultrone G. , Luque A. , Sebastián E.
Published: November 2012

Six types of sedimentary stone (four bioclastic calcarenites, one calcitic sandstone and one calcitic dolostone) commonly used as building materials were studied from a petrophysical point of view and their durability was evaluated. The following analytical techniques were used: X-ray diffraction, polarizing optical microscopy, hydric tests, mercury intrusion porosimetry, ultrasound, salt crystallization cycles, freeze–thaw cycles and colorimetry. The hydric behaviour of the stones is affected by their different textures. The most compact stone absorbs less water compared with the other samples and has the lowest open porosity; however, more porous and less compact stones achieved better results in terms of the degree of pore interconnection and the drying rate. All the stones have unimodal pore size distribution and most pores had radii of 10 μm or less. Accelerated ageing tests caused some changes in the colour of stones and, above all, the loss of fragments, especially during salt crystallization cycles. The main causes of decay were the different mineralogy between the grains and the matrix in the sandstone and a strong anisotropy owing to the presence of sedimentary planes in one calcarenite. On the basis of our results we then ranked the stones according to their quality as building materials.
The hydrochemistry of a Chalk aquifer during recovery from drought
Authors: Darling W. G. , Gooddy D. C. , Morris B. L. , Peach D. W.
Published: November 2012

Chalk groundwater levels typically decline markedly in response to drought, and rebound strongly when the drought breaks. Chalk streams, largely groundwater-fed, are of ecological importance but little research has been conducted on possible water-quality effects accompanying fluctuations in groundwater level. This study monitored springs, boreholes and surface water in the Pang and Lambourn catchments in southern England during a major recovery in 2006–2008. Hydrochemistry, stable isotopes and age indicators were used to characterize the waters. Perennial springs showed little change in water quality over the monitoring period, and even seasonal springs soon became consistent in their hydrochemistry. A similar lack of change was observed in borehole waters and in the River Lambourn. Stable isotopes demonstrated the high degree of damping relative to rainfall inputs, and residence time indicators showed that Chalk groundwater is basically a mixture with an ‘old’ (pre-1950s) component of ≥50%. This being the case, any water quality changes owing to water level fluctuations would inevitably become diluted. Therefore, although future climate predictions for southern Britain include greater extremes in rainfall and temperature, and consequently water level changes of greater amplitude, the buffering effect of the Chalk aquifer should protect the quality of Chalk springs and streams.
Analogs of bardoxolone methyl worsen diabetic nephropathy in rats with additional adverse effects
Authors: Zoja Carla , Corna Daniela , Nava Valeria , Locatelli Monica , Abbate Mauro , Gaspari Flavio , Carrara Fabiola , Sangalli Fabio , Remuzzi Giuseppe , Benigni Ariela
Published: November 2012

Bardoxolone methyl is an antioxidant inflammation modulator acting through induction of Keap1-Nrf2 pathway. Results from a recent phase IIb clinical trial reported that bardoxolone methyl was associated with improvement in the estimated glomerular filtration rate in patients with advanced chronic kidney disease and Type 2 diabetes. However, increases in albuminuria, serum transaminase, and frequency of adverse events were noted. We studied the effect of 3-mo treatment with RTA 405, a synthetic triterpenoid analog of bardoxolone methyl in Zucker diabetic fatty rats with overt Type 2 diabetes. Rats were treated from 3 mo of age with vehicle, RTA 405, ramipril, or RTA 405 plus ramipril. RTA 405 caused severe changes in food intake and diuresis with decline in body weight, worsening of dyslipidemia, and increase in blood pressure. Early elevation in serum transaminase was followed by liver injury. RTA 405 worsened proteinuria, glomerulosclerosis, and tubular damage. Ramipril was renoprotective, but when given with RTA 405 it was not able to limit its worsening effects. These data could be due to degradation products in the drug substance used, as disclosed by the company once the study was concluded. To overcome such a drawback, the company offered to test dh404, a variant of RTA 405, in Zucker diabetic fatty rats. The dh404 did not display beneficial effects on proteinuria, glomerulosclerosis, and interstitial inflammation. Rather, kidneys from three rats receiving dh404 showed the presence of a granulomatous and inflammatory process reminiscent of a pseudotumor. Altogether these data raise serious concerns on the use of bardoxolone analogs in Type 2 diabetic nephropathy.
Cardiac baroreflex function and dynamic cerebral autoregulation in elderly Masters athletes
Authors: Aengevaeren Vincent L. , Claassen Jurgen A. H. R. , Levine Benjamin D. , Zhang Rong
Published: November 2012

Cerebral blood flow (CBF) is stably maintained through the combined effects of blood pressure (BP) regulation and cerebral autoregulation. Previous studies suggest that aerobic exercise training improves cardiac baroreflex function and beneficially affects BP regulation, but may negatively affect cerebral autoregulation. The purpose of this study was to reveal the impact of lifelong exercise on cardiac baroreflex function and dynamic cerebral autoregulation (CA) in older adults. Eleven Masters athletes (MA) (8 men, 3 women; mean age 73 ± 6 yr; aerobic training >15 yr) and 12 healthy sedentary elderly (SE) (7 men, 5 women; mean age 71 ± 6 yr) participated in this study. BP, CBF velocity (CBFV), and heart rate were measured during resting conditions and repeated sit-stand maneuvers to enhance BP variability. Baroreflex gain was assessed using transfer function analysis of spontaneous changes in systolic BP and R-R interval in the low frequency range (0.05–0.15 Hz). Dynamic CA was assessed during sit-stand–induced changes in mean BP and CBFV at 0.05 Hz (10 s sit, 10 s stand). Cardiac baroreflex gain was more than doubled in MA compared with SE (MA, 7.69 ± 7.95; SE, 3.18 ± 1.29 ms/mmHg; P = 0.018). However, dynamic CA was similar in the two groups (normalized gain: MA, 1.50 ± 0.56; SE, 1.56 ± 0.42% CBFV/mmHg; P = 0.792). These findings suggest that lifelong exercise improves cardiac baroreflex function, but does not alter dynamic CA. Thus, beneficial effects of exercise training on BP regulation can be achieved in older adults without compromising dynamic regulation of CBF.
Modulation of the axon-reflex response to local heat by reactive oxygen species in subjects with chronic fatigue syndrome
Authors: Medow Marvin S. , Aggarwal Arun , Baugham Ila , Messer Zachary , Stewart Julian M.
Published: November 2012

Local cutaneous heating causes vasodilation as an initial first peak, a nadir, and increase to plateau. Reactive oxygen species (ROS) modulate the heat plateau in healthy controls. The initial peak, due to C-fiber nociceptor-mediated axon reflexes, is blunted with local anesthetics and may serve as a surrogate for the cutaneous response to peripheral heat. Chronic fatigue syndrome (CFS) subjects report increased perception of pain. To determine the role of ROS in this neurally mediated response, we evaluated changes in cutaneous blood flow from local heat in nine CFS subjects (16–22 yr) compared with eight healthy controls (18–26 yr). We heated skin to 42°C and measured local blood flow as a percentage of maximum cutaneous vascular conductance (%CVCmax). Although CFS subjects had significantly lower baseline flow [8.75 ± 0.56 vs. 12.27 ± 1.07 (%CVCmax, CFS vs. control)], there were no differences between groups to local heat. We then remeasured this with apocynin to inhibit NADPH oxidase, allopurinol to inhibit xanthine oxidase, tempol to inhibit superoxide, and ebselen to reduce H2O2. Apocynin significantly increased baseline blood flow (before heat, 14.91 ± 2.21 vs. 8.75 ± 1.66) and the first heat peak (69.33 ± 3.36 vs. 59.75 ± 2.75). Allopurinol and ebselen only enhanced the first heat peaks (71.55 ± 2.48 vs. 61.72 ± 2.01 and 76.55 ± 5.21 vs. 58.56 ± 3.66, respectively). Tempol had no effect on local heating. None of these agents changed the response to local heat in control subjects. Thus the response to heat may be altered by local levels of ROS, particularly H2O2 in CFS subjects, and may be related to their hyperesthesia/hyperalgesia.
Automated image analysis of skeletal muscle fiber cross-sectional area
Authors: Mula Jyothi , Lee Jonah D. , Liu Fujun , Yang Lin , Peterson Charlotte A.
Published: November 2012

Morphological characteristics of muscle fibers, such as fiber size, are critical factors that determine the health and function of the muscle. However, at this time, quantification of muscle fiber cross-sectional area is still a manual or, at best, a semiautomated process. This process is labor intensive, time consuming, and prone to errors, leading to high interobserver variability. We have developed and validated an automatic image segmentation algorithm and compared it directly with commercially available semiautomatic software currently considered state of the art. The proposed automatic segmentation algorithm was evaluated against a semiautomatic method with manual annotation using 35 randomly selected cross-sectional muscle histochemical images. The proposed algorithm begins with ridge detection to enhance the muscle fiber boundaries, followed by robust seed detection based on concave area identification to find initial seeds for muscle fibers. The final muscle fiber boundaries are automatically delineated using a gradient vector flow deformable model. Our automatic approach is accurate and represents a significant advancement in efficiency; quantification of fiber area in muscle cross sections was reduced from 25–40 min/image to 15 s/image, while accommodating common quantification obstacles including morphological variation (e.g., heterogeneity in fiber size and fibrosis) and technical artifacts (e.g., processing defects and poor staining quality). Automatic quantification of muscle fiber cross-sectional area using the proposed method is a powerful tool that will increase sensitivity, objectivity, and efficiency in measuring muscle adaptation.
Failure of normal development of central drive to ankle dorsiflexors relates to gait deficits in children with cerebral palsy
Authors: Petersen Tue Hvass , Farmer Simon F. , Kliim-Due Mette , Nielsen Jens Bo
Published: November 2012

Neurophysiological markers of the central control of gait in children with cerebral palsy (CP) are used to assess developmental response to therapy. We measured the central common drive to a leg muscle in children with CP. We recorded electromyograms (EMGs) from the tibialis anterior (TA) muscle of 40 children with hemiplegic CP and 42 typically developing age-matched controls during static dorsiflexion of the ankle and during the swing phase of treadmill walking. The common drive to TA motoneurons was identified through time- and frequency-domain cross-correlation methods. In control subjects, the common drive consists of frequencies between 1 and 60 Hz with peaks at beta (15–25 Hz) and gamma (30–45 Hz) frequencies known to be caused by activity within sensorimotor cortex networks: this drive to motoneurons strengthens during childhood. Similar to this drive in control subjects, this drive to the least affected TA in the CP children tended to strengthen with age, although compared with that in the control subjects, it was slightly weaker. For CP subjects of all ages, the most affected TA muscle common drive was markedly reduced compared with that of their least affected muscle as well as that of controls. These differences between the least and most affected TA muscles were unrelated to differences in the magnitude of EMG in the two muscles but positively correlated with ankle dorsiflexion velocity and joint angle during gait. Time- and frequency-domain analysis of ongoing EMG recruited during behaviorally relevant lower limb tasks provides a noninvasive and important measure of the central drive to motoneurons in subjects with CP.
Preservation of VGLUT1 synapses on ventral calbindin-immunoreactive interneurons and normal locomotor function in a mouse model of spinal muscular atrophy
Authors: Thirumalai Vatsala , Behrend Rachel M. , Birineni Swetha , Liu Wenfang , Blivis Dvir , O'Donovan Michael J.
Published: November 2012

Dysfunction in sensorimotor synapses is one of the earliest pathological changes observed in a mouse model [spinal muscular atrophy (SMA)Δ7] of spinal muscular atrophy. Here, we examined the density of proprioceptive and cholinergic synapses on calbindin-immunoreactive interneurons ventral to the lateral motor column. This population includes inhibitory Renshaw interneurons that are known to receive synaptic input from muscle spindle afferents and from motoneurons. At postnatal day (P)13, near the end stage of the disease, the somatic area of calbindin+ neurons in the L1/L2 and L5/L6 segments was reduced in SMAΔ7 mice compared with controls. In addition, the number and density of terminals expressing the glutamate vesicular transporter (VGLUT1) and the vesicular acetylcholine transporter (VAChT) were increased on calbindin+ cells in the L1-L2 but not in the L5-L6 segments of SMAΔ7 mice. In addition, the isolated spinal cord of SMA mice was able to generate locomotor-like activity at P4-P6 in the presence of a drug cocktail or in response to dorsal root stimulation. These results argue against a generalized loss of proprioceptive input to spinal circuits in SMA and suggest that the loss of proprioceptive synapses on motoneurons may be secondary to motoneuron pathology. The increased number of VGLUT1+ and VAChT+ synapses on calbindin+ neurons in the L1/L2 segments may be the result of homeostatic mechanisms. Finally, we have shown that abnormal locomotor network function is unlikely to account for the motor deficits observed in SMA mice at P4–6.
A neuromechanical model for the neuronal basis of curve walking in the stick insect
Authors: Knops S. , Tóth T. I. , Guschlbauer C. , Gruhn M. , Daun-Gruhn S.
Published: November 2012

The coordination of the movement of single and multiple limbs is essential for the generation of locomotion. Movement about single joints and the resulting stepping patterns are usually generated by the activity of antagonistic muscle pairs. In the stick insect, the three major muscle pairs of a leg are the protractor and retractor coxae, the levator and depressor trochanteris, and the flexor and extensor tibiae. The protractor and retractor move the coxa, and thereby the leg, forward and backward. The levator and depressor move the femur up and down. The flexor flexes, and the extensor extends the tibia about the femur-tibia joint. The underlying neuronal mechanisms for a forward stepping middle leg have been thoroughly investigated in experimental and theoretical studies. However, the details of the neuronal and mechanical mechanisms driving a stepping single leg in situations other than forward walking remain largely unknown. Here, we present a neuromechanical model of the coupled three joint control system of the stick insect's middle leg. The model can generate forward, backward, or sideward stepping. Switching between them is achieved by changing only a few central signals controlling the neuromechanical model. In kinematic simulations, we are able to generate curve walking with two different mechanisms. In the first, the inner middle leg is switched from forward to sideward and in the second to backward stepping. Both are observed in the behaving animal, and in the model and animal alike, backward stepping of the inner middle leg produces tighter turns than sideward stepping.
Motor learning and its sensory effects: time course of perceptual change and its presence with gradual introduction of load
Authors: Mattar Andrew A. G. , Darainy Mohammad , Ostry David J.
Published: November 2012

A complex interplay has been demonstrated between motor and sensory systems. We showed recently that motor learning leads to changes in the sensed position of the limb (Ostry DJ, Darainy M, Mattar AA, Wong J, Gribble PL. J Neurosci 30: 5384–5393, 2010). Here, we document further the links between motor learning and changes in somatosensory perception. To study motor learning, we used a force field paradigm in which subjects learn to compensate for forces applied to the hand by a robotic device. We used a task in which subjects judge lateral displacements of the hand to study somatosensory perception. In a first experiment, we divided the motor learning task into incremental phases and tracked sensory perception throughout. We found that changes in perception occurred at a slower rate than changes in motor performance. A second experiment tested whether awareness of the motor learning process is necessary for perceptual change. In this experiment, subjects were exposed to a force field that grew gradually in strength. We found that the shift in sensory perception occurred even when awareness of motor learning was reduced. These experiments argue for a link between motor learning and changes in somatosensory perception, and they are consistent with the idea that motor learning drives sensory change.
Effect of NaF, SnF2, and TiF4Toothpastes on Bovine Enamel and Dentin Erosion-Abrasion In Vitro
Authors: Comar Lívia Picchi , Gomes Marina Franciscon , Ito Naiana , Salomão Priscila Aranda , Grizzo Larissa Tercília , Magalhães Ana Carolina
Published: November 2012

The aim of this study was to compare the effect of toothpastes containing TiF4, NaF, and SnF2on tooth erosion-abrasion. Bovine enamel and dentin specimens were distributed into 10 groups (n=12): experimental placebo toothpaste (no F); NaF (1450 ppm F); TiF4(1450 ppm F); SnF2(1450 ppm F); SnF2(1100 ppm F) + NaF (350 ppm F); TiF4(1100 ppm F) + NaF (350 ppm F); commercial toothpaste Pro-Health (SnF2—1100 ppm F + NaF—350 ppm F, Oral B); commercial toothpaste Crest (NaF—1.500 ppm F, Procter & Gamble); abrasion without toothpaste and only erosion. The erosion was performed 4 × 90 s/day (Sprite Zero). The toothpastes’ slurries were applied and the specimens abraded using an electric toothbrush 2 × 15 s/day. Between the erosive and abrasive challenges, the specimens remained in artificial saliva. After 7 days, the tooth wear was evaluated using contact profilometry (μm). The experimental toothpastes with NaF, TiF4, SnF2, and Pro-Health showed a significant reduction in enamel wear (between 42% and 54%). Pro-Health also significantly reduced the dentin wear. The toothpastes with SnF2/NaF and TiF4/NaF showed the best results in the reduction of enamel wear (62–70%) as well as TiF4, SnF2, SnF2/NaF, and TiF4/NaF for dentin wear (64–79%) (P<0.05). Therefore, the experimental toothpastes containing both conventional and metal fluoride seem to be promising in reducing tooth wear.
The Functional-Analytic Properties of the Limitq-Bernstein Operator
Authors: Ostrovska Sofiya
Published: November 2012

The limitq-Bernstein operatorBq,0<q<1, emerges naturally as a modification of the Szász-Mirakyan operator related to the Euler distribution. The latter is used in theq-boson theory to describe the energy distribution in aq-analogue of the coherent state. Lately, the limitq-Bernstein operator has been widely under scrutiny, and it has been shown thatBqis a positive shape-preserving linear operator onC[0,1]with∥Bq∥=1. Its approximation properties, probabilistic interpretation, eigenstructure, and impact on the smoothness of a function have been examined. In this paper, the functional-analytic properties ofBqare studied. Our main result states that there exists an infinite-dimensional subspaceMofC[0,1]such that the restrictionBq|Mis an isomorphic embedding. Also we show that each such subspaceMcontains an isomorphic copy of the Banach spacec0.
Treatment of Non-Small-Cell Lung Cancer with Erlotinib following Gefitinib-Induced Hepatotoxicity: Review of 8 Clinical Cases
Authors: Yano Yukihiro , Namba Yoshinobu , Mori Masahide , Nakazawa Yukie , Nashi Ayumi , Kagami Shinichi , Niinaka Manabu , Yoneda Tsutomu , Kimura Hiromi , Yamaguchi Toshihiko , Yokota Soichiro
Published: November 2012

Objective. Gefitinib often induces liver damage. A few reports have described that the subsequent administration of erlotinib was associated with less hepatotoxicity, but the safety and efficacy of this treatment are still not fully investigated. Therefore, we evaluated retrospectively the patients with erlotinib following gefitinib-induced hepatotoxicity. Methods and Patients. We retrospectively reviewed the medical records between December 2007 and March 2010. The patients were evaluated including the following information: age, gender, histology of lung cancer, performance status, smoking status, epidermal growth factor receptor (EGFR) mutation status, liver metastasis, viral hepatitis, alcoholic liver injury, clinical response, and hepatotoxicity due to EGFR tyrosine kinase inhibitors. Results. We identified 8 patients with erlotinib following gefitinib-induced hepatotoxicity. All achieved disease control by gefitinib. Hepatotoxicity was grades 2 and 3 in 3 and 5 patients, respectively. The median duration of treatment with gefitinib was 112.5 days and the median time to gefitinib-induced hepatotoxicity was 51.5 days. The median duration of treatment with erlotinib was 171.5 days. Grade 1 and 2 erlotinib-induced hepatotoxicity was observed in 2 and 1 patient, respectively. Conclusions. Erlotinib administration with careful monitoring is thought to be a good alternative strategy for patients who respond well to gefitinib treatment but experience hepatotoxicity.