bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport properties of silicene-based ferromagnetic-insulator-superconductor junction
Authors: Vosoughi-nia Sakineh , Hajati Yaser , Rashedi Gholamreza
Published: July 2017

We study the tunneling conductance of a silicene-based ferromagnet/insulator/superconductor (FIS) junction by the use of the spin-dependent Dirac-Bogoliubov de-Gennes equation. We demonstrate that the conductance spectra are strongly affected by exchange energy h, Fermi energy EF, and external perpendicular electric field Ez. In the thin barrier limit of insulator silicene IS, the zero-bias charge conductance of the FIS silicene junction oscillates as a function of barrier strength χG. It is shown that the period of oscillations changes from π/2 to π corresponding to undoped and doped silicene. Remarkably, in contrast to that of the graphene FIS junction where the conductance only vanishes at the exchange energy h=EF, here due to the buckled structure of silicene, there is a transport gap region for the range of h values and the magnitude of such a gap region can be controlled by Ez. Moreover, it is found that by appropriate choice of h and Ez, it is possible to achieve a fully spin and valley-polarized charge conductance through the FIS silicene junction. This property suggests experimentally measuring the Fermi energy of silicene.
Age and growth of the banded guitarfish Zapteryx exasperata (Chondrichthyes: Trygonorrhinidae)
Authors: Cervantes-Gutiérrez Fabián , Tovar-Ávila Javier , Galván-Magaña Felipe
Published: July 2017

The banded guitarfish (Zapteryx exasperata) is the third most abundant ray species in the artisanal elasmobranch fishery of Baja California Sur, Mexico. However, there is no biological information about its age and growth parameters, limiting the application of some quantitative population assessment methods, such as demographic models. The aim of the present study was to estimate, for the first time, age and individual growth of Z. exasperata. Biometric data from 244 individuals and 236 vertebrae were analysed. The largest number of banded guitarfish in fishery landings was observed during April and August, with a female:male sex ratio of 1:1.8. The size range was 56.4–103-cm total length (TL) for females and 51.6–92cm TL for males, with females being significantly larger than males (P<0.05). The periodicity of the vertebral edge suggests that growth band pairs form annually. The estimated age structure was 5–22.6 years for females and 4–19.6 years for males, with significant differences between sexes (P<0.01). The goodness-of-fit of three models was evaluated. For the von Bertalanffy growth model, the parameters were as follows. For females: theoretical maximum length, L∞ = 100.71cm TL; growth coefficient, k = 0.144year–1; and theoretical age at length zero, t0 = –0.39years. For males: L∞ = 89.78cm TL; k = 0.174year–1; and t0 = –0.65years.
Introduction to peas and beans.
Authors: Biddle A. J.
Published: July 2017

This chapter introduces the most commonly grown large-seeded legumes used as food crops throughout the world. The species considered are: Pisum sativum, in the forms of dried peas (combining peas) and as fresh vegetables (vining peas or fresh market peas); Vicia faba, in the dry form as faba beans (or field beans) and the fresh form as broad beans; and Phaseolus vulgaris, in the dry form as dried beans and fresh as dwarf French or green (snap) beans. Their history, production and harvesting are discussed. Peas and beans have been domesticated and produced on a large scale in many parts of the world over a long period of time. There have been significant advances in production and harvesting techniques which have enabled largescale production both in area and quantity. In general, demand is increasing and peas and beans are being traded by major production countries worldwide.
Management of pests and diseases.
Authors: Biddle A. J.
Published: July 2017

This chapter deals with the management of pests (including insect pests and parasitic nematodes) and diseases (fungal, bacterial and viral) of peas, faba beans and Phaseolus beans. As all the described crop species are legumes, they can be hosts to the same organism even when there are slight differences in the races or strains, particularly with fungal pathogens, and so where there are commonalities these are identified. In each case, a description of the symptoms, effect on the crop, biology of the pest or disease and methods of monitoring and identifying the economic thresholds for justification of treatment are described. Infections of diseases or infestations of pests can be avoided by using a suitable crop rotation but although chemical control can be useful in many cases, effective application depends on the ability to define the optimum timing for applications of pesticides in order for them to work efficiently. With several pests and diseases, monitoring or forecasting systems have been developed and can be deployed in fields to give clear indications of the need to treat and the timing of such treatment. There is a growing requirement for the integration of management techniques to justify to customers the use of pesticides, and in many countries such practices are monitored by the end market. For several diseases that are seed borne in origin, the use of clean tested healthy seed is an important start for production and current development in breeding for resistance into some varieties of peas and beans is helping to reduce the risk of crop loss and disruption to factory throughput.
Taxonomy, botany and physiology.
Authors: Socias i Company R. , Ansón J. M. , Espiau M. T.
Published: July 2017

This chapter discusses the taxonomy of almond, including wild almond species, and describes the morphology of the root, canopy, bud and flower, fruit and kernel. Information is also given on the crop reproductive physiology, including flower initiation, flowering, pollination, fertilization, fruit development, and vegetative growth.
History of cultivation.
Authors: Gradziel T. M.
Published: July 2017

This chapter presents the prehitoric evidence, historical and cultural references, as well as the old and new world dissemination of almond cultivation. The modern cultivation of the crop, with emphasis on germplasm evaluation and cultivar and rootstock improvement, is also described, focusing on breeding programmes in Mediterranean Region, California (USA), Eastern Europe and Asia. The wide cultivation of almond in the often severe environments from Central Asia to the Mediterranean was possible largely because of the genetic and associated developmental/physiological diversity promoted by this typically self-incompatible yet interspecies fruitful genus.
Almond in the Southern Hemisphere.
Authors: Wirthensohn M. , Iannamico L.
Published: July 2017

This chapter discusses the history and development of almond production and cultivation in Australia, Argentina, Chile and South Africa, providing information on the cultivars in use. An analysis of the almond industry in some of these countries is given, including the advantages and disadvantages as well as the strengths, weaknesses, opportunities and threats (SWOT).
Pollen-style (in)compatibility: development of autogamous cultivars.
Authors: Socias i Company R.
Published: July 2017

This paper presents studies on almond self-incompatibility and self-compatibility done by pollination trials. The genetics and origin of self-compatibility are discussed, as well as the inbreeding effects on self-compatibility. The pollen component of self-incompatibility and the breeding of autogamous cultivars are described. Almond breeding programmes for self-compatibility were initiated with the expectation that self-compatibility would be transmitted to the offspring, as was the case. These programmes have been really successful and more than 20 cultivars have been released from the different breeding programmes. The Californian programmes have mostly introduced self-compatibility from peach, whereas the European programmes have used the Puglia cultivars as a source for self-compatibility. Self-compatibility maintains its importance in most almond breeding programmes and some of the new releases are being planted on a large scale, showing the real need for autogamous cultivars for efficient almond growing.
Rootstock development.
Authors: Rubio-Cabetas M. J. , Felipe A. J. , Reighard G. L.
Published: July 2017

This chapter deal with almond rootstock development. The most important traits of an almond rootstock are described, which are categorized into five groups: (i) nursery characteristics; (ii) graft compatibility; (iii) orchard characteristics; (iv) resistance to biotic (such as diseases, nematodes and insect pests) and abiotic (e.g. tolerance to heavy and calcareous soils and drought) factors; and (v) good sanitary status. The nursery production system determines if the rootstocks are to be seed or vegetative (asexually) propagated. In any case, any rootstock must fulfil all or most of the requirements from each group. The best rootstocks available at present for almond are presented, which include almond and peach seedlings, as well as clonal rootstocks. The almond rootstock breeding programmes in Europe and the USA are also mentioned.
Propagation techniques.
Authors: Rubio-Cabetas M. J. , Felipe A. J. , Bordas M.
Published: July 2017

This chapter descibes different propagation methods used in almond nurseries, which include seedling propagation, vegetative propagation (either by semi-hardwood or hardwood leafless cuttings), in vitro plant production, and scion propagation (T-budding, chip budding and regrafting).
Processing and industrialization.
Authors: Verdú A. , Izquierdo S. , Socias i Company R.
Published: July 2017

This article gives an overview about industrial preparation of almonds (reception, cracking and blanching); quality guidelines for almond reception (in-shell almonds and shelled almonds); and almond products (bitter almonds, appetizers, industrialization, turron, marzipan, cakes and pastries, ice cream, almond milk, gastronomy, cosmetics and pharmacy).
Hazardous terrain and tranquil waters
Authors: McGill Rebecca
Published: July 2017

Leadership development insights for nurse managers
When nutrition and allergy collide: the rise of anaphylaxis to plant foods
Authors: Skypala Isabel J.
Published: July 2017

Purpose of review

Interest in nutrition is increasing, but in the world of internet health gurus, whilst the nutritional benefits of fruits and vegetables are extolled, wheat is often vilified. This review will assess the positive nutritional effects of plant foods in relation to allergy prevention, the effectiveness of gluten-avoidance and the likelihood of anaphylaxis to fruits and vegetables.

Recent findings

Although the numbers of people who report gluten sensitivity is rising, hard evidence of mass sensitivity to gluten is scant. Also, the avoidance of wheat containing foods could lead to nutritional imbalance and effects on the gut microbiome. The evidence that fruits and vegetables have a protective effect on the development of allergy is inconsistent, although fruit juices may promote beneficial changes to gut microflora. Fruits and vegetables can cause severe allergic reactions, especially due to the presence of lipid transfer proteins, but this is not just a Mediterranean phenomenon, and not limited to peaches.

These findings emphasise the importance of a keeping an open mind about reported reactions to plant foods, to ensure the correct diagnosis is made and nutrition is optimised to prevent any adverse effects of avoidance on the gut microbiome.
Cortical Processing of Vocal and Nonvocal Sounds in Cochlear-Implanted Children: An Electrophysiological Study
Authors: Bakhos David , Galvin John , Roux Sylvie , Lescanne Emmanuel , Bruneau Nicole
Published: July 2017

Objectives:

For prelingually deaf children, cochlear implants (CIs) can restore auditory input to the auditory cortex and the ability to acquire spoken language. Language development is strongly intertwined with voice perception. The aim of this electrophysiological study was to investigate human voice processing using measures of cortical auditory evoked potentials (AEPs) in pediatric CI users.

Design:

Cortical AEPs were measured in 8 CI children (4 to 12 years old) with good auditory and language performance and 8 normal-hearing (NH) age-matched controls. The auditory stimuli were nonspeech vocal sounds (laughing, sighing, coughing) and environmental sounds (e.g., telephones, alarms, cars, bells, water, wind). Independent component analysis was used to minimize the CI artifact in cortical AEPs.

Results:

Fronto-temporal positivity to vocal sounds was found in NH children, with a significant effect in the 140 to 240 msec latency range. In CI children, there was a positive response to vocal sounds in the 170 to 250 msec latency range, with a more diffuse and anterior distribution than in the NH children.

Conclusions:

Cortical responses to vocal sounds were recorded in CI children. The topography and latency of response to voice differed from that of NH children. The results suggest that cortical reorganization for processing vocal sounds may occur in congenitally deaf children fitted with a CI.
Why do we fail to deliver evidence-based practice in critical care medicine?
Authors: Weiss Curtis H.
Published: July 2017

Purpose of review

The use of evidence-based practices in clinical practice is frequently inadequate. Recent research has uncovered many barriers to the implementation of evidence-based practices in critical care medicine. Using a comprehensive conceptual framework, this review identifies and classifies the barriers to implementation of several major critical care evidence-based practices.

Recent findings

The many barriers that have been recently identified can be classified into domains of the consolidated framework for implementation research (CFIR). Barriers to the management of patients with acute respiratory distress syndrome (ARDS) include ARDS under-recognition. Barriers to the use of the awakening and breathing coordination, delirium monitoring/management, and early exercise/mobility (ABCDE) bundle for mechanically ventilated patients and the sepsis bundle include patient-related, clinician-related, protocol-related, contextual-related, and intervention-related factors. Although these many barriers can be classified into all five CFIR domains (intervention, outer setting, inner setting, individuals, and process), most barriers fall within the individuals and inner setting domains.

There are many barriers to the implementation of evidence-based practice in critical care medicine. Systematically classifying these barriers allows implementation researchers and clinicians to design targeted implementation strategies, giving them the greatest chance of success in improving the use of evidence-based practice.
Macrophage complexity in human atherosclerosis: opportunities for treatment?
Authors: Biessen Erik A.L. , Wouters Kristiaan
Published: July 2017

Purpose of review

The pivotal role of macrophages in experimental atherosclerosis is firmly established, but their contribution to human disease is less well defined. In this review we have outlined the current insights on macrophage phenotypes and their presumed precursors, monocytes, in clinical atherosclerosis, and their association with disease progression. Moreover, we will assess major clinical modifiers of macrophage-mediated plaque inflammation and define the outstanding questions for further study.

Recent findings

Our survey indicates that macrophage accumulation and status in human plaques are linked with lesion progression and destabilization as well as with symptomatic coronary artery disease. Likewise, levels of their precursors, circulating monocytes were repeatedly seen to associate with atherosclerosis and to predict clinical outcome. Furthermore, the presence and phenotype of both macrophages and monocytes appears to be responsive to the traditional risk factors of atherosclerosis, including hypercholesterolemia, hypertension, and type 2 diabetes, and to treatment thereof, with clear repercussions on disease development.

Although plaque macrophages and their precursor cells do represent attractive targets for treating cardiovascular diseases, this therapeutic avenue requires much deeper understanding of the complexity of macrophage biology in human atherosclerosis than available at present.
Innate immunity against Zika virus
Authors: Lerat Vincent , Garcia Magali , Wehbe Michel , Beby-Defaux Agnès , Bodet Charles , Lévêque Nicolas
Published: July 2017

Zika virus (ZIKV) can be transmitted by the mosquito bite, through blood transfusion, organ transplantation and potentially urine or saliva. From its inoculation site, the virus will spread to various organs such as the central nervous system leading to neurological complications, particularly Guillain–Barré syndrome, or the fetus causing microcephaly. During the infection, ZIKV will have to cross multiple barriers according to the route of transmission and the infection site such as the skin, male and female genital mucosa or blood–brain and placental barriers. At these sites, ZIKV will establish an infection that the innate immune response will try to block before systemic spread occurs to the target organs. The aim of this review is to summarize the knowledge on the mechanisms of anti-ZIKV innate immunity, its characteristics at the different barriers encountered and tissues infected during the infection, and on the escape mechanisms developed by the virus to deal with it.
Life-Threatening and Fatal Adverse Drug Events in a Danish University Hospital
Authors: Tchijevitch Olga A. , Nielsen Lars Peter , Lisby Marianne
Published: July 2017

Objectives

Detection of adverse drug events (ADEs) in Danish hospitals relies on health care professionals’ incident reporting to a national database for adverse events, but the method is incomplete; thus, fatal and life-threatening ADEs may remain unrecognized.

The objectives of this study were to examine the occurrence of life-threatening and fatal ADEs in population of hospitalized patients with suspected adverse outcome and to compare these findings with the actual number of reported ADEs in the study period of 3 months.

Methods

Study was designed as a cross-sectional study of adult population, hospitalized for more than 24 hours, having an unplanned transfer to an intensive care unit (ICU), or having unexpected death. Medical records were retrospectively screened by the Global Trigger Tool. All positive triggers were assessed for ADEs by a clinical pharmacologist.

Results

Of the 26,176 patients admitted in the study period, 105 had an unplanned transfer to the ICU and 36 died unexpectedly. In total, 15 positive triggers were identified in 10 patients. Life-threatening ADEs accounted for 7.6% (8/105) of patients transferred to the ICU, and fatal ADEs constituted 5.5% (2/36) of the deceased patients. Life-threatening and fatal ADEs corresponded to an overall prevalence of 0.04% (10/26,176). Most ADEs were related to hemorrhages and respiratory problems. No serious or fatal ADEs were reported in the incident reporting system in the study period.

Conclusions

Ten life-threatening and fatal ADEs were uncovered as not reported in the incident reporting system. Further steps are needed for recognition and prevention of this patient safety challenge.
Determining whether a class of random graphs is consistent with an observed contact network
Authors: Nath Madhurima , Ren Yihui , Khorramzadeh Yasamin , Eubank Stephen
Published: July 2017

We demonstrate a general method to analyze the sensitivity of attack rate in a network model of infectious disease epidemiology to the structure of the network. We use Moore and Shannon’s “network reliability” statistic to measure the epidemic potential of a network. A number of networks are generated using exponential random graph models based on the properties of the contact network structure of one of the Add Health surveys. The expected number of infections on the original Add Health network is significantly different from that on any of the models derived from it. Because individual-level transmissibility and network structure are not separately identifiable parameters given population-level attack rate data it is possible to re-calibrate the transmissibility to fix this difference. However, the temporal behavior of the outbreak remains significantly different. Hence any estimates of the effectiveness of time dependent interventions on one network are unlikely to generalize to the other. Moreover, we show that in one case even a small perturbation to the network spoils the re-calibration. Unfortunately, the set of sufficient statistics for specifying a contact network model is not yet known. Until it is, estimates of the outcome of a dynamical process on a particular network obtained from simulations on a different network are not reliable.
Maternal Effects and Parent-Offspring Conflict
Authors: Kuijper Bram , Johnstone Rufus A.
Published: July 2017

Maternal effects can provide offspring with reliable information about the environment they are likely to experience, but also offer scope for maternal manipulation of young when interests diverge between parents and offspring. To predict the impact and outcome of parent-offspring conflict, we model the evolution of maternal effects on local adaptation of young. We find that parent-offspring conflict strongly influences the stability of maternal effects; moreover, the nature of the disagreement between parents and young predicts how conflict is resolved: when mothers favour less extreme mixtures of phenotypes relative to offspring (i.e., when mothers stand to gain by hedging their bets), mothers win the conflict by providing offspring with only limited amounts of information. When offspring favour overproduction of one and the same phenotype across all environments compared to mothers (e.g., when offspring favour a larger body size), neither side wins the conflict and signaling breaks down. Only when offspring favour less extreme mixtures relative to their mothers (the case we consider least likely), offspring win the conflict and obtain full information about the state of the environment. We conclude that a partial or complete breakdown of informative maternal effects will be the norm rather than the exception in the presence of parent-offspring conflict.
SPECTRE: a Suite of PhylogEnetiC Tools for Reticulate Evolution
Authors: Bastkowski Sarah , Mapleson Daniel , Spillner Andreas , Wu Taoyang , Balvočiūtė Monika , Moulton Vincent
Published: July 2017

Split-networks are a generalization of phylogenetic trees that have proven to be a powerful tool in phylogenetics. Various ways have been developed for computing such networks, including split-decomposition, NeighborNet, QNet and FlatNJ. Some of these approaches are implemented in the user-friendly SplitsTree software package. However, to give the user the option to adjust and extend these approaches and to facilitate their integration into analysis pipelines, there is a need for robust, open-source implementations of associated data structures and algorithms. Here we present SPECTRE, a readily available, open-source library of data structures written in Java, that comes complete with new implementations of several pre-published algorithms and a basic interactive graphical interface for visualizing planar split networks. SPECTRE also supports the use of longer running algorithms by providing command line interfaces, which can be executed on servers or in High Performance Computing (HPC) environments.

Availability

Full source code is available under the GPLv3 license at:https://github.com/maplesond/SPECTRE

SPECTRE’s core library is available from Maven Central at:https://mvnrepository.com/artifactuk.ac.uea.cmp.spectre/core

Documentation is available at:http://spectre-suite-of-phylogenetic-tools-for-reticulate-evolution.readthedocs.io/en/latest/

Contact

sarah.bastkowski@earlham.ac.uk

Supplementary Information (SI)

Supplementary information is available at Bioinformatics online.
Insects and incest: sib-mating tolerance in natural populations of a parasitoid wasp
Authors: Collet Marie , Amat Isabelle , Sauzet Sandrine , Auguste Alexandra , Fauvergue Xavier , Mouton Laurence , Desouhant Emmanuel
Published: July 2017

Sib-mating avoidance is a pervasive behaviour that likely evolves in species subject to inbreeding depression. Laboratory studies have provided elegant demonstrations of sib-mating avoidance, but small-scale bioassays often minimize the costs associated with mate finding and choice, which could lead to spurious findings.

We used the hymenopteran parasitoid waspVenturia canescensas a model organism, because previous laboratory studies revealed that sib-mating led to a 25% decrease in fertile offspring, and that sib-mating was partially avoided.

Our study consisted of a mate choice experiment in laboratory cages to determine if kin discrimination occurs in this species. We further performed a field study in which 86 wild-caught males, 155 wild-caught females and their 226 daughters daughters were genotyped at eighteen microsatellite loci. With these field data, we reconstructed the genotype of each female’s mate and estimated the relatedness of each mating pair.

Mate choice experiments confirmed that females are capable of discriminating kin. Time to mating depended on the frequency of female encounters with related and unrelated males. Contrary to previously published results, however, no sib-mating avoidance was detected. In the field, the effective rate of sib-mating did not differ from the probability that sibs encounter one other at random, which corroborates the absence of sib-mating avoidance. We also detected a weak but significant male bias in dispersal, which could reduce encounters between sibs.

Our results suggest that, despite kin discrimination,V. canescenstolerates sib-mating in the field. The weak male-biased dispersal cannot explain entirely this pattern. This raises the question as to why kin discrimination is maintained in this species. It further calls into question the idea that inbreeding depression occurs in most species with single-locus complementary sex determination.
The Generalized Quantitative Model of antibody homeostasis: maintenance of global antibody equilibrium by effector functions
Authors: Prechl József
Published: July 2017

The homeostasis of antibodies can be characterized as a balanced production, binding and elimination regulated by an interaction network, which controls B-cell development and selection. Recently we proposed a quantitative model to describe how the concentration and affinity of interacting partners generates a network.

Here we argue that this physical, quantitative approach can be extended for the interpretation of effector functions of antibodies. We define global antibody equilibrium as the zone of molar equivalence of free antibody and free antigen and immune complex concentrations and of dissociation constant of apparent affinity: [Ab]=[Ag]=[AbAg]=KD. This zone corresponds to the biologically relevant KDrange of reversible interactions. We show that thermodynamic and kinetic properties of antibody-antigen interactions correlate with immunological functions. The formation of stable, long-lived immune complexes correspond to a decrease of entropy and is a prerequisite for the generation of higher order complexes. As the energy of formation of complexes increases we observe a gradual shift from silent clearance to inflammatory reactions. These rules can also be applied to complement activation-related processes, linking innate and adaptive humoral responses. Affinity of the receptors mediating effector functions shows a corresponding range of affinities, allowing the continuous sampling of antibody-bound antigen over the complete range of concentrations. The generation of multivalent, multicomponent complexes triggers effector functions by cross-linking these receptors on effector cells with increasing enzymatic degradation potential.

Thus, antibody homeostasis is a thermodynamic system with complex network properties, nested into the host organism by proper immunoregulatory and effector pathways. Maintenance of global antibody equilibrium is achieved by innate qualitative signals modulating a quantitative adaptive immune system, which regulates molecular integrity of the host by tuning the degradation and recycling of molecules from silent removal to inflammatory elimination.
The ABC transporter Snu drives formation of the lipid-based inward and outward barrier in the skin ofDrosophila
Authors: Zuber Renata , Norum Michaela , Wang Yiwen , Oehl Kathrin , Accardi Davide , Bartozsewski Slawomir , Gehring Nicole , Berger Jürgen , Flötenmeyer Matthias , Moussian Bernard
Published: July 2017

Lipids in extracellular matrices (ECM) contribute to barrier function and stability of epithelial tissues such as the pulmonary alveoli and the skin. In insects, skin waterproofness depends on the outermost layer of the extracellular cuticle termed envelope that contains cuticulin, an unidentified water-repellent complex molecule composed of proteins, lipids and catecholamines. Based on live-imaging analyses of fruit fly larvae, we find that initially envelope units are assembled within vesicles harbouring the ABC transporter Snu and the extracellular protein Snsl. In a second step, the content of these vesicles is distributed to cuticular lipid-transporting nanotubes named pore canals and to the cuticle surface in dependence of Snu function. Consistently, the surface ofsnuandsnslmutant larvae is depleted from lipids and cuticulin. By consequence, these animals suffer uncontrolled water loss and penetration of xenobiotics. Our data allude to a two-step model of envelope i.e. barrier formation. The proposed mechanism in principle parallels the events occurring during differentiation of the lipid-based ECM by keratinocytes in the vertebrate skin suggesting establishment of analogous mechanisms of skin barrier formation in vertebrates and invertebrates.
Phase-merging enhanced harmonic generation free-electron laser with a normal modulator
Authors: Zhao Zhouyu , Li Heting , Jia Qika
Published: July 2017

A phase-merging enhanced harmonic generation free-electron laser (FEL) was proposed to increase the harmonic conversion efficiency of seeded FELs and promote the radiation wavelength towards the X-ray spectral region. However, this requires a specially designed transverse gradient undulator (TGU) as the modulator to couple the transverse and longitudinal phase space of the electron beam. In this paper, the generation of the phase-merging effect is explored using the natural field gradient of a normal planar undulator. In this method, a vertical dispersion on the electron beam is introduced and then the dispersed beam travels through a normal modulator in a vertical off-axis orbit where the vertical field gradient is selected properly in terms of the vertical dispersion strength and modulation amplitude. The phase-merging effect will be generated after passing through the dispersive chicane. Theoretical analysis and numerical simulations for a seeded soft X-ray FEL based on parameters of the Shanghai Soft X-ray FEL project are presented. Compared with a TGU modulator, using the natural gradient of a normal planar modulator has the distinct advantage that the gradient can be conveniently tuned in quite a large range by adjusting the beam orbit offset.
WIFIP: a web-based user interface for automated synchrotron beamlines
Authors: Sallaz-Damaz Yoann , Ferrer Jean-Luc
Published: July 2017

The beamline control software, through the associated graphical user interface (GUI), is the user access point to the experiment, interacting with synchrotron beamline components and providing automated routines. FIP, the French beamline for the Investigation of Proteins, is a highly automatized macromolecular crystallography (MX) beamline at the European Synchrotron Radiation Facility. On such a beamline, a significant number of users choose to control their experiment remotely. This is often performed with a limited bandwidth and from a large choice of computers and operating systems. Furthermore, this has to be possible in a rapidly evolving experimental environment, where new developments have to be easily integrated. To face these challenges, a light, platform-independent, control software and associated GUI are required. Here, WIFIP, a web-based user interface developed at FIP, is described. Further than being the present FIP control interface, WIFIP is also a proof of concept for future MX control software.
Anharmonic motionsversusdynamic disorder at the Mg ion from the charge densities in pyrope (Mg3Al2Si3O12) crystals at 30 K: six of one, half a dozen of the other
Authors: Destro Riccardo , Ruffo Riccardo , Roversi Pietro , Soave Raffaella , Loconte Laura , Lo Presti Leonardo
Published: July 2017

The possible occurrence of static/dynamic disorder at the Mg site in pyrope (Mg3Al2Si3O12), with or without anharmonic contribution to the thermal vibrations even at low temperatures, has been largely debated but conclusions were contrasting. Here a report is given on the experimental charge density distribution, ρEXP, of synthetic pyrope atT= 30 K, built through a Stewart multipolar expansion up tol= 5 and based on a very precise and accurate set of in-home measured single-crystal X-ray diffraction amplitudes with a maximum resolution of 0.44 Å. Local and integral topological properties of ρEXPare in substantial agreement with those of ρTHEO, the corresponding DFT-grade quantum charge density of an ideal pyrope crystal, and those derived from synchrotron investigations of chemical bonding in olivines. Relevant thermal atomic displacements, probably anharmonic in nature, clearly affect the whole structure down to 30 K. No significant (> 2.5σ) residual Fourier peaks are detectable from the ρEXPdistribution around Mg, after least-squares refinement of a multipole model with anharmonic thermal motion at the Mg site. Experimental findings were confirmed by a full analysis of normal vibration modes of the DFT-optimized structure of the perfect pyrope crystal. Mg undergoes wide displacements from its equilibrium position even at very low temperatures, as it is allocated in a ∼ 4.5 Å large dodecahedral cavity and involved in several soft phonon modes. Implications on the interplay among static/dynamic disorder of Mg and lattice vibrational degrees of freedom are discussed.
The role of conserved surface hydrophobic residues in the carbapenemase activity of the class D β-lactamases
Authors: Toth Marta , Smith Clyde A. , Antunes Nuno T. , Stewart Nichole K. , Maltz Lauren , Vakulenko Sergei B.
Published: July 2017

Carbapenem-hydrolyzing class D β-lactamases (CHDLs) produce resistance to the last-resort carbapenem antibiotics and render these drugs ineffective for the treatment of life-threatening infections. Here, it is shown that among the clinically important CHDLs, OXA-143 produces the highest levels of resistance to carbapenems and has the highest catalytic efficiency against these substrates. Structural data demonstrate that acylated carbapenems entirely fill the active site of CHDLs, leaving no space for water molecules, including the deacylating water. Since the entrance to the active site is obstructed by the acylated antibiotic, the deacylating water molecule must take a different route for entry. It is shown that in OXA-143 the movement of a conserved hydrophobic valine residue on the surface opens a channel to the active site of the enzyme, which would not only allow the exchange of water molecules between the active site and the milieu, but would also create extra space for a water molecule to position itself in the vicinity of the scissile bond of the acyl-enzyme intermediate to perform deacylation. Structural analysis of the OXA-23 carbapenemase shows that in this enzyme movement of the conserved leucine residue, juxtaposed to the valine on the molecular surface, creates a similar channel to the active site. These data strongly suggest that all CHDLs may employ a mechanism whereupon the movement of highly conserved valine or leucine residues would allow a water molecule to access the active site to promote deacylation. It is further demonstrated that the 6α-hydroxyethyl group of the bound carbapenem plays an important role in the stabilization of this channel. The recognition of a universal deacylation mechanism for CHDLs suggests a direction for the future development of inhibitors and novel antibiotics for these enzymes of utmost clinical importance.
Structural basis for the regulation of chemotaxis by MapZ in the presence of c-di-GMP
Authors: Zhu Yingxiao , Yuan Zenglin , Gu Lichuan
Published: July 2017

The bacterial second messenger cyclic diguanylate monophosphate (c-di-GMP) mediates multiple aspects of bacterial physiology through binding to various effectors. In some cases, these effectors are single-domain proteins which only contain a PilZ domain. It remains largely unknown how single-domain PilZ proteins function and regulate their downstream targets. Recently, a single-domain PilZ protein, MapZ (PA4608), was identified to inhibit the activity of the methyltransferase CheR1. Here, crystal structures of the C-terminal domain of CheR1 containing SAH and of CheR1 in complex with c-di-GMP-bound MapZ are reported. It was observed that the binding site of MapZ in CheR1 partially overlaps with the SAH/SAM-binding pocket. Consequently, binding of MapZ blocks SAH/SAM binding. This provides direct structural evidence on the mechanism of inhibition of CheR1 by MapZ in the presence of c-di-GMP.
Does executive ownership lead to excess target cash? The case of UK firms
Authors: Iona Alfonsina , Leonida Leone , Ventouri Alexia
Published: July 2017

Purpose

The aim of this paper is to investigate the dynamics between executive ownership and excess cash policy in the UK.

Design/methodology/approach

The authors identify firms adopting an excess policy using a joint criterion of high cash and cash higher than the target. Logit analysis is used to estimate the impact of executive ownership and other governance characteristics on the probability of adopting an excess cash policy.

Findings

The results suggest that, in the UK, the impact of the executive ownership on the probability of adopting an excess cash policy is non-monotonic, in line with the alignment-entrenchment hypothesis. The results are robust to different definitions of excess cash policy, to alternative specifications of the regression model, to different estimation frameworks and to alternative proxies of ownership concentration.

Research limitations/implications

The authors’ approach provides a new measure of the excess target cash for the firm. They show the need to identify an excess target cash policy not only by using an empirical criterion and a theoretical target level of cash, but also by capturing persistence in deviation from the target cash level. The authors’ measure of excess target cash calls into questions findings from previous studies. The authors’ approach can be used to explore whether excess cash holdings of UK firms and the impact of managerial ownership have changed from before the crisis to after the crisis.

Practical implications

The authors’ measure of excess target cash allows identifying in practice levels of cash which are abnormal with respect to an equilibrium level. UK firms should be cautious in using executive ownership as a corporate governance mechanism, as this may generate suboptimal cash holdings and suboptimal firm value. Excess cash policy might be driven not only by a poor corporate governance system, but also by the interplay between agency costs of managerial opportunism and cost of the external finance which further research could explore.

Originality/value

Actually, “how much cash is too much” is a question that has not been addressed by the literature. The authors address this question. Also, this amount of cash allows the authors to study the extent to which executive ownership contributes to explain the out-of-equilibrium persistency in the cash level.
The impact of board independency, CEO duality and CEO fixed compensation on M&A performance
Authors: Teti Emanuele , Dell’Acqua Alberto , Etro Leonardo , Volpe Michele
Published: July 2017

Purpose

This study aims to examine whether particular corporate governance mechanisms influence the performance of mergers and acquisitions.

Design/methodology/approach

Regression analyses investigating 1,596 recent acquisitions in the US market completed over the five-year period from 2009 to 2013 are performed.

Findings

The results show that board independency, CEO duality and level of CEO fixed compensation have an impact on the return of acquisitions. Moreover, the findings indicate that acquisitions significantly create value for bidders delivering a positive cumulative abnormal return upon announcement. Finally, also focusing on the 690 relative larger deals, there is a clear evidence of a positive influence of good corporate governance mechanisms over the quality of acquisitions completed.

Originality/value

To our knowledge, this is the first paper trying to identify corporate governance mechanisms related to the best acquisition decisions, by using specifically the three corporate governance variables (CEO duality, CEO fixed compensation and board independency).
Corporate governance reforms and bank performance: evidence from the Middle East and North Africa
Authors: Ghosh Saibal
Published: July 2017

Purpose

The purpose of the study is to understand the importance of corporate governance reforms for the Middle East and North Africa (MENA) country banks. To address this issue, the author combines the staggered timing of corporate governance reforms for banks across MENA countries with bank-level data for the period 2000-2012 and examine the impact on bank performance.

Design/methodology/approach

The author employs fixed effects regression within a difference-in-differences specification for the analysis.

Findings

The analysis suggests that not all governance characteristics are equally effective and some of these characteristics exert a more pronounced effect on bank performance as compared to others. These results also vary across oil-exporting and -importing nations and differ during the crisis. Besides, the authors find that improved operating efficiency and access to finance are the key channels through which governance improves bank performance.

Practical implications

Corporate governance reforms in the MENA countries need to be carefully tailored, taking into account the inherent economic characteristics of the country for it to exert durable impact. The challenge for policymakers is to find the right balance that can ensure maximum benefits for the banking sector, while minimizing the challenges involved in its implementation.

Originality/value

To the best of the authors’ knowledge, this is one of the earliest studies for MENA country banks to examine the interface between corporate governance reforms and bank performance, while controlling for the possible endogeneity of such reforms on performance.
Family firms, board structure and firm performance: evidence from top Indian firms
Authors: Bhatt R. Rathish , Bhattacharya Sujoy
Published: July 2017

Purpose

Given the prevalence of family-run businesses in India, this paper aims to empirically investigate the impact of family firms on the relationship between firm performance and board characteristics. The effectiveness of board characteristics such as independent directors, chairman independence, role duality, non-executive directors, board busyness, board size, board meetings and board attendance are studied in the Indian context.

Design/methodology/approach

The sample consists of top-listed firms in India for the period 2002 to 2012. Board index was constructed to capture the governance quality of the firm. The authors also study the relationship between board structure and firm performance by segregating the sample based on family management, family ownership and family representative directors. Random effects model was used for the regression analysis in the study.

Findings

The authors find a negative effect of board structure on firm performance in family firms compared to non-family firms. Contrary to the most Western literature, family management was not found to significantly affect firm performance as compared to that of professionally managed firms. In the subset analysis of family firms, higher proportion of family ownership and family representative directors did not show any significant impact on the firm performance. Having a higher proportion of independent directors, larger board size or an independent chairman does not appear to improve this insignificant relationship between family firms and firm performance. Also, in family firms, no significant difference in performance is noticed before and during recession period.

Originality/value

The study uses a self-defined corporate governance index to measure the governance parameters, specifically the board characteristics. The results documented in this study adds to the debate on the generalizability of the findings in Western governance studies in emerging markets like India with unique institutional development background.
Relationship between corporate governance and audit switching: Iranian evidence
Authors: Salehi Mahdi , Alinya Ali Asgar
Published: July 2017

Purpose

This paper aims to investigate the relationship between corporate governance and auditors switching of listed companies on the Tehran Stock Exchange.

Design/methodology/approach

To achieve the objectives of this study, 12 hypotheses developed which and tests the relationship between corporate governance and selecting and switching auditors in Iran during 2008-20014 by selecting 116 listed companies on the Tehran Stock Exchange. To test the hypotheses, the cross-sectional time-series nature of research variables data, panel analysis is used. Also, to investigate the relationship between independent and dependent variables in each year, the logistic regression is used.

Findings

The results of the study indicate that there is a weak relationship between corporate governance auditors switching. Therefore, it could be concluded that there are some other effective factors on which selecting and switching auditors in studied companies are more dependent.

Originality/value

The current study is almost the first study which has been conducted in Iran, so the results of the study may be beneficial to the Iranian conditions as well as other developing countries.