bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of different irrigation protocols concerning the formation of chemical smear layer
Authors: Do Prado Maíra , Simão Renata A. , Gomes Brenda P.F.A.
Published: December 2012

The aim of this work was to evaluate, by means of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS), the different irrigation protocols concerning the formation of chemical smear layer (CSL). Fifty‐five teeth were instrumented by using distilled water (DW) as irrigant. Next, the teeth were submitted to a protocol for removal of the mechanical smear layer produced. The teeth were divided into 11 groups, according to irrigation regimen. Then, the teeth were prepared and analyzed with SEM and EDS. Only in Group 1 [1 mL sodium hypochlorite (NaOCl) + 10 mL DW + 1 mL chlorhexidine (CHX) solution], Group 2 [1 mL NaOCl + 10 mL DW + 1 mL ethylenediaminetetraacetic acid (EDTA) + 10 mL DW + 1 mL CHX solution], and Group 3 [1 mL NaOCl + 10 mL DW + 1 mL citric acid (CA) + 10 mL DW + 1 mL CHX solution], the formation of CSL was observed. In the groups where CHX gel was used alone or in association with EDTA, CA, phosphoric acid (PA), and CHX solution, no formation of CSL was observed. According to the results found in the cases in which one wants to associate NaOCl with CHX, the protocol using PA (1 mL NaOCl + 10 mL DW + 1 mL PA + 10 mL DW + 1 mL CHX solution) did not induce formation of CSL. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.
Explaining task performance and creativity from perceived organizational support theory: Which mechanisms are more important?
Authors: Yu Chongxin , Frenkel Stephen J.
Published: December 2012

Perceived organizational support (POS) theory specifies three mechanisms—felt obligation, group identification, and outcome expectancy—to explain the effects of organizational support on employee work outcomes. These mechanisms have usually been examined in isolation so that it is not possible to assess their relative explanatory power. The present study aims to remedy this problem by examining the three mechanisms simultaneously using structural equation modeling. On the basis of a sample of 206 bank employees in China, we focus on two types of employee performance—task performance and creativity—as dependent variables. Drawing on self‐determination theory and characteristics of the research context, we propose that task performance is more strongly predicted by felt obligation than by the other two mechanisms, whereas identification and expectancy more strongly predict creativity than felt obligation. We conclude by discussing our contribution to POS and creativity research, and highlight some important implications of our findings. Copyright © 2012 John Wiley & Sons, Ltd.
Characterization and quantification of triacylglycerols in peanut oil by off‐line comprehensive two‐dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry
Authors: Hu Jun , Wei Fang , Dong Xu‐Yan , Lv Xin , Jiang Mu‐Lan , Li Guang‐Ming , Chen Hong
Published: December 2012

The complexity of natural triacylglycerols (TAGs) in various edible oils is prodigious due to the hundreds of set is of TAG compositions, which makes the identification of TAGs quite difficult. In this investigation, the off‐line 2D system coupling of nonaqueous RP and silver‐ion HPLC with atmospheric pressure chemical ionization MS detection has been applied to the identification and quantification of TAGs in peanut oil. The method was successful in the separation of a high number of TAG solutes, and the TAG structures were evaluated by analyzing their atmospheric pressure chemical ionization mass spectra information. HPLC and MS conditions have been optimized and the fragmentation mechanisms of isomers have been validated. In addition, an internal standard approach has been developed for TAG quantification. Then this system was applied in peanut oil samples and there was a total of 48 TAGs including regioisomers that have been determined and quantified.
Impact of Evidence‐Based Standardized Assessment on the Disability Clinical Interview for Diagnosis of Service‐Connected PTSD: A Cluster‐Randomized Trial
Authors: Speroff Theodore , Sinnott Patricia L. , Marx Brian , Owen Richard R. , Jackson James C. , Greevy Robert , Sayer Nina , Murdoch Maureen , Shane Andrea C. , Smith Jeffrey , Alvarez JoAnn , Nwosu Samuel K. , Keane Terence , Weathers Frank , Schnurr Paula P. , Friedman Matthew J.
Published: December 2012

Posttraumatic stress disorder (PTSD) is one of the fastest growing compensated medical conditions. The present study compared usual disability examiner practices for PTSD with a standardized assessment that incorporates evidence‐based assessments. The design was a multicenter, cluster randomized, parallel‐group study involving 33 clinical examiners and 384 veterans at 6 Veterans Affairs medical centers. The standardized group incorporated the Clinician Administered PTSD Scale and the World Health Organization Disability Assessment Schedule‐II into their assessment interview. The main outcome measures were completeness and accuracy of PTSD diagnosis and completeness of functional assessment. The standardized assessments were 85% complete for diagnosis compared to 30% for nonstandardized assessments (p < .001), and, for functional impairment, 76% versus 3% (p < .001). The findings demonstrate that the quality of PTSD disability examination would be improved by using evidence‐based assessment.
Stress, Mental Health, and Burnout in National Humanitarian Aid Workers in Gulu, Northern Uganda
Authors: Ager Alastair , Pasha Eba , Yu Gary , Duke Thomas , Eriksson Cynthia , Cardozo Barbara Lopes
Published: December 2012

This study examined the mental health of national humanitarian aid workers in northern Uganda and contextual and organizational factors predicting well‐being. A cross‐sectional survey was conducted among 376 national staff working for 21 humanitarian aid agencies. Over 50% of workers experienced 5 or more categories of traumatic events. Although, in the absence of clinical interviews, no clinical diagnoses were able to be confirmed, 68%, 53%, and 26% of respondents reported symptom levels associated with high risk for depression, anxiety disorders, and posttraumatic stress disorder (PTSD), respectively. Between one quarter and one half of respondents reported symptom levels associated with high risk regarding measured dimensions of burnout. Female workers reported significantly more symptoms of anxiety, depression, PTSD, and emotional exhaustion than males. Workers with the United Nations and related agencies reported fewest symptoms. Higher levels of social support, stronger team cohesion, and reduced exposure to chronic stressors were associated with improved mental health. National humanitarian staff members in Gulu have high exposure to chronic and traumatic stress and high risk of a range of poor mental health outcomes. Given that work‐related factors appear to influence the relationship between the two strategies are suggested to support the well‐being of national staff working in such contexts.
Hepatocyte nuclear factor 1β is a novel prognostic marker independent of the milan criteria in transplantable hepatocellular carcinoma: A retrospective analysis based on tissue microarrays
Authors: Shim Ju Hyun , Lee Han Chu , Han Seungbong , Kang Hyo Jeong , Yu Eunsil , Lee Sung-Gyu
Published: December 2012

We retrospectively investigated the prognostic value of hepatocyte nuclear factor 1 (HNF1) proteins in 159 liver transplant patients with hepatocellular carcinoma (HCC), including 36 (22.6%) exceeding the Milan criteria. The expression of alpha-fetoprotein (AFP), HNF1α, and HNF1β was examined with immunohistochemistry on duplicate tissue microarray slides containing HCC tumor explants. The times to recurrence and cancer death were analyzed with a Cox regression model and were compared according to the expression of markers of interest. We compared risk predictions with area under the receiver operator curves (AUROCs) and C statistics. AFP, HNF1α, and HNF1β were positive in 22.6%, 46.5%, and 61.0% of the tumor immunoprofiles, respectively. Although several variables were associated with the times to recurrence and cancer death in univariate Cox analyses, only AFP expression for the time to recurrence and the Milan criteria and HNF1β expression for the times to recurrence and cancer death remained significant after multivariate adjustments. The expression of HNF1β (but not HNF1α) was related to a serum AFP level ≥ 200 ng/mL, microvascular invasion, and AFP expression (P < 0.05 for all). A subgroup analysis showed that in the group meeting the Milan criteria, recurrence and cancer death rates at 10 years in the HNF1β-negative patients were approximately one-tenth of those in the HNF1β-positive patients, but the difference was not significant in the group exceeding the Milan criteria. The addition of HNF1β expression to the Milan criteria increased the C statistics and AUROCs for both recurrence and mortality (P < 0.05 for all). In conclusion, the immunohistological detection of HNF1β predicts recurrence and HCC-specific death after transplantation and provides an additive benefit in comparison with the Milan selection criteria on their own.
Reactive Extrusion of Stereocomplexed Poly‐L,D‐lactides: Processing, Characterization, and Properties
Authors: Gallos Antoine , Fontaine Gaëlle , Bourbigot Serge
Published: December 2012

This work reports a facile route to synthesize homochiral and stereocomplexed polylactide by reactive extrusion. The effect of the polymerization catalyst (combination of tin(II)octanoate and triphenylphosphine) before and after its deactivation is discussed. Poly‐L‐lactide (PLLA) exhibits homochiral crystallinity and diblock poly‐L,D‐lactide (PDLLA) exhibits stereocomplex crystallinity. The presence of residual monomer leads to a plasticizing effect, reducing glass transition temperature (Tg). Changes of the tacticity (L,D‐tacticity) of the stereocomplex are due to the transesterification reactions between L and D units. Deactivation of the catalyst reduces transesterification reactions and preserves the polylactide stereocomplex upon heating.

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Role of Gender in Conflict Handling in the Context of Outsourcing Service Marketing
Authors: Ndubisi Nelson Oly
Published: December 2012

Do male and female outsourcing service marketers differ in their responses to conflict‐handling styles of outsourcers? The paper addresses this question by identifying relationship‐oriented typologies of conflict handling from extant literature and examining their effects on key relational outcomes in outsourcing relationship in Asia. Specifically, the paper considers how outsourcers’ conflict‐handling styles impact trust and commitment by male and female outsourcing service providers’ (OSPs). Data were collected from male and female OSPs and analyzed using Factor and Hierarchical Multiple Regression analyses. Findings show significant differences in the relationship between conflict‐handling styles and relational outcomes between male and female OSPs. Precisely, integrating conflict handling–trust relationship is significantly stronger for males than for females, whereas compromising conflict handling–trust relationship is significantly stronger for females than for males. Findings show no statistical differences in accommodating conflict handling–trust relationship between the groups. These findings lead to research and managerial implications that conclude the paper.
Organ specificity of beta‐carotene induced lung gene‐expression changes in Bcmo1−/− mice
Authors: van Helden Yvonne G. J. , Godschalk Roger W. L. , van Schooten Frederik J. , Keijer Jaap
Published: December 2012

Scope

Whole genome transcriptome analysis of male and female beta‐carotene 15,15′‐monooxygenase knockout (Bcmo1−/−) and Bcmo1+/+ (wild‐type) mice with or without 14 wk of BC supplementation was done. We previously showed that only 1.8% of the genes regulated by BC in lung were also regulated in liver and inguinal white adipose tissue (iWAT), suggesting lung specific responses. Here, we explicitly questioned the lung specificity.

Methods and results

We show that BC supplementation resulted in an opposite direction of gene‐regulation in male compared to female Bcmo1−/− mice in lung, liver, and iWAT. This supports a systemic effect of BC on steroid hormone metabolism mediated responses. Lung, liver, and iWAT of female Bcmo1−/− mice showed an increased inflammatory response, which was counteracted by supplementation of BC. This supports a genotype dependent increased sensitivity of female mice for vitamin A deficiency. Finally, the effect of BC on Wnt signaling in male Bcmo1−/− mice was examined. Frizzled homolog 6 (Fzd6) downregulation was seen in all three tissues. Collagen triple helix containing 1 (Cthrc1) downregulation was seen in lung tissue only, suggesting specificity. Upregulation of genes involved in oxygen sensing was seen in lung and iWAT, while protocadherin upregulation was only seen in lung.

Conclusion

Our results demonstrate that effects of BC are strongly sex dependent. While effects of BC on hormone metabolism mediated responses and inflammation are systemic, effects on Wnt signaling may be lung specific.
Assessing breast cancer angiogenesis in vivo: which susceptibility contrast MRI biomarkers are relevant?
Authors: Kim Eugene , Cebulla Jana , Ward B. Douglas , Rhie Kevin , Zhang Jiangyang , Pathak Arvind P.
Published: December 2012

Purpose

There is an impending need for noninvasive biomarkers of breast cancer angiogenesis to evaluate the efficacy of new anti‐angiogenic therapies in vivo. The purpose of this study was to systematically evaluate the sensitivity of in vivo steady‐state susceptibility contrast‐MRI biomarkers of angiogenesis in a human breast cancer model.

Methods

Orthotopic MDA‐MB‐231 human breast cancer xenografts were imaged by steady‐state susceptibility contrast‐MRI at post‐inoculation week 3 and post‐inoculation week 5, followed by ex vivo whole tumor 3D micro‐CT angiography. “Absolute” (i.e., measures of vascular morphology in appropriate units) and “relative” (i.e., proportional to measures of vascular morphology) MRI biomarkers of tumor blood volume, vessel size, and vessel density were computed and their ability to predict the corresponding micro‐CT analogs assessed using cross‐validation analysis.

Results

All MRI biomarkers significantly correlated with their micro‐CT analogs and were sensitive to the micro‐CT‐measured decreases in tumor blood volume and vessel density from post‐inoculation week 3 to post‐inoculation week 5. However, cross‐validation analysis revealed there was no significant difference between the predictive accuracy of “absolute” and “relative” biomarkers.

Conclusion

As “relative” biomarkers are more easily computed from steady‐state susceptibility contrast‐MRI (i.e., without additional MRI measurements) than “absolute” biomarkers, it makes them promising candidates for assessing breast cancer angiogenesis in vivo. Magn Reson Med, 70:1106–1116, 2013. © 2012 Wiley Periodicals, Inc.
Meso‐scale particle modeling of concrete deterioration caused by alkali‐aggregate reaction
Authors: Pan Jianwen , Feng Y. T. , Jin Feng , Xu Yanjie , Sun Qicheng , Zhang Chuhan , Owen D. R. J.
Published: December 2012

A meso‐scale particle model is presented to simulate the expansion of concrete subjected to alkali‐aggregate reaction (AAR) and to analyze the AAR‐induced degradation of the mechanical properties. It is the first attempt to evaluate the deterioration mechanism due to AAR using the discrete‐element method. A three‐phase meso‐scale model for concrete composed of aggregates, mortar and the interface is established with the combination of a pre‐processing approach and the particle flow code, PFC2D. A homogeneous aggregate expansion approach is applied to model the AAR expansion. Uniaxial compression tests are conducted for the AAR‐affected concrete to examine the effects on the mechanical properties. Two specimens with different aggregate sizes are analyzed to consider the effects of aggregate size on AAR. The results show that the meso‐scale particle model is valid to predict the expansion and the internal micro‐cracking patterns caused by AAR. The two different specimens exhibit similar behavior. The Young's modulus and compressive strength are significantly reduced with the increase of AAR expansion. The shape of the stress–strain curves obtained from the compression tests clearly reflects the influence of internal micro‐cracks: an increased nonlinearity before the peak loading and a more gradual softening for more severely affected specimens. Similar macroscopic failure patterns of the specimens under compression are observed in terms of diagonal macroscopic cracks splitting the specimen into several triangular pieces, whereas localized micro‐cracks forming in slightly affected specimens are different from branching and diffusing cracks in severely affected ones, demonstrating different failure mechanisms. Copyright © 2012 John Wiley & Sons, Ltd.
Polysulfone/Brij‐58 blend nanofiltration membranes: preparation, morphology and performance
Authors: Saljoughi E. , Mousavi S. M. , Hosseini S. A.
Published: December 2012

In present research, novel asymmetric polysulfone (PSF) membranes with high hydrophilicity and noticeable rejection of arsenic, as one of the major environmental problems, were prepared from PSF/Brij‐58/NMP (1‐methyl‐2‐pyrrolidone) system via immersion precipitation. Pure water was used as gelation media. The variation effect of coagulation bath temperature (CBT) and addition of Brij‐58 on morphology, wettabiliy, pure water permeation flux and rejection of As (III) and As (V), as two dominant states of arsenic in the nature, were studied by scanning electron microscopy, contact angle measuring instrument and experimental setup. The results demonstrated that both hydrophilicity and rejection properties of the prepared membranes were significantly enhanced by small addition of Brij‐58 surfactant in the casting solution along with using the lowest level of CBT. Addition of 4 wt. % of Brij‐58 and using cold coagulation bath resulted in the highest rejection of As (V). Initial increase in Brij‐58 concentration, from 0 wt. % to 2 wt. %, resulted in higher rejection of As (III). However, higher Brij‐58 concentrations than 2 wt. % (increase from 2 wt. % to 6 wt. %) led to lower rejection of As (III). Also, it was found out that addition of Brij‐58 in the casting solution along with increasing the CBT resulted in formation of membranes with high permeability and sub‐layer porosity and thin top layer. Copyright © 2012 John Wiley & Sons, Ltd.
Morphology and properties of the biosourced poly(lactic acid)/poly(ethylene oxide‐b‐amide‐12) blends
Authors: Han Lijing , Han Changyu , Dong Lisong
Published: December 2012

Biosourced poly(lactic acid) (PLA) blends with different content of poly(ethylene oxide‐b‐amide‐12) (PEBA) were prepared by melt compounding. The miscibility, phase structure, crystallization behavior, mechanical properties, and toughening mechanism were investigated. The blend was an immiscible system with the PEBA domains evenly dispersed in the PLA matrix. The PEBA component suppressed the nonisothermal melt crystallization of PLA. With the addition of PEBA, marked improvement in toughness of PLA was achieved. The maximum for elongation at break and impact strength of the blend reached the level of 346% and 60.5 kJ/m2, respectively. The phase morphology evolution in the PLA/PEBA blends after tensile and impact tests was investigated, and the corresponding toughening mechanism was discussed. It was found that the PLA matrix demonstrates obvious shear yielding in the blend during the tensile and impact tests, which induced energy dissipation and therefore lead to improvement in toughness of the PLA/PEBA blends. POLYM. COMPOS., 2013. © 2012 Society of Plastics Engineers
Statins in the prevention of dementia and Alzheimer's disease: A meta‐analysis of observational studies and an assessment of confounding
Authors: Wong William B. , Lin Vincent W. , Boudreau Denise , Devine Emily Beth
Published: December 2012

Background

Studies demonstrate the potential for statins to prevent dementia and Alzheimer's disease (AD), but the evidence is inconclusive.

Objective

Conduct a meta‐analysis to estimate any benefit of statins in preventing dementia and examine the potential effect of study design and confounding on the benefit of statins in dementia. A secondary goal is to explore factors that may elucidate the mechanisms by which statins exert their potentially beneficial effect.

Methods

Performed systematic literature review to identify relevant publications. Relative risk (RR) estimates were pooled using both fixed and random effect models. Studies were stratified by study design and potential confounding factors.

Results

The pooled results for all‐type dementia suggest that use of statins is associated with a lower RR of dementia when compared to non‐statin users (random effects model: RR 0.82 (95%CI [0.69, 0.97]). The pooled results for AD also suggested a lower RR with statin user compared to non‐statin users in random effects models (RR: 0.70, 95% CI [0.60, 0.83]). Study design and methods used to address biases may influence the results.

Conclusion

These pooled results suggest that statins may provide a slight benefit in the prevention of AD and all‐type dementia. This benefit observed in both disease states should be interpreted with caution as observational studies are subject to bias, and it is possible that the slight benefit observed may disappear when these biases are addressed in a well‐designed randomized controlled trial. Copyright © 2012 John Wiley & Sons, Ltd.
THE ROLE OF PEER ATTACHMENT AND NORMATIVE BELIEFS ABOUT AGGRESSION ON TRADITIONAL BULLYING AND CYBERBULLYING
Authors: Burton K. Alex , Florell Dan , Wygant Dustin B.
Published: December 2012

This study examined the effects of normative beliefs about aggression and peer attachment on traditional bullying, cyberbullying, and both types of victimization. Cyberbullying departs from traditional forms of bullying in that it is through forms of technology, such as the Internet, which increases situational anonymity. Eight hundred fifty students in Grades 6 through 8 completed a survey that assessed normative beliefs about aggression, peer attachment, and traditional bullying and cyberbullying behaviors, which suggested that students who are involved with traditional bullying are also involved in cyberbullying. Adolescents with higher normative beliefs about aggression are more likely to be traditional bullies, traditional victims, cyberbullies, and cybervictims. Additionally, peer attachment was found to be negatively associated with both types of bullying and victimization. Implications and future directions are discussed.
Stability results for random discrete structures
Authors: Samotij Wojciech
Published: December 2012

Two years ago, Conlon and Gowers, and Schacht proved general theorems that allow one to transfer a large class of extremal combinatorial results from the deterministic to the probabilistic setting. Even though the two papers solve the same set of long‐standing open problems in probabilistic combinatorics, the methods used in them vary significantly and therefore yield results that are not comparable in certain aspects. In particular, the theorem of Schacht yields stronger probability estimates, whereas the one of Conlon and Gowers also implies random versions of some structural statements such as the famous stability theorem of Erdős and Simonovits. In this paper, we bridge the gap between these two transference theorems. Building on the approach of Schacht, we prove a general theorem that allows one to transfer deterministic stability results to the probabilistic setting. We then use this theorem to derive several new results, among them a random version of the Erdős‐Simonovits stability theorem for arbitrary graphs, extending the result of Conlon and Gowers, who proved such a statement for so‐called strictly 2‐balanced graphs. The main new idea, a refined approach to multiple exposure when considering subsets of binomial random sets, may be of independent interest.Copyright © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 44, 269‐289, 2014
Notch signaling in the pancreas: patterning and cell fate specification
Authors: Afelik Solomon , Jensen Jan
Published: December 2012

Notch signaling is an evolutionarily conserved mechanism adapted to control binary fate decisions. The first evidence of Notch in pancreatic development focused on its critical role in controlling endocrine fate decisions. Since then, we have come to understand that this signaling system operates iteratively in the pancreas, and is not limited to the control of endocrine fate decision. Notch appears to play a role in early organ development, then during organ domain patterning, and only during a final refinement process, in the control of terminal cell fates. In so doing, Notch receptors and their ligands are under the influence of a wealth of genetic components that together help orchestrate the building of a complex, glandular organ. WIREs Dev Biol 2012, 2:531–544. doi: 10.1002/wdev.99

This article is categorized under:

Establishment of Spatial and Temporal Patterns > Repeating Patterns and Lateral Inhibition
An introduction to Hesiod's Works and Days
Authors: Bartlett Robert C.
Published: December 2012

The present essay sketches the outline and the intention of Hesiod's Works and Days. Hesiod's principal task appears to be the identification (and praise) of the best way of life for his wayward brother Perses, but in carrying out this task, Hesiod speaks of justice and its human and divine supports in such a way as to go well beyond what would be of benefit to his brother. For in the course of his analysis of justice, or as a result of it, Hesiod praises also the life of autonomous understanding, the life that appears to be the poet's own. In crucial ways, then, Hesiod explores the chief themes of what was to become political philosophy, and for this reason, among others, he deserves the attention of all those who are also concerned with it.
Defining the epidemiology of bloodstream infections: the ‘gold standard’ of population-based assessment
Authors: LAUPLAND K. B.
Published: December 2012

Bloodstream infections (BSIs) are a major cause of morbidity and mortality. Although population-based studies have been proposed as an optimal means to define their epidemiology, the merit of these designs has not been well documented. This report investigated the potential value of using population-based designs in defining the epidemiology of BSIs. Population-based BSI surveillance was conducted in Calgary, Canada (population 1·24 million) and illustrative comparisons were made between the overall and selected subgroup cohorts within five main themes. The value of population denominator data, and age and gender standardization for calculation and comparison of incidence rates were demonstrated. In addition, a number of biases including those related to differential admission rates, selected hospital admission, and referral bias were highlighted in non-population-based cohorts. Due to their comprehensive nature and intrinsic minimization of bias, population-based designs should be considered the gold standard means of defining the epidemiology of an infectious disease.
Microbial enhancement of seed germination in Rosa corymbifera ‘Laxa’
Authors: Morpeth David R. , Hall Avice M.
Published: December 2012

Germination of native tree and shrub species from seed can be unpredictable. Germination of Rosa corymbifera ‘Laxa’ was 2% under normal commercial conditions. This was obtained in the presence of the natural microflora found on the seeds. The microflora originated on the hips and the seeds become inoculated during extraction. Exclusion of microbes from such pretreatments resulted in no germination. Inoculation of surface sterilized seeds with members of the natural microflora resulted in 3% germination. The addition of GarottaTM, a commercial compost activator, to the commercial pretreatment increased germination to 95%. This high germination percentage was sustained over a 5 year period using seeds from the same stock bushes. Addition of the compost activator resulted in a 20-fold increase of microbial activity in the pretreatment mixture, indicating that enhanced microbial growth resulted in higher and more predictable germination percentages.
Late Eocene North American microtektites and clinopyroxene‐bearing spherules
Authors: Glass B. P. , Burns Christopher A. , Crosbie Jill R. , DuBois David L.
Published: December 2012

Approximately 35 m.y. ago two events, separated by only 10,000–20,000 years, each spread roughly 1 billion metric tons of silicate spherules over large areas of the Earth's surface. The older event produced mostly clinopyroxene‐bearing spherules (cpx spherules). The cpx spherules have been found in the Caribbean Sea, Gulf of Mexico, equatorial Pacific, and eastern equatorial Indian Ocean. The cpx spherule layer is associated with an iridium anomaly and appears to coincide with the extinction of several species of Radiolaria. The composition and widespread distribution of the cpx spherules indicate that they were formed by an impact event. The younger layer of spherules consists of microtektites belonging to the North American tektite strewn field based on age and elemental and isotopic composition. The North American microtektites have been found in the western equatorial Atlantic, on Barbados, in the Caribbean Sea, and in the Gulf of Mexico. The North American microtektite layer is not synchronous with an iridium anomaly, nor does it appear to be associated with any major changes in the microfossils. Neither the cpx spherule event nor the North American tektite event appears to be associated with a climatic change, but no detailed studies have been made across either layer. Excluding the cpx layer, which contains mostly crystal‐bearing spherules, the evidence at the present time indicates that there is only one late Eocene microtektite layer and it is part of the North American strewn field.
Xenolith digestion in large magma bodies
Authors: Walker David , Kiefer Walter S.
Published: December 2012

Xenolith digestion during sinking in a corrosive magma is treated with a surface‐controlled dissolution relation suggested from recent experiments on silicate crystals. The relation is shown to apply to a wide range of dynamical regimes from analog experiments on NaCl dissolution in water. Using this relation, xenolith penetration by sinking into magmas is shown to be strongly dependent on xenolith size. Crystal sinking is unimportant but sinking of meter‐sized chunks can be a major process of mass and heat transport in planetary‐scale magma body evolution. This evolution cannot be adequately treated with current information.
The diogenite‐eucrite links and the crystallization history of a crust of their parent body
Authors: Takeda Hiroshi , Mori Hiroshi
Published: December 2012

Aspects of the crystallization history of the primitive crust of the HED (howardites, eucrites, diogenites) achondrite parent body have been deciphered from the microtextures and chemical compositions of pyroxene and plagioclase in some Antarctic HED achondrites intermediate to diogenite and eucrite. Five new specimens related to Yamato 75032 and three eucritic clasts in Y791186 and Y791208 have been investigated by electron microprobe, analytical transmission electron microscope, and X ray diffraction techniques. Their pyroxene compositions cover the entire range from Fe‐rich diogenite to eucrite. The pyroxene textures of the Y75032‐type achondrites indicate that many of them crystallized as low‐Ca pigeonite, and some as orthopyroxene. Later shock events modified the original inversion and exsolution textures. The chemical compositions and the interstitial occurrence of plagioclase crystals in pyroxene indicate crystallization from intercumulus trapped liquid. The pyroxene crystallization and the relation between the anorthite content (An) of plagioclase and the Mg/(Mg + Fe) number of the coexisting pyroxene in these specimens reveal two crystallization trends: One trend is intermediate to that of the Mg‐rich suites of the lunar highland crust and that of ferroan anorthosite, and the other is a trend with a steep decrease in the An content, while the Mg/(Mg + Fe) of the pyroxene remains effectively constant. A model involving crystal fractionation in a shallow magma ocean or intrusion in the parent body has been proposed.
A Monte Carlo study of parameters affecting computer simulations of crater saturation density
Authors: Woronow Alex
Published: December 2012

Computer models of cratered surfaces often use inputs of uncertain nature and importance. This work evaluates the sensitivity of the resulting crater‐saturation estimates to the input parameters, principally applicable to the study of craters upward from 8 km diameter. In order of decreasing importance, crater saturation simulations are found to be sensitive to (1) the dynamic range of crater diameters used, (2) the effectiveness of ejecta‐blanket obliteration assumed, and (3) the number of points taken to describe the crater rim. The size of the largest crater in proportion to the size of the simulated surface has no effect on the results when the edges of the simulated surface are correctly treated and craters are not counted simply by integers. Craters should be counted by their fractions lying within the simulated area. A similar procedure is recommended when gathering crater size‐density data from images.
Prevalent Glucocorticoid and Androgen Activity in US Water Sources
Authors: Stavreva Diana A. , George Anuja A. , Klausmeyer Paul , Varticovski Lyuba , Sack Daniel , Voss Ty C. , Schiltz R. Louis , Blazer Vicki S. , Iwanowicz Luke R. , Hager Gordon L.
Published: December 2012

Contamination of the environment with endocrine disrupting chemicals (EDCs) is a major health concern. The presence of estrogenic compounds in water and their deleterious effect are well documented. However, detection and monitoring of other classes of EDCs is limited. Here we utilize a high-throughput live cell assay based on sub-cellular relocalization of GFP-tagged glucocorticoid and androgen receptors (GFP-GR and GFP-AR), in combination with gene transcription analysis, to screen for glucocorticoid and androgen activity in water samples. We report previously unrecognized glucocorticoid activity in 27% and androgen activity in 35% of tested water sources from 14 states in the US. Steroids of both classes impact body development, metabolism and interfere with reproductive, endocrine and immune systems. This prevalent contamination could negatively affect wildlife and human populations.
Subarachnoid Hemorrhage from a Thoracic Radicular Artery Pseudoaneurysm after Methamphetamine and Synthetic Cannabinoid Abuse: Case Report
Authors: Ray Wilson Z. , Krisht Khaled M. , Schabel Alex , Schmidt Richard H.
Published: December 2012

Background Context

Isolated spinal artery aneurysms not associated with vascular malformations are exceedingly rare.

Purpose

To present a rare case of subarachnoid hemorrhage after thoracic radiculomedullary artery pseudoaneurysm rupture in a patient who abused synthetic cannabinoids and methamphetamines.

Study Design

Case report.

Methods

A 41-year-old man with a history of polysubstance abuse presented with acute-onset headache, back pain, and transient bilateral lower-extremity numbness. He reported daily use of the synthetic cannabinoid “Spice.” He denied use of other illegal drugs, but laboratory testing was positive for methamphetamines. Magnetic resonance imaging showed a focal hematoma at T2–3, and spinal angiography was negative for vascular abnormalities; however, a follow-up angiogram 6 days later revealed interval development of an irregular dilation of the left T3 radiculomedullary artery originating from the left supreme intercostal artery.

Results

Surgical trapping and resection of the lesion yielded a good clinical outcome.

Conclusions

Although two previous case reports have described patients with thoracic radiculomedullary pseudoaneurysm causing spinal subarachnoid hemorrhage (SAH), this is the first reported case associated with synthetic cannabinoids and methamphetamine abuse. Although this diagnosis is exceptionally rare, clinical presentation of SAH with associated back pain and lower-extremity symptoms warrants an aggressive imaging workup. Even in the setting of negative angiography, repeat cerebral and spinal angiograms may be necessary to identify a potentially treatable cause of spinal SAH.
High selective two-dimensional Bragg resonators of planar geometry: Theoretical, computational, and experimental study
Authors: Ginzburg N. S. , Peskov N. Yu. , Sergeev A. S. , Zaslavsky V. Yu. , Arzhannikov A. V. , Kalinin P. V. , Sinitsky S. L. , Thumm M.
Published: December 2012

Electrodynamic properties of two-dimensional (2D) planar Bragg resonators realising 2D distributed feedback were studied. It is shown that high selectivity of a 2D Bragg resonator originates from the specificity of the dispersion diagrams of normal waves in a double-periodic corrugated unbounded planar waveguide resulting in formation of high-Q eigenmodes in the vicinity of the Bragg resonance frequency. Results of theoretical analysis in the frame of geometric-optical approach of coupled-wave theory coincide well with 3D simulations using the code CST “Microwave Studio” and are corroborated by data obtained in “cold” microwave tests. Frequency dependences of scattering coefficients were measured for incident wave-beams of different structures and excitation of the high-Q eigenmodes has been demonstrated.
Energy harvesting from a convection-driven Rijke-Zhao thermoacoustic engine
Authors: Zhao Dan , Chew Y.
Published: December 2012

A convection-driven Rijke-Zhao thermoacoustic engine is developed. It can produce intensive oscillations at two different temperatures. Furthermore, it does not involve any heat exchanger and stack/regenerator, which play critical roles in conduction-driven standing- or travelling-wave engines. Thus, the Rijke-Zhao engine is much simpler in design and lower cost in fabrication. To demonstrate its potential of energy-harvesting, a design for the conversion of heat into electricity via sound is proposed by integrating Rijke-Zhao engine with a piezoelectric generator. The preliminary experimental results are presented. And it is found that 60% more power is generated than that from conduction-driven standing-wave thermoacoustic-piezoelectric resonator [Smoker et al., J. Appl. Phys. 111, 104901, (2012)]. In order to gain insights on the generation mechanism of the thermoacoustic oscillations in the present energy-harvesting system, 2D numerical simulations are conducted. Comparing the numerical results with the experimental one reveals that good quantitative agreement is obtained.
The impact of the stress induced by lateral spatial hole burning on the degradation of broad-area AlGaAs/GaAs laser diodes
Authors: Qiao Yanbin , Feng Shiwei , Xiong Cong , Ma Xiaoyu , Zhu Hui , Guo Chunsheng , Wei Guanghua
Published: December 2012

The degradation of broad-area AlGaAs/GaAs laser diodes is studied experimentally and theoretically in detail, and we suggest a degradation mechanism associated with the stress which originates from the lateral spatial hole burning (SHB) effects. Our analysis shows that thermal stresses have critical effects on the degradation of laser diodes, which are induced by increased local heating by nonradiative recombination and self-absorption of photons originating from the lateral SHB within the laser diode during degradation. Such results are confirmed by the simulation using the software lastip. Furthermore, the average values of the induced thermal strain and stress by lateral SHB are 0.00063 and 85 MPa, respectively, through the x-ray diffraction measurement. The stress exceeds that for the initiation of plastic deformation (as calculated to be approximately 40–50 MPa based on the finite element method), thus, suggesting that plastic deformation has occurred within the cavity due to the lateral SHB effect during degradation of laser diodes.
Thin-film silicon triple-junction solar cell with 12.5% stable efficiency on innovative flat light-scattering substrate
Authors: Söderström Karin , Bugnon Grégory , Biron Rémi , Pahud Céline , Meillaud Fanny , Haug Franz-Josef , Ballif Christophe
Published: December 2012

Several thin-film solar cell technologies require light-trapping schemes that are predominantly based on depositing the solar cells on rough surfaces. While this approach efficiently increases the density of photo-generated carriers, open-circuit voltage and fill factor generally decrease. Substrates that decouple the growth interface from the light-scattering interface were previously proposed as a solution to this dilemma, and proof-of-concepts were demonstrated in thin film-silicon solar cells. In this contribution, we review as an introduction the problematic of rough versus smooth interface for n-i-p single-junction μc-Si:H cells. Then, the benefits of the newly developed substrate that decouples the growth and scattering interfaces are investigated in n-i-p triple-junction a-Si:H/μc-Si:H/μc-Si:H solar cells for the first time. Conversion efficiencies of 13.7% (initial) and 12.5% (stabilized) are obtained, which are among the highest ever reported for such devices.
Polarization pyrometry: An improvement to multi-wavelength optical pyrometry
Authors: Ni P. A. , More R. M. , Yoneda H. , Bieniosek F. M.
Published: December 2012

We describe a new method that improves upon temperature measurement by optical pyrometry. The main uncertainty in the traditional pyrometry technique is the surface emissivity, which is generally unknown and hard to measure. A common approach to deal with this problem is to measure the thermal emission at multiple wavelengths – an approach called multi-wavelength pyrometry. However, this technique can still result in a level of uncertainty in the surface temperature that is unsatisfactory for scientific applications, such as a measurement of equation of state of warm dense matter. In contrast to the conventional multi-wavelength technique, in the polarization pyrometry approach described herein, p- and s-polarization components of thermal radiation at multiple-angles are used to deduce the temperature. This paper describes the concept and the results of an initial proof-of-principle static experiment with an electrically heated tungsten ribbon. It was found that in the same experiment, the accuracy of the polarization pyrometry measurement was substantially greater than that achieved using conventional multi-wavelength pyrometry.
Orientation-selective X-ray dark field imaging of ordered systems
Authors: Revol V. , Kottler C. , Kaufmann R. , Neels A. , Dommann A.
Published: December 2012

X-ray scatter dark field imaging with a grating interferometer is becoming a standard tool for the characterization of microscopic texture of samples. Recently, it was shown that directional information could also be recovered when the sample displays an anisotropic ordering such as, for instance, a bundle of microscopic fibers. Here, we demonstrate that previously suggested approaches are ambiguous when multiple anisotropic orientations coexist in the sample. Therefore, we developed a new orientation-selective approach which allows for separating the contributions of individual orientations provided that these orientations are known a-priori. The method, demonstrated experimentally using a well-defined wood sample, is envisioned to be of high interest for the non-destructive inspection of composite materials.
Embedded Gaussian unitary ensembles with U(Ω)⊗SU(r) embedding generated by random two-body interactions with SU(r) symmetry
Authors: Vyas Manan , Kota V. K. B.
Published: December 2012

Following the earlier studies on embedded unitary ensembles generated by random two-body interactions [EGUE(2)] with spin SU(2) and spin-isospin SU(4) symmetries, developed is a general formulation, for deriving lower order moments of the one- and two-point correlation functions in eigenvalues, that is valid for any EGUE(2) and BEGUE(2) (“B” stands for bosons) with U(Ω)⊗SU(r) embedding and with two-body interactions preserving SU(r) symmetry. Using this formulation with r = 1, we recover the results derived by Asaga et al. [Ann. Phys. (N.Y.) 297, 344 (2002)]10.1006/aphy.2002.6248 for spinless boson systems. Going further, new results are obtained for r = 2 (this corresponds to two species boson systems) and r = 3 (this corresponds to spin 1 boson systems).
Molecular dynamics simulations of a new branched antimicrobial peptide: A comparison of force fields
Authors: Li Jianguo , Lakshminarayanan Rajamani , Bai Yang , Liu Shouping , Zhou Lei , Pervushin Konstantin , Verma Chandra , Beuerman Roger W.
Published: December 2012

Branched antimicrobial peptides are promising as a new class of antibiotics displaying high activity and low toxicity and appear to work through a unique mechanism of action. We explore the structural dynamics of a covalently branched 18 amino acid peptide (referred to as B2088) in aqueous and membrane mimicking environments through molecular dynamics (MD) simulations. Towards this, we carry out conventional MD simulations and supplement these with replica exchange simulations. The simulations are carried out using four different force fields that are commonly employed for simulating biomolecular systems. These force fields are GROMOS53a6, CHARMM27 with cMAP, CHARMM27 without cMAP and AMBER99sb. The force fields are benchmarked against experimental data available from circular dichroism and nuclear magnetic resonance spectroscopies, and show that CHARMM27 without cMAP correction is the most successful in reproducing the structural dynamics of B2088 both in water and in the presence of micelles. Although the four force fields predict different structures of B2088, they all show that B2088 stabilizes against the head group of the lipid through hydrogen bonding of its Lys and Arg side chains. This leads us to hypothesize that B2088 is unlikely to penetrate into the hydrophobic region of the membrane owing to the high free energy costs of transfer from water, and possibly acts by carpeting and thus disrupting the membrane.
Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range
Authors: Toussaint Julia , Grüner Roman , Schubert Marco , May Torsten , Meyer Hans-Georg , Dietzek Benjamin , Popp Jürgen , Hofherr Matthias , Arndt Matthias , Henrich Dagmar , Il'in Konstantin , Siegel Michael
Published: December 2012

We have developed a cryogenic measurement system for single-photon counting, which can be used in optical experiments requiring high time resolution in the picosecond range. The system utilizes niobium nitride superconducting nanowire single-photon detectors which are integrated in a time-correlated single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical design, the electrical setup, and the cryogenic optical components. The performance of the complete system in TCSPC mode is tentatively benchmarked using 140 fs long laser pulses at a repetition frequency of 75 MHz. Due to the high temporal stability of these pulses, the measured time resolution of 35 ps (FWHM) is limited by the timing jitter of the measurement system. The result was cross-checked in a Coherent Anti-stokes Raman Scattering (CARS) setup, where scattered pulses from a β-barium borate crystal have been detected with the same time resolution.