bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-talk between Notch and Hedgehog regulates hepatic stellate cell fate in mice
Authors: Xie Guanhua , Karaca Gamze , Swiderska-Syn Marzena , Michelotti Gregory A. , Krüger Leandi , Chen Yuping , Premont Richard T. , Choi Steve S. , Diehl Anna Mae
Published: May 2013

Liver repair involves phenotypic changes in hepatic stellate cells (HSCs) and reactivation of morphogenic signaling pathways that modulate epithelial-to-mesenchymal/mesenchymal-to-epithelial transitions, such as Notch and Hedgehog (Hh). Hh stimulates HSCs to become myofibroblasts (MFs). Recent lineage tracing studies in adult mice with injured livers showed that some MFs became multipotent progenitors to regenerate hepatocytes, cholangiocytes, and HSCs. We studied primary HSC cultures and two different animal models of fibrosis to evaluate the hypothesis that activating the Notch pathway in HSCs stimulates them to become (and remain) MFs through a mechanism that involves an epithelial-to-mesenchymal–like transition and requires cross-talk with the canonical Hh pathway. We found that when cultured HSCs transitioned into MFs, they activated Hh signaling, underwent an epithelial-to-mesenchymal–like transition, and increased Notch signaling. Blocking Notch signaling in MFs/HSCs suppressed Hh activity and caused a mesenchymal-to-epithelial–like transition. Inhibiting the Hh pathway suppressed Notch signaling and also induced a mesenchymal-to-epithelial–like transition. Manipulating Hh and Notch signaling in a mouse multipotent progenitor cell line evoked similar responses. In mice, liver injury increased Notch activity in MFs and Hh-responsive MF progeny (i.e., HSCs and ductular cells). Conditionally disrupting Hh signaling in MFs of bile-duct–ligated mice inhibited Notch signaling and blocked accumulation of both MF and ductular cells.

Conclusions:

The Notch and Hedgehog pathways interact to control the fate of key cell types involved in adult liver repair by modulating epithelial-to-mesenchymal–like/mesenchymal-to-epithelial–like transitions. (Hepatology 2013;58:1801–1813)
Stable oxygen and hydrogen isotopes as indicators of lake water recharge and evaporation in the lakes of the Yinchuan Plain
Authors: Qian Hui , Wu Jianhua , Zhou Yahong , Li Peiyue
Published: May 2013

The Yinchuan Plain has more than 2000 years of history of irrigation by diverting water from the Yellow River. Currently, the amount of water diverted from the Yellow River is about 21.7 times the water formed on the plain as a result of precipitation and inflow of groundwater. Under the intensive influence of irrigation, the plain changed from a desert into a rich and populous area, earning its name as ‘South China Beyond the Great Wall’, with lakes scattered across the Yinchuan Plain just as stars in the sky. In this research, 17 representative lakes were sampled to analyze and study 2H and 18O content; the results showed that lakes on the plain have undergone obvious non‐equilibrium evaporation. Recharges of the lakes can be divided into three types: recharge from the Yellow River, from groundwater and from both of these. The Craig–Gordon non‐equilibrium evaporation model for isotope fractionation was used to estimate the evaporation proportion of each lake. The results showed that evaporation from lakes on Yinchuan Plain is generally extensive under the dry climatic conditions. Most lakes have an evaporation proportion of over 25%, with the largest originating from Shahu lake and Gaomiaohu lake in the northern part of the plain, at 42.5% and 42.8%, respectively. The evaporation proportions calculated on the basis of 18O and 2H are very close to each other. This shows that the method used in this paper is feasible for estimating the evaporation proportions of lakes in areas with a heavy anthropogenic influence. Copyright © 2013 John Wiley & Sons, Ltd.
Internal‐to‐Cartesian back transformation of molecular geometry steps using high‐order geometric derivatives
Authors: Rybkin Vladimir V. , Ekström Ulf , Helgaker Trygve
Published: May 2013

In geometry optimizations and molecular dynamics calculations, it is often necessary to transform a geometry step that has been determined in internal coordinates to Cartesian coordinates. A new method for performing such transformations, the high‐order path‐expansion (HOPE) method, is here presented. The new method treats the nonlinear relation between internal and Cartesian coordinates by means of automatic differentiation. The method is reliable, applicable to any system of internal coordinates, and computationally more efficient than the traditional method of iterative back transformations. As a bonus, the HOPE method determines not just the Cartesian step vector but also a continuous step path expressed in the form of a polynomial, which is useful for determining reaction coordinates, for integrating trajectories, and for visualization. © 2013 Wiley Periodicals, Inc.
Cloud‐resolving simulation of TOGA‐COARE using parameterized large‐scale dynamics
Authors: Wang Shuguang , Sobel Adam H. , Kuang Zhiming
Published: May 2013

Variations in deep convective activity during the 4 month Tropical Ocean Global Atmosphere‐Coupled Ocean Atmosphere Response Experiment (TOGA‐COARE) field campaign are simulated using a cloud‐resolving model (CRM). Convection in the model is coupled to large‐scale vertical velocities that are parameterized using one of two different methods: the damped gravity wave (Damped‐wave) method and the weak temperature gradient (WTG) method. The reference temperature profiles against which temperature anomalies are computed are taken either from observations or from a model integration with no large‐scale vertical motion (but other forcings taken from observations); the parameterized large‐scale vertical velocities are coupled to those temperature (or virtual temperature) anomalies. Sea surface temperature, radiative fluxes, and relaxation of the horizontal mean horizontal wind field are also imposed. Simulations with large‐scale vertical velocity imposed from the observations are performed for reference. The primary finding is that the CRM with parameterized large‐scale vertical motion can capture the intraseasonal variations in rainfall to some degree. Experiments in which one of several observation‐derived forcings is set to its time‐mean value suggest that those which influence direct forcings on the moist static energy budget—surface wind speed and sea surface temperature (which together influence surface evaporation) and radiative cooling—play the most important roles in controlling convection, particularly when the Damped‐wave method is used. The parameterized large‐scale vertical velocity has a vertical profile that is too bottom‐heavy compared to observations when the Damped‐wave method is used with vertically uniform Rayleigh damping on horizontal wind, but is too top‐heavy when the WTG method is used.
Reliability Analysis for Degradation of Locomotive Wheels using Parametric Bayesian Approach
Authors: Lin Jing , Asplund Matthias , Parida Aditya
Published: May 2013

This paper undertakes a reliability study using a Bayesian survival analysis framework to explore the impact of a locomotive wheel's installed position on its service lifetime and to predict its reliability characteristics. The Bayesian Exponential Regression Model, Bayesian Weibull Regression Model and Bayesian Log‐normal Regression Model are used to analyze the lifetime of locomotive wheels using degradation data and taking into account the position of the wheel. This position is described by three different discrete covariates: the bogie, the axle and the side of the locomotive where the wheel is mounted. The goal is to determine reliability, failure distribution and optimal maintenance strategies for the wheel. The results show that: (i) under specified assumptions and a given topography, the position of the locomotive wheel could influence its reliability and lifetime; (ii) the Bayesian Log‐normal Regression Model is a useful tool. Copyright © 2013 John Wiley & Sons, Ltd.
Trapping and hysteresis in two‐phase flow in porous media: A pore‐network study
Authors: Joekar‐Niasar V. , Doster F. , Armstrong R. T. , Wildenschild D. , Celia M. A.
Published: May 2013

Several models for two‐phase flow in porous media identify trapping and connectivity of fluids as an important contribution to macroscale hysteresis. This is especially true for hysteresis in relative permeabilities. The trapping models propose trajectories from the initial saturation to the end saturation in various ways and are often based on experiments or pore‐network model results for the endpoints. However, experimental data or pore‐scale model results are often not available for the trajectories, that is, the fate of the connectivity of the fluids while saturation changes. Here, using a quasi static pore‐network model, supported by a set of pore‐scale laboratory experiments, we study how the topology of the fluids changes during drainage and imbibition including first, main and scanning curves. We find a strong hysteretic behavior in the relationship between disconnected nonwetting fluid saturation and the wetting fluid saturation in a water‐wet medium. The coalescence of the invading nonwetting phase with the existing disconnected nonwetting phase depends critically on the presence (or lack thereof) of connected nonwetting phase at the beginning of the drainage process as well as on the pore geometry. This dependence involves a mechanism we refer to as “reversible corner filling.” This mechanism can also be seen in laboratory experiments in volcanic tuff. The impact of these pore‐network model results on existing macroscopic models is discussed.
Nitrogen determination by SEM‐EDS and elemental analysis
Authors: Gazulla M.F. , Rodrigo M. , Blasco E. , Orduña M.
Published: May 2013

This paper describes a methodology for the analysis of nitrogen by scanning electron microscope with an energy dispersive X‐ray spectrometer (SEM‐EDS). The methodology was developed to have a rapid and accurate alternative method to the elemental analysis by combustion and thermoconductivity detection that does not imply the decomposition of the sample.

Two methods by SEM‐EDS were established: a quantitative method trying to construct a calibration curve with reference materials and another using the standardless method provided with the instrument software, and the results were compared with those obtained by elemental analysis using two instruments that work at different temperature. An important matrix effect was found when trying to construct a calibration curve for SEM‐EDS for any kind of material, being corrected when using the standardless method because this method corrects the matrix effect.

The quantification of nitrogen by SEM‐EDS is a good alternative to elemental analysis by combustion and thermoconductivity detection in those cases where the sample has a very high decomposition temperature. Copyright © 2013 John Wiley & Sons, Ltd.
Theoretical and experimental study on the angular dependence of scattering processes in X‐ray fluorescence systems
Authors: Guerra M. , Manso M. , Pessanha S. , Longelin S. , Carvalho M. L.
Published: May 2013

The role of X‐ray reflectivity, coherent, and incoherent scattering has been studied in light samples. The angular dependence of these processes was evaluated, and the best geometrical settings for X‐ray fluorescence spectrometers was studied both for symmetrical and asymmetrical setups. Emphasis is given to biaxial planar geometry rather than triaxial orthogonal geometry, due to the use of low power X‐ray tubes and non‐cryogenic detectors in portable instruments rather than desktop or larger laboratory instruments. The detection limits of the reference material Orchard leaves (NBS‐1571) were calculated for each studied geometry. The specular reflectivity at the sample plane, as well as the irradiated volume was found to be of paramount importance in the angular dependence of the coherent and incoherent peaks description. The best geometry for symmetrical spectrometers in the 1–30 keV energy range is in the 70°–90° interval due to the Compton and Rayleigh scatterings of the incident radiation. Copyright © 2013 John Wiley & Sons, Ltd.
Social studies marginalization: Examining the effects on K-6 pre-service teachers and students
Authors: Hubbard Janie
Published: May 2013

The consequences of a trend to marginalize social studies in the early grades are complex and widespread, as a new wave of novice teachers and K-6 students are receiving a message clearly implying that social studies education is unimportant. Convincing them of the value in teaching and learning social studies is progressively becoming more difficult for social studies methods instructors. The purpose of this study was to examine pre-service teachers’ observations of the extent to which social studies is being marginalized, possible barriers involved, and the impact that this phenomenon has on pre-service teachers and K-6 students in the classroom. Through a mixed-method design, 88 pre-service teachers were asked to report their classroom observations. Over half observed social studies instruction. Of those who observed social studies instruction, about a third indicated that teachers taught 5–15 min per day. Pre-service teachers reported personal success in planning and teaching social studies lessons during their practicum experiences; likewise, K-6 students were motivated by pre-service teachers’ student-centered activities in the lessons. The results of this study provide one form of current documentation regarding the effects of social studies marginalization in K-6 schools.
Nonlinear Electrohydrodynamic Stability of Two Superposed Walters B′ Viscoelastic Fluids in Relative Motion Through Porous Medium
Authors: El-Sayed M. F. , Eldabe N. T. , Haroun M. H. , Mostafa D. M.
Published: May 2013

A nonlinear stability of two superposed semi-infinite Walters B′ viscoelastic dielectric fluids streaming through porous media in the presence of vertical electric fields in absence of surface charges at their interface is investigated in three dimensions. The method of multiple scales is used to obtain a Ginzburg-Landau equation with complex coefficients describing the behavior of the system. The stability of the system is discussed both analytically and numerically in linear and nonlinear cases, and the corresponding stability conditions are obtained. It is found, in the linear case, that the surface tension and medium permeability have stabilizing effects, and the fluid velocities, electric fields and kinematic viscoelastici-ties have destabilizing effects, while the porosity of porous medium and kinematic viscosities have dual role on the stability. In the nonlinear case, it is found that the fluid velocities, kinematic viscosities, kinematic viscoelasticities, surface tension and porosity of porous medium have stabilizing effects; while the electric fields and medium permeability have destabilizing effects.
Effect of polyphenol-rich grape seed extract on ambulatory blood pressure in subjects with pre- and stage I hypertension
Authors: Ras Rouyanne T. , Zock Peter L. , Zebregs Yvonne E. M. P. , Johnston Neil R. , Webb David J. , Draijer Richard
Published: May 2013

Dietary polyphenols, such as those from grape products, may exert beneficial effects on cardiovascular health, including anti-hypertensive effects. We investigated the effect of a specific grape seed extract (GSE) rich in low-molecular-weight polyphenolic compounds on ambulatory blood pressure (ABP) in untreated subjects with pre- and stage I hypertension. In addition, potential mechanisms that could underlie the hypothesised effect of GSE on blood pressure (BP), and platelet aggregation, were explored. The study was designed as a double-blind, placebo-controlled, randomised, parallel-group intervention study including seventy healthy subjects with systolic BP between 120 and 159 mmHg. A 1-week run-in period was followed by an 8-week intervention period, during which subjects consumed capsules containing either 300 mg/d of GSE or a placebo (microcrystalline cellulose). Before and after the intervention, daytime ABP readings, 24 h urine samples and fasting and non-fasting blood samples were taken. The mean baseline systolic BP was 135·8 (se 1·3) mmHg and diastolic BP was 81·5 (se 0·9) mmHg. BP values were modestly, but not significantly, affected by the polyphenol-rich GSE treatment v. placebo with an effect of − 3·0 mmHg for systolic BP (95 % CI − 6·5, 0·5) and − 1·4 mmHg for diastolic BP (95 % CI − 3·5, 0·6). Vasoactive markers including endothelin-1, NO metabolites and asymmetric dimethylarginine, plasma renin activity and platelet aggregation were not affected by the GSE intervention. Our findings show that consumption of polyphenol-rich GSE does not significantly lower ABP in untreated subjects with pre- and stage I hypertension.
The Institutional Politics of Territorial Redistribution: Federalism and Equalization Policy in Australia and Canada
Authors: Lecours André , Béland Daniel
Published: May 2013

Abstract.A key challenge for comparative politics is to explain the varying degrees of political conflict triggered by the territorial redistribution of financial resources. Federal systems pose this question particularly acutely since they typically operate equalization programs that generate different levels and patterns of intergovernmental conflict. For instance, in Canada equalization has generated serious conflict between federal and provincial governments whereas in Australia it has only led to low-level grumblings on the part of some states which have taken shots at others. This article sheds light on the causes for conflict around the territorial redistribution of financial resources by explaining why equalization has produced more severe intergovernmental conflict in Canada than in Australia. It argues that institutional factors linked to the governance structures of equalization and the nature of federalism are at the heart of the cross-national difference. More specifically, the presence of an arms-length agency administrating equalization in Australia compared to executive discretion over the program in Canada and the weaker status and lesser power of states in comparison to Canadian provinces means that equalization policy is more subject to political challenges in Australia than in Canada.

Résumé.Une question majeure pour la politique comparée contemporaine, et plus particulièrement le fédéralisme comparé, est celle des conflits politiques et intergouvernementaux générés par la distribution territoriale des ressources fiscales. Au Canada, au cours de la dernière décennie, le programme de péréquation a suscité des conflits importants entre le gouvernement fédéral et les provinces, tandis qu'en Australie la péréquation ne provoque qu'un mécontentement épisodique entre les états fédérés. Cet article cherche à expliquer cette différence. Il suggère que des facteurs institutionnels liés à la gouvernance de la péréquation et à la nature des systèmes fédéraux sont au centre de l'explication. Plus précisément, l'article suggère que la présence d'une agence quasi-indépendante pour administrer la péréquation en Australie et son absence au Canada ainsi que la faiblesse relative des états australiens par rapport aux provinces canadiennes font que la péréquation au Canada est plus sujette aux attaques politiques qu'en Australie.
Shedding Light on Canada's Foreign Policy Alignment
Authors: Paquin Jonathan , Beauregard Philippe
Published: May 2013

Abstract.The purpose of this article is to explore the issue of alignment in Canadian foreign policy. The main research question is whether Canada's responses to foreign crises aligned with those of its allies, and if so, which allies and why. The study proceeds in two steps. First, it tests four major theoretical perspectives that could explain Canada's behaviour: continentalism, transatlantism, the Anglosphere argument and unilateralism. By performing a computer-generated content analysis, the article assesses these propositions by focusing on and comparing Canada's official declarations to those of the United States, France and Britain to six foreign crises that occurred between 2004 and 2011. Second, the analysis identifies whether there is a difference between the Harper and Martin governments' responses to foreign crises. The research provides quantitative and qualitative evidence suggesting that Canada's foreign policy alignment primarily tends toward a transatlantic orientation. It also shows that the Harper government was less in line with Washington than was the previous Liberal government of Paul Martin, which challenges the conventional wisdom of Canadian foreign policy.

Résumé.Cet article explore l'enjeu de l'alignement en politique étrangère canadienne et pose la question de recherche suivante : est-ce qu'à l'égard des crises étrangère le Canada s'aligne sur les positions de ses alliés et, si oui, lesquels et pourquoi? Tout d'abord, l'article présente quatre perspectives théoriques susceptibles d'expliquer le comportement du Canada : le continentalisme, le transatlantisme, la thèse de l'anglosphère et celle de l'unilatéralisme. En ayant recours à une analyse de contenu assistée par ordinateur, cet article teste la validité de ces propositions en comparant les déclarations officielles du Canada à celles des États-Unis, de la France et de l'Angleterre à l'égard de six crises survenues entre 2004 et 2011. Ensuite, l'analyse cherche à identifier s'il y a une différence entre les réponses des gouvernements Harper et Martin à l'égard de ces crises. L'étude fournit des données empiriques de type qualitatif et quantitatif qui suggèrent que le Canada a eu une orientation transatlantique lors de la gestion de ces crises internationales. Elle montre également que le gouvernement Harper est moins aligné sur les positions de Washington que ne le fut le précédent gouvernement libéral, ce qui ébranle certaines idées communément admises en politique étrangère canadienne.
Evaluation of process and input–output-based life-cycle assessment of Irish milk production
Authors: YAN M.-J. , HUMPHREYS J. , HOLDEN N. M.
Published: May 2013

Agricultural specialists, particularly animal scientists, tend to use process-based life-cycle assessments (LCA), which describe the production system as a series of processes, to study the environmental impact of milk production based on their experimental data. Another approach called input–output (I–O) based LCA, which uses the economic transaction tables and national environmental accounts to determine the environmental impact triggered by final demand of milk production, is often less used due to data scarcity and higher uncertainty. In the current paper, process-based and I–O-based LCA models were developed to evaluate the greenhouse gas (GHG) and acidifying emissions from pasture-based milk production in Ireland. Process-based LCA found 1338·3 kg CO2 eq and 14·4 kg SO2 eq/t energy-corrected milk (ECM), and revealed details related to the farm management. The I–O based LCA found 1003·1 kg CO2 eq and 12·7 kg SO2 eq/tonne ECM and suggested that the agriculture, forestry and fishery (AFF) sector itself was largely responsible for the environmental impact of AFF products, rather than economic interaction with other sectors. The process-based LCA was found to be suitable for developing farm-scale sustainability strategies if variation of tactics across farms is provided, while the I–O based LCA offered potential sustainability guidance at the national scale. Further work is required to incorporate foreign production into the I–O table to account fully for imported goods and services. A detailed disaggregation within the AFF sector is also needed to gain a better understanding of the environmental sustainability of agricultural commodities. The present paper thus provides interesting results for the dairy industry, dairy researchers and LCA practitioners on further understanding of the environmental impact of milk production.
Sequential Sales as a Test of Adverse Selection in the Market for Slaves
Authors: Pritchett Jonathan , Smith Mallorie
Published: May 2013

When imported slaves were first sold in New Orleans, buyers were unaware of the slaves’ unobservable characteristics. In time, the new owners learned more about their slaves and may have resold the “lemons.” Previous research suggests that buyers anticipated such adverse selection and reduced their bids for these slaves. Consequently, we should observe lower prices for resold slaves. We test this proposition by linking the sequential sales records of 568 slaves. Through a comparison of initial and resale prices, we find little evidence to support the hypothesis that adverse selection lowered the price of resold slaves.
Use of stable isotope ratios to characterize potential shifts in the isotopic niches of grazing insects following an amphibian decline in a Neotropical stream
Authors: Barnum Thomas R. , Verburg Piet , Kilham Susan S. , Whiles Matt R. , Lips Karen R. , Colón-Gaud Checo , Pringle Catherine M.
Published: May 2013

Neotropical streams are losing dominant consumer groups as a result of disease-driven amphibian declines. The herbivorous tadpoles of Lithobates warszewitschii were once abundant in the Rio Maria in the Eastern Cordillera Central of Panama, where they consumed algae and organic matter. The decline of this once abundant grazer has the potential to affect the resources consumed by insect grazers in this system. Stable isotopes were used to characterize changes in the resource use before and after amphibian declines of four abundant insect grazer taxa: Stenonema spp., Thraulodes spp., Psephenus spp. and Petrophila spp. We collected 11 isotope samples of L. warszewitschii and 27 isotope samples of these insect taxa in 2006, and then 24 more isotope samples of the same insect taxa in 2008, 20 mo. after a disease-driven amphibian extirpation. We also tested for potential functional redundancy of insects with tadpoles by comparing the post-decline isotopic niche of each insect taxon to the isotopic niche of L. warszewitschii. The isotopic niche of Psephenus spp., Petrophila spp. and Stenonema spp. shifted from 2006 to 2008, but none of the insect taxa in 2008 occupied the same isotopic niche as tadpoles. Our study builds on previous evidence that the ecological roles of tadpoles were not replaced through functional redundancy after amphibian declines.
Cognitive Reserve and Brain Reserve in Prodromal Huntington's Disease
Authors: Bonner-Jackson Aaron , Long Jeffrey D. , Westervelt Holly , Tremont Geoffrey , Aylward Elizabeth , Paulsen Jane S. ,   The PREDICT-HD Investigators and Coordinators of the Huntington Study Group
Published: May 2013

Huntington disease (HD) is associated with decline in cognition and progressive morphological changes in brain structures. Cognitive reserve may represent a mechanism by which disease-related decline may be delayed or slowed. The current study examined the relationship between cognitive reserve and longitudinal change in cognitive functioning and brain volumes among prodromal (gene expansion-positive) HD individuals. Participants were genetically confirmed individuals with prodromal HD enrolled in the PREDICT-HD study. Cognitive reserve was computed as the composite of performance on a lexical task estimating premorbid intellectual level, occupational status, and years of education. Linear mixed effects regression (LMER) was used to examine longitudinal changes on four cognitive measures and three brain volumes over approximately 6 years. Higher cognitive reserve was significantly associated with a slower rate of change on one cognitive measure (Trail Making Test, Part B) and slower rate of volume loss in two brain structures (caudate, putamen) for those estimated to be closest to motor disease onset. This relationship was not observed among those estimated to be further from motor disease onset. Our findings demonstrate a relationship between cognitive reserve and both a measure of executive functioning and integrity of certain brain structures in prodromal HD individuals. (JINS, 2013, 19, 1–12).
Energy adjustment of nutrient intakes is preferable to adjustment using body weight and physical activity in epidemiological analyses
Authors: Rhee Jinnie J , Cho Eunyoung , Willett Walter C
Published: May 2013

Objective

Adjustment for body weight and physical activity has been suggested as an alternative to adjusting for reported energy intake in nutritional epidemiology. We examined which of these approaches would yield stronger correlations between nutrients and their biomarkers.

Design

A cross-sectional study in which dietary fatty acids, carotenoids and retinol were adjusted for reported energy intake and, separately, for weight and physical activity using the residual method. Correlations between adjusted nutrients and their biomarkers were examined.

Setting

USA.

Subjects

Cases and controls from a nested case–control study of erythrocyte fatty acids and CHD (n442) and of plasma carotenoids and retinol and breast cancer (n1254).

Results

Correlations between intakes and plasma levels oftrans-fatty acids were 0·30 (energy-adjusted) and 0·16 (weight- and activity-adjusted); for erythrocyte levels, the corresponding correlations were 0·37 and 0·25. Energy-adjusted intakes of linoleic acid and α-linolenic acid were more strongly correlated with their respective biomarkers than weight- and activity-adjusted intakes, but the differences were not significant except for linoleic acid (erythrocyte). Weight- and activity-adjusted DHA intake was slightly more strongly correlated with its plasma biomarker than energy-adjusted intake (0·37v.0·34). Neither method made a difference for DHA (erythrocyte), carotenoids and retinol.

Conclusions

The effect of energy adjustment depends on the nutrient under investigation, and adjustment for energy calculated from the same questionnaire used to estimate nutrient intakes improves the correlation of some nutrients with their biomarkers appreciably. For the nutrients examined, adjustment using weight and physical activity had at most a small effect on these correlations.
Universal Variable Brightfield–Darkfield Contrast: A Variant Technique for Improved Imaging of Problematic Specimens in Light Microscopy
Authors: Piper Timm , Piper Jörg
Published: May 2013

Several problematic specimens, especially when composed of a complex three-dimensional architecture or very high or ultralow ranges in regional thickness and density, can be observed in improved clarity and precision when universal variable brightfield–darkfield contrast (UVBDC) is used. In this method, two different partial images are optically superimposed and interfere with each other, contributing to complementary visual information: a brightfield and a darkfield image. These images can be generated with concentric-peripheral, paraxial, or axial illuminating light. In all variants, variable transitions between bright- and darkfield are achievable. By use of a pancratic condenser (zoom system), the illuminating light can be universally adjusted and optimally adapted to each type of specimen and each type of objective (glass and mirror lenses). The concentric-peripheral variant is preferably carried out with normal glass lenses, the axial variant with mirror lenses. Glass lenses can also be used for UVBDC based on axial or paraxial light when combined with a special contrast tube, which is described in detail. Which technical variant of UVBDC might lead to the best result may be determined by the particular properties of the specimen, but all techniques described promise significant improvements in image quality and visual information.
An investigation of rotational issues for rectal carcinoma treated with radiotherapy
Authors: Taylor Dominique A. , ffrench Thomas , Sale Charlotte A. , Foulstone Paul
Published: May 2013

Purpose

To quantify the amount of inter-fractional pitch for rectal carcinoma patients, to investigate the dosimetric impact of pitch on the target volume and critical structures and to determine a tolerance where no pitch correction is required.

Materials and methods

Daily pre-treatment images of rectal carcinoma patients were analysed to determine the residual pitch compared with the computed tomography (CT) planning scan. The dosimetric impact of pelvic rotation was modelled. The dose coverage of the clinical target volume (CTV) and small bowel were evaluated using dose–volume histograms.

Results

Pre-treatment images had a mean of 0·27° and standard deviation was 2·23°. The volume of CTV receiving 95% of the prescription dose altered by 0·1% when up to ±10° of pitch was simulated.

Conclusions

No clinically significant change in CTV coverage was found (when ±10° of pitch was simulated). A tolerance of ±10° of pitch has been implemented for rectal carcinoma patients treated with three-dimensional conformal radiotherapy in our institution, when daily pre-treatment imaging with a zero action threshold for translational shifts is used.
Diversity and bioprospecting of fungal communities associated with endemic and cold-adapted macroalgae in Antarctica
Authors: Godinho Valéria M , Furbino Laura E , Santiago Iara F , Pellizzari Franciane M , Yokoya Nair S , Pupo Diclá , Alves Tânia M A , S Junior Policarpo A , Romanha Alvaro J , Zani Carlos L , Cantrell Charles L , Rosa Carlos A , Rosa Luiz H
Published: May 2013

We surveyed the distribution and diversity of fungi associated with eight macroalgae from Antarctica and their capability to produce bioactive compounds. The collections yielded 148 fungal isolates, which were identified using molecular methods as belonging to 21 genera and 50 taxa. The most frequent taxa were Geomyces species (sp.), Penicillium sp. and Metschnikowia australis. Seven fungal isolates associated with the endemic Antarctic macroalgae Monostroma hariotii (Chlorophyte) displayed high internal transcribed spacer sequences similarities with the psychrophilic pathogenic fungus Geomyces destructans. Thirty-three fungal singletons (66%) were identified, representing rare components of the fungal communities. The fungal communities displayed high diversity, richness and dominance indices; however, rarefaction curves indicated that not all of the fungal diversity present was recovered. Penicillium sp. UFMGCB 6034 and Penicillium sp. UFMGCB 6120, recovered from the endemic species Palmaria decipiens (Rhodophyte) and M. hariotii, respectively, yielded extracts with high and selective antifungal and/or trypanocidal activities, in which a preliminary spectral analysis using proton nuclear magnetic resonance spectroscopy indicated the presence of highly functionalised aromatic compounds. These results suggest that the endemic and cold-adapted macroalgae of Antarctica shelter a rich, diversity and complex fungal communities consisting of a few dominant indigenous or mesophilic cold-adapted species, and a large number of rare and/or endemic taxa, which may provide an interesting model of algal–fungal interactions under extreme conditions as well as a potential source of bioactive compounds.
Epigenetic reprogramming: preparing the epigenome for the next generation
Authors: Rose Catherine M. , van den Driesche Sander , Meehan Richard R. , Drake Amanda J.
Published: May 2013

Epigenetic reprogramming of germ cells involves the genome-wide erasure and subsequent re-establishment of DNA methylation, along with reprogramming of histone modification profiles and the eventual incorporation of histone variants. These linked processes appear to be key for the establishment of the correct epigenetic regulation of this cell lineage. Mouse studies indicate that DNA demethylation may be initiated at E (embryonic day) 8 with rapid and substantial erasure occurring between E11.5 and E12.5. This is accompanied by a reduction in H3K9 dimethylation and an increase in H3K27 trimethylation. DNA remethylation subsequently occurs in late gestation in male germ cells and postnatally in female germ cells. This reprogramming occurs throughout the genome, with the exception of specific sequences. The conservation of this process across species remains largely undetermined, and, with recent discoveries of new DNA modifications, there is still much to be explored.
Do age-related changes in DNA methylation play a role in the development of age-related diseases?
Authors: van Otterdijk Sanne D. , Mathers John C. , Strathdee Gordon
Published: May 2013

DNA methylation is an important epigenetic mechanism in mammalian cells. It occurs almost exclusively at CpG sites and has a key role in a number of biological processes. It plays an important part in regulating chromatin structure and has been best studied for its role in controlling gene expression. In particular, hypermethylation of gene promoters which have high levels of CpG sites, known as CpG islands, leads to gene inactivation. In healthy cells, however, it appears that only a small number of genes are controlled through promoter hypermethylation, such as genes on the inactivated X-chromosome or at imprinted loci, and most promoter-associated CpG islands remain methylation-free regardless of gene expression status. However, a large body of evidence has now shown that this protection from methylation not only breaks down in a number of pathological conditions (e.g. cancer), but also already occurs during the normal process of aging. The present review focuses on the methylation changes that occur during healthy aging and during disease development, and the potential links between them. We focus especially on the extent to which the acquisition of aberrant methylation changes during aging could underlie the development of a number of important age-related pathological conditions.
Flowing afterglow measurements of the density dependence of gas-phase ion-ion mutual neutralization reactions
Authors: Shuman Nicholas S. , Viggiano Albert A. , Johnsen Rainer
Published: May 2013

We have studied the dependence of several ion-ion mutual neutralization (MN) reactions on helium density in the range from 1.6 × 1016 to 1.5 × 1017 cm−3 at 300 K, using the Variable Electron and Neutral Density Attachment Mass Spectrometry method. The rate coefficients of the reactions Ar+ + Br2−, Ar+ + SF6−, and Ar+ + C7F14− were found to be independent of gas density over the range studied, in disagreement with earlier observations that similar MN reactions are strongly enhanced at the same gas densities. The cause of the previous enhancement with density is traced to the use of “orbital-motion-limit” theory to infer ion densities from the currents collected by ion-attracting Langmuir probes in a region where it is not applicable.
A model for thickness effect on the band gap of amorphous germanium film
Authors: Wang Xiao-Dong , Wang Hai-Feng , Chen Bo , Li Yun-Peng , Ma Yue-Ying
Published: May 2013

A Mott-Davis-Paracrystalline model was proposed to interpret thickness effect of the band gap for amorphous germanium (a-Ge). We believe that a-Ge has a semiconductor-alloy-like structure, it may contain medium-range order (MRO) and continuous random network (CRN) simultaneously and there is a dependence of MRO/CRN ratio on film thickness and preparation methods/parameters. For MRO is dominant, thickness effect can be described by one-dimensional quantum confinement (ODQC) effect of nanocrystals and strain-induced shrinkage of the band gap; For CRN is dominant, thickness dependence can be interpreted by changes in the quality of a CRN and ODQC effect of nanoamorphous phase.
Dynamics of acetone photooxidation on TiO2(110): State-resolved measurements of methyl photoproducts
Authors: Kershis Matthew D. , Wilson Daniel P. , White Michael G.
Published: May 2013

State-resolved laser techniques were used to study the internal state distributions of gas phase methyl radicals which are produced during the photooxidation of acetone on TiO2(110). This approach was used as a means of understanding the nature of the bimodal kinetic energy distributions for these radicals. Specifically, we investigated the population of the ν2 “umbrella mode” which has been shown to be important in similar photodissociation reactions where methyl radicals are liberated. We observed that for methyl radicals undergoing prompt dissociation (EK = 0.15 eV), the vibrational population in the umbrella mode is quite cold and can be characterized by a Tvib = 151 ± 15 K. Methyl radicals in this channel were also characterized by a rotational energy distribution of Trot = 325 ± 25 K which is comparable to the gas phase value obtained by acetone photolysis. State-resolved energy distributions also show that methyl radicals which are vibrationally excited have an overall kinetic energy distribution which is ∼35 meV less than those which are in their vibrational ground state. This value is comparable to, but not exactly in agreement with, the known vibrational spacing of the ν2 mode and suggests that vibrationally excited methyl radicals have less energy available for translation.
Theoretical insight into electronic spectra of carbon chain carbenes H2Cn(n= 3−10)
Authors: Zhang Yanxin , Wang Li , Li Yuanyuan , Zhang Jinglai
Published: May 2013

Ground-state geometries of carbenes H2Cn (n = 3−10) have been fully optimized with the C2ν-symmetry constraint at the density functional theory and restricted-spin coupled-cluster single-double plus perturbative triple excitation levels of theory, respectively. Comparison of structures corresponding to the X1A1 and B1B1 electronic states has been made by the complete active space self-consistent field calculations. Parity alternation effect on various properties of the ground-state geometries has been discovered in the present study, which generally gives illustration for the relative stabilities of the titled carbon chains. Further calculations on their electronic spectra have been carried out by means of the complete active space second-order perturbation theory method along with the cc-pVTZ basis set. It is found that the vertical excitation energies of the dipole-allowed B1B1 ← X1A1 transition in the gas phase are 2.28, 4.75, 1.69, 3.66, 1.30, 2.94, 1.12, and 2.49 eV, respectively, which agree very well with the available experimental result for H2C3 (2.27 eV). In addition, the vertical excitation energies for both transitions B1B1 ← X1A1 and A1A2 ← X1A1 are found to obey a nonlinear ΔE-n relationship as a function of chain size by performing curves fitting.
Dynamics simulation of the interaction between serine and water
Authors: Liu Yang , Zhang Peng , Lu Ying-Bo , Han Sheng-Hao , Yu Hui
Published: May 2013

Using the first principles density functional theory (DFT), we simulated the neutron scattering spectra of the hydration dynamics of serine. Experimental data analyses have shown that dissociative H2O molecules were more likely to form hydrogen bonds (H-bonds) with an –OH group in monohydrated serine and easily shift to a –${\rm NH}_3 ^ +$ NH 3+ group at a higher hydration level [P. Zhang, Y. Zhang, S. H. Han, Q. W. Yan, R. C. Ford, and J. C. Li, J. Phys. Chem. A 110, 5000 (2006)10.1021/jp0569741]. We set the 1:1 ratio hydrated compounds at the two positions and found that the H2O could be optimized to form H-bonds with –OH and –NH3+ separately. When the simulated phonon signals of the –OH…H2O and –NH3+…H2O combinations were summed on a 3:1 scale, the calculating spectra were in good agreement with the experimental results, especially for the peak at 423 cm−1 of the –OH…H2O combination and the peak at 367 cm−1 of the –NH3+…H2O combination, which mutually complemented the real spectrum. We confirm that H2O may break the intermolecular H-bonds of the interlaced binding –OH to form a new structure, and that with the skeleton deformation of serine, H2O forms stronger H-bonds more often with the –NH3+ side indicating the flexible dynamic mechanism of the serine hydration process.
Absorption induced modulation of magnetism in two-dimensional metal-phthalocyanine porous sheets
Authors: Zhou Jian , Sun Qiang
Published: May 2013

Metal-phthalocyanine porous sheets have uniformly dispersed metal sites in Pc framework, making absorption happen naturally. Here, we explore the effects of absorption of chlorine atoms on magnetism in transition metal embedded phthalocyanine (poly-TMPc) sheets with TM = Cr, Mn, and Fe. We show that when one Cl is absorbed on the TM, the strong square planar crystal field becomes weak in a square pyramidal configuration and the TM is in the +3 oxidized state, resulting in the magnetic moment of 3, 4, and 5 μB for Cr, Mn, and Fe, respectively, with weak antiferromagnetic couplings. When another Cl is introduced to the TM on the other side, it extracts one electron from the Pc framework making the substrate p-doped. The magnetic coupling is antiferromagnetic for poly-CrPc-2Cl and the poly-FePc-2Cl, while it becomes ferromagnetic for poly-MnPc-2Cl, suggesting that absorption can effectively modulate the bonding environment and tune the magnetic properties of the systems, and the controlled absorption can be used to tailor materials.
Co-existence of ferrimagnetism and spin-glass state in the spinel Co2SnO4
Authors: Thota Subhash , Seehra M. S.
Published: May 2013

The nature of magnetic ordering in the inverted spinel Co2SnO4 = [Co2+][Co2+Sn4+]O4 is investigated by measuring the temperature dependence of its magnetization (M) and ac-susceptibilities (χ′ and χ″) in different magnetic fields (H) using a superconducting quantum interference device magnetometer. The polycrystalline sample with a grain size of 3–5 μm was prepared by the solid-state route and characterized by x-ray diffraction and scanning electron microscopy. Above the ferrimagnetic Néel temperature TN = 41 K, χdc = M/H fits well with the Néel' expression for the two-sublattice model of ferrimagnetism. The ferrimagnetic ordering is suggested to result from different magnetic moments of Co2+ on the A sites (3.87 μB) and B sites (4.16 μB) and antiferromagnetic molecular field constants with magnitudes NAA = 13.6, NBB = 36.8, and NAB = 33.2. The temperature variations of χ′ and χ″ under various dc-bias fields suggest the existence of a spin-glass (SG) phase for T < TSG = 39.1 K in which only the transverse spin components are frozen below TSG. This co-existence of longitudinal ferrimagnetic order below TN = 41 K and transverse SG state below TSG = 39.1 K is suggested to result from the presence of non-magnetic Sn4+ ions on the B sites.
Effect of nanoparticle polarization on relative permittivity of transformer oil-based nanofluids
Authors: Miao Jin , Dong Ming , Ren Ming , Wu Xuezhou , Shen Liangping , Wang Hao
Published: May 2013

Our experiments on a transformer oil-based nanofluid (NF) with ZnO nanoparticles reveal a higher relative permittivity than that of pure transformer oil. Meanwhile, the relative permittivity of ZnO NF presents a linear increase with nanoparticle volumetric concentration and a linear decrease with ambient temperature. A model based on nanoparticle polarization is proposed to investigate the mechanisms of NF relative permittivity. Analysis of the presented polarization model suggests that the value of the NF relative permittivity is dominantly determined by transformer oil, while the higher relative permittivity of NFs compared with that of pure oil is mainly caused by nanoparticle inner polarization.
Pre-patterned ZnO nanoribbons on soft substrates for stretchable energy harvesting applications
Authors: Ma Teng , Wang Yong , Tang Rui , Yu Hongyu , Jiang Hanqing
Published: May 2013

Three pre-patterned ZnO nanoribbons in different configurations were studied in this paper, including (a) straight ZnO nanoribbons uniformly bonded on soft substrates that form sinusoidal buckles, (b) straight ZnO nanoribbons selectively bonded on soft substrates that form pop-up buckles, and (c) serpentine ZnO nanoribbons bonded on soft substrates via anchors. The nonlinear dynamics and random analysis were conducted to obtain the fundamental frequencies and to evaluate their performance in energy harvesting applications. We found that pop-up buckles and overhanging serpentine structures are suitable for audio frequency energy harvesting applications. Remarkably, almost unchanged fundamental natural frequency upon strain is achieved by properly patterning ZnO nanoribbons, which initiates a new and exciting direction of stretchable energy harvesting using nano-scale materials in audio frequency range.