bluuebunny/crossref_metadata_2025 huggingface dataset:
Broadband control of the viscoelasticity of ferroelectrics via domain switching
Authors: Wojnar C. S. , le Graverend J.-B. , Kochmann D. M.
Published: October 2014

We show that the viscoelastic properties of polycrystalline ferroelectric ceramics can be significantly altered over a wide range of mechanical frequencies when domain switching is controlled by cyclic electric fields. The dynamic stiffness of lead zirconate titanate is shown to vary by more than 30%, while damping increases by an order of magnitude. Experimental results are interpreted by the aid of a continuum-mechanics model that captures the nonlinear electro-mechanically coupled material response for the full electric hysteresis.
Prospects of poly (vinyl alcohol)/Chitosan/poly (styrene sulfonic acid) and montmorillonite Cloisite®30B clay composite membrane for direct methanol fuel cells
Authors: Gaur Surendra Singh , Dhar Prodyut , Kumar Amit , Katiyar Vimal
Published: October 2014

A proton conducting polymer electrolyte nanocomposite membrane has been fabricated by using poly (vinyl alcohol) (PVA), Chitosan, and poly (styrene sulfonic acid) (PSSA) polymers and montmorillonite Cloisite®30B clay with the objective of its application in direct methanol fuel cells. Comparative studies of a PVA/PSSA/Chitosan/Cloisite30B clay composite membrane with a base PVA/PSSA membrane has been carried out by using thermal gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, X-ray diffraction, methanol permeability and proton conductivity measurements. Properties of the membrane have been compared with Nafion®117 at identical test conditions. Methanol permeability of the PVA/PSSA/Chitosan/Cloisite30B clay composite membrane has been found to be superior to that of PVA/PSSA as well as Nafion117 membranes. Water uptake of the membrane is much higher compared to the Nafion117 membrane. Proton conductivity of the membrane has been found in the range of 10−2 S cm−1 at room temperature and 70% relative humidity. Selectivity of the membrane is in the range of 104 S s cm−3, which is better than that of Nafion117.
Photo-activated oxygen sensitivity of graphene at room temperature
Authors: Berholts Artjom , Kahro Tauno , Floren Aare , Alles Harry , Jaaniso Raivo
Published: October 2014

Photo-induced changes in the electrical conductivity and the sensitivity to oxygen gas of graphene sheets grown by chemical vapor deposition and transferred onto Al2O3 and SiO2 thin film substrates were studied at ambient conditions. The pristine graphene sensors were initially completely insensitive to oxygen gas at room temperature but showed significant (up to 100%) response when illuminated with weak ultraviolet (300 nm or 365 nm) light. Oxygen response was governed by Langmuir law and its activation was insensitive to humidity. The mechanism of sensitization is analyzed together with other photo-induced effects—negative persistent photo-conduction and photo-induced hysteresis of field effect transistor characteristics. While the reduction of conductivity in air is persistent effect, the oxygen sensitization and enlargement of hysteresis take place only under the direct influence of light. It is concluded that the charge traps with differently adsorbed oxygen and water are involved in these phenomena.
Investigation of deep-level defects in Cu(In,Ga)Se2 thin films by a steady-state photocapacitance method
Authors: Hu Xiaobo , Sakurai Takeaki , Yamada Akimasa , Ishizuka Shogo , Niki Sigeru , Akimoto Katsuhiro
Published: October 2014

The properties of defect levels located 0.8 eV above the valence band in Cu(In1−x,Gax)Se2 thin films were investigated by a steady-state photocapacitance method. When illuminated by light with a photon energy of 0.8 eV at 60 K, a fast increase, followed by a slow increase, was observed in the photocapacitance transients of all samples. Upon being re-exposed, samples with a low bandgap energy showed a slow decrease in photocapacitance transients. These observations were interpreted using a configuration coordinate model assuming two states for the 0.8 eV defect: a stable state D and its metastable state D* with a large lattice relaxation. The difference in the evolution mechanisms of the photocapacitance transients was attributed to the difference in the optical transition of carriers between the two states of the 0.8 eV defect and the valence and conduction bands.
Power combination of two phase-locked high power microwave beams from a new coaxial microwave source based on dual beams
Authors: Li Yangmei , Zhang Xiaoping , Zhang Jiande , Dang Fangchao , Yan Xiaolu
Published: October 2014

The new coaxial high power microwave source based on dual beams has demonstrated two phase-locked output microwave beams generated by its two sub-sources. In order to achieve a single higher output power, we present a three-port waveguide-based power combiner to combine the two microwave beams. Particle-in-cell simulation results show that when the diode voltage is 675 kV and the guiding magnetic field is 0.8 T, a combined microwave with an average power of about 4.0 GW and a frequency of 9.74 GHz is generated; the corresponding power conversion efficiency is 29%. The combination effect of the combiner is further validated in the diode voltage range from 675 kV to 755 kV as well as in the pulse regime. The simulations indicate that the maximum surface axial electric field strength of the electrodynamic structure is 720 kV/cm, which is relatively low corresponding to an output power of 4.0 GW. The stable combined output suggests the probability of long-pulse operation for the combined source.
Enhanced Raman scattering assisted by ultrahigh order modes of the double metal cladding waveguide
Authors: Xu Tian , Huang Liming , Yin Cheng , Jin Yonglong , Fang Jinghuai , Huang Meizhen
Published: October 2014

Distinguished from the usual strategy to enhance the Raman scattering such as creating hot spots in the surface-enhanced Raman scattering, this paper takes a quite different approach based on the double metal cladding waveguide. The target analyte is located in the guiding layer of sub-millimeter scale, where several ultrahigh order modes with high intensity are simultaneously excited via a focused laser beam. The experimental setup is simple, and both simulation and experimental results confirm the enhancement mechanism of these oscillating modes. Other appealing features include the large detection area and the ability to excite guided modes via both polarizations. This scheme can be applied to large molecules detection and readily integrated with other Raman enhancement techniques.
The case for and against perennial forages in the Australian sheep–wheat zone: modelling livestock production, business risk and environmental interactions
Authors: Moore Andrew D.
Published: October 2014

Perennial forages have been proposed as a means of ameliorating both the summer–autumn feed gap and the risks posed by soil salinity and erosion in mixed farming areas of southern Australia. Whole-farm simulation analyses using the APSIM and GRAZPLAN models at nine locations across southern Australia have evaluated the likely trade-offs among expected profitability, financial risk, soil erosion risk, deep drainage and soil carbon change as annual pastures are converted to perennial pastures based on a C3 grass, a C4 grass or lucerne. Differences between perennial and annual feedbases in total pasture growth (median –11%, range –47% to +20%) and metabolisable energy supply from pasture (median +1%, range –48% to +52%) were diverse across locations and perennial species. At some locations, improvements in the pasture feedbase were counter-balanced by lower livestock intakes from crop stubbles. The modelled farming system with the highest profit included some perennial pasture at seven of the nine locations, but no one pasture species or land-use system predominated across all locations or producer risk attitudes. Local characteristics of the soils and farming systems are as important as broad climatic factors in determining how substituting perennial for annual pastures alters the trade-off between profitability and wind erosion risk. Further expanding permanent pastures into land currently used for crops only unequivocally reduced wind erosion risk at the four locations with Mediterranean climates. Lucerne grown in long rotations provided the best trade-off between mean gross margin and financial risk at Merriwagga and Temora. Permanent C3 or C4 perennial grass pastures separated from continuous cropping may simultaneously increase profits and reduce business and erosion risk at low-rainfall locations with Mediterranean climates, as long as they can be managed to persist. Managing pastures for greater nitrogen inputs could be considered as an erosion-abatement strategy.
Impact of initiatives to reduce public dental waiting lists in Queensland, Australia
Authors: Lalloo Ratilal , Kroon Jeroen
Published: October 2014

Information on public dental service waiting lists is available as part of the Queensland Government open data policy. Data were analysed for the period December 2012 to December 2013, to present the total number and percentage of people waiting for care and who have waited beyond the desirable period. Over the 1-year study period, the number of people on the waiting list decreased from 130 546 to 77 146, a difference of 40.9%. A decrease of 80.6% was found for those waiting beyond the desirable period for care. The largest decrease was for general care (44.9%). The initiatives to reduce the public dental waiting list appear to have been successful in significantly reducing the number of people waiting in general and especially those waiting beyond the desirable period. The initiatives to decrease waiting lists represent a downstream approach and are less likely to have any significant impact on the prevention of oral diseases. As waiting lists are reduced, more emphasis should be placed on upstream approaches such as health promotion, specific protection measures and targeting high-risk individuals for oral diseases.
Understanding shape entropy through local dense packing
Authors: van Anders Greg , Klotsa Daphne , Ahmed N. Khalid , Engel Michael , Glotzer Sharon C.
Published: October 2014

Significance

Many natural systems are structured by the ordering of repeated, distinct shapes. Understanding how this happens is difficult because shape affects structure in two ways. One is how the shape of a cell or nanoparticle, for example, affects its surface, chemical, or other intrinsic properties. The other is an emergent, entropic effect that arises from the geometry of the shape itself, which we term “shape entropy,” and is not well understood. In this paper, we determine how shape entropy affects structure. We quantify the mechanism and determine when shape entropy competes with intrinsic shape effects. Our results show that in a wide class of systems, shape affects bulk structure because crowded particles optimize their local packing.
Corporate Argumentation in Takeover Bids
Authors: Palmieri Rudi
Published: October 2014

This volume systematically investigates the role of argumentation in takeover bids. The announcement of these financial proposals triggers an argumentative situation, in which both the economic desirability and the social acceptability of the deal become argumentative issues for different classes of stakeholders (shareholders, employees, customers, etc.). The study focuses on the strategic maneuvers that corporate directors deploy in order to persuade their audiences while complying with precise regulatory requirements, designed to allow shareholders to make reasonable decisions.
A conceptual reframing of takeovers as an argumentative context brings to light the different argumentative situations of friendly and hostile bids. The argumentative strategies that corporate directors adopt in the two situations are identified and analyzed on the basis of a corpus of takeover documents referring to offers launched in the UK market between 2006 and 2010. The argumentative reconstruction focuses in particular on the inferential configuration of arguments, which is accomplished by means of the Argumentum Model of Topics (AMT). This kind of analysis enables capturing the inherently argumentative processes through which information becomes a relevant starting point for investment decisions.
A multifactorial corpus analysis of grammatical synonymy
Authors: Klavan Jane
Published: October 2014

In the present study, both monofactorial and multifactorial corpus methods are applied to the alternative use of the analytic adpositional construction and the synthetic case construction in present-day written Estonian. 600 examples from the fiction sub-corpora of written Estonian were annotated for 16 different (seven morphosyntactic and nine semantic) factors. In order to determine which factors are most influential in determining the choice between the two constructions, a logistic regression model was built to fit the data. The analysis confirmed the statistical influence of the following factors: lexical complexity, type of verb, word order, word class, and mobility. The results reported in this study align with previous research, which has shown that case affixes are used to express more abstract relations and adpositions more concrete ones.
A diachronic corpus-based multivariate analysis of “I think that” vs. “I think zero”
Authors: Shank Christopher , Plevoets Koen , Cuyckens Hubert
Published: October 2014

This corpus-driven study seeks to explain the choice between the zero complement and the that complement constructions, when occurring with the mental state predicate think. Previous studies have identified a range of factors that are argued to explain the alternation patterns. Such studies have also proposed that there is a diachronic drift towards zero complementation. Based on a sample of 9,720 think tokens, from both spoken and written corpora, from between 1560–2012, we test the hypothesis of diachronic change and the effect of eleven proposed factors on the constructional alternation. Using logistic regression, we demonstrate that, contrary to previous studies, there is in fact a diachronic decrease in zero complementation. Moreover, the study also demonstrates the importance of understanding the interaction of the various factors that explain the near-synonymous relation, including, especially, between the spoken and written modes.
Cluster analysis
Authors: Divjak Dagmar , Fieller Nick
Published: October 2014

Cluster analysis is an exploratory data analysis technique, encompassing a number of different algorithms and methods for sorting objects into groups. Cluster analysis requires the analyst to make choices about dissimilarity measures, grouping algorithms, etc., and these choices are difficult to make without an understanding of their theoretical implications and a very good understanding of the data. This chapter provides an introduction to the distance measures and clustering algorithms most commonly used for cluster analytic work. Different from Baayen (2008), Johnson (2008) and Gries (2009), its main aim is to equip the researcher with at least a basic understanding of what is happening behind the scenes when a dataset is explored with the help of a particular cluster analytic technique.
Logistic regression
Authors: Speelman Dirk
Published: October 2014

This text offers an introduction to binary logistic regression, a confirmatory technique for statistically modelling the effect of one or several predictors on a binary response variable. It is explained why logistic regression is exceptionally well suited for the comparison of near-synonyms in corpus data; the technique allows the researcher to identify the different factors that have an impact on the choice between near synonyms, and to tease apart their respective effects. Moreover, the technique is well suited to deal with the type of unbalanced data sets that are typical of Corpus Linguistics. First, we describe in which contexts logistic regression is applicable and we give examples of the types of research questions for which it is an appropriate tool. Next, we explain why and how logistic regression analysis is different from linear regression analysis and we illustrate how the output of logistic regression analysis can be interpreted, using the study of an alternation pattern in Dutch as our example. The R code used in the case study is explained in detail and an URL is given from which R code and data sets can be downloaded. Finally, suggestions for further reading are given.
The emergence of implicit meaning
Authors: Larrivée Pierre , Duffley Patrick
Published: October 2014

The purpose of this paper is to show how corpus data can contribute to assessing explicit hypotheses about natural language just as experimental protocols can. The particular hypotheses tested concern the source of generalised conversational implicatures with quantifiersome. Is the “some and not all” meaning ofsomea default interpretation of this item or a requirement of certain contexts? The defaultist approach (Levinson 2000, Chierchia 2004) would predict a preponderance of implicatures in the uses ofsome, whereas the contextualist approach (Sperber & Wilson 1986; Carston 1988, 2002) would predict that the implicature be found only with identifiable contextual triggers. The analysis of attested usage from the Bergen Corpus of London Teenage English (COLT) is shown to invalidate the former and to support the latter hypothesis. The workings of conversational implicatures are argued to be better understandable through corpus investigation than by recourse to decontextualized, self-fabricated, stock examples.
Variable satellite placement in spoken Dutch
Authors: Rys Jonah , De Cuypere Ludovic
Published: October 2014

This article presents a corpus study of the variable placement of adverbial satellites in spoken Dutch. It is widely contended that the relative order of satellites is motivated by three general principles: information status, length and the proximity principle. The proximity principle maintains that the placement of satellites is motivated by their semantic relationship with the sentence verb. We investigated the effect of the proximity principle on the relative placement of 8 different satellite classes based on a corpus sample of 202 combinations of two satellites retrieved from the Corpus of Spoken Dutch. The exact binomial test was used to evaluate the statistical significance of the observed orders. Our main results corroborate the hypothesis that the proximity principle influences satellite ordering. We also found, however, that the placement of certain satellite classes appeared very restricted, which suggests that the proximity principle does not play an active role in their placement.
AFLPs loci associated with polyembryonic maize using selective genotyping analysis
Authors: Cruz-Requena M. , Aguilar-González C.N. , Espinoza-Velázquez J. , Reyes-Valdés M.H. , Rodríguez-Herrera R.
Published: October 2014

Polyembryony is a trait widely distributed in nature which occurs in different plant species including maize. This trait has been studied at the genetic level with various molecular markers. In the present study we analyzed two monoembryonic and polyembryonic maize groups, derived from the F2population of a cross between plants from a high polyembryonic brachytic (BAP) population and a monoembryonic commercial variety (PUMA). Polymorphism was analyzed among and between these two F2maize groups with AFLPs (amplified fragment length polymorphisms). A total of 16 polymorphic bands were obtained, which were recorded as binary code (1 for band presence and 0 for absence). The data were analyzed using the InfoGen software. Contingency of AFLP against polyembryony was determined using the Chi square association. The results suggest a low genetic diversity between the F2groups. This result was corroborated with the Chi square test which indicated that two markers (13 and 15) may be related to polyembryony. The present study is the first report using segregating populations to identify more than one locus associated with PE in maize by marker techniques.
CLUH regulates mitochondrial biogenesis by binding mRNAs of nuclear-encoded mitochondrial proteins
Authors: Gao Jie , Schatton Désirée , Martinelli Paola , Hansen Henriette , Pla-Martin David , Barth Esther , Becker Christian , Altmueller Janine , Frommolt Peter , Sardiello Marco , Rugarli Elena I.
Published: October 2014

Mitochondrial function requires coordination of two genomes for protein biogenesis, efficient quality control mechanisms, and appropriate distribution of the organelles within the cell. How these mechanisms are integrated is currently not understood. Loss of the Clu1/CluA homologue (CLUH) gene led to clustering of the mitochondrial network by an unknown mechanism. We find that CLUH is coregulated both with genes encoding mitochondrial proteins and with genes involved in ribosomal biogenesis and translation. Our functional analysis identifies CLUH as a cytosolic messenger ribonucleic acid (RNA; mRNA)–binding protein. RNA immunoprecipitation experiments followed by next-generation sequencing demonstrated that CLUH specifically binds a subset of mRNAs encoding mitochondrial proteins. CLUH depletion decreased the levels of proteins translated by target transcripts and caused mitochondrial clustering. A fraction of CLUH colocalizes with tyrosinated tubulin and can be detected close to mitochondria, suggesting a role in regulating transport or translation of target transcripts close to mitochondria. Our data unravel a novel mechanism linking mitochondrial biogenesis and distribution.
LKB1 loss in melanoma disrupts directional migration toward extracellular matrix cues
Authors: Chan Keefe T. , Asokan Sreeja B. , King Samantha J. , Bo Tao , Dubose Evan S. , Liu Wenjin , Berginski Matthew E. , Simon Jeremy M. , Davis Ian J. , Gomez Shawn M. , Sharpless Norman E. , Bear James E.
Published: October 2014

Somatic inactivation of the serine/threonine kinase gene STK11/LKB1/PAR-4 occurs in a variety of cancers, including ∼10% of melanoma. However, how the loss of LKB1 activity facilitates melanoma invasion and metastasis remains poorly understood. In LKB1-null cells derived from an autochthonous murine model of melanoma with activated Kras and Lkb1 loss and matched reconstituted controls, we have investigated the mechanism by which LKB1 loss increases melanoma invasive motility. Using a microfluidic gradient chamber system and time-lapse microscopy, in this paper, we uncover a new function for LKB1 as a directional migration sensor of gradients of extracellular matrix (haptotaxis) but not soluble growth factor cues (chemotaxis). Systematic perturbation of known LKB1 effectors demonstrated that this response does not require canonical adenosine monophosphate–activated protein kinase (AMPK) activity but instead requires the activity of the AMPK-related microtubule affinity-regulating kinase (MARK)/PAR-1 family kinases. Inhibition of the LKB1–MARK pathway facilitated invasive motility, suggesting that loss of the ability to sense inhibitory matrix cues may promote melanoma invasion.
The cell biology of planar cell polarity
Authors: Devenport Danelle
Published: October 2014

Planar cell polarity (PCP) refers to the coordinated alignment of cell polarity across the tissue plane. Key to the establishment of PCP is asymmetric partitioning of cortical PCP components and intercellular communication to coordinate polarity between neighboring cells. Recent progress has been made toward understanding how protein transport, endocytosis, and intercellular interactions contribute to asymmetric PCP protein localization. Additionally, the functions of gradients and mechanical forces as global cues that bias PCP orientation are beginning to be elucidated. Together, these findings are shedding light on how global cues integrate with local cell interactions to organize cellular polarity at the tissue level.
Guangshuo Ou: New perspectives on Q cell biology
Authors: Sedwick Caitlin
Published: October 2014

Ou studies asymmetric stem cell division and differentiation in C. elegans Q neuroblasts.
Extracellular Ca2+ ions reduce NMDA receptor conductance and gating
Authors: Maki Bruce A. , Popescu Gabriela K.
Published: October 2014

Brief intracellular Ca2+ transients initiate signaling routines that direct cellular activities. Consequently, activation of Ca2+-permeable neurotransmitter-gated channels can both depolarize and initiate remodeling of the postsynaptic cell. In particular, the Ca2+ transient produced by NMDA receptors is essential to normal synaptic physiology, drives the development and plasticity of excitatory central synapses, and also mediates glutamate excitotoxicity. The amplitude and time course of the Ca2+ signal depends on the receptor’s conductance and gating kinetics; these properties are themselves influenced both directly and indirectly by fluctuations in the extracellular Ca2+ concentration. Here, we used electrophysiology and kinetic modeling to delineate the direct effects of extracellular Ca2+ on recombinant GluN1/GluN2A receptor conductance and gating. We report that, in addition to decreasing unitary conductance, Ca2+ also decreased channel open probability primarily by lengthening closed-channel periods. Using one-channel current recordings, we derive a kinetic model for GluN1/GluN2A receptors in physiological Ca2+ concentrations that accurately describes macroscopic channel behaviors. This model represents a practical instrument to probe the mechanisms that control the Ca2+ transients produced by NMDA receptors during both normal and aberrant synaptic signaling.
Using 2k + 2 bubble searches to find single nucleotide polymorphisms in k-mer graphs
Authors: Younsi Reda , MacLean Dan
Published: October 2014

Motivation: Single nucleotide polymorphism (SNP) discovery is an important preliminary for understanding genetic variation. With current sequencing methods, we can sample genomes comprehensively. SNPs are found by aligning sequence reads against longer assembled references. De Bruijn graphs are efficient data structures that can deal with the vast amount of data from modern technologies. Recent work has shown that the topology of these graphs captures enough information to allow the detection and characterization of genetic variants, offering an alternative to alignment-based methods. Such methods rely on depth-first walks of the graph to identify closing bifurcations. These methods are conservative or generate many false-positive results, particularly when traversing highly inter-connected (complex) regions of the graph or in regions of very high coverage.

Results: We devised an algorithm that calls SNPs in converted De Bruijn graphs by enumerating 2k + 2 cycles. We evaluated the accuracy of predicted SNPs by comparison with SNP lists from alignment-based methods. We tested accuracy of the SNP calling using sequence data from 16 ecotypes of Arabidopsis thaliana and found that accuracy was high. We found that SNP calling was even across the genome and genomic feature types. Using sequence-based attributes of the graph to train a decision tree allowed us to increase accuracy of SNP calls further. Together these results indicate that our algorithm is capable of finding SNPs accurately in complex sub-graphs and potentially comprehensively from whole genome graphs.

Availability and implementation: The source code for a C++ implementation of our algorithm is available under the GNU Public Licence v3 at: https://github.com/danmaclean/2kplus2. The datasets used in this study are available at the European Nucleotide Archive, reference ERP00565, http://www.ebi.ac.uk/ena/data/view/ERP000565

Contact:  dan.maclean@tsl.ac.uk

Supplementary information:  Supplementary Data are available at Bioinformatics online.
Mumps Serum Antibody Levels Before and After an Outbreak to Assess Infection and Immunity in Vaccinated Students
Authors: Gouma Sigrid , Schurink-van't Klooster Tessa M. , de Melker Hester E. , Kerkhof Jeroen , Smits Gaby P. , Hahné Susan J. M. , van Els Cécile A. C. M. , Boland Greet J. , Vossen Ann C. T. M. , Goswami Pulak R. , Koopmans Marion P. G. , van Binnendijk Rob S.
Published: October 2014

Background.  Since 2009, various mumps outbreaks have occurred in the Netherlands, affecting mostly young adults vaccinated against mumps. In this retrospective study, we estimated attack rates for symptomatic and asymptomatic mumps virus infection based on mumps-specific immunoglobulin (Ig)G concentrations in paired blood samples obtained before and after the mumps outbreaks, collected in 2 university cities. We aimed to identify a serological correlate of immune protection and risk factors for mumps virus infection.

Methods.  Mumps-specific IgG levels were measured by Luminex technology in paired pre- and post-outbreak samples from students from Leiden (n = 135) and Utrecht (n = 619). Persons with a 4-fold increase in mumps IgG concentrations or mumps IgG concentrations >1500 RU/mL were assumed to have had a mumps virus infection.

Results.  Attack rates for symptomatic and asymptomatic mumps virus infection were 2.0% and 3.8%, respectively. Pre-outbreak mumps-specific IgG concentrations were lower among cases than among noncases (P = .005) despite vaccination history, but no serological cutoff for immune protection could be established. Mumps among housemates was significantly associated with serological evidence for mumps virus infection (odds ratio, 7.25 [95% confidence interval, 3.20–16.40]; P < .001).

Conclusions.  Symptomatic and asymptomatic mumps virus infections in vaccinated persons can be identified by retrospective assessment of mumps-specific IgG antibodies in blood samples.
Assessment of Neutrophil Gelatinase-associated Lipocalin in the Brain-dead Organ Donor to Predict Immediate Graft Function in Kidney Recipients
Authors: Muller Laurent , Nicolas-Robin Armelle , Bastide Sophie , Martinez Orianne , Louart Guillaume , Colavolpe Jean-Christian , Vachiery Florence , Alonso Sandrine , Lefrant Jean-Yves , Riou Bruno ,   AzuRea Group
Published: October 2014

Background:

Delayed graft function is a major determinant of long-term renal allograft survival. Despite considerable efforts to improve donor selection and matching, incidence of delayed graft function remains close to 25%. As neutrophil gelatinase-associated lipocalin (NGAL) has been shown to predict acute renal failure, the authors tested the hypothesis that NGAL measurement in brain-dead donors predicts delayed graft function in kidney recipients.

Methods:

In a prospective, multicenter, observational study, serum NGAL was measured in donors at the time of transfer to operating room. The primary endpoint was the delayed graft function, defined as the need for renal replacement therapy during the first week posttransplantation.

Results:

Among 159 included brain-dead donors, 146 were analyzable leading to 243 renal transplantations. Of these, 56 (23%) needed renal replacement therapy. Donors’ NGAL values were similar in case of both delayed and normal graft function in recipients. The area under the receiver-operating curve for NGAL to predict the need for renal replacement therapy before day 8 was 0.50 (95% CI, 0.42 to 0.59). The area under curve for NGAL to predict failure to return to a normal graft function at day 8 was 0.51 (95% CI, 0.44 to 0.59). Using multivariate analysis, NGAL was not associated to the need for renal replacement therapy (odds ratio, 0.99; 95% CI, 0.98 to1.00) or failure to return to a normal graft function at day 8 (odds ratio, 1.00; 95% CI, 0.99 to 1.00).

Conclusion:

NGAL measurement in brain-dead donors at the time of recovery failed to predict delayed or normal graft function in kidney recipients.
A 22,403 marker composite genetic linkage map for cassava (Manihot esculentaCrantz) derived from ten populations
Authors:   International Cassava Genetic Map Consortium (ICGMC).
Published: October 2014

Cassava (Manihot esculentaCrantz) is a major staple crop in Africa, Asia, and South America, and its starchy roots provide nourishment for 800 million people worldwide. Although native to South America, cassava was brought to Africa approximately 400 years ago and is now widely cultivated across sub-Saharan Africa. The widespread use of clonal planting material, however, aids the spread of disease. Breeding for disease resistance and improved yield began in the 1920s and has accelerated in the last 45 years. To assist in the rapid identification of markers for pathogen resistance and crop traits, and to accelerate breeding programs, we generated a framework map forM. esculentaCrantz derived from reduced representation sequencing (genotyping-by-sequencing [GBS]). The composite 2,412 cM map integrates ten biparental maps (comprising 3,480 meioses) and organizes 22,403 genetic markers on 18 chromosomes, in agreement with the observed karyotype. The map anchors 71.9% of the draft genome assembly and 90.7% of the predicted protein-coding genes. The resulting chromosome-anchored genome sequence provides an essential framework for identification of trait markers and causal genes as well as genomics-enhanced breeding of this important crop.
Multicellularity makes somatic differentiation evolutionarily stable
Authors: Wahl Mary Elizabeth , Murray Andrew Wood
Published: October 2014

Many multicellular organisms produce two cell lineages: germ cells, whose descendants form the next generation, and somatic cells which support, protect, and disperse the germ cells. This distinction has evolved independently in dozens of multicellular taxa but is absent in unicellular species. We propose that unicellular, soma-producing populations are intrinsically susceptible to invasion by non-differentiating mutants which ultimately eradicate the differentiating lineage. We argue that multicellularity can prevent the victory of such mutants. To test this hypothesis, we engineer strains of the budding yeastSaccharomyces cerevisiaethat differ only in the presence or absence of multicellularity and somatic differentiation, permitting direct comparisons between organisms with different lifestyles. We find that non-differentiating mutants overtake unicellular populations but are outcompeted by multicellular differentiating strains, suggesting that multicellularity confers evolutionary stability to somatic differentiation.
Hedging weather risk for corn production in Northeastern China
Authors: Sun Baojing , Guo Changhao , Cornelis van Kooten G.
Published: October 2014

Purpose

– The paper analyzes the hedging efficiency of weather-indexed insurance for corn production in Northeast of China. The purpose of this paper is to identify the potential weather variables that impact corn yields and to analyze the efficiency of weather-indexed insurance under varying thresholds for payouts (strike values).

Design/methodology/approach

– Statistical relationships between climate variables and crop yields are used to construct weather-indexed insurance that enable a farmer to hedge against adverse precipitation outcomes. Mean root square loss is used to compare the efficiency of various weather products.

Findings

– Based on efficiency comparisons, it turns out that in some, but not all circumstances, cumulative rainfall (CR) insurance can be used to hedge weather risk. When CR explains one-third or more of the variation in corn yields, a hedge can offset the revenue loss caused by the corresponding weather risk; but when it explains much less of the yield variation, it is inefficient for hedgers to buy weather insurance. If CR explains variation in crop yields, it is increasingly efficient to employ CR-indexed insurance as strike values decline for put options or increase for call options.

Practical implications

– The paper provides a method for calculating the premium for an insurance product that provides a payout if CR in a growing season is too low.

Originality/value

– This research is important because it illustrates the potential benefits of using weather insurance as an agricultural risk management strategy in China.
Are agribusiness stocks an investor safe haven?
Authors: M. D’Antoni Jeremy , Dean Detre Joshua
Published: October 2014

Purpose

– The purpose of this paper is to determine how an index of agribusiness stocks performs relative to the S&P 500 particularly in times of recession.

Design/methodology/approach

– Using value-weighted indexes of agribusiness stocks, large cap US stocks, and copula estimation, the paper quantifies the correlation in potential investment portfolios. The information obtained from the copula estimated dependence measures and Value at Risk (VaR) allows to examine the diversification benefits of holding agribusiness stocks in the portfolio relative to the S&P 500.

Findings

– The results provide limited evidence that the addition of agribusiness stocks to a portfolio are able to provide significant diversification benefits to a portfolio of domestic equities, as represented by the S&P 500 index. The VaR analysis also indicates the risk of extreme losses remained relatively stable both across time and portfolio weightings.

Research limitations/implications

– While this research examines a broad-based agribusiness stock index, there exists a number of sub-assets classes within the analyzed index that should be analyzed to see if the offer benefits to investors. In addition, only stocks traded on US-based stock indexes are included in this analysis; as such, the authors would like to extend the research to have a more global approach.

Practical implications

– The findings suggest that investors who are looking to a broad-based agribusiness stock index to provide more diversification in their portfolio, may find it unattractive from a both a risk management and profit maximizing perspective. However, that does not mean that the agribusiness stock index might be an affective complement to a portfolio that contains multiple other assets classes.

Originality/value

– The issue of correlation convergence during financial crises is one of great concern to investors. To the authors’ knowledge, this is the first paper that uses copulas to evaluate the role of agribusiness stocks in an investor's portfolio.
Willingness to pay for agricultural crop insurance in the northern EU
Authors: Liesivaara Petri , Myyrä Sami
Published: October 2014

Purpose

– The purpose of this paper is to investigate the demand for crop insurance. Moreover, farmer willingness to pay (WTP) for crop insurance was derived. Factors affecting the demand were also examined in a country where crop insurance products are not currently available. Sensitivity analysis was conducted by studying the price-anchoring effect.

Design/methodology/approach

– Data from a choice experiment (CE) were analyzed with mixed logit models and the distribution of farmer WTP for crop insurance was derived. A split sample approach with varying premium vectors was used to analyze the price-anchoring effect.

Findings

– Demand was revealed for crop insurance products in Finland. The demand was higher among younger farmers and farms with more arable land. WTP for crop insurance products was very sensitive to the premium interval presented in the CE design.

Research limitations/implications

– The price-anchoring effect may disrupt the market development of crop insurance products, because insurance companies may take advantage of the lack of awareness among farmers of crop insurance pricing.

Practical implications

– The insurance product expected indemnity was a more important factor than the deductible in determining farmer WTP for crop insurance. Therefore, the 30 percent deductible level set for subsidized crop insurance products is not an obstacle for the development of such products in the EU.

Originality/value

– The study applied a well-known method (CE) to crop insurance in a country where these products are non-existent. The split sample approach was used to examine the price-anchoring effect on crop insurance.
Big assumptions for small samples in crop insurance
Authors: Elaine Hungerford Ashley , Goodwin Barry
Published: October 2014

Purpose

– The purpose of this paper is to investigate the effects of crop insurance premiums being determined by small samples of yields that are spatially correlated. If spatial autocorrelation and small sample size are not properly accounted for in premium ratings, the premium rates may inaccurately reflect the risk of a loss.

Design/methodology/approach

– The paper first examines the spatial autocorrelation among county-level yields of corn and soybeans in the Corn Belt by calculating Moran's I and the effective spatial degrees of freedom. After establishing the existence of spatial autocorrelation, copula models are used to estimate the joint distribution of corn yields and the joint distribution of soybean yields for a group of nine counties in Illinois. Bootstrap samples of the corn and soybean yields are generated to estimate copula models with the purpose of creating sampling distributions.

Findings

– The estimated bootstrap confidence intervals demonstrate that the copula parameter estimates and the premium rates derived from the parameter estimates can vary greatly. There is also evidence of bias in the parameter estimates.

Originality/value

– Although small samples will always be an issue in crop insurance ratings and assumptions must be made for the federal crop insurance program to operate at its current scale, this analysis sheds light on some of the issues caused by using small samples and will hopefully lead to the mitigation of these small sample issues.
Evaluation of aviation-based safety team training in a hospital in The Netherlands
Authors: F. de Korne Dirk , D.H. van Wijngaarden Jeroen , van Dyck Cathy , Francis Hiddema U. , S. Klazinga Niek
Published: October 2014

Purpose

– The purpose of this paper is to evaluate the implementation of a broad-scale team resource management (TRM) program on safety culture in a Dutch eye hospital, detailing the program’s content and procedures. Aviation-based TRM training is recognized as a useful approach to increase patient safety, but little is known about how it affects safety culture.

Design/methodology/approach

– Pre- and post-assessments of the hospitals’ safety culture was based on interviews with ophthalmologists, anesthesiologists, residents, nurses, and support staff. Interim observations were made at training sessions and in daily hospital practice.

Findings

– The program consisted of safety audits of processes and (team) activities, interactive classroom training sessions by aviation experts, a flight simulator session, and video recording of team activities with subsequent feedback. Medical professionals considered aviation experts inspiring role models and respected their non-hierarchical external perspective and focus on medical-technical issues. The post-assessment showed that ophthalmologists and other hospital staff had become increasingly aware of safety issues. The multidisciplinary approach promoted social (team) orientation that replaced the former functionally-oriented culture. The number of reported near-incidents greatly increased; the number of wrong-side surgeries stabilized to a minimum after an initial substantial reduction.

Research limitations/implications

– The study was observational and the hospital’s variety of efforts to improve safety culture prevented us from establishing a causal relation between improvement and any one specific intervention.

Originality/value

– Aviation-based TRM training can be a useful to stimulate safety culture in hospitals. Safety and quality improvements are not single treatment interventions but complex socio-technical interventions. A multidisciplinary system approach and focus on “team” instead of “profession” seems both necessary and difficult in hospital care.
Understanding patients’ behavioral intentions
Authors: Zarei Ehsan , Arab Mohammad , Mahmoud Ghazi Tabatabaei Seyed , Rashidian Arash , Rahimi forushani Abbas , Khabiri Roghayeh
Published: October 2014

Purpose

– In the ever-increasing competitive market of private hospital industry, creating a strong relationship with the customers that shapes patients’ loyalty has been considered a key factor in obtaining market share. The purpose of this paper is to test a model of customer loyalty among patients of private hospitals in Iran.

Design/methodology/approach

– This cross-sectional study was carried out in Tehran, the capital of the Islamic Republic of Iran in 2010. The study samples composed of 969 patients who were consecutively selected from eight private hospitals. The survey instrument was designed based on a review of the related literature and included 36 items. Data analysis was performed using structural equation modeling.

Findings

– For the service quality construct, three dimensions extracted: Process, interaction, and environment. Both process and interaction quality had significant effects on perceived value. Perceived value along with the process and interaction quality were the most important antecedents of patient overall satisfaction. The direct effect of the process and interaction quality on behavioral intentions was insignificant. Perceived value and patient overall satisfaction were the direct antecedents of patient behavioral intentions and the mediators between service quality and behavioral intentions. Environment quality of service delivery had no significant effect on perceived value, overall satisfaction, and behavioral intentions.

Originality/value

– Contrary to previous similar studies, the role of service quality was investigated not in a general sense, but in the form of three types of qualities including quality of environment, quality of process, and quality of interaction.
Optimal overbooking decision for hotel rooms revenue management
Authors: Phumchusri Naragain , Maneesophon Panaratch
Published: October 2014

Purpose

– This paper aims to develop overbooking models to determine the optimal number of overbooking for hotels having one and two different types of rooms.

Design/methodology/approach

– This paper presents mathematical modeling to find the optimal solutions of overbooking for stochastic cancellation.

Findings

– The authors prove that for hotels with only one type of room, there exists a closed form solution to guarantee the optimal number of overbooking, depending on the cost of walking customers to other hotels, the cost of unsold rooms and cancellation distribution observed in the past. For hotels with two types of room, they prove the convexity structure and identify equations to seek the number of overbooking for low-price and high-price rooms. The authors also provide key comparative statics on how model parameters impact the optimal decisions under different scenarios.

Practical implications

– Overbooking decision is one of important and complicated decision-makings, which is related directly to the yield of hotel revenue management. It is necessary for a hotel manager to observe cancellation pattern in the history to make a reliable decision. This paper presents a method that can help hotel manager make this decision in practice.

Originality/value

– This paper is one of the first articles in the hotel industry that considers the marginal cost for each room unsold caused by no shows and the marginal cost for each walking guest in a comprehensive perspective.