bluuebunny/crossref_metadata_2025 huggingface dataset:
The Efficiency of a Multicomponent Training for Prospective Memory Among Healthy Older Adults
Authors: Farzin Azin , Ibrahim Rahimah , Madon Zainal , Basri Hamidon
Published: March 2018

Objective

The main objective of the present trial was to evaluate the efficiency of a preventative multicomponent prospective memory training among healthy older adults.

Design

This study was a two-arm within-participants trial with 4- and 12-wk follow-ups. Allocation ratio was 1:1, and pretraining and posttraining measurements were included. A total number of 25 healthy older adults were enrolled (mean = 63.32, SD = 4.44). Participants were randomly allocated into two conditions: (a) prospective memory training: participants underwent a multicomponent prospective memory training, and (b) control: participants were not contacted during the training phase. After the training phase was finished, participants crossed over to undergo the condition they did not experience before. The differences between pretraining and posttraining measures of prospective memory, activities of daily living, negative mood (depression), and anxiety were assessed. All changes in the measurements were analyzed using general linear method. This trial is registered at https://www.isrctn.com (#ISRCTN57600070).

Results

Multicomponent prospective memory training program was significantly effective on both subjective and objective prospective memory performances among healthy older adults. Moreover, the training had significant positive effects on activities of daily living (independence) among participants. In addition, negative mood and anxiety levels were reduced after the training was finished.

Conclusions

This multicomponent prospective memory training improved prospective memory performance and activities of daily living and reduce negative mood (depression) and anxiety levels among healthy older adults.
Brain–Heart Pathways to Blood Pressure-Related Hypoalgesia
Authors: Ottaviani Cristina , Fagioli Sabrina , Mattei Eugenio , Censi Federica , Edwards Louisa , Macaluso Emiliano , Bozzali Marco , Critchley Hugo D. , Calcagnini Giovanni
Published: March 2018

Objective

High blood pressure (BP) is associated with reduced pain sensitivity, known as BP-related hypoalgesia. The underlying neural mechanisms remain uncertain, yet arterial baroreceptor signaling, occurring at cardiac systole, is implicated. We examined normotensives using functional neuroimaging and pain stimulation during distinct phases of the cardiac cycle to test the hypothesized neural mediation of baroreceptor-induced attenuation of pain.

Methods

Eighteen participants (10 women; 32.7 (6.5) years) underwent BP monitoring for 1 week at home, and individual pain thresholds were determined in the laboratory. Subsequently, participants were administered unpredictable painful and nonpainful electrocutaneous shocks (stimulus type), timed to occur either at systole or at diastole (cardiac phase) in an event-related design. After each trial, participants evaluated their subjective experience.

Results

Subjective pain was lower for painful stimuli administered at systole compared with diastole, F(1, 2283) = 4.82, p = 0.03. Individuals with higher baseline BP demonstrated overall lower pain perception, F(1, 2164) = 10.47, p < .0001. Within the brain, painful stimulation activated somatosensory areas, prefrontal cortex, cingulate cortex, posterior insula, amygdala, and the thalamus. Stimuli delivered during systole (concurrent with baroreceptor discharge) activated areas associated with heightened parasympathetic drive. No stimulus type by cardiac phase interaction emerged except for a small cluster located in the right parietal cortex.

Conclusions

We confirm the negative associations between BP and pain, highlighting the antinociceptive impact of baroreceptor discharge. Neural substrates associated with baroreceptor/BP-related hypoalgesia include superior parietal lobule, precentral, and lingual gyrus, regions typically involved in the cognitive aspects of pain experience.
IDO1 Expression Is Associated With Immune Tolerance and Poor Prognosis in Patients With Surgically Resected Esophageal Cancer
Authors: Kiyozumi Yuki , Baba Yoshifumi , Okadome Kazuo , Yagi Taisuke , Ishimoto Takatsugu , Iwatsuki Masaaki , Miyamoto Yuji , Yoshida Naoya , Watanabe Masayuki , Komohara Yoshihiro , Baba Hideo
Published: March 2018

Objectives:

To evaluate the relationship between indoleamine 2, 3-dioxygenase (IDO1) expression and tumoral immune status and clinical outcome in esophageal cancer.

Summary Background Data:

IDO1 is a primary enzyme that generates immunosuppressive metabolites such as tryptophan and kynurenine. Like the PD-1/PD-L1 pathway, IDO1 plays a major role in tumor immunology and is a potential immune-based therapeutic target.

Methods:

The expressions of IDO1, CD8 (a marker of cytotoxic T cells), FOXP3 [a marker of regulatory T cells (Treg)], and PD-L1 in 305 curatively resected esophageal cancers were evaluated by immunostaining.

Results:

Overall survival was significantly better in the IDO1 negative cases (n = 234) than in the IDO1 positive cases (n = 71) [log-rank P = 0.0041; hazard ratio (HR): 1.75; 95% confidence interval (CI): 1.12–2.67; P = 0.015]. CD8 high expression was significantly positively correlated with overall survival (log-rank P = 0.025) and low IDO1 expression (P = 0.044). The inverse correlation between CD8 and IDO1 expressions was confirmed by double immunostaining for IDO1 and CD8. Stratification based on IDO1 and CD8 expressions was also significantly associated with overall survival (log-rank P = 0.0024). In addition, the IDO1-positive group was correlated with high counts of FOXP3-positive cells (P = 0.020), but not with PD-L1 expression status (P = 0.19).

Conclusions:

IDO1 expression was associated with an unfavorable clinical outcome in esophageal cancer, supporting its role as a prognostic biomarker. Combining the IDO1 and CD8 statuses enabled further classification of the clinical outcomes of patients.
Rainer Walter Guillery. 28 August 1929—7 April 2017
Authors: Sherman S. Murray
Published: March 2018

Rainer (Ray) Guillery was a remarkably productive neuroscientist and as such left an indelible mark on the field, both in terms of his direct contributions and also through his success at mentoring and nurturing young scholars who went on to successful careers of their own. Ray's work profoundly advanced our understanding of the related fields of development and thalamocortical functioning; his work was highly imaginative and insightful; and he was a cherished colleague and role model for his many former students and friends in the field. Ray's scholarly efforts were carried out on three continents. He trained initially in London and, after serving on the faculties at the Universities of Wisconsin and Chicago in the United States, he returned to England at the University of Oxford. After retiring from his Oxford post, he went back as a visiting scholar to the University of Wisconsin, and then moved to a post at the University of Marmara in Turkey, which is located in the Asian sector of Istanbul. He finally returned to Oxford in an emeritus capacity and remained there until his death.
The importance of sampling standardization for comparisons of insect herbivory in deep time: a case study from the late Palaeozoic
Authors: Schachat Sandra R. , Labandeira Conrad C. , Maccracken S. Augusta
Published: March 2018

Sampling standardization has not been fully addressed for the study of insect herbivory in the fossil record. The effects of sampling within a single locality were explored almost a decade ago, but the importance of sampling standardization for comparisons of herbivory across space and time has not yet been evaluated. Here, we present a case study from the Permian in which we evaluate the impact of sampling standardization on comparisons of insect herbivory from two localities that are similar in age and floral composition. Comparisons of insect damage type (DT) diversity change dramatically when the number of leaves examined is standardized by surface area. This finding suggests that surface area should always be taken into account for comparisons of DT diversity. In addition, the three most common metrics of herbivory—DT diversity, proportion of leaves herbivorized and proportion of leaf surface area herbivorized—are inherently decoupled from each other. The decoupling of the diversity and intensity of insect herbivory necessitates a reinterpretation of published data because they had been conflated in previous studies. Future studies should examine the divergent ecological factors that underlie these metrics. We conclude with suggestions to guide the sampling and analysis of herbivorized leaves in the fossil record.
Inference of Species Phylogenies from Bi-allelic Markers Using Pseudo-likelihood
Authors: Zhu Jiafan , Nakhleh Luay
Published: March 2018

Motivation

Phylogenetic networks represent reticulate evolutionary histories. Statistical methods for their inference under the multispecies coalescent have recently been developed. A particularly powerful approach uses data that consist of bi-allelic markers (e.g., single nucleotide polymorphism data) and allows for exact likelihood computations of phylogenetic networks while numerically integrating over all possible gene trees per marker. While the approach has good accuracy in terms of estimating the network and its parameters, likelihood computations remain a major computational bottleneck and limit the method’s applicability.

Results

In this paper, we first demonstrate why likelihood computations of networks take orders of magnitude more time when compared to trees. We then propose an approach for inference of phylo-genetic networks based on pseudo-likelihood using bi-allelic markers. We demonstrate the scalability and accuracy of phylogenetic network inference via pseudo-likelihood computations on simulated data. Furthermore, we demonstrate aspects of robustness of the method to violations in the underlying assumptions of the employed statistical model. Finally, we demonstrate the application of the method to biological data. The proposed method allows for analyzing larger data sets in terms of the numbers of taxa and reticulation events. While pseudo-likelihood had been proposed before for data consisting of gene trees, the work here uses sequence data directly, offering several advantages as we discuss.

Availability

The methods have been implemented in PhyloNet (http://bioinfocs.rice.edu/phylonet).

Contact

jiafan.zhu@rice.edu,nakhleh@rice.edu
Profiling copy number alterations in cell-free tumour DNA using a single-reference
Authors: Robertson Alan J , Xu Qinying , Song Sarah , Ganesamoorthy Devika , Benson Derek , Chen Wenhan , Ferguson Kaltin , Nones Katia , Lakhani Sunil R , Simpson Peter T , Waddell Nicola , Pearson John V , Coin Lachlan J.M.
Published: March 2018

Background

The accurate detection of copy number alterations from the analysis of circulating cell free tumour DNA (ctDNA) in blood is essential to realising the potential of liquid biopsies. However, currently available approaches require a large number of plasma samples from healthy individuals, sequenced using the same platform and protocols to act as a reference panel. Obtaining this reference panel can be challenging, prohibitively expensive and limits the ability to migrate to improved sequencing platforms and improved protocols.

Methods

We developed qCNV and sCNA-seq, two distinct tools that together provide a new approach for profiling somatic copy number alterations (sCNA) through the analysis of cell free DNA (cfDNA) without a reference panel. Our approach was designed to identify sCNA from cfDNA through the analysis of a single plasma sample and a matched normal DNA sample -both of which can be obtained from the same blood draw. qCNV is an efficient method for extracting read-depth from BAM files and sCNA-seq is a method that uses a probabilistic model of read depth to infer the copy number segmentation of the tumour. We compared the results from our pipeline to the established copy number profile of a cell-line, as well as the results from the plasma-Seq analysis of cfDNA-like mixtures and real, clinical data-sets.

Results

With a single, unmatched, germline reference sample, our pipeline recapitulated the known copy number profile of a cell-line and demonstrated similar results to those obtained from plasma-Seq. With less than 1X genome coverage, our approach identified clinically relevant sCNA in samples with as little as 20 % tumour DNA. When applied to plasma samples from cancer patients, our pipeline identified clinically significant mutations.

Conclusions

These results show it is possible to identify therapeutically-relevant copy number mutations from plasma samples without the need to generate a reference panel from a large number of healthy individuals. Together with the range of sequencing platforms supported by our qCNV+sCNA-Seq pipeline, as well as the Galaxy implementation of this solution, this pipeline makes cfDNA profiling more accessible and makes it easier to identify sCNA from the plasma of cancer patients.
Dissociable Roles for Working Memory in Sensorimotor Learning
Authors: McDougle Samuel D. , Taylor Jordan A.
Published: March 2018

The computations underlying cognitive strategies in sensorimotor learning are poorly understood. Here we investigate such strategies in a sensorimotor transformation task. We show that strategies assume two forms, reflecting distinct working memory representations: discrete response caching of stimulus-response contingencies (e.g., look-up table; RC), and time-consuming parametric computations (e.g. mental rotation; MR). Subjects’ reaction times and errors suggest that both strategies are employed during learning, and trade off based on the progress of learning and the complexity of the task. Experiments using pressured preparation time support these working memory mechanisms: In discrete RC, time pressure elicits bimodal distributions of movements, in agreement with cached responses; in parametric MR, time pressure elicits a shifting distribution producing intermediate movements between visual targets and distal goals, consistent with analog re-computing of a movement plan. These results provide a specific model of working memory contributions to motor learning.
Host Diet Influences Lethal and Sublethal Responses of Hosts to Amphibian Pathogen Exposure
Authors: Rumschlag Samantha L. , Boone Michelle D.
Published: March 2018

Abstract

The severity of the impacts of pathogens on hosts may be driven by environmental factors like resource availability that create tradeoffs on energetic demands for immune responses and basal metabolic activity within the host. These responses can vary among species from sublethal to lethal effects, which can have consequences for the host population trajectories within a community. Chytridiomycosis, caused by the pathogen Batrachochytrium dendrobatidis (or Bd), has been associated with global amphibian population declines. However, it also occurs in populations without appearing to cause mass mortality; the effect of Bd in these situations is not well understood and environmental factors like food abundance that impact host conditions could play an important role in the magnitude of the pathogen’s impact. In the present study, we exposed American toad (Anaxyrus americanus), northern leopard frog (Lithobates pipiens), and Blanchard’s cricket frog (Acris blanchardi) metamorphs to Bd and then reared them in the terrestrial habitat under low or high food environments. We found additive effects of Bd and reduced food abundance on host growth and survival that varied according to species. For instance, Bd-induced reductions in American toad survival were greater under low food conditions compared to high food conditions but survival of northern leopard frogs and Blanchard’s cricket frogs was not affected by Bd. For northern leopard frogs and Blanchard’s cricket frogs, low food abundance resulted in the lower growth rates under Bd exposure compared to high food abundance. Additionally, we developed stage-structured population models for American toads to assess if reduced survival of metamorphs exposed to Bd under conditions of low and high food abundance could influence population trajectories; models indicated that Bd exposure would reduce annual population growth rates by 14% under conditions of high food abundance and 21% under conditions of low food abundance. Our results suggest that environmental conditions that influence resource availability for species that are sensitive or tolerant to Bd may increase the negative effects of Bd on host growth and survival, which could have important implications for how populations and communities with infected members respond over time.
dtangle: accurate and fast cell-type deconvolution
Authors: Hunt Gregory J. , Freytag Saskia , Bahlo Melanie , Gagnon-Bartsch Johann A.
Published: March 2018

Motivation

Understanding cell type composition is important to understanding many biological processes. Furthermore, in gene expression studies cell type composition can confound differential expression analysis (DEA). To aid understanding cell type composition, methods of estimating (deconvolving) cell type proportions from gene expression data have been developed.

Results

We propose dtangle, a new cell-type deconvolution method. dtangle works on a range of DNA microarray and bulk RNA-seq platforms. It estimates cell-type proportions using publicly available, often cross-platform, reference data. To comprehensively evaluate dtangle, we assemble ten benchmark data sets. Here, dtangle is competitive with published deconvolution methods, is robust to selection of tuning parameters and is quicker than other methods. As a case study, we investigate the human immune response to Lyme disease. dtangle’s estimates reveal a temporal trend consistent with previous findings and are important covariates for DEA across disease status.

Availability

dtangle is on CRAN (cran.r-project.org/package=dtangle) or github (dtangle.github.io).

Contact

gjhunt@umich.edu
The functional brain organization of an individual predicts measures of social abilities in autism spectrum disorder: Predicting symptoms in autism with brain imaging
Authors: Lake Evelyn MR , Finn Emily S , Noble Stephanie M , Vanderwal Tamara , Shen Xilin , Rosenberg Monica D , Spann Marisa N , Chun Marvin M , Scheinost Dustin , Todd Constable R
Published: March 2018

Autism Spectrum Disorder (ASD) is associated with multiple complex abnormalities in functional brain connectivity measured with functional magnetic resonance imaging (fMRI). Despite much research in this area, to date, neuroimaging-based models are not able to characterize individuals with ASD with sufficient sensitivity and specificity; this is likely due to the heterogeneity and complexity of this disorder. Here we apply a data-driven subject-level approach, connectome-based predictive modeling, to resting-state fMRI data from a set of individuals from the Autism Brain Imaging Data Exchange. Using leave-one-subject-out and split-half analyses, we define two functional connectivity networks that predict continuous scores on the Social Responsiveness Scale (SRS) and Autism Diagnostic Observation Schedule (ADOS) and confirm that these networks generalize to novel subjects. Notably, these networks were found to share minimal anatomical overlap. Further, our results generalize to individuals for whom SRS/ADOS scores are unavailable, predicting worse scores for ASD than typically developing individuals. In addition, predicted SRS scores for individuals with attention-deficit/hyperactivity disorder (ADHD) from the ADHD-200 Consortium are linked to ADHD symptoms, supporting the hypothesis that the functional brain organization changes relevant to ASD severity share a component associated with attention. Finally, we explore the membership of predictive connections within conventional (atlas-based) functional networks. In summary, our results suggest that an individual’s functional connectivity profile contains information that supports dimensional, non-binary classification in ASD, aligning with the goals of precision medicine and individual-level diagnosis.
Quantification of Phase-Amplitude Coupling in Neuronal Oscillations: Comparison of Phase-Locking Value, Mean Vector Length, and Modulation Index
Authors: Hülsemann Mareike J. , Dr. rer. nat  , Naumann Ewald , Dr. rer. nat  , Rasch Björn
Published: March 2018

Phase-amplitude coupling is a promising construct to study cognitive processes in electroencephalography (EEG) and magnetencephalography (MEG). Due to the novelty of the concept, various measures are used in the literature to calculate phase-amplitude coupling. Here, performance of the three most widely used phase-amplitude coupling measures – phase-locking value (PLV), mean vector length (MVL), and modulation index (MI) – is thoroughly compared with the help of simulated data. We combine advantages of previous reviews and use a realistic data simulation, examine moderators and provide inferential statistics for the comparison of all three indices of phase-amplitude coupling. Our analyses show that all three indices successfully differentiate coupling strength and coupling width when monophasic coupling is present. While the mean vector length was most sensitive to modulations in coupling strengths and width, biphasic coupling can solely be detected by the modulation index. Coupling values of all three indices were influenced by moderators including data length, signal-to-noise-ratio, and sampling rate when approaching Nyquist frequencies. The modulation index was most robust against confounding influences of these moderators. Based on our analyses, we recommend the modulation index for noisy and short data epochs with unknown forms of coupling. For high quality and long data epochs with monophasic coupling and a high signal-to-noise ratio, the use of the mean vector length is recommended. Ideally, both indices are reported simultaneously for one data set.

Highlights

mean vector length is most sensitive for differentiating coupling strength

modulation index is most robust to differences in data length, sampling rate and SNR

phase-locking value and mean vector length cannot detect biphasic phase-amplitude coupling
Cell membranes resist flow
Authors: Shi Zheng , Graber Zachary T. , Baumgart Tobias , Stone Howard A. , Cohen Adam E.
Published: March 2018

The fluid-mosaic model posits a liquid-like plasma membrane, which can flow in response to tension gradients. It is widely assumed that membrane flow transmits local changes in membrane tension across the cell in milliseconds. This conjectured signaling mechanism has been invoked to explain how cells coordinate changes in shape, motility, and vesicle fusion, but the underlying propagation has never been observed. Here we show that propagation of membrane tension occurs quickly in cell-attached blebs, but is largely suppressed in intact cells. The failure of tension to propagate in cells is explained by a fluid dynamical model that incorporates the flow resistance from cytoskeleton-bound transmembrane proteins. In primary endothelial cells, local increases in membrane tension lead only to local activation of mechanosensitive ion channels and to local vesicle fusion. Thus membrane tension is not a mediator of long-range intra-cellular signaling, but local variations in tension mediate distinct processes in sub-cellular domains.
Fast calcium transients in neuronal spines driven by extreme statistics
Authors: Basnayake Kanishka , Korkotian Eduard , Holcman David
Published: March 2018

Extreme statistics describe the distribution of rare events that can define the timescales of transduction within cellular microdomains. We combine biophysical modeling and analysis of live-cell calcium imaging to explain the fast calcium transient in spines. We show that in the presence of a spine apparatus (SA), which is an extension of the smooth endoplasmic reticulum (ER), calcium transients during synaptic inputs rely on rare and extreme calcium ion trajectories. Using numerical simulations, we predicted the asymmetrical distributions of Ryanodine receptors and SERCA pumps that we confirmed experimentally. When calcium ions are released in the spine head, the fastest ions arriving at the base determine the transient timescale through a calcium-induced calcium release mechanism. In general, the fastest particles arriving at a small target are likely to be a generic mechanism that determines the timescale of molecular transduction in cellular neuroscience.

Significance statement

Intrigued by fast calcium transients of few milliseconds in dendritic spines, we investigated its underlying biophysical mechanism. We show here that it is generated by the diffusion of the fastest calcium ions when the spine contains a Spine Apparatus, an extension of the endoplasmic reticulum. This timescale is modulated by the initial number of released calcium ions and the asymmetric distribution of its associated calcium release associated Ryanodyne receptors, present only at the base of a spine. This novel mechanism of calcium signaling that we have unraveled here is driven by the fastest particles. To conclude, the rate of arrival of the fastest particles (ions) to a small target receptor defines the timescale of activation instead of the classical forward rate of chemical reactions introduced by von Smoluchowski in 1916. Applying this new rate theory to transduction should refine our understanding of the biophysical mechanisms underlying molecular signaling.
Towards a bioelectronic computer: A theoretical study of a multi-layer biomolecular computing system that can process electronic inputs
Authors: Dunn Katherine E. , Trefzer Martin A. , Johnson Steven , Tyrrell Andy M.
Published: March 2018

DNA molecular machines have great potential for use in computing systems. Since Adleman originally introduced the concept of DNA computing through his use of DNA strands to solve a Hamiltonian path problem, a range of DNA-based computing elements have been developed, including logic gates, neural networks, finite state machines (FSMs) and non-deterministic universal Turing machines. It has also been established that DNA molecular machines can be controlled using electrical signals and that the state of DNA nanodevices can be measured using an electrochemical readout. However, to the best of our knowledge there has as yet been no demonstration of a fully integrated biomolecular computing system that has multiple levels of information processing capacity, can accept electronic inputs and is capable of independent operation. In this paper we address the question of how such a system could work. We present simulation results showing that such an integrated hybrid system could convert electrical impulses into biomolecular signals, perform logical operations and take a decision, storing its history. We also illustrate theoretically how such a system could potentially be used to perform a task such as controlling an autonomous robot navigating through a maze.
Does deterministic coexistence theory matter in a finite world?
Authors: Schreiber Sebastian J. , Levine Jonathan M. , Godoy Oscar , Kraft Nathan J.B. , Hart Simon P.
Published: March 2018

Contemporary studies of species coexistence are underpinned by deterministic models that assume that competing species have continuous (i.e. non-integer) densities, live in infinitely large landscapes, and coexist over infinite time horizons. By contrast, in nature species are composed of discrete individuals subject to demographic stochasticity, and occur in habitats of finite size where extinctions occur in finite time. One consequence of these discrepancies is that metrics of species coexistence derived from deterministic theory may be unreliable predictors of the duration of species coexistence in nature. These coexistence metrics include invasion growth rates and niche and fitness differences, which are now commonly applied in theoretical and empirical studies of species coexistence. Here we test the efficacy of deterministic coexistence metrics on the duration of species coexistence in a finite world. We introduce new theoretical and computational methods to estimate coexistence times in stochastic counterparts of classic deterministic models of competition. Importantly, we parameterized this model using experimental field data for 90 pairwise combinations of 18 species of annual plants, allowing us to derive biologically-informed estimates of coexistence times for a natural system. Strikingly, we find that for species expected to deterministically coexist, habitat sizes containing only tens of individuals have predicted coexistence times of greater than 1, 000 years. We also find that invasion growth rates explain 60% of the variation in intrinsic coexistence times, reinforcing their general usefulness in studies of coexistence. However, only by integrating information on both invasion growth rates and species’ equilibrium population sizes could most (> 99%) of the variation in species coexistence times be explained. This integration is achieved with demographically uncoupled single species models solely determined by the invasion growth rates and equilibrium population sizes. Moreover, because of a complex relationship between niche overlap/fitness differences and equilibrium population sizes, increasing niche overlap and increasing fitness differences did not always result in decreasing coexistence times as deterministic theory would predict. Nevertheless, our results tend to support the informed use of deterministic theory for understanding the duration of species coexistence, while highlighting the need to incorporate information on species’ equilibrium population sizes in addition to invasion growth rates.
The Impact Of Thigh And Shank Marker Quantity On Lower Extremity Kinematics Using A Constrained Model
Authors: Slater Annelise A , Hullfish Todd J. , Baxter Josh R.
Published: March 2018

Musculoskeletal models are commonly used to quantify joint motions and loads during human motion. Constraining joint kinematics simplifies these models but the implications of the number of markers used during data acquisition remains unclear. The purpose of this study was to establish the effects of marker placement and quantity on kinematic fidelity when using a constrained-kinematic model. We hypothesized that a constrained-kinematic model would faithfully reproduce lower extremity kinematics regardless of the number of tracking markers removed from the thigh and shank. Healthy-young adults (N = 10) walked on a treadmill at slow, moderate, and fast speeds while skin-mounted markers were tracked using motion capture. Lower extremity kinematics were calculated for 256 combinations of leg and shank markers to establish the implications of marker placement and quantity on joint kinematics. Sagittal joint and hip coronal kinematics errors were smaller than documented errors caused by soft-tissue artifact, which tends to be approximately 5 degrees, when excluding thigh and shank markers. Joint angle and center kinematic errors negatively correlated with the number of markers included in the analyses (R2 > 0.97) and typically showed the greatest error reductions when two markers were included. Further, we demonstrated that a simplified marker set that included markers on the pelvis, lateral knee condyle, lateral malleolus, and shoes produced kinematics that strongly agreed with the traditional marker set. In conclusion, constrained-kinematic models are resilient to marker placement and quantity, which has implications on study design and post-processing workflows.

Ethics Approval and Consent to Participate this study was approved by the Institutional Review Board at the University of Pennsylvania (#824466). Subjects provided written-informed consent

Consent to Publish this submission does not contain any individual data

Availability of Data and Materials the datasets analyzed in this study are available from the corresponding author on reasonable request.

Competing Interests one author (JB) is an associate editor for BMC Musculoskeletal Disorders. None of the other authors have any competing interests.

Funding no funding has been provided for this research

Authors’ Contributions

AS, TH, and JB designed the experiment; AS and TH collected the data; AS and JB analyzed and interpreted the data; AS and JB drafted the manuscript; AS, TH, and JB revised the intellectual content of the manuscript; AS, TH, and JB approved the final version of the manuscript; and AS, TH, and JB agreed to be accountable for all aspects of the study.
A gate-and-switch model for head orientation behaviors in C. elegans
Authors: Ouellette Marie-Hélène , Desrochers Melanie J. , Gheta Ioana , Ramos Ryan , Hendricks Michael
Published: March 2018

The nervous system seamlessly integrates perception and action. This ability is essential for stable representation of and appropriate responses to the external environment. How the sensorimotor integration underlying this ability occurs at the level of individual neurons is of keen interest. In Caenorhabditis elegans, RIA interneurons receive input from sensory pathways and have reciprocal connections with head motor neurons. Through separate physiological mechanisms, RIA simultaneously encodes both head orientation and sensory stimuli. Based on these observations, we proposed a model for how RIA may integrate these two signals to detect the spatial distribution of stimuli across head sweeps and generate directional head responses. Here, we show that blocking synaptic release from RIA disrupts head orientation behaviors in response to unilaterally presented stimuli. We found that sensory encoding in RIA is gated according to head orientation. This dependence on head orientation is independent of motor encoding in RIA, suggesting a second, posture-dependent pathway upstream of RIA. This gating mechanism may allow RIA to selectively attend to stimuli that are asymmetric across head sweeps. Attractive odor removal during head bends triggers rapid head withdrawal in the opposite direction. Unlike sensory encoding, this directional response is dependent on motor inputs to and synaptic output from RIA. Together, these results suggest that RIA is part of a sensorimotor pathway that is dynamically regulated according to head orientation at two levels: the first is a gate that filters sensory representations in RIA, and the second is a switch that routes RIA synaptic output to dorsal or ventral head motor neurons.
A bone marrow niche-derived molecular switch between osteogenesis and hematopoiesis
Authors: Galán-Díez Marta , Kousteni Stavroula
Published: March 2018

Hematopoietic stem cells (HSCs) reside and are maintained in specialized microenvironments within the bone marrow known as niches, which are comprised of various cell types. Among them, leptin receptor (LepR)-expressing CXC chemokine ligand 12 (CXCL12)-abundant reticular (CAR) cells are known to create a niche for HSCs and at the same time to give rise to osteoblasts. These two functions of CAR/LepR+ cells appear to be tightly but inversely regulated to ensure adequate physical space for HSCs. However, how osteogenesis is prevented in CAR cells to maintain spaces available for HSCs and hematopoiesis remains unclear. In this issue of Genes & Development, Seike and colleagues (pp. 359–372) report that the transcription factor early B-cell factor (Ebf3) is preferentially expressed by CAR/LepR+ cells and inhibits CAR cell differentiation into osteoblasts while at the same time maintaining self-renewal of CAR/LepR+ cells. Using conditional knockout and retroviral systems, the investigators show that loss of Ebf3 in CAR cells impairs HSC numbers and leads to osteosclerosis. This study provides novel insights into transcriptional requirements for CAR cell bone formation by identifying Ebf3 as a niche factor secreted from CAR/Lepr+ cells that regulates the interplay between osteogenesis and hematopoiesis.
A finite-element approach to dynamical diffraction problems in reflection geometry
Authors: Honkanen Ari-Pekka , Ferrero Claudio , Guigay Jean-Pierre , Mocella Vito
Published: March 2018

A finite-element approach to the numerical solution of the Takagi–Taupin equations expressed in a weak form is presented and applied to simulate the X-ray reflectivity curves, spatial intensity distributions and focusing properties of bent perfect crystals in symmetric reflection geometry. The proposed framework encompasses a new formulation of the Takagi–Taupin equations, which appears to be promising in terms of robustness and stability and supports the Fresnel propagation of the diffracted waves. The presented method is very flexible and has the potential of dealing with dynamical X-ray or neutron diffraction problems related to crystals of arbitrary shape and deformation. The reference implementation based on the commercial COMSOL Multiphysics software package is available to the relevant user community.
The high-intensity option of the SANS diffractometer KWS-2 at JCNS – characterization and performance of the new multi-megahertz detection system
Authors: Houston Judith Elizabeth , Brandl Georg , Drochner Matthias , Kemmerling Günter , Engels Ralf , Papagiannopoulos Aristeidis , Sarter Mona , Stadler Andreas , Radulescu Aurel
Published: March 2018

A new detection system based on an array of 3He tubes and innovative fast detection electronics has been installed on the high-intensity small-angle neutron scattering (SANS) diffractometer KWS-2 operated by the Jülich Centre for Neutron Science (JCNS) at the Heinz Meier-Leibnitz Zentrum in Garching, Germany. The new detection system is composed of 18 eight-pack modules of 3He tubes that work independently of one another (each unit has its own processor and electronics). To improve the read-out characteristics and reduce the noise, the detection electronics are mounted in a closed case on the rear of the 3He tubes' frame. The tubes' efficiency is about 85% (for λ = 5 Å) and the resolution slightly better than 8 mm. The new detection system is characterized by a dead-time constant of 3.3 µs per tube and an overall count rate as high as 6 MHz at 10% dead-time loss. Compared with the old detector this is an improvement by a factor of 60. The much higher count rate will shorten the measurement times and thus increase the number of experiments possible in a given time period by the optimal use of the high flux of up to 2 × 108 n cm−2 s−1 at the sample position. Combined with the event-mode operation capability, this will enable new scientific opportunities in the field of structural investigations of small soft-matter and biological systems. The implementation of the detector in the high-intensity concept on KWS-2, its characterization and its performance based on test experiments are reported in this paper.
A generalized VECM/VAR-DCC/ADCC framework and its application in the Black-Litterman model
Authors: Deng Qi
Published: March 2018

Purpose

The existing literature on the Black-Litterman (BL) model does not offer adequate guidance on how to generate investors’ views in an objective manner. Therefore, the purpose of this paper is to establish a generalized multivariate Vector Error Correction Model (VECM)/Vector Auto-Regressive (VAR)-Dynamic Conditional Correlation (DCC)/Asymmetric DCC (ADCC) framework, and applies it to generate objective views to improve the practicality of the BL model.

Design/methodology/approach

This paper establishes a generalized VECM/VAR-DCC/ADCC framework that can be utilized to model multivariate financial time series in general, and produce objective views as inputs to the BL model in particular. To test the VECM/VAR-DCC/ADCC preconditioned BL model’s practical utility, it is applied to a six-asset China portfolio (including one risk-free asset).

Findings

With dynamically optimized view confidence parameters, the VECM/VAR-DCC/ADCC preconditioned BL model offers clear advantage over the standard mean-variance method, and provides an automated portfolio optimization alternative to the classic BL approach.

Originality/value

The VECM/VAR-DCC/ADCC framework and its application in the BL model proposed by this paper provide an alternative approach to the classic BL method. Since all the view parameters, including estimated mean return vectors, conditional covariance matrices and pick matrices, are generated in the VECM/VAR and DCC/ADCC preconditioning stage, the model improves the objectiveness of the inputs to the BL stage. In conclusion, the proposed model offers a practical choice for automated portfolio balancing and optimization in a China context.
Perceived organizational support and employee well-being
Authors: Wattoo Mashal Ahmed , Zhao Shuming , Xi Meng
Published: March 2018

Purpose

Considering work and family responsibility has become an important issue due to changes in the lives of people, understanding work and family responsibilities is essential for organizations in assisting employees to increase their well-being. Therefore, the purpose of this paper is to find the impact of perceived organizational support (POS) on work–family facilitation (WFF) and work–family conflict (WFC) and eventually on employee well-being.

Design/methodology/approach

A survey questionnaire is administered to 1,340 employees of Chinese enterprises. Structural equation modeling is used to test the model fit.

Findings

Results of this study indicate a significant positive relationship between POS and WFF and significant negative relation between POS and WFC. Results of this paper also indicate that WFF and WFC partially mediate the relationship between POS and employee well-being.

Originality/value

Over the past two decades, the extent of research on work–family literature has been increased. Most of the work–family research works have been conducted in the Western countries. Very little is known about whether these results are applicable to Eastern societies. This study is extended to focus on work–family literature by drawing a sample from different regions of China. The findings of this study may provide a good understanding of WFC and WFF for Chinese employees. This study stresses the importance of providing organizational support to increase the well-being of employees.
The strategic national infrastructure assessment of digital communications
Authors: Oughton Edward J. , Frias Zoraida , Dohler Mischa , Whalley Jason , Sicker Douglas , Hall Jim W. , Crowcroft Jon , Cleevely David D.
Published: March 2018

Purpose

Public policy requires effective identification of the current and emerging issues being faced in industry and beyond. This paper aims to identify a set of key issues currently facing digital communications and reviews their relevance for the strategic provision of infrastructure, particularly within the UK context.

Design/methodology/approach

The methodology focusses on taking a horizon-scanning approach to obtaining current information from a range of authoritative decision makers across industry, government and academia. After structuring the issues identified, these areas are explored by a multi-disciplinary research team covering engineering, economics and computer science.

Findings

Five key categories were identified including future demand; coverage and capacity; policy and regulation; economics and business models; and technology. The results are reported for both fixed and wireless networks. Shared issues affecting the wider digital ecosystem are also identified including Brexit, connecting remote areas and the degree to which the economics of infrastructure allows for building multiple overlapping infrastructures. The authors find that future demand uncertainty is one of the major issues affecting the digital communications sector driven by rigid willingness-to-pay, weak revenue and an increasing shift from fixed to wireless technologies. Policy must create the market conditions that encourage the entry of new competitors with innovative thinking and disruptive business models.

Research limitations/implications

A limitation of the analysis is that it is quite UK-focussed; hence, further research could broaden this analysis to assessing issues at a continental or global scale.

Originality/value

The value of this paper originates from the breadth of the expert elicitation exercise carried out to gather the initial set of issues, followed by the analysis of this data by a multi-disciplinary team of researchers. The results direct a future research agenda, as many issues are indicative of a lack of existing evidence to support effective decision-making.
Capital structure as a control mechanism of a CSR entrenchment strategy
Authors: Villarón-Peramato Oscar , García-Sánchez Isabel-María , Martínez-Ferrero Jennifer
Published: March 2018

Purpose

This paper aims to analyse the use of level of debt as an external control mechanism against an entrenchment strategy based on corporate social responsibility (CSR) practices.

Design/methodology/approach

The authors use a database of 1,916 international companies for the years 2002 to 2010.

Findings

The evidence obtained confirms in a context of asymmetric information, bounded rationality and divergent interests, the use of debt as a control mechanism of managers’ discretionary comportment. In other words, CSR practices can be used by managers as an entrenchment strategy and self-defence with the aim of decreasing the possibility of being identified by those shareholders and stakeholders whose interests have been damaged. In this context, the market demands higher debt levels to solve agency frictions, playing an active role in monitoring the management. Moreover, the demand of higher debt as a control mechanism that minimises the expropriation risk by managers through CSR is lower in contexts of greater investor protection.

Originality/value

The findings reveal that CSR engagement can be explained by the hypothesis of being a strategy of entrenchment and self-defence. Overall, this study differs from previous literature in this field by taking an alternative approach to CSR practices, in contrast to the conventional wisdom of the benefits of CSR practices. The authors contribute by empirically testing the theoretical model proposed by Cespa and Cestone (2007) who suggest the discretionary use of CSR from an agency perspective. They also give empirical relief showing the use of CSR as an entrenchment strategy. Moreover, they demonstrate that the capital market of debt decreases in a context with a greater degree of investor protection, likewise under CSR promoted as an entrenchment tool, the demand for debt as a disciplinary mechanism is less necessary to control managers. In addition, the study is enriched by the database analysis.