bluuebunny/crossref_metadata_2025 huggingface dataset:
Underwater spark discharge with long transmission line for cleaning horizontal wells
Authors: Lee Kern , Chung Kyoung-Jae , Hwang Y. S. , Kim C. Y.
Published: June 2017

A transmission line is discussed for application in an underwater spark-discharge technique in the cleaning of a horizontal well by incorporating a power-transmission model into the simulation. The pulsed-spark-discharge technique has been proposed for clogged-well rehabilitation, because it removes incrustations that are attached to well screens by using strong pressure waves that are generated by the rapid expansion of a spark channel. To apply the pulsed-spark-discharge technique to the cleaning of horizontal wells, the coaxial cable between the pulsed power supply and the spark gap as a load needs to be extended to a few hundred meters. Prior to field application, pulsed-spark-discharge experiments were conducted and the role of the transmission line was examined using an improved simulation model. In the model, a non-linear interaction of the spark channel and the capacitor bank is described by the pulse-forming action of the coaxial cable. Based on the accurate physical properties of the water plasma, such as the equation of state and electrical conductivity within the region of interest, the amount of energy contributed to the development of a shock wave was evaluated. The simulation shows that if the initial conditions of the spark channel are the same, no further reduction in strength of the pressure wave occurs, even if the cable length is increased above 50 m. Hence, the degraded peak pressure that was observed in the experiments using the longer cable is attributed to a change in the initial condition of the spark channel. The parametric study suggests that the low initial charging voltage, the high ambient water pressure, and the long cable length yield the low initial spark-channel density, which results in a reduced peak pressure. The simulation of line charging is presented to discuss the principle of disturbing the pre-breakdown process by an extended cable.
Nonlinear dust-acoustic solitary waves and shocks in dusty plasmas with a pair of trapped ions
Authors: Adhikary Nirab C. , Misra Amar P. , Deka Manoj K. , Dev Apul N.
Published: June 2017

The propagation characteristics of small-amplitude dust-acoustic (DA) solitary waves (SWs) and shocks are studied in an unmagnetized dusty plasma with a pair of trapped positive and negative ions. Using the standard reductive perturbation technique with two different scalings of stretched coordinates, the evolution equations for DA SWs and shocks are derived in the form of complex Korteweg-de Vries and Burgers' equations. The effects of the dust charge variation, the dust thermal pressure, and the ratios of the positive to negative ion number densities as well as the free to trapped ion temperatures on the profiles of SWs and shocks are analysed and discussed.
Investigation of electron mobility and saturation velocity limits in gallium nitride using uniaxial dielectric continuum model
Authors: Park K. , Stroscio M. A. , Bayram C.
Published: June 2017

Here we introduce a uniaxial dielectric continuum model with temperature-dependent phonon mode frequencies to study temperature- and orientation-dependent polar-optical-phonon limited electron mobility and saturation velocity in uniaxial semiconductors. The formalism for calculating electron scattering rates, momentum relaxation rates, and rate of energy change as a function of the electron kinetic energy and incident electron angle with respect to the c-axis are presented and evaluated numerically. Electron–longitudinal-optical-phonon interactions are shown to depend weakly on the electron incident angle, whereas the electron–transverse-optical-phonon interactions around the emission threshold energy are observed to depend strongest on the electron incident angle when varied from π/4 to π/2 (with respect to the c-axis). We provide electron mobility and saturation velocity limits in different GaN crystal orientations as a function of temperature and electron concentration. At room temperature and for an electron density of 5 × 1018 cm−3, electron mobility limit of ∼3200 cm2/V s and electron saturation velocity limit of 3.15 × 107 cm/s are calculated. Both GaN electron mobility and saturation velocity are observed to be governed by the longitudinal-optical-phonon interaction, and their directional anisotropy is shown to vary less than 5% as the electron incident angle with respect to the c-axis is varied from 0 to π/2. Overall, we develop a theoretical formalism for calculating anisotropic properties of uniaxial wurtzite semiconductors.
Morphology and microstructure evolution of Ti-50 at.% Al cathodes during cathodic arc deposition of Ti-Al-N coatings
Authors: Syed Bilal , Zhu Jianqiang , Polcik Peter , Kolozsvari Szilard , Håkansson Greger , Johnson Lars , Ahlgren Mats , Jöesaar Mats , Odén Magnus
Published: June 2017

Today's research on the cathodic arc deposition technique and coatings therefrom primarily focuses on the effects of, e.g., nitrogen partial pressure, growth temperature, and substrate bias. Detailed studies on the morphology and structure of the starting material—the cathode—during film growth and its influence on coating properties at different process conditions are rare. This work aims to study the evolution of the converted layer, its morphology, and microstructure, as a function of the cathode material grain size during deposition of Ti-Al-N coatings. The coatings were reactively grown in pure N2 discharges from powder metallurgically manufactured Ti-50 at.% Al cathodes with grain size distribution averages close to 1800, 100, 50, and 10 μm, respectively, and characterized with respect to microstructure, composition, and mechanical properties. The results indicate that for the cathode of 1800 μm grain size the disparity in the work function among parent phases plays a dominant role in the pronounced erosion of Al, which yields the coatings rich in macro-particles and of high Al content. We further observed that a reduction in the grain size of Ti-50 at.% Al cathodes to 10 μm provides favorable conditions for self-sustaining reactions between Ti and Al phases upon arcing to form γ phase. The combination of self-sustaining reaction and the arc process not only result in the formation of hole-like and sub-hole features on the converted layer but also generate coatings of high Al content and laden with macro-particles.
Design and implementation of an optimal laser pulse front tilting scheme for ultrafast electron diffraction in reflection geometry with high temporal resolution
Authors: Pennacchio Francesco , Vanacore Giovanni M. , Mancini Giulia F. , Oppermann Malte , Jayaraman Rajeswari , Musumeci Pietro , Baum Peter , Carbone Fabrizio
Published: June 2017

Ultrafast electron diffraction is a powerful technique to investigate out-of-equilibrium atomic dynamics in solids with high temporal resolution. When diffraction is performed in reflection geometry, the main limitation is the mismatch in group velocity between the overlapping pump light and the electron probe pulses, which affects the overall temporal resolution of the experiment. A solution already available in the literature involved pulse front tilt of the pump beam at the sample, providing a sub-picosecond time resolution. However, in the reported optical scheme, the tilted pulse is characterized by a temporal chirp of about 1 ps at 1 mm away from the centre of the beam, which limits the investigation of surface dynamics in large crystals. In this paper, we propose an optimal tilting scheme designed for a radio-frequency-compressed ultrafast electron diffraction setup working in reflection geometry with 30 keV electron pulses containing up to 105 electrons/pulse. To characterize our scheme, we performed optical cross-correlation measurements, obtaining an average temporal width of the tilted pulse lower than 250 fs. The calibration of the electron-laser temporal overlap was obtained by monitoring the spatial profile of the electron beam when interacting with the plasma optically induced at the apex of a copper needle (plasma lensing effect). Finally, we report the first time-resolved results obtained on graphite, where the electron-phonon coupling dynamics is observed, showing an overall temporal resolution in the sub-500 fs regime. The successful implementation of this configuration opens the way to directly probe structural dynamics of low-dimensional systems in the sub-picosecond regime, with pulsed electrons.
The impact of alloy cluster scattering on low-temperature mobility of 2D electron gas in Zn1-xMgxO/ZnO heterostructures
Authors: Chen Hongyan , Wang Ping , Cheng Jingsi , Li Zhaoling , Guo Lixin
Published: June 2017

The influence of alloy cluster scattering on the electron transport properties in undoped Zn1-xMgxO/ZnO heterostructures was studied theoretically. Alloy cluster scattering is treated as an elastic scattering occurring between MgZnO clusters and electrons. The electron energies and wave functions are obtained to calculate the scattering rates of two-dimensional electron gas (2DEG) by solving the Schrödinger and Poisson equations self-consistently. The total low-temperature mobility is then calculated by using Matthiessen’s rule. It is found that the composition fluctuation of the Zn1-xMgxO barrier affects the mobility of electrons confined in the ZnO well via alloy cluster scattering. The electron mobility limited by alloy cluster scattering decreases with Mg composition fluctuation increased from 0.01 to 0.05. Furthermore, alloy cluster scattering is one of the dominant scattering mechanisms at low temperature. When alloy cluster scattering is taken into consideration, the simulated results are in better agreement with the experimental values for lower mobility samples with higher Mg composition. This work is useful for designing Zn1-xMgxO/ZnO heterostructure devices.
Hong Kong’s language ecology and the racialized linguistic order
Authors: Fleming Kara
Published: June 2017

This paper will argue that the role and status of the languages promoted as part of Hong Kong’s “trilingualism and biliteracy” policy cannot be understood without reference to each other and to their wider social, political and linguistic context. Particularly, in Hong Kong, race is a key mediating factor that structures social orders in which language is used and evaluated, and therefore its role in the ecology must be emphasized. This article will outline the links between language and social hierarchies of race, focusing particularly on the positioning of Hong Kong South Asians, based on ethnographic research in a Hong Kong secondary school and analysis of media and policy data. This approach is key to understanding the apparent contradictions in the evaluation of various languages spoken in Hong Kong, and demonstrates the necessity of a holistic, contextualized analysis of language and race.
Vicissitudes of laughter
Authors: McKenzie Kevin
Published: June 2017

This paper is concerned with the way that laughter is employed to manage threats to interlocutor affiliation in talk among humanitarian aid workers as they describe their professional activities in settings of armed conflict. I first set out to situate my analysis within the tradition of work in ethnomethodology and conversation analysis (EM), exploring how that approach differs in significant ways from work in pragmatics and related traditions of discourse analytic research. Unlike the latter approaches, EM examines laughter for the intelligibility it is deployed by speakers to furnish, so that the presumption of laughter’s revelatory nature which characterizes a pragmatically-oriented analysis is seen as a participant resource for rendering the situated significance of actions visible by and for the involved parties of a given episode of interaction. Following this, I examine talk from open-ended interviews with aid agency operatives who work in Israel and the Palestinian Territories, exploring how laughter is employed to manage threats to interlocutor affiliation where the potential accusation of opportunism arises in accounts of personal job satisfaction as against the legitimacy otherwise afforded with an appeal to altruism and self-sacrifice. Where speakers attend to the criticism of humanitarian activity for its significance in affecting outcomes of warfare, the management of these different demands is accomplished in reflexive work to ironize their own and others’ formulations of motivation for pursuing humanitarian work.
Influence of hydrostatic extrusion process on the microstructure and texture of polycrystalline nickel
Authors: Majda Tomasz , Moszczyńska Dorota , Zdunek Joanna , Kulczyk Mariusz , Mizera Jaroslaw , Kurzydłowski Krzysztof Jan
Published: June 2017

The evolution of the microstructure and texture of polycrystalline nickel, from its initial state to that after a hydrostatic extrusion process to total true strains of 0.5, 1.18, 1.62 and 2.2, were examined. Investigation of the microstructure revealed that the grain size was reduced from ∼32 µm to ∼200 nm. The local texture transformation and major boundary misorientation angles were discussed based on electron backscattered diffraction results, while XRD was used to give a qualitative and quantitative description of the global texture. Microhardness measurements were performed to investigate the changes in the mechanical properties of the deformed material.
Adenomatous polyposis coli nucleates actin assembly to drive cell migration and microtubule-induced focal adhesion turnover
Authors: Juanes M. Angeles , Bouguenina Habib , Eskin Julian A. , Jaiswal Richa , Badache Ali , Goode Bruce L.
Published: June 2017

Cell motility depends on tight coordination between the microtubule (MT) and actin cytoskeletons, but the mechanisms underlying this MT–actin cross talk have remained poorly understood. Here, we show that the tumor suppressor protein adenomatous polyposis coli (APC), which is a known MT-associated protein, directly nucleates actin assembly to promote directed cell migration. By changing only two residues in APC, we generated a separation-of-function mutant, APC (m4), that abolishes actin nucleation activity without affecting MT interactions. Expression of full-length APC carrying the m4 mutation (APC (m4)) rescued cellular defects in MT organization, MT dynamics, and mitochondrial distribution caused by depletion of endogenous APC but failed to restore cell migration. Wild-type APC and APC (m4) localized to focal adhesions (FAs), and APC (m4) was defective in promoting actin assembly at FAs to facilitate MT-induced FA turnover. These results provide the first direct evidence for APC-mediated actin assembly in vivo and establish a role for APC in coordinating MTs and actin at FAs to direct cell migration.
Keratinocytes produce IL-17c to protect peripheral nervous systems during human HSV-2 reactivation
Authors: Peng Tao , Chanthaphavong R. Savanh , Sun Sijie , Trigilio James A. , Phasouk Khamsone , Jin Lei , Layton Erik D. , Li Alvason Z. , Correnti Colin E. , De van der Schueren Willem , Vazquez Julio , O’Day Diana R. , Glass Ian A. , Knipe David M. , Wald Anna , Corey Lawrence , Zhu Jia
Published: June 2017

Despite frequent herpes simplex virus (HSV) reactivation, peripheral nerve destruction and sensory anesthesia are rare. We discovered that skin biopsies obtained during asymptomatic human HSV-2 reactivation exhibit a higher density of nerve fibers relative to biopsies during virological and clinical quiescence. We evaluated the effects of HSV infection on keratinocytes, the initial target of HSV replication, to better understand this observation. Keratinocytes produced IL-17c during HSV-2 reactivation, and IL-17RE, an IL-17c–specific receptor, was expressed on nerve fibers in human skin and sensory neurons in dorsal root ganglia. In ex vivo experiments, exogenous human IL-17c provided directional guidance and promoted neurite growth and branching in microfluidic devices. Exogenous murine IL-17c pretreatment reduced apoptosis in HSV-2–infected primary neurons. These results suggest that IL-17c is a neurotrophic cytokine that protects peripheral nerve systems during HSV reactivation. This mechanism could explain the lack of nerve damage from recurrent HSV infection and may provide insight to understanding and treating sensory peripheral neuropathies.
Critical role for Sec22b-dependent antigen cross-presentation in antitumor immunity
Authors: Alloatti Andrés , Rookhuizen Derek C. , Joannas Leonel , Carpier Jean-Marie , Iborra Salvador , Magalhaes Joao G. , Yatim Nader , Kozik Patrycja , Sancho David , Albert Matthew L. , Amigorena Sebastian
Published: June 2017

CD8+ T cells mediate antigen-specific immune responses that can induce rejection of solid tumors. In this process, dendritic cells (DCs) are thought to take up tumor antigens, which are processed into peptides and loaded onto MHC-I molecules, a process called “cross-presentation.” Neither the actual contribution of cross-presentation to antitumor immune responses nor the intracellular pathways involved in vivo are clearly established because of the lack of experimental tools to manipulate this process. To develop such tools, we generated mice bearing a conditional DC-specific mutation in the sec22b gene, a critical regulator of endoplasmic reticulum–phagosome traffic required for cross-presentation. DCs from these mice show impaired cross-presentation ex vivo and defective cross-priming of CD8+ T cell responses in vivo. These mice are also defective for antitumor immune responses and are resistant to treatment with anti–PD-1. We conclude that Sec22b-dependent cross-presentation in DCs is required to initiate CD8+ T cell responses to dead cells and to induce effective antitumor immune responses during anti–PD-1 treatment in mice.
The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite
Authors: Nasir Fahad , Bolton James S. , Viel Matteo , Kim Tae-Sun , Haehnelt Martin G. , Puchwein Ewald , Sijacki Debora
Published: June 2017

We study the effect of different feedback prescriptions on the properties of the low-redshift (z ≤ 1.6) Lyα forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback, active galactic nuclei (AGN) feedback and a simplified scheme for efficiently modelling the low column density Lyα forest. We confirm a discrepancy remains between Cosmic Origins Spectrograph (COS) observations of the Lyα forest column density distribution function (CDDF) at z ≃ 0.1 for high column density systems ($N_{\rm H\,\rm {\small I}}>10^{14}\rm \,cm^{-2}$), as well as Lyα velocity widths that are too narrow compared to the COS data. Stellar or AGN feedback – as currently implemented in our simulations – has only a small effect on the CDDF and velocity width distribution. We conclude that resolving the discrepancy between the COS data and simulations requires an increase in the temperature of overdense gas with Δ = 4–40, either through additional He$\,\rm \scriptstyle II\,$photoheating at z > 2 or fine-tuned feedback that ejects overdense gas into the intergalactic medium at just the right temperature for it to still contribute significantly to the Lyα forest. Alternatively a larger, currently unresolved turbulent component to the line width could resolve the discrepancy.
Does information entropy play a role in the expansion and acceleration of the Universe?
Authors: Pandey Biswajit
Published: June 2017

We propose an interpretation of the expansion and acceleration of the Universe from an information theoretic perspective. We obtain the time evolution of the configuration entropy of the mass distribution in a static universe and show that the process of gravitational instability leads to a rapid dissipation of configuration entropy during the growth of the density fluctuations making such a Universe entropically unfavourable. We find that in an expanding universe, the configuration entropy rate is governed by the expansion rate of the Universe and the growth rate of density fluctuations. The configuration entropy rate becomes smaller but still remains negative in a matter-dominated universe and eventually becomes zero at some future time in a Λ-dominated universe. The configuration entropy may have a connection to the dark energy and possibly plays a driving role in the current accelerating expansion of the Universe leading the Universe to its maximum entropy configuration.
Lipoabdominoplasty with Progressive Traction Sutures
Authors: Vera Cucchiaro Javier , Lostia Horacio , Velazquez Patricia , Liska Elizabeth
Published: June 2017

Background:

Proactively preserving Scarpa’s fascia and thus its intrinsic lymphatic drainage and tensile strength for suture placement can eliminate the need for drains after lipoabdominoplasty and therefore reduce the rate of seroma development. In this article, we describe the effectiveness of a modified progressive traction suture (PTS) technique, which enables us to lessen the most common complications and avoid hospital readmission; these sutures take 3–5 minutes of additional surgery time.

Methods:

Two hundred seventy-six patients (mean age, 38 years; range, 19–67 years), with a mean body mass index of 25 were included in this study. All patients underwent complete lipoabdominoplasty with ultrasound-assisted liposuction (VASER) throughout the abdomen and flanks. Abdominal rectus plication was performed in 100% of cases. All patients were operated on under spinal anesthesia and stayed overnight in hospital.

Results:

Of the 276 patients, 1.8% developed postoperative seromas. No patients developed hematomas. New wound closure was needed in 1.4% of patients, performed within 7–10 days of surgery, scar revision in 4.7%, residual liposuction under local anesthesia in 9.7%, and liposuction under sedation in 1%; deep vein thrombosis without thromboembolic phenomenon developed in 1%, none resulting in death. In addition, the use of a PTS technique is a time-saving procedure because it takes the surgeons between 3–5 minutes of operative time, unlike that of adhesion and/or separate traction, which takes between 30 and 45 minutes.

Conclusions:

The use of PTSs helped diminish complications such as seroma and hematoma and prevent additional cost involving hospital readmission and/or further surgery. Furthermore, use of these sutures required only 3–5 minutes of additional operative time.
Building DNP Essential Skills in Clinical Data Management and Analysis
Authors: Polancich Shea , James David H. , Miltner Rebecca S. , Smith Glenda L. , Moneyham Linda
Published: June 2017

Effectively teaching clinical data management and analysis in a doctor of nursing (DNP) program requires attention to developing skills that foster improvement at the bedside. The purpose of this article is to describe a DNP clinical data management and analysis course specific to translation and improvement in practice. The student evaluation scores are high; however, faculty evaluation identifies opportunities to improve translation and application at the point of the scholarly practice project.
Students and Faculty Perceptions of an Undergraduate Nursing Research Internship Program
Authors: O’Brien Tara , Hathaway Donna
Published: June 2017

Nursing students in baccalaureate programs report that research is not visible in practice, and faculty conducting research report rarely interacting with students in undergraduate nursing programs. We examined student and faculty perceptions of a research internship embedded in an existing evidence-based practice course. Students (n = 15) and faculty (n = 5) viewed the internship as a positive experience that provided meaningful hands-on skills while generating interest in a potential research career. The internship also provided faculty the opportunity to identify potential doctoral students.
Using Prospective Risk Analysis Tools to Improve Safety in Pharmacy Settings: A Systematic Review and Critical Appraisal
Authors: Stojkovic Tatjana , Marinkovic Valentina , Manser Tanja
Published: June 2017

Objectives

This study aimed to review and critically appraise the published literature on 2 selected prospective risk analysis tools, Failure Mode and Effects Analysis and Socio-Technical Probabilistic Risk Assessment, as applied to the dispensing of medicines in both inpatient and outpatient pharmacy settings.

Methods

A comprehensive search of electronic databases (PubMed and Scopus) was conducted (January 1990–March 2016), supplemented by hand search of reference lists. Eligible articles were assessed for data sources used for the risk analysis, uniformity of the risk quantification framework, and whether the analysis teams assembled were multidisciplinary.

Results

Of 1011 records identified, 11 articles met our inclusion criteria. These studies were mainly focused on dispensing of high-alert medications, and most were conducted in inpatient settings. The main risks identified were transcription, preparation, and selection errors, whereas the most common corrective actions included electronic transmission of prescriptions to the pharmacy, use of barcode, and medication safety training. Significant risk reduction was demonstrated by implementing corrective measures in both inpatient and outpatient pharmacy settings. The main Failure Mode and Effects Analysis limitations were its subjectivity and the lack of common risk quantification criteria.

Conclusions

The prospective risk analysis methods included in this review revealed relevant safety issues and hold significant potential for risk reduction. They were deemed suitable for application in both inpatient and outpatient pharmacy settings and should form an integral part of any patient safety improvement strategy.
Drug-Related Problems Identified at Patients’ Home: A Prospective Observational Study in a Rural Area of Thailand
Authors: Kongkaew Chuenjid , Methaneethorn Janthima , Mongkhon Pajaree , Dechanont Supinya , Taburee Watcharaporn
Published: June 2017

Objective

The aim of the study was to examine the prevalence rates, nature, and predictors of drug-related problems (DRPs) experienced in participants living at home in a rural Thailand.

Method

A cross-sectional observational study was undertaken during December 2015 to January 2016. Drug-related problems were identified within a rural township having a population of 5256 by means of home visits by pharmacists. All suspected cases were then assessed for severity and preventability by clinical specialists. Drug-related problems were categorized according to Pharmaceutical Care Network Europe classification (revised 2010).v.6.2

Results

From a systematically recruited cohort of 359 participants, suspected DRPs were identified in 160 participants. After detailed reviews by clinical specialists, 141 cases (39.3%) were deemed to have DRPs. Types of DRPs with prevalence rates were the following: problems of treatment effectiveness (3.7% of DPRs), adverse reactions (15.3%), treatment cost (28.4%), nonadherence to drugs (42.1%), and poor drug storage (10.5%). The most common drug to involve DRPs was those treating cardiovascular disease, especially simvastatin.

Conclusions

Nearly half of community living participants experienced DRPs, especially nonadherence to drugs, and has implications for other rural elderly persons of low education attainment for similar rural economies around the globe. Appropriate interventions should focus on reducing polypharmacy, providing outreach programs, and rigorous pharmacovigilance.
The rapid evolution of molecular genetic diagnostics in neuromuscular diseases
Authors: Volk Alexander E. , Kubisch Christian
Published: June 2017

Purpose of review

The development of massively parallel sequencing (MPS) has revolutionized molecular genetic diagnostics in monogenic disorders. The present review gives a brief overview of different MPS-based approaches used in clinical diagnostics of neuromuscular disorders (NMDs) and highlights their advantages and limitations.

Recent findings

MPS-based approaches like gene panel sequencing, (whole) exome sequencing, (whole) genome sequencing, and RNA sequencing have been used to identify the genetic cause in NMDs. Although gene panel sequencing has evolved as a standard test for heterogeneous diseases, it is still debated, mainly because of financial issues and unsolved problems of variant interpretation, whether genome sequencing (and to a lesser extent also exome sequencing) of single patients can already be regarded as routine diagnostics. However, it has been shown that the inclusion of parents and additional family members often leads to a substantial increase in the diagnostic yield in exome-wide/genome-wide MPS approaches. In addition, MPS-based RNA sequencing just enters the research and diagnostic scene.

Next-generation sequencing increasingly enables the detection of the genetic cause in highly heterogeneous diseases like NMDs in an efficient and affordable way. Gene panel sequencing and family-based exome sequencing have been proven as potent and cost-efficient diagnostic tools. Although clinical validation and interpretation of genome sequencing is still challenging, diagnostic RNA sequencing represents a promising tool to bypass some hurdles of diagnostics using genomic DNA.
Blind sparse deconvolution for inferring spike trains from fluorescence recordings
Authors: Tubiana Jérôme , Wolf Sébastien , Debregeas Georges
Published: June 2017

The parallel developments of genetically-encoded calcium indicators and fast fluorescence imaging techniques makes it possible to simultaneously record neural activity of extended neuronal populationsin vivo, opening a new arena for systems neuroscience. To fully harness the potential of functional imaging, one needs to infer the sequence of action potentials from fluorescence time traces. Here we build on recently proposed computational approaches to develop a blind sparse deconvolution algorithm (BSD), which we motivate by a theoretical analysis. We demonstrate that this method outperforms existing sparse deconvolution algorithms in terms of robustness, speed and/or accuracy on both synthetic and real fluorescence data. Furthermore, we provide solutions for the practical problems of thresholding and determination of the rise and decay time constants. We provide theoretical bounds on the performance of the algorithm in terms of precision-recall and temporal accuracy. Finally, we extend the computational framework to support temporal superresolution whose performance is established on real data.
Quantifying the Risk and Cost of Active Monitoring for Infectious Diseases
Authors: Reich Nicholas G , Lessler Justin , Varma Jay K , Vora Neil M
Published: June 2017

During outbreaks of deadly emerging pathogens (e.g., Ebola, MERS-CoV) and bioterror threats (e.g., smallpox), actively monitoring potentially infected individuals aims to limit disease transmission and morbidity. Guidance issued by CDC on active monitoring was a cornerstone of its response to the West Africa Ebola outbreak. There are limited data on how to balance the costs and performance of this important public health activity. We present a framework that estimates the risks and costs of specific durations of active monitoring for pathogens of significant public health concern. We analyze data from New York City’s Ebola active monitoring program over a 16-month period in 2014-2016. For monitored individuals, we identified unique durations of active monitoring that minimize expected costs for those at “low (but not zero) risk” and “some or high risk”: 21 and 31 days, respectively. Extending our analysis to smallpox and MERS-CoV, we found that the optimal length of active monitoring relative to the median incubation period was reduced compared to Ebola due to less variable incubation periods. Active monitoring can save lives but is expensive. Resources can be most effectively allocated by using exposure-risk categories to modify the duration or intensity of active monitoring.
The Mouse Cortical Interareal Network Reveals Well Defined Connectivity Profiles and an Ultra Dense Cortical Graph
Authors: Gămănuţ Răzvan , Kennedy Henry , Toroczkai Zoltán , Van Essen David , Knoblauch Kenneth , Burkhalter Andreas
Published: June 2017

The inter-areal wiring pattern of mouse cerebral cortex was analyzed in relation to an accurate parcellation of cortical areas. Twenty-seven retrograde tracer injections were made in 19 areas of a 41 area (plus 7 sub-area) parcellation of the mouse neo-, parahippocampal and perirhinal cortex. Flat mounts of the cortex and multiple histological markers enabled detailed counts of labeled neurons in individual areas. A weight index was determined for each area-to-area pathway based on the Fraction of Extrinsically Labeled Neurons (FLNe). Data analysis allowed cross species comparison with the macaque. Estimation of FLNe statistical variability based on repeat injections revealed high consistency across individuals and justifies using a single injection per area to characterize connectivity. The observed lognormal distribution of connections to each cortical area spanned 5 orders of magnitude and revealed a distinct connectivity profile for each area, analogous to that observed in macaque. The resulting graph has a density of 97% (i.e. 97% of connections that can exist do exist), considerably higher than the 66% density reported for the macaque. Our results provide more sharply defined connectivity profiles and a markedly higher graph density than shown in a recent probabilistic mouse connectome.
Superior Colliculus Neuronal Ensemble Activity Signals Optimal Rather Than Subjective Confidence
Authors: Odegaard Brian , Grimaldi Piercesare , Cho Seong Hah , Peters Megan A.K. , Lau Hakwan , Basso Michele A.
Published: June 2017

Recent studies suggest that neurons in sensorimotor circuits involved in perceptual decision-making also play a role in decision confidence. In these studies, confidence is often considered to be an optimal readout of the probability that a decision is correct. However, the information leading to decision accuracy and the report of confidence often co-varied, leaving open the possibility that there are actually two dissociable signal types in the brain: signals that correlate with decision accuracy (optimal confidence) and signals that correlate with subjects’ behavioral reports of confidence (subjective confidence). We recorded neuronal activity from a sensorimotor decision area, the superior colliculus (SC) of monkeys, while they performed two different tasks. In our first task, decision accuracy and confidence co-varied, as in previous studies. In our second task, we implemented a novel motion discrimination task with stimuli that were matched for decision accuracy but produced different levels of confidence as reflected by behavioral reports. We used a multivariate decoder to predict monkeys’ choices from neuronal population activity. As in previous studies on perceptual decision-making mechanisms, we found that neuronal decoding performance increased as decision accuracy increased. However, when decision accuracy was matched, performance of the decoder was similar between high and low subjective confidence conditions. These results show that the SC likely signals optimal decision confidence similar to previously reported cortical mechanisms, but is unlikely to play a critical role in subjective confidence. The results also motivate future investigations to determine where in the brain signals related to subjective confidence reside.

Significance Statement

Confidence is thought to reflect the rational or optimal belief concerning one’s choice accuracy. Here, we introduce a novel version of the dot-motion discrimination task with stimulus conditions that produce similar accuracy but different subjective behavioral reports of confidence. We decoded decision performance of this task from neuronal signals in the superior colliculus (SC), a subcortical region involved in decision-making. We found that SC activity signaled a perceptual decision for visual stimuli, with the strength of this activity reflecting decision accuracy, but not the subjective level of confidence as reflected by behavioral reports. These results demonstrate an important role for the SC in perceptual decision-making and challenge current ideas about how to measure subjective confidence in monkeys and humans.
Transit and integration of extracellular mitochondria in human heart cells
Authors: Cowan Douglas B. , Yao Rouan , Thedsanamoorthy Jerusha K. , Zurakowski David , del Nido Pedro J. , McCully James D.
Published: June 2017

Tissue ischemia adversely affects the function of mitochondria, which results in impairment of oxidative phosphorylation and compromised recovery of the affected organ. The impact of ischemia on mitochondrial function has been most extensively studied in the heart because of the morbidity and mortality associated with injury to this organ. Because conventional methods to preserve cell viability and function following an ischemic injury are limited in their efficacy, we developed a unique approach to protect the heart by transplanting respiration-competent mitochondria isolated from a non-ischemic tissue to the ischemic region. Our experiments in animals have shown that transplantation of isolated mitochondria to injured heart tissue leads to decreases in cell death, increases in energy production, and improvements in contractile function. We also discovered that exogenously-derived mitochondria injected or perfused into ischemic hearts were readily internalized by cardiac cells through actin-dependent endocytosis. Here, we describe the use of three-dimensional super-resolution microscopy and transmission electron microscopy to determine the intracellular fate of exogenous mitochondria in non-dividing human iPS-derived cardiomyocytes and dividing primary human cardiac fibroblasts. We show isolated mitochondria are internalised in human cardiac cells within minutes and then transported to endosomes and lysosomes. The majority of exogenous mitochondria escape from these compartments and fuse with the endogenous mitochondrial network, while some organelles are degraded through hydrolysis. Understanding this process may guide the development of treatments directed at replacing or augmenting impaired mitochondria in ischemic tissues and provide new options to rejuvenate dysfunctional mitochondria in a wide range of human diseases and disorders.
Hypoosmolar dose-dependent swelling occurs in both pyramidal neurons and astrocytes in acute hippocampal slices
Authors: Murphy Thomas R. , Davila David , Cuvelier Nicholas , Young Leslie R. , Lauderdale Kelli , Binder Devin K. , Fiacco Todd A.
Published: June 2017

Normal nervous system function is critically dependent on the balance of water and ions in the extracellular space. Pathological reduction in brain interstitial osmolarity results in osmotically-driven flux of water into cells, causing cellular edema which reduces the extracellular space and increases neuronal excitability and risk of seizures. Astrocytes are widely considered to be particularly susceptible to cellular edema due to selective expression of the water channel aquaporin-4 (AQP4). The apparent resistance of pyramidal neurons to osmotic swelling has been attributed to lack of functional water channels. In this study we report rapid volume changes in CA1 pyramidal cells in hypoosmolar ACSF (hACSF) that are equivalent to volume changes in astrocytes across a variety of conditions. Astrocyte and neuronal swelling was significant within 1 minute of exposure to 17 or 40% hACSF, was rapidly reversible upon return to normosmolar ACSF, and repeatable upon re-exposure to hACSF. Neuronal swelling was not an artifact of patch clamp, occurred deep in tissue, was similar at physiological vs. room temperature, and occurred in both juvenile and adult hippocampal slices. Neuronal swelling was neither inhibited by TTX, nor by antagonists of NMDA or AMPA receptors, suggesting that it was not occurring as a result of excitotoxicity. Surprisingly, genetic deletion of AQP4 did not inhibit, but rather augmented, astrocyte swelling in severe hypoosmolar conditions. Taken together, our results indicate that neurons are not osmoresistant as previously reported, and that osmotic swelling is driven by an AQP4-independent mechanism.
Specific Patterns of Bold Variability Associated with the Processing of Pain Stimuli
Authors: Costa Tommaso , Nani Andrea , Manuello Jordi , Vercelli Ugo , Tatu Mona-Karina , Cauda Franco
Published: June 2017

It is well known that the blood oxygen level dependent (BOLD) signal varies according to task performance and region specificity. This ongoing and fluctuating activity reflects the organization of functional brain networks. Peculiar dynamics of BOLD signal are therefore supposed to characterize brain activity in different conditions. Within this framework, we investigated through a multivoxel pattern analysis whether patterns of BOLD variability convey information that may allow an efficient discrimination between task (i.e., painful stimulation) and rest conditions. We therefore identified the most discriminative brain areas between the two conditions, which turned out to be the anterior insula, dorsal anterior cingulate cortex, posterior insula, the thalamus, and the periaqueductal gray. Then, on the basis of information theory, we calculated the entropy of their different time series. Entropy was found to distribute differently between these brain areas. The posterior insula was found to be is the smaller contributor to the entropy rate, whereas the system formed by the thalamus and periaqueductal gray was found to be the major contributor. Overall, the brain system reaches a higher level of entropy during the rest condition, which suggests that cerebral activity is characterized by a larger informational space when the brain is at rest than when it is engaged in a specific task. Thus, this study provides evidence that: i) the pattern of BOLD variance allow a good discrimination between the conditions of rest and pain stimulation; ii) the discriminative pattern resembles closely that of the functional network that has been calledpain matrix; iii) brain areas with high and low variability are characterized by a different sample entropy; iv) the entropy rate of cerebral regions can be an insightful parameter to better understand the complex dynamics of the brain.
Barriers of entrepreneurial intention among Qatari male students
Authors: Kebaili Boumediene , Al-Subyae Saif Saeed , Al-Qahtani Fahed
Published: June 2017

Purpose

The purpose of this paper is to examine the effects of psychological and institutional factors on the entrepreneurial intention among Qatari male students. Qatar has the world highest incomes per capita. Recently, the government launched many initiatives to stimulate Qatari’s to engage in entrepreneurship activities.

Design/methodology/approach

Data were collected by means of a questionnaire. The target population of this research were Qatari male students in the final year of Bachelor degree in Management. A total of 155 responses were used for the purpose of this study.

Findings

The findings indicate that Qatari male students hold a high entrepreneurial intention. In addition, two institutional barriers and three psychological barriers were found to be associated with the entrepreneurial intention.

Research limitations/implications

It would be interesting to investigate the barriers to entrepreneurial intention among Qatari female students by expanding the current theoretical framework to include some cultural factors pertaining to Qatari female students.

Practical implications

This study has implications for statutory bodies involved in promoting entrepreneurship activities. In addition, it offers some suggestions for educational institutions and vocational training centres.

Originality/value

The research confirms the need for more than one theory in explaining the entrepreneurship intention. Another contribution is the context of this study. Qatar’s social, economic and political contexts are totally dissimilar from Eastern or Western set-ups. The study provides some insights on the psychological and institutional barriers among Qatari male students.
An exploration of teachers’ agency and social relationships within dyslexia‐support provision in an English secondary school
Authors: Ross Helen
Published: June 2017

This article explores teachers’ experiences of dyslexia and classroom interventions via lesson observations and semi‐structured interviews. These experiences were analysed through a Bourdieusien lens, based on Jenkins's ‘levels of interaction’, to delineate power relationships inherent in classroom interactions, teachers’ interactions with professionals and institutions, and mechanisms present in teachers’ conceptualisation of ‘self’. Through their conceptualisation of ‘self’ as ‘teachers of dyslexic young people’, it was found that teachers’ classroom interactions acted to reduce social distance between themselves and students. Internally and interactionally, teachers enacted agency and constructed their own social space, through their framing of young people with dyslexia and use of inclusive language with students. Institutionally, teachers were found to be subject to other professions and Government policy, lacking autonomy and capacity to distribute resources, despite their ‘symbolic capital’ as teachers. The ‘level of interaction’ determined teachers’ capacity to act autonomously and freely navigate their own social space.
Making reasonable adjustments for pupils with special educational needs and disabilities: pre‐service teachers’ perceptions of an online support resource
Authors: Morley David , Maher Anthony , Walsh Barbara , Dinning Track , Lloyd Diane , Pratt Andrea
Published: June 2017

The Equality Act called on British schools to ‘avoid as far as possible by reasonable means, the disadvantage which a disabled pupil experiences’. Teachers, therefore, must be creative and flexible in order to meet the needs and optimise the capabilities of all pupils. Using focus group interviews, this article explores the influence of an online resource on pre‐service teachers’ perceptions of making reasonable adjustments for children with special educational needs and disabilities. Pre‐service teachers appeared committed to making reasonable adjustments, with reports of the online resource being particularly influential on their planning and assessing progress. The influence of the resource was less significant on those pre‐service teachers with previous experience of making reasonable adjustments.
Classical Sociology and the First World War: Weber, Durkheim, Simmel and Scheler in the Trenches
Authors: COTESTA VITTORIO
Published: June 2017

The war writings of the founding fathers of modern sociology in France (Durkheim) and Germany (Weber, Simmel, Scheler) on the one hand show the legitimization of the geopolitical situation of each country; on the other, they highlight the image of the relationship between individuals (the combatants) and their country. This article considers some lesser‐known writings by Weber to highlight his will (which was frustrated) to take part in the war and his efforts to sustain his government and German soldiers injured during the fighting through the organization of the Heidelberg Hospital. Together with some of the foremost French intellectuals of his day, Durkheim created an analysis and communication group that produced pamphlets and newspaper articles which are useful in shedding light on the ambiguous stand of the French sociologist over the war. The article then goes on to consider the works by Simmel, in particular, his ‘Die Idee Europa’, an article in which the war was seen as a turning point in history that might have allowed Germany to lead Europe to a greater future. Scheler, for his part, considered the war as a divine punishment for the whole of Europe. As he had it, the God of love would have granted victory to the nation that proved its boundless willingness to sacrifice itself. The author's conclusion is that, with the exception of Simmel in his Soziologie (1908), the fathers of classic sociology did not offer any significant contribution to understanding the war as a social phenomenon.