bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of the Tip Clearance Flow for a High Reynolds Number Axial-Flow Rotor: Part 2 — Detailed Flow Measurements
Authors: Zierke W. C. , Farrell K. J. , Straka W. A.
Published: February 2015

A high Reynolds number pump (HIREP) facility has been used to acquire flow measurements in the rotor blade tip clearance region-with blade chord Reynolds numbers of 3,900,000 and 5,500,000. The initial experiment involved rotor blades with varying tip clearances, while a second experiment involved a more detailed investigation of a rotor blade row with a single tip clearance. This paper focuses on detailed flow measurements of the tip leakage vortex. These detailed measurements show the effects of tip clearance size and downstream distance on the structure of the rotor tip leakage vortex. The character of the velocity profile along the vortex core changes from a jet-like profile to a wake-like profile as the tip clearance becomes smaller. These vortex velocity profiles-as well as the levels of unsteadiness-dominate the rotor wake structure in the endwall region. Also, for small clearances, the presence and proximity of the casing endwall affects the roll-up, shape, dissipation, and unsteadiness of the tip leakage vortex. Measurements also show how much circulation is retained by the blade tip and how much is shed into the vortex-a vortex associated with high losses.
Experimental Investigation of the Flow Field in a Multistage Axial Flow Compressor
Authors: Lakshminarayana B. , Suryavamshl N. , Prato J. , Moritz R.
Published: February 2015

The nature of the flow field in a three stage axial flow compressor, including a detailed survey at the exit of an embedded stator as well as the overall performance of the compressor is presented and interpreted in this paper. The measurements include area traverse of a miniature five hole probe (1.07 mm dia) downstream of stator 2, radial traverses of a miniature five hole probe at the inlet, downstream of stator 3 and at the exit of the compressor at various circumferential locations, area traverse of a low response thermocouple probe downstream of stator 2, radial traverses of a single sensor hot-wire probe at the inlet, and casing static pressure measurements at various circumferential and axial locations across the compressor at the peak efficiency operating point. Spectral analysis of the hot-wire data reveal the existence of several harmonics of all three rotor blade passing frequencies at the inlet of the compressor. Mean velocity, pressure and total temperature contours as well as secondary flow contours at the exit of the stator 2 are reported and interpreted. Hub clearance flow is shown to eliminate the suction surface corner separation. Secondary flow contours show the migration of fluid particles toward the core of the low pressure regions located near the suction side casing endwall corner. The RMS value of the spatial fluctuations in mean velocity downstream of the second stator (which appear as temporal variations to the subsequent rotor) have been derived and shown to be significant.
A Modern Approach to Conceptual/Preliminary Design of Gas Turbine Based Propulsion Systems
Authors: Shahroudi Kamran Eftekhari
Published: February 2015

This paper describes the development and implementation of the Natural Design Cycle to Conceptual/Preliminary Design of gas-turbine-based aircraft engines. The Natural Design Cycle is a high speed design optimization cycle within which the human designer is actively employed.

The CAGEDR (Computer Aided General Engine Design) was developed at Delft TU to closely mimic the Natural Design Cycle. The main objective of this exercise was to obtain a modern and efficient tool to assist engineers in the conceptual/preliminary phase of gas turbine based aircraft engine mechanical and thermodynamic design, by automating many of the laborious tasks involved while leaving all intuitive and decision making tasks to the human designer.

The topics discussed herein will be of interest to other propulsion software and/or CAD developers, Among them,

• The Natural Design Cycle and its advantages

• generation High Speed (or Real Time) Engine Models in the form of ANSI C Source Code

• Integration with Aircraft Design/Analysis

• Real Time Movement Through Design Space for “Human in the Loop” optimization (the Dyn-Carp and the Dyn-Hist modules)

• The role of Graphic User Interface for defining engine models
Secondary Flow Development Downstream of a Blade Endwall Corner
Authors: Abdulla-Altaii A. Karim , Raj Rishi S.
Published: February 2015

The flow downstream of the corner formed by a blade and a flat plate was investigated experimentally. A single dominant horseshoe vortex was identified which persisted more than one chord length downstream of the blade trailing edge. A smaller and weaker corner vortex was also identified. It dissipated and ceased to exist by a downstream axial location of approximately 0.2C (C= chord length). There was no evidence of stress induced vortices in the region of this investigation. The secondary flow system redistributes the mean flow momentum and distorts total pressure profiles and contours. In planes parallel to the flat plate, total pressure values were found to be higher than the undisturbed two-dimensional boundary layer at that height. Surface static pressure was found to be at its maximum at the blade trailing edge location and it decreased in both the downstream and transverse directions. There was no significant static pressure variation in the spanwise direction. Downstream of the blade trailing edge, under the domain of the horseshoe vortex, local wall shear stress increased to values exceeding the values found in the undisturbed boundary layer at that axial location. However, a 20% reduction in the net wall skin-friction (wall shear stress integrated over the flat plate surface) was observed.
Exergy Analysis of Integrated Gas-Steam Cycle
Authors: Singh Onkar , Yadav R.
Published: February 2015

The thermodynamic analysis of integrated gas/steam cycle has been carried out on the basis of second law of thermodynamics. The exergy analysis provides a viable understanding of the influence of various parameters on the distribution of losses in the constituent components of the cycle. The paper also provides the insight into the influence of changing operating parameters on the performance of the waste heat recovery boiler, which in turn questions the viability of the integrated gas/steam cycle.
Increasing Heat Supply Availability From Combined Heat and Power Plants in Case of Main Components Failure
Authors: Linnemeijer Mathieu J. J.
Published: February 2015

Combined heat and power plants are used to supply the heat and power needed for processes. In most cases these processes require an uninterrupted heat and power supply. For the design of such plant, considerations have to be made as to how the heat and power supply can be maintained if one of the main components, the gas turbine, the HRSG or the steam turbine is not available or trips. The paper will give solutions to increase the availability of the steam supply to the process as applied in a number of projected and executed plant designs.
Externally Fired Combustion Cycle (EFCC) a DOE Clean Coal V Project: Effective Means of Rejuvenation for Older Coal-Fired Stations
Authors: LaHaye P. G. , Bary M. R.
Published: February 2015

A long term program was initiated in 1987 to develop an electric utility indirect coal-fired gas turbine combined cycle. This initial program was supported primarily by U.S. electric utility organizations and had as a purpose the experimental assessment of a ceramic heat exchanger concept applied as a high pressure gas turbine air heater developed by Hague International.

The purpose of the initial phase of the development program was to determine if the ceramic materials, then available for use in the air heater, would withstand the high temperature 2200 F (1204 °C) corrosive environment produced by the combustion of coal. Also, in this initial phase, the program was intended to evaluate means of preventing the fouling of the air heater by fly ash. This experimental work was successful. A second phase of the program to build a 7-MW thermal input prototype was initiated in 1990 under the auspices of a cooperative agreement with the U.S. Department of Energy Morgantown Energy Technology Center (DOE-METC). This work was funded by a consortium of electric utilities, utility organizations, industrial organizations, state agencies, international entities, and the U.S. Department of Energy-METC. New members joined the existing Phase I Consortium to participate in funding the second phase. This second prototype phase is nearing completion and test results are to be available beginning mid-1994.

A third, or demonstration phase, of the indirect-fired gas turbine program was selected under the U.S. Clean Coal Technology Program Round V. in May, 1993. This demonstration phase is currently in the planning and preliminary engineering stage. The objective of this proposed demonstration phase is to repower an existing coal-fired power plant in the Pennsylvania Electric Company system at Warren, Pennsylvania (Figure 1). This paper describes the demonstration plant, and the anticipated role of the EFCC cycle in the power generation industry, as well as the performance and economic merits of the Warren repowering concept.
Assessment of Notches in Ceramic Components
Authors: Brückner-Foit A. , Heger A. , Munz D.
Published: February 2015

The failure probability of notched tensile bars is calculated using the multiaxial Weibull theory. The influence exerted by the stress concentration factor, the stress gradient in the notch root, and the Weibull exponent is analysed.
LM2500 Marine Gas Turbine Sealift Program Uprate
Authors: Brady Carl O.
Published: February 2015

This paper traces the evolution of the GE LM2500 gas turbine engine in the US Navy from its initial introductory 21,500 hp (16,033 kW) rating in DD-963 class destroyers to its current US Navy Sealift Program rating of 32,000 hp (23,863 kW). Improvements to the engine and required qualification testing to establish the ratings are discussed with particular emphasis on the recent 32,000 hp (23,863 kW) Sealift Program uprate.
Learning from the Starry Message: Using Galileo's Sidereus Nuncius in Introductory Astronomy Classes
Authors: Wiesner Matthew P.
Published: February 2015

Every introductory astronomy class encounters Galileo during the course as the first man to systematically study the sky with a telescope. Every Astronomy 101 student meets Galileo as one of the major catalysts behind the shift from the Ptolemaic to the Copernican system and as one of the great minds behind the scientific method. But most of the time Galileo is just an inset on page 17 with one of the canonical portraits, appearing in students' lists of six early astronomers that need to be memorized for the first exam. I have tried to find ways to overcome such shallow educational experiences in introductory astronomy. In order to bring students to a real encounter with Galileo, I have assigned reading of an excerpt from Galileo's Sidereus Nuncius, “The Starry Message,” followed by an inclass discussion of the text.
The Physics of Warfare
Authors: Giordano Gerardo
Published: February 2015

Recently, I was tasked with the creation and execution of a new themed general education physics class called The Physics of Warfare. In the past, I had used the theme of a class, such as the physics of sports medicine, as a way to create homework and in-class activities, generate discussions, and provide an application to demonstrate that physics isn't always abstract. It is true that the examples and applications in this warfare class practically wrote themselves, but I wanted more for my students. I wanted them to embrace the iterative nature of scientific understanding. I wanted them to yearn for the breakthroughs that lead to paradigm shifts. I wanted them to demand experimental verification of each novel idea. This paper discusses the formation and implementation of a conceptual physics course, full of in-class demonstrations and solidly rooted in the context of humankind's ever-evolving methods of waging war.
Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion II
Authors: Lee Scott
Published: February 2015

In the second paper1 of this series, the effect of transverse femoral stresses due to locomotion in theropod dinosaurs of different sizes was examined for the case of an unchanging leg geometry. Students are invariably thrilled to learn about theropod dinosaurs, and this activity applies the concepts of torque and stress to the issue of theropod locomotion. In this paper, our model calculation of Ref. 1 is extended to incorporate the fact that larger animals run with straighter legs. As in Ref. 1, students use geometric data for the femora of theropod dinosaurs to analyze their locomotion abilities. This can either be an in-class activity or given as a homework problem. Larger theropods are found to be less athletic in their movements than smaller theropods since the stresses in the femora of large theropods are closer to breaking their legs than smaller theropods.
What are students who earned a bachelor's degree in physics doing one year after graduation?
Authors: White Susan C.
Published: February 2015

Each year we attempt to contact each person who received a bachelor's degree in physics one year earlier to ask them what they are doing. New degree recipients typically follow one of two paths: enrolling in graduate school or entering the employment market. For the classes of 2011 and 2012 combined, nearly 60% chose to enroll in a graduate program; almost 40% of those opting for graduate school went into a field other than physics or astronomy. Only 4% of physics bachelor's degree recipients from the classes of 2011 and 2012 were still seeking employment one year after graduation.
Analyzing Oscillations of a Rolling Cart Using Smartphones and Tablets
Authors: Egri Sándor , Szabó Lóránt
Published: February 2015

It is well known that “interactive engagement” helps students to understand basic concepts in physics.1 Performing experiments and analyzing measured data are effective ways to realize interactive engagement, in our view. Some experiments need special equipment, measuring instruments, or laboratories, but in this activity we advocate student use of mobile phones or tablets to take experimental data. Applying their own devices and measuring simple phenomena from everyday life can improve student interest, while still allowing precise analysis of data, which can give deeper insight into scientific thinking and provide a good opportunity for inquiry-based learning.2
Analyzing planetary transits with a smartphone
Authors: Barrera-Garrido Azael
Published: February 2015

Today's smartphones are getting more sensors than ever as factory-installed accessories. The time when a luxury mobile phone had only vertical and GPS sensors is gone. New smartphones come equipped with multiple sensors for many physical parameters. Smartphones are becoming portable physics laboratory data loggers for a variety of measurements in mechanics, thermodynamics, electromagnetism, and optics. All sorts of possibilities are now open, provided their sensors are calibrated. Many examples using the sensors available in smartphones have been presented, mostly in this column and a few other publications, such as acceleration sensors,1–3 microphones,4,5 camera,6–8 and light sensors.9,10
Tunable effective constants of the one-dimensional piezoelectric phononic crystal with internal connected electrodes
Authors: Kutsenko A. A. , Shuvalov A. L. , Poncelet O. , Darinskii A. N.
Published: February 2015

One-dimensional propagation of a longitudinal wave through an infinite piezoelectric periodically layered structure is considered. The unit cell consists, in general, of piezoelectric multilayers separated by thin electrodes which are connected through a capacitor with capacity Cj that plays the role of the external electric control providing tunability of the mechanical properties. The main focus of the present study is on the effective properties characterizing the homogenized medium. Due to the electric boundary conditions, the 4×4 transfer matrix M through the period T can be reduced to 2 × 2 dimension governing the mechanical fields only. As a result, the homogenized medium is pure elastic though its effective material parameters depend on the piezoelectric and dielectric coefficients of the actual piezoelectric medium, as well as on Cj. The effective parameters and the impedance in the low-frequency limit ω→0 and at finite frequency are obtained and analyzed.
Hemispherical double-layer time reversal imaging in reverberant and noisy environments at audible frequencies
Authors: Lobréau Stéphanie , Bavu Éric , Melon Manuel
Published: February 2015

Time reversal is a widely used technique in wave physics, for both imaging purposes and experimental focusing. In this paper, a complete double-layer time reversal imaging process is proposed for in situ acoustic characterization of non-stationary sources, with perturbative noise sources and reverberation. The proposed method involves the use of a hemispherical array composed of pressure-pressure probes. The complete set of underlying optimizations to sonic time reversal imaging is detailed, with regard to space and time reconstruction accuracy, imaging resolution and sensitivity to reverberation, and perturbative noise. The proposed technique is tested and compared to more conventional time reversal techniques through numerical simulations and experiments. Results demonstrate the ability of the proposed method to back-propagate acoustic waves radiated from non-stationary sources in the volume delimited by the measurement array with a high precision both in time and space domains. Analysis of the results also shows that the process can successfully be applied in strongly reverberant environments, even with poor signal-to-noise ratio.
Release from informational masking in a monaural competing-speech task with vocoded copies of the maskers presented contralaterally
Authors: Bernstein Joshua G. W. , Iyer Nandini , Brungart Douglas S.
Published: February 2015

Single-sided deafness prevents access to the binaural cues that help normal-hearing listeners extract target speech from competing voices. Little is known about how listeners with one normal-hearing ear might benefit from access to severely degraded audio signals that preserve only envelope information in the second ear. This study investigated whether vocoded masker-envelope information presented to one ear could improve performance for normal-hearing listeners in a multi-talker speech-identification task presented to the other ear. Target speech and speech or non-speech maskers were presented unprocessed to the left ear. The right ear received no signal, or either an unprocessed or eight-channel noise-vocoded copy of the maskers. Presenting the vocoded maskers contralaterally yielded significant masking release from same-gender speech maskers, albeit less than in the unprocessed case, but not from opposite-gender speech, stationary-noise, or modulated-noise maskers. Unmasking also occurred with as few as two vocoder channels and when an attenuated copy of the target signal was added to the maskers before vocoding. These data show that delivering masker-envelope information contralaterally generates masking release in situations where target-masker similarity impedes monaural speech-identification performance. By delivering speech-envelope information to a deaf ear, cochlear implants for single-sided deafness have the potential to produce a similar effect.
Target strengths of two abundant mesopelagic fish species
Authors: Scoulding Ben , Chu Dezhang , Ona Egil , Fernandes Paul. G.
Published: February 2015

Mesopelagic fish of the Myctophidae and Sternoptychidae families dominate the biomass of the oceanic deep scattering layers and, therefore, have important ecological roles within these ecosystems. Interest in the commercial exploitation of these fish is growing, so the development of techniques for estimating their abundance, distribution and, ultimately, sustainable exploitation are essential. The acoustic backscattering characteristics for two size classes of Maurolicus muelleri and Benthosema glaciale are reported here based on swimbladder morphology derived from digitized soft x-ray images, and empirical (in situ) measurements of target strength (TS) derived from an acoustic survey in a Norwegian Sea. A backscattering model based on a gas-filled prolate spheroid was used to predict the theoretical TS for both species across a frequency range between 0 and 250 kHz. Sensitivity analyses of the TS model to the modeling parameters indicate that TS is rather sensitive to the viscosity, swimbladder volume ratio, and tilt, which can result in substantial changes to the TS. Theoretical TS predictions close to the resonance frequency were in good agreement (±2 dB) with mean in situ TS derived from the areas acoustically surveyed that were spatially and temporally consistent with the trawl information for both species.
Radiation efficiency of damped plates
Authors: Kou Yiwei , Liu Bilong , Tian Jing
Published: February 2015

The radiation efficiency of damped plates is discussed in this letter. Below the critical frequency of a plate, numerical results show that the radiation efficiency is much influenced by damping. Some modifications of the classical formulas given by Cremer for an infinite plate and Leppington for a finite rectangular plate are proposed to include the influence of the damping on the radiation efficiency.
Imaging multiple local changes in heterogeneous media with diffuse waves
Authors: Planès Thomas , Larose Eric , Rossetto Vincent , Margerin Ludovic
Published: February 2015

This study focuses on imaging local changes in heterogeneous media. The method employed is demonstrated and validated using numerical experiments of acoustic wave propagation in a multiple scattering medium. Changes are simulated by adding new scatterers of different sizes at various positions in the medium, and the induced decorrelation of the diffuse (coda) waveforms is measured for different pairs of sensors. The spatial and temporal dependences of the decorrelation are modeled through a diffuse sensitivity kernel, based on the intensity transport in the medium. The inverse problem is then solved with a linear least square algorithm, which leads to a map of scattering cross section density of the changes.
Perceptual susceptibility to acoustic manipulations in speaker discrimination
Authors: Sell Gregory , Suied Clara , Elhilali Mounya , Shamma Shihab
Published: February 2015

Listeners' ability to discriminate unfamiliar voices is often susceptible to the effects of manipulations of acoustic characteristics of the utterances. This vulnerability was quantified within a task in which participants determined if two utterances were spoken by the same or different speakers. Results of this task were analyzed in relation to a set of historical and novel parameters in order to hypothesize the role of those parameters in the decision process. Listener performance was first measured in a baseline task with unmodified stimuli, and then compared to responses with resynthesized stimuli under three conditions: (1) normalized mean-pitch; (2) normalized duration; and (3) normalized linear predictive coefficients (LPCs). The results of these experiments suggest that perceptual speaker discrimination is robust to acoustic changes, though mean-pitch and LPC modifications are more detrimental to a listener's ability to successfully identify same or different speaker pairings. However, this susceptibility was also found to be partially dependent on the specific speaker and utterances.
Intraglottal velocity and pressure measurements in a hemilarynx model
Authors: Oren Liran , Gutmark Ephraim , Khosla Sid
Published: February 2015

Determining the mechanisms of self-sustained oscillation of the vocal folds requires characterization of the pressures produced by intraglottal aerodynamics. Because most of the intraglottal aerodynamic forces cannot be measured in a tissue model of the larynx, current understanding of vocal fold vibration mechanism is derived from mechanical, analytical, and computational models. Previous studies have computed intraglottal pressures from measured intraglottal velocity fields and intraglottal geometry; however, this technique for determining pressures is not yet validated. In this study, intraglottal pressure measurements taken in a hemilarynx model are compared with pressure values that are computed from simultaneous velocity measurements. The results showed that significant negative pressure formed near the superior aspect of the folds during closing, which agrees with previous measurements in other hemilarynx models. Intraglottal velocity measurements show that the flow near the superior aspect separates from the glottal wall during closing and may develop into a vortex, which further augments the magnitude of negative pressure. Intraglottal pressure distributions, computed by solving the pressure Poisson equation, showed good agreement with pressure measurements. The match between the pressure computations and its measurements validates the current technique, which was previously used to estimate intraglottal pressure distribution in a full larynx model.
Statistical properties of linear prediction analysis underlying the challenge of formant bandwidth estimation
Authors: Mehta Daryush D. , Wolfe Patrick J.
Published: February 2015

Formant bandwidth estimation is often observed to be more challenging than the estimation of formant center frequencies due to the presence of multiple glottal pulses within a period and short closed-phase durations. This study explores inherently different statistical properties between linear prediction (LP)–based estimates of formant frequencies and their corresponding bandwidths that may be explained in part by the statistical bounds on the variances of estimated LP coefficients. A theoretical analysis of the Cramér-Rao bounds on LP estimator variance indicates that the accuracy of bandwidth estimation is approximately twice as low as that of center frequency estimation. Monte Carlo simulations of all-pole vowels with stochastic and mixed-source excitation demonstrate that the distributions of estimated LP coefficients exhibit expectedly different variances for each coefficient. Transforming the LP coefficients to formant parameters results in variances of bandwidth estimates being typically larger than the variances of respective center frequency estimates, depending on vowel type and fundamental frequency. These results provide additional evidence underlying the challenge of formant bandwidth estimation due to inherent statistical properties of LP-based speech analysis.
Analysis of Ganciclovir-Resistant Human Herpesvirus 6B Clinical Isolates Using Quenching Probe PCR Methodology
Authors: Hiramatsu Hiroyuki , Suzuki Ryota , Yamada Shigeki , Ihira Masaru , Isegawa Yuji , Kawamura Yoshiki , Matsuoka Erina , Miura Hiroki , Yoshikawa Tetsushi
Published: February 2015

Quenching probe PCR (QP-PCR) analysis was used to determine the frequency of ganciclovir (GCV) resistance among clinical isolates of human herpesvirus 6B (HHV-6B) obtained from patients with primary viral infection and viral reactivation. Forty-two HHV-6B clinical isolates were repeatedly recovered from 15 hematopoietic stem cell transplant (HSCT) recipients, and 20 isolates were recovered from 20 exanthem subitum (ES) patients. Of the 15 HSCT recipients, 9 received GCV during the observation period; however, none of the ES patients were treated with GCV. Two established laboratory strains, Z29 and HST, were used as standards in this study. Regions 1 and 2 of the U69 gene of all of the clinical isolates demonstrated the same melting temperature as regions 1 and 2 of the Z29 strain. For region 3, the melting temperatures of all clinical isolates fell between the melting temperature of the plasmid containing the A462D single nucleotide polymorphism (SNP) and the melting temperature of the Z29 strain, and the melting temperatures profiles of all clinical isolates were similar to the melting temperature profile of the Japanese HST strain. As expected, none of the 20 clinical isolates recovered from the ES patients and the 14 isolates recovered from the HSCT recipients who did not receive GCV treatment carried the six known SNPs associated with GCV resistance. Interestingly, these six SNPs were not detected in the 28 clinical isolates recovered from the 9 HSCT recipients who received GCV. Additional sequence analysis of the U69 gene from the 15 representative isolates from the 15 HSCT recipients identified other SNPs. These SNPs were identical to those identified in the HST strain. Therefore, the rate of emergence of GCV-resistant HHV-6B strains appears to be relatively low, even in HSCT recipients treated with GCV.
Colistin Resistance Mechanisms in Klebsiella pneumoniae Strains from Taiwan
Authors: Cheng Yi-Hsiang , Lin Tzu-Lung , Pan Yi-Jiun , Wang Yu-Ping , Lin Yi-Tsung , Wang Jin-Town
Published: February 2015

Colistin is one of the antibiotics of last resort for the treatment of carbapenem-resistant
Klebsiella pneumoniae
infection. This study showed that capsular type K64 (50%) and ST11 (53.9%) are the prevalent capsular and sequence types in the colistin-resistant strains in Taiwan. The interruption of transcripts (38.5%) and amino acid mutation (15.4%) in
mgrB
are the major mechanisms contributing to colistin resistance. In addition, novel single amino acid changes in MgrB (Stop48Tyr) and PhoQ (Leu26Pro) were observed to contribute to colistin resistance.
Simultaneous Administration of 2-Aminoethyl Diphenylborinate and Chloroquine Reverses Chloroquine Resistance in Malaria Parasites
Authors: Mossaad Ehab , Furuyama Wakako , Enomoto Masahiro , Kawai Satoru , Mikoshiba Katsuhiko , Kawazu Shin-ichiro
Published: February 2015

A nearly complete reversal of chloroquine (CQ) resistance in the CQ-resistant
Plasmodium falciparum
K-1 strain, with a significant decrease in the mean ± standard deviation (SD) 50% inhibitory concentration (IC
50
) from 1,050 ± 95 nM to 14 ± 2 nM, was achieved
in vitro
by the simultaneous administration of 2-aminoethyl diphenylborinate (2-APB). The CQ resistance-reversing activity of 2-APB, which showed the same efficacy as verapamil, was also observed in an
in vivo
mouse infection model with the CQ-resistant
Plasmodium chabaudi
AS(30CQ) strain.
Adhesive Properties of YapV and Paralogous Autotransporter Proteins of Yersinia pestis
Authors: Nair Manoj K. M. , De Masi Leon , Yue Min , Galván Estela M. , Chen Huaiqing , Wang Fang , Schifferli Dieter M.
Published: February 2015

Yersinia pestisis the causative agent of plague. This bacterium evolved from an ancestral enteroinvasiveYersinia pseudotuberculosisstrain by gene loss and acquisition of new genes, allowing it to use fleas as transmission vectors. Infection frequently leads to a rapidly lethal outcome in humans, a variety of rodents, and cats. This study focuses on theY. pestisKIMyapVgene and its product, recognized as an autotransporter protein by its typical sequence, outer membrane localization, and amino-terminal surface exposure. Comparison ofYersiniagenomes revealed that DNA encoding YapV or each of three individual paralogous proteins (YapK, YapJ, and YapX) was present as a gene or pseudogene in a strain-specific manner and only inY. pestisandY. pseudotuberculosis. YapV acted as an adhesin for alveolar epithelial cells and specific extracellular matrix (ECM) proteins, as shown with recombinantEscherichia coli,Y. pestis, or purified passenger domains. Like YapV, YapK and YapJ demonstrated adhesive properties, suggesting that their previously relatedin vivoactivity is due to their capacity to modulate binding properties ofY. pestisin its hosts, in conjunction with other adhesins. A differential host-specific type of binding to ECM proteins by YapV, YapK, and YapJ suggested that these proteins participate in broadening the host range ofY. pestis. A phylogenic tree including 36Y. pestisstrains highlighted an association between the gene profile for the four paralogous proteins and the geographic location of the corresponding isolated strains, suggesting an evolutionary adaption ofY. pestisto specific local animal hosts or reservoirs.
Species-Specific Dynamic Responses of Gut Bacteria to a Mammalian Glycan
Authors: Raghavan Varsha , Groisman Eduardo A.
Published: February 2015

The mammalian intestine provides nutrients to hundreds of bacterial species. Closely related species often harbor homologous nutrient utilization genes and cocolonize the gut, raising questions regarding the strategies mediating their stable coexistence. Here we reveal that relatedBacteroidesspecies that can utilize the mammalian glycan chondroitin sulfate (CS) have diverged in the manner in which they temporally regulate orthologous CS utilization genes. Whereas certainBacteroidesspecies display a transient surge in CS utilization transcripts upon exposure to CS, other species exhibit sustained activation of these genes. Remarkably, species-specific expression dynamics are retained even when the key players governing a particular response are replaced by those from a species with a dissimilar response.Bacteroidesspecies exhibiting distinct expression behaviors in the presence of CS can be cocultured on CS. However, they vary in their responses to CS availability and to the composition of the bacterial community when CS is the sole carbon source. Our results indicate that diversity resulting from regulation of polysaccharide utilization genes may enable the coexistence of gut bacterial species using a given nutrient.

IMPORTANCEGenes mediating a specific task are typically conserved in related microbes. For instance, gutBacteroidesspecies harbor orthologous nutrient breakdown genes and may face competition from one another for these nutrients. How, then, does the gut microbial composition maintain such remarkable stability over long durations? We establish that in the case of genes conferring the ability to utilize the nutrient chondroitin sulfate (CS), microbial species vary in how they temporally regulate these genes and exhibit subtle growth differences on the basis of CS availability and community composition. Similarly to how differential regulation of orthologous genes enables related species to access new environments, gut bacteria may regulate the same genes in distinct fashions to reduce the overlap with coexisting species for utilization of available nutrients.
Electron Tomography Imaging of Surface Glycoproteins on Human Parainfluenza Virus 3: Association of Receptor Binding and Fusion Proteins before Receptor Engagement
Authors: Gui Long , Jurgens Eric M. , Ebner Jamie L. , Porotto Matteo , Moscona Anne , Lee Kelly K.
Published: February 2015

In order to deliver their genetic material to host cells during infection, enveloped viruses use specialized proteins on their surfaces that bind cellular receptors and induce fusion of the viral and host membranes. In paramyxoviruses, a diverse family of single-stranded RNA (ssRNA) viruses, including several important respiratory pathogens, such as parainfluenza viruses, the attachment and fusion machinery is composed of two separate proteins: a receptor binding protein (hemagglutinin-neuraminidase [HN]) and a fusion (F) protein that interact to effect membrane fusion. Here we used negative-stain and cryo-electron tomography to image the 3-dimensional ultrastructure of human parainfluenza virus 3 (HPIV3) virions in the absence of receptor engagement. We observed that HN exists in at least two organizations. The first were arrays of tetrameric HN that lacked closely associated F proteins: in these purely HN arrays, HN adopted a “heads-down” configuration. In addition, we observed regions of complex surface density that contained HN in an apparently extended “heads-up” form, colocalized with prefusion F trimers. This colocalization with prefusion F prior to receptor engagement supports a model for fusion in which HN in its heads-up state and F may interact prior to receptor engagement without activating F, and that interaction with HN in this configuration is not sufficient to activate F. Only upon receptor engagement by HN’s globular head does HN transmit its activating signal to F.

IMPORTANCE
Human parainfluenza virus 3 (HPIV3) is an enveloped, ssRNA virus that can cause serious respiratory illness, especially in children. HPIV3, like most other paramyxoviruses, uses two specialized proteins to mediate cell entry: the fusion protein (F) and the receptor binding protein, hemagglutinin-neuraminidase (HN). F becomes activated to mediate fusion during entry when it is triggered by a signal from HN. Here we used electron tomography to reconstruct the 3-dimensional ultrastructure of HPIV3. From these structures, we could discern the distribution and, in some cases, conformation of HN and F proteins, which provided an understanding of their interrelationship on virions. HN is found in arrays alone in one conformation and interspersed with prefusion F trimers in another. The data support a model of paramyxovirus membrane fusion in which HN associates with F before receptor engagement, and receptor engagement by the globular head of HN switches the HN-F interaction into one of fusion activation.
Cushing's disease masking coincidental steroid-responsive diseases
Authors: Rehman H U , Walton C , Atkin S
Published: February 2015

Two cases of Cushing's disease are presented. In both cases successful treatment was followed by the development of a steroid-responsive disease condition, a seronegative arthritis in the first case and retinal vasculitis in the second. It is likely that both these conditions were unmasked by the fall in the endogenous steroid levels following the successful treatment of the Cushing's disease by trans-sphenoidal hypophysectomy.
Treatment for morbid obesity
Authors: Carmichael A R
Published: February 2015

There is no single unifying theory to explain the aetiology of obesity but several environmental factors, such as decreased physical activity and increased fat intake may contribute to its development in genetically predisposed individuals. Dietary and pharmacological treatments of morbid obesity have been proven to be unsuccessful. Modern surgical treatments have been shown to be effective in achieving significant weight loss with consequent reduction in morbidity. Despite the fact that surgical treatment of morbid obesity is the only therapeutic form that has stood the test of time, it still remains a crisis-driven form of therapy in the UK. It is probable that a better understanding of the aetiology and physiology of obesity may lead to the development of an effective pharmacological treatment of obesity in the future. However, until then, surgical treatment of morbid obesity should be considered as an effective and efficient way of treatment in selected cases.
Training and supervision needs and experience: a longitudinal, cross-sectional survey of accident and emergency department senior house officers
Authors: Dale Jeremy , Williams Susan , Wellesley Amanda , Glucksman Edward
Published: February 2015

The aim of this study was to investigate senior house officers' (SHOs) perceptions about their training needs, satisfaction with teaching and supervision, and the relationship this has with psychological distress levels. All 171 SHOs employed within 27 accident and emergency (A&E) departments in the South Thames region were sent questionnaires at the start of their attachments in A&E, at the end of months four and six. The questionnaires asked SHOs to rate on visual analogue scales their perceived need for further training for 23 clinical and practical activities relevant to A&E practice. At the end of the fourth month SHOs were asked to indicate who had provided them with the most valuable teaching and supervision, indicate their satisfaction levels with training received, and suggest ways to improve teaching and supervision. SHOs' psychological distress levels were measured in all three questionnaires.

Overall, satisfaction with supervision and training was mixed. SHOs perceived greatest need for further training in areas encountered less frequently in A&E. Registrars were the most valued providers of supervision and teaching. Increased numbers of middle grade staff and protected study time were suggested as ways to improve supervision and teaching. SHOs with higher scores for training need at the end of their attachment in A&E expressed significantly less satisfaction with training and higher psychological distress levels. The variation between SHOs' perceptions of training needs indicates the importance of tailoring training and supervision to individual requirements.
Evaluation of the one-minute ultra-rapid urease test for diagnosing Helicobacter pylori
Authors: Misra S P , Misra Vatsala , Dwivedi Manisha , Singh Premala Anthony , Bhargava Vanita , Jaiswal Pramod K
Published: February 2015

To determine the diagnostic accuracy of the one-minute ultra-rapid urease test for diagnosing Helicobacter pylori infection, two biopsies were taken from both the gastric corpus and antrum from 1000 patients undergoing upper gastrointestinal endoscopy. All the biopsies were subjected to the one-minute ultra-rapid urease test before imprint smears were prepared from them. Thereafter, the biopsies were fixed in 10% formalin and histological sections were examined for the presence of H pylori by a pathologist who was not aware of the clinical details or the results of the urease test. The prevalence of H pylori in the gastric antrum and corpus was 86.7% and 53.3%, respectively. The sensitivity, specificity, positive and negative predictive value and the overall diagnostic accuracy of the ultra-rapid urease test to diagnoseH pylori infection in the gastric antrum were 92%, 100%, 100%, 66%, and 93%, respectively. The corresponding figures for the gastric corpus were 83%, 100%, 100%, 85%, and 91%, respectively. It is concluded that the one-minute ultra-rapid urease test has a high sensitivity and specificity and may be used as a rapid and cheap method to diagnose H pylori infection.
Hepatitis G virus infection as a possible causative agent of community-acquired hepatitis and associated aplastic anaemia
Authors: Crespo J , de las Heras B , Rivero M , Lozano J L , Fábrega E , Pons-Romero F
Published: February 2015

Aplastic anaemia complicating hepatitis is a rare but well-documented phenomenon; however in many patients the cause remains unknown. We present a 24-year-old man with a well-defined community-acquired hepatitis, probably due to hepatitis G virus (HGV), who developed severe aplastic anaemia. In this case, the absence of other agents likely to cause the clinical manifestations, and the detection of HGV RNA at the time of illness, clearly point to this agent as being responsible for both the hepatitis and the aplastic anaemia. Further studies in serial serum samples and meticulous evaluation of the disorders associated with the infection will be needed to prove or dispute a causal association of HGV and aplastic anaemia.
Good prognosis in thyroid cancer found incidentally at surgery for thyrotoxicosis
Authors: Vini Louiza , Hyer Stephen , Pratt Brenda , Harmer Clive
Published: February 2015

An analysis of the outcome of thyroid carcinoma incidentally discovered in patients undergoing surgery for hyperthyroidism is presented. Among 986 patients with differentiated thyroid cancer, 23 had presented with symptoms and signs of hyperthyroidism. Graves' disease was diagnosed in 11, multinodular goitre in eight and toxic adenoma in four. Following thyroidectomy, histology revealed papillary (18), follicular (four) and Hurthle cell (one) carcinoma. Tumour size ranged from 4 mm to 5.5 cm, multifocality was detected in three patients, and lymph node involvement in one. Two patients (one with associated Graves' disease, one with multinodular goitre) relapsed locally and required further surgery; one developed distant metastases and died 7 years after initial presentation. Two patients died of unrelated causes; the remaining 20 patients are alive and well with a median follow-up of 16 (1–34) years. Differentiated thyroid cancer found incidentally at surgery for hyperthyroidism has a good prognosis.
Orthostatic haemodynamic responses in acute stroke
Authors: Panayiotou B , Reid J , Fotherby M , Crome P
Published: February 2015

Little is known about orthostatic blood pressure regulation in acute stroke. We determined postural haemodynamic responses in 40 patients with acute stroke (mild or moderate severity) and 40 non-stroke control in-patients, at two days (‘Day 1’) and one week (‘Week 1’) post-admission. Following a 10-minute supine rest and baseline readings, subjects sat up and blood pressure and heart rate were taken for 5 minutes. The procedure was repeated with subjects moving from supine to the standing posture. Haemodynamic changes from supine data were analysed. On standing up, the control group had a transient significant fall in mean arterial blood pressure on Day 1 but not Week 1. No significant changes were seen on either day when sitting up. In contrast to controls, the stroke group showed increases in mean arterial blood pressure on moving from supine to the sitting and standing positions on both days. Persistent postural hypotension defined as ⩾20 mmHg systolic fall occurred in <10% of either of the study groups on both days. Sitting and standing heart rates in both groups were significantly faster than supine heart rate on both days. The orthostatic blood pressure elevation is consistent with sympathetic nervous system overactivity which has been reported in acute stroke. Upright positioning as part of early rehabilitation and mobilisation following mild-to-moderate stroke would, therefore, not predispose to detrimental postural reductions in blood pressure.
Mature bone metaplasia in abdominal wall scar
Authors: Daoud R A , Watkins M J , Brown G , Carr N
Published: February 2015

A 58-year-old man who had had three laparotomies for gastric surgery, developed a painful mass in the abdominal wall scar. Radiology confirmed bone formation in the scar. The bone was excised and the wound repaired. Histology confirmed metaplastic mature bone formation. This case draws the attention to the clinical condition of bone formation in midline scars. Clinically, it should be differentiated from scar recurrence following surgery for abdominal malignancy.
Gynaecomastia as a presenting feature of thyrotoxicosis
Authors: Chan W B , Yeung V T F , Chow C C , So W Y , Cockram C S
Published: February 2015

The association between gynaecomastia and thyrotoxicosis is well recognised. However, the reported frequency of the association is variable, partly depending upon the defining criteria used. Here we report two patients with thyrotoxicosis in whom gynaecomastia was the presenting feature. Both patients had other contributing factors, which are assumed to have predisposed to gynaecomastia. In both patients, the gynaecomastia resolved with successful treatment of the thyrotoxicosis. When gynaecomastia is a presenting, or prominent feature of thyrotoxicosis, the possibility of additional underlying pathology should be considered.
Anthracycline-induced cardiomyopathy
Authors: Fisher N G , Marshall A J
Published: February 2015

Anthracycline cardiomyopathy is less frequently encountered nowadays, due to the well-recognised dose limitations and cardiac monitoring protocols used by chemotherapy centres. However, it is a condition that will persist due to the sensitivity of some patients to these drugs and the necessity for large doses to be used for certain individuals. We have demonstrated the benefit of angiotensin-converting enzyme inhibitor therapy and would consider introducing these compounds at the earliest opportunity. The use of probucol and vitamins as antioxidants capable of preventing the onset of cardiomyopathy in humans appears to require further investigation but may significantly reduce the incidence of this condition in the future.