bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance investigation of multi-chamber microbial fuel cell: An alternative approach for scale up system
Authors: Samsudeen N. , Sharma Amit , Radhakrishnan T. K. , Matheswaran Manickam
Published: July 2015

The performance of a multi-chamber microbial fuel cell (MFC) was investigated that consisting of four anodes and a cathode component separated by a membrane. The arrangements of the anode and cathode chambers were similar to four individual MFCs stack connected electrically in parallel fashion by sharing a cathode chamber. The multi-anode chamber MFC produced maximum open circuit potential of 720 ± 20 mV and the peak power density of 52.8 mW/m2 (162.5 mA/m2) at 100 Ω as normalized to the anode surface area. The effect of cathodic parameters such as electrode area, shapes, and catholyte concentrations was studied as factors affecting the power production. The wastewater concentration of 8720 mg COD/l was achieved the peak power density of 135.4 mW/m2 (368 mA/m2) using a graphite electrode with catholyte concentration of 100 mM potassium ferricyanide and 150 cm2 cathode electrode area. The results demonstrated that the proposed design may be an alternative approach to obtain high power generation and small space occupation for the scale-up MFC system.
New control strategy for fast-efficient maximum power point tracking without mechanical sensors applied to small wind energy conversion system
Authors: Daili Yacine , Gaubert Jean-Paul , Rahmani Lazhar
Published: July 2015

This paper proposes a new Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm for Small Wind Energy Conversion Systems to overcome the rapidity-efficiency trade-off and wrong behavior problems of the conventional P&O technique. The proposed algorithm works in two separate modes. The first mode is activated when the wind speed changes slowly. Under a rapid change of the wind speed, the second mode is switched to avoid the divergence of the system. The proposed algorithm requires only the measurement of the dc-link voltage and the dc current to realize the MPPT control, so no rotor speed measurement is needed, reducing the complexity of the overall system. The performance and the validity of the new MPPT algorithm have been proved by both simulation and experimental results.
Laser-ablated loading of solid target through foams of overcritical density
Authors: De Angelis R. , Consoli F. , Gus'kov S. Yu. , Rupasov A. A. , Andreoli P. , Cristofari G. , Di Giorgio G.
Published: July 2015

The main objective of the work is to study the conversion of the laser pulse energy into the energy of the hydrodynamic motion of matter in a solid target following the initial absorption of laser radiation in a layer of porous material. Results of experiments on plane massive aluminum targets, coated with a layer of porous plastic with density greater than the critical density of the plasma created, are presented. Experiments were carried out on the laser installation ABC of the Research Center ENEA-Frascati; the targets were irradiated by a beam of the fundamental harmonic of Nd-laser radiation with an energy of about 50 kJ, intensity of 1013 W/cm2, and 3 ns duration. The experimental method consisted in measuring the volume of the craters created on the aluminum surface behind various thicknesses and densities of the porous absorber of laser radiation. On the basis of these measurements and of an advanced analytical model, quantitative conclusions are made on how the efficiency of laser energy transfer to the solid part of the target (laser-ablated loading) depends on thickness and density of the porous absorber.
A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures
Authors: Pristavu G. , Brezeanu G. , Badila M. , Pascu R. , Danila M. , Godignon P.
Published: July 2015

Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (ΦBn,l) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured IF–VF–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni2Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni2Si/4H-SiC Schottky contacts.
Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices
Authors: Pal Atindra Nath , Müller Susanne , Ihn Thomas , Ensslin Klaus , Tschirky Thomas , Charpentier Christophe , Wegscheider Werner
Published: July 2015

We report the electronic characterization of mesoscopic Hall bar devices fabricated from coupled InAs/GaSb quantum wells sandwiched between AlSb barriers, an emerging candidate for two-dimensional topological insulators. The electronic width of the etched structures was determined from the low field magneto-resistance peak, a characteristic signature of partially diffusive boundary scattering in the ballistic limit. In case of dry-etching the electronic width was found to decrease with electron density. In contrast, for wet etched devices it stayed constant with density. Moreover, the boundary scattering was found to be more specular for wet-etched devices, which may be relevant for studying topological edge states.
Patterns of knowledge use in ‘low-tech’ industries
Authors: Hirsch-Kreinsen Hartmut
Published: July 2015

The innovativeness of low- and medium-technology (LMT) manufacturing firms in advanced economies has been the research focus of a growing body of literature since the beginning of the last decade. This paper reviews the main research findings and highlights the largely unresolved problem in LMT research of the contradiction between the presumed homogeneity of LMT sectors because of the formal category of ‘low R&D intensity’, and the heterogeneity of the same firms in LMT sectors. To overcome this problem, the paper proposes an empirical taxonomy of innovative LMT firms based on the dimension of knowledge. To sketch out this knowledge-oriented taxonomy, the paper uses the concept of the ‘distributed knowledge base’. In this approach, four different patterns of knowledge use in LMT firms can be identified. This conceptual perspective has consequences for understanding the sources and directions of innovation strategies in LMT firms and the perspectives of LMT sectors pertaining in advanced economies, such as the EU. Additionally, specific recommendations on innovation policy can be inferred from these considerations that go beyond the current state of the art. Overall, this paper sums up some of the findings of past low-tech research, and reinterprets its central findings.
Frequency, characteristics, and perceived functions of emotional future thinking in daily life
Authors: Barsics Catherine , Van der Linden Martial , D'Argembeau Arnaud
Published: July 2015

While many thoughts and mental images that people form about their personal future refer to emotionally significant events, there is still little empirical data on the frequency and nature of emotional future-oriented thoughts (EmoFTs) that occur in natural settings. In the present study, participants recorded EmoFTs occurring in daily life and rated their characteristics, emotional properties, and perceived functions. The results showed that EmoFTs are frequent, occur in various contexts, and are perceived to fulfil important functions, mostly related to goal pursuit and emotion regulation. When distinguishing between anticipatory and anticipated emotions (i.e., emotions experienced in the present versus emotions expected to occur in the future), a positivity bias in the frequency of EmoFTs was found to be restricted to anticipated emotions. The representational format and perceived function of EmoFTs varied according to their affective valence, and the intensity of anticipatory and anticipated emotions were influenced by the personal importance and amount of visual imagery of EmoFTs. Mood states preceding EmoFTs influenced their emotional components, which, in turn, impacted ensuing mood states. Overall, these findings shed further light on the emotional properties of future-oriented thoughts that are experienced in daily life.
The chemical structure of the ZnO/SiC heterointerface as revealed by electron spectroscopies
Authors: Mu Rui , Steigert Alexander , Lin Nanying , Wilks Regan , Bär Marcus , Zhang Yufeng
Published: July 2015

ZnO layers were deposited on 6H-SiC single crystalline wafers by radio frequency magnetron sputtering. The chemical structure of the ZnO/SiC interface was studied by x-ray photoelectron and x-ray excited Auger electron spectroscopy. A complex chemical structure, involving not only silicon–carbon and zinc–oxygen bonds but also silicon–oxygen and zinc–silicon–oxygen bonds was revealed to form at the ZnO/SiC interface. Based on the comparison with the presumably inert (i.e. chemically abrupt) ZnO/Mo interface, it was concluded that a willemite-like zinc silicate (i.e. Zn2SiO4) interface species develops between ZnO and SiC. The presence of this species at the ZnO/SiC interface will affect the electronic structure of the heterojunction and thus needs to be considered for device optimization.
Functional classification of CATH superfamilies: a domain-based approach for protein function annotation
Authors: Das Sayoni , Lee David , Sillitoe Ian , Dawson Natalie L. , Lees Jonathan G. , Orengo Christine A.
Published: July 2015

Motivation: Computational approaches that can predict protein functions are essential to bridge the widening function annotation gap especially since <1.0% of all proteins in UniProtKB have been experimentally characterized. We present a domain-based method for protein function classification and prediction of functional sites that exploits functional sub-classification of CATH superfamilies. The superfamilies are sub-classified into functional families (FunFams) using a hierarchical clustering algorithm supervised by a new classification method, FunFHMMer.

Results: FunFHMMer generates more functionally coherent groupings of protein sequences than other domain-based protein classifications. This has been validated using known functional information. The conserved positions predicted by the FunFams are also found to be enriched in known functional residues. Moreover, the functional annotations provided by the FunFams are found to be more precise than other domain-based resources. FunFHMMer currently identifies 110 439 FunFams in 2735 superfamilies which can be used to functionally annotate > 16 million domain sequences.

Availability and implementation: All FunFam annotation data are made available through the CATH webpages (http://www.cathdb.info). The FunFHMMer webserver (http://www.cathdb.info/search/by_funfhmmer) allows users to submit query sequences for assignment to a CATH FunFam.

Contact:  sayoni.das.12@ucl.ac.uk

Supplementary information:  Supplementary data are available at Bioinformatics online.
Error filtering, pair assembly and error correction for next-generation sequencing reads
Authors: Edgar Robert C. , Flyvbjerg Henrik
Published: July 2015

Motivation: Next-generation sequencing produces vast amounts of data with errors that are difficult to distinguish from true biological variation when coverage is low.

Results: We demonstrate large reductions in error frequencies, especially for high-error-rate reads, by three independent means: (i) filtering reads according to their expected number of errors, (ii) assembling overlapping read pairs and (iii) for amplicon reads, by exploiting unique sequence abundances to perform error correction. We also show that most published paired read assemblers calculate incorrect posterior quality scores.

Availability and implementation: These methods are implemented in the USEARCH package. Binaries are freely available at http://drive5.com/usearch.

Contact:  robert@drive5.com

Supplementary information: Supplementary data are available at Bioinformatics online.
The center for causal discovery of biomedical knowledge from big data
Authors: Cooper Gregory F , Bahar Ivet , Becich Michael J , Benos Panayiotis V , Berg Jeremy , Espino Jessi , Glymour Clark , Jacobson Rebecca Crowley , Kienholz Michelle , Lee Adrian V , Lu Xinghua , Scheines Richard ,   and the Center for Causal Discovery team
Published: July 2015

The Big Data to Knowledge (BD2K) Center for Causal Discovery is developing and disseminating an integrated set of open source tools that support causal modeling and discovery of biomedical knowledge from large and complex biomedical datasets. The Center integrates teams of biomedical and data scientists focused on the refinement of existing and the development of new constraint-based and Bayesian algorithms based on causal Bayesian networks, the optimization of software for efficient operation in a supercomputing environment, and the testing of algorithms and software developed using real data from 3 representative driving biomedical projects: cancer driver mutations, lung disease, and the functional connectome of the human brain. Associated training activities provide both biomedical and data scientists with the knowledge and skills needed to apply and extend these tools. Collaborative activities with the BD2K Consortium further advance causal discovery tools and integrate tools and resources developed by other centers.
Learned Style and Learned Styles
Authors: Chapin Keith
Published: July 2015

Eighteenth-century writers on music recognized a spectrum of learned styles. These included not only the imitative counterpoint characteristic of the fugue and the species counterpoint associated witha cappellapolyphony, but also a broad range of other styles, such as strict style, church style, orstile antico, transmitted from specialist to specialist over many decades and even centuries. The topic of the learned style, however, was a special formation or intensification of texture that occurred within the norms of late eighteenth-century phrasing, harmony, and texture. The tension between learned styles (each grounded in certain genre traditions) and learned style (the versatile and itinerant topic) informs not only the various manifestations of the learned style, which can be used for various formal purposes, but also its signification, which springs from the concerns of order and tradition that accompanied the transmission of learned styles from generation to generation.
Topics and Formal Functions
Authors: Caplin William
Published: July 2015

This chapter examines the relationship of the lament topic to various form-functional contexts. After explaining that this topic is inextricably linked with a schema defined essentially by its bass voice, the study considers how the intrinsically sequential harmonic content of the schema lends itself well to expressing the formal sense of “being in the middle.” It further demonstrates that the schema can also participate in creating a formal ending, a cadence, and can even be used in an initiating formal context, which may engender the perception of a “formal dissonance,” a conflict between intrinsic and contextual functionality. The pervasive descending bass line of the lament schema, while appropriate for baroque compositional practice, jars somewhat with classical practice, such that the lament topic becomes a touchstone for highlighting stylistic differences among earlier and later works within the eighteenth century.
Expectation, Musical Topics, and the Problem of Affective Differentiation
Authors: Margulis Elizabeth Hellmuth
Published: July 2015

Since Leonard Meyer (1956), music theorists have looked to expectation as a primary generator of musical affect. Yet, expectation and its complement—surprise—do not explain affective differentiation of the experience of listening to music. This study looks to a different tradition in music theory—that of musical topics—for a possible explanation. Listeners heard excerpts representing one of four musical topics in a normative and surprising version, where a general pause had been inserted before the cadence. Listeners continuously rated the excerpts as they progressed along one of four different affective dimensions. The hypothesis was that surprise—the general pause—would elevate perceptions of particular affective dimensions only in particular topical contexts. Musical topics, in other words, might function as a lens through which surprise is transformed into distinct phenomenological experiences.
Topics and Opera Buffa
Authors: Hunter Mary
Published: July 2015

Opera buffa is cited as the source for the topical variety of classical style instrumental music. It is also cited as a topic within instrumental music. This essay argues, with examples from works by Haydn, Mozart, Galuppi, Cimarosa, and Martín y Soler, that musical devices of opera buffa were not on the whole exported to instrumental music but rather were translated to the subtler and more refined instrumental idiom. When opera buffa is identified as a topic in instrumental music, it is more often the presumed gestural world of the comic stage that is evoked than the actual musical devices most characteristic of the genre. And when we study topics in opera—either buffa or seria—it is worth taking into account that they have the capacity not only redundantly to confirm verbal and visual cues, but also to complicate them by suggesting irony or parody, among other things.
Stressful Life Events in Children With Functional Defecation Disorders
Authors: Philips Elise M. , Peeters Babette , Teeuw Arianne H. , Leenders Arnold G.E. , Boluyt Nicole , Brilleslijper‐Kater Sonja N. , Benninga Marc A.
Published: July 2015

Objectives:

The aim of the study was to determine the prevalence of stressful life events including (sexual) abuse in children with functional defecation disorders by performing a systematic review.

Methods:

We searched MEDLINE, EMBASE, and PsycINFO for cohort, case‐control and cross‐sectional studies investigating the prevalence of stressful life events, including (sexual) abuse in children with functional defecation disorders.

Results:

The search yielded 946 articles, of which 8 were included with data from 654 children with functional constipation and 1931 children with (constipation‐associated) fecal incontinence (FI). Overall, children with functional defecation disorders had been significantly more exposed to stressful life events than healthy children, with prevalence rates ranging from 1.6% to 90.9%. Being bullied, being a relational victim, interruption of toilet training, punishment by parents during toilet training, and hospitalization were significantly related to FI, whereas separation from the best friend, failure in an examination, severe illness in a close family member, loss of job by a parent, frequent punishment, and living in a war‐affected area were significantly related to constipation. Only 1 study measured the prevalence of child abuse, which reported a significantly higher prevalence of child (sexual) abuse in children with FI compared with controls.

Conclusions:

The prevalence of stressful life events, including (sexual) abuse is significantly higher in children with functional defecation disorders compared with healthy children. To gain more insight into the true prevalence of child (sexual) abuse in children with functional defecation disorders, more studies are clearly needed.
Baseline Characteristics and Disease Phenotype in Inflammatory Bowel Disease
Authors: Müller Katalin E. , Lakatos Peter L. , Kovacs Judit B. , Arato Andras , Varkonyi Agnes , Nemes Eva , Tarnok Andras , Toth Gergely , Papp Maria , Solyom Eniko , Horvath Agnes , Guthy Ildiko , Kovacs Marta ,   Hungarian Pediatric IBD Registry Group, Veres Gabor
Published: July 2015

Objectives:

Predicting short‐term relapses and long‐term prognosis is of utmost importance in paediatric inflammatory bowel disease (IBD). Our aim was to investigate the short‐term disease outcome and medication during the first year in a paediatric incident cohort from Hungary. In addition, association laboratory markers and disease activity indices with short‐term disease outcome and medication were analysed.

Methods:

From January 1, 2008 to December 31, 2010, demographic data and clinical characteristics of newly diagnosed paediatric patients with IBD <18 years of age were prospectively recorded.

Results:

A total of 420 patients were identified (Crohn disease [CD] 266 and ulcerative colitis [UC] 124). Initially, 48% (124/256) of the patients with CD had moderate‐to‐severe disease (Pediatric Crohn's Disease Activity Index [PCDAI] >31), and this rate decreased to 2.1% at 1‐year follow‐up. Proportion of patients with UC with moderate‐to‐severe disease (Pediatric Ulcerative Colitis Activity Index >35) at diagnosis declined from 57.5% (69/120) to 6.8% at 1‐year follow‐up. Terminal ileal involvement correlated with higher initial C‐reactive protein (CRP) (P = 0.021) and initial PCDAI (P = 0.026). In UC, elevated CRP (P = 0.002) was associated with disease extension. CRP and PCDAI at diagnosis were associated with the need for immunomodulators at 1 year in children with CD. Initial CRP was also associated with the need for immunomodulators in patients with UC at 1‐year follow‐up.

Conclusions:

At diagnosis, half of the patients with IBD had moderate‐to‐severe disease, and this rate decreased to <10% after 1 year. Initial CRP and PCDAI were related to the need for aggressive therapy in CD.
Malignant Eccrine Spiradenoma of the Face
Authors: Nyame Theodore T. , Mattos David , Lian Christine G. , Granter Scott R. , Laga Alvaro C. , Caterson E.J.
Published: July 2015

Malignant eccrine spiradenoma, or spiradenocarcinoma, is an exceedingly rare sweat-gland tumor, with only 102 reported cases. Low-grade carcinomas are especially rare with only a few cases reported. Because of the limited number of case reports, the biologic behavior of low-grade malignant eccrine spiradenoma is poorly understood and no evidence-based therapeutic approach is established. Here, the authors report a 29-year-old woman who presented with a history of left-sided facial lesions present since the age of 2 months. Histopathologic examination revealed multiple benign spiradenomas, several of which showed foci of low-grade malignant transformation evidenced by loss of the characteristic 2-cell population seen in the benign tumor component. Included are the clinical presentation, histopathologic description, and surgical decision making in an effort to guide recognition of this rare entity.
Comparison of the Effects of Low-Level Laser Therapy and Ozone Therapy on Bone Healing
Authors: Alan Hilal , Vardi Nigar , Özgür Cem , Hüseyin Ahmet , Yolcu Ümit , Doğan Derya Ozdemir
Published: July 2015

This study aims to compare the effect of low-level laser therapy (LLLT) and ozone therapy on the bone healing. Thirty-six adult male Wistar albino rats were used for this study. Monocortical defects were shaped in right femur of all rats. Defects were filled with nano-hydroxyapatite graft. The animals were divided into 3 groups and each group was than divided into 2 subgroups. Then, LLLT with a diode laser was applied to the first group (G1), ozone therapy was applied to the second group (G2), and no treatment was applied to the third group as a control group (G3). Animals were sacrificed after 4th and 8th weeks and the sections were examined to evaluate the density of the inflammation, the formation of connective tissue, the osteogenic potential, and osteocalcin activity. As a result, there were no significant differences among the groups of 4 weeks in terms of new bone formation. In the immunohistochemical assessment, the number of osteocalcin-positive cells was higher in the laser group compared to the other group of 4 weeks; this difference was statistically significant in the LLLT and ozone groups (P < 0.05). Histomorphometric assessment showed that the new bone areas were higher in the LLLT and ozone groups; furthermore, there was a statistically significant difference in the LLLT in comparison with the control group at 8th week (P < 0.05). At the same time immunohistochemical assessment showed that osteocalcin-positive cells were considerably higher in G2 than G1 at 8th week (P < 0.05). The findings of this study may be the result of differences in the number of treatment sessions. Further studies are therefore needed to determine the optimal treatment modality.
Effect of the Rhinoplasty Technique and Lateral Osteotomy on Periorbital Edema and Ecchymosis
Authors: Kiliç Caner , Tuncel Ümit , Cömert Ela , Şencan Ziya
Published: July 2015

Aim:

The present study aimed to compare edema and ecchymosis in the early and late postoperative periods following the application of different surgical techniques (open and endonasal) and different types of lateral osteotomy (internal and external).

Methods:

The files and photographs of a total of 120 patients whose records were regularly maintained/updated and who underwent septorhinoplasty operation with the same surgeon were retrospectively evaluated. Sixty-nine (57.5%) patients were women and 51 (43.5%) were men. The patients were divided into 4 different groups according to the operations they underwent as follows—Group I: open technique septorhinoplasty + internal/continuous lateral osteotomy; Group II: endonasal rhinoplasty + internal/continuous lateral osteotomy; Group III: open technique septorhinoplasty + external/perforating lateral osteotomy; and Group IV: endonasal rhinoplasty + external/perforating lateral osteotomy. Postoperative edema and ecchymosis, and lateral nasal wall mucosal damage because of osteotomy were evaluated.

Results:

Postoperative second day edema and ecchymosis scores were statistically significantly better in patients in Group II compared with the patients in Group I (P = 0.010 and P = 0.004, respectively). Postoperative first day edema and postoperative seventh day ecchymosis scores were statistically significantly better in the patients in Group IV compared with the patients in Group III (P = 0.025 and P = 0.011, respectively). Intraoperative bleeding was similar in all groups. The nasal tip was more flexible in patients who underwent closed technique rhinoplasty. Unilateral mucosal damage occurred in 3 patients (4%) with internal lateral osteotomy, whereas no mucosal damage was present in patients with external osteotomy.

Conclusions:

The difference in the rate of edema and ecchymosis in the early postoperative period between the closed technique rhinoplasty and the open surgical approach was statistically significant, whereas osteotomy did not cause a significant difference. According to these results, the authors suggest endonasal surgery to prevent the development of edema and ecchymosis, whereas the choice of lateral osteotomy should be dependent on the experience of the surgeon.
Oval Window Temperature Changes in an Endoscopic Stapedectomy
Authors: Dundar Riza , Bulut Hüsamettin , Güler Osman Kadir , Yükkaldiran Ahmet , Demirtaş Yunus , Iynen Ismail , Bozkuş Ferhat , Kulduk Erkan
Published: July 2015

Objectives:

Following the initial use of endoscopes in otology, the pros and cons of these instruments have been questioned increasingly. These instruments cause an increase in temperature that needs to be investigated. In this study, the authors aimed to investigate the temperature increase caused by endoscopes and light sources in the perilymph by performing a stapedotomy in an animal model under anesthesia.

Study design:

The study was performed in a guinea pig model.

Methods:

In the animal model, a simulated otologic stapes surgery was performed at room temperature. The body temperatures of the guinea pigs were monitored; the temperature increase caused by the 0-degree rigid endoscopes with diameters of 3 and 4 mm as well as the light sources, including halogen, light-emitting diode (LED), and xenon lamps, were monitored following the stapedotomy to measure and document the continuous temperature increase in the perilymph using sensors placed at the oval window.

Results:

Rigid endoscopes cause a temperature increase in the tympanum regardless of their diameter when used with xenon and halogen light sources. The LED light caused a relatively small temperature increase.

Conclusions:

The endoscopic instruments used in the stapes operation caused a temperature increase in the oval window. The authors concluded that this heat could easily be transmitted to the cochlea by the perilymph, which has obstructed contact with the outer environment following stapedomy, resulting in neurosensorial damage.
Walking dynamics are symmetric (enough)
Authors: Ankaralı M. Mert , Sefati Shahin , Madhav Manu S. , Long Andrew , Bastian Amy J. , Cowan Noah J.
Published: July 2015

Many biological phenomena such as locomotion, circadian cycles and breathing are rhythmic in nature and can be modelled as rhythmic dynamical systems. Dynamical systems modelling often involves neglecting certain characteristics of a physical system as a modelling convenience. For example, human locomotion is frequently treated as symmetric about the sagittal plane. In this work, we test this assumption by examining human walking dynamics around the steady state (limit-cycle). Here, we adapt statistical cross-validation in order to examine whether there are statistically significant asymmetries and, even if so, test the consequences of assuming bilateral symmetry anyway. Indeed, we identify significant asymmetries in the dynamics of human walking, but nevertheless show that ignoring these asymmetries results in a more consistent and predictive model. In general, neglecting evident characteristics of a system can be more than a modelling convenience—it can produce a better model.
The external PASTA domain of the essential serine/threonine protein kinase PknB regulates mycobacterial growth
Authors: Turapov Obolbek , Loraine Jessica , Jenkins Christopher H. , Barthe Philippe , McFeely Daniel , Forti Francesca , Ghisotti Daniela , Hesek Dusan , Lee Mijoon , Bottrill Andrew R. , Vollmer Waldemar , Mobashery Shahriar , Cohen-Gonsaud Martin , Mukamolova Galina V.
Published: July 2015

PknB is an essential serine/threonine protein kinase required for mycobacterial cell division and cell-wall biosynthesis. Here we demonstrate that overexpression of the external PknB_PASTA domain in mycobacteria results in delayed regrowth, accumulation of elongated bacteria and increased sensitivity to β-lactam antibiotics. These changes are accompanied by altered production of certain enzymes involved in cell-wall biosynthesis as revealed by proteomics studies. The growth inhibition caused by overexpression of the PknB_PASTA domain is completely abolished by enhanced concentration of magnesium ions, but not muropeptides. Finally, we show that the addition of recombinant PASTA domain could prevent regrowth ofMycobacterium tuberculosis, and therefore offers an alternative opportunity to control replication of this pathogen. These results suggest that the PknB_PASTA domain is involved in regulation of peptidoglycan biosynthesis and maintenance of cell-wall architecture.
Cellular Population Dynamics Control the Robustness of the Stem Cell Niche
Authors: MacLean Adam L , Kirk Paul , Stumpf Michael PH
Published: July 2015

Within populations of cells, fate decisions are controlled by an indeterminate combination of cell-intrinsic and cell-extrinsic factors. In the case of stem cells, the stem cell niche is believed to maintain "stemness" through communication and interactions between the stem cells and one or more other cell-types that contribute to the niche conditions. To investigate the robustness of cell fate decisions in the stem cell hierarchy and the role that the niche plays, we introduce simple mathematical models of stem and progenitor cells, their progeny and their interplay in the niche. These models capture the fundamental processes of proliferation and differentiation and allow us to consider alternative possibilities regarding how niche-mediated signalling feedback regulates the niche dynamics. Generalised stability analysis of these stem cell niche systems enables us to describe the stability properties of each model. We find that although the number of feasible states depends on the model, their probabilities of stability in general do not: stem cell--niche models are stable across a wide range of parameters. We demonstrate that niche-mediated feedback increases the number of stable steady states, and show how distinct cell states have distinct branching characteristics. The ecological feedback and interactions mediated by the stem cell niche thus lend (surprisingly) high levels of robustness to the stem and progenitor cell population dynamics. Furthermore, cell--cell interactions are sufficient for populations of stem cells and their progeny to achieve stability and maintain homeostasis. We show that the robustness of the niche -- and hence of the stem cell pool in the niche -- depends only weakly, if at all, on the complexity of the niche make-up: simple as well as complicated niche systems are capable of supporting robust and stable stem cell dynamics.
Accounting for genotype uncertainty in the estimation of allele frequencies in autopolyploids
Authors: Blischak Paul D , Kubatko Laura S , Wolfe Andrea D
Published: July 2015

Despite the increasing opportunity to collect large-scale data sets for population genomic analyses, the use of high throughput sequencing to study populations of polyploids has seen little application. This is due in large part to problems associated with determining allele copy number in the genotypes of polyploid individuals (allelic dosage uncertainty--ADU), which complicates the calculation of important quantities such as allele frequencies. Here we describe a statistical model to estimate biallelic SNP frequencies in a population of autopolyploids using high throughput sequencing data in the form of read counts.We bridge the gap from data collection (using restriction enzyme based techniques [e.g., GBS, RADseq]) to allele frequency estimation in a unified inferential framework using a hierarchical Bayesian model to sum over genotype uncertainty. Simulated data sets were generated under various conditions for tetraploid, hexaploid and octoploid populations to evaluate the model's performance and to help guide the collection of empirical data. We also provide an implementation of our model in the R package POLYFREQS and demonstrate its use with two example analyses that investigate (i) levels of expected and observed heterozygosity and (ii) model adequacy. Our simulations show that the number of individuals sampled from a population has a greater impact on estimation error than sequencing coverage. The example analyses also show that our model and software can be used to make inferences beyond the estimation of allele frequencies for autopolyploids by providing assessments of model adequacy and estimates of heterozygosity.
Corporate disclosure and financing arrangements
Authors: Hasan Iftekhar , Song Liang , Zhan Meisong , Zhang Peng , Zhang Zhaoguo
Published: July 2015

Purpose

– The purpose of this paper is to explore how firms’ disclosure standards influence the syndicated loan market, with an emphasis on loan syndicate structure and composition.

Design/methodology/approach

– To empirically investigate the effects of corporate disclosure on bank loan syndicate structure and composition, the authors hand-match Dealscan, Worldscope, and other databases and construct a sample across 11 emerging markets.

Findings

– The authors found that lead banks retain less ownership and form a less-concentrated loan syndicate when borrowers have superior disclosure policies. The authors also concluded that lead banks select more foreign participants in a loan syndicate and these members retain more ownership when borrowers have high disclosure rankings. Finally, the authors present evidence that the relationship between corporate disclosure and bank loan syndicates is more significant for firms with better governance.

Originality/value

– The findings suggest that corporate disclosure has a significant influence on financing arrangements, even in a weak governance environment.
Do problem directors affect firm operating performance?
Authors: Bhuiyan Md. Borhan Uddin
Published: July 2015

Purpose

– The purpose of this paper is to examine empirically the consequences of having problem directors on the board with respect to operating performance. Problem directors are directors who have a past history of managerial integrity weakness.

Design/methodology/approach

– This paper uses three measures of operating performance to investigate the impact of problem directors and applies regression analysis to data from S & P 500 companies from 2004 to 2009.

Findings

– The author found evidence for the problem that director affiliated firms have more board and independent members. The CEO dual firm has a comparatively higher number of problem directors on the board. Firm operating performance is reduced when a board is served by a problem director. The results are consistent for a number of sensitivity tests.

Practical implications

– Results provide evidence that firms have negative performance consequences when monitored by a director with a lack of managerial integrity. The practical implication of this study is that corporate boards should appoint directors who have a clean professional background so that more vigilant monitoring by directors can be ensured.

Originality/value

– This study goes beyond the traditional focus on corporate governance and firm performance. The author uses problem directors as an indicator of governance quality to measure firm performance. To the best of the author’s knowledge, this paper is the first to investigate the consequences of firms holding problem directors on the board. This issue has implications for investors, auditors, directors and regulators.
Neither-nor: career success of women in an Arab Middle Eastern context
Authors: Tlaiss Hayfaa
Published: July 2015

Purpose

– Few studies examine the career success of women in the Arab Middle East. With that in mind, the purpose of this paper is to explore the conceptualizations of the career success of women managers in Lebanon. Drawing on the individual, behavioral, and structural approaches, this study also investigates the women’s approaches to career success. Capitalizing on the institutional theory (IT), the current investigation accounts for the complexity of the local context by illustrating how a diverse set of socio-cultural values and norms, institutional constraints, and individual agency impact the overall experience of career success among Arab women.

Design/methodology/approach

– This study is exploratory in nature and draws on a qualitative approach. In-depth, face-to-face, open-ended interviews were conducted with women managers across the managerial hierarchy in a wide range of industries, sectors, and organizations.

Findings

– The findings suggest that the Lebanese women managers’ career success was not conceptualized exclusively using the objective or the subjective measures. Rather, it was conceptualized on a continuum between these measures, thus challenging the rigid objective/subjective dichotomy in the context of Lebanon. The results also suggest that the career success of these women managers is better predicted and explained by the individual and behavioral approaches than by the traditional, structural approach. This empirical work sheds light on the gendered working conditions that women experience and how they capitalize on their individual agency to survive the hegemonic masculinity embedded in their workplaces, along with the inequalities that it promotes.

Originality/value

– This study is the first to explore the conceptualizations and the determinants of the career success of women managers in Lebanon. However, the originality of this paper is not only limited to its contribution to the limited research on the careers of Arab women; it also extends to its usage of various approaches to predict career success as well as to adapt IT as a theoretical framework for capturing the myriad of factors that impact women’s careers and success. The originality of this study also lies in advancing the theoretical concept of hegemonic masculinity into studies looking at Arab women’s career experiences by shedding some light on how the reproduction of gender, gendered working practices, and agency impact their career success.
Small firm training: just meeting the day-to-day needs of the business
Authors: Barrett Rowena
Published: July 2015

Purpose

– The purpose of this paper is to explore what the attitudes of small firm owner-managers are to developing the skills of their key resources and then examine how these and other factors affect owner-managers’ preferences for training these employees.

Design/methodology/approach

– This study of training in small road transport firms in West Australia is cast in light of the literature on human resource management in small firms underpinned by insights drawn using the resource based view of the firm. Small firms (less than 20 people) dominate this industry, while the increasing freight task, and extreme distances between West Australian ports, towns and mines highlight this sectors’ importance. Survey results from 39 small road transport firms and interviews with nine owner-managers are analysed.

Findings

– Legislative, regulatory and licensing requirements were shown to be a key determinant of skills development. Employers ensured that basic standards for employee certification and qualification were met, as the penalty for not doing so would be too high. Regulations drove the need for certain types of training – licenses, fatigue management, occupational health and safety, handling dangerous goods, the Maritime Security Identification Card card, forklift license, mine site inductions – while owner-managers knew where to get the training their staff needed. Although regulation appeared most visible in prescribing what happened in relation to training for drivers, the relevance of owner-managers’ attitudes could not be ignored, nor could conditions in the firms external environment as this shaped how these requirements were met.

Research limitations/implications

– The RBV is useful in showing how skill development enabled similarity in skills across firms, while the attitudes owner-managers and economic and social conditions meant what happened in firms around skill development varied. The importance of small firm owner-managers’ attitudes are clearly highlighted and shown to influence organizational decisions and choices around training, but these were not independent of the regulatory framework and the economic and social conditions within which the firm operated. The small firms in this study did engage workers in formal training when necessary but it was put in the context of the idiosyncratic approach of the owner-manager and the day-to-day needs of the firm. “Training” was essentially about ensuring certain types of skills were held by employees and then passing on knowledge to ensure the behavior of employees was consistent with the owner-manager’s vision for the firm in its current environment.

Originality/value

– Ways industry and government can encourage training activity that goes beyond the day-to-day firm needs are suggested.
A study of the psycho, social,
&
economic impact of a US Habitat for Humanity affiliate
Authors: Eriks Christine , Decker Phillip J , Ainsworth Natalie , Ward Rachel , Durand Roger , Mitchell Jordan , Beck Courtney
Published: July 2015

Purpose

– The purpose of this paper is to inform funders and potential funders alike of the likely outcomes of their financial contributions. Additionally, the authors reported on the assessment of the underlying logic model or theoretical underpinnings of what the authors will term the “Habitat Model.”

Design/methodology/approach

– This study utilized a one-shot case study design to obtain data. In a one-shot case study the experimental group is exposed to the independent variable (X), then observations of the dependent variable (O) were made. No observations were made before the independent variable was introduced. A one-shot case study design was necessary as this is the first impact study conducted by BAHFH because of the changes within BAHFH over the years as well as the lack of consistent archival data on families and operations.

Findings

– Most of the feedback obtained from stakeholders was positive. Many of the demographic variables showed significant improvement in partner family life style since moving into a Habitat house.

Practical implications

– The findings of this study provide evidence of positive economic, social, and psychological impacts on families participating in BAHFH homeownership and on their communities. It also showed substantial economic impacts on the communities served. Furthermore, this study showed that other stakeholders in the process were substantially and positively impacted. Finally, this study pointed to a number of things that BAHFH needed to change such as homeowner education, financial counseling, and the opening of a local ReStore.

Originality/value

– The current study provides data that provide evidence of positive economic, social, and psychological impacts on families participating in BAHFH homeownership opportunities.