bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Numerical Analysis of Steam-Oxygen Fluidized Gasifier Feeding a Combined SOFC/ORC Power Plant
Authors: Borello Domenico , Di Carlo Andrea , Marchegiani Andrea , Rispoli Franco , Tortora Eileen
Published: November 2013

The aim of this work is to experimentally and numerically analyze the performance of a combined power plant, composed by a steam oxygen fluidized bed biomass gasifier fed by woods, a Solid Oxide Fuel Cell (SOFC) and an Organic Rankine Cycle (ORC). The gasifier model is developed and validated by means of experimental activities carried out with a bench scale gasifier in our lab. Different compounds (Benzene, Toluene, Naphthalene, Phenols) were chosen to analyze the tar evolution in the gaseous stream during the gasification process. Hot gas cleaning (based on catalytic ceramic filter candles inserted in the freeboard of the gasifier - UNIQUE concept) is adopted to remove tar and particulate at high temperature from the fuel gas stream. The numerical analysis is carried out by means of the software Aspen Plus®. In particular, the SOFC and the gasifier are modelled using proper developed Fortran subroutines interfaced to the basic software. The adopted SOFC model was already validated by the authors in previous works. Finally, a realistic ORC is modelled. Different moisture contents in the range of 10–30 % (i.e. in a deviation of 10% around the usual wood moisture content of 20%) are investigated in the simulations, as also the degree of purity of the oxygen used in the power plant (between 25 and 95%, rest N2). The power requirement for the production of pure oxygen for this kind of gasification technology leads to a reduction of the electrical efficiency of the whole power plant. For this reason a sensitivity analysis was conducted to find the optimal operation conditions in order to maximise the syngas content in the produced gas (H2, CO) maintaining a high overall electrical efficiency.
Evolution of Generic Vanelets Applied to a High Pressure Compressor
Authors: Loos Andreas , Mayenberger Tobias , Danner Florian , Kau Hans-Peter
Published: November 2013

The flow field of high pressure compressors is strongly influenced by secondary flow phenomena which lead to performance degradations. A significant fraction of the associated losses arises from tip as well as hub clearance vortices and their interaction with the main flow. In order to decrease the negative effect of clearance vortices, the application of vanelets, winglet-like structures attached to the tips of a cantilevered stator, is studied within the present paper. Different vanelets of generic design are applied to the stator and evaluated with respect to their aerodynamic effect by comparison against a datum configuration. The model comprises the investigated stator enclosed between two rotating blade rows. Detailed insight into the underlying phenomena is provided by numerical investigations with the compressible Reynolds-averaged Navier-Stokes equations. The structures led to an increased efficiency at the aerodynamic design point due to the suppression of the clearance mass flow in combination with a reduced vortex cross section. Under strongly throttled conditions a so called vanelet corner stall developed, which induced blockage near hub. Thus the main flow was displaced towards casing enhancing stable operation of the downstream rotor. Surge margin was consequently increased.
Performance Evaluation of Non-Uniformly Fouled Axial Compressor Stages by Means of Computational Fluid Dynamic Analyses
Authors: Aldi Nicola , Morini Mirko , Pinelli Michele , Spina Pier Ruggero , Suman Alessio , Venturini Mauro
Published: November 2013

In this paper, three-dimensional numerical simulations are carried out to evaluate the effect of fouling on an axial compressor stage. A numerical model of the NASA Stage 37, validated in previous papers of the same authors against experimental data available from literature, is used as a case study.

The occurrence of fouling is simulated by imposing different spanwise distributions of surface roughness, in order to analyze its effect on compressor performance. To this aim, both the stage performance maps of the fouled compressor and the spanwise distribution of work and losses are analyzed and discussed. Moreover, the definition of an averaged roughness parameter is suggested, to characterize the different roughness distributions.

The results show that the drop of overall performance can actually be predicted by means of the numerical model. Moreover, detailed information about fluid-dynamic phenomena can be analyzed on the basis of the actual distribution of surface roughness on rotor blades.
Alstom Gas Turbine Technology Developments
Authors: Marchmont Caroline , Florjancic Stefan , Kappis Wolfgang
Published: November 2013

In preparation for the next generation combined cycles, gas turbine technology development needs to continue to lower the lifecycle costs through increased efficiency, reduced first costs, extended maintenance cycles, and reduced emissions. It must also develop fast ramping capability, account for a wider variation in fuel composition and provide emission and performance effective part load operation. These needs will be met by refining state of the art technologies and adding new technologies. This paper will provide an overview of the recent research and development activities, the approach to bring them into a product and the resulting trend in Alstom gas turbine technologies.
Experimental and CFD Studies of NGV Endwall Cooling
Authors: Thomas Mitra , Kirollos Benjamin , Jackson Dougal , Povey Thomas
Published: November 2013

For engines operating at high turbine entry temperatures it is increasingly important to cool the high pressure nozzle guide vane (HP NGV) endwalls. This is particularly so for low NOx combustors operating with flatter outlet temperature distributions.

Double-row arrangements of film/ballistic cooling holes upstream of the NGV passage have been employed in production engines. Optimisation of such systems is non-trivial, however, due to the complex nature of the flow in the endwall region. Previous studies have reported that strong cross passage pressure gradients lead to migration of coolant flow and boundary layer flow within the passage. In addition the vane potential field effects lead to non-uniform blowing ratios for holes upstream of the vanes. It has also been reported that inlet total pressure and turbulence profiles have a significant effect on the development of the film cooling layer.

In this study, endwall film cooling flows are studied experimentally in a large-scale low-speed cascade tunnel with engine-realistic combustor geometry and turbulence profiles. At very low blowing ratios mild cross-passage migration effects are observed. At higher blowing ratios more realistic of the engine situation no cross-passage migration is observed. This finding is somewhat contrary to the classical view of endwall secondary flow, which is presented as significant at the scale of the vane passage by several authors. The difference arises in part because of the thinning of the boundary layer due to strong acceleration in the vane inlet contraction. The findings are further supported by CFD simulations.

Methods of improving conventional double-row systems to offer improved cooling of the endwall are also discussed.
Experimental Analysis of Abradable Labyrinth Seal Leakage With Simulated Groove: Part 2
Authors: Innocenti Luca , Ricupero Stefania , Pandit Rajeev Kumar , Sheng Nuo
Published: November 2013

In the secondary flow path of centrifugal compressors, abradable seals are in high demand when higher efficiency is the main requirement. This is because abradable seals can maintain very tight clearances between static and rotating components compared to other sealing technology. However, due to the rubbing of the teeth into the abradable material, some grooves can form. The flow physics and mass leakage of abradable seals are strongly dependent on the presence of these grooves and their shape. For cases where no grooves are present, seal leakage is mainly a function of inlet pressure, pressure ratio across the seal and tooth radial clearance. Once grooves are formed, the flow physics and seal leakage also are a function of groove dimensions, tooth clearance and tooth axial position inside the groove.

The scope of the present paper is to describe the experimental campaign that has been performed to validate the numerical analysis of part 1 of the paper [1]. The experimental test matrix investigates the groove and teeth positioning effects on seal leakages. To achieve higher accuracy, the key geometric parameters, such as radial and axial gaps, were controlled in the test sample during the tests. For cases where grooves are present the experimental measurements reveal that flow field strongly depends on groove dimensions, tooth radial clearance and tooth axial position. The authors, finally, found generally a good agreement between numerical predictions and measured data, both in terms of leakage and pressure drops across the teeth.
Prediction of the Nonlinear Dynamics of a Multiple Flame Combustor by Coupling the Describing Function Methodology With a Helmholtz Solver
Authors: Cuquel Alexis , Silva Camilo , Nicoud Franck , Durox Daniel , Schuller Thierry
Published: November 2013

This study focuses on the numerical determination of thermo-acoustic instabilities using a combination of the Flame Describing Function (FDF) methodology and a numerical code solving the Helmholtz equation. In this framework, the FDF is defined by a set of Flame Transfer Functions (FTF) that depend on both the frequency and amplitude of acoustic perturbations. The FDF methodology has been recently used in combination with acoustic network methods to examine the nonlinear stability of generic configurations with simplified geometries. Its extension to complex 3D geometries requires the use of numerical tools such as a Helmholtz solver. In the present work, that combination is validated on a multiple injection combustor. The implementation of the FDF methodology in the Helmholtz solver is detailed before examining numerical predictions obtained by the use of an experimentally determined FDF in the Helmholtz solver. The instability frequencies and growth rates are determined for each perturbation level and different nonlinear behaviors are exhibited depending on the combustor geometry. The case of linearly unstable modes reaching limit cycles is first examined. A more complex case involving mode switching is then examined when two unstable modes are present. In this situation, the most unstable mode in the linear regime triggers another unstable mode at a higher perturbation level. These numerical calculations are compared with experimental data and exhibit a good match in terms of amplitude and frequency reached by the limit cycle.
A Review of the Oxford Turbine Research Facility
Authors: Chana Kam , Cardwell Dave , Jones Terry
Published: November 2013

Gas turbine engine efficiency and reliability is generally improved through better understanding and improvements to the design of individual components. The life limiting component of the modern gas turbine is the high pressure (HP) turbine stage due to the arduous environment. Over the last 50 years significant research effort has been focused on advancing blade cooling designs and materials.

Due to practical limitations little fundamental research on the turbine system is performed in the operating gas turbine engine. Consequently different types of experimental approaches have been developed over the last 4 decades to study the flow and in particular the heat transfer and cooling in turbines.

In general the facilities can be divided into continuous running or short duration and cascade or rotating. Over the last 30 years short duration facilities have dominated the research in the study of turbine heat transfer and cooling.

The Oxford Turbine Research Facility (formerly known as the QinetiQ Turbine Test Facility, The Isentropic Light Piston Facility and The Isentropic Light Piston Cascade) is a short duration facility developed and built in the late 1970s and early 1980s for turbine heat transfer and cooling studies.

This paper presents the developments and measurements taken on the facility over the last 35 years, including the type of research that has been conducted and, the current capability of the facility.
Considerations on the Compression System Preliminary Design of a Short Haul Aircraft Propulsion System
Authors: Piscopo Giovanni , Zachos Pavlos K. , Pilidis Pericles
Published: November 2013

The preliminary design of turbomachinery components is strongly affected by the application process. This paper documents a compressor comparative design assessment which was conducted with the intent of to highlight the rationale of proposing a new propulsion system for use on short haul aircraft, similar to the Embraer E-Jet. This study establishes and discusses the compressor figures of merit pertaining to short haul operation and their influence on the desired compression layout.

A computational tool to undertake compressor designs is developed and validated against the NASA E3 published compressor layout. With the aid of this software, a few alternative compressor layouts that meet the established criteria are suggested.

The best candidates are highlighted and further studied in terms of individual design parameters such as temperature rise distribution, number of stages and off-design performance. The figures of merit that dictate particular design choices are highlighted and commented. The most advanced candidate design is found to yield a very respectable performance compared to current production engines of the same class. This work aims at highlighting the process through which a modern compression system is designed at a preliminary stage and the design challenges confronting it.
Estimating Gas Turbine Engine Weight, Costs, and Development Time During the Preliminary Aircraft Engine Design Process
Authors: Byerley Aaron R. , Rolling August J. , Van Treuren Kenneth W.
Published: November 2013

This paper describes the application of a weight and cost-estimating methodology used in an undergraduate aircraft engine design course that is taught in concert with a companion course in airframe design. The two preliminary designs, one for the engine and the other for the airframe, must be integrated as subsystems within a system to satisfy the performance requirements of a given mission as outlined in a single “request for proposals”. In recent years, systems engineering management majors have been added to the design teams to work alongside the aeronautical engineering majors to analyze and report on costs, schedule, and technical risk factors in addition to the operational performance factors that have previously been the sole focus of the course. The teaming of technical management majors and aeronautical engineering majors has been driven by a heightened emphasis on system affordability. The cost-estimating methodology for gas turbine engines uses cycle parameters such as turbine rotor inlet temperature, overall pressure ratio, specific fuel consumption, level of technology, and engine dry weight as inputs. A methodology for estimating dry engine weight was developed which uses engine cycle parameters and fan face diameter as inputs in a volume analog scaling factor which was correlated against historical engine weight data. To tie all of the performance, weight, cost, and development time issues together, the paper presents an “analysis of alternatives” example that considers three different engine cycle alternatives. The design tools presented in this paper will provide a strong foundational understanding of how to systematically weigh and evaluate the important tradeoffs between aircraft turbofan engine performance, cost, schedule, and risk factors. Equipping students with the insight and ability to perform these multidisciplinary trade studies during the preliminary engine design process is this paper’s most important contribution.
Flame Dynamics With Hydrogen Addition at Lean Blowout Limits
Authors: Zhu Shengrong , Acharya Sumanta
Published: November 2013

Lean premixed combustion is widely used in power generation due to the low nitric oxide emissions. Recent interest in syngas requires a better understanding of the role of hydrogen addition on the combustion process. In the present study, the extinction process of hydrogen enriched premixed flames near Lean Blow Out (LBO) in a swirl-stabilized combustor has been examined in both unconfined and confined configurations. High speed images of the flame chemiluminescence are recorded and a proper orthogonal decomposition (POD) procedure is used to extract the dominant flame dynamics during the LBO process. By examining the POD modes, the spectral information and the statistical properties of POD coefficients, the effect of hydrogen addition on the LBO processes are analyzed and described in the paper. Results show that in unconfined flames, the shear layer mode along with flame rotation with local quenching and re-ignition is dominant in the methane-only case. For the open hydrogen enriched flames, the extinction times are longer and are linked to the lower minimum ignition energy for hydrogen that facilitates re-ignition events. In confined methane flames, a conical flame is observed and the POD mode representing the burning in the central recirculation zone appears to be dominant. For the 60% hydrogen enriched flame, a columnar burning pattern is observed and the fluctuation energies are evenly spread across several POD modes making this structure more prone to external disturbances and shorter extinction times.
Improving Pin-Fin Heat Transfer Predictions Using Artificial Neural Networks
Authors: Ostanek Jason K.
Published: November 2013

In much of the public literature on pin-fin heat transfer, Nusselt number is presented as a function of Reynolds number using a power-law correlation. Power-law correlations typically have an accuracy of 20% while the experimental uncertainty of such measurements is typically between 5% and 10%. Additionally, the use of power-law correlations may require many sets of empirical constants to fully characterize heat transfer for different geometrical arrangements. In the present work, artificial neural networks were used to predict heat transfer as a function of streamwise spacing, spanwise spacing, pin-fin height, Reynolds number, and row position. When predicting experimental heat transfer data, the neural network was able to predict 73% of array-averaged heat transfer data to within 10% accuracy while published power-law correlations predicted 48% of the data to within 10% accuracy. Similarly, the neural network predicted 81% of row-averaged data to within 10% accuracy while 52% of the data was predicted to within 10% accuracy using power-law correlations. The present work shows that first-order heat transfer predictions may be simplified by using a single neural network model rather than combining or interpolating between power-law correlations. Furthermore, the neural network may be expanded to include additional pin-fin features of interest such as fillets, duct rotation, pin shape, pin inclination angle, and more making neural networks expandable and adaptable models for predicting pin-fin heat transfer.
Control Architecture Study Focused on Energy Savings of an Aircraft Thermal Management System
Authors: Roberts Rory A. , Decker Daniel D.
Published: November 2013

The next generation of aircraft will face more challenging demands in both electrical and thermal loads. The larger thermal loads reduce the propulsion system efficiency by demanding bleed air from the main engine compressor or imposing a shaft load on the high or low pressure shaft. The approach adopted to power the thermal management system influences the overall fuel burn of the aircraft for a given mission. To assess these demands and to explore conceptual designs for the electrical and thermal management system, a dynamic vehicle level tip-to-tail (T2T) model has been developed. The T2T model captures and quantifies the energy exchanges throughout the aircraft. The following subsystems of the aircraft are simulated in the T2T model: Air vehicle system, propulsion system, adaptive power thermal management system, fuel thermal management system, electrical system and actuator system. This paper presents trade studies of the impact of various approaches in power take-off from the main engine and control strategies. The trade studies identify different control strategies resulting in significant fuel savings for a given mission profile.
An Experimental Validation of Heat Release Rate Fluctuation Measurements in Technically Premixed Flames
Authors: Orawannukul Poravee , Quay Bryan D. , Santavicca Domenic A.
Published: November 2013

Knowledge of the effects of inlet velocity and inlet equivalence ratio fluctuations on the rate of heat release in lean premixed gas turbine combustors is essential for predicting combustor instability characteristics. This information is typically obtained from independent velocity-forced and fuel-forced flame transfer function measurements, where the global chemiluminescence intensity is used as a measure of the flame’s overall rate of heat release. The flame in an actual lean premixed combustor is referred to as a technically premixed flame and is exposed to both velocity and equivalence ratio fluctuations. Under these conditions the chemiluminescence intensity does not provide a reliable measure of the flame’s rate of heat release. The objective of this work is to experimentally assess the validity of a technique for making heat release rate measurements in technically premixed flames based on the linear superposition of fuel-forced and velocity-forced flame transfer function measurements. In the absence of a technique for directly measuring the heat release rate fluctuations in an air-forced technically premixed, the heat release reconstruction is validated indirectly by comparing measured to reconstructed chemiluminescence intensity fluctuations. Results are reported for a range of operating conditions and forcing frequencies which demonstrate the capabilities and limitations of this technique. A variation of this technique, referred to as a reverse reconstruction, is proposed which does not require a measurement of the fuel-forced flame transfer function. The air-forced flame transfer function gain and phase obtained using the reverse reconstruction technique are presented and compared to the results from the direct reconstruction technique.
Reaction Zone Characterization in a Gas Turbine Model Validation Combustor
Authors: Bedick Clinton R. , Weiland Nathan T. , Strakey Peter A.
Published: November 2013

The Enclosed Sydney Swirl Burner (ESSB), a half-scale version of the Sydney Swirl Burner coupled to an optically accessible combustion chamber, was recently constructed at the National Energy Technology Laboratory for the purpose of generating global emissions and model validation data in a configuration relevant to industrial and gas turbine combustion. The ESSB is capable of diffusion flame combustion of CH4/H2/inert fuel mixtures in highly swirling air flow over a bluff body, and can produce a wide variety of flame types and structures for study. Based on stability characteristics and global emissions data, three flames were chosen for reaction zone characterization: a non-swirling 1:1 H2:CH4 flame, a high-swirl 1:1 H2:CH4 flame, and a lifted, V-shaped flame of CH4 with a swirling air flow. Reaction zone characterization is performed via planar OH-PLIF measurements taken at multiple locations within the square cross-section of the ESSB. Mean flame surface locations are described, and maps of flame front probabilities are generated for each of the flames. Measurements indicate quenching in the high strain region in the neck above the bluff body for the non-swirling flame, wall-quenching for the swirling flames, and OH production below the lifted flame that helps sustain the reaction zone. The OH-PLIF data, as well as global emissions and thermal boundary condition measurements for these flames, are freely available for model validation purposes.
High Fidelity Simulation of the Spray Generated by a Realistic Swirling Flow Injector
Authors: Li X. , Soteriou M. C. , Kim W. , Cohen J. M. , Herrmann M. , Ham F. , Kim D. , Le H. , Spyropoulos J. T.
Published: November 2013

Practical aero-engine fuel injection systems are highly complicated, combining complex fuel atomizer and air swirling elements to achieve good fuel-air mixing as well as long residence time in order to enhance both combustion efficiency and stability. While detailed understanding of the multiphase flow processes occurring in a realistic injector has been limited due to the complex geometries and the challenges in near-field measurements, high fidelity, first principles simulation offers, for the first time, the potential for a comprehensive physics-based understanding. In this work, such simulations have been performed to investigate the spray atomization and subsequent droplet transport in a swirling air stream generated by a complex multi-nozzle/swirler combination. A Coupled Level Set and Volume Of Fluid (CLSVOF) approach is used to directly capture the liquid-gas interface and an embedded boundary (EB) method is applied to flexibly handle the complex injector geometry. The ghost fluid (GF) method is also used to facilitate simulations at realistic fuel-air density ratio. Adaptive mesh refinement (AMR) and Lagrangian droplet models are used to efficiently resolve the multi-scale processes. To alleviate the global constraint on the time-step imposed by locally activated AMR near liquid jets, a separate AMR simulation focusing on jet atomization was performed for relatively short physical time and the resulting Lagrangian droplets are coupled into another simulation on a uniform grid at larger time-steps. The high cost simulations were performed at the U.S. Department of Defense high performance computing facilities using over 5000 processors. Experiments at the same flow conditions were conducted at UTRC. The simulation details of flow velocity and vorticity due to the interaction of the fuel jet and swirling air are presented. The velocity magnitude is compared with experimental measurement at two downstream planes. The two-phase spray spreading is compared with experimental images and the flow details are further analyzed to enhance understanding of the complex physics.
A New 1.5-Stage Turbine Wheelspace Hot Gas Ingestion Rig (HGIR): Part II — CFD Modeling and Validation
Authors: Ding Zhongman , Palafox Pepe , Moore Kenneth , Chupp Raymond , Kirtley Kevin
Published: November 2013

Fundamental test data for different rim seal geometries have been obtained from the Hot Gas Ingestion Rig (HGIR), a scaled 1.5-stage turbine rig configured from a current generation heavy duty gas turbine. With well-controlled operating conditions the rig has provided valuable sets of data for CFD tool validation. Part I of this work [1] introduced details on the HGIR design and test data summary from selected rim seal configurations and test conditions. In this study, Part II, CFD simulations were carried out on the baseline test configuration, and different modeling approaches were compared to identify and validate a “reduced-order” CFD methodology, i.e. CFX analyses using the k-ε model with scalable wall function. The results show steady state CFD simulation to be incapable of predicting the ingestion levels observed from rig data. However, unsteady solutions using a two-vane/four-blade sector model including a stator-rotor domain interface showed ingestion over the outer rim seal that was in reasonably good agreement with test data. Good agreement was also obtained on pressure distributions in the circumferential direction. The identified “reduced-order” CFD modeling methodology demonstrated enough sensitivity to differentiate between sealing geometry variations, and thus can be applied to guide rim seal design.
Dosage Compensation via Transposable Element Mediated Rewiring of a Regulatory Network
Authors: Ellison Christopher E. , Bachtrog Doris
Published: November 2013

Getting the Dosage Right

As sex chromosomes evolve, they must compensate for differential gene dosage, especially in non-sex-specific genes. However, owing to the relative rarity of chromosomes that are in the process of becoming sex chromosomes, the ongoing evolutionary processes resulting in dosage compensation are unclear.Ellison and Bachtrog(p.846; see the Perspective byChuong and Feschotte) identified a specific transposable element involved in dosage compensation in males on the evolutionarily new neo-X chromosome ofDrosophila miranda. A particular copy of this transposable element has been inserted at chromatin entry sites on the neo-X chromosome that favorably binds to the male-specific lethal complex, which in turn facilitates the spreading of chromatin silencing on a single chromosome to provide dosage compensation.
What Does Zero Deforestation Mean?
Authors: Brown Sandra , Zarin Daniel
Published: November 2013

Ambiguous definitions and metrics create risks for forest conservation and accountability.
Staphylococcus aureus
Degrades Neutrophil Extracellular Traps to Promote Immune Cell Death
Authors: Thammavongsa Vilasack , Missiakas Dominique M. , Schneewind Olaf
Published: November 2013

Slipping the NET

One spectacular response to bacterial infection is the release of NETs (neutrophil extracellular traps) of DNA from polymorphonuclear leukocytes that immobilize the pathogens and prevent phagocytosis by macrophages.
Staphylococcus aureus
evades NETs by degrading the DNA into deoxyadenosine (dAdo).

Thammavongsa
et al.

(p.
863
) found that dAdo also promotes immune cell death, which appears to ensure the exclusion of macrophages from the center of abscesses within which the bacteria survive.
Failures to Compute
Arguments That Count
Physics, Computing, and Missile Defense, 1949–2012

by Rebecca Slayton

MIT Press, Cambridge, MA, 2013. 337 pp. $35, £24.95. ISBN 9780262019446. Inside Technology.
Authors: Mody Cyrus C. M.
Published: November 2013

Slayton draws on historical documents and interviews to compare how physicists and computer scientists evaluated missile defense systems.
A Nickel Finish Protects Silicon Photoanodes for Water Splitting
Authors: Turner John A.
Published: November 2013

Ultrathin nickel coatings allow silicon to act as the oxygen-generating electrode in the direct formation of hydrogen from water with sunlight.

[Also see Report by

Kenney
et al.

]
Detection of Rickettsia in Rhipicephalus sanguineus Ticks and Ctenocephalides felis Fleas from Southeastern Tunisia by Reverse Line Blot Assay
Authors: Khrouf Fatma , M'Ghirbi Youmna , Znazen Abir , Ben Jemaa Mounir , Hammami Adnene , Bouattour Ali
Published: November 2013

Ticks (
n
= 663) and fleas (
n
= 470) collected from domestic animals from southeastern Tunisia were screened for
Rickettsia
infection using reverse line blot assay. Evidence of spotted fever group
Rickettsia
was obtained. We detected
Rickettsia felis
in fleas,
Rickettsia massiliae
Bar 29 and the
Rickettsia conorii
Israeli spotted fever strain in ticks, and
Rickettsia conorii
subsp.
conorii
and
Rickettsia
spp. in both arthropods. The sensitivity of the adopted technique allowed the identification of a new association between fleas and
R. conorii
subsp.
conorii
species. The presence of these vector-borne
Rickettsia
infections should be considered when diagnosing this disease in humans in Tunisia.
Seven Hours to Adequate Antimicrobial Therapy in Urosepsis Using Isothermal Microcalorimetry
Authors: Braissant Olivier , Müller Georg , Egli Adrian , Widmer Andreas , Frei Reno , Halla Armin , Wirz Dieter , Gasser Thomas C. , Bachmann Alexander , Wagenlehner Florian , Bonkat Gernot
Published: November 2013

Urosepsis can progress toward severe sepsis, septic shock, and, ultimately, death. Rapid antimicrobial susceptibility testing is crucial to decrease mortality and morbidity. This report shows that isothermal microcalorimetry can provide an antibiogram within 7 h with a sensitivity of 95% and specificity of 91% using Vitek-2 system as a reference.
Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Staphylococcus spp. and Enterococcus spp
Authors: Bobenchik April M. , Hindler Janet A. , Giltner Carmen L. , Saeki Sandra , Humphries Romney M.
Published: November 2013

Vitek 2 (bioMérieux, Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility testing system. We compared MIC results obtained by Vitek 2 to those obtained by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method for 134 staphylococcal and 84 enterococcal clinical isolates. Nineteen agents were evaluated, including all those available on Vitek 2 for testing staphylococci and enterococci. The resistance phenotypes tested included methicillin-resistant
Staphylococcus aureus
(MRSA) (
n
= 58),
S. aureus
with inducible clindamycin resistance (ICR) (
n
= 30), trimethoprim-sulfamethoxazole-resistant MRSA (
n
= 10), vancomycin-resistant
Enterococcus
(
n
= 37), high-level gentamicin-resistant
Enterococcus
(
n
= 15), linezolid-resistant
Enterococcus
(
n
= 5), and daptomycin-nonsusceptible
Enterococcus faecalis
(
n
= 6). For the staphylococci, there was 98.9% categorical agreement (CA). There was one very major error (VME) for gentamicin in a
Staphylococcus hominis
isolate, six VMEs for inducible clindamycin in
S. aureus
isolates, and two major errors (ME) for daptomycin in an
S. aureus
and a
Staphylococcus epidermidis
isolate. For enterococci, there was 97.3% CA. Two VMEs were observed for daptomycin in isolates of
E. faecalis
and 2 ME, 1 for high-level gentamicin resistance and 1 for nitrofurantoin, in
E. faecium
isolates. Overall, there was 98.3% CA and 99% essential agreement for the testing of staphylococci and enterococci by the Vitek 2. With the exception of detecting ICR in
S. aureus
, Vitek 2 performed reliably for antimicrobial susceptibility testing of staphylococci and enterococci.
Comparison of Simplexa Universal Direct PCR with Cytotoxicity Assay for Diagnosis of Clostridium difficile Infection: Performance, Cost, and Correlation with Disease
Authors: Landry Marie L. , Ferguson David , Topal Jeffrey
Published: November 2013

Simplexa
Clostridium difficile
universal direct PCR, a real-time PCR assay for the detection of the
C. difficile
toxin B (
tcdB
) gene using the 3M integrated cycler, was compared with a two-step algorithm which includes the C. Diff Chek-60 glutamate dehydrogenase (GDH) antigen assay followed by cytotoxin neutralization. Three hundred forty-two liquid or semisolid stools submitted for diagnostic
C. difficile
testing, 171 GDH antigen positive and 171 GDH antigen negative, were selected for the study. All samples were tested by the C. Diff Chek-60 GDH antigen assay, cytotoxin neutralization, and Simplexa direct PCR. Of 171 GDH-positive samples, 4 were excluded (from patients on therapy or from whom duplicate samples were obtained) and 88 were determined to be true positives for toxigenic
C. difficile
. Of the 88, 67 (76.1%) were positive by the two-step method and 86 (97.7%) were positive by PCR. Seventy-nine were positive by the GDH antigen assay only. Of 171 GDH antigen-negative samples, none were positive by PCR. One antigen-negative sample positive by the cytotoxin assay only was deemed a false positive based on chart review. Simplexa
C. difficile
universal direct PCR was significantly more sensitive for detecting toxigenic
C. difficile
bacteria than cytotoxin neutralization (
P
= 0.0002). However, most PCR-positive/cytotoxin-negative patients did not have clear
C. difficile
disease. The estimated cost avoidance provided by a more rapid molecular diagnosis was outweighed by the cost of isolating and treating PCR-positive/cytotoxin-negative patients. The costs, clinical consequences, and impact on nosocomial transmission of treating and/or isolating patients positive for toxigenic
C. difficile
by PCR but negative for
in vivo
toxin production merit further study.
Novel H7N9 Influenza Virus Shows Low Infectious Dose, High Growth Rate, and Efficient Contact Transmission in the Guinea Pig Model
Authors: Gabbard Jon D. , Dlugolenski Daniel , Van Riel Debby , Marshall Nicolle , Galloway Summer E. , Howerth Elizabeth W. , Campbell Patricia J. , Jones Cheryl , Johnson Scott , Byrd-Leotis Lauren , Steinhauer David A. , Kuiken Thijs , Tompkins S. Mark , Tripp Ralph , Lowen Anice C. , Steel John
Published: November 2013

The zoonotic outbreak of H7N9 subtype avian influenza virus that occurred in eastern China in the spring of 2013 resulted in 135 confirmed human cases, 44 of which were lethal. Sequencing of the viral genome revealed a number of molecular signatures associated with virulence or transmission in mammals. We report here that, in the guinea pig model, a human isolate of novel H7N9 influenza virus, A/Anhui/1/2013 (An/13), is highly dissimilar to an H7N1 avian isolate and instead behaves similarly to a human seasonal strain in several respects. An/13 was found to have a low 50% infectious dose, grow to high titers in the upper respiratory tract, and transmit efficiently among cocaged guinea pigs. The pH of fusion of the hemagglutinin (HA) and the binding of virus to fixed guinea pig tissues were also examined. The An/13 HA displayed a relatively elevated pH of fusion characteristic of many avian strains, and An/13 resembled avian viruses in terms of attachment to tissues. One important difference was seen between An/13 and both the H3N2 human and the H7N1 avian viruses: when inoculated intranasally at a high dose, only the An/13 virus led to productive infection of the lower respiratory tract of guinea pigs. In sum, An/13 was found to retain fusion and attachment properties of an avian influenza virus but displayed robust growth and contact transmission in the guinea pig model atypical of avian strains and indicative of mammalian adaptation.
Ranibizumab in choroidal neovascularisation associated with ocular sarcoidosis
Authors: Konidaris Vasileios Efstathios , Empeslidis Theodoros
Published: November 2013

An 81-year-old Caucasian man with a history of chronic bilateral panuveitis associated with sarcoidosis presented with visual acuity 1.0 LogMAR in the right and 0.5 LogMAR in the left eye. Following fluoroscein angiogram bilateral choroidal neovascular membrane was established. Treatment was initiated with a course of 3 monthly intravitreal injections of ranibizumab 0.5 mg in 0.05 mL bilaterally; oral prednisolone 30 mg/day on tapering doses controlled the ocular inflammation prior to the treatment with intravitreal injections. An additional two intravitreal ranibizumab injections were administered in the right eye. Fibrotic tissue in the posterior pole bilaterally was present on funduscopy following ranibizumab treatment. Visual acuity was LogMAR 1.6 in the right and 1.0 LogMAR in the left eye in 1 year follow-up. This case report summarises the issues of choroidal neovascularisation as a complication secondary to panuveitis associated with sarcoidosis and highlights the treatment of this complication with antivascular endothelial growth factor agents.
Small cell lung cancer presenting with a left iliac fossa mass
Authors: Jethwa Hannah , Savage Louis
Published: November 2013

We report a 59-year-old lifelong smoker with severe chronic obstructive pulmonary disease who presented with an acute onset 3-day history of left iliac fossa pain and abdominal distension. Clinical examination revealed a palpable mass in the left iliac fossa. The differential diagnosis was that of a diverticular abscess or colonic tumour. She subsequently underwent a CT scan which showed extensive metastatic liver disease from a primary lung tumour, with hepatomegaly abutting the anterior abdominal wall in the left iliac fossa.
Are familial factors underlying the association between socioeconomic position and prescription medicine? A register-based study on Danish twins
Authors: Madsen Mia , Andersen Per Kragh , Gerster Mette , Andersen Anne-Marie Nybo , Osler Merete , Christensen Kaare
Published: November 2013

Objectives

Although well established, the association between socioeconomic position and health and health behaviour is not clearly understood, and it has been speculated that familial factors, for example, dispositional factors or exposures in the rearing environment, may be underlying the association. The objective was to compare prescription fillings within twin pairs who are partly or fully genetically identical and share childhood exposures.

Design

Twin cohort study.

Setting

Denmark.

Participants

Data from the Danish Twin Registry were linked to registers in Statistics Denmark and the Danish Registry of Medicinal Product statistics. A total of 8582 monozygotic (MZ) and 15 788 dizygotic same sex (DZSS) twins were included.

Outcome measures

Number of prescription fillings during follow-up (1995–2005) was analysed according to education and income. Results of unpaired and intrapair analyses were compared.

Results

An inverse social gradient in filling of prescriptions for all-purpose and system-specific drugs was observed in the unpaired analyses. In the intrapair analyses, associations were attenuated some in DZSS and more in MZ twins. Filling of drugs targeting the nervous system was still strongly associated with income in the intrapair analyses.

Conclusions

Familial factors seem to account for part of the observed social inequality in filling of prescription medicine.
Active buildings: modelling physical activity and movement in office buildings. An observational study protocol
Authors: Smith Lee , Ucci Marcella , Marmot Alexi , Spinney Richard , Laskowski Marek , Sawyer Alexia , Konstantatou Marina , Hamer Mark , Ambler Gareth , Wardle Jane , Fisher Abigail
Published: November 2013

Introduction

Health benefits of regular participation in physical activity are well documented but population levels are low. Office layout, and in particular the number and location of office building destinations (eg, print and meeting rooms), may influence both walking time and characteristics of sitting time. No research to date has focused on the role that the layout of the indoor office environment plays in facilitating or inhibiting step counts and characteristics of sitting time. The primary aim of this study was to investigate associations between office layout and physical activity, as well as sitting time using objective measures.

Methods and analysis

Active buildings is a unique collaboration between public health, built environment and computer science researchers. The study involves objective monitoring complemented by a larger questionnaire arm. UK office buildings will be selected based on a variety of features, including office floor area and number of occupants. Questionnaires will include items on standard demographics, well-being, physical activity behaviour and putative socioecological correlates of workplace physical activity. Based on survey responses, approximately 30 participants will be recruited from each building into the objective monitoring arm. Participants will wear accelerometers (to monitor physical activity and sitting inside and outside the office) and a novel tracking device will be placed in the office (to record participant location) for five consecutive days. Data will be analysed using regression analyses, as well as novel agent-based modelling techniques.

Ethics and dissemination

The results of this study will be disseminated through peer-reviewed publications and scientific presentations. Ethical approval was obtained through the University College London Research Ethics Committee (Reference number 4400/001).
Minimal patient handling: a faculty of prehospital care consensus statement
Authors: Moss R , Porter K , Greaves I ,   On behalf of the consensus group
Published: November 2013

This paper outlines the emerging best practice when packaging a prehospital trauma patient while providing spinal immobilisation. The best practice described is based on the recommendations of a consensus meeting held by the Faculty of Pre-Hospital Care, Royal College of Surgeons of Edinburgh, in the West Midlands in April 2012, where the opinion of experienced practitioners from across the prehospital and emergency care community considered the currently available evidence and reviewed current clinical practice. Initial consensus points were then subject to further review and dialogue with stakeholders from the initial meeting. The recommendations drawn from the meeting and subsequent dialogue represent a ‘general agreement’ to the principles and practices described in the paper. The recommendations will provide guidance for clinical practice and governance alongside other consensus statements from the Faculty of Pre-Hospital Care that seek to address prehospital spinal immobilisation and pelvic immobilisation.
Socioeconomic inequalities in all-cause mortality in the Czech Republic, Russia, Poland and Lithuania in the 2000s: findings from the HAPIEE Study
Authors: Vandenheede Hadewijch , Vikhireva Olga , Pikhart Hynek , Kubinova Ruzena , Malyutina Sofia , Pajak Andrzej , Tamosiunas Abdonas , Peasey Anne , Simonova Galina , Topor-Madry Roman , Marmot Michael , Bobak Martin
Published: November 2013

Background

Relatively large socioeconomic inequalities in health and mortality have been observed in Central and Eastern Europe (CEE) and the former Soviet Union (FSU). Yet comparative data are sparse and virtually all studies include only education. The aim of this study is to quantify and compare socioeconomic inequalities in all-cause mortality during the 2000s in urban population samples from four CEE/FSU countries, by three different measures of socioeconomic position (SEP) (education, difficulty buying food and household amenities), reflecting different aspects of SEP.

Methods

Data from the prospective population-based HAPIEE (Health, Alcohol, and Psychosocial factors in Eastern Europe) study were used. The baseline survey (2002–2005) included 16 812 men and 19 180 women aged 45–69 years in Novosibirsk (Russia), Krakow (Poland), Kaunas (Lithuania) and seven Czech towns. Deaths in the cohorts were identified through mortality registers. Data were analysed by direct standardisation and Cox regression, quantifying absolute and relative SEP differences.

Results

Mortality inequalities by the three SEP indicators were observed in all samples. The magnitude of inequalities varied according to gender, country and SEP measure. As expected, given the high mortality rates in Russian men, largest absolute inequalities were found among Russian men (educational slope index of inequality was 19.4 per 1000 person-years). Largest relative inequalities were observed in Czech men and Lithuanian subjects. Disadvantage by all three SEP measures remained strongly associated with increased mortality after adjusting for the other SEP indicators.

Conclusions

The results emphasise the importance of all SEP measures for understanding mortality inequalities in CEE/FSU.