bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell-trappable fluorescent probes for endogenous hydrogen sulfide signaling and imaging H
2
O
2
-dependent H
2
S production
Authors: Lin Vivian S. , Lippert Alexander R. , Chang Christopher J.
Published: April 2013

Hydrogen sulfide (H
2
S) is a reactive small molecule generated in the body that can be beneficial or toxic owing to its potent redox activity. In living systems, disentangling the pathways responsible for H
2
S production and their physiological and pathological consequences remains a challenge in part due to a lack of methods for monitoring changes in endogenous H
2
S fluxes. The development of fluorescent probes with appropriate selectivity and sensitivity for monitoring production of H
2
S at biologically relevant signaling levels offers opportunities to explore its roles in a variety of systems. Here we report the design, synthesis, and application of a family of azide-based fluorescent H
2
S indicators, Sulfidefluor-4, Sulfidefluor-5 acetoxymethyl ester, and Sulfidefluor-7 acetoxymethyl ester, which offer the unique capability to image H
2
S generated at physiological signaling levels. These probes are optimized for cellular imaging and feature enhanced sensitivity and cellular retention compared with our previously reported molecules. In particular, Sulfidefluor-7 acetoxymethyl ester allows for direct, real-time visualization of endogenous H
2
S produced in live human umbilical vein endothelial cells upon stimulation with vascular endothelial growth factor (VEGF). Moreover, we show that H
2
S production is dependent on NADPH oxidase–derived hydrogen peroxide (H
2
O
2
), which attenuates VEGF receptor 2 phosphorylation and establishes a link for H
2
S/H
2
O
2
crosstalk.
Non-Fermi liquid regimes with and without quantum criticality in Ce

1−
x

Yb

x

CoIn
5
Authors: Hu Tao , Singh Yogesh P. , Shu Lei , Janoschek Marc , Dzero Maxim , Maple M. Brian , Almasan Carmen C.
Published: April 2013

One of the greatest challenges to Landau’s Fermi liquid theory—the standard theory of metals—is presented by complex materials with strong electronic correlations. In these materials, non-Fermi liquid transport and thermodynamic properties are often explained by the presence of a continuous quantum phase transition that happens at a quantum critical point (QCP). A QCP can be revealed by applying pressure, magnetic field, or changing the chemical composition. In the heavy-fermion compound CeCoIn
5
, the QCP is assumed to play a decisive role in defining the microscopic structure of both normal and superconducting states. However, the question of whether a QCP must be present in the material’s phase diagram to induce non-Fermi liquid behavior and trigger superconductivity remains open. Here, we show that the full suppression of the field-induced QCP in CeCoIn
5
by doping with Yb has surprisingly little impact on both unconventional superconductivity and non-Fermi liquid behavior. This implies that the non-Fermi liquid metallic behavior could be a new state of matter in its own right rather than a consequence of the underlying quantum phase transition.
Structure of the 26S proteasome with ATP-γS bound provides insights into the mechanism of nucleotide-dependent substrate translocation
Authors: Śledź Paweł , Unverdorben Pia , Beck Florian , Pfeifer Günter , Schweitzer Andreas , Förster Friedrich , Baumeister Wolfgang
Published: April 2013

The 26S proteasome is a 2.5-MDa, ATP-dependent multisubunit proteolytic complex that processively destroys proteins carrying a degradation signal. The proteasomal ATPase heterohexamer is a key module of the 19S regulatory particle; it unfolds substrates and translocates them into the 20S core particle where degradation takes place. We used cryoelectron microscopy single-particle analysis to obtain insights into the structural changes of 26S proteasome upon the binding and hydrolysis of ATP. The ATPase ring adopts at least two distinct helical staircase conformations dependent on the nucleotide state. The transition from the conformation observed in the presence of ATP to the predominant conformation in the presence of ATP-γS induces a sliding motion of the ATPase ring over the 20S core particle ring leading to an alignment of the translocation channels of the ATPase and the core particle gate, a conformational state likely to facilitate substrate translocation. Two types of intersubunit modules formed by the large ATPase domain of one ATPase subunit and the small ATPase domain of its neighbor exist. They resemble the contacts observed in the crystal structures of ClpX and proteasome-activating nucleotidase, respectively. The ClpX-like contacts are positioned consecutively and give rise to helical shape in the hexamer, whereas the proteasome-activating nucleotidase-like contact is required to close the ring. Conformational switching between these forms allows adopting different helical conformations in different nucleotide states. We postulate that ATP hydrolysis by the regulatory particle ATPase (Rpt) 5 subunit initiates a cascade of conformational changes, leading to pulling of the substrate, which is primarily executed by Rpt1, Rpt2, and Rpt6.
Child physical abuse and neglect in Kenya, Zambia and the Netherlands: A cross‐cultural comparison of prevalence, psychopathological sequelae and mediation by PTSS
Authors: Mbagaya Catherine , Oburu Paul , Bakermans‐Kranenburg Marian J.
Published: April 2013

This study compared the prevalence of self‐reported childhood physical abuse and neglect and the associated psychopathological sequelae among Kenyan, Zambian, and Dutch university students. In addition, we sought to find out the differentiated role of posttraumatic stress symptoms (PTSS) in mediating the associations between childhood maltreatment experiences and psychopathology symptoms. The sample consisted of 862 university students from Kenya (n = 375), Zambia (n = 182), and The Netherlands (n = 305) who completed the Personal and Relationships Profile (PRP). Results showed that physical abuse was highly prevalent in Kenya (59%) and Zambia (40%), and that neglect was even more prevalent than physical abuse in Zambia and The Netherlands at 59%, 54%, and 42% for the Kenyan, Zambian, and Dutch samples respectively. Neglect was associated with psychopathological symptoms in all three samples, whereas physical abuse was associated with psychopathological sequelae in the Kenyan and Zambian samples only. PTSS mediated the association between neglect and psychopathology symptoms in the Dutch sample and between physical abuse and psychopathology symptoms in the Dutch and Kenyan samples. We conclude that physical abuse and neglect are associated with psychopathology symptoms independently of country and cultural context. However, the pathways through which physical abuse and neglect may lead to psychopathological sequelae may be dependent on perceptions of specific parental behavior in different sociocultural contexts.
Cultural–geographical differences in the occurrence of child physical abuse? A meta‐analysis of global prevalence
Authors: Stoltenborgh Marije , Bakermans‐Kranenburg Marian J. , van IJzendoorn Marinus H. , Alink Lenneke R. A.
Published: April 2013

Our comprehensive meta‐analysis combined prevalence figures of child physical abuse reported in 111 studies, including 168 independent samples with a total of 9,698,801 participants. The overall estimated prevalence was 3/1000 for studies using informants and 226/1000 for studies using self‐report measures of child physical abuse, with no apparent gender differences. Methodological factors partly explained the vast variation of self‐reported prevalence rates in individual studies. The highest prevalence rates were found for studies using a broad definition of child physical abuse, studies measuring physical abuse over the longest period of 0–18 years, studies using college samples, studies in which adults served as respondents, and studies using more questions on physical abuse. Cultural–geographical factors did not seem to affect prevalence rates of physical abuse, which may be partly due to procedural factors. More crosscultural research on physical abuse is badly needed, especially in Africa and South America. We conclude that child physical abuse is a widespread, global phenomenon affecting the lives of millions of children all over the world, which is in sharp contrast with the United Nation's Convention on the Rights of the Child.
Child maltreatment as a global phenomenon: From trauma to prevention
Authors: Cyr Chantal , Michel Geneviève , Dumais Marilyne
Published: April 2013

Past studies have clearly showed the negative impact of neglect and abuse on child development at both the psychological and neurobiological levels. To date, many studies have focused on identifying risk and protective factors occurring at all levels of the ecology. However, more distal‐level variables, such as culture and ethnicity, have not been studied as much as those of more proximal levels; yet studies in Western countries have consistently found an overrepresentation of child maltreatment reports among ethnic minority groups. In this commentary, we reflect on a series of articles examining maltreatment from a crosscultural perspective and using samples of diverse countries. Taken together, studies in this special section document the terrible fact that maltreatment is a global phenomenon. Through a summary of these studies’ main findings and concerns, we highlight four key points that we believe are important to consider for future research and intervention efforts.
WHY DO COUPLES RELOCATE?
Authors: Melzer Silvia Maja
Published: April 2013

This paper examines the determinants of family migration from a post-socialist country, the former German Democratic Republic (today, the eastern part of reunified Germany), to a western country, West Germany. The paper seeks to answer the following questions: (1) How does the migration behavior of married and cohabitating men and women differ from that of individuals who live alone? (2) What factors influence family migration? (3) Are there gender-specific differences in the factors that influence migration? Hypotheses are derived from theories of gender roles, household economics, and bargaining to investigate the migration of individuals and families. Data from the Socio-Economic Panel Study covering the period 1992 to 2007 are analyzed using logistic hierarchical regression models. The results show that the male partner's education level is the most important determinant of migration, whereas the female partner's education is of secondary importance. The results generally support the predictions of gender role theory. Despite their egalitarian views and socialization in a socialist country, couples from East Germany exhibit a traditional orientation toward gender roles when making migration decisions.
THE EU: THE COMMUNITARIAN DEFICIT
Authors: Etzioni Amitai
Published: April 2013

The integration and centralization of the European Union (EU) has thus far proceeded without the level of community building necessary to sustain a full-fledged fiscal union. At issue is not the absence of a political union or a ‘democratic deficit’ but the very limited post-national community building, a communitarian deficit. The insufficient sharing of values and bonds – not the poor representative mechanisms – is a major cause of alienation from ‘Brussels’ and limits the normative commitment to make sacrifices for the common good. Major community building measures, in normative intensive areas, such as education and language must take place if the proposed steps towards significantly greater economic unity are to succeed. But, it is precisely these areas where community building is most absent. Hence it is likely that the current crisis will lead to a scaling back of the EU as administrative state rather than to ever higher levels of integration.
Cytoscape App Store
Authors: Lotia Samad , Montojo Jason , Dong Yue , Bader Gary D. , Pico Alexander R.
Published: April 2013

Summary: Cytoscape is an open source software tool for biological network visualization and analysis, which can be extended with independently developed apps. We launched the Cytoscape App Store to highlight the important features that apps add to Cytoscape, enable researchers to find and install apps they need and help developers promote their apps.

Availability: The App Store is available at http://apps.cytoscape.org.

Contact:  apico@gladstone.ucsf.edu
UPDtool: a tool for detection of iso- and heterodisomy in parent–child trios using SNP microarrays
Authors: Schroeder Christopher , Sturm Marc , Dufke Andreas , Mau-Holzmann Ulrike , Eggermann Thomas , Poths Sven , Riess Olaf , Bonin Michael
Published: April 2013

Summary: UPDtool is a computational tool for detection and classification of uniparental disomy (UPD) in trio SNP-microarray experiments. UPDs are rare events of chromosomal malsegregation and describe the condition of two homologous chromosomes or homologous chromosomal segments that were inherited from one parent. The occurrence of UPD can be of major clinical relevance. Though high-throughput molecular screening techniques are widely used, detection of UPDs and especially the subclassification remains complex. We developed UPDtool to detect and classify UPDs from SNP microarray data of parent–child trios. The algorithm was tested using five positive controls including both iso- and heterodisomic segmental UPDs and 30 trios from the HapMap project as negative controls. With UPDtool, we were able to correctly identify all occurrences of non-mosaic UPD within our positive controls, whereas no occurrence of UPD was found within our negative controls. In addition, the chromosomal breakage points could be determined more precisely than by microsatellite analysis. Our results were compared with both the gold standard, microsatellite analysis and SNPtrio, another program available for UPD detection. UPDtool is platform independent, light weight and flexible. Because of its simple input format, UPDtool may also be used with other high-throughput technologies (e.g. next-generation sequencing).

Availability and implementation: UPDtool executables, documentation and examples can be downloaded from http://www.uni-tuebingen.de/uni/thk/de/f-genomik-software.html.

Contact:  christopher.schroeder@med.uni-tuebingen.de

Supplementary information:  Supplementary data are available at Bioinformatics online.
Learning gene network structure from time laps cell imaging in RNAi Knock downs
Authors: Failmezger Henrik , Praveen Paurush , Tresch Achim , Fröhlich Holger
Published: April 2013

Motivation: As RNA interference is becoming a standard method for targeted gene perturbation, computational approaches to reverse engineer parts of biological networks based on measurable effects of RNAi become increasingly relevant. The vast majority of these methods use gene expression data, but little attention has been paid so far to other data types.

Results: Here we present a method, which can infer gene networks from high-dimensional phenotypic perturbation effects on single cells recorded by time-lapse microscopy. We use data from the Mitocheck project to extract multiple shape, intensity and texture features at each frame. Features from different cells and movies are then aligned along the cell cycle time. Subsequently we use Dynamic Nested Effects Models (dynoNEMs) to estimate parts of the network structure between perturbed genes via a Markov Chain Monte Carlo approach. Our simulation results indicate a high reconstruction quality of this method. A reconstruction based on 22 gene knock downs yielded a network, where all edges could be explained via the biological literature.

Availability: The implementation of dynoNEMs is part of the Bioconductor R-package nem.

Contact:  frohlich@bit.uni-bonn.de

Supplementary information:  Supplementary Data are available at Bioinformatics online.
Canards in piecewise-linear systems: explosions and super-explosions
Authors: Desroches Mathieu , Freire Emilio , Hogan S. John , Ponce Enrique , Thota Phanikrishna
Published: April 2013

We show that a planar slow–fast piecewise-linear (PWL) system with three zones admits limit cycles that share a lot of similarity with van der Pol canards, in particular an explosive growth. Using phase-space compactification, we show that these
quasi-canard
cycles are strongly related to a bifurcation at infinity. Furthermore, we investigate a limiting case in which we show the existence of a continuum of canard homoclinic connections that coexist for a single-parameter value and with amplitude ranging from an order of
ε
to an order of 1, a phenomenon truly associated with the non-smooth character of this system and which we call
super-explosion
.
Onset of centrifugal filtration convection: departure from thermal equilibrium
Authors: Saravanan S. , Brindha D.
Published: April 2013

This paper deals with convective instability in a fluid-saturated, rotating porous layer subject to alternating direction of the centrifugal body force, when the layer fails to exhibit thermal equilibrium. The Darcy model is used to describe the flow, and a two-field model is used to take care of the energy exchange. The normal mode approach of the linear theory and the energy approach of the nonlinear theory are used to find the stability characteristics. Unconditional and sharp nonlinear thresholds are found. The study brings out the failure of the linear theory in describing the instability in most parts of the parameter space of interest where possible subcritical instabilities may arise. The stability boundaries are presented graphically and it is found that the inter-phase heat transfer coefficient has a significant effect in the thermal non-equilibrium regime.
Genomic characterization of Sebokele virus 1 (SEBV1) reveals a new candidate species among the genus Parechovirus
Authors: Joffret M. L. , Bouchier C. , Grandadam M. , Zeller H. , Maufrais C. , Bourhy H. , Despres P. , Delpeyroux F. , Dacheux L.
Published: April 2013

We determined the genomic features and the taxonomic classification of Sebokele virus 1 (SEBV1), a previously unclassified arbovirus isolated in 1972 from rodents collected in Botambi, Central African Republic. The complete genome sequence was obtained using a deep sequencing approach (Illumina technology) and dedicated bioinformatics workflows for data analysis. Molecular analysis identified SEBV1 as a picornavirus, most closely related to Ljungan viruses of the genusParechovirus. The genome has a typical Ljungan virus-like organization, including the presence of two unrelated 2A protein motifs. Phylogenetic analysis confirmed that SEBV1 belongs to the parechovirus phylogroup and was most closely related to theLjungan virusspecies. However, it appeared clearly distinct from all members of this phylogroup, suggesting that it represents a novel species of the genusParechovirus.
Deletion of the Transcriptional Regulator cyAbrB2 Deregulates Primary Carbon Metabolism in Synechocystis sp. PCC 6803
Authors: Kaniya Yuki , Kizawa Ayumi , Miyagi Atsuko , Kawai-Yamada Maki , Uchimiya Hirofumi , Kaneko Yasuko , Nishiyama Yoshikata , Hihara Yukako
Published: April 2013

cyAbrB is a transcriptional regulator unique to and highly conserved among cyanobacterial species. A gene-disrupted mutant of cyabrB2 (sll0822) in Synechocystis sp. PCC 6803 exhibited severe growth inhibition and abnormal accumulation of glycogen granules within cells under photomixotrophic conditions. Within 6 h after the shift to photomixotrophic conditions, sodium bicarbonate-dependent oxygen evolution activity markedly declined in the ƊcyabrB2 mutant, but the decrease in methyl viologen-dependent electron transport activity was much smaller, indicating inhibition in carbon dioxide fixation. Decreases in the transcript levels of several genes related to sugar catabolism, carbon dioxide fixation, and nitrogen metabolism were also observed within 6 h. Metabolome analysis by capillary electrophoresis mass spectrometry revealed that several metabolites accumulated differently in the wild-type and mutant strains. For example, the amounts of pyruvate and 2-oxoglutarate (2OG) were significantly lower in the mutant than in the wild type, irrespective of trophic conditions. The growth rate of the ƊcyabrB2 mutant was restored to a level comparable to that under photoautotrophic conditions by addition of 2OG to the growth medium under photomixotrophic conditions. Activities of various metabolic processes, including carbon dioxide fixation, respiration, and nitrogen assimilation, seemed to be enhanced by 2OG addition. These observations suggest that cyAbrB2 is essential for the active transcription of genes related to carbon and nitrogen metabolism upon a shift to photomixotrophic conditions. Deletion of cyAbrB2 is likely to deregulate the partition of carbon between storage forms and soluble forms used for biosynthetic purposes. This disorder may cause inactivation of cellular metabolism, excess accumulation of reducing equivalents, and subsequent loss of viability under photomixotrophic conditions.
FiveN′-benzylidene-N-methylpyrazine-2-carbohydrazides
Authors: Gomes Ligia R. , Low John Nicolson , Rodrigues Ana S. M. C. , Wardell James L. , Lima Camillo H. da Silva , Souza Marcus V. N. de
Published: April 2013

The compoundsN′-benzylidene-N-methylpyrazine-2-carbohydrazide, C13H12N4O, (IIa),N′-(2-methoxybenzylidene)-N-methylpyrazine-2-carbohydrazide, C14H14N4O2, (IIb),N′-(4-cyanobenzylidene)-N-methylpyrazine-2-carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc),N-methyl-N′-(2-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IId), andN-methyl-N′-(4-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55–78°. These methylated pyrazine-2-carbohydrazides have supramolecular structures which are formed by weak C—H...O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π–π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0–6°.
Essential elements for recruitment and retention: Generation Y
Authors: Luscombe Jenna , Lewis Ioni , Biggs Herbert C.
Published: April 2013

Purpose

Generation Y (Gen Y) is the newest and largest generation entering the workforce. Gen Y may differ from previous generations in work‐related characteristics which may have recruitment and retention repercussions. Currently, limited theoretically‐based research exists regarding Gen Y's work expectations and goals in relation to undergraduate students and graduates. The aim of this paper is to attempt to address this gap in the research.

Design/methodology/approach

This study conducted a theoretically‐based investigation of the work expectations and goals of Generation Y and, in particular, student Gen Y versus working Gen Y individuals based within a framework incorporating both expectancy‐value and goal setting theories. n=398 provided useable data via an on‐line survey.

Findings

Overall, some support was found for predictions with career goals loading on a separate component to daily work expectations and significant differences between students and working Gen Y on career goals. No significant differences were found, however, between the two groups in daily work expectations.

Research limitations/implications

Future research studies may benefit from adopting a theoretical framework which assesses both daily work expectations and career goals. At a practical level, based on the findings, some examples are provided of the means by which organisations may draw upon daily work expectations and career goals of importance to Gen Y and, in doing so, influence the likelihood that a Gen Y individual will join and remain at their particular organisation.

Originality/value

This research has demonstrated the utility of adopting a sound theoretical framework in furthering understanding about the motivations which influence an organisations’ ability to recruit and retain Gen Y.
The influence of high performance work systems on voluntary turnover of new hires in US state governments
Authors: Selden Sally , Schimmoeller Lee , Thompson Reese
Published: April 2013

Purpose

This article aims to examine factors associated with new employee turnover in US state governments, where turnover is often highest in organizations. Building on existing studies of high performance work systems (HPWS) turnover, this article develops a set of hypotheses to explain new hire turnover.

Design/methodology/approach

The proposed model has been analyzed with a sample of 42 of the 50 US state governments.

Findings

Practices associated with HPWS influence turnover of new hires. State governments that operate centralized college recruiting programs, pay higher salaries, offer pay for performance incentives, award group bonuses, invest more in training, and allow job rotation lose significantly fewer new hires.

Research limitations/implications

This study is limited to specific variables collected in an online survey of states' central human resource departments. Future research may want to focus on other levels of government, include additional practices associated with HPWS, and examine measures of government performance.

Practical implications

This study stresses the importance of HPWS and how HRM practices impact new employees' decisions to stay or leave an organization. This information will provide an opportunity for actionable knowledge to be created that may help practitioners design and administer programs to reduce new hire turnover.

Originality/value

This study has extended a well‐developed body of knowledge on HPWS to government. Since most HPWS and turnover studies focus on turnover more broadly and since turnover is often highest among new hires, this research extends the HPWS framework to an important outcome, new hire quit rates.
The call center as a revolving door: a Philippine perspective
Authors: Regina M. Hechanova Ma.
Published: April 2013

Purpose

This study sought to explain the high turnover rates in Philippine call centers using a cultural lens. Specifically, the study looks at the phenomenon of work‐life conflict and its impact on turnover intent. It also examined the moderating role of perceived organization support on the relationship between work‐life conflict and turnover intent.

Design/methodology/approach

The study utilized a two‐phased, mixed‐method approach. In the first phase, qualitative data from 30 interviews were obtained to validate the existence of the constructs among Filipino call center agents. In the second phase, 991 surveys were administered to quantitatively test the hypothesized relationships between the study variables.

Findings

Results show that work‐life conflict predicts intent to leave over and beyond that explained by job satisfaction. Findings also show that organizational support moderates the relationship between work‐life conflict and intent to leave. The results also reveal the context‐specific sources of work‐life conflict: physical and psychological impact of work schedule, social isolation and lack of social support.

Research limitations/implications

The study focused on work‐life conflict and perceived organizational support. However, there are other variables that may be examined in future research such as personality, family, and organizational variables.

Practical implications

Beyond the traditional responses to the issue of work‐life conflict, the results suggest the importance of cultural nuanced responses to address work‐life conflict.

Social implications

Although outsourcing is a boon to the economy of developing countries, policies encouraging call centers need to be coupled with an understanding of the personal and social costs of call center work.

Originality/value

This study highlights the importance of considering culture in viewing management practices and their impact on workers' behavior and wellbeing. It calls attention to the unique experience of call centers in developing countries and the importance of developing work‐life interventions that are contextualized to local culture.
Agency conflicts and the demand for non‐audit services
Authors: Quick Reiner , Sattler Matthias , Wiemann Daniela
Published: April 2013

Purpose

The aim of the present paper is to examine the impact of agency costs on the demand for non‐audit services (NAS) in Germany.

Design/methodology/approach

This study uses data from German listed companies to test whether audit clients vary their purchases of NAS according to agency costs over time. The paper used multiple regressions and included ownership composition, performance‐based management compensation, and leverage as proxies for agency conflicts.

Findings

Overall, the hypothesis that agency costs influence the demand for NAS was not confirmed. None of our proxies for agency conflicts were significantly associated with the purchase of NAS. These findings remain stable when alternative NAS fee measures were applied.

Research limitations/implications

Findings cannot be generalised for smaller, private companies. Particularities of the German setting might have caused the insignificance of agency costs, but this cannot be tested statistically. The contrast between these insignificant results and the significant impact of agency costs on the demand for non‐audit services revealed by many previous studies, in particular from the US and the UK, raises important questions for future research.

Practical implications

This paper concerns management's perceptions on how stakeholders perceive the effect of NAS provision on auditor independence. Thus, its findings should be of interest to German, European and international regulators when evaluating the impact of the provision of NAS on independence in appearance.

Originality/value

This study is the first to provide evidence on the relationship between agency conflicts and the demand for non‐audit services from Germany and thus from a continental European country. Moreover, it provides evidence for periods after the introduction of stricter standards on the provision of non‐audit services. In addition, it applies a new proxy for agency costs (i.e. performance‐based management compensation).
M×N‐ary chaotic pulse‐width‐position modulation
Authors: Xuan Quyen Nguyen , Van Yem Vu , Manh Hoang Thang , Kyamakya Kyandoghere
Published: April 2013

Purpose

This paper presents and investigates a method named M×N‐ary chaotic pulse‐width‐position modulation (CPWPM) which is based on the combination of M‐ary chaotic pulse‐position modulation (CPPM) and N‐ary chaotic pulse‐width modulation (CPWM) in order to provide a better performance in noise‐affected environments as well as improve significantly bit rate.

Design/methodology/approach

Analysis of schemes for modulator and demodulator are presented in detail through describing the schemes of the individual methods and their combination. Theoretical evaluation of bit‐error rate (BER) performance in presence of additive white Gaussian noise (AWGN) is provided. Chaotic behavior with tent map in variation of modulation parameters is also investigated. In order to verify the theoretical analyses, numerical simulations are carried out and their results are reported.

Findings

Both evaluation and simulation results show that when the number of symbols increases, the bit rate is improved significantly but the BER performance is just slightly worse. This makes M×N‐ary CPWPM become an effective method for chaos‐based digital communication.

Originality/value

Although CPPM, CPWM and M‐ary modulation methods have been described in the literature separately, their combination is presented and investigated for the first time in this paper.
Determining the active and reactive power range in AC circuits
Authors: Kolev Lubomir
Published: April 2013

Purpose

The purpose of this paper is to suggest a polynomial complexity method for determining the range of the active and reactive power consumed in AC uncertain parameter circuits whose uncertain parameters are given as intervals.

Design/methodology/approach

First, the original problem is formulated as a corresponding interval quadratic range determination (IQRD) problem. Next, it is shown that the IQRD problem can be transformed equivalently into an interval linear range determination (ILRD) problem.

Findings

An efficient numerical method for solving the associated ILRD problem has been developed, capable of tackling the present active (or reactive) power range problem. It is based on the use of the outer solution y of an associated interval linear system defining the constraints in the ILRD problem.

Research limitations/implications

The method yields the exact active and reactive power range if the number of the components yi of y containing zero is relatively small (which is most often the case); otherwise, it provides tight outer bounds on the ranges sought.

Practical implications

The present method can be an alternative to the widely used Monte‐Carlo method since the former method provides exact (within rounding errors) results or tight outer approximations for lesser computation times.

Originality/value

To the best of the author's knowledge, the present paper suggests, for the first time, a simple interval analysis method of polynomial complexity for solving the problem considered which is inherently a NP‐hard problem (of exponential complexity).
Multi‐moment statistical characterization and nonlinear filtering of chaos
Authors: Kontorovich Valeri , Lovtchikova Zinaida
Published: April 2013

Purpose

The purpose of this paper is to provide the results of investigation of multi‐moment statistical characteristics of chaos and apply them to improve the accuracy of nonlinear algorithms for chaos filtering for real‐time applications.

Design/methodology/approach

The approach to find multi‐moment statistical properties of chaos‐multi‐moment cumulant (covariance) functions of higher order is a generalization of the previously proposed (by the authors) “degenerated cumulant equations” method. Those multi‐moment cumulants functions are applied in the generalization of the Stratonovich‐Kushner equations (SKE) for the optimum algorithm of nonlinear filtering of chaos as well as for synthesis of the quasi‐optimum algorithms.

Findings

Results are presented to investigate the multi‐moment statistical properties of chaos and formulate the theoretical background for synthesis of multi‐moment optimum and quasi‐optimum algorithms for nonlinear filtering of chaos with the improved accuracy in the presence of additive white noise.

Originality/value

The paper presents new theoretical results of the statistical description of chaos, previously partially reported only from experimental studies. A novel approach for chaos filtering is also presented. The proposed approach is dedicated to further improvement of the filtering accuracy for the case of low (less than one) SNR scenarios and is important for implementation in real‐time processing. As an important practical example, the new modified EKF algorithm is proposed with the rather opportunistic characteristics of the filtering fidelity together with algorithm complexity – practically the same as the “classic” one‐moment EKF algorithm.
MATLAB implementation of the complex power flow
Authors: Granelli Gianpietro , Montagna Mario
Published: April 2013

Purpose

The purpose of this work is that of providing the guidelines of an efficient implementation of power flow computations using the MATLAB computation environment.

Design/methodology/approach

The goal of obtaining high efficiency from MATLAB programs often proves elusive unless special care is taken in exploiting the vectorising capability of MATLAB programming. In the present paper the implementation of Newton‐Raphson power flow in MATLAB is examined with particular emphasis on the way of obtaining a vectorisable code capable of achieving effective numerical performance by exploiting its formulation in terms of complex variables.

Findings

Tests on actual networks with up to 1,300 buses are presented. They show that the complex power flow is as efficient as the best implementations of the Newton Raphson power flow using real variables, as long as the operations involved are reordered with the aim of exploiting the vectorisation capabilities of the MATLAB environment.

Originality/value

It is shown that improved numerical efficiency in the MATLAB can be obtained through its formulation in terms of complex variables. The complex Newton‐Raphson load flow, not very common in practical uses, is shown to have many desirable qualities from the point of view of MATLAB programming and is presented in detail.
The fuzzy correlation approach in operation of electrical distribution systems
Authors: Grigoras Gheorghe , Cartina Gheorghe
Published: April 2013

Purpose

The purpose of this paper is to introduce a method based on the fuzzy correlation for modelling of active and reactive powers from the substations of the electrical distribution systems, at the peak load.

Design/methodology/approach

Based on the correlation theory, the fuzzy models of the loads can be obtained using a new algorithm. If in the case of the principal/connection station there is sufficient database information for a good forecasting of the load, then for those substations where data are missing (there is no continuous monitoring or the measuring system can be broken for a while) the forecasting of the load can be performed using the correlation studies. The starting point of the algorithm is statistical analysis of the active and reactive curves of the substations and utilization of a fuzzy linear regression model. This can be made for different time windows (window 24 h, window 7 h, etc). The window 24 h can be used successfully to estimate the hourly load on any substation. The other time window (7 h) can be used in the peak load estimation of the substations, using the maximum value of the active power recorded in a reference substation.

Findings

The numerical data show that the fuzzy correlation models can be used with very good results for determination of the peak load corresponding distribution substations, and further with the state estimation of the system. In this study, the influence of the time window size is presented in detail, and the fuzzy correlation models for the peak loads from the distribution substations are obtained.

Originality/value

Starting from the correlation theory, a method of fuzzy modelling of active and reactive powers from the substations of an electrical distribution system is proposed.
Estimation of parameters in the state space model of stochastic RL electrical circuit
Authors: Farnoosh Rahman , Hajrajabi Arezoo
Published: April 2013

Purpose

The purpose of this paper is to consider the stochastic differential equation of the RL electrical circuit as the dynamic model of a state space system when the current in the circuit is hidden and corrupted by the measurement noise. Estimation of the corrupted current and the values of missing or unknown parameters (resistance, the observed current variance in the measurement model, the mean and variance of the current prior distribution) which are the main concern in electrical engineering is considered.

Design/methodology/approach

Optimal filtering is proposed for estimation of the hidden current from the noisy observations. Also, the problem of analyzing this model based on estimation of the unknown parameters is addressed from the likelihood‐based and Bayesian perspective.

Findings

Computational techniques for parameter estimation are carried out by the Maximum likelihood (ML) approach using Expectation‐Maximization type optimization and Bayesian Monte Carlo perspective using Metropolis‐Hastings scheme. The explicit formulas for the ML estimator are obtained and it is shown that the smoothers, the filters and the predictions for the current have the best confidence intervals, respectively. Some numerical simulation examples which are performed by R programming software are considered to show the efficiency and applicability of the proposed approaches. Results show an excellent estimation of the parameters based on these approaches.

Practical implications

Due to the fact that in an empirical situation of electrical engineering, observing the current in the circuit regardless of the measurement noise and knowing the exact value of the parameters are unrealistic assumptions, this paper can be used in various types of real time projects.

Originality/value

To the best of the authors' information, the problem of analyzing the state space model of RL electrical circuit has not been studied before. Furthermore, the estimation of the hidden current as the state of the system and estimation of the unknown parameters of the model via both ML and Bayesian approaches have been investigated for the first time in the present study.
Linking task and goal interdependence to quality service
Authors: Drach‐Zahavy Anat , Somech Anit
Published: April 2013

Purpose

With a twofold aim, the purpose of this paper is to focus on the service climate, including its antecedents, consequences, and a moderator. First, it examines whether task‐ and goal‐interdependent configuration facilitates the level of service climate; second, it tests the strength of the moderating role of service climate between service climate levels and service behavior.

Design/methodology/approach

Among 54 nursing units at six hospitals, the data were collected using multiple methods (surveys, observations, administrative data).

Findings

Mixed‐linear model analyses indicated that the joint effects of task and goal interdependence related significantly to service climate level. Service climate strength moderated the relationship of service climate level to quality service behavior.

Research limitations/implications

The research approach may diminish the generalizability of the research results. Further work should test the propositions in other research contexts.

Practical implications

Quality service behaviors and the service climate could be promoted through well‐designed task‐ and goal‐interdependence structures within units. Assimilating a service climate in units is not enough. To promote high quality service behaviors, managers must direct their efforts toward finding agreement among team members with regard with the importance of service in their unit.

Originality/value

The paper's findings offer empirical support to the persistent social interaction explanation of climate formation and point to the important role of interdependence for creating and maintaining service climate levels and promoting service behaviors in units.
Measuring consumer perceptions of online shopping convenience
Authors: Jiang Ling (Alice) , Yang Zhilin , Jun Minjoon
Published: April 2013

Purpose

The purpose of this paper is to identify the key convenience dimensions of online shopping, as convenience has been one of the principal motivations underlying customer inclinations to adopt online shopping.

Design/methodology/approach

The authors first employ in‐depth focus group interviews with online consumers to identify the attributes of online shopping convenience and then develop and validate an instrument of five key dimensions to measure online shopping convenience by analyzing data collected via a Web‐based questionnaire survey.

Findings

The five dimensions of online shopping convenience are: access, search, evaluation, transaction, and possession/post‐purchase convenience.

Practical implications

Online retailers can employ the five‐factor measurement instrument to assess the degree of customer perceived online shopping convenience. This instrument can assist managers in identifying and overcoming key obstacles to the delivery of a highly convenient online shopping service to customers, and also helps them enlarge their loyal customer base.

Originality/value

This study focuses on uncovering the key dimensions of convenience and their associated sub‐dimensions specific to the context of online shopping. Theoretically, the identified dimensions and their related sub‐items comprise a validated scale for measuring Web‐based service convenience and can serve as building blocks for further studies in e‐commerce customer relationship management.
A novel system for video news' sentiment analysis
Authors: Kechaou Zied , Wali Ali , Ben Ammar Mohamed , Karray Hichem , Alimi Adel M.
Published: April 2013

Purpose

Despite the actual prevalence of diverse types of multimedia information, research on video news is still in an early stage. Improving the accessibility of video news seems worth investigating, therefore, the purpose of this paper is to present a new combination mode of video news text clustering and selection. This method is useful for sorting out and classifying various types of news videos and media texts based on sentiment analysis.

Design/methodology/approach

A novel system is proposed, whereby video news are identified and categorized into good or bad ones via the authors' suggested Hidden Markov Model (HMM) and Support Vector Machine (SVM) hybrid learning method. Actually, an exploratory video news sentiment analysis case study, conducted on various news databases, has proven that the feature‐selection‐combining method, encompassing the Information Gain (IG), Mutual Information (MI) and CHI‐statistic (CHI), performs the best classification, which testifies and highlights the designed framework's value.

Findings

In fact, the system turns out to be applicable to several areas, especially video news, where annotation and personal perspectives affect the accuracy aspect.

Research limitations/implications

The present work shows the way for further research pertaining to the personal attitudes and the application of different linguistic techniques during the classification.

Originality/value

The achieved results are so promising, encouraging and satisfactory, that they highlight the originality and efficiency of the authors' approach as an effective tool enabling to secure an easy access to video news and multi‐media texts.
CSR communication:quo vadis?
Authors: Golob Urša , Podnar Klement , Elving Wim J. , Ellerup Nielsen Anne , Thomsen Christa , Schultz Friederike
Published: April 2013

Purpose

This paper aims to introduce the special issue on CSR communication attached to the First International CSR Communication Conference held in Amsterdam in October 2011. The aim of the introduction is also to review CSR communication papers published in scholarly journals in order to make a summary of the state of CSR communication knowledge.

Design/methodology/approach

The existing literature on CSR communication was approached via systematic review. with a combination of conventional and summative qualitative content analysis. The final dataset contained 90 papers from two main business and management databases, i.e. EBSCOhost and ProQuest.

Findings

Papers were coded into three main categories. The results show that the majority of the papers are concerned with disclosure themes. Considerably less salient are papers that fall under process‐oriented themes and the outcomes/consequences of CSR communications. The most important outlets for CSR communication‐related topics areJournal of Business EthicsandCorporate Communications: An International Journal.

Originality/value

This paper represents the first attempt to perform a systematic and comprehensive overview of CSR communication papers in scholarly journals. Its value is in making this rather vast and heterogeneous literature more visible and accessible to all CSR communication scholars.