bluuebunny/crossref_metadata_2025 huggingface dataset:
Representation of different exact numbers of prey by a spider-eating predator
Authors: Cross Fiona R. , Jackson Robert R.
Published: April 2017

Our objective was to use expectancy-violation methods for determining whetherPortia africana, a salticid spider that specializes in eating other spiders, is proficient at representing exact numbers of prey. In our experiments, we relied on this predator's known capacity to gain access to prey by following pre-planned detours. AfterPortiafirst viewed a scene consisting of a particular number of prey items, it could then take a detour during which the scene went out of view. Upon reaching a tower at the end of the detour,Portiacould again view a scene, but now the number of prey items might be different. We found that, compared with control trials in which the number was the same as before,Portia's behaviour was significantly different in most instances when we made the following changes in number: 1 versus 2, 1 versus 3, 1 versus 4, 2 versus 3, 2 versus 4 or 2 versus 6. These effects were independent of whether the larger number was seen first or second. No significant effects were evident when the number of prey changed between 3 versus 4 or 3 versus 6. When we changed prey size and arrangement while keeping prey number constant, no significant effects were detected. Our findings suggest thatPortiarepresents 1 and 2 as discrete number categories, but categorizes 3 or more as a single category that we call ‘many’.
Convergent? Minds? Some questions about mental evolution
Authors: Cartmill Matt
Published: April 2017

In investigating convergent minds, we need to be sure that the things we are looking at are both minds and convergent. In determining whether a shared character state represents a convergence between two organisms, we must know the wider distribution and primitive state of that character so that we can map that character and its state transitions onto a phylogenetic tree. When we do this, some apparently primitive shared traits may prove to represent convergent losses of cognitive capacities. To avoid having to talk about the minds of plants and paramecia, we need to go beyond assessments of behaviourally defined cognition to ask questions about mind in the primary sense of the word, defined by the presence of mental events and consciousness. These phenomena depend upon the possession of brains of adequate size and centralized ontogeny and organization. They are probably limited to vertebrates. Recent discoveries suggest that consciousness is adaptively valuable as a late error-detection mechanism in the initiation of action, and point to experimental techniques for assessing its presence or absence in non-human mammals.
Increasing suppression of saccade-related transients along the human visual hierarchy
Authors: Golan Tal , Davidesco Ido , Meshulam Meir , Groppe David M , Mégevand Pierre , Yeagle Erin M , Goldfinger Matthew S , Harel Michal , Melloni Lucia , Schroeder Charles E , Deouell Leon Y , Mehta Ashesh D , Malach Rafael
Published: April 2017

A key hallmark of visual perceptual awareness is robustness to instabilities arising from unnoticeable eye and eyelid movements. In previous human intracranial (iEEG) work (Golan et al., 2016) we found that excitatory broadband high-frequency activity transients, driven by eye blinks, are suppressed in higher-level but not early visual cortex. Here, we utilized the broad anatomical coverage of iEEG recordings in 12 eye-tracked neurosurgical patients to test whether a similar stabilizing mechanism operates following small saccades. We compared saccades (1.3°-3.7°) initiated during inspection of large individual visual objects with similarly-sized external stimulus displacements. Early visual cortex sites responded with positive transients to both conditions. In contrast, in both dorsal and ventral higher-level sites the response to saccades (but not to external displacements) was suppressed. These findings indicate that early visual cortex is highly unstable compared to higher-level visual regions which apparently constitute the main target of stabilizing extra-retinal oculomotor influences.
Redundancy in synaptic connections enables neurons to learn optimally
Authors: Hiratani Naoki , Fukai Tomoki
Published: April 2017

Recent experimental studies suggest that, in cortical microcircuits of the mammalian brain, the majority of neuron-to-neuron connections are realized by multiple synapses. However, it is not known whether such redundant synaptic connections provide any functional benefit. Here, we show that redundant synaptic connections enable near-optimal learning in cooperation with synaptic rewiring. By constructing a simple dendritic neuron model, we demonstrate that with multisynaptic connections, synaptic plasticity approximates a sample-based Bayesian filtering algorithm known as particle filtering, and wiring plasticity implements its resampling process. Applying the proposed framework to a detailed single neuron model, we show that the model accounts for many experimental observations, including the dendritic position dependence of spike-timing-dependent plasticity, and the functional synaptic organization on the dendritic tree based on the stimulus selectivity of presynaptic neurons. Our study provides a novel conceptual framework for synaptic plasticity and rewiring.
Effects of Bisphenol A on Incidence and Severity of Cardiac Lesions in the NCTR-Sprague-Dawley Rat: A CLARITY-BPA Study
Authors: Gear Robin , Kendziorski Jessica A. , Belcher Scott M.
Published: April 2017

The goal of this study was to determine whether bisphenol A (BPA) had adverse effects indicative of cardiac toxicity. As part of the “Consortium Linking Academic and Regulatory Insights on BPA Toxicity” (CLARITY-BPA), study dams and offspring were exposed by daily gavage to five doses of BPA ranging from 2.5 to 25000 μg/kg/day, 0.05 or 0.5 μg/kg/day 17α-ethinyl-estradiol (EE) or 0.3% carboxymethylcellulose vehicle. Exposure-related effects were analyzed in isolated hearts by quantitative morphometry and histopathology. No dose-related changes in body weight were detected. Across all exposure groups including vehicle controls, body weight of continuously dosed males was reduced compared to males dosed only until PND21. Heart weight was increased only in females exposed to EE, and consistent alterations in LV wall thickness were not observed. Exposure-related changes in collagen accumulation were minor and limited to highest EE exposure groups with increased collagen accumulation in PND21 males. Decreased collagen was observed in hearts of BPA or EE exposed females at PND90 and PND180. In BPA or EE treated females cardiomyopathy incidence and severity was significantly increased compared to control females at PND21 with myocardial degeneration observed in both males and females at PND21 and PND90.
Sparse Graphical Models for Functional Connectivity Networks: Best Methods and the Autocorrelation Issue
Authors: Zhu Yunan , Cribben Ivor
Published: April 2017

Sparse graphical models are frequently used to explore both static and dynamic functional brain networks from neuroimaging data. However, the practical performance of the models has not been studied in detail for brain networks. In this work, we have two objectives. First, we compare several sparse graphical model estimation procedures and several selection criteria under various experimental settings, such as different dimensions, sample sizes, types of data, and sparsity levels of the true model structures. We discuss in detail the superiority and deficiency of each combination. Second, in the same simulation study, we show the impact of autocorrelation and whitening on the estimation of functional brain networks. We apply the methods to a resting-state functional magnetic resonance imaging (fMRI) data set. Our results show that the best sparse graphical model, in terms of detection of true connections and having few false-positive connections, is the smoothly clipped absolute deviation (SCAD) estimating method in combination with the Bayesian information criterion (BIC) and cross-validation (CV) selection method. In addition, the presence of autocorrelation in the data adversely affects the estimation of networks but can be helped by using the CV selection method. These results question the validity of a number of fMRI studies where inferior graphical model techniques have been used to estimate brain networks.
The rate of transient beta frequency events predicts impaired function across tasks and species
Authors: Shin Hyeyoung , Law Robert , Tsutsui Shawn , Moore Christopher I. , Jones Stephanie R.
Published: April 2017

Beta frequency oscillations (15-29Hz) are among the most prominent signatures of brain activity. Beta power is predictive of many healthy and abnormal behaviors, including perception, attention and motor action. Recent evidence shows that in non-averaged signals, beta can emerge as transient high-power “events”. As such, functionally relevant differences in averaged power across time and trials can reflect accumulated changes in the number, power, duration, and/or frequency span of the events. We show for the first time that functionally relevant differences in averaged prestimulus beta power in human sensory neocortex reflects a difference in the number of high-power beta events per trial, i.e., the rate of events. Further, high power beta events close to the time of the stimulus were more likely to impair perception. This result is consistent across detection and attention tasks in human magnetoencephalography (MEG) and is conserved in local field potential (LFP) recordings of mice performing a detection task. Our findings suggest transient brain rhythms are best viewed as a “rate metric” in their impact on function, and provides a new framework for understanding and manipulating functionally relevant rhythmic events.
Development of a Self-Report Measure of Reward Sensitivity: A Test in Current and Former Smokers
Authors: Hughes John R , Callas Peter W , Priest Jeff S , Etter Jean-Francois , Budney Alan J , Sigmon Stacey C
Published: April 2017

Introduction

Tobacco use or abstinence may increase or decrease reward sensitivity. Most existing measures of reward sensitivity were developed decades ago, and few have undergone extensive psychometric testing.

Methods

We developed a 58-item survey of the anticipated enjoyment from, wanting for, and frequency of common rewards (the Rewarding Events Inventory – REI). The current analyses focuses on ratings of anticipated enjoyment. The first validation study recruited current and former smokers from internet sites. The second study recruited smokers who wished to quit and monetarily reinforced them to stay abstinent in a laboratory study, and a comparison group of former smokers. In both studies, participants completed the inventory on two occasions, 3-7 days apart. They also completed four anhedonia scales and a behavioral test of reduced reward sensitivity.

Results

Half of the enjoyment ratings loaded on four factors: socializing, active hobbies, passive hobbies, and sex/drug use. Cronbach alpha coefficients were all ≥ 0.73 for overall mean and factor scores. Test-retest correlations were all ≥ 0.83. Correlations of the overall and factor scores with frequency of rewards, anhedonia scales were 0.19 – 0.53, except for the sex/drugs factor. The scores did not correlate with behavioral tests of reward and did not differ between current and former smokers. Lower overall mean enjoyment score predicted a shorter time to relapse.

Discussion

Internal reliability and test-retest reliability of the enjoyment outcomes of the REI are excellent, and construct and predictive validity are modest but promising. The REI is comprehensive and up-to-date, yet is short enough to use on repeated occasions. Replication tests, especially predictive validity tests, are needed.

Implications

Both use of and abstinence from nicotine appears to increase or decrease how rewarding non-drug rewards are; however, self-report scales to test this have limitations. Our inventory of enjoyment from 58 rewards appears to be reliable and valid as well as comprehensive and up-to-date, yet is short enough to use on repeated occasions. Replication tests, especially of the predictive validity of our scale, are needed.
Microbial community assembly differs by mineral type in the rhizosphere
Authors: Whitman Thea , Neurath Rachel , Perera Adele , Ning Daliang , Zhou Jizhong , Nico Peter , Pett-Ridge Jennifer , Firestone Mary
Published: April 2017

Inputs of root carbon (C) fuel growth of nearby soil microorganisms. If these microbes associate with soil minerals, then mineral-microbiome complexes near roots could be a gateway towards stabilization of soil carbon and may influence the quantity and quality of persistent SOM. To investigate the interactions between roots, soil minerals, and microbes, we incubated three types of minerals (ferrihydrite, kaolinite, quartz) and a native soil mineral fraction near roots of a common Californian annual grass,Avena barbata,growing in its resident soil. We followed microbial colonization of these minerals for 2.5 months – the plant’s lifespan. Bacteria and fungi that colonized mineral surfaces during this experiment differed across mineral types and differed from those in the background soil, implying microbial colonization was the result of processes in addition to passive movement with water to mineral surfaces. Null model analysis revealed that dispersal limitation was a dominant factor structuring mineral-associated microbial communities for all mineral types. Once bacteria arrived at a mineral surface, capacity for rapid growth appeared important, as ribosomal copy number was significantly correlated with relative enrichment on minerals.Glomeromycota(a phylum associated with arbuscular mycorrhizal fungi) appeared to preferentially associate with ferrihydrite surfaces. The mechanisms enabling colonization of soil minerals may be foundational to the overall soil microbiome composition and partially responsible for the persistence of C entering soil via plant roots.
Fine-mapping of genetic loci driving spontaneous clearance of hepatitis C virus infection
Authors: Huang Hailiang , Duggal Priya , Thio Chloe L. , Latanich Rachel , Goedert James J. , Mangia Alessandra , Cox Andrea L. , Kirk Gregory D. , Mehta Shruti , Blankson Joel N. , Aneja Jasneet , Alric Laurent , Donfield Sharyne M. , Cramp Matthew E. , Khakoo Salim I. , Tobler Leslie H. , Busch Michael , Alexander Graeme J. , Rosen Hugo R. , Edlin Brian R. , Lauer Georg M. , Thomas David L. , Daly Mark J. , Chung Raymond T. , Kim Arthur Y.
Published: April 2017

Approximately three quarters of acute HCV infections evolve to a chronic state, while one quarter are spontaneously cleared. Genetic predispositions strongly contribute to the development of chronicity. We have conducted a genome-wide association study to identify genomic variants underlying HCV spontaneous clearance using Immunochip in European and African ancestries. We confirmed two previously reported significant associations, in theIL28B/IFNL41,2and MHC regions, with spontaneous clearance in the European population. We further fine-mapped the MHC association to a region of about 50 kilo base pairs, down from 1 mega base pairs in the previous study. Additional analyses suggested that the association in the MHC locus might be significantly stronger for virus subtype 1a than 1b, suggesting that viral subtype may have influenced the genetic mechanism underlying the clearance of HCV.
Conservation of single amino-acid polymorphisms inPlasmodium falciparumerythrocyte membrane protein 1 and association with severe pathophysiology
Authors: Zinder Daniel , Rorick Mary M. , Tiedje Kathryn E. , Ruybal-Pesántez Shazia , Day Karen P. , Pascual Mercedes
Published: April 2017

Plasmodium falciparumerythrocyte membrane protein 1(PfEMP1)is a parasite protein encoded by a multigene family known asvar.Expressed on the surface of infected red blood cells,PfEMP1plays a central role in parasite virulence. TheDBLαdomain ofPfEMP1contains short sequence motifs termed homology blocks. Variation within homology blocks, at the level of single amino-acid modifications, has not been considered before in association with severe disease. Here we identify a total of 2701 amino-acid polymorphisms withinDBLαhomology blocks, the majority of which are shared between two geographically distant study populations in existing transcription data from Kenya and in a new genomic dataset sampled in Ghana. Parasitemia levels and the transcription levels of specific polymorphisms are as predictive of severe disease (AUC=0.83) and of the degree of rosetting (forecast skill SS=0.45) as the transcription of classicvargroups. 11 newly categorized polymorphisms were strongly correlated withgrpA vargene expression (SS=0.93) and a different set of 16 polymorphisms was associated with theH3subset (SS=0.20). These associations provide the basis for a novel method of relating pathophysiology to parasite gene expression levels—one that, being site-specific, has more molecular detail than previous models based onvargroups or homology blocks. This newly described variation influences disease outcome, and can help develop anti-malarial intervention strategies such as vaccines that target severe disease. Further replication of this analysis in geographically disparate populations and for larger sample sizes can help improve the identification of the molecular causes of severe disease.
Human Rab small GTPase- and class V myosin-mediated membrane tethering in a chemically defined reconstitution system
Authors: Inoshita Motoki , Mima Joji
Published: April 2017

Membrane tethering is a fundamental process essential for compartmental specificity of intracellular membrane trafficking in eukaryotic cells. Rab-family small GTPases and specific sets of Rab-interacting effector proteins, including coiled-coil tethering proteins and multisubunit tethering complexes, have been reported to be responsible for membrane tethering. However, whether and how these key components directly and specifically tether subcellular membranes still remains enigmatic. Using chemically defined proteoliposomal systems reconstituted with purified human Rab proteins and synthetic liposomal membranes to study the molecular basis of membrane tethering, we established here that Rab-family GTPases have a highly conserved function to directly mediate membrane tethering, even in the absence of any types of Rab effectors such as the so-called tethering proteins. Moreover, we demonstrate that membrane tethering mediated by endosomal Rab11a is drastically and selectively stimulated by its cognate Rab effectors, class V myosins (Myo5A and Myo5B), in a GTP-dependent manner. Of note, Myo5A and Myo5B exclusively recognized and cooperated with the membrane-anchored form of their cognate Rab11a to support membrane tethering mediated bytrans-Rab assemblies on apposing membranes. Our findings support the novel concept that Rab-family proteins provide abona fidemembrane tether to physically and specifically link two distinct lipid bilayers of subcellular membranes. They further indicate that Rab-interacting effector proteins, including class V myosins, can regulate these Rab-mediated membrane tethering reactions.
Dissecting telomere maintenance mechanisms in pediatric glioblastoma
Authors: Deeg Katharina I. , Chung Inn , Poos Alexandra M. , Braun Delia M. , Korshunov Andrey , Oswald Marcus , Kepper Nick , Bender Sebastian , Castel David , Lichter Peter , Grill Jacques , Pfister Stefan M. , König Rainer , Jones David T. W. , Rippe Karsten
Published: April 2017

Pediatric glioblastoma (pedGBM) represent a highly malignant primary brain tumor with recurrent mutations in the chromatin remodeler ATRX and the histone variant H3.3 that is typically associated with a fatal outcome. ATRX acts as suppressor of the alternative lengthening of telomeres (ALT) pathway, which is frequently activated in pedGBM. However, telomere features of pedGBMs have not been studied in detail, and ALT-positive model cell lines are lacking. Here, we systematically characterized a panel of pedGBM models that carry a representative set of recurrent genomic mutations for a variety of telomere features. These included the presence of ALT-associated promyelocytic leukemia nuclear bodies and C-circles, a specific type of extrachromosomal telomeric repeats, the telomere repeat content, and phosphorylation of histone H3.3 at serine 31. From an integrated analysis of seven pedGBM cell lines and 57 primary tumor samples we identified cell lines and tumors that represent the different telomere maintenance mechanisms and conclude the following: (i) A positive signal in the C-circle assay is a reliable ALT marker. (ii) ALT features occur heterogeneously and one pedGBM subgroup uses a ‘non-canonical’ ALT mechanism in the presence of wild-type ATRX. (iii) The spreading of H3.3S31 phosphorylation during mitosis is associated with loss of ATRX but not with ALTper se. (iv) In contrast to a previous study in glioma stem cells, we did not find a hypersensitivity of ALT cells towards the ATR inhibitor VE-821. (v) ALT-positive pedGBMs can be reliably identified from a classification scheme developed here that evaluates various combinations of cytogenetic and/or genomic data. Thus, our findings elucidate further details of the ALT pathway in pedGBMs, provide valuable models for evaluating ALT targeted therapies in a preclinical setting, and introduce an ALT classification scheme for primary tumor samples.
Principles for models of neural information processing
Authors: Kay Kendrick N. , Weiner Kevin S.
Published: April 2017

The goal of cognitive neuroscience is to understand how mental operations are performed by the brain. Given the complexity of the brain, this is a challenging endeavor that requires the development of formal models. Here, we provide a perspective on models of neural information processing in cognitive neuroscience. We define what these models are, explain why they are useful, and specify criteria for evaluating models. We also highlight the difference between functional and mechanistic models, and call attention to the value that neuroanatomy has for understanding brain function. Based on the principles we propose, we proceed to evaluate the merit of recently touted deep neural network models. We contend that these models are promising, but substantial work is necessary to (i) clarify what type of explanation these models provide, (ii) determine what specific effects they accurately explain, and (iii) improve our understanding of how they work.
Genomics of cellular proliferation under periodic stress
Authors: Salignon Jérôme , Richard Magali , Fulcrand Etienne , Yvert Gaël
Published: April 2017

Living systems control cell growth dynamically by processing information from their environment. Although responses to one environmental change have been intensively studied, little is known about how cells react to fluctuating conditions. Here we address this question at the genomic scale by measuring the relative proliferation rate (fitness) of 3,568 yeast gene deletion mutants in out-of-equilibrium conditions: periodic oscillations between two salinity conditions. Fitness and its genetic variance largely depended on the stress period. Surprisingly, dozens of mutants displayed pronounced hyperproliferation at short periods, identifying unexpected controllers of growth under fast dynamics. We validated the implication of the high-affinity cAMP phosphodiesterase and of a regulator of protein translocation to mitochondria in this control. The results illustrate how natural selection acts on mutations in a fluctuating environment, highlighting unsuspected genetic vulnerabilities to periodic stress in molecular processes that are conserved across all eukaryotes.
Pseudoneglect in visual search: Behavioral evidence and connectional constraints in simulated neural circuitry
Authors: Gigliotta Onofrio , Malkinson Tal Seidel , Miglino Orazio , Bartolomeo Paolo
Published: April 2017

Most people tend to bisect horizontal lines slightly to the left of their true center (pseudoneglect), and start visual search from left-sided items. This physiological leftward spatial bias may depend on hemispheric asymmetries in the organization of attentional networks, but the precise mechanisms are unknown. Here we modeled relevant aspects of the ventral and dorsal attentional networks (VAN and DAN) of the human brain. First, we demonstrated pseudoneglect in visual search in 101 right-handed psychology students. Participants consistently tended to start the task from a left-sided item, thus showing pseudoneglect. Second, we trained populations of simulated neurorobots to perform a similar task, by using a genetic algorithm. The neurorobots’ behavior was controlled by artificial neural networks, which simulated the human VAN and DAN in the two brain hemispheres. Neurorobots differed in the connectional constraints that were applied to the anatomy and function of the attention networks. Results indicated that (1) neurorobots provided with a biologically plausible hemispheric asymmetry of the VAN-DAN connections, as well as with inter-hemispheric inhibition, displayed the best match with human data; however, (2) anatomical asymmetryper sewas not sufficient to generate pseudoneglect; in addition, the VAN must have an excitatory influence on the ipsilateral DAN; (3) neurorobots provided with bilateral competence in the VAN but without inter-hemispheric inhibition failed to display pseudoneglect. These findings provide a proof of concept of the causal link between connectional asymmetries and pseudoneglect, and specify important biological constraints that result in physiological asymmetries of human behavior.

Significance statement

Most of us start our exploration of the environment from the left side. Here we demonstrated this tendency in undergraduate students, and trained artificial agents (neurorobots) to perform a similar visual search task. The neurorobots’ behavior was controlled by artificial neural networks, inspired by the human fronto-parietal attentional system. In seven distinct populations of neurorobots, different constraints were applied on the network connections within and between the brain hemispheres. Only one of the artificial populations behaved in a similar way to the human participants. The connectional constraints applied to this population included known characteristics of the human fronto-parietal networks, but had also additional properties not previously described. Thus, our findings specify biological constraints that induce physiological asymmetries of human behavior.
EBF2 transcriptionally regulates brown adipogenesis via the histone reader DPF3 and the BAF chromatin remodeling complex
Authors: Shapira Suzanne N. , Lim Hee-Woong , Rajakumari Sona , Sakers Alexander P. , Ishibashi Jeff , Harms Matthew J. , Won Kyoung-Jae , Seale Patrick
Published: April 2017

The transcription factor early B-cell factor 2 (EBF2) is an essential mediator of brown adipocyte commitment and terminal differentiation. However, the mechanisms by which EBF2 regulates chromatin to activate brown fat-specific genes in adipocytes were unknown. ChIP-seq (chromatin immunoprecipitation [ChIP] followed by deep sequencing) analyses in brown adipose tissue showed that EBF2 binds and regulates the activity of lineage-specific enhancers. Mechanistically, EBF2 physically interacts with the chromatin remodeler BRG1 and the BAF chromatin remodeling complex in brown adipocytes. We identified the histone reader protein DPF3 as a brown fat-selective component of the BAF complex that was required for brown fat gene programming and mitochondrial function. Loss of DPF3 in brown adipocytes reduced chromatin accessibility at EBF2-bound enhancers and led to a decrease in basal and catecholamine-stimulated expression of brown fat-selective genes. Notably, Dpf3 is a direct transcriptional target of EBF2 in brown adipocytes, thereby establishing a regulatory module through which EBF2 activates and also recruits DPF3-anchored BAF complexes to chromatin. Together, these results reveal a novel mechanism by which EBF2 cooperates with a tissue-specific chromatin remodeling complex to activate brown fat identity genes.
Different requirements of functional telomeres in neural stem cells and terminally differentiated neurons
Authors: Lobanova Anastasia , She Robert , Pieraut Simon , Clapp Charlie , Maximov Anton , Denchi Eros Lazzerini
Published: April 2017

Telomeres have been studied extensively in peripheral tissues, but their relevance in the nervous system remains poorly understood. Here, we examine the roles of telomeres at distinct stages of murine brain development by using lineage-specific genetic ablation of TRF2, an essential component of the shelterin complex that protects chromosome ends from the DNA damage response machinery. We found that functional telomeres are required for embryonic and adult neurogenesis, but their uncapping has surprisingly no detectable consequences on terminally differentiated neurons. Conditional knockout of TRF2 in post-mitotic immature neurons had virtually no detectable effect on circuit assembly, neuronal gene expression, and the behavior of adult animals despite triggering massive end-to-end chromosome fusions across the brain. These results suggest that telomeres are dispensable in terminally differentiated neurons and provide mechanistic insight into cognitive abnormalities associated with aberrant telomere length in humans.
Uncoupling neurogenic gene networks in the Drosophila embryo
Authors: Rogers William A. , Goyal Yogesh , Yamaya Kei , Shvartsman Stanislav Y. , Levine Michael S.
Published: April 2017

The EGF signaling pathway specifies neuronal identities in the Drosophila embryo by regulating developmental patterning genes such as intermediate neuroblasts defective (ind). EGFR is activated in the ventral midline and neurogenic ectoderm by the Spitz ligand, which is processed by the Rhomboid protease. CRISPR/Cas9 was used to delete defined rhomboid enhancers mediating expression at each site of Spitz processing. Surprisingly, the neurogenic ectoderm, not the ventral midline, was found to be the dominant source of EGF patterning activity. We suggest that Drosophila is undergoing an evolutionary transition in central nervous system (CNS)-organizing activity from the ventral midline to the neurogenic ectoderm.
Synthesis, crystal structure and study of the crystal packing in the complex bis(4-aminopyridine-κN1)dichloridocobalt(II)
Authors: Sanchez Montilva Olga Carolina , Movilla Federico , Rodriguez Maricel Gabriela , Di Salvo Florencia
Published: April 2017

Despite the large number of reported crystalline structures of coordination complexes bearing pyridines as ligands, the relevance of π–π interactions among these hereroaromatic systems in the stabilization of their supramolecular structures and properties is not very well documented in the recent literature. The title compound, [CoCl2(C5H6N2)2], was obtained as bright-blue crystals suitable for single-crystal X-ray diffraction analysis from the reaction of 4-aminopyridine with cobalt(II) chloride in ethanol. The new complex was fully characterized by a variety of spectroscopic techniques and single-crystal X-ray diffraction. The crystal structure showed a tetrahedral complex stabilized mainly by bidimensional motifs constructed by π–π interactions with large horizontal displacements between the 4-aminopyridine units, and N—H...Cl hydrogen bonds. Other short contacts, such as C—H...Cl interactions, complete the three-dimensional arrangement. The supramolecular investigation was extended by statistical studies using the Cambridge Structural Database and a Hirshfeld surface analysis.
The crystal structures of three pyrazine-2,5-dicarboxamides: three-dimensional supramolecular structures
Authors: Cati Dilovan S. , Stoeckli-Evans Helen
Published: April 2017

The complete molecules of the title compounds, N
2,N
5-bis(pyridin-2-ylmethyl)pyrazine-2,5-dicarboxamide, C18H16N6O2 (I), 3,6-dimethyl-N
2,N
5-bis(pyridin-2-ylmethyl)pyrazine-2,5-dicarboxamide, C20H20N6O2 (II), and N
2,N
5-bis(pyridin-4-ylmethyl)pyrazine-2,5-dicarboxamide, C18H16N6O2 (III), are generated by inversion symmetry, with the pyrazine rings being located about centres of inversion. Each molecule has an extended conformation with the pyridine rings inclined to the pyrazine ring by 89.17 (7)° in (I), 75.83 (8)° in (II) and by 82.71 (6)° in (III). In the crystal of (I), molecules are linked by N—H...N hydrogen bonds, forming layers lying parallel to the bc plane. The layers are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. In the crystal of (II), molecules are also linked by N—H...N hydrogen bonds, forming layers lying parallel to the (10-1) plane. As in (I), the layers are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. In the crystal of (III), molecules are again linked by N—H...N hydrogen bonds, but here form corrugated sheets lying parallel to the bc plane. Within the sheets, neighbouring pyridine rings are linked by offset π–π interactions [intercentroid distance = 3.739 (1) Å]. The sheets are linked by C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. Compound (I) crystallizes in the monoclinic space group P21/c. Another monoclinic polymorph, space group C2/c, has been reported on by Cockriel et al. [Inorg. Chem. Commun. (2008), 11, 1–4]. The molecular structures of the two polymorphs are compared.
2-{(E)-[(4-Anilinophenyl)imino]methyl}-4-[(E)-(4-methoxyphenyl)diazenyl]phenol
Authors: Faizi Md. Serajul Haque , Dege Necmi , Goleva Kateryna
Published: April 2017

In the title Schiff base compound, C26H22N4O2, the hydroxy group forms a intramolecular hydrogen bond to the imine N atom and generates anS(6) ring motif. The conformation about the C=N and N=N bonds isE. The 4-methoxybenzene ring and thep-phenylenediamine ring are inclined to the phenol ring by 11.61 (17) and 46.04 (17)°, respectively. The terminalN-phenyl ring is inclined to thep-phenylenediamine ring by 50.72 (17)°. In the crystal, adjacent molecules are linked by C—H...O hydrogen bonds, involving thep-phenylenediamine ring and the phenol ring, forming chains along [001]. The chains are linked by a number of C—H...π interactions, forming slabs propagating parallel to (100).
Electrochemical synthesis of polypyrrole-SiO2 composite coating on 316 stainless steel for corrosion protection
Authors: Yan Qun , Li Chuanxian
Published: April 2017

Purpose

The purpose of this paper is to synthesize polypyrrole/SiO2 composite coating on 316 stainless steel (316SS) by cyclic voltammogram and preliminary do research about the valuable effects of SiO2 particle incorporation within the polymer matrix.

Design/methodology/approach

This study is based on elaboration of coating by electrochemical process and of SiO2 by a sol-gel process.

Findings

Electrochemical impedance studies revealed that compared with polypyrrole (PPy), PPy-SiO2 coating acts as a more protective layer on 316SS against corrosion in 3.5 per cent NaCl. Scanning electron microscopy studies revealed that the PPy-SiO2-coated 316SS showed more uniform and compact morphology.

Originality/value

To fully disperse SiO2, a sol-gel method is used. Hydroxyl group is generated on the surface of inorganic particle by the sol-gel method, which improves the inorganic particle dispersion.
Deposition time effects on structure and corrosion resistance of duplex MAO/Al coatings on AZ31B Mg alloy
Authors: Cui Xue-Jun , Zhang Ying-Jun , Dou Bao-Jie , Zeng Xian-Guang , Lin Xiu-Zhou
Published: April 2017

Purpose

This paper aims to investigate the effects of deposition time on the structure and anti-corrosion properties of a micro-arc oxidation (MAO)/Al coating on AZ31B Mg alloy.

Design/methodology/approach

The study describes the fabrication of the coating via a combined process of MAO with multi-arc ion plating. The structure, composition and corrosion resistance of the coatings were evaluated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and electrochemical methods.

Findings

The Al-layer is tightly deposited with a good mechanical interlock along the rough interface due to the Al diffusion. However, the Al layer reduces the anti-corrosion of MAO-coated Mg alloy because of structural defects such as droplets and cavities, which act as channels for corrosive media infiltration towards the substrate. Fortunately, the Al layer improves the substrate corrosion resistance owing to its passive behaviour, and the corrosion resistance can be enhanced with increasing deposition time. All results indicate that a buffer layer fabricated through the duplex process improves the interfacial compatibility between the hard coating and soft Mg alloys.

Originality/value

An MAO/Al duplex coating was fabricated via a combined process of MAO and physical vapour deposition. MAO/Al duplex coatings exhibit obviously passive behaviours on AZ31 Mg alloy. The structure and corrosion resistance of MAO/Al coatings were investigated.
Failure analysis of coated galvanized steel panels
Authors: Ul-Hamid Anwar , Saricimen Huseyin , Quddus Abdul , Al-Hems Luai M.
Published: April 2017

Purpose

The purpose of this paper was to determine the mode and cause of failure of polyester-coated galvanized corrugated steel sheets that exhibited degradation of the coating after seven months into service.

Design/methodology/approach

Visual inspection and light microscopy revealed the extent of damage exhibited by the panels. Standard metallographic techniques were used to prepare samples obtained from both unused and failed sections. Light microscopy, scanning electron microscopy combined with energy dispersive x-ray spectroscopy and x-ray diffraction techniques were used to study the surface morphology, microstructural features, elemental composition and structure of the samples.

Findings

The failure occurred in the form of delamination and blistering of coated layer. Presence of solar radiation, humidity and water retention resulted in loss of adhesion, leading to coating delamination and flaking especially at the top surface. The coating at the bottom surface of the panels showed evidence of blistering caused by water vapor differential that existed between the environment and the coating because of prolonged (four months) wet conditions that existed at the manufacturer’s site during storage.

Practical implications

It is recommended that the coated panels are stored in covered area where direct exposure to atmospheric conditions can be prevented. If open storage is unavoidable, then the use of tarpaulin or plastic sheet as covering and vapor-phase inhibitors was recommended.

Originality/value

This paper provides an account of failure analysis of metal sheet panels. It identifies the mode and cause of failure and also provides recommendations to avoid such occurrences in the future. The information contained in this paper is useful for plant engineers and project managers working in the metal sheet industry.
A novel fixing method for Mg-based specimens used in the in-vitro immersion test
Authors: Tan Cui , Zhou Juncen , Li Qing
Published: April 2017

Purpose

The aim of this paper is to predict the in-vivo degradation behaviour of Mg-based implants through in-vitro immersion test.

Design/methodology/approach

A novel placement mode arming to mimic the in-vivo situation was investigated in this work. Specimens were mounted on bones and then immersed in dynamic Hank’s solution.

Findings

The degradation behaviour of the specimen’s two sides is unequal. The bottom side which clings to the bone was isolated from solution in the early stage. During the late immersion period, there was crevice corrosion appearing on the bottom side. Weight loss and mechanical properties of specimens were also affected by the placement mode.

Research limitations/implications

Placement mode reported here have guiding significance for degradation behaviour of bio-implants in the clinical study.

Social implications

Placement mode reported here have guiding significance for degradation behaviour of bio-implants in the clinical study.

Originality/value

A novel placement mode arming to mimic the in-vivo situation was investigated in this work, which was better fit the actualin vivoimmersion situation.
Applying a transportation rating system to advance sustainability evaluation, planning and partnerships
Authors: Barrella Elise , Lineburg Kelsey , Hurley Peter
Published: April 2017

Purpose

The purpose of this paper is to describe a pilot application of the Sustainable Transportation Analysis & Rating System (STARS), and highlight how a sustainability rating system can be used to promote sustainable urban development through a university–city partnership. STARS is an example of a second-generation “green” rating system focused on transportation planning, design, operations and maintenance.

Design/methodology/approach

In Fall 2013, James Madison University (JMU) initiated a STARS pilot demonstration using a local corridor that connects the university and the city of Harrisonburg. The pilot’s purposes were to develop attainable transportation-development targets, evaluate infrastructure and programmatic options in the context of a credit-based system and demonstrate a decision-making framework centered on sustainability optimization. The paper provides an overview of the STARS framework and the pilot’s collaborations, analysis, findings and recommendations for credits across sustainability dimensions.

Findings

Upon applying the rating system, the research team found that STARS may initially be easier to integrate into a comprehensive transportation planning process than a corridor-level evaluation due to data needs, in-house expertise and planning timelines for campus and city developments. A campus-wide master plan based on STARS would enable a university and a city to apply sustainability principles to their physical and/or policy interfaces to systemically create change and achieve quantifiable targets.

Originality/value

The STARS framework provides a novel approach for integrating multiple stakeholders (faculty, the university and city staff, students and community members) in a process of capacity building, evaluating options, policy-making, implementation and performance monitoring. The JMU pilot is the first application of STARS at a university and the only US East Coast application to date.
Assessment of undergraduate students’ environmental stewardship reasoning and knowledge
Authors: Hartman Christie-Joy Brodrick , DeMars Christine E. , Griscom Heather Peckham , Butner Harold Martin
Published: April 2017

Purpose

The purpose of this paper is to present a public university’s design and implementation of an assessment approach that measures the change in undergraduate students’ environmental stewardship reasoning and knowledge abilities over time.

Design/methodology/approach

In support of a university’s strategic emphasis on environmental stewardship, members of a university committee developed environmental stewardship learning outcomes for undergraduate students. The learning outcomes were not required in specific academic courses or in general education. Subsequently, volunteers from a variety of roles, in cooperation with committee members, developed a corresponding assessment test that focused on reasoning and knowledge. The instrument was revised between Spring 2011 and Spring 2014, and its validity was evaluated. An exploratory analysis of student learning over time was conducted using 22 items shared by different test forms.

Findings

A series of implementations and revisions resulted in a 50-question test, the Environmental Stewardship Reasoning and Knowledge Assessment (ESRKA), which showed good reliability (0.83). A comparative analysis provided evidence of the validity of the instrument. Results from a small sample of students showed that second-year students generally performed better on the 22 items than incoming first-year students. Those taking the assessment as second-year students, 18 months after their initial assessment, scored significantly higher on the 22 items by about 10.4 percentage points (0.61 standard deviation units, t68 = 6.23, p < 0.0001).

Research limitations/implications

Because of the small sample size and revision of the items, the analysis of student learning is only exploratory.

Originality/value

The learning outcomes and validated assessment instrument may be used either in whole or part by other institutions. The approach to measure changes in students’ environmental stewardship reasoning and knowledge abilities as cohorts over time could assist universities in tracking environmental stewardship learning and could inform strategic implementation of learning opportunities through the curriculum, as well as through other student learning experiences.
Using role-playing games to broaden engineering education
Authors: McConville Jennifer R. , Rauch Sebastien , Helgegren Ida , Kain Jaan-Henrik
Published: April 2017

Purpose

In today’s complex society, there is an increasing demand to include a wider set of skills in engineering curricula, especially skills related to policy, society and sustainable development. Role-playing and gaming are active learning tools, which are useful for learning relationships between technology and society, problem solving in complex situations and communication. However, use of these learning methods in higher education, and in engineering particularly, is limited. The purpose of this study was to test the effectiveness of a role-playing game for learning about complexities related to sustainable water and sanitation management within a civil engineering curriculum.

Design/methodology/approach

The game has been used during three consecutive years in a Masters’ level course. Surveys and course evaluations were used to evaluate the effectiveness of this method from both teacher and student perspectives.

Findings

The results show that students gained knowledge on complex subjects, and both teachers and students had positive experiences. Better integration of the game within the rest of the course could strengthen its effectiveness.

Originality/value

The experiences gained from this study should assist others in the development and use of such active learning techniques in higher education.