bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Integration and Suicide‐Related Ideation from a Social Network Perspective: A Longitudinal Study among Inner‐City African Americans
Authors: Janet Kuramoto S. , Wilcox Holly C. , Latkin Carl A.
Published: March 2013

Social network density, as measured by the extent to which network members know each other, was examined to determine whether it is associated with suicide‐related ideation and plan approximately 3 years later. Eight hundred and nineteen African Americans were interviewed at Wave 1 (1997–1999) and Wave 4 (2001–2003) of the Self‐Help In Eliminating Life‐Threatening Diseases (SHIELD) study, a HIV preventive intervention study in Baltimore, MD. Multinomial logistic regression models were used to compare risks of suicide‐related ideation and plan at Wave 4 by Wave 1 density. Even after adjusting for baseline sociodemographic characteristics and depressive symptoms, individuals with a lower level of density were three times more likely to report suicide‐related ideation and plan in the past year at Wave 4. The findings reinforce the importance of social integration among inner‐city African Americans from a social network perspective. Future research should examine the mechanisms associated with this relationship and other social network constructs.
Patient Suicide: The Experience of Flemish Psychiatrists
Authors: Rothes Inês Areal , Scheerder Gert , Van Audenhove Chantal , Henriques Margarida Rangel
Published: March 2013

The experience of the most distressing patient suicide on Flemish psychiatrists is described. Of 584 psychiatrists, 107 filled a self‐report questionnaire. Ninety‐eight psychiatrists had been confronted with at least one patient suicide. Emotional suffering and impotence were the most common feelings reported. Changes in professional practice were described and included a more structured approach to the management of suicidal patients. Colleagues and contact with the patient's family were the most frequently used sources of help, whereas team case review and colleagues were rated as the most useful ones. Patient suicide leads to emotional suffering and has a considerable professional impact.
Transepidermal water loss in erythrodermic patients of various aetiologies
Authors: Mohd Noor Noorlaily , Hussein Suraiya H.
Published: March 2013

Background/purpose

Despite its severity not much work has been done to explore the barrier function in patients with erythroderma. This study compares TEWL between skin of healthy subjects and erythrodermic patients of various aetiologies and at different sites. We also assess TEWL between patients with acute and chronic erythroderma.

Methods

Twenty‐five erythrodermic patients and 26 age, race and sex‐matched healthy controls were recruited. TEWL measurements were performed at five sites; right cheek, left volar forearm, abdomen, upper back and right calf using Tewameter TM 210.

Results

TEWL in erythrodermic patients were significantly higher than healthy individuals at all the sites (P < 0.001). There were significant differences in TEWL between different anatomical sites in controls (P < 0.001) but not in patients. The highest TEWL for the patient and control groups were that of the abdomen and the right cheek respectively. Acute erythrodermic patients (n = 9) seemed to have a higher TEWL than chronic erythrodermic patients (n = 16) although the differences were not statistically significant. There was no significant difference in TEWL among erythrodermic patients of various aetiologies.

Conclusion

Erythrodermic skin regardless of aetiology has much higher TEWL compared to normal skin. Differences in TEWL among various anatomical sites observed in normal skin were not seen in erythroderma.
Preemptive treatment with voriconazole in lung transplant recipients
Authors: Neoh C.F. , Snell G.I. , Levvey B. , Kotsimbos T. , Morrissey C.O. , Slavin M.A. , Stewart K. , Kong D.C.M.
Published: March 2013

Background

Invasive fungal infection (IFI) is associated with high mortality in lung transplant (LTx) recipients. Data for voriconazole use in preemptive treatment remain scant.

Method

A single‐center, retrospective cohort study was conducted to investigate the efficacy and safety of voriconazole preemptive treatment for post‐LTx colonization.

Results

We reviewed 62 adult LTx patients, who received their first course of voriconazole prophylaxis (i.e., as preemptive treatment) between July 2003 and June 2010. Outcomes were determined at 6 and 12 months after commencing therapy. Aspergillus fumigatus (75.8%) was the most common colonizing isolate. Median duration of voriconazole prophylaxis was 85 days. At 6 months, 1 LTx patient (1.6%) had IFI, 47 (75.8%) cleared their colonizing isolate, 3 (4.8%) had persistent colonization, 7 (11.3%) had recurrent colonization, 1 (1.6%) had new colonization, 2 (3.2%) had aspergilloma, and 1 (1.6%) was clinically unstable with no culture results. Sixteen (25.8%) had died by 12 months. Ten (16.1%) had likely drug‐related hepatotoxicity. LTx patients with diabetes mellitus within 30 days before commencing prophylaxis were at higher risk of recurrent Aspergillus colonization at 6 months (P = 0.030). Chronic rejection within 30 days before prophylaxis was associated with 12‐month mortality (P = 0.007).

Conclusions

Voriconazole preemptive treatment resulted in low incidence of IFI and IFI‐related mortality.
Intramuscular glargine with or without concurrent subcutaneous administration for treatment of feline diabetic ketoacidosis
Authors: Marshall Rhett D. , Rand Jacquie S. , Gunew Marcus N. , Menrath Victor H.
Published: March 2013

Objective

To describe treatment response and outcome in 15 cats with diabetic ketoacidosis (DKA) initially stabilized with glargine administered intramuscularly (IM) with or without subcutaneous (SC) glargine.

Materials and Methods

Fifteen cats diagnosed with DKA were initially administered IM glargine (1–2 U) and in most cats (12/15 cats) this was combined with SC glargine (1–3 U). This was followed by intermittent IM glargine as required at intervals of 2 or more hours (range 2–22 h) and SC glargine (1–2 U) every 12 hours.

Key Findings

All 15 cats survived and were discharged from hospital (median 4 d; range 2–5 d) and one‐third (5/15) of cats subsequently achieved remission (median time 20 d; range 15–29 d). Complications included hypokalemia and hypophosphatemia, which were likely the result of DKA therapy rather than glargine treatment specifically.

Significance

This study demonstrates that glargine administered IM is an effective treatment for DKA in cats, and may provide an alternative to regular insulin. The same vial used for initial treatment of DKA can then be used for subsequent management with SC glargine injections. Future prospective randomized controlled trials evaluating clinical outcomes in cats with DKA using different types and routes of administration of insulin are warranted. A prospective randomized controlled trial is required to compare outcomes for IM and IV administration of glargine and regular insulin in DKA cats with or without SC glargine.
Effect of a sustained reduction in plasma free fatty acid concentration on insulin signalling and inflammation in skeletal muscle from human subjects
Authors: Liang Hanyu , Tantiwong Puntip , Sriwijitkamol Apiradee , Shanmugasundaram Karthigayan , Mohan Sumathy , Espinoza Sara , DeFronzo Ralph A. , Dubé John J. , Musi Nicolas
Published: March 2013

Key points

Reducing free fatty acids in the circulation gives protection against muscle insulin resistance.

In the present study, we investigated the mechanism by which free fatty acid reduction improves muscle insulin sensitivity.

The antilipolytic drug acipimox reduced the plasma concentration of unsaturated and saturated fatty acids in insulin‐resistant (obese and type 2 diabetic) subjects.

The reduction in plasma free fatty acid concentration caused by acipimox led to an improvement in local inflammation and insulin signalling in skeletal muscle.

The improvements in local inflammation and insulin signalling were more pronounced in obese type 2 diabetic subjects than obese non‐diabetic individuals, suggesting that diabetic subjects are more susceptible to the toxic effect of circulating free fatty acids.

Abstract  Free fatty acids (FFAs) have been implicated in the pathogenesis of insulin resistance. Reducing plasma FFA concentration in obese and type 2 diabetic (T2DM) subjects improves insulin sensitivity. However, the molecular mechanism by which FFA reduction improves insulin sensitivity in human subjects is not fully understood. In the present study, we tested the hypothesis that pharmacological FFA reduction enhances insulin action by reducing local (muscle) inflammation, leading to improved insulin signalling. Insulin‐stimulated total glucose disposal (TGD), plasma FFA species, muscle insulin signalling, IκBα protein, c‐Jun phosphorylation, inflammatory gene (toll‐like receptor 4 and monocyte chemotactic protein 1) expression, and ceramide and diacylglycerol (DAG) content were measured in muscle from a group of obese and T2DM subjects before and after administration of the antilipolytic drug acipimox for 7 days, and the results were compared to lean individuals. We found that obese and T2DM subjects had elevated saturated and unsaturated FFAs in plasma, and acipimox reduced all FFA species. Acipimox‐induced reductions in plasma FFAs improved TGD and insulin signalling in obese and T2DM subjects. Acipimox increased IκBα protein (an indication of decreased IκB kinase–nuclear factor κB signalling) in both obese and T2DM subjects, but did not affect c‐Jun phosphorylation in any group. Acipimox also decreased inflammatory gene expression, although this reduction only occurred in T2DM subjects. Ceramide and DAG content did not change. To summarize, pharmacological FFA reduction improves insulin signalling in muscle from insulin‐resistant subjects. This beneficial effect on insulin action could be related to a decrease in local inflammation. Notably, the improvements in insulin action were more pronounced in T2DM, indicating that these subjects are more susceptible to the toxic effect of FFAs.
Transients in global Ca2+ concentration induced by electrical activity in a giant nerve terminal
Authors: Neher Erwin , Taschenberger Holger
Published: March 2013

Abstract  Giant nerve terminals offer a unique opportunity to learn about dynamic changes in intracellular global Ca2+ concentration ([Ca2+]i) because this quantity can be measured precisely with indicator dyes and the composition of the intra‐terminal ionic milieu can be controlled. We review here recent literature on [Ca2+]i signalling in the calyx of Held and discuss what these measurements can tell us about endogenous Ca2+ buffers and Ca2+ extrusion mechanisms. We conclude that in spite of the favourable experimental conditions, some unresolved questions still remain regarding absolute values for the Ca2+‐binding ratio, the affinity of the basic fixed buffer and the Ca2+ affinities of the major endogenous Ca2+ binding proteins. Uncertainties about some of these presynaptic properties, including the roles of Mg2+ and ATP (as a Mg2+ buffer), however, extend to the point that mechanisms controlling the decay of [Ca2+]i signals in unperturbed terminals may have to be reconsidered.
Role of microprojections in myoendothelial feedback – a theoretical study
Authors: Nagaraja Sridevi , Kapela Adam , Tran Cam H. , Welsh Donald G. , Tsoukias Nikolaos M.
Published: March 2013

Key points

Endothelial microprojections (MPs) are cellular extensions of endothelial cells (ECs) that may be involved in regulation of smooth muscle cell (SMC) constriction in blood vessels.

We developed computational models to investigate the role of MPs in generating EC feedback during SMC stimulation. The models account for the geometry of MPs and heterogeneous distribution of membrane channels and receptors in an EC.

Simulations show that SMC stimulation causes calcium release in and around EC MPs that activates hyperpolarizing currents in ECs and moderates SMC constriction.

The results help us better understand the mechanisms that regulate blood flow and pressure.

Abstract  We investigated the role of myoendothelial projections (MPs) in endothelial cell (EC) feedback response to smooth muscle cell (SMC) stimulation using mathematical modelling. A previously developed compartmental EC–SMC model is modified to include MPs as subcellular compartments in the EC. The model is further extended into a 2D continuum model using a finite element method (FEM) approach and electron microscopy images to account for MP geometry. The EC and SMC are coupled via non‐selective myoendothelial gap junctions (MEGJs) which are located on MPs and allow exchange of Ca2+, K+, Na+ and Cl− ions and inositol 1,4,5‐triphosphate (IP3). Models take into consideration recent evidence for co‐localization of intermediate‐conductance calcium‐activated potassium channels (IKCa) and IP3 receptors (IP3Rs) in the MPs. SMC stimulation causes an IP3‐mediated Ca2+ transient in the MPs with limited global spread in the bulk EC. A hyperpolarizing feedback generated by the localized IKCa channels is transmitted to the SMC via MEGJs. MEGJ resistance (Rgj) and the density of IKCa and IP3R in the projection influence the extent of EC response to SMC stimulation. The predicted Ca2+ transients depend also on the volume and geometry of the MP. We conclude that in the myoendothelial feedback response to SMC stimulation, MPs are required to amplify the SMC initiated signal. Simulations suggest that the signal is mediated by IP3 rather than Ca2+ diffusion and that a localized rather than a global EC Ca2+ mobilization is more likely following SMC stimulation.
Three-Dimensional Design and Optimization of a Transonic Rotor in Axial Flow Compressors
Authors: Okui Hidetaka , Verstraete Tom , Van den Braembussche R. A. , Alsalihi Zuheyr
Published: March 2013

This paper presents a 3-D optimization of a moderately loaded transonic compressor rotor by means of a multiobjective optimization system. The latter makes use of a differential evolutionary algorithm in combination with an Artificial Neural Network and a 3D Navier-Stokes solver. Operating it on a cluster of 30 processors enabled the evaluation of the off-design performance and the exploration of a large design space composed of the camber line and spanwise distribution of sweep and chord length. Objectives were an increase of efficiency at unchanged stall margin by controlling the shock waves and off-design performance curve. First designs of single blade rows allowed a better understanding of the impact of the different design parameters. Forward sweep with unchanged camber improved the peak efficiency by only 0.3% with the same stall margin. Backward sweep with an optimized S shaped camber line improved the efficiency by 0.6% at unchanged stall margin. It is explained how the camber line control can introduce the same effect as forward sweep and compensate the expected negative effects of backward sweep. The best results (0.7% increase in efficiency and unchanged stall margin) have been obtained by a stage optimization that allows also a spanwise redistribution of the rotor flow and an increase of loading by extra flow turning. The latter compensates the loading shift induced by the backward sweep in order to reduce the inlet Mach number at the downstream stator hub.
Analysis of the Unsteady Overtip Casing Heat Transfer in a High Speed Turbine
Authors: Lavagnoli S. , Paniagua G. , De Maesschalck C. , Yasa T.
Published: March 2013

In modern gas turbine engines, the rotor casing is vulnerable to thermal failures due to large unsteady heat fluxes. The rotor tip flow unsteadiness is induced by the periodic passage of the rotor blades, with an intensity dependent on the tip gap geometry. Hence, the understanding of the physics is of paramount importance to develop appropriate predictive tools and improve the cooling schemes. The present research aims at providing essential information on the flow conditions, which should serve to assess the relative impact of the overtip flow, tip gap magnitude, and work extraction processes on the casing thermal load. This paper presents simultaneous measurements of steady and unsteady heat transfer, pressure and rotor tip clearance in the casing of a transonic turbine stage. The research article was tested in a compression tube facility operating at engine representative conditions (vane Mach number 1.07, vane outlet Reynolds number 1.3 × 106, pressure ratio is 2.92, at 6790 rpm). The rotor blade geometry has a flat tip with a nominal tip clearance of about 0.4% of blade height. The heat transfer, pressure, and tip clearance data were obtained at three circumferential positions around the turbine casing. The heat flux was monitored using a single-layered thin film gauge able to resolve with high fidelity the wall temperature fluctuations. The heat flux sensor was mounted on a probe equipped with a heating device that allows varying the wall temperature. A series of experiments was performed at different heating rates to derive the local adiabatic wall temperature and the adiabatic convective heat transfer coefficient. A high bandwidth capacitive sensor provided the instantaneous value of the single blade tip clearance. A simple zero-dimensional model has been proved effective to predict the local flow temperature while the rotor spins up prior to the test, and estimate the overtip flow temperature during a test.
Impact of the Flow on an Acoustic Excitation System for Aeroelastic Studies
Authors: Freund Oliver , Bartelt Michael , Mittelbach Marc , Montgomery Matthew , Vogt Damian M. , Seume Joerg R.
Published: March 2013

The flow in turbomachines is highly unsteady. Effects like vortices, flow separation, and shocks are an inevitable part of the turbomachinery flow. Furthermore, high blade aspect ratios, aerodynamically highly loaded and thin profiles increase the blade sensitivity to vibrations. According to the importance of aeroelasticity in turbomachines, new strategies for experimental studies in rotating machines must be developed. A basic requirement for aeroelastic research in rotating machines is to be able to excite the rotor blades in a defined manner. Approaches for active blade excitation in running machines may be piezoelectric elements, magnetism, or acoustics. Contact-free excitation methods are preferred, since additional mistuning is brought into the investigated system otherwise. A very promising method for aeroelastic research is the noncontact acoustic excitation method. In this paper, investigations on the influence of an annular cascade flow on the blade vibration, excited by an acoustic excitation system, are presented for the first time. These investigations are carried out at the Aeroelastic Test Rig of the Royal Institute of Technology in Stockholm. By varying the excitation angle, the outlet Mach number, and the relative position of the excited blade to the excitation system, the influence of the flow on the acoustic excitation is quantified. The results show that there is a strong dependency of the excited vibration amplitude on the excitation angle if the outlet Mach number is increased, which implies that preferable excitation directions exist. Furthermore, it is shown that a benefit up to 23% in terms of excited vibration amplitude can be reached if the flow velocity is raised.
Forced Response Analyses of Mistuned Radial Inflow Turbines
Authors: Giersch Thomas , Hönisch Peter , Beirow Bernd , Kühhorn Arnold
Published: March 2013

Radial turbine wheels designed as blade integrated disks (blisk) are widely used in various industrial applications. However, related to the introduction of exhaust gas turbochargers in the field of small and medium sized engines, a sustainable demand for radial turbine wheels has come along. Despite those blisks being state of the art, a number of fundamental problems, mainly referring to fluid-structure-interaction and, therefore, to the vibration behavior, have been reported. Aiming to achieve an enhanced understanding of fluid-structure-interaction in radial turbine wheels, a numerical method, able to predict forced responses of mistuned blisks due to aerodynamic excitation, is presented. In a first step, the unsteady aerodynamic forcing is determined by modeling the spiral casing, the stator vanes, and the rotor blades of the entire turbine stage. In a second step, the aerodynamic damping induced by blade vibration is computed using a harmonic balance technique. The structure itself is represented by a reduced order model being extended by aerodynamic damping effects and aerodynamic forcings. Mistuning is introduced by adjusting the modal stiffness matrix based on results of blade by blade measurements that have been performed at rest. In order to verify the numerical method, the results are compared with strain-gauge data obtained during rig-tests. As a result, a measured low engine order excitation was found by modeling the spiral casing. Furthermore, a localization phenomenon due to frequency mistuning could be proven. The predicted amplitudes are close to the measured data.
Performance Improvement of a Return Channel in a Multistage Centrifugal Compressor Using Multiobjective Optimization
Authors: Nishida Yoshifumi , Kobayashi Hiromi , Nishida Hideo , Sugimura Kazuyuki
Published: March 2013

The effect of the design parameters of a return channel on the performance of a multistage centrifugal compressor was numerically investigated, and the shape of the return channel was optimized using a multiobjective optimization method based on a genetic algorithm to improve the performance of the centrifugal compressor. The results of sensitivity analysis using Latin hypercube sampling suggested that the inlet-to-outlet area ratio of the return vane affected the total pressure loss in the return channel, and that the inlet-to-outlet radius ratio of the return vane affected the outlet flow angle from the return vane. Moreover, this analysis suggested that the number of return vanes affected both the loss and the flow angle at the outlet. As a result of optimization, the number of return vane was increased from 14 to 22 and the area ratio was decreased from 0.71 to 0.66. The radius ratio was also decreased from 2.1 to 2.0. Performance tests on a centrifugal compressor with two return channels (the original design and optimized design) were carried out using two-stage test apparatus. The measured flow distribution exhibited a swirl flow in the center region and a reversed swirl flow near the hub and shroud sides. The exit flow of the optimized design was more uniform than that of the original design. For the optimized design, the overall two-stage efficiency and pressure coefficient were increased by 0.7% and 1.5%, respectively. Moreover, the second-stage efficiency and pressure coefficient were respectively increased by 1.0% and 3.2%. It is considered that the increase in the second-stage efficiency was caused by the increased uniformity of the flow, and the rise in the pressure coefficient was caused by a decrease in the residual swirl flow. It was thus concluded from the numerical and experimental results that the optimized return channel improved the performance of the multistage centrifugal compressor.
Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
Authors: Kunte Robert , Jeschke Peter , Smythe Caitlin
Published: March 2013

The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing system in a high pressure centrifugal compressor stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global stage performance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state-of-the-art centrifugal compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the downstream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An optimal relative circumferential position for the stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a centrifugal compressor stage, especially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental principles of flow phenomena in the diffusing system of a centrifugal compressor.
Experimental Study on Effects of Internal Ribs and Rear Bumps on Film Cooling Effectiveness
Authors: Sakai Eiji , Takahashi Toshihiko , Agata Yukiko
Published: March 2013

This paper reports the detailed measurement of the film cooling effectiveness for a scaled up film-cooling hole with an expanded exit fed by a smooth and ribbed secondary flow channel, which is an arrangement typical of turbine blades. The experiments are carried out at blowing ratios ranging from 0.4 to 1.25, and ten different rib patterns, including forward oriented ribs and inverse oriented ribs, are evaluated. Furthermore, in order to develop an efficient film-cooling technique, several kinds of bumps are installed downstream of the hole exits and the effects of the bumps on the film cooling effectiveness are investigated. The bump structures tested here are semicircular, hemispherical, and cylindrical bumps. The results show that the rib orientation strongly affects the film cooling effectiveness. When the blowing ratio is comparatively low, the forward oriented ribs afford a higher film cooling effectiveness. On the contrary, when the blowing ratio is comparatively high, the inverse oriented ribs afford a higher film cooling effectiveness. The cylindrical bump provides a better spreading of the ejected secondary flow than the other bumps, leading to a higher film cooling effectiveness. To clarify how the bumps improve the film cooling effectiveness, computational simulations are performed. The simulations indicate that a longitudinal vortex, formed at the trailing edge of the cylindrical bump, improves the film cooling effectiveness by generating downward velocity vectors.
Compressor Efficiency Variation With Rotor Tip Gap From Vanishing to Large Clearance
Authors: Sakulkaew S. , Tan C. S. , Donahoo E. , Cornelius C. , Montgomery M.
Published: March 2013

Compressor efficiency variation with rotor tip gap is assessed using numerical simulations on an embedded stage representative of that in a large industrial gas turbine with Reynolds number ∼ 2 × 106 to 7 × 106. The results reveal three distinct behaviors of efficiency variation with tip gap. For relatively small tip gap (less than 0.8% span), the change in efficiency with tip gap is nonmonotonic with an optimum tip gap for maximum efficiency. The optimum tip gap is set by two competing flow processes: decreasing tip leakage mixing loss and increasing viscous shear loss at the casing with decreasing tip gap. An optimum tip gap scaling is established and shown to satisfactorily quantify the optimal gap value. For medium tip gap (0.8%–3.4% span), the efficiency decreases approximately on a linear basis with increasing tip clearance. However, for tip gap beyond a threshold value (3.4% span for this rotor), the efficiency becomes less sensitive to tip gap as the blade tip becomes more aft-loaded thus reducing tip flow mixing loss in the rotor passage. The threshold value is set by the competing effects between increasing tip leakage flow and decreasing tip flow induced mixing loss with increasing tip gap. Thus, to desensitize compressor performance variation with blade gap, rotor should be tip aft-loaded and hub fore-loaded while stator should be tip fore-loaded and hub aft-loaded as much as feasible. This reduces the opportunity for clearance flow mixing loss and maximizes the benefits of reversible work from unsteady effects in attenuating the clearance flow through the downstream blade-row. The net effect can be an overall compressor performance enhancement in terms of efficiency, pressure rise capability, robustness to end gap variation, and potentially useful operable range broadening.
Bend Geometries in Internal Cooling Channels for Improved Thermal Performance
Authors: Saha Krishnendu , Acharya Sumanta
Published: March 2013

The pressure drop and heat transfer in a two pass internal cooling channel with two different bend geometries is experimentally studied with the goal of improving the thermal performance factor (TPF) in the coolant channel. The geometries studied are (1) a baseline U-bend geometry with a rectangular divider wall, (2) a symmetrical bulb at the end of the divider wall, and (3) a combination of the symmetrical bulb and a bow on the opposite outer wall leading to a shaped flow contraction and expansion in the bend. Tests are conducted for four Reynolds number ranging from 10,000 to 55,000. The symmetrical bulb eliminates the separation due to the sharp turn and makes the heat transfer distribution in the bend portion more uniform. This modification reduces the bend pressure drop by 37% and augments the TPF by nearly 29% compared to the baseline case. The combination of bulb and bow case increases the local heat transfer in the bend region significantly, and reduces the bend pressure drop by nearly 27% leading to an augmentation of the TPF of 32% compared to the baseline case. These improvements in TPF point to the benefits of using the improved bend designs in internal cooling channels.
Numerical Simulation of Formation and Distortion of Taylor Cones
Authors: Sarkar Kamal , Hoos Palmira , Urias Alberto
Published: March 2013

Taylor cones are integral parts in many important applications like electrospinning and electrospray mass spectroscopy. A better understanding of this complex phenomenon of Taylor cone is critical for better control of these processes. As an example, if it is possible to identify and prioritize the roles of fluid characteristics and externally applied electric field, it might be easier to target and control the diameters of nanofibers in an electrospinning process. Under the influence of high electric fields, Taylor cones are formed by a number of liquids including many polymeric solutions. Because of small spatial (microns and below) and temporal (microseconds and below) scales, it is difficult to experimentally study the transient formation of Taylor cones. A number of theoretical analyses have been done under simplifying assumptions like uniform electric field, constant electrohydrodynamic behaviors of the fluid, stationary droplet, etc. Initial Taylor formulation included the introduction of “leaky dielectric” that accumulated charges only on the surface for certain dielectric fluids. Yarin et al. later developed analysis for stationary droplets assuming them to be “perfectly conducting”. To simulate the electrospinning process, the formulation needs the ability to analyze moving boundary conditions, complex fluid properties, three dimensional geometry, and nonlinear coupling between air and liquid, among others. To overcome some of the assumptions of theoretical analyses and as another complementary tool, a computer simulation method was proposed using a commercially available software. In this investigation, much studied aqueous polyethylene oxide (PEO) solution was used to study formation and distortion of Taylor cones. An initial velocity was given to the fluid from the tip of a nozzle and an appropriate electric field was applied to form the Taylor cones. Literature values were used for flow, fluid, and electrical characteristics of the solution. By appropriately manipulating fluid velocities and electric fields, simulations were successful to both replicate the classical cone and distort it to various degrees. These formation and distortion of Taylor cones were similar to reported experimental results. While the numerical and experimental Taylor cones were significantly different in sizes, nondimensional shapes, and sizes of both the results were strikingly similar. Velocities of the fluid in the jet jumped almost 50 times to meters/second as was experimentally observed. Unlike theoretical solutions, the simulation results showed the interaction of the electric fields between the air and advancing fluid tip.
Focus Issue: From Genomic Mutations to Oncogenic Pathways
Authors: Gough Nancy R.
Published: March 2013

Understanding alterations in signaling networks is key to developing rational, personalized cancer therapies.
Staphylococcus aureus Extracellular Vesicles Carry Biologically Active β-Lactamase
Authors: Lee Jaewook , Lee Eun-Young , Kim Si-Hyun , Kim Dae-Kyum , Park Kyong-Su , Kim Kwang Pyo , Kim Yoon-Keun , Roh Tae-Young , Gho Yong Song
Published: March 2013

Gram-positive bacteria naturally produce extracellular vesicles. However, little is known regarding the functions of Gram-positive bacterial extracellular vesicles, especially in the bacterial community. Here, we investigated the role of
Staphylococcus aureus
extracellular vesicles in interbacterial communication to cope with antibiotic stress. We found that
S. aureus
liberated BlaZ, a β-lactamase protein, via extracellular vesicles. These extracellular vesicles enabled other ampicillin-susceptible Gram-negative and Gram-positive bacteria to survive in the presence of ampicillin. However,
S. aureus
extracellular vesicles did not mediate the survival of tetracycline-, chloramphenicol-, or kanamycin-susceptible bacteria. Moreover,
S. aureus
extracellular vesicles did not contain the
blaZ
gene. In addition, the heat-treated
S. aureus
extracellular vesicles did not mediate the survival of ampicillin-susceptible bacteria. The β-lactamase activities of
S. aureus
soluble and extracellular vesicle-associated BlaZ were similar, but only the extracellular vesicle-associated BlaZ was resistant to protease digestion, which suggests that the enzymatic activity of BlaZ in extracellular vesicles is largely protected by the vesicle structure. Our observations provide evidence of the important role of
S. aureus
extracellular vesicles in antibiotic resistance, which allows the polymicrobial community to continue to evolve and prosper against antibiotics.
Mitochondrial Dysfunction Is the Focus of Quaternary Ammonium Surfactant Toxicity to Mammalian Epithelial Cells
Authors: Inácio Ângela S. , Costa Gabriel N. , Domingues Neuza S. , Santos Maria S. , Moreno António J. M. , Vaz Winchil L. C. , Vieira Otília V.
Published: March 2013

Surfactants have long been known to have microbicidal action and have been extensively used as antiseptics and disinfectants for a variety of general hygiene and clinical purposes. Among surfactants, quaternary ammonium compounds (QAC) are known to be the most useful antiseptics and disinfectants. However, our previous toxicological studies showed that QAC are also the most toxic surfactants for mammalian cells. An understanding of the mechanisms that underlie QAC toxicity is a crucial first step in their rational use and in the design and development of more effective and safer molecules. We show that QAC-induced toxicity is mediated primarily through mitochondrial dysfunction in mammalian columnar epithelial cell cultures
in vitro
. Toxic effects begin at sublethal concentrations and are characterized by mitochondrial fragmentation accompanied by decreased cellular energy charge. At very low concentrations, several QAC act on mitochondrial bioenergetics through a common mechanism of action, primarily by inhibiting mitochondrial respiration initiated at complex I and, to a lesser extent, by slowing down coupled ADP phosphorylation. The result is a reduction of cellular energy charge which, when reduced below 50% of its original value, induces apoptosis. The lethal effects are shown to be primarily a result of this process. At higher doses (closer to the critical micellar concentration), QAC induce the complete breakdown of cellular energy charge and necrotic cell death.
Effect of H
2
Blockade and Food on Single-Dose Pharmacokinetics of GSK1322322, a Peptide Deformylase Inhibitor Antibacterial
Authors: Naderer Odin J. , Dumont Etienne , Zhu John , Kurtinecz Milena , Jones Lori S.
Published: March 2013

GSK1322322 is first in a new class of antibiotics, peptide deformylase inhibitors, and is active against multidrug-resistant respiratory and skin pathogens. Part 1 of this phase 1, randomized, single-dose (1,000 mg) study in 20 healthy volunteers compared the relative bioavailability of three different tablet formulations of GSK1322322 (fast release, intermediate release, and slow release) to that of the previously studied powder-in-bottle formulation to assess the optimal formulation for progression into clinical trials. Part 2 assessed the effect of a high-fat meal and drug interaction with an H
2
blocker and an H
2
blocker plus vitamin C on the pharmacokinetic profile of GSK1322322. Of the three tablet formulations, fast-release GSK1322322 provided pharmacokinetic profiles similar to those of the powder-in-bottle reference formulation (∼93% relative bioavailability) and was selected for progression in part 2. When GSK1322322 was administered with a high-fat meal, the maximum observed plasma concentration (
C
max
) was reduced by 20%, and the time to maximum plasma concentration (
T
max
) was delayed by 1.9 h. The exposure (area under the concentration-time curve [AUC]) increased by ∼20% compared to that in volunteers in the fasted state. Coadministration of GSK1322322 with an H
2
blocker resulted in a slight delay in absorption (
T
max
∼0.75 h later) and 58 and 38% decreases in the
C
max
and AUC
0–∞
values, respectively, compared to GSK1322322 alone. This effect was reversed with vitamin C intake (i.e., no delay in
T
max
and the
C
max
and AUC
0–∞
values decreased by only 21 and 12%, respectively). GSK1322322 was generally well tolerated, and most adverse events were mild in intensity during both parts of the study.
Flagellar Motility Is a Key Determinant of the Magnitude of the Inflammasome Response to Pseudomonas aeruginosa
Authors: Patankar Yash R. , Lovewell Rustin R. , Poynter Matthew E. , Jyot Jeevan , Kazmierczak Barbara I. , Berwin Brent
Published: March 2013

We previously demonstrated that bacterial flagellar motility is a fundamental mechanism by which host phagocytes bind and ingest bacteria. Correspondingly, loss of bacterial motility, consistently observed in clinical isolates from chronic
Pseudomonas aeruginosa
infections, enables bacteria to evade association and ingestion of
P. aeruginosa
by phagocytes both
in vitro
and
in vivo
. Since bacterial interactions with the phagocyte cell surface are required for type three secretion system-dependent NLRC4 inflammasome activation by
P. aeruginosa
, we hypothesized that reduced bacterial association with phagocytes due to loss of bacterial motility, independent of flagellar expression, will lead to reduced inflammasome activation. Here we report that inflammasome activation is reduced in response to nonmotile
P. aeruginosa
. Nonmotile
P. aeruginosa
elicits reduced IL-1β production as well as caspase-1 activation by peritoneal macrophages and bone marrow-derived dendritic cells
in vitro
. Importantly, nonmotile
P. aeruginosa
also elicits reduced IL-1β levels
in vivo
in comparison to those elicited by wild-type
P. aeruginosa
. This is the first demonstration that loss of bacterial motility results in reduced inflammasome activation and antibacterial IL-1β host response. These results provide a critical insight into how the innate immune system responds to bacterial motility and, correspondingly, how pathogens have evolved mechanisms to evade the innate immune system.
RegA, the Regulator of the Two-Component System RegB/RegA of Brucella suis, Is a Controller of Both Oxidative Respiration and Denitrification Required for Chronic Infection in Mice
Authors: Abdou Elias , Deredjian Amélie , Jiménez de Bagüés María Pilar , Köhler Stephan , Jubier-Maurin Véronique
Published: March 2013

Adaptation to oxygen deficiency is essential for virulence and persistence of
Brucella
inside the host. The flexibility of this bacterium with respect to oxygen depletion is remarkable, since
Brucella suis
can use an oxygen-dependent transcriptional regulator of the FnrN family, two high-oxygen-affinity terminal oxidases, and a complete denitrification pathway to resist various conditions of oxygen deficiency. Moreover, our previous results suggested that oxidative respiration and denitrification can be simultaneously used by
B. suis
under microaerobiosis. The requirement of a functional cytochrome
bd
ubiquinol oxidase for nitrite reductase expression evidenced the linkage of these two pathways, and the central role of the two-component system RegB/RegA in the coordinated control of both respiratory systems was demonstrated. We propose a scheme for global regulation of
B. suis
respiratory pathways by the transcriptional regulator RegA, which postulates a role for the cytochrome
bd
ubiquinol oxidase in redox signal transmission to the histidine sensor kinase RegB. More importantly, RegA was found to be essential for
B. suis
persistence
in vivo
within oxygen-limited target organs. It is conceivable that RegA acts as a controller of numerous systems involved in the establishment of the persistent state, characteristic of chronic infections by
Brucella
.
Granzyme D Is a Novel Murine Mast Cell Protease That Is Highly Induced by Multiple Pathways of Mast Cell Activation
Authors: Rönnberg Elin , Calounova Gabriela , Guss Bengt , Lundequist Anders , Pejler Gunnar
Published: March 2013

Granzymes are serine proteases known mostly for their role in the induction of apoptosis. Granzymes A and B have been extensively studied, but relatively little is known about granzymes C to G and K to M. T cells, lymphohematopoietic stromal cells, and granulated metrial gland cells express granzyme D, but the function of granzyme D is unknown. Here we show that granzyme D is expressed by murine mast cells and that its level of expression correlates positively with the extent of mast cell maturation. Coculture of mast cells with live, Gram-positive bacteria caused a profound, Toll-like receptor 2 (TLR2)-dependent induction of granzyme D expression. Granzyme D expression was also induced by isolated bacterial cell wall components, including lipopolysaccharide (LPS) and peptidoglycan, and by stem cell factor, IgE receptor cross-linking, and calcium ionophore stimulation. Granzyme D was released into the medium in response to mast cell activation. Granzyme D induction was dependent on protein kinase C and nuclear factor of activated T cells (NFAT). Together, these findings identify granzyme D as a novel murine mast cell protease and implicate granzyme D in settings where mast cells are activated, such as bacterial infection and allergy.
Melting down the Ice Queen: an integrative treatment of anorexia nervosa
Authors: Hartogs Bregje M A , Eikmans Kirsten M , Bartels-Velthuis Agna A
Published: March 2013

A 23-year-old woman with anorexia nervosa (AN) and a strong need for control was offered an integrative treatment, empowering the patient to be an active participant and advocating shared decision-making. To emphasise this, both the therapist and patient describe their views on the therapy. The integrative treatment resulted in more psychological flexibility and behavioural improvements, as is evident from an increased weight, a decreased dietary restriction and an increased valued action. The strength of this integrative treatment is based on accepting and encouraging patient's self-chosen treatment method, within healthy limits, and thereby creating a flexible, supportive and empowering therapeutic alliance. More research is needed to test the efficacy of combining complementary therapies within conventional treatments of AN.
An 8-year follow-up of a patient with acute myocardial infarction complicated with ventricular rupture and cerebral thrombosis treated conservatively: a cohort study
Authors: Li Xue , Zhao Lianyou , Zheng Qiangsun
Published: March 2013

Cardiac rupture is a complication of myocardial infarction (MI) with extremely high mortality. Poor prognosis is usually predicted in conservatively treated patients. The treatment for cardiac rupture and thrombosis is in conflict. We reported an MI case of cardiac rupture and cerebral thrombosis using a conservative method. This case indicated that (1) It is noteworthy that patients suffering from the subacute form of rupture may remain haemodynamically stable. This type of patients may benefit from a conservative treatment without anticoagulation or antiplatelet at the onset of cardiac rupture. (2) Thirty days following cardiac rupture, it is safe to use warfarin anticoagulation for cerebral thrombosis treatment. The patient suffered from acute MI, cardiac rupture and subsequently cerebral thrombosis. We treated this patient in a conservative manner and the patient remained alive for 8 years. This case suggested that it may be safe to use warfarin anticoagulation treatment for cerebral thrombosis 30 days following cardiac rupture.
Incidental pathologically proven pulmonary hamartoma in a patient with carcinoma tongue
Authors: Jindal Aditya , Madan Karan , Nijhawan Raje , Singh Navneet
Published: March 2013

Pulmonary hamartomas are usually clinically silent and found incidentally on chest radiographs. They can lead to diagnostic confusion especially in patients who have been previously treated for primary cancers at other sites. This can lead to consideration of metastatic malignancy as the primary diagnostic possibility. In this case, evaluation of a solitary pulmonary nodule (SPN) in a patient with carcinoma of tongue led to the diagnosis of pulmonary chondroid hamartoma. This highlights the fact that a pulmonary nodule in a patient with progressive cancer at another site does not always indicate pulmonary metastasis.
Prostate abscess: MRSA spreading its influence into Gram-negative territory: case report and literature review
Authors: Deshpande Aartee , Haleblian George , Rapose Alwyn
Published: March 2013

Prostate abscess is a rare complication of an ascending urinary tract infection (UTI). Its incidence has reduced secondary to routine and early use of antibiotics for treatment of UTIs. Prostate abscess has been reported in patients with uncontrolled diabetes, prolonged indwelling urinary catheters, prostate biopsy or other instrumentation of lower urinary tract. Prostate abscess is most commonly associated with Gram-negative bacteria.Staphylococcus aureusis rarely implicated and has been reported in patients with underlying risk factors like long-term or uncontrolled diabetes, intravenous drug abuse or bacteraemia. We present a rare case of prostate abscess due to methicillin resistantS aureuswithout obvious risk factors.
THE EFFECT OF ELECTRIC FIELD ON THE DIELECTRIC PERMITTIVITY OF BST/STO SUPERLATTICE
Authors: ZUO ZHI-GAO , LING FU-RI , LI DAN , LIU JIN-SONG , YAO JIAN-QUAN
Published: March 2013

A nonlinear thermodynamic model is developed for investigating the effect of external electric field on the dielectric properties of Ba 0.6 Sr 0.4 TiO 3/ SrTiO 3( BST / STO ) super-lattice. The transformation strain induced by the external electrical field are analyzed and calculated. It is found that the dielectric and ferroelectric properties of the ( BST / STO ) superlattice vary substantially with the interlayer elastic interaction caused by the external electrical field. The results also provide better understanding of the dielectric behavior of BST / STO superlattice with external electric field and a necessary step in the development of the general nonlinear theory.