bluuebunny/crossref_metadata_2025 huggingface dataset:
Inspired Chemistry for a Simple but Highly Effective Immobilization of Vascular Endothelial Growth Factor on Gallic Acid‐functionalized Plasma Polymerized Film
Authors: Yang Zhilu , Wu Jing , Wang Xin , Wang Jin , Huang Nan
Published: April 2012

Biomolecules with thiol or amine groups can be easily covalently immobilized onto a material substrate equipped with quinone groups in a simple mild alkali buffer solution based on Schiff base and Michael addition reaction. In this study we report a novel two‐step approach to creating a functional coating with abundant quinone groups for a facile immobilization of vascular endothelial growth factor (VEGF) in chemical mild phosphate buffered saline (PBS, pH = 7.4). This approach firstly involves the deposition of plasma polymerized allylamine (PPAam) thin coating onto a substrate to introduce the amine groups. Then gallic acid (3,4,5‐trihydroxybenzoic acid, GA) is chosen to functionalize PPAam for introducing phenol groups through a water‐soluble carbodiimide (WSC) coupling procedure. The results of infrared spectroscopy (IR), X‐ray photoelectron spectroscopy (XPS), and water contact angles reveal the effective conjugation of GA to PPAam and further immobilization of VEGF to GA functionalized PPAam. The results of quartz crystal microbalance equipped with dissipation monitoring (QCM‐D) show that 120 ng · cm−2 of VEGF is successfully immobilized onto GA functionalized surface. The VEGF functionalized surface shows a significant enhancement of human umbilical vein endothelial cell (HUVEC) proliferation, revealing a good bioactivity of VEGF. This functional coating not only provides a novel facile strategy for the covalent immobilization of biomolecules in a chemical mild reaction condition, but also can be adapted for a wide range of materials without surface pretreatment.

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Rock Glacier Activity in the Retezat Mountains, Southern Carpathians, Romania
Authors: Vespremeanu‐Stroe Alfred , Urdea Petru , Popescu Răzvan , Vasile Mirela
Published: April 2012

Thermal conditions in seven rock glaciers (RGs) in the Retezat Mountains were examined using ground surface temperature, the bottom temperature of snow (BTS) and late‐summer water temperature at springs. Direct current resistivity profiles were used to detect ice‐rich layers and to estimate RG volume. These parameters were supplemented by measurements of RG surface movement and morphological characteristics in order to develop a RG typology. RG activity is suggested based on BTS values and the mean annual surface temperature. The lower altitudinal limits for permafrost occurrence and the activity of RGs were found to be at 2000 m and 2100 m asl, respectively. The two highest and most active RGs are younger than 8 ka and developed following a cold climate event at 8.2 ka when a last isolated glacial episode occurred in their hosting cirques, while the remaining RGs date from 11.5–8.7 ka. Calculated rockwall denudation rates to produce these forms range from 0.8–1.1 mm/yr. Copyright © 2012 John Wiley & Sons, Ltd.
Both osteopontin‐c and osteopontin‐b splicing isoforms exert pro‐tumorigenic roles in prostate cancer cells
Authors: Tilli Tatiana M. , Mello Kivvi D. , Ferreira Luciana B. , Matos Aline R. , Accioly Maria Thereza S. , Faria Paulo A.S. , Bellahcène Akeila , Castronovo Vincent , Gimba Etel R.
Published: April 2012

BACKGROUND

Alternative splicing of the osteopontin (opn, spp1) gene generates three protein splicing isoforms (OPN‐SI), designated as OPNa, OPNb, and OPNc, which have demonstrated specific roles in different tumor models. This work aims to investigate the roles of each OPN‐SI in prostate cancer (PCa) progression by using in vivo and in vitro functional assays.

METHODS

The expression levels of OPN‐SI in prostate cell lines were analyzed by qRT‐PCR. PC‐3 was stably transfected with expression vectors containing OPNa, OPNb, and OPNc, as well as empty vector controls. PC‐3 cells overexpressing each construct were analyzed for in vivo tumor growth and in relation to different aspects mimicking tumor progression, such as cell proliferation, migration, invasion, and soft agar colony formation.

RESULTS

OPN‐SI are overexpressed in PCa as compared to non‐tumoral prostate cell lines. OPNc and OPNb overexpressing cells significantly activated enhanced xenograft tumor growth and PC‐3 proliferation, migration, invasion, and soft agar colony formation, as well as the expression of MMP‐2, MMP‐9, and VEGF. These isoforms also support sustained proliferative survival. We found that both OPNc and OPNb pro‐tumorigenic roles are mainly mediated through PI3K signaling. Inhibition of this pathway by using LY294002 specifically inhibited tumor progression features evoked by OPNc and OPNb overexpression.

CONCLUSIONS

Our data provide evidence that both OPNc and OPNb splicing isoforms promote distinct aspects of PCa progression by inducing PI3K signaling. These data give support to strategies aiming to downregulate OPNc and OPNb expression as an approach to inhibit PCa progression. Prostate 72:1688–1699, 2012. © 2012 Wiley Periodicals, Inc.
The parametric g‐formula to estimate the effect of highly active antiretroviral therapy on incident AIDS or death
Authors: Westreich Daniel , Cole Stephen R. , Young Jessica G. , Palella Frank , Tien Phyllis C. , Kingsley Lawrence , Gange Stephen J , Hernán Miguel A.
Published: April 2012

The parametric g‐formula can be used to contrast the distribution of potential outcomes under arbitrary treatment regimes. Like g‐estimation of structural nested models and inverse probability weighting of marginal structural models, the parametric g‐formula can appropriately adjust for measured time‐varying confounders that are affected by prior treatment. However, there have been few implementations of the parametric g‐formula to date. Here, we apply the parametric g‐formula to assess the impact of highly active antiretroviral therapy on time to acquired immune deficiency syndrome (AIDS) or death in two US‐based human immunodeficiency virus cohorts including 1498 participants. These participants contributed approximately 7300 person‐years of follow‐up (49% exposed to highly active antiretroviral therapy) during which 382 events occurred and 259 participants were censored because of dropout. Using the parametric g‐formula, we estimated that antiretroviral therapy substantially reduces the hazard of AIDS or death (hazard ratio = 0.55; 95% confidence limits [CL]: 0.42, 0.71). This estimate was similar to one previously reported using a marginal structural model, 0.54 (95% CL: 0.38, 0.78). The 6.5‐year difference in risk of AIDS or death was 13% (95% CL: 8%, 18%). Results were robust to assumptions about temporal ordering, and extent of history modeled, for time‐varying covariates. The parametric g‐formula is a viable alternative to inverse probability weighting of marginal structural models and g‐estimation of structural nested models for the analysis of complex longitudinal data. Copyright © 2012 John Wiley & Sons, Ltd.
Use of pooled samples from the national health and nutrition examination survey
Authors: Caudill Samuel P.
Published: April 2012

The National Centers for Disease Control and Prevention (CDC) provides an ongoing assessment of the US population's exposure to environmental chemicals by using biomonitoring in conjunction with CDC's National Health and Nutrition Examination Survey (NHANES). Characterizing the distributions of concentrations of environmental compounds or their metabolites in the US population is a primary objective of CDC's biomonitoring program. Historically, this characterization has been based on individual measurements of these compounds in body fluid or tissue from representative samples of the population. Pooling samples before making analytical measurements can reduce the costs of biomonitoring by reducing the number of analyses. For the first time in NHANES 2005–2006, a weighted pooled‐sample design was implemented to facilitate pooling samples before making analytical measurements. This paper describes this design and the estimation method being developed in the National Center for Environmental Health, Division of Laboratory Sciences (NCEH/DLS) to characterize concentrations of polychlorinated and polybrominated compounds. We present percentile estimates for 2,2  ′ ,4,4  ′ ,5,5  ′ ‐hexachlorobiphenyl (PCB153) in specific subpopulations of the US based on the NHANES 2005–2006 pooled‐sample design. We also compare estimates based on individual samples from NHANES 2003–2004 with estimates based on artificially created pools from NHANES 2003–2004 using a pooled‐sample design similar to the one used for NHANES 2005–2006. For NHANES 2005–2006 the number of analyses required to characterize the levels of 61 polychlorinated and 13 polybrominated compounds in the US population was reduced from 2201 to 228. At a cost of $1400 per analytical measurement, this represents a savings of approximately $2.78 million. Published 2012. This article is a US Government work and is in the public domain in the USA.
Enhancing the Jacquez k nearest neighbor test for space–time interaction
Authors: Malizia Nicholas , Mack Elizabeth A.
Published: April 2012

The Jacquez k nearest neighbor test, originally developed to improve upon shortcomings of existing tests for space–time interaction, has been shown to be a robust and powerful method of detecting interaction. Despite its flexibility and power, however, the test has three main shortcomings: (i) it discards important information regarding the spatial and temporal scales at which the detected interaction takes place; (ii) the results of the test have not been visualized; and (iii) recent research demonstrates the test to be susceptible to population shift bias. This study presents enhancements to the Jacquez k nearest neighbors test with the goal of addressing each of these three shortcomings and of improving the utility of the test. Data on Burkitt's lymphoma cases in Uganda between 1961 and 1975 are used to illustrate the modifications and enhanced visual output of the test. Output from the enhanced test is compared with that provided by alternative tests of space–time interaction. Results show the enhancements presented in this study transform the Jacquez test into a complete, descriptive, and informative metric that can be used as a stand‐alone measure of global space–time interaction. Copyright © 2012 John Wiley & Sons, Ltd.
A simple sample size formula for analysis of covariance in cluster randomized trials
Authors: Teerenstra Steven , Eldridge Sandra , Graff Maud , de Hoop Esther , Borm George F.
Published: April 2012

For cluster randomized trials with a continuous outcome, the sample size is often calculated as if an analysis of the outcomes at the end of the treatment period (follow‐up scores) would be performed. However, often a baseline measurement of the outcome is available or feasible to obtain. An analysis of covariance (ANCOVA) using both the baseline and follow‐up score of the outcome will then have more power. We calculate the efficiency of an ANCOVA analysis using the baseline scores compared with an analysis on follow‐up scores only. The sample size for such an ANCOVA analysis is a factor r2 smaller, where r is the correlation of the cluster means between baseline and follow‐up. This correlation can be expressed in clinically interpretable parameters: the correlation between baseline and follow‐up of subjects (subject autocorrelation) and that of clusters (cluster autocorrelation). Because of this, subject matter knowledge can be used to provide (range of) plausible values for these correlations, when estimates from previous studies are lacking. Depending on how large the subject and cluster autocorrelations are, analysis of covariance can substantially reduce the number of clusters needed. Copyright © 2012 John Wiley & Sons, Ltd.
On the equivalence of posterior inference based on retrospective and prospective likelihoods: application to a case‐control study of colorectal cancer
Authors: Ghosh M. , Song J. , Forster J.J. , Mitra R. , Mukherjee B.
Published: April 2012

The paper develops a class of priors that leads to equivalent posterior inference for odds ratio parameters based on prospective and retrospective models for categorical response data. The results are applicable to both unmatched and matched case‐control studies. The results hold for a general class of link functions for categorical response. The proposed method can accommodate multiple and possibly ordered disease states. The results are applied to the analysis of discrete subtypes in an ongoing case‐control study of colorectal cancer. A simulation study illustrates the need for carefully considering prior choices in Bayesian analysis of data collected under retrospective design. Copyright © 2012 John Wiley & Sons, Ltd.
Effects of Chewing Gum on Stress and Health: A Replication and Investigation of Dose–Response
Authors: Smith Andrew
Published: April 2012

Research suggests that chewing gum may be associated with reduced stress, depression and a reduced likelihood of having high cholesterol and blood pressure. The present study aimed to replicate these findings and extend them by examining dose–response. A web‐based survey was completed by a sample of 388 workers from public sector organisations (68.5% female; mean age: 42 years, range 17–64 years). The results showed that chewing gum was associated in a linear dose–response manner with lower levels of perceived stress (both at work and life in general), anxiety and depression. Occasional gum chewers also reported a reduced risk of high cholesterol and blood pressure. Intervention studies are now required to extend these findings, and the mechanisms underlying the effects reported here need further investigation. Copyright © 2012 John Wiley & Sons, Ltd.
2d affine XY-spin model/4d gauge theory duality and deconfinement
Authors: Anber Mohamed M. , Poppitz Erich , Ünsal Mithat
Published: April 2012

Abstract

We introduce a duality between two-dimensional XY-spin models with symmetry-breaking perturbations and certain four-dimensional SU(2) and SU(2)/
$ {\mathbb{Z}_2} $
gauge theories, compactified on a small spatial circle
$ {\mathbb{R}^{{^{{{1},{2}}}}}} $
×
$ {\mathbb{S}^{{^{{1}}}}} $
, and considered at temperatures near the deconfinement transition. In a Euclidean set up, the theory is defined on
$ {\mathbb{R}^{{^{{2}}}}} $
×
$ {\mathbb{T}^{{^{{2}}}}} $
. Similarly, thermal gauge theories of higher rank are dual to new families of “affine” XY-spin models with perturbations. For rank two, these are related to models used to describe the melting of a 2d crystal with a triangular lattice. The connection is made through a multi-component electric-magnetic Coulomb gas representation for both systems. Perturbations in the spin system map to topological defects in the gauge theory, such as monopole-instantons or magnetic bions, and the vortices in the spin system map to the electrically charged W-bosons in field theory (or vice versa, depending on the duality frame). The duality permits one to use the two-dimensional technology of spin systems to study the thermal deconfinement and discrete chiral transitions in four-dimensional SU(N

c
) gauge theories with n

f
≥1 adjoint Weyl fermions.
Changing Museum Visitors’ Conceptions of Evolution
Authors: Spiegel Amy N. , Evans E. Margaret , Frazier Brandy , Hazel Ashley , Tare Medha , Gram Wendy , Diamond Judy
Published: April 2012

We examined whether a single visit to an evolution exhibition contributed to conceptual change in adult (n = 30), youth, and child (n = 34) museum visitors’ reasoning about evolution. The exhibition included seven current research projects in evolutionary science, each focused on a different organism. To frame this study, we integrated a developmental model of visitors’ understanding of evolution, which incorporates visitors’ intuitive beliefs, with a model of free-choice learning that includes personal, sociocultural, and contextual variables. Using pre- and post-measures, we assessed how visitors’ causal explanations about biological change, drawn from three reasoning patterns (evolutionary, intuitive, and creationist), were modified as a result of visiting the exhibition. Whatever their age, background beliefs, or prior intuitive reasoning patterns, visitors significantly increased their use of explanations from the evolutionary reasoning pattern across all measures and extended this reasoning across diverse organisms. Visitors also increased their use of one intuitive reasoning pattern, need-based (goal-directed) explanations, which, we argue, may be a step toward evolutionary reasoning. Nonetheless, visitors continued to use mixed reasoning (endorsing all three reasoning patterns) in explaining biological change. The personal, socio-cultural, and contextual variables were found to be related to these reasoning patterns in predictable ways. These findings are used to examine the structure of visitors’ reasoning patterns and those aspects of the exhibition that may have contributed to the gains in museum visitors’ understanding of evolution.
Socio-Environmental Health Analysis in Nogales, Sonora, Mexico
Authors: Norman Laura M. , Caldeira Felipe , Callegary James , Gray Floyd , O’ Rourke Mary Kay , Meranza Veronica , Van Rijn Saskia
Published: April 2012

In Nogales, Sonora, Mexico, some neighborhoods, or colonias, have intermittent delivery of water through pipes from the city of Nogales’s municipal water-delivery system while other areas lack piped water and rely on water delivered by truck or pipas. This research examined how lifestyles, water quality, and potential disease response, such as diarrhea, differs seasonally from a colonia with access to piped water as opposed to one using alternative water-delivery systems. Water samples were collected from taps or spigots at homes in two Nogales colonias. One colonia reflected high socio-environmental conditions where residents are supplied with municipal piped water (Colonia Lomas de Fatima); the second colonia reflected low socio-environmental conditions, lacking access to piped water and served by pipas (Colonia Luis Donaldo Colosio). A survey was developed and implemented to characterize perceptions of water quality, health impacts, and quality of life. Water samples were analyzed for microbial and inorganic water-quality parameters known to impact human health including, Escherichia coli (E. coli), total coliform bacteria, arsenic, and lead. A total of 21 households agreed to participate in the study (14 in Colosio and 7 in Fatima). In both colonias metal concentrations from water samples were all well below the United States Environmental Protection Agency’s (US EPA’s) maximum contaminant levels. E. coli concentrations exceeded the US EPA’s drinking-water standard in Colosio but not Fatima. Total coliform bacteria were present in over 50 % of households in both colonias. Microbial contamination was significantly higher in the summer than in the winter in both colonias. Resulting analysis suggests that residents in colonias without piped water are at a greater risk of gastrointestinal illness from consumption of compromised drinking water. Our survey corroborated reports of gastrointestinal illness in the summer months but not in the winter. Chloride was found to be significantly greater in Colosio (median 29.2 mg/L) although still below the US EPA’s maximum contaminant levels of 250 mg/L. Ongoing binational collaboration can promote mechanisms to improve water quality in cities located in the US–Mexico border.
Recycling gone bad: When the option to recycle increases resource consumption
Authors: Catlin Jesse R. , Wang Yitong
Published: April 2012

In this study, we propose that the ability to recycle may lead to increased resource usage compared to when a recycling option is not available. Supporting this hypothesis, our first experiment shows that consumers used more paper while evaluating a pair of scissors when the option to recycle was provided (vs. not provided). In a follow‐up field experiment, we find that the per person restroom paper hand towel usage increased after the introduction of a recycling bin compared to when a recycling option was not available. We conclude by discussing implications for research and policy.
Transformation of temporomandibular joint disc configuration in internal derangement patients using magnetic resonance imaging
Authors: Arayasantiparb Raweewan , Tsuchimochi Makoto , Mitrirattanakul Somsak
Published: April 2012

Purpose: The normal disc configuration is biconcave; however, the deformed disc can be found in internal derangement (ID) of the temporomandibular joint (TMJ). The purpose of this study was to evaluate the relationship between the transformation patterns of TMJ disc configuration during mouth opening and disc displacement status, disc reduction ability and TMJ clinical symptoms.

Methods: TMJ MR images from volunteers and ID patients were analyzed for closed and open mouth positions. MR images of ID patients were classified into 4 groups: symptomatic joint with anterior disc displacement with or without reduction (ADW or ADWo) and asymptomatic joint with ADW or ADWo. The disc configurations in both positions were categorized as biconcave, biplanar, convex or folded; then the patterns of transformation were observed.

Results: For the ADW group, the most common disc configuration for closed and open mouth positions were biplanar (66.7%) and biconcave (86.3%). The transformation pattern was significantly related to disc reduction ability (p < 0.05).

Conclusions: The transformation patterns of disc configuration during opening were related to anterior disc displacement and disc reduction ability.
Equation of motion for a sphere in non-uniform compressible flows
Authors: Parmar M. , Haselbacher A. , Balachandar S.
Published: April 2012

Linearized viscous compressible Navier–Stokes equations are solved for the transient force on a spherical particle undergoing unsteady motion in an inhomogeneous unsteady ambient flow. The problem is formulated in a reference frame attached to the particle and the force contributions from the undisturbed ambient flow and the perturbation flow are separated. Using a density-weighted velocity transformation and reciprocal relation, the total force is first obtained in the Laplace domain and then transformed to the time domain. The total force is separated into the quasi-steady, inviscid unsteady, and viscous unsteady contributions. The above rigorously derived particle equation of motion can be considered as the compressible extension of the Maxey–Riley–Gatignol equation of motion and it incorporates interesting physics that arises from the combined effects of inhomogeneity and compressibility.
A new model of roll waves: comparison with Brock’s experiments
Authors: Richard G. L. , Gavrilyuk S. L.
Published: April 2012

We derive a mathematical model of shear flows of shallow water down an inclined plane. The non-dissipative part of the model is obtained by averaging the incompressible Euler equations over the fluid depth. The averaged equations are simplified in the case of weakly sheared flows. They are reminiscent of the compressible non-isentropic Euler equations where the flow enstrophy plays the role of entropy. Two types of enstrophies are distinguished: a small-scale enstrophy generated near the wall, and a large-scale enstrophy corresponding to the flow in the roller region near the free surface. The dissipation is then added in accordance with basic physical principles. The model is hyperbolic, the corresponding ‘sound velocity’ depends on the flow enstrophies. Periodic stationary solutions to this model describing roll waves were obtained. The solutions are in good agreement with the experimental profiles of roll waves measured in Brock’s experiments. In particular, the height of the vertical front of the waves, the shock thickness and the wave amplitude are well captured by the model.
ASSOCIATIONS BETWEEN HOUSEHOLD AND NEIGHBOURHOOD SOCIOECONOMIC STATUS AND SYSTOLIC BLOOD PRESSURE AMONG URBAN SOUTH AFRICAN ADOLESCENTS
Authors: GRIFFITHS PAULA L. , SHEPPARD ZOË A. , JOHNSON WILLIAM , CAMERON NOËL , PETTIFOR JOHN M. , NORRIS SHANE A.
Published: April 2012

Factors resulting in high risk for cardiovascular disease have been well studied in high income countries, but have been less well researched in low/middle income countries. This is despite robust theoretical evidence of environmental transitions in such countries which could result in biological adaptations that lead to increased hypertension and cardiovascular disease risk. Data from the South African Birth to Twenty cohort, Bone Health sub-sample (n=358, 47% female), were used to model associations between household socioeconomic status (SES) in infancy, household/neighbourhood SES at age 16 years, and systolic blood pressure (multivariate linear regression) and risk for systolic pre-hypertension (binary logistic regression). Bivariate analyses revealed household/neighbourhood SES measures that were significantly associated with increased systolic blood pressure. These significant associations included improved household sanitation in infancy/16 years, caregiver owning the house in infancy and being in a higher tertile (higher SES) of indices measuring school problems/environment or neighbourhood services/problems/crime at 16 years of age. Multivariate analyses adjusted for sex, maternal age, birth weight, parity, smoking, term birth, height/body mass index at 16 years. In adjusted analyses, only one SES variable remained significant for females: those in the middle tertile of the crime prevention index had higher systolic blood pressure (β=3.52, SE=1.61) compared with the highest tertile (i.e. those with the highest crime prevention). In adjusted analyses, no SES variables were significantly associated with the systolic blood pressure of boys, or with the risk of systolic pre-hypertension in either sex. The lack of association between SES and systolic blood pressure/systolic pre-hypertension at age 16 years is consistent with other studies showing an equalization of adolescent health inequalities. Further testing of the association between SES and systolic blood pressure would be recommended in adulthood to see whether the lack of association persists.
Changes in severity of depressive symptoms and mortality: the Italian Longitudinal Study on Aging
Authors: Scafato E. , Galluzzo L. , Ghirini S. , Gandin C. , Rossi A. , Solfrizzi V. , Panza F. , Di Carlo A. , Maggi S. , Farchi G.
Published: April 2012

Background

Depression is recognized as being associated with increased mortality. However, there has been little previous research on the impact of longitudinal changes in late-life depressive symptoms on mortality, and of their remission in particular.

Method

As part of a prospective, population-based study on a random sample of 5632 subjects aged 65–84 years, with a 10-year follow-up of vital status, depressive symptoms were assessed by the 30-item Italian version of the Geriatric Depression Scale (GDS). The number of participants in the GDS measurements was 3214 at baseline and 2070 at the second survey, 3 years later. Longitudinal changes in depressive symptoms (stable, remitted, worsened) were examined in participants in both evaluations (n=1941). Mortality hazard ratios (MHRs) according to severity of symptoms and their changes over time were obtained by means of Cox proportional hazards regression models, adjusting for age and other potentially confounding factors.

Results

Severity is significantly associated with excess mortality in both genders. Compared to the stability of depressive symptoms, a worsened condition shows a higher 7-year mortality risk [MHR 1.46, 95% confidence interval (CI) 1.15–1.84], whereas remission reduces by about 40% the risk of mortality in both genders (women MHR 0.55, 95% CI 0.32–0.95; men MHR 0.59, 95% CI 0.37–0.93). Neither sociodemographic nor medical confounders significantly modified these associations.

Conclusions

Consistent with previous reports, the severity and persistence of depression are associated with higher mortality risks. Our findings extend the magnitude of the association demonstrating that remission of symptoms is related to a significant reduction in mortality, highlighting the need to enhance case-finding and successful treatment of late-life depression.
Quality of life among disabled older adults without cognitive impairment and its relation to attendance in day care centres
Authors: IECOVICH ESTHER , BIDERMAN AYA
Published: April 2012

Day care centres intend to improve the quality of life of disabled older adults. The aims of the paper are to: (a) examine the extent to which users of day care centres experience higher levels of quality of life compared to their peers who are non-users; and (b) to explore the relationships between the length of use and frequency of weekly attendance at day care centres and quality of life. This is a case-control study with a sample of 817 respondents, of whom 417 were users of day care centres and 400 were non-users, matched by age, gender and family physician. The study was conducted in 12 day care centres in the southern region of Israel. Data collection included face-to-face interviews using a structured questionnaire. Quality of life was found to be significantly related to the use of day care centres, but length and frequency of attendance were insignificant in explaining quality of life among users of day care centres. The study demonstrated that users of day care centres have a higher quality of life, but in a cross-sectional study we cannot prove causality. Therefore, more research using quasi-experimental and longitudinal research designs is necessary to assess causality between use and attendance at day care centres on users' quality of life.
Rethinking epistemic communities twenty years later
Authors: CROSS MAI'A K. DAVIS
Published: April 2012

The concept of epistemic communities – professional networks with authoritative and policy-relevant expertise – is well-known thanks to a 1992 special issue ofInternational Organization. Over the past twenty years, the idea has gained some traction in International Relations scholarship, but has not evolved much beyond its original conceptualisation. Much of the research on epistemic communities has been limited to single case studies in articles, rather than broader comparative works, and has focused narrowly on groups of scientists. As a result, it is often assumed, erroneously, that epistemic communities are only comprised of scientists, and that the utility of the concept for understanding International Relations is quite narrow. Consequently, an otherwise promising approach to transnational networks has become somewhat marginalised over the years. This article revisits the concept of epistemic communities twenty years later and proposes specific innovations to the framework. In an increasingly globalising world, transnational actors are becoming progressively more numerous and influential. Epistemic communities are certainly at the forefront of these trends, and a better understanding of how they form and operate can give us a clear demonstration of how knowledge translates into power.
Responsible reconstruction after war: meeting local needs for building peace
Authors: CUBITT CHRISTINE
Published: April 2012

Contemporary peacebuilding operations are often mandated to rebuild ‘collapsed’ or weak states and provide unique opportunities for internationals to exert far reaching influence in their reconstruction. The responsibility to help secure peaceful transformations and longer term stability is profound. This article explores the issue of efficacy and propriety in reconstruction programming and draws from field work in Sierra Leone – a rare example of ‘success’ for international partners in peacebuilding missions. The assertion is made that, despite the euphoria over the mission in Sierra Leone, the peacebuilding operations were more about the mechanics of statebuilding than the local politics of building peace, and that there was a distinct disconnect between the policy rhetoric and the policy practice. The argument is put that the pressing local concern of giving citizens a stake in government was not best served in the reconstruction project because the wider and more influential objectives of the peacebuilding mission were about meeting international goals not local aspirations. This reality has come at the cost of exploiting a unique opportunity for creative thinking about the kind of state structures which can better address the main challenges for sustainable peace facing post-war states like Sierra Leone.
Granitic batholiths: from pervasive and continuous melting in the lower crust to discontinuous and spaced plutonism in the upper crust
Authors: Vigneresse Jean Louis
Published: April 2012

The generation of granitic magmas begins with melting in the lower crust, under active participation of the underlying mantle. Thermally driven, melting is a pervasive and continuous process that develops over a wide region. In contrast, the building of a granitic pluton is highly discontinuous in time and space. Several inputs of magma, sometimes with a different chemical compositions, are focused toward a region where they accumulate, forming a large pluton, often separated by some 50 km from an adjacent one. The switch from a continuous to a discontinuous process represents a fundamental point of magma generation. It gives place to the modified model m(M-SAE), in which the mantle (m) and Melting (M) are separated from the Segregation (S), Ascent (A) and Emplacement (E) modes. Discontinuities result from non-linear processes that develop during segregation and ascent of the magma. They rely on the non-linear rheology of partially molten rocks. Thresholds control the change from a solid-like to liquid-like behaviour of the magma. In between, the rheology exhibits sudden jumps between states. Because two phases continuously coexist (matrix and melt), strain is highly partitioned between them. This may induce highly discontinuous melt segregation, which needs both pure and simple shear to develop. Melt focusing is controlled by the viscosity contrast between the two phases. It gives rise to different compaction lengths depending on the region, a partially melting source or a nearly brittle crust, where it develops. Because ascent and emplacement are discontinuous in time, this allows the crust to relax, avoiding the room problem for a pluton intruding the upper crust. Intermediate magma chambers could develop with different temperature and magma composition. They could be the place of enhanced magma mixing. Finally, the stress conditions, which differ for each tectonic setting, influence the shape of the granitic body.
The economic potential of payments for ecosystem services in water conservation: a case study in the upper reaches of Shiyang River basin, northwest China
Authors: Tang Zeng , Shi Yulan , Nan Zhibiao , Xu Zhongmin
Published: April 2012

In this paper, we conduct an investigation to assess the economic potential of payments for ecosystem services to conserve water through the conversion of land under irrigation into rain-fed land in the upper reaches of the Shiyang River basin, located in northwest China. We use an approach developed by Antle and Valdivia (2006, Australian Journal of Agricultural and Resource Economics, 50: 1–15) to estimate the supply of water. The analysis shows that it is theoretically possible to reduce agricultural water consumption and subsequently increase the water supply, which would aid the prevention of environmental degradation in the middle and lower reaches of the Shiyang River basin. In addition to the conservation of water, considerable income would be generated by local farmers, which would help to alleviate poverty. Furthermore, the analysis also suggests that more complete data on ecosystem services rates, transaction costs and other related factors would be of value for achieving a more comprehensive assessment.
Prenatal growth and metabolic syndrome components among Chilean children
Authors: Mardones F. , Villarroel L. , Arnaiz P. , Barja S. , Domínguez A. , Castillo O. , Farías M. , Eriksson J. G. , Pacheco P.
Published: April 2012

The association of prenatal growth with metabolic syndrome (MS) components and insulin resistance (IR) in children has not been studied in Chile and most developing countries. Some associations found in developed countries are controversial. A retrospective cohort study was designed linking present information on MS components and IR in children with register-based information on birth weight (BW), birth length (BL) and gestational age (GA). Examinations included anthropometry and blood pressure (BP), as well as self-report of pubertal status. A fasting blood sample was taken to determine lipids, glucose, insulin and homeostasis model assessment (HOMA)-IR was calculated. The study cohort of 2152 children was on average 11.4 ± 1.0 years old. The prevalence of MS, IR and overweight were 7.6%, 24.5% and 34%, respectively. Elevated BP was negatively associated with dichotomized risk categories of the perinatal factors studied (BW, BL and GA). Contingency tables showed that high waist circumference (WC) and elevated BP had a U-shaped association with various categories of BW and BL, respectively. Stepwise linear regressions selected: (a) WC as inversely associated to GA and directly associated to BW, (b) BP as inversely associated to GA and (c) HOMA-IR as inversely associated to BL. Non-optimal prenatal growth seems to predispose to high WC, elevated BP and IR in school-age children, supporting the early life origin of several non-communicable diseases. Those associations were rather weak as estimated by the slopes of the regressions and probably reduced by their U-shaped nature; they would reasonably become stronger with a longer follow-up.
Solar EUV and XUV energy input to thermosphere on solar rotation time scales derived from photoelectron observations
Authors: Peterson W. K. , Woods T. N. , Fontenla J. M. , Richards P. G. , Chamberlin P. C. , Solomon S. C. , Tobiska W. K. , Warren H. P.
Published: April 2012

Solar radiation below ∼100 nm produces photoelectrons, a substantial portion of the F region ionization, most of the E region ionization, and drives chemical reactions in the thermosphere. Unquantified uncertainties in thermospheric models exist because of uncertainties in solar irradiance models used to fill spectral and temporal gaps in solar irradiance observations. We investigate uncertainties in solar energy input to the thermosphere on solar rotation time scales using photoelectron observations from the FAST satellite. We compare observed and modeled photoelectron energy spectra using two photoelectron production codes driven by five different solar irradiance models. We observe about 1.7% of the ionizing solar irradiance power in the escaping photoelectron flux. Most of the code/model pairs used reproduce the average escaping photoelectron flux over a 109‐day interval in late 2006. The code/model pairs we used do not completely reproduce the observed spectral and solar rotation variations in photoelectron power density. For the interval examined, 30% of the variability in photoelectron power density with equivalent wavelengths between 18 and 45 nm was not captured in the code/model pairs. For equivalent wavelengths below ∼16 nm, most of the variability was missed. This result implies that thermospheric model runs based on the solar irradiance models we tested systematically underestimate the energy input from ionizing radiation on solar rotation time scales.
Sensitivity of the short‐ to intermediate‐wavelength geoid to rheologic structure in subduction zones
Authors: Hines Joy M. , Billen Magali I.
Published: April 2012

The rheologic structure of subduction zones determines how the negative buoyancy of sinking lithosphere (slabs) couples to the surface to cause surface deformation and plate motion. However, the rheologic structures determined using different methods are inconsistent. Analysis of the geoid and some dynamical models conclude that slabs must be weak, whereas other dynamical models and experimentally determined rheology predict that slabs are strong. Using idealized three‐dimensional models of a subduction zone, we show that lateral variations in viscosity (LVVs) within a slab caused by yielding render the geoid insensitive to the viscosity structure outside of the bending region of the slab. Spectral analysis of the geoid up to harmonic degree 360 (features at wavelengths down to 110 km) shows that LVVs cause significant mode coupling with changes to the long‐wavelength geoid (>1000 km) caused by short‐wavelength (<500 km) changes to dynamic topography. Models with either a uniformly weak slab, or a strong slab with yielding, provide a good match to the observed geoid spectrum and characteristic features of the geoid over subduction zones. Therefore, observations other than the geoid are needed to constrain the strength profile of subducting slabs.
Horizontal transport affecting trace gas seasonality in the Tropical Tropopause Layer (TTL)
Authors: Ploeger F. , Konopka P. , Müller R. , Fueglistaler S. , Schmidt T. , Manners J. C. , Grooß J.‐U. , Günther G. , Forster P. M. , Riese M.
Published: April 2012

We analyze horizontal transport from midlatitudes into the tropics (in‐mixing) and its impact on seasonal variations of ozone, carbon monoxide and water vapor in the Tropical Tropopause Layer (TTL). For this purpose, we use three‐dimensional backward trajectories, driven by ECMWF ERA‐Interim winds, and a conceptual one‐dimensional model of the chemical composition of the TTL. We find that the fraction of in‐mixed midlatitude air shows an annual cycle with maximum during NH summer, resulting from the superposition of two inversely phased annual cycles for in‐mixing from the NH and SH, respectively. In‐mixing is driven by the monsoonal upper‐level anticyclonic circulations. This circulation pattern is dominated by the Southeast Asian summer monsoon and, correspondingly, in‐mixing shows an annual cycle. The impact of in‐mixing on TTL mixing ratios depends on the in‐mixed fraction of midlatitude air and on the meridional gradient of the particular species. For CO the meridional gradient and consequently the effect of in‐mixing is weak. For water vapor, in‐mixing effects are negligible. For ozone, the meridional gradient is large and the contribution of in‐mixing to the ozone maximum during NH summer is about 50%. This in‐mixing contribution is not sensitive to the tropical ascent velocity, which is about 40% too fast in ERA‐Interim. As photochemically produced ozone in the TTL shows no distinct summer maximum, the ozone annual anomaly in the upper TTL turns out to be mainly forced by in‐mixing of ozone‐rich extratropical air during NH summer.
A technique using principal component analysis to compare seasonal cycles of Earth radiation from CERES and model computations
Authors: Smith G. Louis , Mlynczak Pamela E. , Potter Gerald L.
Published: April 2012

A method for quantitatively comparing the seasonal cycles of two global data sets is presented. The seasonal cycles of absorbed solar radiation (ASR) and outgoing longwave radiation (OLR) have been computed from an eight‐year data set from the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers and from a model data set produced by the NASA Goddard Space Flight Center Global Modeling and Assimilation Office. To compare the seasonal cycles from these two data sets, principal component (PC) analysis is used, where the PCs express the time variations and the corresponding empirical orthogonal functions (EOFs) describe the geographic variations. Ocean has a long thermal response time compared to land, so land and ocean are separated for the analysis. The root‐mean square values for the seasonal cycles of ASR and OLR are extremely close for the two data sets. The first three PCs are quite close, showing that the time responses and magnitudes over the globe are very similar. The agreement between the two sets of PCs is quantified by computing the matrix of inner products of the two sets. For ASR over land, the first PCs of CERES and the model agree to better than 99.9%. The EOF maps are similar for most of the globe, but differ in a few places, and the agreement of the EOF maps is likewise quantified. Maps of differences between the annual cycles show regions of agreement and disagreement.
Boundary stresses due to impacts from dry granular flows
Authors: Yohannes Bereket , Hsu L. , Dietrich W. E. , Hill K. M.
Published: April 2012

Field data and laboratory experiments suggest that bedrock wear from debris flows is largely due to particle–bed impacts, rather than solely due to abrasion by sliding, and that the associated bedrock erosion rates are dependent on the particle size distribution in the debris flow. Here we use Discrete Element Method (DEM) simulations with an established contact mechanics model to explore grain‐size influences on contact forces associated with particle–bed impacts in sheared granular mixtures. We first compare DEM simulations with experimental observations obtained from shallow granular flows in rotating drums of diameters 0.56 m and 4.0 m. Our simulations reproduce, without parameter tuning, experimentally measured segregation, boundary pressures, and height profiles. We perform additional simulations systematically varying particle size distributions in binary mixtures. We show that local time‐averaged boundary pressures in thin flows are essentially the normal component of the weight of the flow, independent of particle size distribution. However, other statistical measures of boundary forces scale with mass‐averaged particle size. We demonstrate that this is because individual particle–bed impacts, rather than impacts from multiple particle collisions, dominate the largest contact forces. We show that these largest impact forces vary as the square of grain size and the 1.2 power of impact velocity as predicted from the contact mechanics model underlying the DEM. These results support the particle size dependence of a recently proposed bedrock incision model and suggest that next steps for a predictive bedrock incision model require the statistics of the largest impact velocities.
Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth
Authors: Reitz Meredith D. , Jerolmack Douglas J.
Published: April 2012

River deltas and alluvial fans have channelization and deposition dynamics that are not entirely understood, but which dictate the evolution of landscapes of great social, economic, and ecologic value. Our lack of a process‐based understanding of fan dynamics hampers our ability to construct accurate prediction and hazard models, leaving these regions vulnerable. Here we describe the growth of a series of experimental alluvial fans composed of a noncohesive grain mixture bimodal in size and density. We impose conditions that simulate a gravel/sand fan prograding into a static basin with constant water and sediment influx, and the resulting fans display realistic channelization and avulsion dynamics. We find that we can describe the dynamics of our fans in terms of a few processes: (1) an avulsion sequence with a timescale dictated by mass conservation between incoming flux and deposit volume; (2) a tendency for flow to reoccupy former channel paths; and (3) bistable slopes corresponding to separate entrainment and deposition conditions for grains. Several important observations related to these processes are: an avulsion timescale that increases with time and decreases with sediment feed rate; fan lobes that grow in a self‐similar, quasi‐radial pattern; and channel geometry that is adjusted to the threshold entrainment stress. We propose that the formation of well‐defined channels in noncohesive fans is a transient phenomenon resulting from incision following avulsion, and can be directly described with dual transport thresholds. We present a fairly complete, process‐based description of the mechanics of avulsion and its resulting timescale on our fans. Because the relevant dynamics depend only on threshold transport conditions and conservation of mass, we show how results may be directly applied to field‐scale systems.