bluuebunny/crossref_metadata_2025 huggingface dataset:
Corticosteroids and occurrence of and mortality from infections in severe alcoholic hepatitis: a meta‐analysis of randomized trials
Authors: Hmoud Bashar S. , Patel Kershaw , Bataller Ramon , Singal Ashwani K.
Published: August 2015

Background & Aims

Prednisolone is the first‐line therapy for severe alcoholic hepatitis (AH). Patients with severe alcoholic hepatitis often develop severe infections that negatively impact short‐term prognosis.

Methods

We performed this meta‐analysis to assess the effect of corticosteroids on the occurrence of and mortality from infections in patients with severe alcoholic hepatitis. Randomized controlled trials examining the use of corticosteroids in severe alcoholic hepatitis and reporting data on infection rates and mortality were included. Random effects model was used to pool the data comparing arms with and without steroids for the occurrence of infection, 28‐day mortality and cause specific mortality.

Results

Of 1062 patients (528 steroids treated) without infection at baseline from 12 studies, infection was reported in 213 (113 steroids treated) patients without differences comparing arms with and without steroids (OR: 0.98; CI: 0.49–1.94). However, frequency was higher for occurrence of fungal infections among steroid‐treated patients (eight of 528 vs. one of 534; P = 0.02). Steroids provided mortality benefit at 28 days (OR: 0.55; CI: 0.34–0.90) mainly for liver failure‐related death (OR: 0.46; CI: 0.24–0.87) without differences on mortality from infection (OR: 1.19; CI: 0.38–3.73) or gastrointestinal bleeding (OR: 0.90; CI: 0.43–1.87). Three of nine patients with fungal infections died, all in corticosteroid arm.

Conclusions

Corticosteroids do not increase occurrence of or mortality from bacterial infections in patients with severe alcoholic hepatitis. Further studies are needed to develop strategies of reducing the risk of fungal infection with use of steroids for patients with severe alcoholic hepatitis.
Particle–Fluid–Structure Interaction for Debris Flow Impact on Flexible Barriers
Authors: Leonardi Alessandro , Wittel Falk K. , Mendoza Miller , Vetter Roman , Herrmann Hans J.
Published: August 2015

Flexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, the development of a numerical tool for the rational design of such structures is still a challenge. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the finite element method to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of the flow of a fluid‐grain mixture, using two conveniently coupled solvers: the discrete element method governs the motion of the grains, while the free‐surface non‐Newtonian fluid phase is solved using the lattice Boltzmann method. Simulations on realistic geometries show the dependence of the momentum transfer on the barrier on the composition of the debris flow, challenging typical assumptions made during the design process today. In particular, we demonstrate that both grains and fluid contribute in a nonnegligible way to the momentum transfer. Moreover, we show how the flexibility of the barrier reduces its vulnerability to structural collapse, and how the stress is distributed on its fabric, highlighting potential weak points.
GacA is essential for Group A Streptococcus and defines a new class of monomeric dTDP‐4‐dehydrorhamnose reductases (RmlD)
Authors: van der Beek Samantha L. , Le Breton Yoann , Ferenbach Andrew T. , Chapman Robert N. , van Aalten Daan M. F. , Navratilova Iva , Boons Geert‐Jan , McIver Kevin S. , van Sorge Nina M. , Dorfmueller Helge C.
Published: August 2015

The sugar nucleotide dTDP‐L‐rhamnose is critical for the biosynthesis of the Group A Carbohydrate, the molecular signature and virulence determinant of the human pathogen Group A Streptococcus (GAS). The final step of the four‐step dTDP‐L‐rhamnose biosynthesis pathway is catalyzed by dTDP‐4‐dehydrorhamnose reductases (RmlD). RmlD from the Gram‐negative bacterium Salmonella is the only structurally characterized family member and requires metal‐dependent homo‐dimerization for enzymatic activity. Using a biochemical and structural biology approach, we demonstrate that the only RmlD homologue from GAS, previously renamed GacA, functions in a novel monomeric manner. Sequence analysis of 213 Gram‐negative and Gram‐positive RmlD homologues predicts that enzymes from all Gram‐positive species lack a dimerization motif and function as monomers. The enzymatic function of GacA was confirmed through heterologous expression of gacA in a S. mutans rmlD knockout, which restored attenuated growth and aberrant cell division. Finally, analysis of a saturated mutant GAS library using Tn‐sequencing and generation of a conditional‐expression mutant identified gacA as an essential gene for GAS. In conclusion, GacA is an essential monomeric enzyme in GAS and representative of monomeric RmlD enzymes in Gram‐positive bacteria and a subset of Gram‐negative bacteria. These results will help future screens for novel inhibitors of dTDP‐L‐rhamnose biosynthesis.
Surface display of Aggregatibacter actinomycetemcomitans autotransporter Aae and dispersin B hybrid act as antibiofilm agents
Authors: Ragunath C. , DiFranco K. , Shanmugam M. , Gopal P. , Vyas V. , Fine D.H. , Cugini C. , Ramasubbu N.
Published: August 2015

Among the various proteins expressed by the periodontopathogen Aggregatibacter actinomycetemcomitans, two proteins play important roles for survival in the oral cavity. The autotransporter Aae facilitates the attachment of the pathogen to oral epithelial cells, which act as a reservoir, while the biofilm‐degrading glycoside hydrolase dispersin B facilitates the movement of daughter cells from the mature biofilm to a new site. The objective of this study was to use the potential of these two proteins to control biofilms. To this end, we generated a hybrid construct between the Aae C‐terminal translocating domain and dispersin B, and mobilized it into Escherichia coli Rosetta (DE3) pLysS cells. Immunofluorescence analysis of the modified E. coli cells confirmed the presence of dispersin B on the surface. Further, the membrane localization of the displayed dispersin B was confirmed with Western blot analysis. The integrity of the E. coli cells displaying the dispersin B was confirmed through FACS analysis. The hydrolytic activity of the surface‐displayed dispersin B was confirmed by using 4‐methylumbelliferyl‐β‐d‐glucopyranoside as the substrate. The detachment ability of the dispersin B surface‐displaying E. coli cells was shown using Staphylococcus epidermidis and Actinobacillus pleuropneumoniae biofilms in a microtiter assay. We concluded that the Aae β‐domain is sufficient to translocate foreign enzymes in the native folded form and that the method of Aae‐mediated translocation of surface displayed enzymes might be useful for control of biofilms.
Novel Therapeutic Options for the Treatment of Mineral Metabolism Abnormalities in End Stage Renal Disease
Authors: Kendrick Jessica , Chonchol Michel
Published: August 2015

Abnormalities in mineral metabolism are a universal complication in dialysis patients and are associated with an increased risk of cardiovascular disease and mortality. Hyperphosphatemia, increased fibroblast growth factor 23 levels and secondary hyperparathyroidism are all strongly associated with adverse outcomes in end stage renal disease (ESRD) and most treatment strategies target these parameters. Over the past few years, new therapies have emerged for the treatment of abnormalities of mineral metabolism in ESRD and many are promising. This article will review these new therapeutic options including the potential advantages and disadvantages compared to existing therapies.
Conservation of Mass: An Important Tool in Renal Research
Authors: Sargent John A.
Published: August 2015

The dialytic treatment of end‐stage renal disease (ESRD) patients is based on control of solute concentrations and management of fluid volume. The application of the principal of conservation of mass, or mass balance, is fundamental to the study of such treatment and can be extended to chronic kidney disease (CKD) in general. This review discusses the development and use of mass conservation and transport concepts, incorporated into mathematical models. These concepts, which can be applied to a wide range of solutes of interest, represent a powerful tool for quantitatively guided studies of dialysis issues currently and into the future. Incorporating these quantitative concepts in future investigations is key to achieving positive control of known solutes, and in the analysis of such studies; to relate future research to known results of prior studies; and to help in the understanding of the obligatory physiological perturbations that result from dialysis therapy.
Does the Quality of Investment Protection Affect FDI Flows to Developing Countries? Evidence from Latin America
Authors: Dixon Jay , Haslam Paul Alexander
Published: August 2015

Studies on the impact of international investment agreements (IIAs), including bilateral investment treaties (BITs), on foreign direct investment (FDI) inflows have been inconclusive. This paper contributes to the debate about the effectiveness of IIAs using an original database that differentiates between investment agreements according to the quality of investor protection, and which covers a wide variety of trade and investment agreements signed and ratified in the Americas. We find evidence that in the least likely case of south–south FDI flows, high‐quality international investment treaties have a demonstrable effect on foreign direct investment inflows. Moreover, international investment agreements appear to be most effective in a context of deeper economic integration. That is, they work better when they provide higher quality protection to investors and when they are combined with other preferential economic integration agreements, such as trade agreements.
Retrospective analysis for treatment of naïve canine multicentric lymphoma with a 15‐week, maintenance‐freeCHOPprotocol
Authors: Curran K. , Thamm D. H.
Published: August 2015

Standard of care treatment of dogs with multicentric lymphoma includes combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP); however, owners may be hesitant to commit the resources necessary to complete a lengthy, multi‐drug protocol. One hundred thirty‐four client‐owned dogs with multicentric lymphoma were treated with a 15‐weekCHOPchemotherapy protocol. The overall response rate was 98% with 104 dogs experiencing a complete response (CR). The median progression‐free survival (PFS) time for all dogs was 176 days, and the median disease‐specific overall survival time was 311 days. Prognostic factors identified on multivariate analysis as significant forPFSincluded substage, immunophenotype, hospitalization for adverse events, need for dose reduction, presence of neutrophilia at diagnosis, presence of anemia and experiencing aCRas best response to therapy. In conclusion, this protocol may be a viable alternative toCHOPprotocols using a larger number of treatments.
Effects of muscle composition and architecture on specific strength in obese older women
Authors: Rastelli F. , Capodaglio P. , Orgiu S. , Santovito C. , Caramenti M. , Cadioli M. , Falini A. , Rizzo G. , Lafortuna C. L.
Published: August 2015

New Findings

What is the central question of this study?

Do obesity‐specific factors affect skeletal muscle performance in older individuals?

What is the main finding and its importance?

Older obese women have a larger quadriceps femoris size but develop lower tension per unit of skeletal muscle than their normal‐weight counterparts.

Muscle impairment and excess body mass are very common among older people. Given that the effect of obesity on strength production has scarcely been studied in older individuals, we analysed functional and structural characteristics of quadriceps femoris (QF) in obese (OB) and normal‐weight (NW) older women with comparable habitual physical activity. In five OB (body mass index 36.8 ± 1.9 kg m−2, age 72.4 ± 2.3 years) and six NW well‐functioning older women (body mass index 24.3 ± 1.8 kg m−2, age 72.7 ± 1.9 years), peak knee‐extension torque (KET) was measured in isometric (90 deg knee flexion) and isokinetic conditions (240, 180, 120 and 60 deg s−1). Mid‐thigh QF cross‐sectional area (CSA) and muscle tissue fat content (MF%) were determined with magnetic resonance imaging (Dixon sequence). Muscle fascicle length and pennation angle (PA) were assessed with ultrasonography for each muscle belly of the QF (vastus lateralis, vastus intermedius, rectus femoris and vastus intermedius). Despite similar values of KET, CSA was 17.0% larger in OB than in NW women (P < 0.05), so that KET/CSA was significantly lower (P < 0.05) in OB women. Compared with NW women, OB women had 28.7% higher MF% (P < 0.05) and 24.9% higher average PA (P < 0.05), while fascicle length was similar. Overall, isometric KET/CSA was negatively affected by both MF% (P < 0.05) and PA (P < 0.05), while isokinetic KET/CSA was negatively affected only by MF% (P < 0.01). Muscle composition and architecture seem to be important determinants of KET/CSA in elderly women. In fact, owing to the effect of obesity overload, OB women have a larger QF size than NW women, but unfavourable muscle composition and architecture. The higher MF% and steeper PA observed in OB women are associated with reduced levels of muscle specific strength.
Increase in pulmonary blood flow at birth: role of oxygen and lung aeration
Authors: Lang Justin A.R. , Pearson James T. , Binder‐Heschl Corinna , Wallace Megan J. , Siew Melissa L. , Kitchen Marcus J. , te Pas Arjan B. , Fouras Andreas , Lewis Robert A. , Polglase Graeme R. , Shirai Mikiyasu , Hooper Stuart B.
Published: August 2015

Key points

There is no well‐established, direct correlation between local aeration and perfusion in the lungs immediately following birth.

In a new study of simultaneous X‐ray imaging and angiography in near‐term rabbits, we investigated the relative contributions of lung aeration and increased oxygenation in the increase in pulmonary perfusion at birth.

We demonstrated that partial lung aeration induces a global increase in pulmonary blood flow that is independent of changes in inspired oxygen.

These results show that mechanisms unrelated to oxygenation or the spatial relationships that match ventilation to perfusion initiate the large increase in pulmonary blood flow at birth.

Lung aeration stimulates the increase in pulmonary blood flow (PBF) at birth, but the spatial relationships between PBF and lung aeration and the role of increased oxygenation remain unclear. Using simultaneous phase‐contrast X‐ray imaging and angiography, we have investigated the separate roles of lung aeration and increased oxygenation in PBF changes at birth using near‐term (30 days of gestation) rabbit kits (n = 18). Rabbits were imaged before ventilation, then the right lung was ventilated with 100% nitrogen (N2), air or 100% O2 (oxygen), before all kits were switched to ventilation in air, followed by ventilation of both lungs using air. Unilateral ventilation of the right lung with 100% N2 significantly increased heart rate (from 69.4 ± 4.9 to 93.0 ± 15.0 bpm), the diameters of both left and right pulmonary axial arteries, number of visible vessels in both left and right lungs, relative PBF index in both pulmonary arteries, and reduced bolus transit time for both left and right axial arteries (from 1.34 ± 0.39 and 1.81 ± 0.43 s to 0.52 ± 0.17 and 0.89 ± 0.21 s in the left and right axial arteries, respectively). Similar changes were observed with 100% oxygen, but increases in visible vessel number and vessel diameter of the axial arteries were greater in the ventilated right lung during unilateral ventilation. These findings confirm that PBF increase at birth is not spatially related to lung aeration and that the increase in PBF to unventilated regions is unrelated to oxygenation, although oxygen can potentiate this increase.
Verification Assessment of Piston Boundary Conditions for Lagrangian Simulation of Compressible Flow Similarity Solutions
Authors: Ramsey Scott D. , Ivancic Philip R. , Lilieholm Jennifer F.
Published: August 2015

This work is concerned with the use of similarity solutions of the compressible flow equations as benchmarks or verification test problems for finite-volume compressible flow simulation software. In practice, this effort can be complicated by the infinite spatial/temporal extent of many candidate solutions or “test problems.” Methods can be devised with the intention of ameliorating this inconsistency with the finite nature of computational simulation; the exact strategy will depend on the code and problem archetypes under investigation. For example, self-similar shock wave propagation can be represented in Lagrangian compressible flow simulations as rigid boundary-driven flow, even if no such “piston” is present in the counterpart mathematical similarity solution. The purpose of this work is to investigate in detail the methodology of representing self-similar shock wave propagation as a piston-driven flow in the context of various test problems featuring simple closed-form solutions of infinite spatial/temporal extent. The closed-form solutions allow for the derivation of similarly closed-form piston boundary conditions (BCs) for use in Lagrangian compressible flow solvers. The consequences of utilizing these BCs (as opposed to directly initializing the self-similar solution in a computational spatial grid) are investigated in terms of common code verification analysis metrics (e.g., shock strength/position errors and global convergence rates).
On the Scalability of Model-Scale Ice Experiments
Authors: Franz von Bock und Polach Rüdiger U. , Ehlers Sören
Published: August 2015

Ice model tests are a frequently used mean to assess and predict the performance of ships and structures in ice. The model ice composition is adjusted to comply with Froude and Cauchy similitude. Recent research indicates that the internal mechanics of Aalto model-scale ice and sea ice differ significantly. This consequently limits the scalability and challenges state-of-the-art scaling procedures. This paper presents a qualitative assessment on selected topics to assess the differences between model-scale ice and sea ice and the influence of related experiments on determined mechanical properties. Furthermore, existing scaling approaches are discussed in context of recent research findings.
Theoretical Model to Determine Effect of Ingress on Turbine Disks
Authors: Isobel Mear L. , Michael Owen J. , Lock Gary D.
Published: August 2015

Sealing air is used in gas turbines to reduce the amount of hot gas that is ingested through the rim seals into the wheel-space between the turbine disk and its adjacent stationary casing. The sealing air attaches itself to the rotor, creating a buffering effect that reduces the amount of ingested fluid that can reach the surface of the rotor. In this paper, a theoretical model is developed, and this shows that the maximum buffering effect occurs at a critical flow rate of sealing air, the value of which depends on the seal geometry. The model, which requires two empirical constants, is validated using experimental data, obtained from infrared (IR) temperature measurements, which are presented in a separate paper. There is good agreement between the adiabatic effectiveness of the rotor estimated from the model and that obtained from the IR measurements. Of particular interest to designers is that significant ingress can enter the wheel-space before its effect is sensed by the rotor.
First and Second Law Analysis of Intercooled Turbofan Engine
Authors: Zhao Xin , Thulin Oskar , Grönstedt Tomas
Published: August 2015

Although the benefits of intercooling for aero-engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero-engine intercooling, detailed performance data on optimized intercooled (IC) turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e., quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal IC geared turbofan engines for a long range mission are established with computational fluid dynamics (CFD) based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal IC geared turbofan engine provides a 4.5% fuel burn benefit over a non-IC geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor (HPC). The axial–radial high pressure ratio (PR) configuration allows for an ultrahigh overall PR (OPR). With an optimal top-of-climb (TOC) OPR of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultrahigh OPR axial–radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different OPRs. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal PR split exponent stays relatively independent of the overall engine PR.
Performance and Emission Investigations of Jatropha and Karanja Biodiesels in a Single-Cylinder Compression-Ignition Engine Using Endoscopic Imaging
Authors: Mistri Gayatri K. , Aggarwal Suresh K. , Longman Douglas , Agarwal Avinash K.
Published: August 2015

Biofuels produced from nonedible sources that are cultivated on marginal lands represent a viable source of renewable and carbon-neutral energy. In this context, biodiesel obtained from Jatropha and Karanja oil seeds have received significant interest, especially in South Asian subcontinent. Both of these fuels are produced from nonedible plant seeds with high oil content, which can be grown on marginal lands. In this research, we have investigated the performance and emission characteristics of Jatropha and Karanja methyl esters (biodiesel) and their blends with diesel. Another objective is to examine the effect of long-term storage on biodiesel's oxidative stability. The biodiesels were produced at Indian Institute of Technology Kanpur, (IIT Kanpur), India, and the engine experiments were performed in a single cylinder, four-stroke, compression ignition engine at Argonne National Laboratory (ANL), Chicago. An endoscope was used to visualize in-cylinder combustion events and examine the soot distribution. The effects of fuel and start of injection (SOI) on engine performance and emissions were investigated. Results indicated that ignition delay was shorter with biodiesel. Consequently, the cylinder pressure and premixed heat release were higher for diesel compared to biodiesel. Engine performance data for biodiesel (J100, K100) and biodiesel blends (J30, K30) showed an increase in brake thermal efficiency (BTE) (10.9%, 7.6% for biodiesel and blend, respectively), brake specific fuel consumption (BSFC) (13.1% and 5.6%), and nitrogen oxides (NOx) emission (9.8% and 12.9%), and a reduction in brake specific hydrocarbon emission (BSHC) (8.64% and 12.9%), and brake specific CO emission (BSCO) (15.56% and 4.0%). The soot analysis from optical images qualitatively showed that biodiesel and blends produced less soot compared to diesel. The temperature profiles obtained from optical imaging further supported higher NOx in biodiesels and their blends compared to diesel. Additionally, the data indicated that retarding the injection timing leads to higher BSFC, but lower flame temperatures and NOx levels along with higher soot formation for all test fuels. The physicochemical properties such as fatty acid profile, cetane number, and oxygen content in biodiesels support the observed combustion and emission characteristics of the fuels tested in this study. Finally, the effect of long-term storage is found to increase the glycerol content, acid value, and cetane number of the two biodiesels, indicating some oxidation of unsaturated fatty acids in the fuels.
Methodology to Correct the Magnetic Field Effect on Thin Film Measurements
Authors: Cuadrado D. G. , Lavagnoli S. , Paniagua G.
Published: August 2015

Machined ferrous metal components may carry a magnetic field, which in rotation disturb the output of electrical sensors. To minimize the effect on the electrical instrumentation, the rotating components are usually demagnetized. However, even after the demagnetization process, a residual magnetism unavoidably remains. This paper presents a methodology to predict the effects of a rotating magnetic field induced on thin film measurements. In addition to the prediction of the magnetic effects, a procedure to correct the spurious variation in the readings of thin film gauges has been developed to enhance the fidelity of the measurements. An analytical model was developed to reproduce the bias on the electrical signal from sensors exposed to rotor airfoils with magnets. The model is based on the Biot–Savart law to generate the magnetic field, and the Faraday's law to calculate the electromotive force induced along the measurement circuit. The model was assessed by means of controlled experiments varying the rotor tip clearance and rotational speed. The presented methodologies allowed the correction of the magnetic field effects. The raw signal of the thin film sensors, in the absence of any correction, is prone to deliver errors in the heat flux amounting to about 8% of the mean overall value. Thanks to the developed corrective approach, the residual magnetic effect contribution to the heat flux error would be 2% at most.
Application of a Creep-Damage Constitutive Model for the Rotor of a 1000 MW Ultrasupercritical Steam Turbine
Authors: Jiang Jishen , Wang Weizhe , Zhao Nailong , Wang Peng , Liu Yingzheng , Jiang Puning
Published: August 2015

A damage-based creep constitutive model for a wide stress range is applied to the creep analysis of a 1000 MW ultrasupercritical steam turbine, the inlet steam of which reaches 600 °C and 35 MPa. In this model, the effect of complex multiaxial stress and the nonlinear evolution of damage are considered. To this end, the model was implemented into the commercial software abaqus using a user-defined material subroutine code. The temperature-dependent material constants were identified from the experimental data of advanced heat resistant steels using curve fitting approaches. A comparison of the simulated and the measured results showed that they reached an acceptable agreement. The results of the creep analysis illustrated that the proposed approach explains the basic features of stress redistribution and the damage evolution in the steam turbine rotor over a wide range of stresses and temperatures.
Effect of micropatterned TiO2 nanotubes thin film on the deposition of endothelial extracellular matrix: For the purpose of enhancing surface biocompatibility
Authors: Wu Juejue , Li Jingan , Wu Feng , He Zikun , Yang Ping , Huang Nan
Published: August 2015

The vascular endothelial cells (EC) extracellular matrix (ECM) on the biomaterial surface can significantly improve the blood compatibility and cell compatibility of the cardiovascular materials. In the present study, two types of micropatterned TiO2 nanotubes surfaces (gronano and toponano) were fabricated on the titanium surface by photolithography and two-step anodizing technology, for the purpose of enhancing the deposition and loading ability of the EC ECM. The effect of the micropatterned nanotubes on EC ECM deposition and loading was investigated by qualitative and quantitative characterizations of type IV collagen (CoIV). The blood compatibility of the deposited ECM layers was evaluated by platelet adhesion and activation tests, and the endothelialization function of the deposited ECM layers was investigated by EC culture for 3 days. As a result, there was more CoIV on the toponano surface compared with the control. Meanwhile, the ECM loaded toponano (ECM/toponano) possessed better blood compatibility and better endothelialization than the control. This ECM loaded micro-/nanocomposite thin film was anticipated for the potential application of the surface modification of cardiovascular devices based on its excellent biocompatibility.
High active nitrogen flux growth of GaN by plasma assisted molecular beam epitaxy
Authors: McSkimming Brian M. , Chaix Catherine , Speck James S.
Published: August 2015

In the present study, the authors report on a modified Riber radio frequency (RF) nitrogen plasma source that provides active nitrogen fluxes more than 30 times higher than those commonly used for plasma assisted molecular beam epitaxy (PAMBE) growth of gallium nitride (GaN) and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N2 gas flow rates between 5 and 25 sccm while varying the plasma source's RF forward power from 200 to 600 W. The highest growth rate, and therefore the highest active nitrogen flux, achieved was ∼7.6 μm/h. For optimized growth conditions, the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 × 3 μm) on the order of 1 nm. Secondary ion mass spectroscopy impurity analysis demonstrates oxygen and hydrogen incorporation of 1 × 1016 and ∼5 × 1017, respectively. In addition, the authors have achieved PAMBE growth of GaN at a substrate temperature more than 150 °C greater than our standard Ga rich GaN growth regime and ∼100 °C greater than any previously reported PAMBE growth of GaN. This growth temperature corresponds to GaN decomposition in vacuum of more than 20 nm/min; a regime previously unattainable with conventional nitrogen plasma sources. Arrhenius analysis of the decomposition rate shows that samples with a flux ratio below stoichiometry have an activation energy greater than decomposition of GaN in vacuum while samples grown at or above stoichiometry have decreased activation energy. The activation energy of decomposition for GaN in vacuum was previously determined to be ∼3.1 eV. For a Ga/N flux ratio of ∼1.5, this activation energy was found to be ∼2.8 eV, while for a Ga/N flux ratio of ∼0.5, it was found to be ∼7.9 eV.
Formation of nanometer-thick delaminated amorphous carbon layer by two-step plasma processing of methacrylate-based polymer
Authors: Metzler Dominik , Weilnboeck Florian , Hernández Sandra C. , Walton Scott G. , Bruce Robert L. , Engelmann Sebastian , Salamanca-Riba Lourdes , Oehrlein Gottlieb S.
Published: August 2015

The authors show that extended He plasma pretreatment (PPT) of methacrylate-based 193 nm photoresist (PR) material in conjunction with a subsequent biased Ar plasma treatment can lead to blister formation at the polymer surface due to delamination of an ultrathin, ion-induced, dense, amorphous carbon (DAC) layer formed by low energy ion bombardment. For our experimental conditions, the delaminated layer is 1–2 nm thick and primarily composed of sp2-hybrized amorphous carbon. A He or Ar plasma process alone will not lead to this phenomenon, and so far the authors have only observed it for a methacrylate polymer. A possible mechanism of the formation of the ultrathin layer that is consistent with all observations is as follows: During He plasma pretreatment, volatile species are produced by ultraviolet/vacuum ultraviolet radiation-induced photolysis of the polymer pendant groups, e.g., adamantyl and chain-scissioning of the polymer backbone to a depth of greater than 100 nm. While volatile products formed close to the polymer surface can diffuse out during He PPT, those formed deep within the polymer bulk cannot and their concentration will become significant for extended He PPT. During the biased Ar plasma treatment step, a DAC surface layer is generated by Ar+ ion bombardment within the first seconds of plasma exposure. The thickness is dependent on ion energy and in the range of one to several nanometers. This layer appears to be impermeable to gaseous products formed in the PR material. Thus, volatile species diffusing to the surface can accumulate underneath the DAC layer, causing a loss of adhesion and subsequent delamination of this layer from the PR bulk film. The authors also report surface and electrical characterizations of the ultrathin DAC layer using optical microscopy, transmission electron microscopy, Raman and x-ray photoemission spectroscopy, and two-point probe techniques.
Repairing nanoscale devices using electron-beam-induced deposition of platinum
Authors: Peeters Lucas , Keller Andrew J. , Umansky Vladimir , Mahalu Diana , Goldhaber-Gordon David
Published: August 2015

Nanoscale device fabrication has enabled remarkable scientific advances. Yet a single broken electrode can render a complex device useless. The authors consider local electron-beam-induced deposition (EBID) of platinum as a method for restoring function to devices with damaged gate electrodes. The authors find that platinum deposits written with EBID at low acceleration voltage (350 V) remain conductive down to millikelvin temperatures, if they are annealed after deposition in the presence of oxygen. The authors apply this technique to a complex quantum dot device based on a GaAs/AlGaAs heterostructure.
Direct numerical simulation of fluid–acoustic interactions in a recorder with tone holes
Authors: Yokoyama Hiroshi , Miki Akira , Onitsuka Hirofumi , Iida Akiyoshi
Published: August 2015

To clarify fluid–acoustic interactions in an actual recorder with opened and closed tone holes, flow and acoustic fields were directly numerically simulated on the basis of the compressible Navier–Stokes equations. To validate the simulation accuracy, the flow field around the windway and sound pressure above the window were measured. The predicted acoustic fields clarify changes of the positions of pressure nodes and anti-nodes in accordance with the state of the tone holes and the Mach number of the jet velocity. The fundamental mechanism of the self-sustained oscillations in a three-dimensional actual recorder is visualized by the predicted acoustic and flow fields. This result is also consistent with the relationship between the jet behaviors and pressure fluctuations based on the jet-drive model. Moreover, the effects of the fine vortices in the jet, which appear at the high Mach number of jet velocity of 0.099, on the sound are discussed. The time difference between the generation of the disturbances and the most intense deflection of the jet is identified and compared with the time delay of acoustic reflection around the window.
An analytical model for the underwater sound pressure waveforms radiated when an offshore pile is driven
Authors: Hall Marshall V.
Published: August 2015

An analytical model has been developed for the pile vibration and consequent sound pressure and particle velocity radiated underwater when an offshore cylindrical pile is struck by a drop hammer. The model, which is based on the coupled equations of motion for axial and radial vibration of a thin cylindrical shell, yields frequency-dependent phase velocity and attenuation of these vibrations. The amplitude of the pulse of axial and radial displacement that travels down a pile following an axial impact is described in terms of the hammer properties. Solutions are obtained for the radiated sound pressure and particle velocity, using Junger and Feit's Transform Formulation of the Pressure Field of Cylindrical Radiators [(Acoustical Society of America, New York, 1993), p. 216]. The model is applied to published data on radiated noise from offshore driving of a steel pile. The modeled pressure waveforms at 12-m horizontal range and at 9 hydrophone depths correlate significantly with the measured waveforms. The modeled pressures of the initial positive peaks (appropriately low-pass filtered) agree with data to within 1 dB. The initial negative peaks however exceed the data by up to 7 dB, and as hydrophone depth increases, the model negative peaks have a maximum at 7 m, whereas the data have a maximum at 9 m.
Athletic Women’s Experiences of Amenorrhea: Biomedical Technologies, Somatic Ethics and Embodied Subjectivities
Authors: Thorpe Holly
Published: August 2015

Taking inspiration from Nikolas Rose (2007a, 2007b) and feminist new materialists, this paper creates space for athletic women’s voices of their biological and social bodies, and particularly their interactions with the medical professions and biomedical technologies. Drawing upon interviews with 10 female athletes and recreational exercisers who have experienced amenorrhea as a result of their exercise and dieting practices, it reveals how these women, as ‘somatic subjects’, are “reformulating their own answers to Kant’s three famous questions—what can I know? What must I do? What may I hope?—in the age of the molecular biopolitics of life itself” (Rose 2007a, p. 257). In so doing, we see that not all women are docile bodies within such operations of medical power and knowledge, and the “somatic ethics” being practiced by athletic women diagnosed with amenorrhea vary considerably, ranging from rejection and resistance to acceptance of medical advice. Ultimately, this paper challenges scholars of the moving body to consider what the ‘biological turn in social theory’ might mean for our field, and our understandings of moving bodies beyond the biology/culture dualism.
Strike a Pose! The Femininity Effect in Collegiate Women’s Sport
Authors: Musto Michela , McGann P.J.
Published: August 2015

The apologetic strategies women employ to manage the cultural tension between athleticism and hegemonic femininity are well documented. Existing research, however, tends to be small-scale. The cumulative symbolic implications of female athlete appearance on cultural ideals remain under-theorized as a result. Our quantitative content analysis of a stratified, random sample of 4,799 collegiate women athletes’ roster photos examined whether sport, school type, and geographical location are related to gendered appearance. Despite important contextual variation, we found overwhelming homogeneity across settings. Our results suggest that the normalization of women’s athleticism is limited and depends on subordinated femininities. Thus, despite some positive changes, team sport still helps stabilize and naturalize the gender order.
Leptospira interrogans lpxD
Homologue Is Required for Thermal Acclimatization and Virulence
Authors: Eshghi Azad , Henderson Jeremy , Trent M. Stephen , Picardeau Mathieu
Published: August 2015

Leptospirosis is an emerging disease with an annual occurrence of over 1 million human cases worldwide. Pathogenic
Leptospira
bacteria are maintained in zoonotic cycles involving a diverse array of mammals, with the capacity to survive outside the host in aquatic environments. Survival in the diverse environments encountered by
Leptospira
likely requires various adaptive mechanisms. Little is known about
Leptospira
outer membrane modification systems, which may contribute to the capacity of these bacteria to successfully inhabit and colonize diverse environments and animal hosts.
Leptospira
bacteria carry two genes annotated as UDP-3-
O
-[3-hydroxymyristoyl] glucosamine
N
-acyltransferase genes (la0512 and la4326 [
lpxD1
and
lpxD2
]) that in other bacteria are involved in the early steps of biosynthesis of lipid A, the membrane lipid anchor of lipopolysaccharide. Inactivation of only one of these genes, la0512/
lpxD1
, imparted sensitivity to the host physiological temperature (37°C) and rendered the bacteria avirulent in an animal infection model. Polymyxin B sensitivity assays revealed compromised outer membrane integrity in the
lpxD1
mutant at host physiological temperature, but structural analysis of lipid A in the mutant revealed only minor changes in the lipid A moiety compared to that found in the wild-type strain. In accordance with this, an
in trans
complementation restored the phenotypes to a level comparable to that of the wild-type strain. These results suggest that the gene annotated as
lpxD1
in
Leptospira interrogans
plays an important role in temperature adaptation and virulence in the animal infection model.
Preventing penetrating hand injuries in sabre fencing: an application and critique of the van Mechelen model by the Fédération Internationale d'Escrime
Authors: Harmer Peter A
Published: August 2015

Background/aim

To address the unusual phenomenon of unbroken blades causing penetrating hand injuries in sabre fencing by applying the van Mechelen model of the ‘sequence of prevention’.

Methods

Cases were collected from three surveillance systems and snowball sampling, and examined for potential aetiological factors. Presumed contributing factors were evaluated against the available evidence to compile a viable list for change. Determining a prevention strategy was guided by the philosophy of developing an approach that was most likely to produce a meaningful reduction in these injuries with the least disruption to the current norms of competitive sabre fencing.

Results

Nine factors which contributed, either individually or in some combination, to these injuries were grouped under three headings relating to: (1) the nature of modern sabre fencing, (2) the design of the sabre blade and (3) the vulnerability of the hand. Changes to the design and integrity of sabre gloves were selected as the most feasible option and new standards were introduced as compulsory in international competitions from 1 April 2014. The effect of this change is now being monitored via available surveillance systems.

Conclusions

The van Mechelen model is a useful framework for sports federations to apply to reduce injury risk, even for rare injuries. However, this research model has limitations in guiding the realities of sometimes competing interests among the scientific, political, financial and technical aspects of injury prevention interventions.
Effect of 1-h moderate-intensity aerobic exercise on intramyocellular lipids in obese men before and after a lifestyle intervention
Authors: Ipavec-Levasseur Stephanie , Croci Ilaria , Choquette Stéphane , Byrne Nuala M. , Cowin Gary , O’Moore-Sullivan Trisha M. , Prins Johannes B. , Hickman Ingrid J.
Published: August 2015

Intramyocellular lipids (IMCL) are depleted in response to an acute bout of exercise in lean endurance-trained individuals; however, it is unclear whether changes in IMCL content are also seen in response to acute and chronic exercise in obese individuals. We used magnetic resonance spectroscopy in 18 obese men and 5 normal-weight controls to assess IMCL content before and after an hour of cycling at the intensity corresponding with each participant’s maximal whole-body rate of fat oxidation (Fatmax). Fatmax was determined via indirect calorimetry during a graded exercise test on a cycle ergometer. The same outcome measures were reassessed in the obese group after a 16-week lifestyle intervention comprising dietary calorie restriction and exercise training. At baseline, IMCL content decreased in response to 1 h of cycling at Fatmax in controls (2.8 ± 0.4 to 2.0 ± 0.3 A.U., –39%, p = 0.02), but not in obese (5.4 ± 2.1 vs. 5.2 ± 2.2 A.U., p = 0.42). The lifestyle intervention lead to weight loss (–10.0 ± 5.4 kg, p < 0.001), improvements in maximal aerobic power (+5.2 ± 3.4 mL/(kg·min)), maximal fat oxidation rate (+0.19 ± 0.22 g/min), and a 29% decrease in homeostasis model assessment score (all p < 0.05). However, when the 1 h of cycling at Fatmax was repeated after the lifestyle intervention, there remained no observable change in IMCL (4.6 ± 1.8 vs. 4.6 ± 1.9 A.U., p = 0.92). In summary, there was no IMCL depletion in response to 1 h of cycling at moderate intensity either before or after the lifestyle intervention in obese men. An effective lifestyle intervention including moderate-intensity exercise training did not impact rate of utilisation of IMCL during acute exercise in obese men.
Analytical model for assessing collapse risk during mountain tunnel construction
Authors: Zhang Guo-Hua , Jiao Yu-Yong , Chen Li-Biao , Wang Hao , Li Shu-Cai
Published: August 2015

Risk management for safety in mountain tunnel construction is of great significance. However, existing research lags behind engineering applications. In this paper, the risk of mountain tunnel collapse is used as an example to illustrate a new assessment method based on case-based reasoning, advanced geological prediction, and rough set theory. First, the risk surroundings and risk factors involved in tunnel collapse are integrated and summarized, and a risk assessment index system is established for tunnel collapse. At the same time, because the dynamic response parameters obtained by the advanced geological prediction usually indicate a typical geological structure, sensitive response parameters are introduced in the assessment index system. Advanced risk assessment can be performed for tunnel sections at a certain distance ahead of the tunnel face. Second, the major risk surroundings and the advanced geological prediction results are analyzed for the tunnel under assessment. Cases with similar attribute characteristics are selected via comparison with previous cases. Attribute reduction and calculation of weights are subsequently performed for the risk surroundings and risk factors of similar cases based on the attribute significance theory of rough sets. Finally, index screening and objective weights are applied in the fuzzy comprehensive assessment model. The results of this paper can be used to improve the theoretical level and reliability of risk assessment in tunnel safety and serve as a reference for tunnel construction.
Long-term stability in modelled zooplankton influx could uphold major fish spawning grounds on the Norwegian continental shelf
Authors: Opdal Anders Frugård , Vikebø Frode B.
Published: August 2015

Early life stages of fish spawned on the Norwegian continental shelf have long been suggested to depend on eggs and nauplii from the crustacean zooplankton Calanus finmarchicus for survival. Calanus finmarchicus overwinters in the deep basins of the Norwegian Sea, and gravid females must be advected onto the shelf prior to spawning if eggs and nauplii larvae are to serve as food for fish larvae. In this study, cross-shelf advection of C. finmarchicus is simulated over 52 years (1960–2011) using a numerical ocean model coupled with an individual-based model. The results suggest that cross-shelf transport of C. finmarchicus is surprisingly stable across years and that transport is particularly concentrated immediately upstream of the two major spawning areas for the Northeast Arctic cod (Gadus morhua) and the Norwegian spring-spawning herring (Clupea harengus), namely Lofoten and Møre, respectively. Two large topographical features, the Træna Trough and the Norwegian Trench, appear to be funnelling C. finmarchicus onto the shelf in these two areas. This could suggest that the fish spawning grounds outside Møre and Lofoten are, in part, maintained owing to stable interannual food supply in spring.