bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice cluster theory for polymer melts with specific interactions
Authors: Xu Wen-Sheng , Freed Karl F.
Published: July 2014

Despite the long-recognized fact that chemical structure and specific interactions greatly influence the thermodynamic properties of polymer systems, a predictive molecular theory that enables systematically addressing the role of chemical structure and specific interactions has been slow to develop even for polymer melts. While the lattice cluster theory (LCT) provides a powerful vehicle for understanding the influence of various molecular factors, such as monomer structure, on the thermodynamic properties of polymer melts and blends, the application of the LCT has heretofore been limited to the use of the simplest polymer model in which all united atom groups within the monomers of a species interact with a common monomer averaged van der Waals energy. Thus, the description of a compressible polymer melt involves a single van der Waals energy. As a first step towards developing more realistic descriptions to aid in the analysis of experimental data and the design of new materials, the LCT is extended here to treat models of polymer melts in which the backbone and side groups have different interaction strengths, so three energy parameters are present, namely, backbone-backbone, side group-side group, and backbone-side group interaction energies. Because of the great algebraic complexity of this extension, we retain maximal simplicity within this class of models by further specializing this initial study to models of polymer melts comprising chains with poly(n-α-olefin) structures where only the end segments on the side chains may have different, specific van der Waals interaction energies with the other united atom groups. An analytical expression for the LCT Helmholtz free energy is derived for the new model. Illustrative calculations are presented to demonstrate the degree to which the thermodynamic properties of polymer melts can be controlled by specific interactions.
Specific features of the temperature behavior of the ESR spectra of Fe-doped mercury selenide
Authors: Lamonova K. , Bekirov B. , Ivanchenko I. , Popenko N. , Zhitlukhina E. , Burkhovetskii V. , Orel S. , Pashkevich Yu.
Published: July 2014

The ESR study of a dilute magnetic semiconductor HgSe:Fe with the iron concentration 2 × 1018 cm−3 < NFe < 3 × 1019 cm–3 was carried out in the temperature range 77 K < T < 300 K. As was shown by microstructure analysis, the iron ions are distributed uniformly in the bulk of HgSe:Fe samples and do not form a crystal structure different from that of zinc blende in their vicinity. Based on the g-factor calculations it was concluded that Fe3+ ions in the tetrahedral sites of HgSe samples are the source of the ESR signal; the shape of the ESR spectra is determined by the combined effect of the Jahn-Teller distortions of the tetrahedral environment and the displacements of an iron ion from the center of the tetrahedron; the evolution of the ESR spectra with increasing the iron concentration can be explained within the model of the regular lattice of charged donors. The temperature at which the regular lattice of impurity ions is formed was determined by the maximum on the temperature dependence of the ESR linewidth for the samples with different iron concentrations.
Design and characterization of a 32-channel heterodyne radiometer for electron cyclotron emission measurements on experimental advanced superconducting tokamak
Authors: Han X. , Liu X. , Liu Y. , Domier C. W. , Luhmann N. C. , Li E. Z. , Hu L. Q. , Gao X.
Published: July 2014

A 32-channel heterodyne radiometer has been developed for the measurement of electron cyclotron emission (ECE) on the experimental advanced superconducting tokamak (EAST). This system collects X-mode ECE radiation spanning a frequency range of 104–168 GHz, where the frequency coverage corresponds to a full radial coverage for the case with a toroidal magnetic field of 2.3 T. The frequency range is equally spaced every 2 GHz from 105.1 to 167.1 GHz with an RF bandwidth of ∼500 MHz and the video bandwidth can be switched among 50, 100, 200, and 400 kHz. Design objectives and characterization of the system are presented in this paper. Preliminary results for plasma operation are also presented.
Application of lateral photovoltage towards contactless light beam induced current measurements and its dependence on the finite beam size
Authors: Abhale Atul Prakash , Rao K. S. R. Koteswara
Published: July 2014

The nature of the signal due to light beam induced current (LBIC) at the remote contacts is verified as a lateral photovoltage for non-uniformly illuminated planar p-n junction devices; simulation and experimental results are presented. The limitations imposed by the ohmic contacts are successfully overcome by the introduction of capacitively coupled remote contacts, which yield similar results without any significant loss in the estimated material and device parameters. It is observed that the LBIC measurements introduce artefacts such as shift in peak position with increasing laser power. Simulation of LBIC signal as a function of characteristic length Lc of photo-generated carriers and for different beam diameters has resulted in the observed peak shifts, thus attributed to the finite size of the beam. Further, the idea of capacitively coupled contacts has been extended to contactless measurements using pressure contacts with an oxidized aluminium electrodes. This technique avoids the contagious sample processing steps, which may introduce unintentional defects and contaminants into the material and devices under observation. Thus, we present here, the remote contact LBIC as a practically non-destructive tool in the evaluation of device parameters and welcome its use during fabrication steps.
Charge compensation of head-to-head and tail-to-tail domain walls in barium titanate and its influence on conductivity
Authors: Zuo Yinan , Genenko Yuri A. , Xu Bai-Xiang
Published: July 2014

The effect of the polarization charge compensation by ionic and electronic space charges on domain properties in ferroelectrics with semiconducting features is considered, in particular, the conductivity of head-to-head and tail-to-tail domain walls is studied. It is shown that the domain wall conductivity that is enhanced by electrons or holes depends on the configuration and the types of domains as well as on the energy levels and concentrations of the defects involved. Phase field simulation results are used to explain recent equivocal experimental results on conductivity of charged domain walls in different ferroelectrics.
Spin current formation at the graphene/Pt interface for magnetization manipulation in magnetic nanodots
Authors: Shikin A. M. , Rybkina A. A. , Rybkin A. G. , Klimovskikh I. I. , Skirdkov P. N. , Zvezdin K. A. , Zvezdin A. K.
Published: July 2014

Spin electronic structure of the Graphene/Pt interface has been investigated. A large induced spin-orbit splitting (∼80 meV) of graphene π states with formation of non-degenerated Dirac-cone spin states at the K¯-point of the Brillouin zone crossed with spin-polarized Pt 5d states at Fermi level was found. We show that this spin structure can be used as a spin current source in spintronic devices. By theoretical estimations and micromagnetic modeling based on the experimentally observed spin-orbit splitting, we demonstarte that the induced intrinsic magnetic field in such structure might be effectively used for induced remagnetization of the (Ni-Fe)-nanodots arranged atop the interface.
Resolution dependence of petrophysical parameters derived from X-ray tomography of chalk
Authors: Müter D. , Sørensen H. O. , Jha D. , Harti R. , Dalby K. N. , Suhonen H. , Feidenhans'l R. , Engstrøm F. , Stipp S. L. S.
Published: July 2014

X-ray computed tomography data from chalk drill cuttings were taken over a series of voxel dimensions, ranging from 320 to 25 nm. From these data sets, standard petrophysical parameters (porosity, surface area, and permeability) were derived and we examined the effect of the voxel dimension (i.e., image resolution) on these properties. We found that for the higher voxel dimensions, they are severely over or underestimated, whereas for 50 and 25 nm voxel dimension, the resulting values (5%–30% porosity, 0.2–2 m2/g specific surface area, and 0.06–0.34 mD permeability) are within the expected range for this type of rock. We compared our results to macroscopic measurements and in the case of surface area, also to measurements using the Brunauer-Emmett-Teller (BET) method and found that independent of the degree of compaction, the results from tomography amount to about 30% of the BET method. Finally, we concluded that at 25 nm voxel dimension, the essential features of the nanoscopic pore network in chalk are captured but better resolution is still needed to derive surface area.
Manganese induces oligomerization to promote down-regulation of the intracellular trafficking receptor used by Shiga toxin
Authors: Tewari Ritika , Jarvela Timothy , Linstedt Adam D.
Published: July 2014

Manganese (Mn) protects cells against lethal doses of purified Shiga toxin by causing the degradation of the cycling transmembrane protein GPP130, which the toxin uses as a trafficking receptor. Mn-induced GPP130 down-regulation, in addition to being a potential therapeutic approach against Shiga toxicosis, is a model for the study of metal-regulated protein sorting. Significantly, however, the mechanism by which Mn regulates GPP130 trafficking is unknown. Here we show that a transferable trafficking determinant within GPP130 bound Mn and that Mn binding induced GPP130 oligomerization in the Golgi. Alanine substitutions blocking Mn binding abrogated both oligomerization of GPP130 and GPP130 sorting from the Golgi to lysosomes. Further, oligomerization was sufficient because forced aggregation, using a drug-controlled polymerization domain, redirected GPP130 to lysosomes in the absence of Mn. These experiments reveal metal-induced oligomerization as a Golgi sorting mechanism for a medically relevant receptor for Shiga toxin.
Indaziflam Herbicidal Action: A Potent Cellulose Biosynthesis Inhibitor
Authors: Brabham Chad , Lei Lei , Gu Ying , Stork Jozsef , Barrett Michael , DeBolt Seth
Published: July 2014

Cellulose biosynthesis is a common feature of land plants. Therefore, cellulose biosynthesis inhibitors (CBIs) have a potentially broad-acting herbicidal mode of action and are also useful tools in decoding fundamental aspects of cellulose biosynthesis. Here, we characterize the herbicide indaziflam as a CBI and provide insight into its inhibitory mechanism. Indaziflam-treated seedlings exhibited the CBI-like symptomologies of radial swelling and ectopic lignification. Furthermore, indaziflam inhibited the production of cellulose within <1 h of treatment and in a dose-dependent manner. Unlike the CBI isoxaben, indaziflam had strong CBI activity in both a monocotylonous plant (Poa annua) and a dicotyledonous plant (Arabidopsis [Arabidopsis thaliana]). Arabidopsis mutants resistant to known CBIs isoxaben or quinoxyphen were not cross resistant to indaziflam, suggesting a different molecular target for indaziflam. To explore this further, we monitored the distribution and mobility of fluorescently labeled CELLULOSE SYNTHASE A (CESA) proteins in living cells of Arabidopsis during indaziflam exposure. Indaziflam caused a reduction in the velocity of YELLOW FLUORESCENT PROTEIN:CESA6 particles at the plasma membrane focal plane compared with controls. Microtubule morphology and motility were not altered after indaziflam treatment. In the hypocotyl expansion zone, indaziflam caused an atypical increase in the density of plasma membrane-localized CESA particles. Interestingly, this was accompanied by a cellulose synthase interacting1-independent reduction in the normal coincidence rate between microtubules and CESA particles. As a CBI, for which there is little evidence of evolved weed resistance, indaziflam represents an important addition to the action mechanisms available for weed management.
Molecular Cloning and Characterization of a Geranyl Diphosphate-Specific Aromatic Prenyltransferase from Lemon
Authors: Munakata Ryosuke , Inoue Tsuyoshi , Koeduka Takao , Karamat Fazeelat , Olry Alexandre , Sugiyama Akifumi , Takanashi Kojiro , Dugrand Audray , Froelicher Yann , Tanaka Ryo , Uto Yoshihiro , Hori Hitoshi , Azuma Jun-Ichi , Hehn Alain , Bourgaud Frédéric , Yazaki Kazufumi
Published: July 2014

Prenyl residues confer divergent biological activities such as antipathogenic and antiherbivorous activities on phenolic compounds, including flavonoids, coumarins, and xanthones. To date, about 1,000 prenylated phenolics have been isolated, with these compounds containing various prenyl residues. However, all currently described plant prenyltransferases (PTs) have been shown specific for dimethylallyl diphosphate as the prenyl donor, while most of the complementary DNAs encoding these genes have been isolated from the Leguminosae. In this study, we describe the identification of a novel PT gene from lemon (Citrus limon), ClPT1, belonging to the homogentisate PT family. This gene encodes a PT that differs from other known PTs, including flavonoid-specific PTs, in polypeptide sequence. This membrane-bound enzyme was specific for geranyl diphosphate as the prenyl donor and coumarin as the prenyl acceptor. Moreover, the gene product was targeted to plastid in plant cells. To our knowledge, this is the novel aromatic PT specific to geranyl diphosphate from citrus species.
Deconstructing resistance to organizational change: a social representation theory approach
Authors: Andersén Jim , Andersén Annelie
Published: July 2014

Purpose

– The purpose of this paper is to illustrate how social representation theory (SRT) can be used to understand the concept of resistance to change. SRT is a growing theory in social psychology research. SRT is about how individuals co-construct representations of various objects in different social settings. These social representations govern the attitudes and actions of individuals and groups. In spite of the growing interest in SRT in various fields, no studies have used SRT to understand resistance to organizational change.

Design/methodology/approach

– This study reviews the relevant literature on resistance to change and SRT to develop a conceptual framework for understanding resistance from the standpoint of SRT.

Findings

– The authors develop a model that illustrates how three interrelated objects, i.e. the organizational process and the pre-and post-change situation, are co-constructed in social contexts. Also, the authors discuss how representations of these objects can co-exist (cognitive polyphasia). Our study illustrates the complexity of resistance to change by deconstructing the concept.

Originality/value

– Application of SRT to analyze resistance to organizational change is a novel approach that provides several new insights. For example, where most publications regard advocates of change as sense-givers in the change recipient’s sense-making process, the authors argue for a more constructionist approach. Thus, all actors involved in the change process will affect each other and together co-construct the social representations. These social representations govern attitudes to change.
Culpable insiders – the enemy within, the victim without
Authors: Simser Jeffrey
Published: July 2014

Purpose

– The purpose of this paper is to explore the role of the culpable insider and the predatory criminal in fraud and deception.

Design/methodology/approach

– Two groupings of fraud are considered in this paper. Insider fraud consists of a person within an organization misusing their position for corrupt self-dealing, asset misappropriation and financial statement fraud. Case studies are discussed, offering differing perspectives on the role of insiders. Fraudsters use technology, like malware, to take on the mantle of an insider to facilitate their larceny. This paper also looks at the role of the insider with predatory frauds.

Findings

– Most enterprises, be they public entities or private firms, are at risk of internal fraud. Internal financial controls are the first line of defence. In tougher economic times, when enterprises run on the tightest of margins, control mechanisms are at risk of being weakened at the altar of efficiency. Firms can also adopt cultures that deter frauds, either through policies on whistle-blowers or through simple employee screening procedures. For predatory frauds, the basic warning flag can be summed up with the cliché: if something seems too good to be true, it probably is.

Originality/value

– This paper synthesizes research on fraud and the role that an insider can play as well as the role of a predatory fraudster.
Mis-alignment between IT knowledge/skills importance and IT knowledge/skills integration level into the accounting curriculum in Egypt
Authors: M. Sabry Nokhal Ayman , Azizi Ismail Noor
Published: July 2014

Purpose

– This paper aims to investigate the alignment between the information technology (IT) knowledge/skills importance or required by the business environment and the IT knowledge/skills integration level in the accounting curriculum in the specific context of Egyptian universities.

Design/methodology/approach

– Data were collected from a survey of 249 accountant lecturers by emails.

Findings

– The results indicate that the most important technologies are generalized audit software, embedded audit modules/real-time modules, small business accounting software, computer-aided systems engineering tools, test data and tax return preparation software, and the most technologies integrated in the accounting curriculum in Egypt are wording processing, electronic spreadsheets and electronic presentations. These results mean there is a gap between what is required and what is integrated in the accounting curriculum.

Originality/value

– This study is the first attempt to investigate the alignment between the IT required and integrated in the accounting curriculum, especially in Egypt.
The use of strong and weak form sustainability to assist in rate development for the valuation of exhaustible resources (part II)
Authors: Grissom T.V. , McCord M. , Davis P. , McCord J.
Published: July 2014

Purpose

–This paper is the second of a two part series which offers new theoretical and empirical insights investigating the rates structures appropriate for exhaustible resources with a particular emphasis on urban land, based upon the differentiation of strong- and weak-form sustainability concepts constrained by the objectives of the sustainable criterion of Daly and Cobb (1994). The integration of the concepts and objectives allow the theoretical formulation of discount and capitalization rates that can be empirically tested. This empirical application employs data from 12 diverse national economies. The paper aims to discuss these issues.

Design/methodology/approach

– The paper integrates the concepts of discount rate development for environmental and long-term assets and discounted utility analysis to the policy concerns associated with the valuation of public and sustainable resources. The new approach empirically shows the diverse issues of competing sustainable objectives across nations.

Findings

– The potential and degree of strong-form or weak-form sustainability application in each nation enabled the identification as to whether alternative capital as defined by the modified Ramsey model used per nation, or the marginal rate of resource return as defined by strong form objective of a constant natural resource endowment, can identify which form of capital becomes the major constraint on the resource valuation and allocation decision appropriate within each nation. The findings showed constraints on nation resource endowments relative to population needs and the culture preferences endemic across nations.

Originality/value

– The findings serve as a basis for future research on the optimal levels of sustainable development appropriate for different nations, the impactions of the timing and level of capital re-switching associated with the application of strong- or weak-form sustainability and the develop of rate and risk measures that can assist in the consideration of sustainable resource as a distinct asset class.
Review article: the nutritional and pharmacological consequences of obesity surgery
Authors: Stein J. , Stier C. , Raab H. , Weiner R.
Published: July 2014

Background

Obesity surgery is acknowledged as a highly effective therapy for morbidly obese patients. Beneficial short‐term effects on common comorbidities are practically undisputed, but a growing data pool from long‐term follow‐up reveals increasing evidence of potentially severe nutritional and pharmacological consequences.

Aims

To assess the prevalence, causes and symptoms of complications after obesity surgery, to elucidate and compare therapy recommendations for macro‐ and micronutrient deficiencies, and to explore surgically‐induced effects on drug absorption and bioavailability, discussing ramifications for long‐term therapy and prophylaxis.

Methods

PubMed, Embase and MEDLINE were searched using terms including, but not limited to, bariatric surgery, gastric bypass, obesity surgery and Roux‐en‐Y, coupled with secondary search terms, e.g. anaemia, micronutrients, vitamin deficiency, bacterial overgrowth, drug absorption, pharmacokinetics, undernutrition. All studies in English, French or German published January 1980 through March 2014 were included.

Results

Macro‐ and micronutrient deficiencies are common after obesity surgery. The most critical, depending on surgical technique, are hypoalbuminemia (3–18%) and deficiencies of vitamins B1 (≤49%), B12 (19–35%) and D (25–73%), iron (17–45%) and zinc (12–91%). Many drugs commonly administered to obese patients (e.g. anti‐depressants, anti‐microbials, metformin) are subject to post‐operative and/or PPI‐associated changes affecting bioavailability and absorption.

Conclusions

Complications are associated with pre‐operative and/or post‐operative malnutrition or procedure‐related changes in intake, absorption and drug bioavailability. The high prevalence of nutrient deficiencies after obesity surgery makes life‐long nutritional monitoring and supplementation essential. Post‐operative changes to drug absorption and bioavailability in bariatric patients cast doubt on the validity of standard drug dosage and administration recommendations.
Development of integument and cutaneous glands in larval, juvenile and adult toads (Rhinella granulosa): a morphological and morphometric study
Authors: Chammas Sérgio M. , Carneiro Sylvia M. , Ferro Rafael S. , Antoniazzi Marta M. , Jared Carlos
Published: July 2014

In this study, the development of integument and cutaneous glands in the toad Rhinella granulosa (Bufonidae) at different larval stages and in postmetamorphic and adult forms was examined. The analyses were conducted using histological, ultrastructural and morphometric methods. The results showed that cellular aggregations of precursor epidermal glands start to appear in stage 31 of (Herpetologica, 16, 1960 and 183) and then proliferate and invade the dermis. After stage 41, granular and mucous glands are very similar to those found in adults. The granular glands are syncytial and are surrounded by a distinct layer of myoepithelial cells. In the region of parotoid macroglands, the granular glands accumulate and their alveoli progressively increase until they reach adult size. An analysis by scanning electron microscopy showed the inner distribution of the syncytial nuclei and the myoepithelial cells. The morphological changes observed in the integument of tadpoles are associated with the gradual adaptation to terrestrial environments by preparing the individual for future chemical defence against predators and micro‐organisms.
Prevalence of ciprofloxacin‐resistant Enterobacteriaceae in the intestinal flora of patients undergoing transrectal prostate biopsy in Norwich, UK
Authors: Hanna Marcelino Yazbek , Tremlett Catherine , Josan Gurvir , Eltom Ali , Mills Robert , Rochester Mark , Livermore David M.
Published: July 2014

Objective

To determine the efficacy of fluoroquinolone prophylaxis in patients undergoing transrectal ultrasonography (TRUS)‐guided biopsy of the prostate in the Norwich population, and its correlation with ciprofloxacin resistance in the faecal flora. We also aimed to determine the usefulness of a pre‐biopsy rectal screen for resistant bacteria in these patients.

Patients and Methods

The incidence and microbiology of sepsis after TRUS‐guided prostate biopsies between 2007 and 2011 was audited retrospectively. Subsequently, in 2012, a prospective study was performed, collecting the same data but also culturing rectal swabs from all patients undergoing TRUS‐guided biopsy, with a post‐biopsy follow‐up period of 6 months. All patients were given prophylactic oral ciprofloxacin, as per Trust policy (750 mg 1 h before biopsy, followed by 250 mg twice daily for 3 subsequent days).

Results

Between 2007 and 2011, 3600 patients underwent TRUS‐guided biopsy. Among these, 11 (0.3%) were admitted to hospital for post‐biopsy related sepsis but only 4 (0.1%) had ciprofloxacin‐resistant Escherichia coli confirmed from blood cultures: three had ciprofloxacin‐susceptible Enterobacteriaceae, and four had no ciprofloxacin susceptibility data. In 2012, 10 (3.7%) of 267 patients sampled before biopsy had ciprofloxacin‐resistant E. coli recovered on rectal swab culture but none of these men presented with post‐biopsy sepsis; during the 6‐month follow‐up period, seven patients were diagnosed with urinary tract infections.

Conclusion

Ciprofloxacin‐resistant Enterobacteriaceae remains rare in the intestinal flora of the Norwich TRUS population, meaning that the drug remains adequate as prophylaxis. Pre‐biopsy rectal swabs may be useful for individual departments to periodically assess their own populations and to ensure their antibiotic policy remains valid. In populations where resistance is known to be highly prevalent, pre‐biopsy rectal swabs can help guide addition of further antibiotics to prevent post‐biopsy septicaemia.
Factors affecting breast milk composition and potential consequences for development of the allergic phenotype
Authors: Munblit D. , Boyle R. J. , Warner J. O.
Published: July 2014

There is conflicting evidence on the protective role of breastfeeding in relation to allergic sensitization and disease. The factors in breast milk which influence these processes are still unclear and under investigation. We know that colostrum and breast milk contain a variety of molecules which can influence immune responses in the gut‐associated lymphoid tissue of a neonate. This review summarizes the evidence that variations in colostrum and breast milk composition can influence allergic outcomes in the infant, and the evidence that maternal and environmental factors can modify milk composition. Taken together, the data presented support the possibility that maternal dietary interventions may be an effective way to promote infant health through modification of breast milk composition.
The status of 25‐hydroxyvitamin D across the spectrum of glucose tolerance among middle‐aged and elderly Chinese individuals
Authors: Guan Conghui , Zhen Donghu , Tang Xulei , Yang Xiaomei , Zhu Tengfei , Fu Songbo , Tian Yunling
Published: July 2014

Context

Although vitamin D status and its inverse association with diabetes among White people have been recognized, little research on vitamin D status has been well conducted in Chinese individuals based on glucose tolerance.

Objective

To compare the vitamin D status of Chinese individuals aged 40–75 years based on the glucose tolerance status.

Design and methods

Serum 25OHD was measured in a cross‐sectional sample of 10 038 individuals aged 40–75 years from Lanzhou city, which is located in western China.

Results

People with normal glucose tolerance (NGT, n = 4744), prediabetes (n = 2808) or diabetes (n = 2486) aged 40–75 years were included in the study. The difference in 25OHD concentration between people with NGT and prediabetes was not significant (16·5 vs 16·0 ng/ml, P = 0·773), but the 25OHD concentration of diabetes was higher than that of subjects with NGT (16·5 vs 16·5 ng/ml, P = 0·025) and prediabetes (16·5 vs 16·0 ng/ml, P = 0·032) after adjusting confounders. There was no difference in the prevalence of vitamin D deficiency between people with NGT and diabetes (74·7% vs 74·0%, P = 0·535), but the prevalence of vitamin D deficiency of prediabetes was higher than that of people with NGT (77·0% vs 74·7%, P = 0·024) and diabetes (77·0% vs 74·0%, P = 0·012).

Conclusions

Although vitamin D status was significantly different across the spectrum of glucose tolerance in middle‐aged and elderly Chinese individuals, the difference was not clinically significant. The results, however, highlight the very high prevalence of vitamin D deficiency in this population and should raise the awareness of this important public health issue among health‐care providers.
Association of Learning Styles with Research Self‐Efficacy: Study of Short‐Term Research Training Program for Medical Students
Authors: Dumbauld Jill , Black Michelle , Depp Colin A. , Daly Rebecca , Curran Maureen A. , Winegarden Babbi , Jeste Dilip V.
Published: July 2014

Purpose

With a growing need for developing future physician scientists, identifying characteristics of medical students who are likely to benefit from research training programs is important. This study assessed if specific learning styles of medical students, participating in federally funded short‐term research training programs, were associated with research self‐efficacy, a potential predictor of research career success.

Method

Seventy‐five first‐year medical students from 28 medical schools, selected to participate in two competitive NIH‐supported summer programs for research training in aging, completed rating scales to evaluate learning styles at baseline, and research self‐efficacy before and after training. We examined associations of individual learning styles (visual‐verbal, sequential‐global, sensing‐intuitive, and active‐reflective) with students’ gender, ranking of medical school, and research self‐efficacy.

Results

Research self‐efficacy improved significantly following the training programs. Students with a verbal learning style reported significantly greater research self‐efficacy at baseline, while visual, sequential, and intuitive learners demonstrated significantly greater increases in research self‐efficacy from baseline to posttraining. No significant relationships were found between learning styles and students’ gender or ranking of their medical school.

Conclusions

Assessments of learning styles may provide useful information to guide future training endeavors aimed at developing the next generation of physician‐scientists.
Novel techniques for gastric variceal obliteration
Authors: Fujii‐Lau Larissa L. , Law Ryan , Wong Kee Song Louis M. , Levy Michael J.
Published: July 2014

Acute hemorrhage related to gastric varices (GV) is more severe and often more difficult to immediately treat upon detection, leading to a poorer patient prognosis, as compared to esophageal variceal bleeding. Currently, the recommended treatment of bleeding GV is endoscopic cyanoacrylate injection and transjugular intrahepatic portosystemic shunt placement for endoscopic failures. Newer endoscopic (e.g. hemospray) and endosonographic (e.g. coil injection, glue obliteration, or combined coil and glue injection) techniques have been developed to offer an alternative treatment and improve patient outcome. The present article serves to review the endoscopic, endosonographic, and interventional radiological techniques used to treat GV and their clinical applications.
Increasing small conductance Ca2+‐activated potassium channel activity reverses ischemia‐induced impairment of long‐term potentiation
Authors: Orfila J. E. , Shimizu K. , Garske A. K. , Deng G. , Maylie J. , Traystman R. J. , Quillinan N. , Adelman J. P. , Herson P. S.
Published: July 2014

Global cerebral ischemia following cardiac arrest and cardiopulmonary resuscitation (CA/CPR) causes injury to hippocampal CA1 pyramidal neurons and impairs cognition. Small conductance Ca2+‐activated potassium channels type 2 (SK2), expressed in CA1 pyramidal neurons, have been implicated as potential protective targets. Here we showed that, in mice, hippocampal long‐term potentiation (LTP) was impaired as early as 3 h after recovery from CA/CPR and LTP remained impaired for at least 30 days. Treatment with the SK2 channel agonist 1‐Ethyl‐2‐benzimidazolinone (1‐EBIO) at 30 min after CA provided sustained protection from plasticity deficits, with LTP being maintained at control levels at 30 days after recovery from CA/CPR. Minimal changes in glutamate release probability were observed at delayed times after CA/CPR, implicating post‐synaptic mechanisms. Real‐time quantitative reverse transcriptase‐polymerase chain reaction indicated that CA/CPR did not cause a loss of N‐methyl‐D‐aspartate (NMDA) receptor mRNA at 7 or 30 days after CA/CPR. Similarly, no change in synaptic NMDA receptor protein levels was observed at 7 or 30 days after CA/CPR. Further, patch‐clamp experiments demonstrated no change in functional synaptic NMDA receptors at 7 or 30 days after CA/CPR. Electrophysiology recordings showed that synaptic SK channel activity was reduced for the duration of experiments performed (up to 30 days) and that, surprisingly, treatment with 1‐EBIO did not prevent the CA/CPR‐induced loss of synaptic SK channel function. We concluded that CA/CPR caused alterations in post‐synaptic signaling that were prevented by treatment with the SK2 agonist 1‐EBIO, indicating that activators of SK2 channels may be useful therapeutic agents to prevent ischemic injury and cognitive impairments.
Multiple proteins from ejaculated and epididymal porcine spermatozoa bind glycan motifs found in the oviduct
Authors: Silva E. , Kadirvel G. , Jiang R. , Bovin N. , Miller D.
Published: July 2014

Previously, we demonstrated that porcine spermatozoa bind selectively to Lewisx (LeX) and bi‐antennary α2‐6 sialylated N‐acetyllactosamine (bi‐SiaLN) glycan motifs found in the oviduct. Recognition of these motifs mediates sperm binding to oviduct epithelial cells to form a reservoir. Here, we characterize proteins that bind to LeX and bi‐SiaLN in ejaculated and cauda epididymal spermatozoa. Fluoresceinated 3′‐O‐sulphated‐LeX (suLeX) and bi‐SiaLN were used to locate the binding proteins on spermatozoa. Binding to N‐acetyllactosamine (LN), a glycan that spermatozoa bind less, was assessed as a control. Over 60% of ejaculated and epididymal spermatozoa bound to suLeX and bi‐SiaLN, but only 25% bound to LN. Specific binding to suLeX and bi‐SiaLN required divalent cations. Fluoresceinated suLeX bound mostly to the plasma membrane at the apex of the head, whereas bi‐SiaLN bound to a broader area of the head. Further characterization of receptors was accomplished by probing, with specific glycans, sperm proteins that had been separated by SDS‐PAGE and transferred to blots. Glycan blot assays identified several suLeX‐binding bands that migrated as 12–250 kDa. Migration of some of the bands that bound bi‐SiaLN was similar to those that bound suLeX. A 12‐kDa band protein was detected in seminal fluid and ejaculated spermatozoa, but absent in epididymal spermatozoa. In summary, we determined that: (i) multiple glycan‐binding proteins recognize suLeX and bi‐SiaLN motifs, (ii) specific binding required divalent cations and (iii) glycan‐binding proteins were identified before and after sperm contact with accessory gland fluids. While the identity of these molecules is still unknown, this information predicts characteristics of the authentic oviduct suLeX and bi‐SiaLN receptors on spermatozoa.
Love Troubles: Human Attachment and Biomedical Enhancements
Authors: Nyholm Sven
Published: July 2014

In fascinating recent work, Julian Savulescu and his various co‐authors argue that human love is one of the things we can improve upon using biomedical enhancements. Is that so? This article first notes that Savulescu and his co‐authors mainly treat love as a means to various other goods. Love, however, is widely regarded as an intrinsic good. To investigate whether enhancements can produce the distinctive intrinsic good of love, this article does three things. Drawing on Philip Pettit's recent discussion of ‘robustly demanding goods’, it asks what exactly we intrinsically desire in seeking love; it considers four possible outcomes involving attachment‐enhancements and attachments; and it considers two different pieces of news we might receive about our lovers' attachment to us (that it is, or that it is not, sustained with the help of enhancement‐technologies). Enhancement‐sustained attachment, it is concluded, is less desirable than the intrinsic good of love.
The circadian clock and defence signalling in plants
Authors: Sharma Mayank , Bhatt Deepesh
Published: July 2014

The circadian clock is the internal time‐keeping machinery in higher organisms. Cross‐talk between the circadian clock and a diverse range of physiological processes in plants, including stress acclimatization, hormone signalling, photomorphogenesis and defence signalling, is currently being explored. Recent studies on circadian clock genes and genes involved in defence signalling have indicated a possible reciprocal interaction between the two. It has been proposed that the circadian clock shapes the outcome of plant–pathogen interactions. In this review, we highlight the studies carried out so far on two model plant pathogens, namely Pseudomonas syringae and Hyaloperonospora arabidopsidis, and the involvement of the circadian clock in gating effector‐triggered immunity and pathogen‐associated molecular pattern‐triggered immunity. We focus on how the circadian clock gates the expression of various stress‐related transcripts in a prolific manner to enhance plant fitness. An understanding of this dynamic relationship between clock and stress will open up new avenues in the understanding of endogenous mechanisms of defence signalling in plants.
Identification and characterization of microRNAs in oilseed rape (Brassica napus) responsive to infection with the pathogenic fungus Verticillium longisporum using Brassica AA (Brassica rapa) and CC (Brassica oleracea) as reference genomes
Authors: Shen Dan , Suhrkamp Ina , Wang Yu , Liu Shenyi , Menkhaus Jan , Verreet Joseph‐Alexander , Fan Longjiang , Cai Daguang
Published: July 2014

Verticillium longisporum, a soil‐borne pathogenic fungus, causes vascular disease in oilseed rape (Brassica napus). We proposed that plant microRNAs (miRNAs) are involved in the plant–V. longisporum interaction.

To identify oilseed rape miRNAs, we deep‐sequenced two small RNA libraries made from V. longisporum infected/noninfected roots and employed Brassica rapa and Brassica oleracea genomes as references for miRNA prediction and characterization.

We identified 893 B. napus miRNAs representing 360 conserved and 533 novel miRNAs, and mapped 429 and 464 miRNAs to the AA and CC genomes, respectively. Microsynteny analysis with the conserved miRNAs and their flanking protein coding sequences revealed 137 AA–CC genome syntenic miRNA pairs and 61 AA and 42 CC genome‐unique miRNAs. Sixty‐two miRNAs were responsive to the V. longisporum infection. We present data for specific interactions and simultaneously reciprocal changes in the expression levels of the miRNAs and their targets in the infected roots. We demonstrate that miRNAs are involved in the plant–fungus interaction and that miRNA168‐Argonaute 1 (AGO1) expression modulation might act as a key regulatory module in a compatible plant–V. longisporum interaction.

Our results suggest that V. longisporum may have evolved a virulence mechanism by interference with plant miRNAs to reprogram plant gene expression and achieve infection.
Src Regulates Sequence‐Dependent Beta‐2 Adrenergic Receptor Recycling via Cortactin Phosphorylation
Authors: Vistein Rachel , Puthenveedu Manojkumar A.
Published: July 2014

The recycling of internalized signaling receptors, which has direct functional consequences, is subject to multiple sequence and biochemical requirements. Why signaling receptors recycle via a specialized pathway, unlike many other proteins that recycle by bulk, is a fundamental unanswered question. Here, we show that these specialized pathways allow selective control of signaling receptor recycling by heterologous signaling. Using assays to visualize receptor recycling in living cells, we show that the recycling of the beta‐2 adrenergic receptor (B2AR), a prototypic signaling receptor, is regulated by Src family kinases. The target of Src is cortactin, an essential factor forB2ARsorting into specialized recycling microdomains on the endosome. Phosphorylation of a single cortactin residue,Y466, regulates the rate of fission ofB2ARrecycling vesicles from these microdomains and, therefore, the rate of delivery ofB2ARto the cell surface. Together, our results indicate that actin‐stabilized microdomains that mediate signaling receptor recycling can serve as a functional point of convergence for crosstalk between signaling pathways.
Digit patterning is controlled by a Bmp-Sox9-Wnt Turing network modulated by morphogen gradients
Authors: Raspopovic J. , Marcon L. , Russo L. , Sharpe J.
Published: July 2014

How do fingers know where to grow?

Most researchers today believe that each finger forms because of its unique position within the early limb bud. However, 30 years ago, developmental biologists proposed that the arrangement of fingers followed the Turing pattern, a self-organizing process during early embryo development. Raspopovicet al.provide evidence to support a Turing mechanism (see the Perspective by Zuniga and Zeller). They reveal that Bmp and Wnt signaling pathways, together with the gene Sox9, form a Turing network. The authors used this network to generate a computer model capable of accurately reproducing the patterns that cells follow as the embryo grows fingers.

Science, this issue p.566; see also p.516
The beat of young stars
Authors: Stahler Steven , Palla Francesco
Published: July 2014

Pulsations from young stars provide a new chronometer for stellar evolution

[Also see Report by

Zwintz
et al.

]
Genetic Identification of Rickettsial Isolates from Fatal Cases of Brazilian Spotted Fever and Comparison with Rickettsia rickettsii Isolates from the American Continents
Authors: Labruna Marcelo B. , Santos Fabiana C. P. , Ogrzewalska Maria , Nascimento Elvira M. M. , Colombo Silvia , Marcili Arlei , Angerami Rodrigo N.
Published: July 2014

Fifteen bacterial isolates from spotted fever group rickettsiosis in Brazil were genetically identified as
Rickettsia rickettsii
. In a phylogenetic analysis with other
R. rickettsii
isolates from GenBank, the Central/South American isolates showed low polymorphism and formed a clade distinct from two North American clades, with the North American clades having greater in-branch polymorphism.
Tumour response following high-dose intratumoural application ofViscum albumon a patient with adenoid cystic carcinoma
Authors: Werthmann Paul Georg , Helling Dieter , Heusser Peter , Kienle Gunver Sophia
Published: July 2014

Adenoid cystic carcinoma (ACC) is a rare type of cancer that typically originates in the salivary glands. Surgical removal can lead to functional loss and psychological distress.Viscum albumextract (VAE) is a herbal remedy with dose-dependent cytotoxic, apoptogenic and immunological effects. In some case reports, tumour regression has been observed following high-dose local applications of VAE. An active 88-year-old man with fast-growing ACC of the hard palate refused surgical removal and received high-dose intratumoural injections of VAE (alone) over a 10-month period. The tumour decreased in size, softened and loosened from its surroundings. A biopsy during the course showed inflammation. The patient remained well and without functional limitations during the therapy and follow-up period (5 months). VAE produced no reported side effects. This aged patient exemplifies a satisfying course of ACC under VAE resulting in good quality of life and partial tumour regression.
Dynamic pattern of suicide in Australia, 1986–2005: a descriptive-analytic study
Authors: Qi Xin , Hu Wenbiao , Page Andrew , Tong Shilu
Published: July 2014

Objective

This study explores the spatiotemporal variations of suicide across Australia from 1986 to 2005, discusses the reasons for dynamic changes, and considers future suicide research and prevention strategies.

Design

Suicide (1986–2005) and population data were obtained from the Australian Bureau of Statistics. A series of analyses were conducted to examine the suicide pattern by sex, method and age group over time and geography.

Results

Differences in suicide rates across sex, age groups and suicide methods were found across geographical areas. Male suicides were mainly completed by hanging, firearms, gases and self-poisoning. Female suicides were primarily completed by hanging and self-poisoning. Suicide rates were higher in rural areas than in urban areas (capital cities and regional centres). Suicide rates by firearms were higher in rural areas than in urban areas, while the pattern for self-poisoning showed the reverse trend. Suicide rates had relatively stable trend for the total population and those aged between 15 and 54, while suicide decreased among 55 years and over during the study period. There was a decrease in suicides by firearms during the study period especially after 1996 when a new firearm control law was implemented, while suicide by hanging continued to increase. Areas with a high proportion of indigenous population (eg, northwest of Queensland and top north of the Northern Territory) had shown a substantial increase in suicide incidence after 1995.

Conclusions

Suicide rates varied over time and space and across sexes, age groups and suicide methods. This study provides detailed patterns of suicide to inform suicide control and prevention strategies for specific subgroups and areas of high and increased risk.
Incompressible lattice Boltzmann model for axisymmetric flows through porous media
Authors: Rong Fumei , Shi Baochang
Published: July 2014

In this paper, an axisymmetric LBE model for incompressible flows through porous media is proposed. In this model, the influence of density change caused by large pressure difference can be overcome by replacing density distribution function with pressure distribution function. A more simple processing format for external force is introduced so as to make the involved method in this paper more perfect. The coupling between flow velocity and pressure also can be significantly reduced when calculating the macroscopic quantities. Good agreement between the analytical solution and numerical results is also obtained based on this model and it also can provide guidance for other problem with such complicated force forms.
INVESTIGATION OF CYCLIC SOFTENING BEHAVIOR OF SHOT PEENED S30432 AUSTENITIC STAINLESS STEEL BY X-RAY DIFFRACTION METHOD
Authors: ZHAN KE , ZHENG XUE JUN , HAN HAO , FENG QIANG , JIANG CHUAN HAI
Published: July 2014

Microstructure evolution of shot peened S30432 austenitic stainless steel under external loading was investigated by X-ray diffraction method. The domain size, micro-strain, and dislocation density were calculated by Voigt method and Williamson method, respectively. The results show that the dislocation density decreases sharply in initial stage, then undergoes a stable stage, following by an increase in the end. It reveals that cyclic softening happened during cyclic loading, and it can ascribe to the high dislocation density after shot peening (SP). This study suggests that cyclic softening behavior may need to take into consideration when considering the strengthening effect of SP.