bluuebunny/crossref_metadata_2025 huggingface dataset:
Accurate registration of 3D time-lapse microscopy images
Authors: Kahaki Seyed M. M. , Wang Shih-Luen , Stepanyants Armen
Published: October 2018

In vivo imaging experiments often require automated detection and tracking of changes in the specimen. This problem, however, can be hindered by variations in the position and orientation of the specimen relative to the microscope, as well as by linear and nonlinear deformations. Here, we present a feature-based registration method, coupled with translation, rigid, affine, and B-spline transformations, designed to address these issues in 3D time-lapse microscopy images. In this method, features are detected as local intensity maxima in the source and target image stacks, and their similarity matrix is used as an input to the Hungarian algorithm to establish initial correspondences. Random Sampling Consensus algorithm is then employed to eliminate outliers. The resulting set of corresponding features is used to determine the optimal transformations. Accuracy of the proposed algorithm was tested on fluorescently labeled axons imaged over a 48- day period with a two-photon laser scanning microscope. For this, multiple axons in individual stacks of images were traced semi-manually in 3D, and the distances between the corresponding traces were measured before and after the registration. The results show that there is a progressive improvement in the registration accuracy with increasing complexity of the transformations. In particular, an accuracy of less than 1 voxel (0.26 μm) was achieved with a regularized B-spline transformation. To illustrate the utility of the proposed method, registered images were used to automatically track synaptic boutons on axons over the entire duration of the experiment, yielding 99% precision and recall.
Mitochondrial type II NADH dehydrogenase ofPlasmodium falciparumis dispensable and not the functional target of putative NDH2 quinolone inhibitors
Authors: Ke Hangjun , Ganesan Suresh M. , Dass Swati , Morrisey Joanne M. , Pou Sovitj , Nilsen Aaron , Riscoe Michael K. , Mather Michael W. , Vaidya Akhil B.
Published: October 2018

The battle against malaria has been substantially impeded by the recurrence of drug resistance inPlasmodium falciparum, the deadliest human malaria parasite. To counter the problem, novel antimalarial drugs are urgently needed, especially those that target unique pathways of the parasite, since they are less likely to have side effects. The mitochondrial type II NADH dehydrogenase ofP. falciparum, PfNDH2 (PF3D7_0915000), has been considered a good prospective antimalarial drug target for over a decade, since malaria parasites lack the conventional multi-subunit NADH dehydrogenase, or Complex I, present in the mammalian mitochondrial electron transport chain (mtETC). Instead, Plasmodium parasites contain a single subunit NDH2, which lacks proton pumping activity and is absent in humans. A significant amount of effort has been expended to develop PfNDH2 specific inhibitors, yet the essentiality of PfNDH2 has not been convincingly verified. Herein, we knocked out PfNDH2 inP. falciparumvia a CRISPR/Cas9 mediated approach. Deletion of PfNDH2 does not alter the parasite’s susceptibility to multiple mtETC inhibitors, including atovaquone and ELQ-300. We also show that the antimalarial activity of the fungal NDH2 inhibitor HDQ and its new derivative CK-2-68 is due to inhibition of the parasite cytochromebc1complex rather than PfNDH2. These compounds directly inhibit the ubiquinol-cytochromecreductase activity of the malarialbc1complex. Our results call into question the validity of PfNDH2 as an antimalarial drug target.

Importance

For a long time, PfNDH2 has been considered an attractive antimalarial drug target. However, the conclusion that PfNDH2 is essential was based on preliminary and incomplete data. Here we generate a PfNDH2 KO (knockout) parasite in the blood stages ofPlasmodium falciparum, showing that the gene is not essential. We also show that previously reported PfNDH2-specific inhibitors kill the parasites primarily via targeting the cytochromebc1complex, not PfNDH2. Overall, we provide genetic and biochemical data that help to resolve a long-debated issue in the field regarding the potential of PfNDH2 as an antimalarial drug target.
AIDE: annotation-assisted isoform discovery with high precision
Authors: Li Wei Vivian , Li Shan , Tong Xin , Deng Ling , Shi Hubing , Li Jingyi Jessica
Published: October 2018

Genome-wide accurate identification and quantification of full-length mRNA isoforms is crucial for investigating transcriptional and post-transcriptional regulatory mechanisms of biological phenomena. Despite continuing efforts in developing effective computational tools to identify or assemble full-length mRNA isoforms from second-generation RNA-seq data, it remains a challenge to accurately identify mRNA isoforms from short sequence reads due to the substantial information loss in RNA-seq experiments. Here we introduce a novel statistical method, AIDE (Annotation-assisted Isoform DiscovEry), the first approach that directly controls false isoform discoveries by implementing the testing-based model selection principle. Solving the isoform discovery problem in a stepwise and conservative manner, AIDE prioritizes the annotated isoforms and precisely identifies novel isoforms whose addition significantly improves the explanation of observed RNA-seq reads. We evaluate the performance of AIDE based on multiple simulated and real RNA-seq datasets followed by a PCR-Sanger sequencing validation. Our results show that AIDE effectively leverages the annotation information to compensate the information loss due to short read lengths. AIDE achieves the highest precision in isoform discovery and the lowest error rates in isoform abundance estimation, compared with three state-of-the-art methods Cufflinks, SLIDE, and StringTie. As a robust bioinformatics tool for transcriptome analysis, AIDE will enable researchers to discover novel transcripts with high confidence.
Transection of the ventral hippocampal commissure impairs spatial reference but not contextual or spatial working memory
Authors: Jordan Jake T. , Tong Yi , Pytte Carolyn L.
Published: October 2018

Plasticity is a neural phenomenon in which experience induces long-lasting changes to neuronal circuits and is at the center of most neurobiological theories of learning and memory. However, too much plasticity is maladaptive and must be balanced with substrate stability. Area CA3 of the hippocampus is lateralized with the left hemisphere dominant in plasticity and the right specialized for stability. Left and right CA3 project bilaterally to CA1; however, it is not known whether this downstream merging of lateralized plasticity and stability is functional. We hypothesized that interhemispheric integration of input from these pathways is essential for integrating spatial memory stored in the left CA3 with spatial working memory facilitated by the right CA3. To test this, we severed interhemispheric connections between the left and right hippocampi in mice and assessed learning and memory. Despite damage to this major hippocampal fiber tract, hippocampus-dependent spatial working memory and short- and long-term memory were both spared. However, tasks that required the integration of information retrieved from memory with ongoing spatial working memory and navigation were impaired. We propose that one function of interhemispheric communication in the mouse hippocampus is to integrate lateralized processing of plastic and stable circuits to facilitate memory-guided spatial navigation.
Single-cell RNA-seq identifies a reversible epithelial-mesenchymal transition in abnormally specified epithelia of p63 EEC syndrome
Authors: Soares Eduardo , Xu Quan , Li Qingqing , Qu Jieqiong , Zheng Yuxuan , Raeven Henriette H. M. , Brandao Karina , Petit Isabelle , van den Akker Willem M.R. , Aberdam Daniel , Tang Fuchou , Zhou Huiqing
Published: October 2018

Mutations in transcription factor p63 are associated with developmental disorders that manifest defects in stratified epithelia including the epidermis. The underlying cellular and molecular mechanism is however not yet understood. We established an epidermal commitment model using human induced pluripotent stem cells (iPSCs) and characterized differentiation defects of iPSCs derived from ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome patients carrying p63 mutations. Transcriptome analyses revealed distinct step-wise cell fate transitions during epidermal commitment; from multipotent simple epithelium to basal stratified epithelia, and ultimately to the mature epidermal fate. Differentiation defects of EEC iPSCs caused by mutant p63 occurred during the specification switch from the simple epithelium to the basal stratified epithelial fate. Single-cell transcriptome and pseudotime analyses identified signatures of embryonic epithelial-mesenchymal transition (EMT) associated with the deviated commitment route of EEC iPSCs. Repressing mesodermal activation reversed the EMT and enhanced epidermal commitment. Our findings demonstrate that p63 is required for specification of stratified epithelia, probably by repressing embryonic EMT during epidermal commitment. This study provides insights into disease mechanisms underlying stratified epithelial defects caused by p63 mutations and suggests potential therapeutic strategies for the disease.

Significance statement

Mutations in p63 cause several developmental disorders with defects of epithelial related organs and tissues including the epidermis. Our study is to dissect the unknown cellular and molecular pathomechanism. We utilized human induced pluripotent stem cells (iPSCs) derived from ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome patients carrying p63 mutations and studied transcriptome changes during differentiation of these cells to epidermal cells. Our analyses showed that the specification of the proper epithelial cell fate was affected by p63 EEC mutations, with an abnormal embryonic epithelial-mesenchymal transition (EMT). Repressing mesodermal activation reversed the EMT and enhanced epidermal commitment. This study provides insights into disease mechanisms associated with p63 mutations and suggests potential therapeutic strategies.
Genetic variability in response to Aβ deposition influences Alzheimer’s risk
Authors: Salih Dervis A. , Bayram Sevinc , Guelfi Manuel S. , Reynolds Regina , Shoai Maryam , Ryten Mina , Brenton Jonathan , Zhang David , Matarin Mar , Botia Juan , Shah Runil , Brookes Keeley , Guetta-Baranes Tamar , Morgan Kevin , Bellou Eftychia , Cummings Damian M. , Hardy John , Edwards Frances A. , Escott-Price Valentina
Published: October 2018

Genetic analysis of late-onset Alzheimer’s disease risk has previously identified a network of largely microglial genes that form a transcriptional network. In transgenic mouse models of amyloid deposition we have previously shown that the expression of many of the mouse orthologs of these genes are co-ordinately up-regulated by amyloid deposition. Here we investigate whether systematic analysis of other members of this mouse amyloid-responsive network predicts other Alzheimer’s risk loci. This statistical comparison of the mouse amyloid-response network with Alzheimer’s disease genome-wide association studies identifies 5 other genetic risk loci for the disease (OAS1, CXCL10, LAPTM5, ITGAM and LILRB4). This work suggests that genetic variability in the microglial response to amyloid deposition is a major determinant for Alzheimer’s risk.

One Sentence Summary

Identification of 5 new risk loci for Alzheimer’s by statistical comparison of mouse Aβ microglial response with gene-based SNPs from human GWAS
Distinct waking states for strong evoked responses in primary visual cortex and optimal visual detection performance
Authors: Neske Garrett T. , McCormick David A.
Published: October 2018

Variability in cortical neuronal responses to sensory stimuli and in perceptual decision making performance is substantial. Moment-to-moment fluctuations in waking state or arousal can account for much of this variability. Yet, the nature of this variability across the full spectrum of waking states is often not completely characterized, leaving the characteristics of the optimal state for sensory processing unresolved. Using pupillometry in concert with extracellular multiunit and intracellular whole-cell recordings, we found that the magnitude and reliability of visually evoked responses in primary visual cortex (V1) of awake, passively behaving male mice increase as a function of arousal and are largest during sustained locomotion periods. During these high-arousal, sustained locomotion periods, cortical neuronal membrane potential was at its most depolarized and least variable. Contrastingly, behavioral performance of mice on two distinct visual detection tasks was generally best at a range of intermediate arousal levels, but worst during locomotion. These results suggest that large, reliable responses to visual stimuli in V1 occur at a distinct arousal level from that associated with optimal visual detection performance. Our results clarify the relation between neuronal responsiveness and the continuum of waking states, and suggest new complexities in the relation between primary sensory cortical activity and behavior.
Reconstitution of the equilibrium state of dynamic actin networks
Authors: Manhart Angelika , Icheva Aleksandra , Guerin Christophe , Klar Tobbias , Boujemaa-Paterski Rajaa , Thery Manuel , Blanchoin Laurent , Mogilner Alex
Published: October 2018

Principles of regulation of actin network dimensions, fundamentally important for cell functions, remain unclear. We studied in vitro and in silico the effect of key parameters, actin density, ADF/Cofilin concentration and network width on the network length. In the presence of ADF/Cofilin, networks reached equilibrium and became globally treadmilling. At the trailing edge, the network disintegrated into large fragments. A mathematical model predicts the network length as a function of width, actin and ADF/Cofilin concentrations. Local depletion of ADF/Cofilin by binding to actin is significant, leading to wider networks growing longer. A single rate of breaking network nodes, proportional to ADF/Cofilin density and inversely proportional to the square of the actin density, can account for the disassembly dynamics. Selective disassembly of heterogeneous networks by ADF/Cofilin controls steering during motility. Our results establish general principles on how the dynamic equilibrium state of actin network emerges from biochemical and structural feedbacks.
Distinctive interaction between cognitive networks and the visual cortex in early blind individuals
Authors: Abboud Sami , Cohen Laurent
Published: October 2018

In early blind individuals, brain activation by a variety of non-perceptual cognitive tasks extends to the visual cortex, while in the sighted it is restricted to supramodal association areas. We hypothesized that such activation results from the integration of different sectors of the visual cortex into typical task-dependent networks. We tested this hypothesis with fMRI in blind and sighted subjects using tasks assessing speech comprehension, incidental long-term memory and both verbal and non-verbal executive control, in addition to collecting resting-state data. All tasks activated the visual cortex in blind relative to sighted subjects, which enabled its segmentation according to task sensitivity. We then assessed the unique brain-scale functional connectivity of the segmented areas during resting state. Language-related seeds were preferentially connected to frontal and temporal language areas; the seed derived from the executive task was connected to the right dorsal frontoparietal executive network; the memory-related seed was uniquely connected to mesial frontoparietal areas involved in episodic memory retrieval. Thus, using a broad set of language, executive, and memory tasks in the same subjects, combined with resting state connectivity, we demonstrate the selective integration of different patches of the visual cortex into brain-scale networks with distinct localization, lateralization, and functional roles.
Correlation of occludin protein mobility with paracellular leak pathway permeability in renal epithelia
Authors: Axis Josephine , Kolb Alexander L. , Bacallao Robert L. , Amsler Kurt
Published: October 2018

Studies have demonstrated regulation of the epithelial paracellular permeability barrier, the tight junction, by a variety of stimuli. Recent studies have reported a correlation between changes in paracellular permeability, particularly paracellular permeability to large solutes (leak pathway), and mobility of the tight junction protein, occludin, in the plane of the plasma membrane. This had led to the hypothesis that changes in occludin protein mobility are causative for changes in paracellular permeability. Using a renal epithelial cell model system, MDCK, we examined the effect of various manipulations on both leak pathway permeability, monitored as the paracellular movement of a fluorescent molecule (calcein), and occludin protein mobility, monitored through fluorescence recovery after photobleaching. Our results indicate that knockdown of the associated tight junction protein, ZO-1, increases baseline leak pathway permeability, whereas, knockdown of the related tight junction protein, ZO-2, does not alter baseline leak pathway permeability. Knockdown of either ZO-1 or ZO-2 decreases the rate of movement of occludin protein but only knockdown of ZO-2 protein alters the percent of occludin protein that is mobile. Further, treatment with hydrogen peroxide increases leak pathway permeability in wild type MDCK cells and in ZO-2 knockdown MDCK cells but not in ZO-1 knockdown MDCK cells. This treatment decreases the rate of occludin movement in all three cell lines but only alters the mobile fraction of occludin protein in ZO-1 knockdown MDCK cells. Finally, we examined the effect of renal ischemia/reperfusion injury on occludin protein mobility in vivo.

Ischemia/reperfusion injury both increased the rate of occludin mobility and increased the fraction of occludin protein that is mobile. These results indicate that, at least in our cell culture and in vivo model systems, there is no consistent correlation between paracellular leak pathway permeability and occludin protein mobility.
Absence of general rules governing molluscan body-size response to climatic fluctuation during Cenozoic
Authors: Chattopadhyay Debarati , Chattopadhyay Devapriya
Published: October 2018

Body size is a key factor in dictating the fate of interaction between an organism and its surrounding environment. A negative temperature-size relationship (TSR) has been suggested as one of the universal responses to climatic warming. It is also predicted that groups with narrow latitudinal range, tropical affinity and higher body size, would show higher sensitivity to climatic fluctuation. Moreover, because of the difference in thermal sensitivity, it is also expected that the response to climatic fluctuation would be different between epifaunal and infaunal groups. To confirm the generality of these relationship among marine families, we compiled the relationship between body-size and global temperature trends over Cenozoic using a database of marine benthic molluscs of class gastropoda and bivalvia resolved to temporal stages. We evaluated the dependence of climate induced body-size response to the existing size and latitudinal spread via correlating the first-difference correlation coefficient of temperature-size (ρ1st(size-temp)) with maximum size and latitudinal spread of family respectively. Cenozoic record of this highly diverse group does not show any signature of TSR for molluscan class or for any other regional, ecological groups during the past 66My long climatic fluctuation. We did not find any evidence supporting heightened response to climatic fluctuation in groups with limited latitudinal spread or with large body-size. The tropical species did not show significant difference in their body-size response in comparison to temperate species. It also shows lack of any difference in response between ecological groups of molluscs with varying substrate relationship and hence, refutes the predicted variation due to difference in thermal specialization. Although a negative correlation between maximum latitudinal spread and ρ1st(size-temp)is observed for infaunal families, it is not statistically significant. Our results highlight the limited validity of “universal rules” in explaining the climate induced morphological response of marine communities in deep time and underscores the complexity in generalizing the biotic outcome of future climatic fluctuation.
Estimation of auditory steady-state responses based on the averaging of independent EEG epochs
Authors: Prado-Gutierrez Pavel , Martínez-Montes Eduardo , Weinstein Alejandro , Zañartu Matías
Published: October 2018

The amplitude of the auditory steady-state responses (ASSRs) generated in the brainstem exponentially decreases over the averaging of subsequent EEG epochs. This behavior is partially due to the adaptation of the auditory response to the continuous and monotonous stimulation. We analyzed the potential clinical relevance of the ASSR adaptation. Specifically, we compare the ASSR amplitude computed in two conditions: (1) when the auditory responses -embedded in the EEG epochs that are averaged in the estimation procedure- are influenced by the previous stimulation; and (2) when they are independent of the previous stimulation. ASSR were elicited in eight anesthetized adult rats by 8-kHz tones, modulated in amplitude at 115 Hz. ASSR amplitudes were computed using three averaging methods (standard, weighted and sorted averaging). We evaluated the ASSR amplitude as a function of sub-set of epochs selected for the averaging and the improvement in the ASSR detection resulting from averaging independent epochs. Due to adaptation, the ASSR amplitude computed by averaging dependent EEG epochs relied upon the averaging method. Lower ASSR amplitudes were obtained as EEG segments containing unadapted responses were systematically excluded from the averaging. In the absence of EEG artifacts, the ASSR amplitudes did not depend on the averaging method when they were computed from independent EEG epochs. The amplitude of independent ASSRs were up to 35% higher than those obtained by processing dependent EEG segments. Extracting the ASSR amplitude from independent epochs halved the number of EEG segments needed to be averaged to achieve the maximum detection rate of the response. Acquisition paradigm based on a discrete acoustic stimulation (in which segments of AM-sounds of several seconds in length are presented after a given inter stimulus interval), in combination with appropriated averaging methods might increase the accuracy of audiological tests based on ASSRs.
Inhibition of platelet function by targeting the platelet cytoskeleton via the LIMK-signaling pathway
Authors: Antonipillai Juliana , Rigby Sheena , Bassler Nicole , Peter Karlheinz , Bernard Ora
Published: October 2018

Actin is highly abundant in platelets, and platelet function is dependent on actin structures. Actin filaments are dynamic structures involved in many cellular processes including platelet shape changes and adhesion. The actin cytoskeleton is tightly regulated by actin-binding proteins, which include the members of the actin depolymerising factor (ADF)/cofilin family. LIM kinase (LIMK) and slingshot phosphatase (SSH-1L) regulate actin dynamics by controlling the binding affinity of ADF/cofilin towards actin. We hypothesised that inhibition of LIMK activity may prevent the changes in platelet shape during their activation and therefore their function by controlling the dynamics of Factin. Therefore, inhibition of LIMK activity may represent an attractive new strategy to control and inhibit platelet function; particularly the formation of stable platelet aggregates and thus stable thrombi.
Thermal acclimation of photosynthetic activity and Rubisco content in two hybrid poplar clones
Authors: Benomar Lahcen , Moutaoufik Mohamed. Taha , Elferjani Raed , Isabel Nathalie , DesRochers Annie , Guellab Ahmed El , Khlifa Rim , Idrissi Hassania Lala Amina
Published: October 2018

The mechanistic bases of thermal acclimation of net photosynthetic rate (An) are still difficult to discern and empirical research remains limited, particularly for hybrid poplar. In the present study, we examined the contribution of a number of biochemical and biophysical traits on thermal acclimation ofAnfor two hybrid poplar clones. We grew cuttings ofPopulus maximowiczii×Populus nigra(M×N) andPopulus maximowiczii×Populus balsamifera(M×B) clones under two day/night temperature of 23°C/18°C and 33°C /27°C and under low and high soil nitrogen level. After 10 weeks, we measured leaf RuBisCO and RuBisCO activase (RCA) amounts and the temperature response ofAn, dark respiration (Rd), stomatal conductance, (gs), maximum carboxylation rate of CO2(Vcmax) and photosynthetic electron transport rate (J). Results showed that a 10°C increase in growth temperature resulted in a shift in thermal optimum (Topt) ofAnof 6.2±1.6 °C and 8.0±1.2 °C for clone M×B and M×N respectively, and an increasedAnandgsat the growth temperature for clone M×B but not M×N. RuBisCO amount was increased by N level but was insensitive to growth temperature whileRCAamount and the ratio of its short to long isoform was stimulated by warm condition for clone M×N and at low N for clone M×B. The activation energy ofVcmaxandJdecreased under warm condition for clone M×B and remain unchanged for clone M×N. Our study demonstrated the involvement of bothRCA, activation energy ofVcmaxand stomatal conductance in thermal acclimation ofAn.
Description of Cranial Elements and Ontogenetic Change within Tropidolaemus wagleri (Serpentes: Crotalinae)
Authors: Hill Nicolette
Published: October 2018

Tropidolaemus wagleri is a species of Asian pitviper with a geographic range including Thailand, Vietnam, Malaysia, Singapore, Bruniei, parts of Indonesia, and the Philippines. Tropidolaemus is a member of the Crotalinae subfamily, within Viperidae. The genus Tropidolaemus includes five species, and was once included within the genus Trimeresurus. While some osteologic characteristics have been noted a comprehensive description of cranial elements has not been produced for T. wagleri. An in-depth description of the cranial skeleton of Tropidolaemus wagleri lays the foundation for future projects to compare and contrast other taxa within Crotalinae and Viperidae. The chosen reference specimen was compared to the presumed younger specimens to note any variation in ontogeny. The study here provides a comprehensive description of isolated cranial elements as well as a description of ontogenetic change within the specimens observed. This study contributes to the knowledge of osteological characters in T. wagleri and provides a foundation for a long term project to identify isolated elements in the fossil record.
The mitochondrial copper chaperone COX11 plays an auxiliary role in the defence against oxidative stress
Authors: Radin Ivan , Gey Uta , Kost Luise , Steinebrunner Iris , Rödel Gerhard
Published: October 2018

COX11, a protein anchored in the inner mitochondrial membrane, was originally identified as a copper chaperone delivering Cu+ to the cytochrome c oxidase of the respiratory chain. Here, we present evidence that this protein is also involved in the defence against reactive oxygen species. Quantitative PCR analyses in the model plant Arabidopsis thaliana revealed that the level of AtCOX11 mRNA rises under oxidative stress. The unexpected result that AtCOX11 knock-down lines contained less ROS than the wild-type can possibly be explained by the impaired oxidative phosphorylation, resulting in less respiration-dependent ROS formation. Similarly, we observed that yeast Saccharomyces cerevisiae ScCOX11 null mutants produced less ROS than wild-type cells. However, when exposed to oxidative stress, yeast strains overexpressing ScCOX11 or AtCOX11 showed lower ROS levels compared with the control indicating a ROS-detoxifying effect of the COX11 proteins. The additive effect on ROS sensitivity upon deletion of ScCOX11 in addition to the known ROS scavenger gene SOD1 encoding superoxide dismutase 1 corroborates the oxidative stress-relieving function of ScCOX11. Moreover, yeast strains overexpressing soluble versions of either AtCOX11 or ScCOX11 became more resistant against oxidative stress. The importance of three conserved cysteines for the ROS scavenger function became apparent after their deletion that resulted in the loss of ROS resistance. Further studies of strains producing COX11 proteins with individually mutated cysteines indicate that the formation of disulphide bridges might be the underlying mechanism responsible for the antioxidative activity of COX11 proteins. Both AtCOX11 and ScCOX11 apparently partake in oxidative stress defence by directly or indirectly exploiting the redox capacity of their cysteine residues.
Rigorous calculations and synchrotron radiation measurements of diffraction efficiencies for tender X-ray lamellar gratings: conical versus classical diffraction
Authors: Goray Leonid , Jark Werner , Eichert Diane
Published: October 2018

When reflection gratings are operated at grazing incidence in the extreme off-plane configuration and the incident beam trajectory is parallel to the grooves, the diffraction into the first order can be more efficient than in the classical orientation. This situation is referred to as the conical diffraction case. In the classical configuration the grooves are perpendicular to the incident beam and thus an efficiency-reducing shadowing effect will be observed at very grazing angles. It was recently shown that a laminar grating could provide symmetric and relatively high efficiencies in conical diffraction for diffraction even of photons with large energies of the order of 4 and 6 keV. For photon energies in the tender X-ray range, accurate computing tools for the calculation of diffraction efficiencies from gratings with simple coatings have not been available. Promising results for this spectral range now require the development of tools for modelling the diffraction efficiency expected in optical instrumentation, in which the provision of high efficiency in the indicated spectral range is mandatory. This is the case when weak sources are to be investigated, like in space science. In this study it will be shown that scalar calculations are not appropriate for this purpose, while newly introduced rigorous calculations based on the boundary integral equation method, implemented in the PCGrate
® code, can provide predictions that are in agreement with observed diffraction efficiencies. The agreement is achieved by modelling the exact surface profile. This applies for both the conical diffraction configuration and for the classical in-plane configuration, in which a significantly lower efficiency was obtained. Even though the profile of the presented grating was not perfect, but significantly distorted, the calculations show that efficiency-wise the structure provided already more than 75% of the ideally expected efficiency for conical diffraction. This is a very promising result for further optimization of diffraction gratings for use in the tender X-ray range.
Flexible sample cell for real-time GISAXS, GIWAXS and XRR: design and construction
Authors: Berlinghof M. , Bär C. , Haas D. , Bertram F. , Langner S. , Osvet A. , Chumakov A. , Will J. , Schindler T. , Zech T. , Brabec C. J. , Unruh T.
Published: October 2018

Since the properties of functional materials are highly dependent on their specific structure, and since the structural changes, for example during crystallization, induced by coating and annealing processes are significant, the study of structure and its formation is of interest for fundamental and applied science. However, structure analysis is often limited to ex situ determination of final states due to the lack of specialized sample cells that enable real-time investigations. The lack of such cells is mainly due to their fairly complex design and geometrical restrictions defined by the beamline setups. To overcome this obstacle, an advanced sample cell has been designed and constructed; it combines automated doctor blading, solvent vapor annealing and sample hydration with real-time grazing-incidence wide- and small-angle scattering (GIWAXS/GISAXS) and X-ray reflectivity (XRR). The sample cell has limited spatial requirements and is therefore widely usable at beamlines and laboratory-scale instruments. The cell is fully automatized and remains portable, including the necessary electronics. In addition, the cell can be used by interested scientists in cooperation with the Institute for Crystallography and Structural Physics and is expandable with regard to optical secondary probes. Exemplary research studies are presented, in the form of coating of P3HT:PC61PM thin films, solvent vapor annealing of DRCN5T:PC71BM thin films, and hydration of supported phospholipid multilayers, to demonstrate the capabilities of the in situ cell.
Co-designed of network scheduling and sliding mode control for underwater shuttle based on adaptive genetic algorithm
Authors: Li Zeyu , Liu Weidong , Li Le , Liu Zhi , Zhang Feihu
Published: October 2018

Purpose

Underwater shuttle is widely used in scenarios of deep sea transportation and observation. As messages are transmitted via the limited network, high transmission time-delay often leads to information congestion, worse control performance and even system crash. Moreover, due to the nonlinear issues with respect to shuttle’s heading motion, the delayed transmission also brings extra challenges. Hence, this paper aims to propose a co-designed method, for the purpose of network scheduling and motion controlling.

Design/methodology/approach

First, the message transmission scheduling is modeled as an optimization problem via adaptive genetic algorithm. The initial transmission time and the genetic operators are jointly encoded and adjusted to balance the payload in network. Then, the heading dynamic model is compensated for the delayed transmission, in which the parameters are unknown. Therefore, the adaptive sliding mode controller is designed to online estimate the parameters, for enhancing control precision and anti-interference ability. Finally, the method is evaluated by simulation.

Findings

The messages in network are well scheduled and the time delay is thus reduced, which increases the quality of service in network. The unknown parameters are estimated online, and the quality of control is enhanced. The control performance of the shuttle control system is thus increased.

Originality/value

The paper is the first to apply co-design method of message scheduling and attitude controlling for the underwater unmanned vehicle, which enhaces the control performance of the network control system.
Philosophy of language and accounting
Authors: Alexander David , de Brébisson Hélène , Circa Cristina , Eberhartinger Eva , Fasiello Roberta , Grottke Markus , Krasodomska Joanna
Published: October 2018

Purpose

Accounting practices vary not only across firms, but also across countries, reflecting the respective legal and cultural background. Attempts at harmonization therefore continue to be rebuffed. The purpose of this paper is to argue that different wordings in national laws, and different interpretations of similar wordings in national laws, can be explained by taking recourse to the philosophy of language, referring particularly to Searle and Wittgenstein.

Design/methodology/approach

The example of the substance over form principle, investigated in seven countries, is particularly suitable for this analysis. It is known in all accounting jurisdictions, but still has very different roots in different European countries, with European and international influences conflicting, which is reflected in the different wording of the principle from one country to the next, and the different socially constructed realities associated with those wordings.

Findings

This paper shows that, beyond accounting practices, the legal and cultural background of a country affects the wording of national law itself. The broad conclusion is that different socially constructed realities might tend to resist any attempt at harmonized socially constructed words.

Originality/value

The paper contributes to the debate surrounding the possible homogenization of accounting regulations, illustrating the theory of the social construction of both “reality” and “language” on the specific application of one common principle to various Member State environments.
Suppression of nonlinear aeroelastic vibrations by learned neural network controller
Authors: Dul Franciszek
Published: October 2018

Purpose

The purpose of the paper is to analyze the active suppression of the aeroelastic vibrations of ailerons with strongly nonlinear characteristics by neural network/reinforcement learning (NN/RL) control method and comparing it with the classic robust methods of suppression.

Design/methodology/approach

The flexible wing and aileron with hysteresis nonlinearity is treated as a plant-controller system and NN/RL and robust controller are used to suppress the nonlinear aeroelastic vibrations of aileron. The simulation approach is used for analyzing the efficiency of both types of methods in suppressing of such vibrations.

Findings

The analysis shows that the NN/RL controller is able to suppress the nonlinear vibrations of aileron much better than linear robust method, although its efficiency depends essentially on the NN topology as well as on the RL strategy.

Research limitations/implications

Only numerical analysis was carried out; thus, the proposed solution is of theoretical value, and its application to the real suppression of aeroelastic vibrations requires further research.

Practical implications

The work shows the NN/RL method has a great potential in improving suppression of highly nonlinear aeroelastic vibrations, opposed to the classical robust methods that probably reach their limits in this area.

Originality/value

The work raises the questions of controllability of the highly nonlinear aeroelastic systems by means of classical robust and NN/RL methods of control.
Bending and vibration analysis of skew sandwich plate
Authors: Katariya Pankaj V. , Panda Subrata Kumar , Mahapatra Trupti Ranjan
Published: October 2018

Purpose

The purpose of this paper is to develop a general mathematical model for the evaluation of the bending and vibration responses of the skew sandwich composite plate using higher-order shear deformation theory. The sandwich structural components are highly preferable in modern engineering application because of their desirable structural advantages despite the manufacturing and analysis complexities. The present model is developed to solve the bending and vibration problem of the skew sandwich composite plate with adequate accuracy numerically in the absence of the experimental analysis.

Design/methodology/approach

The skew sandwich composite plate structure is modelled in the present analysis by considering laminated face sheet in conjunction with isotropic and/or orthotropic core numerically with the help of the higher-order mathematical model. Further, the responses are computed numerically with the help of in-house computer code developed in matrix laboratory (MATLAB) environment in conjunction with finite element (FE) steps. The system governing equations are derived via variational technique for the computation of the static and the frequency responses.

Findings

The skew sandwich composite plate is investigated using the higher-order kinematic model where the transverse displacement through the thickness is considered to be linear. The convergence and the validation study of the bending and the frequency values of the sandwich structure indicate the necessary accuracy. Further, the current model has been used to highlight the applicability of the higher-order kinematics for the evaluation of the sandwich structural responses (frequency and static deflections) for different design parameters.

Originality/value

In the present paper, the bending and the vibration responses of the skew sandwich composite plate are analysed numerically using the equivalent single-layer higher-order kinematic theory for the isotropic and the orthotropic core numerically with the help of isoparametric FE steps. Finally, it is understood that the present model is capable of solving the sandwich structural responses with less computation cost and adequate accuracy.
An empirical study of biological scientists’ article sharing through ResearchGate
Authors: Kim Youngseek
Published: October 2018

Purpose

The purpose of this paper is to investigate how attitudinal, normative and control beliefs influence scientists’ article sharing through ResearchGate.

Design/methodology/approach

A survey method was employed to examine a research model of scientists’ article sharing through ResearchGate. A total of 264 survey responses from biological scientists in the USA were used to evaluate the research model by using partial least square based structural equation modeling.

Findings

The results showed that scientists’ attitudinal beliefs (i.e. perceived relationship, reputation and risk), normative beliefs (i.e. subjective norm, perceived academic culture and community norm of article sharing) and control belief (i.e. perceived ease of use) all significantly affect their attitudes toward article sharing and article sharing intentions through ResearchGate.

Research limitations/implications

The theory of planned behavior (TPB) was used to develop the research model, and the specific research constructs from prior literature were incorporated in the model. The TPB and related research constructs nicely explained biological scientists’ article sharing through ResearchGate.

Practical implications

This study suggests that academic libraries can better promote their scientists’ article sharing through digital platforms such as institutional repositories as well as scholarly social media. This can be achieved by emphasizing its benefits, including potential relationships or collaborations, positive academic reputation and community norms of article sharing, and by decreasing scientists’ concerns about copyright infringements and effort expectancy involved in article sharing.

Originality/value

As one of the initial studies in scientists’ article sharing through ResearchGate, this study provides a holistic picture of how attitudinal, normative and control beliefs all affect scientists’ article sharing through ResearchGate.
Psychological contract and employee attitudes
Authors: Zhang Yuchao , Ren Ting , Li Xuanye
Published: October 2018

Purpose

This paper aims to investigate the Chinese employment relationship under the framework of psychological contracts. The authors explored the effects of firm ownership (in terms of state-owned and private enterprises) and employment type (in terms of permanent and temporary employees) on employee perceptions of psychological contract. In addition, the associations between fulfilled psychological contract and various dimensions of employee attitudes were examined.

Design/methodology/approach

The authors adopted a questionnaire as the primary instrument to investigate the impact of firm ownership and employment type on psychological contract perceptions and outcomes. The analysis was based on a Chinese sample of a size of 363 employees.

Findings

The results indicate that state-owned employees overall reported fewer promises (employer under-obligation promised psychological contract), while private employees tended to have more promises (mutual high obligation, employer over-obligation and quasi-spot obligation promise-based psychological contract). Permanent employees reported high fulfillment (employer over-obligation, mutual high obligation and employer under-obligation fulfilled psychological contract). In contrast, temporary employees presented many promises (mutual high obligation promised psychological contract) and low fulfillment (quasi-spot fulfilled psychological contract). In general, firm ownership had weak effects on permanent and temporary employees’ perceptions of promise-based psychological contract, but no significant influence on fulfillment-based psychological contract. Moreover, psychological contract fulfillment was positively related to employees’ fairness perception and job satisfaction, while negatively related to the intention to quit. The authors failed to find comprehensive statistical support for the moderating effects of firm ownership or employment type.

Originality/value

The study contributes to the literature through a number of ways. First, instead of psychological contract breach, the authors use psychological contract fulfillment as a direct measure to examine the relationship between psychological contract and employees’ attitudes. Second, they investigate the effects of firm ownership on employment relationship under the psychological contract framework, enriching the institutional lens of the issue. Third, while majority of psychological contract studies concerning employment type concentrate on either permanent or temporary employees, the authors take both types into account. Fourth, they integrate perspectives of firm ownership and employment type. Finally, the authors perform the study in the Chinese context, which offers extra evidence to the body of psychological contract literature.
Constituting gender and gender equality through policy
Authors: Andersson Elias , Johansson Maria , Lidestav Gun , Lindberg Malin
Published: October 2018

Purpose

In Sweden, gender mainstreaming policies have a long political history. As part of the national gender equality strategy of the Swedish forest industry, the ten largest forestry companies committed themselves to gender mainstream their policies. Limiting the impact of policies and the agency of change, the purpose of this paper is to focus on the varied and conflicting meanings and constitution of the concepts, the problem and, in extent, the organisational realities of gender mainstreaming.

Design/methodology/approach

In both, implementation and practice, gender mainstreaming posse challenges on various levels and by analysing these documents as practical texts from the WPR-approach. This paper explores constructions of gender and gender equality and their implications on the practice and the political of gender mainstreaming in a male-dominated primary industry.

Findings

The results show that the organisations themselves were not constituted as the subject of the policy but instead some of the individuals (women). The subject position of women represented in company policy was one of lacking skills and competences and in the need of help. Not only men and the masculine norms but organisational processes and structures were also generally invisible in the material. Power and conflict were mainly absent from the understanding of gender equality. Instead, consenting ideas of gender equality were the focus. Such conceptualisations of gender equality are beneficial for all risk concealing power structures and thereby limit the political space for change.

Originality/value

By highlighting the scale of policy and the significance of organisational contexts, the results indicate how gender and gender equality are constitutive through the governing technologies of neoliberal and market-oriented ideologies in policy – emphasising the further limiting of space for structural change and politicalization within the male-dominated organisations of Swedish forest industry.