bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and construction of Keda Space Plasma Experiment (KSPEX) for the investigation of the boundary layer processes of ionospheric depletions
Authors: Liu Yu , Zhang Zhongkai , Lei Jiuhou , Cao Jinxiang , Yu Pengcheng , Zhang Xiao , Xu Liang , Zhao Yaodong
Published: September 2016

In this work, the design and construction of the Keda Space Plasma EXperiment (KSPEX), which aims to study the boundary layer processes of ionospheric depletions, are described in detail. The device is composed of three stainless-steel sections: two source chambers at both ends and an experimental chamber in the center. KSPEX is a steady state experimental device, in which hot filament arrays are used to produce plasmas in the two sources. A Macor-mesh design is adopted to adjust the plasma density and potential difference between the two plasmas, which creates a boundary layer with a controllable electron density gradient and inhomogeneous radial electric field. In addition, attachment chemicals can be released into the plasmas through a tailor-made needle valve which leads to the generation of negative ions plasmas. Ionospheric depletions can be modeled and simulated using KSPEX, and many micro-physical processes of the formation and evolution of an ionospheric depletion can be experimentally studied.
Ab initio potential energy surfaces describing the interaction of CH(X2Π) with H2
Authors: Dagdigian Paul J.
Published: September 2016

We have determined four-dimensional ab initio quasi-diabatic potential energy surfaces describing the interaction of CH(X2Π) with H2, under the assumption of fixed CH and H2 internuclear separations. These calculations employed the multi-reference configuration interaction method [MRCISD+Q(Davidson)]. The computed points were fit to an analytical form suitable for time-independent quantum scattering calculations of rotationally inelastic cross sections and rate constants.
Nitrogen isotopic fractionations in the low temperature (80 K) vacuum ultraviolet photodissociation of N2
Authors: Chakraborty Subrata , Jackson Teresa L. , Rude Bruce , Ahmed Musahid , Thiemens M. H.
Published: September 2016

N2 is a diatomic molecule with complex electronic structure. Interstate crossings are prominent in the high energy domain, introducing significant perturbations to the system. Nitrogen mainly photodissociates in the vacuum ultraviolet (VUV) region of the electromagnetic spectrum through both direct and indirect predissociation. Due to the complexity introduced by these perturbations, the nitrogen isotopic fractionation in N2 photodissociation is extremely hard to calculate, and an experimental approach is required. Here we present new data of N-isotopic fractionation in N2 photodissociation at low temperature (80 K), which shows a distinctly different 15N enrichment profile compared to that at relatively higher temperatures (200 and 300 K). The new data, important to understanding the N-isotopic compositions measured in meteorites and other planetary bodies, are discussed in light of the knowledge of N2 photochemistry and calculated photoabsorption cross sections in the VUV.
Lattice site specific diffusion properties for substitutional and interstitial impurity atoms in ZnO crystals
Authors: Yaqoob Faisal , Huang Mengbing
Published: September 2016

Fundamental understanding of impurity diffusion in crystals remains a challenge due to lack of experimental capabilities for measuring the diffusion properties of atoms according to their substitutional and interstitial lattice locations. With examples of indium and silver in ZnO crystals, we demonstrate an ion beam based method to experimentally determine the energetics and entropy changes in diffusion of substitutional and interstitial impurity atoms. While the interstitial Ag diffuses much faster than the substitutional Ag, as normally expected, the interstitial In migrates slower than the substitutional In, which is attributed to a large negative entropy change (∼−10 kB), possibly caused by the large atomic size of In. The activation energy and the diffusivity pre-exponential factor for the interstitial Ag are significantly enhanced, being more than a factor of two and ∼13 orders of magnitude, respectively, relative to the case for the interstitial In. This implies two different diffusion mechanisms between these two types of interstitial atoms in ZnO crystals: the direct interstitial diffusion mechanism for the interstitial In and the kick-out diffusion mechanism for the interstitial Ag. In addition, the activation energies and the diffusivity prefactors follow the Meyer-Neldel relationship with an excitation energy of ∼92 meV.
Outstanding magnetorheological effect based on discontinuous shear thickening in the presence of a superplastifier molecule
Authors: Bossis G. , Grasselli Y. , Meunier A. , Volkova O.
Published: September 2016

We present the experimental results showing an increase of stress of about 150 kPa for a weak applied magnetic field (H < 10 kA/m) in an aqueous suspension of carbonyl iron particles coated with a superplasticizer molecule used in cement industry. These values, which are several orders of magnitude larger than those classically obtained with magnetorheological suspensions at such low field, can open the way to new applications. These high values result from the triggering of a discontinuous shear thickening (DST) induced by the magnetic field. A phase diagram is presented for a volume fraction of carbonyl iron particles of 62%, showing two domains in the plane, magnetic field versus shear rate. The lower one is liquid of quite low viscosity and the upper one corresponds to a jammed phase where the particles are in frictional contacts and can only move under very high stresses. The transition between the two states is monitored by the ability of the superplasticizer molecule to resist to the compression forces both hydrodynamic and magnetic.
Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field
Authors: Allanson O. , Wilson F. , Neukirch T.
Published: September 2016

We calculate exact one-dimensional collisionless plasma equilibria for a continuum of flux tube models, for which the total magnetic field is made up of the “force-free” Gold-Hoyle magnetic flux tube embedded in a uniform and anti-parallel background magnetic field. For a sufficiently weak background magnetic field, the axial component of the total magnetic field reverses at some finite radius. The presence of the background magnetic field means that the total system is not exactly force-free, but by reducing its magnitude, the departure from force-free can be made as small as desired. The distribution function for each species is a function of the three constants of motion; namely, the Hamiltonian and the canonical momenta in the axial and azimuthal directions. Poisson's equation and Ampère's law are solved exactly, and the solution allows either electrically neutral or non-neutral configurations, depending on the values of the bulk ion and electron flows. These equilibria have possible applications in various solar, space, and astrophysical contexts, as well as in the laboratory.
Influence of the electron velocity spread and the beam width on the efficiency and mode competition in the high-power pulsed gyrotron for 300 GHz band collective Thomson scattering diagnostics in the large helical device
Authors: Dumbrajs O. , Saito T. , Tatematsu Y. , Yamaguchi Y.
Published: September 2016

We present results of a theoretical study of influence of the electron velocity spread and the radial width on the efficiency and mode competition in a 300-kW, 300-GHz gyrotron operating in the TE22,2 mode. This gyrotron was developed for application to collective Thomson scattering diagnostics in the large helical device and 300-kW level high power single TE22,2 mode oscillation has been demonstrated [Yamaguchi et al., J. Instrum. 10, c10002 (2015)]. Effects of a finite voltage rise time corresponding to the real power supply of this gyrotron are also considered. Simulations tracking eight competing modes show that the electron velocity spread and the finite beam width influence not only the efficiency of the gyrotron operation but also the mode competition scenario during the startup phase. A combination of the finite rise time with the electron velocity spread or the finite beam width affects the mode competition scenario. The simulation calculation reproduces the experimental observation of high power single mode oscillation of the TE22,2 mode as the design mode. This gives a theoretical basis of the experimentally obtained high power oscillation with the design mode in a real gyrotron and moreover shows a high power oscillation regime of the design mode.
Adjoint eigenfunctions of temporally recurrent single-spiral solutions in a simple model of atrial fibrillation
Authors: Marcotte Christopher D. , Grigoriev Roman O.
Published: September 2016

This paper introduces a numerical method for computing the spectrum of adjoint (left) eigenfunctions of spiral wave solutions to reaction-diffusion systems in arbitrary geometries. The method is illustrated by computing over a hundred eigenfunctions associated with an unstable time-periodic single-spiral solution of the Karma model on a square domain. We show that all leading adjoint eigenfunctions are exponentially localized in the vicinity of the spiral tip, although the marginal modes (response functions) demonstrate the strongest localization. We also discuss the implications of the localization for the dynamics and control of unstable spiral waves. In particular, the interaction with no-flux boundaries leads to a drift of spiral waves which can be understood with the help of the response functions.
Relative electron density distribution in a low nd helium dc discharge
Authors: Ganguly Biswa N. , Scofield James D.
Published: September 2016

The axial and radial variations of the relative electron density distributions have been measured in an obstructed helium dc discharge by a laser collision induced fluorescence (LCIF) from 4 3D to 2 3P state at 447 nm. For this 1.75 Torr, 6.5 mm gap, 1.6 mA helium obstructed gas discharge, the on-axis LCIF intensity is mostly determined by the neutral atom collision. On the basis of this information, we have plotted the LCIF data to obtain a normalized electron density variation in the inter-electrode volume by plotting the ratio,  I−Ion−axisIon−axis, where I is the radial variation of the LCIF intensity and Ion-axis is the on-axis LCIF intensity. The normalized LCIF data show an annular current density distribution in this obstructed discharge with the current peaking near the radial boundary of the electrodes.
Effect of an axial magnetic field and arc current on the anode current density in diffuse vacuum arcs
Authors: Ma Hui , Geng Yingsan , Liu Zhiyuan , Wang Jianhua , Wang Zhenxing , Zhang Zaiqin
Published: September 2016

The objective of this paper is to measure the effect of an axial magnetic field (AMF) BAMF and arc current on the anode current density in diffuse vacuum arcs. The experimental geometry included a split anode and a butt-type cathode, both with a diameter of 60 mm. The anode surface was divided into a central area and three symmetrically disposed peripheral annular areas. The central area of the split anode had a diameter of 20 mm. The contact material was CuCr25 (25% Cr). The arc current IARC ranged from 4 to 14 kA (rms) at 50 Hz. The opening velocity was 2.4 m/s. The currents of the four areas on the anode contact were measured using four Rogowski coils situated outside the vacuum chamber. An external uniform AMF BAMF ranging from 0 to 110 mT was applied during the experiment. The observed arc modes were recorded by a high-speed charge-coupled device video camera. The experimental results quantitatively reveal that the current density distribution on the anode surface in the diffuse arc mode was not uniform but concentrated in the central area. The current density in the central anode area at the current peak JPeakArea I decreased with increasing BAMF following a power law. For BAMF of 0–110 mT and IARC of 4–14 kA, JPeakArea I = (2.2 IARC + 0.069 IARC2) BAMF−0.22, where JPeakArea I is in A/mm2, BAMF is in mT, and IARC is in kA. Moreover, the current distribution was uneven in the three peripheral areas.
Nucleus-acoustic shock structures in a strongly coupled self-gravitating degenerate quantum plasma
Authors: Mamun A. A. , Amina M. , Schlickeiser R.
Published: September 2016

Nucleus-acoustic (NA) shock structures (SSs) are formed in a strongly coupled self-gravitating degenerate quantum plasma (SCSGDQP) system (e.g., white dwarfs) for the first time. The reductive perturbation method has been employed to identify the basic features of small, but finite amplitude NA SSs. The SCSGDQP is assumed to be composed of strongly coupled non-degenerate heavy nuclei, weakly coupled degenerate light nuclei, and non-relativistically and ultra-relativistically degenerate electrons. It is shown for the first time that the strong correlation among heavy nuclei acts as a source of dissipation and is responsible for the formation of the NA SSs, and that the NA SSs exist with positive (negative) electrostatic (self-gravitational) potential. It also observed that the effects of ultra-relativistically degenerate electrons and of the dynamics and degenerate pressure of light nuclei significantly modify the basic features (viz., speed, amplitude, and width) of the NA SSs. The implications of our results to the astrophysical compact objects like white dwarfs are briefly discussed.
Plasmonic properties of gold nanoparticles on silicon substrates: Understanding Fano-like spectra observed in reflection
Authors: Bossard-Giannesini Léo , Cruguel Hervé , Lacaze Emmanuelle , Pluchery Olivier
Published: September 2016

Gold nanoparticles (AuNPs) are known for their localized surface plasmon resonance (LSPR) that can be measured with UV-visible spectroscopy. AuNPs are often deposited on silicon substrates for various applications, and the LSPR is measured in reflection. In this case, optical spectra are measured by surface differential reflectance spectroscopy (SDRS) and the absorbance exhibits a negative peak. This article studies both experimentally and theoretically on the single layers of 16 nm diameter spherical gold nanoparticles (AuNPs) grafted on silicon. The morphology and surface density of AuNPs were investigated by atomic force microscopy (AFM). The plasmon response in transmission on the glass substrate and in reflection on the silicon substrate is described by an analytical model based on the Fresnel equations and the Maxwell-Garnett effective medium theory (FMG). The FMG model shows a strong dependence to the incidence angle of the light. At low incident angles, the peak appears negatively with a shallow intensity, and at angles above 30°, the usual positive shape of the plasmon is retrieved. The relevance of the FMG model is compared to the Mie theory within the dipolar approximation. We conclude that no Fano effect is responsible for this derivative shape. An easy-to-use formula is derived that agrees with our experimental data.
Atomic-scale quantification of interdiffusion and dopant localization in GeSbTe-based memory devices
Authors: Chae B.-G. , Seol J.-B. , Song J.-H. , Jung W.-Y , Hwang H. , Park C.-G.
Published: September 2016

Fabrication of phase-change memory devices at modest or ambient temperatures leads to nanoscale compositional variations in phase-transition layers, where amorphous-polycrystalline phase change takes place via electrical switching, and can alter the device's performances. Here, by transmission electron microscopy and atom probe tomography, we address that thermal annealing at 400 °C for 20 min induces an elemental interdiffusion in the devices consisting of TiN (top electrode), carbon-doped GeSbTe (phase-transition layer), and TiSiN (bottom heater). With respect to the employed annealing process, the Ge atoms of GeSbTe layer have diffused into TiSiN layer at a given sample volume, while the Ti atoms of TiSiN layer into GeSbTe layer. Furthermore, non-random nature of dopant distribution in the GeSbTe materials leads to a Ti-localization including dopants at the GeSbTe/TiSiN interfaces. Our findings have two important implications: First, the annealing-driven interdiffusion of Ge and Ti is a predominant mechanism responsible for nanoscale compositional variations in GeSbTe layer; second, such an interdiffusion and the resultant dopant localization play a crucial role on the driving force for amorphous-polycrystalline transition of GeSbTe-based memory devices.
Quantum capacitance and charge sensing of a superconducting double dot
Authors: Lambert N. J. , Esmail A. A. , Edwards M. , Pollock F. A. , Lovett B. W. , Ferguson A. J.
Published: September 2016

We study the energetics of a superconducting double dot, by measuring both the quantum capacitance of the device and the response of a nearby charge sensor. We observe different behaviour for odd and even charge states and describe this with a model based on the competition between the charging energy and the superconducting gap. We also find that, at finite temperatures, thermodynamic considerations have a significant effect on the charge stability diagram.
Transparent all-dielectric gradient index waveplates with compact profiles
Authors: Lorente-Crespo M. , Ballesteros G. C. , Mateo-Segura C.
Published: September 2016

Purely dielectric waveplates overcome problems typically associated with metals, e.g., corrosion. However, they are often bulky and/or lossy, substantially reducing their applicability. As the operating frequency shifts towards lower frequencies where compactness is a sought after quality, these problems become even more severe. In this letter, we theoretically demonstrate how to combine axially varying gradient index materials with form birefringence to realize nearly transparent and compact dielectric waveplates. The waveplate is subsequently studied considering a discrete distribution of indexes of refraction. Our results indicate that the number of discretization levels required to perform as the continuous gradient index case is small, which would simplify significantly the fabrication process. As an example, a 0.65λ-thick quarterplate with less than 0.1 dB insertion loss at ∼34 GHz is designed and compared with full-wave simulations, proving an excellent agreement.
Triggering piezoelectricity directly by heat to produce alternating electric voltage
Authors: Liu Yue-Yang , Li Bo-Lin , Zhou Wu-Xing , Chen Ke-Qiu
Published: September 2016

Piezoelectricity has proved itself a promising mechanism for energy conversion and signal sensing by taking advantage of its ability to convert mechanical energy into electricity. Here, we demonstrate that the piezoelectricity in free-standing non-centrosymmetric nanowires can also be triggered directly by heat to produce electricity. The feasibility of the idea is first analyzed by the dynamic theory of crystal lattices and then confirmed by molecular dynamics simulations. The most salient point is that the heat-induced voltage drop across the cross section of the free-standing nanowires alternates periodically with the vibration of the nanowire. Moreover, the electric potential induced by heat here (as large as 0.34 V) is proved to be comparable with the previously reported potentials induced by mechanical energy, and the maximum value can be tuned by controlling the size of the nanowire and the applied heat.
Implementation of a new model of clinical education for regional occupational therapy student clinical placements
Authors: Furness Linda , Pighills Alison C. , Ducat Wendy , Tynan Anna
Published: September 2016

Expansion of occupational therapy education programs has resulted in increased student numbers and demand on clinicians to host clinical placements while also maintaining the delivery of high-quality, safe clinical services to patients. Much of the research about innovative placement models, including student contributions to service delivery, has been conducted in metropolitan areas. Therefore, there is a need to develop models that are suited to regional settings that face diversity of caseload, more generalised occupational therapy roles and variations in patient flow. The aim of the present study was to describe the initial application of the Calderdale Framework in student education in a regional context and look at lessons learnt. The Calderdale Framework provided a structured, clinically governed process whereby occupational therapists were able to determine which tasks could be allocated to students and provided a framework to support student training and competency development. The Calderdale Framework has been used successfully to implement allied health models involving professional skill sharing and delegation of tasks to allied health assistants, but it has not been used in clinical education. Pilot implementation of the Calderdale Framework showed that the model supports quality and safety of student-provided occupational therapy services and that the teaching method provides a platform for student skill development. These results warrant further investigation and are potentially transferrable to student education in other health professions.

What is known about the topic?
The Calderdale Framework provides a systematic method for reviewing skill mix, developing new roles, identifying new ways of working and facilitating service redesign in healthcare environments. It provides a structure for service and task analysis with a focus on developing clinical competencies, but has not been used in clinical education.

What does this paper add?
This paper provides an overview of implementation process, challenges and strategies used in the application of the Calderdale Framework in clinical education.

What are the implications for practitioners?
The Calderdale Framework provides a framework with tools and resources which can be applied to support student learning and student-provided service delivery on clinical placements. Further investigation of the application of the Calderdale Framework in pre-entry student placements is warranted.
Inevitability and containment of replication errors for eukaryotic genome lengths spanning megabase to gigabase
Authors: Al Mamun Mohammed , Albergante Luca , Moreno Alberto , Carrington James T. , Blow J. Julian , Newman Timothy J.
Published: September 2016

Significance

Errors in DNA replication can never be completely avoided. By combining a minimal model that takes into account the positions of replication origins (the regions on the DNA where replication initiates) with experimental evidence, we show that genome size strongly influences the frequency of replicative errors. Our work reveals that (
i
) simple eukaryotes are able to achieve a very low probability of replicative errors by having a moderate number of origins placed at regular intervals; (
ii
) this strategy is ineffective in eukaryotes with larger genomes, such as human, for which replicative errors are inevitable; and (
iii
) in these organisms, even moderate numbers of origins can provide containment of replication errors to very low levels, which can be repaired subsequently.
Developing Bioenergetic-Based Habitat Suitability Curves for Instream Flow Models
Authors: Rosenfeld Jordan , Beecher Hal , Ptolemy Ron
Published: September 2016

Instream flow models link a physical habitat model that predicts flow-related changes in hydraulics to a biological model that predicts the response of fish to altered velocity and depth. Habitat suitability curves (HSCs) based on frequency of habitat use (fish occurrence relative to available habitat) remain the most widely used biological models in habitat simulations. However, in some contexts fish density may be a poor indicator of habitat quality, leading to biased predictions of optimal flow. We explore the use of bioenergetics to derive mechanistic HSCs based on the fundamental energetics of habitat use. Using flow-related changes in production of Coho Salmon Oncorhynchus kisutch smolt as reference data to evaluate model predictions, we found that bioenergetic-based HSCs matched the validation data better than frequency-based HSCs, which systematically underestimated optimal flows. However, biases remained using bioenergetic HSCs, suggesting that habitat suitability may not be independent of discharge as is often assumed. Declining invertebrate drift concentration, increasing temperature, and density dependence of growth at low flows are potential mechanisms of flow-related declines in habitat suitability; measuring these effects and incorporating them into flow models is an important step in further improving model predictions, particularly at low flows.

Received December 3, 2015; accepted May 11, 2016
Synthesis of bovine serum albumin-protected high fluorescence Pt16-nanoclusters and their application to detect sulfide ions in solutions
Authors: Xu Na , Li Hong-Wei , Yue Yuan , Wu Yuqing
Published: September 2016

Highly fluorescent (quantum yield, QY = 17%) Pt16-nanoclusters (Pt16-NCs@BSA) have been prepared via a one-step ultrasonic-assistance method by using cheap and easily available ascorbic acid as reductant and bovine serum albumin (BSA) as a stabilizing agent in aqueous solution. The fluorescence properties of the Pt-NCs@BSA can be easily controlled by optimizing conditions, and the products are extremely stable and could be used for the detection of sulfide ions (S2−) in solutions as a specific luminescence sensor. The present synthesis method is performed in one step, being cost-effective with a particularly short reaction time, which could be extended to the synthesis of other kinds of protein-protected Pt-NCs.
Schubert calculus and torsion explosion
Authors: Williamson Geordie
Published: September 2016

The author observes that certain numbers occurring in Schubert calculus for

SL
n

\text {SL}_n

also occur as entries in intersection forms controlling decompositions of Soergel bimodules in higher rank. These numbers grow exponentially. This observation gives many counter-examples to the expected bounds in Lusztig’s conjecture on the characters of simple rational modules for

SL
n

\text {SL}_n

over fields of positive characteristic. The examples also give counter-examples to the James conjecture on decomposition numbers for symmetric groups.
The Bending Rigidity of Mitotic Chromosomes
Authors: Poirier Michael G. , Eroglu Sertac , Marko John F.
Published: September 2016

The bending rigidities of mitotic chromosomes isolated from cultured N. viridescens (newt) and Xenopusepithelial cells were measured by observing their spontaneous thermal bending fluctuations. When combined with simultaneous measurement of stretching elasticity, these measurements constrain models for higher order mitotic chromosome structure. We measured bending rigidities of B ∼10−22N · m2for newt and ∼10−23N · m2forXenopus chromosomes extracted from cells. A similar bending rigidity was measured for newt chromosomes in vivo by observing bending fluctuations in metaphase-arrested cells. Following each bending rigidity measurement, a stretching (Young's) modulus of the same chromosome was measured in the range of 102to 103Pa for newt and Xenopus chromosomes. For each chromosome, these values of B and Y are consistent with those expected for a simple elastic rod, B ≈ YR4, where R is the chromosome cross-section radius. Our measurements rule out the possibility that chromosome stretching and bending elasticity are principally due to a stiff central core region and are instead indicative of an internal structure, which is essentially homogeneous in its connectivity across the chromosome cross-section.
Novel ATPase of SNF2-like Protein Family Interacts with Androgen Receptor and Modulates Androgen-dependent Transcription
Authors: Rouleau Nathalie , Domans'kyi Andrii , Reeben Mati , Moilanen Anu-Maarit , Havas Kristina , Kang Zhigang , Owen-Hughes Tom , Palvimo Jorma J. , Jänne Olli A.
Published: September 2016

Nuclear receptors, including the androgen receptor (AR), regulate target cell transcription through interaction with auxiliary proteins to modify chromatin structure. We describe herein a novel AR-interacting protein, termed ARIP4, that has structural features typical of the SNF2-like protein family. With regard to the Snf2 domain, the closest homolog of ARIP4 is the ATRX protein. ARIP4 is a nuclear protein and comprises 1466 amino acids. It interacts with AR in vitro and in cultured yeast and mammalian cells. ARIP4 can be labeled with 8-azido-[γ-32P]ATP and exhibits DNA-dependent ATPase activity. Like several ATP-dependent chromatin remodeling proteins, ARIP4 generates superhelical torsion within linear DNA fragments in an ATP-dependent manner. With a stably integrated target promoter, ARIP4 elicits a modest enhancement of AR-dependent transactivation. In transient cotransfection assays, ARIP4 modulates AR function in a promoter-dependent manner; it enhances receptor activity on minimal promoters, but does not activate more complex promoters. ARIP4 mutants devoid of ATPase activity fail to alter DNA topology and behave as trans-dominant negative regulators of AR function in transient assays.
Thrombospondin 2 Inhibits Microvascular Endothelial Cell Proliferation by a Caspase-independent Mechanism
Authors: Armstrong Lucas C. , Björkblom Benny , Hankenson Kurt D. , Siadak Anthony W. , Stiles Charlotte E. , Bornstein Paul
Published: September 2016

The matricellular protein thrombospondin 2 (TSP2) regulates a variety of cell–matrix interactions. A prominent feature of TSP2-null mice is increased microvascular density, particularly in connective tissues synthesized after injury. We investigated the cellular basis for the regulation of angiogenesis by TSP2 in cultures of murine and human fibroblasts and endothelial cells. Fibroblasts isolated from murine and human dermis synthesize TSP2 mRNA and secrete significant amounts of immunoreactive TSP2, whereas endothelial cells from mouse lung and human dermis did not synthesize TSP2 mRNA or protein. Recombinant mouse TSP2 inhibited growth of human microvascular endothelial cells (HMVECs) mediated by basic fibroblast growth factor, insulin-like growth factor-1, epidermal growth factor, and vascular endothelial growth factor (VEGF). HMVECs exposed to TSP2 in the presence of these growth factors had a decreased proportion of cells in S and G2/M phases. HMVECs cultured with a combination of basic fibroblast growth factor, insulin-like growth factor-1, and epidermal growth factor displayed an increased proportion of nonviable cells in the presence of TSP2, but the addition of VEGF blocked this TSP2-mediated impairment of cell viability. TSP2-mediated inhibition of DNA synthesis by HMVECs in the presence of VEGF was not affected by the broad-spectrum caspase inhibitor zVAD-fmk. Similar findings were obtained with TSP1. Taken together, these observations indicate that either TSP2 or TSP1 can inhibit HMVEC proliferation by inhibition of cell cycle progression and induction of cell death, but the mechanisms responsible for TSP2-mediated inhibition of cell cycle progression are independent from those leading to cell death.
A novel role for yeast casein kinases in glucose sensing and signaling
Authors: Snowdon Chris , Johnston Mark
Published: September 2016

Yeasts have sophisticated signaling pathways for sensing glucose, their preferred carbon source, to regulate its uptake and metabolism. One of these is the sensor/receptor-repressor (SRR) pathway, which detects extracellular glucose and transmits an intracellular signal that induces expression of HXT genes. The yeast casein kinases (Ycks) are key players in this pathway. Our model of the SRR pathway had the Ycks functioning downstream of the glucose sensors, transmitting the signal from the sensors to the Mth1 and Std1 corepressors that are required for repression of HXT gene expression. However, we found that overexpression of Yck1 fails to restore glucose signaling in a glucose sensor mutant. Conversely, overexpression of a glucose sensor suppresses the signaling defect of a yck mutant. These results suggest that the Ycks act upstream or at the level of the glucose sensors. Indeed, we found that the glucose sensor Rgt2 is phosphorylated on Yck consensus sites in its C-terminal tail in a Yck-dependent manner and that this phosphorylation is required for corepressor binding and ultimately HXT expression. This leads to a revised model of the SRR pathway in which the Ycks prime a site on the cytoplasmic tails of the glucose sensors to promote binding of the corepressors.
Pilonidal Sinus Disease: 10 Steps to Optimize Care
Authors: Harris Connie , Sibbald R. Gary , Mufti Asfandyar , Somayaji Ranjani
Published: September 2016

PURPOSE:

To present a 10-step approach to the assessment and treatment of pilonidal sinus disease (PSD) and related wounds based on the Harris protocol, expert opinion, and a current literature review.

TARGET AUDIENCE:

This continuing education activity is intended for physicians and nurses with an interest in skin and wound care.

OBJECTIVES:

After participating in this educational activity, the participant should be better able to:

Pilonidal sinus disease (PSD) is a common problem in young adults and particularly in males with a deep natal or intergluteal cleft and coarse body hair. An approach to an individual with PSD includes the assessment of pain, activities of daily living, the pilonidal sinus, and natal cleft. Local wound care includes the management of infection (if present), along with appropriate debridement and moisture management. Treatment is optimized with patient empowerment to manage the wound and periwound environment (cleansing, dressing changes, decontamination, hair removal, minimizing friction). Self-care education includes the recognition of recurrences or infection. Early surgical intervention of these wounds is often necessary for successful outcomes. Pilonidal sinus healing by secondary intention often takes weeks to months; however, the use of the Harris protocol may decrease healing times. A number of new surgical approaches may accelerate healing. Surgical closure by primary intention is often associated with higher recurrence rates. Expert opinion in this article is combined with an evidence-based literature review. The authors have tabulated 10 key steps from the Harris protocol, including a review of the surgical techniques to improve PSD patient outcomes.
Accuracy of an Extubation Readiness Test in Predicting Successful Extubation in Children With Acute Respiratory Failure From Lower Respiratory Tract Disease*
Authors: Faustino Edward Vincent S. , Gedeit Rainer , Schwarz Adam J. , Asaro Lisa A. , Wypij David , Curley Martha A.Q.
Published: September 2016

Objective:

Identifying children ready for extubation is desirable to minimize morbidity and mortality associated with prolonged mechanical ventilation and extubation failure. We determined the accuracy of an extubation readiness test (Randomized Evaluation of Sedation Titration for Respiratory Failure extubation readiness test) in predicting successful extubation in children with acute respiratory failure from lower respiratory tract disease.

Design:

Secondary analysis of data from the Randomized Evaluation of Sedation Titration for Respiratory Failure clinical trial, a pediatric multicenter cluster randomized trial of sedation.

Setting:

Seventeen PICUs in the intervention arm.

Patients:

Children 2 weeks to 17 years receiving invasive mechanical ventilation for lower respiratory tract disease.

Intervention:

Extubation readiness test in which spontaneously breathing children with oxygenation index less than or equal to 6 were placed on Fio
2 of 0.50, positive end-expiratory pressure of 5 cm H2O, and pressure support.

Measurements and Main Results:

Of 1,042 children, 444 (43%) passed their first extubation readiness test. Of these, 295 (66%) were extubated within 10 hours of starting the extubation readiness test, including 272 who were successfully extubated, for a positive predictive value of 92%. Among 861 children who were extubated for the first time within 10 hours of performing an extubation readiness test, 788 passed their extubation readiness test and 736 were successfully extubated for a positive predictive value of 93%. The median time of day for extubation with an extubation readiness test was 12:15 hours compared with 14:54 hours for extubation without an extubation readiness test within 10 hours (p < 0.001).

Conclusions:

In children with acute respiratory failure from lower respiratory tract disease, an extubation readiness test, as described, should be considered at least daily if the oxygenation index is less than or equal to 6. If the child passes the extubation readiness test, there is a high likelihood of successful extubation.
Readmissions to Intensive Care: A Prospective Multicenter Study in Australia and New Zealand*
Authors: Santamaria John D. , Duke Graeme J. , Pilcher David V. , Cooper D. James , Moran John , Bellomo Rinaldo
Published: September 2016

Objectives:

To determine factors independently associated with readmission to ICU and the independent association of readmission with subsequent mortality.

Design:

Prospective multicenter observational study.

Setting:

Forty ICUs in Australia and New Zealand.

Patients:

Consecutive adult patients discharged alive from ICU to hospital wards between September 2009 and February 2010.

Interventions:

Measurement of hospital mortality.

Measurements and Main Results:

We studied 10,210 patients and 674 readmissions. The median age was 63 years (interquartile range, 49–74), and 6,224 (61%) were male. The majority of readmissions were unplanned (84.1%) but only deemed preventable in a minority (8.9%) of cases. Time to first readmission was shorter for unplanned than planned readmission (3.2 vs 6.9 d; p < 0.001). Primary diagnosis changed between admission and readmission in the majority of patients (60.2%) irrespective of planned (58.2%) or unplanned (60.6%) status. Using recurrent event analysis incorporating patient frailty, we found no association between readmissions and hospital survival (hazard ratios: first readmission 0.88, second readmission 0.90, third readmission 0.44; p > 0.05). In contrast, age (hazard ratio, 1.03), a medical diagnosis (hazard ratio, 1.43), inotrope use (hazard ratio, 3.47), and treatment limitation order (hazard ratio, 17.8) were all independently associated with outcome.

Conclusions:

In this large prospective study, readmission to ICU was not an independent risk factor for mortality.
Cumulative Evidence of Randomized Controlled and Observational Studies on Catheter-Related Infection Risk of Central Venous Catheter Insertion Site in ICU Patients: A Pairwise and Network Meta-Analysis
Authors: Arvaniti Kostoula , Lathyris Dimitrios , Blot Stijn , Apostolidou-Kiouti Fani , Koulenti Despoina , Haidich Anna-Bettina
Published: September 2016

Background:

Selection of central venous catheter insertion site in ICU patients could help reduce catheter-related infections. Although subclavian was considered the most appropriate site, its preferential use in ICU patients is not generalized and questioned by contradicted meta-analysis results. In addition, conflicting data exist on alternative site selection whenever subclavian is contraindicated.

Objective:

To compare catheter-related bloodstream infection and colonization risk between the three sites (subclavian, internal jugular, and femoral) in adult ICU patients.

Data Source:

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled trials, CINAHL, and ClinicalTrials.gov.

Study Selection:

Eligible studies were randomized controlled trials and observational ones.

Data Extraction:

Extracted data were analyzed by pairwise and network meta-analysis.

Data Synthesis:

Twenty studies were included; 11 were observational, seven were randomized controlled trials for other outcomes, and two were randomized controlled trials for sites. We evaluated 18,554 central venous catheters: 9,331 from observational studies, 5,482 from randomized controlled trials for other outcomes, and 3,741 from randomized controlled trials for sites. Colonization risk was higher for internal jugular (relative risk, 2.25 [95% CI, 1.84–2.75]; I
2 = 0%) and femoral (relative risk, 2.92 [95% CI, 2.11–4.04]; I
2 = 24%), compared with subclavian. Catheter-related bloodstream infection risk was comparable for internal jugular and subclavian, higher for femoral than subclavian (relative risk, 2.44 [95% CI, 1.25–4.75]; I
2 = 61%), and lower for internal jugular than femoral (relative risk, 0.55 [95% CI, 0.34–0.89]; I
2 = 61%). When observational studies that did not control for baseline characteristics were excluded, catheter-related bloodstream infection risk was comparable between the sites.

Conclusions:

In ICU patients, internal jugular and subclavian may, similarly, decrease catheter-related bloodstream infection risk, when compared with femoral. Subclavian could be suggested as the most appropriate site, whenever colonization risk is considered and not, otherwise, contraindicated. Current evidence on catheter-related bloodstream infection femoral risk, compared with the other sites, is inconclusive.
Vitamin D Deficiency in Human and Murine Sepsis*
Authors: Parekh Dhruv , Patel Jaimin M. , Scott Aaron , Lax Sian , Dancer Rachel C. A. , D’Souza Vijay , Greenwood Hannah , Fraser William D. , Gao Fang , Sapey Elizabeth , Perkins Gavin D. , Thickett David R.
Published: September 2016

Objectives:

Vitamin D deficiency has been implicated as a pathogenic factor in sepsis and ICU mortality but causality of these associations has not been demonstrated. To determine whether sepsis and severe sepsis are associated with vitamin D deficiency and to determine whether vitamin D deficiency influences the severity of sepsis.

Design, Setting, and Patients:

Sixty-one patients with sepsis and severe sepsis from two large U.K. hospitals and 20 healthy controls were recruited. Murine models of cecal ligation and puncture and intratracheal lipopolysaccharide were undertaken in normal and vitamin D deficient mice to address the issue of causality.

Measurements and Main Results:

Patients with severe sepsis had significantly lower concentrations of 25-hydroxyvitamin D3 than patients with either mild sepsis or age-matched healthy controls (15.7 vs 49.5 vs 66.5 nmol/L; p = 0.0001). 25-hydroxyvitamin D3 concentrations were significantly lower in patients who had positive microbiologic culture than those who were culture negative (p = 0.0023) as well as those who died within 30 days of hospital admission (p = 0.025). Vitamin D deficiency in murine sepsis was associated with increased peritoneal (p = 0.037), systemic (p = 0.019), and bronchoalveolar lavage (p = 0.011) quantitative bacterial culture. This was associated with reduced local expression of the cathelicidin-related antimicrobial peptide as well as evidence of defective macrophage phagocytosis (p = 0.029). In the intratracheal lipopolysaccharide model, 1,500 IU of intraperitoneal cholecalciferol treatment 6 hours postinjury reduced alveolar inflammation, cellular damage, and hypoxia.

Conclusions:

Vitamin D deficiency is common in severe sepsis. This appears to contribute to the development of the condition in clinically relevant murine models and approaches to correct vitamin D deficiency in patients with sepsis should be developed.
Basal Cell Carcinoma of the Dorsal Foot: An Update and Comprehensive Review of the Literature
Authors: Loh Tiffany Y. , Rubin Ashley G. , Jiang Shang I Brian
Published: September 2016

BACKGROUND

Ultraviolet radiation is a well-known risk factor for basal cell carcinoma (BCC). Therefore, the high incidence of BCCs in sun-exposed areas such as the head and neck is unsurprising. However, unexpectedly, BCCs on the sun-protected dorsal foot have also been reported, and tumor occurrence here suggests that other factors besides ultraviolet radiation may play a role in BCC pathogenesis. Because only few dorsal foot BCCs have been reported, data on their clinical features and management are limited.

OBJECTIVE

To perform an updated review of the literature on clinical characteristics and treatment of dorsal foot BCCs.

METHODS

We conducted a comprehensive literature review by searching the PubMed database with the key phrases “basal cell carcinoma dorsal foot,” “basal cell carcinoma foot,” and “basal cell carcinoma toe.”

RESULTS

We identified 20 cases of dorsal foot BCCs in the literature, 17 of which had sufficient data for analysis. Only 1 case was treated with Mohs micrographic surgery. We present 8 additional cases of dorsal foot BCCs treated with Mohs micrographic surgery.

CONCLUSION

Basal cell carcinomas on the dorsal foot are rare, and potential risk factors include Caucasian descent and personal history of skin cancer. Mohs micrographic surgery seems to be an effective treatment option.
A Mechanistic Model of Platelet-Rich Plasma Treatment for Androgenetic Alopecia
Authors: Gupta Aditya K. , Carviel Jessie
Published: September 2016

BACKGROUND

Platelet-rich plasma (PRP) therapy is a novel procedure used to treat androgenetic alopecia (AGA).

OBJECTIVE

Propose a mechanism of action of PRP therapy for AGA.

METHODS AND MATERIALS

A thorough literature search including PRP research for AGA therapy as well as PRP research in other areas of medicine was conducted.

RESULTS

A mechanistic model for the action of PRP on the hair follicle was created.

CONCLUSION

Platelet-rich plasma therapy stimulates hair growth through the promotion of vascularization and angiogenesis, as well as encourages hair follicles to enter and extend the duration of the anagen phase of the growth cycle. The process is accomplished through growth factor-mediated increased activation of wingless (Wnt)/β-catenin, extracellular signaling regulated kinase (ERK), and protein kinase B (Akt) signaling pathways, which leads to the necessary cellular proliferation and differentiation.
Patient Activation in Acute Decompensated Heart Failure
Authors: Dunlay Shannon M. , Griffin Joan M. , Redfield Margaret M. , Roger Véronique L.
Published: September 2016

Background:

Recent data suggest that patient activation, or having the knowledge, skills, and confidence to engage and manage one's own health, favorably impacts patient behaviors and health outcomes. However, the role of activation in patients with heart failure is unknown.

Objectives:

The aims of this study are to measure the level of activation of patients hospitalized with acute decompensated heart failure (ADHF) and to determine whether activation is associated with in-hospital and early postdischarge outcomes.

Methods:

We prospectively recruited Southeastern Minnesota residents hospitalized at Mayo Clinic hospitals with ADHF from January 2014 to July 2015. Activation was measured using the Patient Activation Measure questionnaire.

Results:

Among the 302 patients enrolled, the mean age was 77.3 years, 57.3% were men, and 46.8% had preserved ejection fraction. The median (25th–75th percentile) length of stay was 4 (3–7) days. In total, 7 (2.3%) patients died before discharge. Most survivors were discharged to home (73.6%) or skilled nursing facilities (23.7%). The number of patients in each activation level from highest to lowest was 9 (3.0%), 121 (40.1%), 122 (40.4%), and 50 (16.6%). Patients with lower activation were older, were less educated, had lower patient satisfaction, and had worse health literacy. They were more often discharged to skilled nursing facilities and had higher 30-day mortality, although 30-day readmission did not differ by activation.

Conclusions:

Patients hospitalized with ADHF with lower activation are less satisfied, have worse health literacy, more often require skilled care, and are at increased risk for early postdischarge mortality. Activation can be easily measured and may help clinicians identify high-risk patients.