bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonalcoholic fatty liver disease: The hepatic metabolic syndrome
Authors: Page, ACNP‐BC Jeni
Published: April 2012

Abstract  Purpose: To examine a case of nonalcoholic fatty liver disease (NAFLD) and review the incidence, pathophysiology, appropriate diagnostic procedures and imaging, clinical considerations, and treatment options.

Data sources: Findings from the history, physical examination, and diagnostic testing of a 39‐year‐old man with elevated liver enzymes presenting to the hepatology clinic; a search of evidence‐based literature in the PubMed and CINAHL database with the terms “fatty liver,”“nonalcoholic fatty liver disease,” and “nonalcoholic steatohepatitis.”

Conclusions: NAFLD is the deposition of fat in the liver that can progress to nonalcoholic steatohepatitis, resulting in fibrosis and cirrhosis. The exact pathophysiology is unknown, but risk factors can include those criteria associated with metabolic syndrome. NAFLD is a diagnosis of exclusion and can lead to serious health consequences if it is not identified and interventions are not implemented promptly. Treatment options remain limited but currently focus on weight loss, exercise, and diet.

Implication for practice: The clinician must include the spectrum of NAFLD in the differential diagnosis for any patient with elevated liver enzymes. The key actions for diagnosing NAFLD are identifying risk factors and ordering appropriate testing for confirmation. These considerations will lead to early diagnosis and implementation of treatment interventions.
Clarifying, affirming, and preserving the nurse in nurse practitioner education and practice
Authors: Brykczynski Karen
Published: April 2012

Purpose: This work responds to the need for maintaining an ethic of care in the face of increased demands for cost effectiveness and efficiency. Findings are presented from a qualitative study describing how nurse practitioner (NP) faculty teach NP students about holistic nursing dimensions of NP practice.

Data resources: Data collection consisted of face to face or telephone interviews with 24 experienced NP faculty members teaching in 22 NP programs across the country. Data were analyzed using the interpretive phenomenological approach. Aspects of scientific merit were addressed through reviewing transcripts for accuracy, consensual validation sessions, and member checking.

Conclusions: The most common approaches used for teaching holistic nursing dimensions of NP practice were role modeling and sharing narratives of actual cases. Other approaches included: incorporation of holistic complementary diagnoses along with medical diagnoses into assessments, use of case scenarios and standardized patients, a rite of passage ceremony, and an entire narrative curriculum.

Implications for practice: NP faculty advocate incorporating a holistic mind‐body‐spirit perspective into assessment and intervention and broadening the diagnostic process to include complementary components of nursing and medicine. Findings have implications for teaching/learning, curriculum planning, and evaluation as NP programs transition from the master's to the doctoral level.
Examining the benefit of vaccinating adults against pertussis
Authors: Olyarchuk Lizanne D. , Willoughby Deborah , Davis Stephanie C. , Newsom Stacey A.
Published: April 2012

Purpose: To examine recent evidence concerning the health benefits and cost effectiveness of replacing a single dose of adult tetanus/diphtheria vaccine with a single dose of tetanus/diphtheria/pertussis (TDaP).

Methods: A review of the literature was conducted utilizing the databases CINAHL and Medline with the keywords pertussis, adult immunization, vaccination, TDaP, DTaP, and healthcare workers.

Conclusions: Recent outbreaks of pertussis have shown that preventing such outbreaks through immunization of adults with a single TDaP vaccine is a cost‐effective measure. These studies focused on hospitals and universities where air‐borne diseases are easily spread. Four hospital studies that examined the financial cost of investigating and treating a pertussis outbreak were reviewed. Results presented offer strong evidence to support vaccinating adults with TDaP at their next scheduled immunization or sooner if they are frequently exposed to populations vulnerable to pertussis.

Implications for practice: Financially, investigating a single case of pertussis can cost hospitals hundreds of thousands of dollars. This is related to the time and expense of determining who was exposed and the provision of preventive treatment for those exposed. Preventing unnecessary illness and potential mortality, especially among not yet immunized infants, provides a strong argument for administration of the TDaP vaccine. Healthcare providers should educate adults about the availability and advantages of TDaP immunization and encourage them to be immunized with TDaP.
Response interference between functional and structural object‐related actions is increased in patients with ideomotor apraxia
Authors: Jax Steven A. , Buxbaum Laurel J.
Published: April 2012

We report data from two left hemisphere stroke patients with moderate‐to‐severe ideomotor apraxia who exhibited deficits in positioning their hands to use ‘conflict’ objects (objects grasped and used with different hand postures) relative to controls and patients with mild apraxia. These novel data support the claim that actions to common objects are subject to interference between multiple responses, and suggest that errors in apraxia may be attributed to deficient resolution of competition between appropriate and inappropriate actions.
Wealth effect and dental care utilization in the United States
Authors: Manski Richard J. , Moeller John F. , Chen Haiyan , St. Clair Patricia A. , Schimmel Jody , Pepper John V.
Published: April 2012

Objective: The purpose of this article is to examine the relationship of wealth and income and the relative impact of each on dental utilization in a population of older Americans, using data from the Health and Retirement Study (HRS).

Methods: Data from the HRS were analyzed for US individuals aged 51 years and older during the 2008 wave of the HRS. The primary focus of the analysis is the relationship between wealth, income, and dental utilization. We estimate a multivariable model of dental use controlling for wealth, income, and other potentially confounding covariates.

Results: We find that both wealth and income each have a strong and independent positive effect on dental care use of older Americans (P < 0.05). A test of the interaction between income and wealth in our model failed to show that the impact on dental care utilization as wealth increases depends on a person's income level or, alternatively, that the impact on dental use as income increases depends on a person's household wealth status (P > 0.05).

Conclusions: Relative to those living in the wealthiest US households, the likelihood of utilizing dental care appears to decrease with a decline in wealth. The likelihood of utilizing dental care also appears to decrease with a decline in income as well.
Antidiabetic and antihypertensive effect of a polyphenol‐rich fraction of Thymelaea hirsuta L. in a model of neonatal streptozotocin‐diabetic and NG‐nitro‐l‐arginine methyl ester‐hypertensive rats
Authors: BNOUHAM Mohamed , BENALLA Wafaa , BELLAHCEN Said , HAKKOU Zineb , ZIYYAT Abderrahim , MEKHFI Hassane , AZIZ Mohammed , LEGSSYER Abdelkhaleq
Published: April 2012

Background:  The present study examined the effect of the polyphenol‐rich fraction from Thymelaea hirsuta (PRF‐Th) in a rat model of streptozotocin (STZ)‐diabetes and nitric oxide (NO)‐deficient hypertension.

Methods:  Diabetes was induced by a single dose of STZ (90 mg/kg, i.p.). To induce NO‐deficient hypertension, rats were treated with the NO synthase inhibitor NG‐nitro‐l‐arginine methyl ester; l‐NAME; 30 mg/kg per day, p.o. for 3 weeks. The effects of 21 days treatment with 80 mg/kg per day PRF‐Th in the drinking water were evaluated in diabetic–hypertensive (DH) rats. In all groups (n = 6 in each), glycemia and systolic blood pressure were determined weekly. At the end of the experiment, hepatic glycogen was determined.

Results:  Blood glucose levels decreased gradually from baseline until the end of the experiment in untreated DH rats (from 1.92 ± 0.09 to 1.3 ± 0.1 g/L; P < 0.05). Administration of PRF‐Th concomitantly with l‐NAME prevented the blood pressure increase in rats. After 21 days, blood pressure in PRF‐Th + l‐NAME‐ and l‐NAME‐treated rats was 132 ± 1 and 157 ± 1 mmHg, respectively (P < 0.001). Administration of 2 mL/kg per day PRF‐Th to DH rats significantly increased hepatic glycogen levels compared with levels in untreated DH rats (13.65 ± 1.84 vs 6.34 ± 0.75 mg/g tissue, respectively; P < 0.01). Moreover, PRF‐Th significantly reduced the amount of glucose absorbed in in situ perfused jejunum segments compared with control (by 33.6%; P < 0.001). This effect of PRF‐Th was comparable with that of acarbose, an α‐glucosidase inhibitor.

Conclusions:  The findings of the present study indicate that T. hirsuta has antidiabetic and antihypertensive activity in STZ‐diabetic, NO‐deficient hypertensive rats. This effect seems to be due to its rich polyphenol content. Therefore, T. hirsuta may be useful as a food supplement for the prevention of type 2 diabetes and hypertension.
Stromal Cell‐Derived Factor 1α Induces Accumulation of Intraveneously Administered Marrow‐Derived Stromal Cells in the Partially Obstructed Rat Bladder
Authors: SANO Hiroshi , MITSUI Takahiko , KANNO Yukiko , MORIYA Kimihiko , TANAKA Hiroshi , KITTA Takeya , NONOMURA Katsuya
Published: April 2012

Objectives: We investigated the time course of the stromal cell‐derived factor 1α (SDF1α) expression and behavior of intravenously administered bone marrow‐derived stromal (BMS) cells in the urinary bladder of partial bladder outlet obstruction (PBOO) rats.

Methods: Study 1: Recombinant SDF1α or saline was directly injected into the bladder wall of female rats followed by intravenous administration of BMS cells isolated from green fluorescent protein (GFP) transgenic rats. The bladder was examined with immunohistochemistry to determine whether SDF1α would enhance migration of BMS cells to the bladder. Study 2: Following surgery of PBOO or sham in female rats, bladders were removed on days 1–14, and expression of hypoxia inducible factor 1α (HIF1α) and SDF1α were examined with real‐time polymerase chain reaction (PCR) to determine if PBOO preferentially increased their expression. Study 3: Female rats underwent PBOO or sham surgery followed by intravenous administration of GFP‐positive BMS cells. Bladders were examined with immunohistochemistry on days 1–14 to determine whether BMS cells preferentially accumulated in the bladder.

Results: BMS cells were accumulated in the injection site of SDF1α but not saline in the bladder. SDF1α and HIF1α increased at day 1 after PBOO compared to sham. More BMS cells accumulated in the bladder of PBOO on day 1, and some BMS cells expressed smooth muscle phenotypes by day 14.

Conclusion: SDF1α induced with ischemia/hypoxia due to PBOO is implicated in the accumulation of BMS cells in the bladder and regeneration of the bladder for PBOO.
Analysis of Travel Times and CO2 Emissions in Time‐Dependent Vehicle Routing
Authors: Jabali O. , VanWoensel T. , de Kok A.G.
Published: April 2012

Due to the growing concern over environmental issues, regardless of whether companies are going to voluntarily incorporate green policies in practice, or will be forced to do so in the context of new legislation, change is foreseen in the future of transportation management. Assigning and scheduling vehicles to service a pre‐determined set of clients is a common distribution problem. Accounting for time‐dependent travel times between customers, we present a model that considers travel time, fuel, and CO2 emissions costs. Specifically, we propose a framework for modeling CO2 emissions in a time‐dependent vehicle routing context. The model is solved via a tabu search procedure. As the amount of CO2 emissions is correlated with vehicle speed, our model considers limiting vehicle speed as part of the optimization. The emissions per kilometer as a function of speed are minimized at a unique speed. However, we show that in a time‐dependent environment this speed is sub‐optimal in terms of total emissions. This occurs if vehicles are able to avoid running into congestion periods where they incur high emissions. Clearly, considering this trade‐off in the vehicle routing problem has great practical potential. In the same line, we construct bounds on the total amount of emissions to be saved by making use of the standard VRP solutions. As fuel consumption is correlated with CO2 emissions, we show that reducing emissions leads to reducing costs. For a number of experimental settings, we show that limiting vehicle speeds is desired from a total cost perspective. This namely stems from the trade‐off between fuel and travel time costs.
A Multi‐Supplier Sourcing Problem with a Preference Ordering of Suppliers
Authors: Honhon Dorothée , Gaur Vishal , Seshadri Sridhar
Published: April 2012

We study a sourcing problem faced by a firm that seeks to procure a product or a component from a pool of alternative suppliers. The firm has a preference ordering of the suppliers based on factors such as their past performance, quality, service, geographical location, and financial strength, which are commonly included in a supplier scorecard system. Thus, the firm first uses available inventory from supplier 1, if any, then supplier 2, if any, and so on. The suppliers differ in costs and prices. The buyer firm seeks to determine which suppliers to purchase from and in what quantities to maximize its total expected profit subject to the preference ordering constraint. We present the optimal solution to this problem, and show that it has a portfolio structure. It consists of a sub‐set of suppliers that are ordered by their underage and overage costs. This portfolio achieves a substantial profit gain compared to sourcing from a unique supplier. We present an efficient algorithm to compute the optimal solution. Our model applies to component sourcing problems in manufacturing, merchandizing problems in retailing, and capacity reservation problems in services.
Gray Markets, A Product of Demand Uncertainty and Excess Inventory
Authors: Dasu Sriram , Ahmadi Reza , Carr Scott M.
Published: April 2012

Diverting large quantities of goods from authorized distribution channels to unauthorized or “gray market” channels, albeit legal, significantly affects both firms and consumers due to effects on price, revenue, service and warranty availability, and product availability. In this paper we consider mechanisms by which the uncertainty surrounding inventory ordering decisions drives gray markets. We start with a minimal stochastic supply chain model composed of a producer and a retailer; then we restructure the model to add a distributor whereby the distributor and authorized retailer have the option of diverting inventory to a gray market. Our analysis sheds light on three issues: impacts of diversion on the various supply chain participants, strategies producers could use to combat or exploit gray markets, and important considerations for authorized retailers trying to set optimal order quantities in the presence of a gray market. Our analysis yields new insights into the behavior and impact of gray markets, which can inform management strategies and policies for confronting them.
Serum D‐Lactate Concentrations in Cats with Gastrointestinal Disease
Authors: Packer R.A. , Moore G.E. , Chang C.‐Y. , Zello G.A. , Abeysekara S. , Naylor J.M. , Steiner J.M. , Suchodolski J.S. , O'Brien D.P.
Published: April 2012

Background

Increased D‐lactate concentrations cause neurological signs in humans with gastrointestinal disease.

Hypothesis/Objectives

To determine if serum D‐lactate concentrations are increased in cats with gastrointestinal disease compared to healthy controls, and if concentrations correlate with specific neurological or gastrointestinal abnormalities.

Animals

Systematically selected serum samples submitted to the Gastrointestinal Laboratory at Texas A&M University from 100 cats with clinical signs of gastrointestinal disease and abnormal gastrointestinal function tests, and 30 healthy cats.

Methods

Case‐control study in which serum D‐ and L‐lactate concentrations and retrospective data on clinical signs were compared between 30 healthy cats and 100 cats with gastrointestinal disease. Association of D‐lactate concentration with tests of GI dysfunction and neurological signs was evaluated by multivariate linear and logistic regression analyses, respectively.

Results

All 100 cats had a history of abnormal gastrointestinal signs and abnormal gastrointestinal function test results. Thirty‐one cats had definitive or subjective neurological abnormalities. D‐lactate concentrations of cats with gastrointestinal disease (median 0.36, range 0.04–8.33 mmol/L) were significantly higher than those in healthy controls (median 0.22, range 0.04–0.87 mmol/L; P = .022). L‐lactate concentrations were not significantly different between the 2 groups of cats with gastrointestinal disease and healthy controls. D‐lactate concentrations were not significantly associated with fPLI, fTLI, cobalamin, folate, or neurological abnormalities (P > .05).

Conclusions and Clinical Importance

D‐lactate concentrations can be increased in cats with gastrointestinal disease. These findings warrant additional investigations into the role of intestinal microbiota derangements in cats with gastrointestinal disease, and the association of D‐lactate and neurological abnormalities.
Investigation of the Coal Gasification Process Under Various Operating Conditions Inside a Two-Stage Entrained Flow Gasifier
Authors: Silaen Armin , Wang Ting
Published: April 2012

Numerical simulations of the coal gasification process inside a generic 2-stage entrained-flow gasifier fed with Indonesian coal at approximately 2000 metric ton/day are carried out. The 3D Navier–Stokes equations and eight species transport equations are solved with three heterogeneous global reactions, three homogeneous reactions, and two-step thermal cracking equation of volatiles. The chemical percolation devolatilization (CPD) model is used for the devolatilization process. This study is conducted to investigate the effects of different operation parameters on the gasification process including coal mixture (dry versus slurry), oxidant (oxygen-blown versus air-blown), and different coal distribution between two stages. In the two-stage coal-slurry feed operation, the dominant reactions are intense char combustion in the first stage and enhanced gasification reactions in the second stage. The gas temperature in the first stage for the dry-fed case is about 800 K higher than the slurry-fed case. This calls for attention of additional refractory maintenance in the dry-fed case. One-stage operation yields higher H2, CO and CH4 combined than if a two-stage operation is used, but with a lower syngas heating value. The higher heating value (HHV) of syngas for the one-stage operation is 7.68 MJ/kg, compared with 8.24 MJ/kg for two-stage operation with 75%–25% fuel distribution and 9.03 MJ/kg for two-stage operation with 50%–50% fuel distribution. Carbon conversion efficiency of the air-blown case is 77.3%, which is much lower than that of the oxygen-blown case (99.4%). The syngas heating value for the air-blown case is 4.40 MJ/kg, which is almost half of the heating value of the oxygen-blown case (8.24 MJ/kg).
An Experimental Study on Micro Proton Exchange Membrane Fuel Cell
Authors: Chen Chiun-Hsun , Chen Tang-Yuan , Cheng Chih-Wei , Peng Rong-Guie
Published: April 2012

This study fabricates a micro proton exchange membrane fuel cell (PEMFC) using micro electro mechanical systems (MEMS) technology. The active area of the membrane is 2 cm × 2 cm (4 cm2). The study is divided into two categories: [(1) the parametric experimental investigation, and (2) the durability test. This work is an attempt to find out how several parameters, including reheat temperature, the material of the current collector plates, the open ratio, and different cathode gases affect micro PEFMC performance. According to the experimental results obtained, both the conducting area and the material of the current collector plates exert great influences on the performance of the micro PEMFC, especially in the conducting area. The cell’s performance is finite when the gas reheat temperature is increased. The results show that the cell performance is better for an open ratio of 75% as compared to ratios of 50% and 67%. The concentration polarization is improved by increasing the air flow rate at high current densities, and if the GDL diffusive capability in the latter cell could be promoted, the differences between these two cells’ performances would be reduced. Furthermore, the performance at an operating voltage of 0.6 V was the most stable one among the four cases tested, and the performance deviation at a fixed operating voltage of 0.4 V was less than ±2.2%.
Increase in Availability of Solid Oxide Fuel Cells by Means of Parallel Connection of Cells
Authors: Stagge Hanno , Doerrer Lars , Benger Ralf , Hans-Peter Beck
Published: April 2012

Fuel cells consist of single cells that are connected in series to form a stack. This increases output voltage and therefore decreases current-dependent power losses, but the electric current of the stack has to flow through each single cell. In case of an increase of resistance or a failure of just one single cell the whole stack is affected. The failure tolerance of a parallel connection is higher. The serial and parallel connection of single solid oxide fuel cells (SOFC) is compared under the aspects of failure probability, power drop and stress on the single cells. With both a highly linearized and a complex SOFC model simulations have been accomplished of the connection of two single cells in parallel and in serial configuration. Additionally different connection concepts of 16 single cells were examined. Finally, an outlook on different other source or storage technologies for electric energy like batteries and photovoltaic cells is given.
Multiscale Electrical Contact Resistance Between Gas Diffusion Layer and Bipolar Plate in Proton Exchange Membrane Fuel Cells
Authors: Yoo Sunghun , Hoon Jang Yong
Published: April 2012

The contact resistance between gas diffusion layer and bipolar plate in a fuel cell stack is calculated through multiscale contact analysis, which deals with rough surfaces dependent on scales. The rough surface according to scale shows that the surface parameters vary with scale, leading to inaccurate contact resistance. A numerical model is established to reflect the contact interaction of carbon graphite fiber in the contact interface. Two separate analyses are performed, static analysis to determine the contact area and electrical conduction analysis to calculate the electrical contact resistance. Results show that the contact area decreases and the corresponding contact resistance increases as the scale decreases. To accurately estimate the contact resistance, an asymptotic contact resistance according to scale variation is predicted using error analysis. The computed contact resistance is validated via comparison with previously reported values.
Investigation of Bubble and Fluid Flow Patterns Within a Column Photobioreactor
Authors: Mortuza S. M. , Gent Stephen P. , Kommareddy Anil , Anderson Gary A.
Published: April 2012

This research study investigates bubble and liquid circulation patterns in a vertical column photobioreactor (PBR) both experimentally as well as computationally using computational fluid dynamics (CFD). Dispersed gas-liquid flow in the rectangular bubble column PBR are modeled using Eulerian-Lagrangian approach. A low Reynolds number k-epsilon CFD model is used to describe the flow pattern near the wall. A flat surface bubble column PBR is used to achieve sufficient light penetration into the system. Bubble size distribution measurements were completed using a high-speed digital camera. Operating parameters, bubble flow patterns, and internal hydrodynamics of a bubble column reactor were studied, and the numerical simulations presented for the hydrodynamics in a bubble column PBR account for bubble phenomena that have not been sufficiently accounted for in previous research. Bubble size and shape affect the hydrodynamics as does bubble interaction with other bubbles (multiple bubbles in a flow versus single bubbles and wall effects on bubble(s) that are not symmetrical or bubbles not centered on the reactor cross-section). Understanding the bubble movement patterns will aid in predicting other design parameters like mass transfer (bubble to liquid and liquid to bubble), heat transfer (within the PBR and between the PBR and environment surrounding the PBR), and interaction forces inside the PBR. The computational results are validated with experimental data and from current literature.
Analysis of Performance and Thermal-Fluid Characteristics in a Planar Type Solid Oxide Fuel Cell
Authors: Ahn Hyojung
Published: April 2012

This work studied internal loss factors (flow rate, pressure, partial pressure, voltage, current, temperature, etc.) in a unit cell and stack of solid oxide fuel cells (SOFC) with different separator materials, operation temperature and types of gas supply channels by employing computational fluid dynamics (CFD). A steel separator (AISI430) was superior to a ceramic plate (LaCrO3) in an aspect of thermal stress due to high thermal conductivity but inferior at average current density and fuel utilization rate. As initial temperature at the cell inlet was lowered from 950 °C to 650 °C per each pattern of gas flow (co-flow and counter-flow), useful data were acquired to analyze a performance drop. I-V curves at 650 °C and 900 °C, which involved various parameters as separator materials and directions of gas supply, compared performance characterization between low and high temperature SOFC and also implied the most effective combination.
Development of a Proof-of-Concept Proton Exchange Membrane Fuel Cell Powered Scooter
Authors: Diloyan Georgiy , Breziner Luis , Hutapea Parsaoran
Published: April 2012

The objective of this project is to develop a proton exchange membrane (PEM) fuel cell powered scooter with a designed digital controller to regulate the air supply to PEM fuel cell stack. A 500-Watt (W) electric power train was chosen as a platform for the scooter. Two 300 W PEM fuel cell systems, each containing 63 cells, were used to charge 48-Volt batteries that powered an electric motor. The energy carrier (hydrogen) was stored in two metal hydride tanks, each one containing 85 gs of hydrogen pressurized to 250 psig. The output hydrogen pressure from each tank was maintained at 5.8 psi by a two-stage pressure regulator, and then delivered to each fuel cell stack. To regulate the voltage of each PEM fuel cell under different load conditions, two step down DC/DC converters were used. These converters were connected in series to power the motor controller and charge the batteries. The batteries then supplied power to the 500 W brushless motor mounted to the hub of the rear wheel to save space. After all modifications were completed, most of the parts of the scooter stayed the same except for the panel under the seat—where larger space is needed for accommodating the hydrogen tanks. The weight of the scooter did not change significantly, because the weight of the hydrogen tanks (6.5 kg each) and fuel cell stacks (1.7 kg each) was partially compensated by replacing the batteries from the old ones that weighed 17.5 kg to new ones that weighed 9 kg.
Numerical Simulation of Cavity Shedding from a Three-Dimensional Twisted Hydrofoil and Induced Pressure Fluctuation by Large-Eddy Simulation
Authors: Luo Xianwu , Ji Bin , Peng Xiaoxing , Xu Hongyuan , Nishi Michihiro
Published: April 2012

Simulation of cavity shedding around a three-dimensional twisted hydrofoil has been conducted by large eddy simulation coupling with a mass transfer cavitation model based on the Rayleigh-Plesset equation. From comparison of the numerical results with experimental observations, e.g., cavity shedding evolution, it is validated that the unsteady cavitating flow around a twisted hydrofoil is reasonably simulated by the proposed method. Numerical results clearly reproduce the cavity shedding process, such as cavity development, breaking-off and collapsing in the downstream. Regarding vapor shedding in the cavitating flow around three-dimensional foils, it is primarily attributed to the effect of the re-entrant flow consisting of a re-entrant jet and a pair of side-entrant jets. Formation of the re-entrant jet in the rear part of an attached cavity is affected by collapse of the last shedding vapor. Numerical results also show that the cavity shedding causes the surface pressure fluctuation of the hydrofoil and the force vibration. Accompanying the cavity evolution, the wave of pressure fluctuation propagates in two directions, namely, from the leading edge of the foil to the trailing edge and from the central plane to the side of the hydrofoil along the span. It is seen that the large pressure fluctuation occurs at the central part of the hydrofoil, where the flow incidence is larger.
Numerical Investigations of Passive Scalar Transport in Turbulent Taylor-Couette Flows: Large Eddy Simulation Versus Direct Numerical Simulations
Authors: Salhi Yacine , Si-Ahmed El-Khider , Degrez Gérard , Legrand Jack
Published: April 2012

The highly turbulent flow occurring inside (electro)chemical reactors requires accurate simulation of scalar mixing if computational fluid dynamics (CFD) methods are to be used with confidence in design. This has motivated the present paper, which describes the implementation of a passive scalar transport equation into a hybrid spectral/finite-element code. Direct numerical simulations (DNS) and large eddy simulation (LES) were performed to study the effects of gravitational and centrifugal potentials on the stability of incom-pressible Taylor-Couette flow. The flow is confined between two concentric cylinders with an inner rotating cylinder while the outer one is at rest. The Navier-Stokes equations with the uncoupled convection–diffusion–reaction (CDR) equation are solved using a code named spectral/finite element large eddy simulations (SFELES) which is based on spectral development in one direction combined with a finite element discretization in the remaining directions. The performance of the LES code is validated with published DNS data for channel flow. Velocity and scalar statistics showed good agreement between the current LES predictions and DNS data. Special attention was given to the flow field, in the vicinity of Reynolds number of 68.2 with radii ratio of 0.5. The effect of Sc on the concentration peak is pointed out while the magnitude of heat transfer shows a dependence of the Prandtl number with an exponent of 0.375.
Strongly Interacting Rydberg Excitations of a Cold Atomic Gas
Authors: Dudin Y. O. , Kuzmich A.
Published: April 2012

Ultimate Blockade

A Rydberg atom has an electron in a highly excited energy state, close to being set free, but not quite. Ensembles of such atoms interact strongly, sometimes leading to blockade effects where the excitation of one atom prevents the excitation of another.
Dudin and Kuzmich
(p.
887
, published online 19 April; see the Perspective by

Grangier

) demonstrate the generation of a many-body excitation with no more than one Rydberg atom in a mesoscopic ensemble of ultracold atoms. When the principal quantum number was increased beyond 70, the excitation was converted into a photon. The ability to control the creation of excitations provides a promising system for quantum information storage, as well as a source of correlated photons.
Identification and Mechanism of Evolution of New Alleles Coding for the AIDA-I Autotransporter of Porcine Pathogenic Escherichia coli
Authors: Côté Jean-Philippe , Berthiaume Frédéric , Houle Sébastien , Fairbrother John M. , Dozois Charles M. , Mourez Michael
Published: April 2012

Autotransporters are a large family of virulence factors of Gram-negative bacterial pathogens. The autotransporter adhesin involved in diffuse adherence (AIDA-I) is an outer membrane protein of
Escherichia coli
, which allows binding to epithelial cells as well as the autoaggregation of bacteria. AIDA-I is glycosylated by a specific heptosyltransferase encoded by the
aah
gene that forms an operon with the
aidA
gene.
aidA
is highly prevalent in strains that cause disease in pigs. Nevertheless, there are only two published whole-length sequences for this gene. In this study, we sequenced the
aah
and
aidA
genes of 24
aidA
-positive porcine strains harboring distinct virulence factor profiles. We compared the obtained sequences and performed phylogenetic and pulsed-field electrophoresis analyses. Our results suggest that there are at least 3 different alleles for
aidA
, which are associated with distinct virulence factor profiles. The genes are found on high-molecular-weight plasmids and seem to evolve via shuffling mechanisms, with one of the sequences showing evidence of genetic recombination. Our work suggests that genetic plasticity allows the evolution of
aah-aidA
alleles that are selected during pathogenesis.
Natural Transformation of an Engineered Helicobacter pylori Strain Deficient in Type II Restriction Endonucleases
Authors: Zhang Xue-Song , Blaser Martin J.
Published: April 2012

Restriction-modification (RM) systems are important for bacteria to limit foreign DNA invasion. The naturally competent bacterium
Helicobacter pylori
has highly diverse strain-specific type II systems. To evaluate the roles of strain-specific restriction in
H. pylori
natural transformation, a markerless type II restriction endonuclease-deficient (REd) mutant was constructed. We deleted the genes encoding all four active type II restriction endonucleases in
H. pylori
strain 26695 using
sacB
-mediated counterselection. Transformation by donor DNA with exogenous cassettes methylated by
Escherichia coli
was substantially (1.7 and 2.0 log
10
for
cat
and
aphA
, respectively) increased in the REd strain. There also was significantly increased transformation of the REd strain by donor DNA from other
H. pylori
strains, to an extent corresponding to their shared type II R-M system strain specificity with 26695. Comparison of the REd and wild-type strains indicates that restriction did not affect the length of DNA fragment integration during natural transformation. There also were no differentials in cell growth or susceptibility to DNA damage. In total, the data indicate that the type II REd mutant has enhanced competence with no loss of growth or repair facility compared to the wild type, facilitating
H. pylori
mutant construction and other genetic engineering.
First Isolation of Mycobacterium kyorinense from Clinical Specimens in Brazil
Authors: Campos Carlos Eduardo Dias , Caldas Paulo Cesar de Souza , Ohnishi Hiroaki , Watanabe Takashi , Ohtsuka Kouki , Matsushima Satsuki , Ferreira Nicole Victor , da Silva Mariza Villas Boas , Redner Paulo , de Carvalho Luciana Distásio , Medeiros Reginalda Ferreira de Melo , Abbud Filho Jacyr Antônio , Fandinho Montes Fátima Cristina Onofre , Galvão Teca Calcagno , Ramos Jesus Pais
Published: April 2012

In this article, the first isolation of
Mycobacterium kyorinense
specimens in Brazil is described.
M. kyorinense
is a recently identified species, with a few strains reported only in Japan. The Brazilian isolates were initially identified as
Mycobacterium celatum
by PCR restriction enzyme pattern analysis (PRA) with
hsp65
. However, biochemical tests indicated the same profile of
M. kyorinense
and distinguished them from
M. celatum
and
Mycobacterium branderi
. The sequencing of the
hsp65
,
rpoB
, and 16S rRNA genes allowed the accurate identification of isolates as
M. kyorinense
.
Novel Approach toIn VitroDrug Susceptibility Assessment of Clinical Strains of Leishmania spp
Authors: Fernández Olga , Diaz-Toro Yira , Valderrama Liliana , Ovalle Clemencia , Valderrama Mabel , Castillo Harry , Perez Mauricio , Saravia Nancy Gore
Published: April 2012

Resistance to antimonial drugs has been documented inLeishmaniaisolates transmitted in South America, Europe, and Asia. The frequency and distribution of resistance to these and other antileishmanial drugs are unknown. Technical constraints have limited the assessment of drug susceptibility of clinical strains ofLeishmania. Susceptibility of experimentally selected lines and 130 clinical strains ofLeishmania panamensis,L. braziliensis, andL. guyanensisto meglumine antimoniate and miltefosine was determined on the basis of parasite burden and percentage of infected U-937 human macrophages. Reductions of infection at single predefined concentrations of meglumine antimoniate and miltefosine and 50% effective doses (ED50s) were measured and correlated. The effects of 34°C and 37°C incubation temperatures and different parasite-to-host cell ratios on drug susceptibility were evaluated at 5, 10, and 20 parasites/cell. Reduction of the intracellular burden ofLeishmaniaamastigotes in U-937 cells exposed to the predefined concentrations of meglumine antimoniate or miltefosine discriminated sensitive and experimentally derived resistantLeishmaniapopulations and was significantly correlated with ED50values of clinical strains (for meglumine antimoniate, ρ = −0.926 andP< 0.001; for miltefosine, ρ = −0.906 andP< 0.001). Incubation at 37°C significantly inhibited parasite growth compared to that at 34°C in the absence of antileishmanial drugs and resulted in a significantly lower ED50in the presence of drugs. Susceptibility assessment was not altered by the parasite-to-cell ratio over the range evaluated. In conclusion, measurement of the reduction of parasite burden at a single predetermined drug concentration under standardized conditions provides an efficient and reliable strategy for susceptibility evaluation and monitoring of clinical strains ofLeishmania.
Evaluation of Optimal Storage Temperature, Time, and Transport Medium for Detection of Group B Streptococcus in StrepB Carrot Broth
Authors: Trotman-Grant Ashton , Raney Trisha , Dien Bard Jennifer
Published: April 2012

The performances of the ESwab and Amies transport media were evaluated for optimal survival of group B streptococcus (GBS) in StrepB carrot broth. ESwab was superior to Amies at all temperatures evaluated but was optimal at 21°C and 24°C, whereas recovery in Amies was significantly decreased at these temperatures.
Rapid Identification of Aspergillus terreus from Bronchoalveolar Lavage Fluid by PCR and Electrospray Ionization with Mass Spectrometry
Authors: Modi Dhruvangkumar A. , Farrell John J. , Sampath Rangarajan , Bhatia Nisha S. , Massire Christian , Ranken Ray , Bonomo Robert A.
Published: April 2012

We describe the application of PCR and electrospray-ionization with mass spectrometry (PCR/ESI-MS) to culture-negative bronchoalveolar lavage (BAL) fluid in order to identify septate hyphae noted by Gomori methenamine silver (GMS) staining of the fluid that was obtained from an immunocompromised woman with neutropenia following induction chemotherapy for treatment of acute myelogenous leukemia (AML). The patient was treated with empirical antifungal therapy, including intrathecal amphotericin B, while results of fungal cultures were pending. Ultimately,
Aspergillus terreus
, an amphotericin-resistant mold, was cultured from bilateral brain abscesses. PCR/ESI-MS correctly identified the mold.
Strategy for Rapid Identification and Antibiotic Susceptibility Testing of Gram-Negative Bacteria Directly Recovered from Positive Blood Cultures Using the Bruker MALDI Biotyper and the BD Phoenix System
Authors: Wimmer Jana L. , Long S. Wesley , Cernoch Patricia , Land Geoffrey A. , Davis James R. , Musser James M. , Olsen Randall J.
Published: April 2012

Decreasing the time to species identification and antibiotic susceptibility determination of strains recovered from patients with bacteremia significantly decreases morbidity and mortality. Herein, we validated a method to identify Gram-negative bacteria directly from positive blood culture medium using the Bruker MALDI Biotyper and to rapidly perform susceptibility testing using the BD Phoenix.
Rapid Determination of Methicillin Resistance among Staphylococcus aureus Clinical Isolates by Colorimetric Methods
Authors: Coban Ahmet Yilmaz
Published: April 2012

In the present study, the effectiveness of a rapid and colorimetric nitrate reductase analysis (NRA) method and resazurin microplate assay (REMA) for rapid determination of methicillin resistance among
Staphylococcus aureus
was investigated. A total of 275 clinical isolates of
S. aureus
were included in the present study. Among these isolates, 151 had the
mecA
gene and were resistant to methicillin. The remaining 124 isolates were methicillin susceptible and did not have the
mecA
gene. Cefoxitin MICs of all isolates were detected by NRA, REMA, and reference broth microdilution methods. Category and essential agreement were determined as 100% and 99.6%, respectively, comparing both NRA and REMA with the reference method. No minor, major, or very major discrepancy was observed for either of the methods. The time necessary to have the MIC results was 5 h for NRA, whereas it was 6 h for REMA. Early detection of MRSA is an important public health concern, and the results of this study showed that both of the colorimetric methods are easy to perform and save time in the determination of MRSA. These methods have a potential use for early detection of MRSA for laboratories unable to use molecular techniques.
Validation of Increased Blood Storage Times with the T-SPOT.
TB
Assay with T-Cell
Xtend
Reagent in Individuals with Different Tuberculosis Risk Factors
Authors: Wang Shu-Hua , Stew Samuel S. , Cyktor Joshua , Carruthers Bridget , Turner Joanne , Restrepo Blanca I.
Published: April 2012

We compared the performance of the T-SPOT.
TB
assay with blood used within 0 to 3.5 h after collection (control) to its performance with blood stored for 0 to 3.5, 5 to 8, 18 to 21, or 31 to 33 h with the addition of T-Cell
Xtend
(experimental), using samples from 154 participants. The 95.4% concordance between paired specimens indicated that blood can be stored for up to 33 h prior to T-SPOT.
TB
testing.
Analysis of a Streptococcus pyogenes Puerperal Sepsis Cluster by Use of Whole-Genome Sequencing
Authors: Ben Zakour Nouri L. , Venturini Carola , Beatson Scott A. , Walker Mark J.
Published: April 2012

Between June and November 2010, a concerning rise in the number of cases of puerperal sepsis, a postpartum pelvic bacterial infection contracted by women after childbirth, was observed in the New South Wales, Australia, hospital system. Group A streptococcus (GAS;
Streptococcus pyogenes
) isolates PS001 to PS011 were recovered from nine patients. Pulsed-field gel electrophoresis and
emm
sequence typing revealed that GAS of
emm1.40
,
emm75.0
,
emm77.0
,
emm89.0
, and
emm89.9
were each recovered from a single patient, ruling out a single source of infection. However,
emm28.8
GAS were recovered from four different patients. To investigate the relatedness of these
emm28
isolates, whole-genome sequencing was undertaken and the genome sequences were compared to the genome sequence of the
emm28.4
reference strain, MGAS6180. A total of 186 single nucleotide polymorphisms were identified, for which the phylogenetic reconstruction indicated an outbreak of a polyclonal nature. While two isolates collected from different hospitals were not closely related, isolates from two puerperal sepsis patients from the same hospital were indistinguishable, suggesting patient-to-patient transmission or infection from a common source. The results of this study indicate that traditional typing protocols, such as pulsed-field gel electrophoresis, may not be sensitive enough to allow fine epidemiological discrimination of closely related bacterial isolates. Whole-genome sequencing presents a valid alternative that allows accurate fine-scale epidemiological investigation of bacterial infectious disease.
Performance of the cobas CT/NG Test Compared to the Aptima AC2 and Viper CTQ/GCQ Assays for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae
Authors: Van Der Pol Barbara , Liesenfeld Oliver , Williams James A. , Taylor Stephanie N. , Lillis Rebecca A. , Body Barbara A. , Nye Mindy , Eisenhut Carol , Hook Edward W.
Published: April 2012

The next-generation amplification test for
Chlamydia trachomatis
and
Neisseria gonorrhoeae
(Roche cobas 4800), a fully automated system, was compared head to head, using female samples, to Gen-Probe Aptima Combo 2 and BD ProbeTec using Viper. Endocervical swabs, female urine, and endocervical samples in liquid-based cytology medium were run on at least two of three platforms. A total of 4,316 samples were evaluated, and 281 chlamydial and 69 gonococcal infections were identified. Estimates of sensitivity and specificity were obtained relative to the patient infection standard (PIS) and using latent class analysis (LCA). Chlamydia sensitivity estimates ranged from 86.9 to 95.6% using PIS and 97.6 to 98% using LCA. Specificity was ≥99.6% for all sample types. Sensitivity ranged from 95.6 to 100% using PIS and 96.9 to 100% using LCA for the detection of gonococcal infections. Specificity for gonococcal infections was ≥99.8%. cobas 4800 performance was equivalent to the comparator assays (all
P
values, >0.05), and the fully automated system provides high laboratory efficiency.
Recombinase Polymerase Amplification Assay for Rapid Detection of Francisella tularensis
Authors: Euler Milena , Wang Yongjie , Otto Peter , Tomaso Herbert , Escudero Raquel , Anda Pedro , Hufert Frank T. , Weidmann Manfred
Published: April 2012

Several real-time PCR approaches to develop field detection for
Francisella tularensis
, the infectious agent causing tularemia, have been explored. We report the development of a novel qualitative real-time isothermal recombinase polymerase amplification (RPA) assay for use on a small ESEQuant Tube Scanner device. The analytical sensitivity and specificity were tested using a plasmid standard and DNA extracts from infected rabbit tissues. The assay showed a performance comparable to real-time PCR but reduced the assay time to 10 min. The rapid RPA method has great application potential for field use or point-of-care diagnostics.
Simultaneous Detection of Seven Enteric Viruses Associated with Acute Gastroenteritis by a Multiplexed Luminex-Based Assay
Authors: Liu Yan , Xu Zi-qian , Zhang Qing , Jin Miao , Yu Jie-mei , Li Jin-song , Liu Na , Cui Shu-xian , Kong Xiang-yu , Wang Hong , Li Hui-ying , Cheng Wei-xia , Ma Xue-jun , Duan Zhao-jun
Published: April 2012

Rapid and broad diagnostic methods are needed for the identification of viral agents of gastroenteritis. In this study, we used Luminex xMAP technology to develop a multiplexed assay for the simultaneous identification of major enteric viral pathogens, including rotavirus A (RVA), noroviruses (NoVs) (including genogroups GI and GII), sapoviruses (SaV), human astrovirus (HAstV), enteric adenoviruses (EAds), and human bocavirus 2 (HBoV2). The analytical sensitivity allowed detection of 103(EAds, HBoV2, and RVA) and 104(NoV GI and GII, SaV, and HAstV) copies per reaction mixture. Compared to conventional PCR, the Luminex-based assay yielded greater than 75% sensitivity and 97% specificity for each virus, and the kappa correlation for detection of all viruses ranged from 0.75 to 1.00. In conclusion, this multiplexed Luminex-based assay provides a potentially rapid, high-throughput, and maneuverable diagnostic tool for major viral pathogens associated with gastroenteritis.