bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular phylogeny of Nitidulidae: assessment of subfamilial and tribal classification and formalization of the family Cybocephalidae (Coleoptera: Cucujoidea)
Authors: CLINE ANDREW R. , SMITH TREVOR R. , MILLER KELLY , MOULTON MATTHEW , WHITING MICHAEL , AUDISIO PAOLO
Published: June 2014

We present a molecular phylogeny of Nitidulidae based on thirty ingroup taxa representing eight of the ten currently recognized subfamilies. Approximately 10 K base pairs from seven loci (12S, 16S, 18S, 28S, COI, COII and H3) were used for the phylogenetic reconstruction. The phylogeny supports the following main conclusions: (i) Cybocephalidae are formally recognized as a distinct family not closely related to Nitidulidae and its constituent taxa are defined; (ii) Kateretidae are sister to Nitidulidae; (iii) Cryptarchinae are monophyletic and sister to the remaining nitidulid subfamilies; (iv) subfamily Prometopinae stat. res. is reinstated and defined, to accommodate taxa allied to Axyra Erichson, Prometopia Erichson and Megauchenia MacLeay; (v) Amphicrossinae, Carpophilinae and Epuraeinae are shown to be closely related taxa within a well‐supported monophyletic clade; (vi) tribal affinities and respective monophyly within Nitidulinae are poorly resolved by our data and must be more rigorously tested as there was little or no support for prior morphologically based tribes or genus‐level complexes; (vii) Nitidulinae are found to be paraphyletic with respect to Cillaeinae and Meligethinae, suggesting that they should either be subsumed as tribes, or Nitidulinae should be divided into several subfamilies to preserve the status of Cillaeinae and Meligethinae; (viii) Teichostethus Sharp stat. res. is not a synonym of Hebascus Erichson and the former is reinstated as a valid genus. These conclusions and emendations are discussed in detail and presented within a morphological framework.
Where did platelets go in 2012? A survey of platelet transfusion practice in the North of England
Authors: Charlton A. , Wallis J. , Robertson J. , Watson D. , Iqbal A. , Tinegate H.
Published: June 2014

Objectives

To record the fate of transfused platelet doses in the North of England, and thereby assist with demand‐planning and help target teaching on appropriate use.

Background

Platelet use has risen recently to the extent that donation practice has changed to meet demand. Two national comparative audits have shown inappropriate use and the 2010 audit concluded that current UK guidelines for platelet usage should be completely implemented at a local level. It is necessary to know how platelets are used and by whom in order to facilitate guideline concordance.

Methods

All hospital trusts in the North East and Cumbria recorded data on all platelet doses transfused in two separate 4‐week periods in 2012. Data were entered onto an electronic survey tool.

Results

One thousand and five hundred and seventy‐four reports were received, documenting 1937 transfused doses – 96% of total issues for the study periods. One thousand and forty‐five platelet doses (54%) were given for haematological indications. The second commonest indication was cardiac surgery (201 doses, 10% of the total) followed by non‐haematological oncology (127 doses, 6.5%), critical care (106 doses, 5%) and liver disease (50 doses, 2·5%).

The commonest haematological indication was acute myeloid leukaemia, 310 doses, (16% of all platelet use), followed by stem cell transplantation, 271 doses (14%).

Seventy‐two percent of platelet doses were given prophylactically, the majority without any planned procedure.

Conclusion

The commonest indication for platelet use, where reinforcement of guidelines will be productive, is prophylaxis in haematological disease. Use of platelets in cardiac surgery is also worthy of close scrutiny.
Simulation and Measurement of Through–Wall Residual Stresses in a Structural Weld Overlaid Pressurizer Nozzle
Authors: Marlette Stephen , Freyer Paula , Smith Michael , Goodfellow Andrew , Pitoiset Xavier , Voigt Bradley , Rishel Rick , Kingston Ed
Published: June 2014

Full structural weld overlays (FSWOLs) have been used extensively as a repair/mitigation technique for primary water stress corrosion cracking in pressurizer nozzle dissimilar metal (DM) welds. To support an approved FSWOL design and safety submission for British Energy pressurized water reactor (PWR) nozzles, an in-depth evaluation was performed to assess the effects of a FSWOL on the through wall residual stress distribution in safety/relief pressurizer nozzles. Two safety/relief pressurizer nozzle mockups were fabricated based on British Energy’s PWR nozzle design. One mockup included the nozzle to safe-end DM weld and the safe-end to stainless steel weld, while the second mockup included the DM weld, the stainless steel weld, and a Westinghouse designed structural weld overlay. The mockups were fabricated utilizing materials and techniques that represented the plant specific nozzles as closely as possible and detailed welding parameters were recorded during fabrication. All welds were subsequently nondestructively evaluated (NDE). A thorough review of the detailed fabrication records and the NDE results was performed and several circumferential positions were selected on each mockup for subsequent residual stress measurement. The through wall residual stress profiles were experimentally measured through the DM weld centerline at the selected circumferential positions using both the deep-hole drilling (DHD) and incremental deep-hole drilling (iDHD) measurement techniques. In addition to experimental residual stress measurements, the through-wall residual stress profiles were simulated using a 2D axisymmetric ansys™ finite element (FE) model. The model utilized the application of temperature constraints on the weld elements to simulate the thermal welding cycle which greatly simplified the simulation as compared with detailed heat source modeling methods. Kinematic strain hardening was used for material modeling of the weld and base metals. A range of residual weld stress profiles was calculated by varying the time at which the temperature constraints were applied to the model. The simulation results were compared with the measurement results. It was found that the effects of the FSWOL were principally threefold. Specifically, the FSWOL causes a much deeper compressive stress field, i.e., the overlay shifts tension out toward the outside diameter (OD) surface. Furthermore, the FSWOL reduces tension in the underlying dissimilar metal weld, and finally, the FSWOL causes higher peak compressive and tensile residual stresses, both of which move deeper into the nozzle wall after the overlay is applied. Relatively good agreement was observed between the FE results and the measurements results.
Status of Alloy 800 H in Considerations for the Gen IV Nuclear Energy Systems
Authors: Ren Weiju , Swindeman Robert
Published: June 2014

Alloy 800 H is currently under consideration for applications in the next generation nuclear plant (NGNP) at operational temperatures above 750 °C. This paper first describes service requirements of the nuclear system for structural materials; and then an extensive review of Alloy 800 H is given on its codification with respect to development and research history, mechanical behavior and design allowables, metallurgical aging resistance, environmental effect considerations, data requirements and availability, weldments, as well as many other aspects relevant to the intended nuclear application. Finally, further research and development activities to support the materials qualification are suggested.
Equation Solving DRESOR Method for Radiative Transfer in Three-Dimensional Isotropically Scattering Media
Authors: Huang Zhifeng , Zhou Huaichun , Wang Guihua , Hsu Pei-feng
Published: June 2014

Distributions of ratios of energy scattered or reflected (DRESOR) method is a very efficient tool used to calculate radiative intensity with high directional resolution, which is very useful for inverse analysis. The method is based on the Monte Carlo (MC) method and it can solve radiative problems of great complexity. Unfortunately, it suffers from the drawbacks of the Monte Carlo method, which are large computation time and unavoidable statistical errors. In this work, an equation solving method is applied to calculate DRESOR values instead of using the Monte Carlo sampling in the DRESOR method. The equation solving method obtains very accurate results in much shorter computation time than when using the Monte Carlo method. Radiative intensity with high directional resolution calculated by these two kinds of DRESOR method is compared with that of the reverse Monte Carlo (RMC) method. The equation solving DRESOR (ES-DRESOR) method has better accuracy and much better time efficiency than the Monte Carlo based DRESOR (original DRESOR) method. The ES-DRESOR method shows a distinct advantage for calculating radiative intensity with high directional resolution compared with the reverse Monte Carlo method and the discrete ordinates method (DOM). Heat flux comparisons are also given and the ES-DRESOR method shows very good accuracy.
Effect of Electric Field Distribution Generated in a Microspace on Pool Boiling Heat Transfer
Authors: Kano Ichiro
Published: June 2014

This study describes the effect of an electric field on nucleate boiling and critical heat flux (CHF) in pool boiling. A dielectric liquid of AE-3000 was used as the working fluid. A heating surface was polished to a surface roughness of 0.05 μm. A microsized electrode, in which slits were provided, was designed to generate a nonuniform electric field and produce electrohydrodynamic (EHD) effects with the application of high dc voltages. The obtained results confirmed CHF enhancement as the EHD effects increased CHF to 86.2 W/cm2 with a voltage of −3000 V, which was four times greater than pool boiling in the absence of the electrode. The usual traveling wave on the bubble interface, induced by the Kelvin–Helmholtz instability, was modified by adding the EHD effects. The traveling wave model exhibits the essential features of the phenomenon and shows good agreement with the experimental data.
The Gas Bearing Interface of Opposed Recording Heads in a Disk Drive Utilizing Helium and Thin Titanium Foil Disks
Authors: White James
Published: June 2014

Increased storage capacity and decreased power consumption are two key motivations in the development of hard disk drive (HDD) storage products. Two ideas that address these areas have recently received attention in the literature. These are (1) the use of helium instead of air as the working gas in the drive and (2) the incorporation of a thin metal foil as the disk substrate, replacing the much thicker aluminum or glass substrate of the hard disk (HD). The work that has been previously reported considered either the use of helium or thin foil substrates, but not both. This paper does consider both. It reports dynamic gas bearing simulation results for the helium filled interface between opposed recording heads and a disk whose substrate is a thin titanium foil. Motivation for the selection of titanium as the foil material is described in the paper. The thickness of the foil is chosen so as to achieve an optimal combination of centrifugal force and bending force that will provide required disk flatness and stability during high-speed rotation. Large-scale dynamic simulation is used to track the response of the recording head slider-foil disk interface due to mechanical shock in the vertical, pitch, and roll directions. Results are described and compared with those of the configuration that includes helium and a HD. Attention is focused on response to off-design conditions that can create head crash with the HD.
Aerodynamic Design of S-Shaped Diffusers Using Ball–Spine Inverse Design Method
Authors: Madadi A. , Kermani M. J. , Nili-Ahmadabadi M.
Published: June 2014

Recently, an inverse design algorithm called ball–spine algorithm (BSA) was introduced for the design of 2D ducts. In this approach, the walls are considered as a set of virtual balls that can move freely along the straight directions called spines. In the present work, the method is developed for quasi-three-dimensional (quasi-3D) design of S-shaped ducts with a predefined width. To do so, the upper and lower lines of the S-duct symmetric section are modified under the BSA and then, the 3D S-duct geometry is obtained based on elliptic cross-sectional profiles. The target pressure distributions (TPDs) along the upper and lower lines are prescribed so that separation does not occur. Finally, the flow through the designed S-duct is numerically analyzed using a viscous flow solver with the SST turbulence model to validate the designed S-duct performance. The performance of the designed S-duct is compared to original and optimized versions of a benchmark S-duct diffuser. Results show that the present S-duct has a better performance.
Dynamic Performance Characteristics of Floating-Ring Bearings With Varied Oil-Injection Swirl-Control Angles
Authors: Tamunodukobipi Daniel , Ho Kim Chang , Lee Yong-Bok
Published: June 2014

Hydrodynamic instability is a prime causative of performance irregularities and violent vibrations in floating-ring bearing (FRB) supported turbosystems. The quest for energy-efficient solutions to this has stimulated the development of diverse FRB design-geometries, dimensional relationships, and surface-contours. Unfortunately, these modifications are characterized mainly by model-predictors, which results lack sufficient test-data to benchmark their authenticities. This work presents the concept and the test-data of flow redirection in FRBs by using an oil-injection swirl-control mechanism (OISCM) to attenuate rotordynamic instabilities. FRBs with radius ratio = 1.75 and clearance ratio = 1.5 are tested for various OISCM angles (0 deg, 30 deg, and 60 deg) and under a specific load = 50 kN/m2. The test results indicate that FRBs with OISCM demonstrate substantial improvements in damping and stability characteristics. Their whirl-frequency-ratio (WFR) and cross-coupled forces are lower because of improved symmetry of films' pressure-forces (Kxx ≈ Kyy). Although the magnitudes of direct damping are higher (|Cxx| = 16.92 kN s/m for 60 deg and 6.03 kN s/m for 0 deg), the load capacity (Kxx) is slightly lower than the normal (0 deg), injection. Nonetheless, this discrepancy in load capacities becomes insignificant for speeds above 22 krpm. The WFR and subsynchronous amplitudes, which are graphic reflections of the bearing-based instability, become progressively smaller with increasing OISCM angle. However, this advantage at elevated speeds can only be sustained by a corresponding increase in oil-supply pressure to circumvent the advent of a starved inner-film and its attendant imbalance response and thermal growth. In closure, the OISCM bearing is more effective for mitigating rotordynamic instabilities in turborotors than conventional FRBs.
Calculating and visualizing the density of states for simple quantum mechanical systems
Authors: Mulhall Declan , Moelter Matthew J.
Published: June 2014

We present a graphical approach to understanding the degeneracy, density of states, and cumulative state number for some simple quantum systems. By taking advantage of basic computing operations, we define a straightforward procedure for determining the relationship between discrete quantum energy levels and the corresponding density of states and cumulative level number. The density of states for a particle in a rigid box of various shapes and dimensions is examined and graphed. It is seen that the dimension of the box, rather than its shape, is the most important feature. In addition, we look at the density of states for a multi-particle system of identical bosons built on the single-particle spectra of those boxes. A simple model is used to explain how the N-particle density of states arises from the single particle system it is based on.
A granular fountain
Authors: Urbina R. E. , Díaz K. K. , Bramer-Escamilla W. , Sánchez I.
Published: June 2014

We present a fascinating experiment, with great potential for entry-level educational and public outreach applications: a granular fountain. It is an example of the rich and sometimes counterintuitive phenomena that takes place when fine sand is vertically vibrated at low frequencies. We offer guidelines for reproducing the experiment and also a short discussion on the physics behind the effect.
Electron spin and probability current density in quantum mechanics
Authors: Hodge W. B. , Migirditch S. V. , Kerr W. C.
Published: June 2014

This paper analyzes how the existence of electron spin changes the equation for the probability current density in the quantum-mechanical continuity equation. A spinful electron moving in a potential energy field experiences the spin-orbit interaction, and that additional term in the time-dependent Schrödinger equation places an additional spin-dependent term in the probability current density. Further, making an analogy with classical magnetostatics hints that there may be an additional magnetization current contribution. This contribution seems not to be derivable from a non-relativistic time-dependent Schrödinger equation, but there is a procedure described in the quantum mechanics textbook by Landau and Lifschitz to obtain it. We utilize and extend their procedure to obtain this magnetization term, which also gives a second derivation of the spin-orbit term. We conclude with an evaluation of these terms for the ground state of the hydrogen atom with spin-orbit interaction. The magnetization contribution is generally the larger one, except very near an atomic nucleus.
An introduction to the inverse quantum bound-state problem in one dimension
Authors: Gutierrez Thomas D.
Published: June 2014

A technique to reconstruct one-dimensional, reflectionless potentials and the associated quantum wave functions starting from a finite number of known energy spectra is discussed. The method is demonstrated using spectra that scale like the lowest energy states of standard problems encountered in the undergraduate curriculum, such as the infinite square well and the simple harmonic oscillator.
Inexpensive electronics and software for photon statistics and correlation spectroscopy
Authors: Gamari Benjamin D. , Zhang Dianwen , Buckman Richard E. , Milas Peker , Denker John S. , Chen Hui , Li Hongmin , Goldner Lori S.
Published: June 2014

Single-molecule-sensitive microscopy and spectroscopy are transforming biophysics and materials science laboratories. Techniques such as fluorescence correlation spectroscopy (FCS) and single-molecule sensitive fluorescence resonance energy transfer (FRET) are now commonly available in research laboratories but are as yet infrequently available in teaching laboratories. We describe inexpensive electronics and open-source software that bridges this gap, making state-of-the-art research capabilities accessible to undergraduates interested in biophysics. We include a discussion of the intensity correlation function relevant to FCS and how it can be determined from photon arrival times. We demonstrate the system with a measurement of the hydrodynamic radius of a protein using FCS that is suitable for the undergraduate teaching laboratory. The FPGA-based electronics, which are easy to construct, are suitable for more advanced measurements as well, and several applications are described. As implemented, the system has 8 ns timing resolution, can control up to four laser sources, and can collect information from as many as four photon-counting detectors.
Simulation of the active Brownian motion of a microswimmer
Authors: Volpe Giorgio , Gigan Sylvain , Volpe Giovanni
Published: June 2014

Unlike passive Brownian particles, active Brownian particles, also known as microswimmers, propel themselves with directed motion and thus drive themselves out of equilibrium. Understanding their motion can provide insight into out-of-equilibrium phenomena associated with biological examples such as bacteria, as well as with artificial microswimmers. We discuss how to mathematically model their motion using a set of stochastic differential equations and how to numerically simulate it using the corresponding set of finite difference equations both in homogenous and complex environments. In particular, we show how active Brownian particles do not follow the Maxwell-Boltzmann distribution—a clear signature of their out-of-equilibrium nature—and how, unlike passive Brownian particles, microswimmers can be funneled, trapped, and sorted.
Birds on power lines
Authors: Arnaldo Redinz José
Published: June 2014

Why can a bird safely rest on a high-voltage power line? We discuss three effects that can lead to the development of voltages and currents in the bird's body. To explain the absence of electric shocks, we give numerical estimates of these voltages and currents obtained from the standard solution for the voltage along a two-wire transmission line.
Distinguishing between “change” and “amount” infinitesimals in first-semester calculus-based physics
Authors: Von Korff Joshua , Sanjay Rebello N.
Published: June 2014

From the perspective of an introductory calculus course, an integral is simply a Riemann sum: a particular limit of a sum of small quantities. However, students connect those mathematical quantities to physical representations in different ways. For example, integrals that add up mass and integrals that add up displacement use infinitesimals differently. Students who are not cognizant of these differences may not understand what they are doing when they integrate. Further, they may not understand how to set up an integral. We propose a framework for scaffolding students' knowledge of integrals using a distinction between “change” and “amount” infinitesimals. In support of the framework, we present results from two qualitative studies about student understanding of integration.
The genomic landscape underlying phenotypic integrity in the face of gene flow in crows
Authors: Poelstra J. W. , Vijay N. , Bossu C. M. , Lantz H. , Ryll B. , Müller I. , Baglione V. , Unneberg P. , Wikelski M. , Grabherr M. G. , Wolf J. B. W.
Published: June 2014

Crows of a feather flock together

Closely related species with overlapping ranges typically evolve genetic barriers to prevent crossbreeding. Poelstraet al.sequenced genes from two species of central European crows: gray-bodied hooded crows and black carrion crows (see the Perspective by de Knijff). Although most of the genomes shared genes between the two species, one region that affected coat color and color vision differed. The authors suggest that black and gray-coated crows prefer to mate with birds like themselves.

Science, this issue p.1410; see also p.1345
Triple-Color FRET Analysis Reveals Conformational Changes in the WIP-WASp Actin-Regulating Complex
Authors: Fried Sophia , Reicher Barak , Pauker Maor H. , Eliyahu Shani , Matalon Omri , Noy Elad , Chill Jordan , Barda-Saad Mira
Published: June 2014

Two interaction sites provide a mechanism to finely balance the activity and degradation of an actin-regulating protein complex.
Serratia marcescens
arn
, a PhoP-Regulated Locus Necessary for Polymyxin B Resistance
Authors: Lin Quei Yen , Tsai Yi-Lin , Liu Ming-Che , Lin Wei-Cheng , Hsueh Po-Ren , Liaw Shwu-Jen
Published: June 2014

Polymyxins, which are increasingly being used to treat infections caused by multidrug-resistant bacteria, perform poorly against
Serratia marcescens
. To investigate the underlying mechanisms, Tn
5
mutagenesis was performed and two mutants exhibiting increased polymyxin B (PB) susceptibility were isolated. The mutants were found to have Tn
5
inserted into the
arnB
and
arnC
genes. In other bacteria,
arnB
and
arnC
belong to the seven-gene
arn
operon, which is involved in lipopolysaccharide (LPS) modification. LPSs of
arn
mutants had greater PB-binding abilities than that of wild-type LPS. Further, we identified PhoP, a bacterial two-component response regulator, as a regulator of PB susceptibility in
S. marcescens
. By the reporter assay, we found PB- and low-Mg
2+
-induced expression of
phoP
and
arn
in the wild-type strain but not in the
phoP
mutant. Complementation of the
phoP
mutant with the full-length
phoP
gene restored the PB MIC and induction by PB and low Mg
2+
levels, as in the wild type. An electrophoretic mobility shift assay (EMSA) further demonstrated that PhoP bound directly to the
arn
promoter. The PB challenge test confirmed that pretreatment with PB and low Mg
2+
levels protected
S. marcescens
from a PB challenge in the wild-type strain but not in the
phoP
mutant. Real-time reverse transcriptase-PCR also indicated that PB serves as a signal to regulate expression of
ugd
, a gene required for LPS modification, in
S. marcescens
through a PhoP-dependent pathway. Finally, we found that PB-resistant clinical isolates displayed greater expression of
arnA
upon exposure to PB than did susceptible isolates. This is the first report to describe the role of
S. marcescens
arn
in PB resistance and its modulation by PB and Mg
2+
through the PhoP protein.
Mathematical Model To Quantify the Effects of Risk Factors on Carbapenem-Resistant Acinetobacter baumannii
Authors: Tan Michelle W. , Lye David C. , Ng Tat-Ming , Nikolaou Michael , Tam Vincent H.
Published: June 2014

Carbapenem-resistant
Acinetobacter baumannii
(CRAB) infections are increasing, and they are associated with an increased risk of mortality in hospitalized patients. Linear regression is commonly used to identify concurrent trends, but it cannot quantify the relationship between risk factors and resistance. We developed a model to quantify the impact of antibiotic consumption on the prevalence of CRAB over time. Data were collected from January 2007 to June 2013 from our institution. Quarterly antibiotic consumption was expressed as defined daily dose/1,000 inpatient days. Six-month prevalence of CRAB was expressed as a percentage of all nonrepeat
A. baumannii
isolates tested. Individual trends were identified using linear regression. Antibiotic consumption from 2007 to 2011 was input as a step function in a relationship with CRAB. Model fit was evaluated by visual inspection and the residual sum of squares. The final model was validated using the best-fit (95% confidence interval) parameter estimates and antibiotic consumption to predict CRAB prevalence from January 2012 to June 2013. Cefepime, ertapenem, and piperacillin-tazobactam consumption and CRAB prevalence increased significantly over time. CRAB prevalence was best correlated to ertapenem (use sensitive;
r
2
= 0.76), and accounting for additional concurrent antibiotic use did not significantly improve model fit. Prospective validation with ertapenem consumption correlated well with CRAB observations, suggesting good predicting ability of the model. Our model provided the quantitative impact of antibiotic consumption on CRAB. We plan to further refine this model to account for multiple risk factors. Interventions should focus on controlling risk factors with the highest impact on resistance.
Renal Handling of Amphotericin B and Amphotericin B-Deoxycholate and Potential Renal Drug-Drug Interactions with Selected Antivirals
Authors: Trejtnar František , Mandíková Jana , Kočíncová Jana , Volková Marie
Published: June 2014

Amphotericin B (AmB) is excreted via the renal excretion route. This excretion process may result in nephrotoxicity. However, relevant information on the precise renal excretion mechanisms is not available. The aim of the study was to analyze the possible interaction of AmB or its prodrug AmB deoxycholate (AmB-DOC) with the typical renal organic anion transporters (OATs) and organic cation transporters (OCTs), using cellular and organ models. The relevant transport systems were then investigated in terms of the drug-drug interactions of AmB-DOC with antivirals that might potentially be used concomitantly. To analyze the renal excretion mechanisms of [
3
H]AmB, perfused rat kidney was employed. HeLa and MDCK II cells transiently transfected with human OAT1 (hOAT1) or hOCT2 were used as the cellular models. A significant tubular secretion of AmB was demonstrated in the perfused rat kidney. The cellular studies performed confirmed the active transport of AmB into cells. AmB did not interact with hOAT1 but strongly inhibited hOCT2. In contrast, AmB-DOC inhibited both hOAT1 and hOCT2. However, [
3
H]AmB cellular uptake by hOAT1 and hOCT2 was not found. AmB-DOC interacted significantly with adefovir, tenofovir, and cidofovir in hOAT1-transfected cells at supratherapeutic concentrations. In conclusion, the significant potency of AmB and AmB-DOC for inhibiting the transporters was demonstrated in this study. The secretion of AmB in the renal tubules is likely not related to the transporters here, since the drug was not proven to be a substrate for them. Drug-drug interactions of AmB and the antivirals used in this study on the investigated transporters are not probable.
Prevention of Transmission of Multidrug-Resistant Organisms during Catheter Exchange using Antimicrobial Catheters
Authors: Jamal Mohamed A. , Rosenblatt Joel , Jiang Ying , Hachem Ray , Chaftari Ann-Marie , Raad Issam I.
Published: June 2014

Exchanging a central venous catheter (CVC) over a guide wire for a fresh uncoated CVC in the presence of bacteremia can result in cross-infection of the newly exchanged CVC. A recent retrospective clinical study showed that exchanging a catheter over a guide wire in the presence of bacteremia using an antimicrobial minocycline-rifampin (M/R) catheter may improve outcomes. To expand on this, we developed an
in vitro
cross-contamination model of exchange to evaluate the efficacy of different antimicrobial CVCs in preventing cross-contamination of multidrug-resistant organisms during exchange. Uncoated CVCs were allowed to form biofilm by methicillin-resistant
Staphylococcus aureus
(MRSA),
Staphylococcus epidermidis
,
Escherichia coli
,
Pseudomonas aeruginosa
, and
Candida albicans
. After 24 h, the biofilm-colonized CVCs were placed in a glass tube containing bovine calf serum plus Mueller-Hinton broth, and each catheter was exchanged over a guide wire for a fresh uncoated or an M/R-, chlorhexidine-silver sulfadiazine (CHX/SS)-, or chlorhexidine-M/R (CHX-M/R)-coated CVC. Cross-contamination of exchanged catheters was enumerated by sonication and quantitative plating methods. The exchange of M/R CVCs completely prevented cross-contamination by MRSA biofilms compared to control exchanged CVCs (
P
< 0.0001). Exchange with CHX/SS CVCs reduced but did not completely prevent cross-contamination by MRSA (
P
= 0.005). Exchange with CHX-M/R CVCs completely prevented cross-contamination by MRSA,
P. aeruginosa
, and
C. albicans
biofilms (
P
< 0.0001). Furthermore, CHX-M/R CVCs were superior to M/R CVCs against
P. aeruginosa
and
C. albicans
(
P
= 0.003) and were superior to CHX/SS CVCs against MRSA and
P. aeruginosa
(
P
= 0.01). In conclusion, exchange with the novel CHX-M/R CVC was the only exchange effective in completely and concurrently preventing cross-contamination from bacteria and
Candida
.
Draft Genome Sequence of a Legionella pneumophila Serogroup 4 Strain Causing Legionellosis
Authors: Okamoto Akira , Lee Hiromichi , Yabutani Mitsutaka , Yamada Keiko , Ohta Michio
Published: June 2014

Here, we report the draft genome sequence of the
Legionella pneumophila
Nagoya-1 strain, serogroup 4, which was isolated from a clinical sample from a patient with legionellosis. Several virulence-associated genes, including those encoding the type IV (Dot/Icm) secretion system and effector proteins, were highly conserved.
Actin Pedestal Formation by Enterohemorrhagic Escherichia coli Enhances Bacterial Host Cell Attachment and Concomitant Type III Translocation
Authors: Battle Scott E. , Brady Michael J. , Vanaja Sivapriya Kailasan , Leong John M. , Hecht Gail A.
Published: June 2014

Attachment of enterohemorrhagic
Escherichia coli
(EHEC) to intestinal epithelial cells is critical for colonization and is associated with localized actin assembly beneath bound bacteria. The formation of these actin “pedestals” is dependent on the translocation of effectors into mammalian cells via a type III secretion system (T3SS). Tir, an effector required for pedestal formation, localizes in the host cell plasma membrane and promotes attachment of bacteria to mammalian cells by binding to the EHEC outer surface protein Intimin. Actin pedestal formation has been shown to foster intestinal colonization by EHEC in some animal models, but the mechanisms responsible for this remain undefined. Investigation of the role of Tir-mediated actin assembly promoting host cell binding is complicated by other, potentially redundant EHEC-encoded binding pathways, so we utilized cell binding assays that specifically detect binding mediated by Tir-Intimin interaction. We also assessed the role of Tir-mediated actin assembly in two-step assays that temporally segregated initial translocation of Tir from subsequent Tir-Intimin interaction, thereby permitting the distinction of effects on translocation from effects on cell attachment. In these experimental systems, we compromised Tir-mediated actin assembly by chemically inhibiting actin assembly or by infecting mammalian cells with EHEC mutants that translocate Tir but are specifically defective in Tir-mediated pedestal formation. We found that an inability of Tir to promote actin assembly resulted in a significant and striking decrease in bacterial binding mediated by Tir and Intimin. Bacterial mutants defective for pedestal formation translocated type III effectors to mammalian cells with reduced efficiency, but the decrease in translocation could be entirely accounted for by the decrease in host cell attachment.
Characterization of Two UDP-Gal:GalNAc-Diphosphate-Lipid β1,3-Galactosyltransferases WbwC from Escherichia coli Serotypes O104 and O5
Authors: Wang Shuo , Czuchry Diana , Liu Bin , Vinnikova Anna N. , Gao Yin , Vlahakis Jason Z. , Szarek Walter A. , Wang Lei , Feng Lu , Brockhausen Inka
Published: June 2014

Escherichia coli
displays O antigens on the outer membrane that play an important role in bacterial interactions with the environment. The O antigens of enterohemorrhagic
E. coli
O104 and O5 contain a Galβ1-3GalNAc disaccharide at the reducing end of the repeating unit. Several other O antigens contain this disaccharide, which is identical to the mammalian O-glycan core 1 or the cancer-associated Thomsen-Friedenreich (TF) antigen. We identified the
wbwC
genes responsible for the synthesis of the disaccharide in
E. coli
serotypes O104 and O5. To functionally characterize WbwC, an acceptor substrate analog, GalNAcα-diphosphate-phenylundecyl, was synthesized. WbwC reaction products were isolated by high-pressure liquid chromatography and analyzed by mass spectrometry, nuclear magnetic resonance, galactosidase and O-glycanase digestion, and anti-TF antibody. The results clearly showed that the Galβ1-3GalNAcα linkage was synthesized, confirming WbwC
ECO104
and WbwC
ECO5
as UDP-Gal:GalNAcα-diphosphate-lipid β1,3-Gal-transferases. Sequence analysis revealed a conserved DxDD motif, and mutagenesis showed the importance of these Asp residues in catalysis. The purified enzymes require divalent cations (Mn
2+
) for activity and are specific for UDP-Gal and GalNAc-diphosphate lipid substrates. WbwC was inhibited by bis-imidazolium salts having aliphatic chains of 18 to 22 carbons. This work will help to elucidate mechanisms of polysaccharide synthesis in pathogenic bacteria and provide technology for vaccine synthesis.
Alkali Metals in Addition to Acidic pH Activate the EvgS Histidine Kinase Sensor in Escherichia coli
Authors: Eguchi Yoko , Utsumi Ryutaro
Published: June 2014

Two-component signal transduction systems (TCSs) in bacteria perceive environmental stress and transmit the information via phosphorelay to adjust multiple cellular functions for adaptation. The EvgS/EvgA system is a TCS that confers acid resistance to
Escherichia coli
cells. Activation of the EvgS sensor initiates a cascade of transcription factors, EvgA, YdeO, and GadE, which induce the expression of a large group of acid resistance genes. We searched for signals activating EvgS and found that a high concentration of alkali metals (Na
+
, K
+
) in addition to low pH was essential for the activation. EvgS is a histidine kinase, with a large periplasmic sensor region consisting of two tandem PBPb (bacterial periplasmic solute-binding protein) domains at its N terminus. The periplasmic sensor region of EvgS was necessary for EvgS activation, and Leu152, located within the first PBPb domain, was involved in the activation. Furthermore, chimeras of EvgS and PhoQ histidine kinases suggested that alkali metals were perceived at the periplasmic sensor region, whereas the cytoplasmic linker domain, connecting the transmembrane region and the histidine kinase domain, was required for low-pH perception.
Sensitive and Selective Culture Medium for Detection of Environmental Clostridium difficile Isolates without Requirement for Anaerobic Culture Conditions
Authors: Cadnum Jennifer L. , Hurless Kelly N. , Deshpande Abhishek , Nerandzic Michelle M. , Kundrapu Sirisha , Donskey Curtis J.
Published: June 2014

Effective and easy-to-use methods for detecting
Clostridium difficile
spore contamination would be useful for identifying environmental reservoirs and monitoring the effectiveness of room disinfection. Culture-based detection methods are sensitive for detecting
C. difficile
, but their utility is limited due to the requirement of anaerobic culture conditions and microbiological expertise. We developed a low-cost selective broth medium containing thioglycolic acid and
l
-cystine, termed
C. difficile
brucella broth with thioglycolic acid and
l
-cystine (CDBB-TC), for the detection of
C. difficile
from environmental specimens under aerobic culture conditions. The sensitivity and specificity of CDBB-TC (under aerobic culture conditions) were compared to those of CDBB (under anaerobic culture conditions) for the recovery of
C. difficile
from swabs collected from hospital room surfaces. CDBB-TC was significantly more sensitive than CDBB for recovering environmental
C. difficile
(36/41 [88%] versus 21/41 [51%], respectively;
P
= 0.006).
C. difficile
latex agglutination, an enzyme immunoassay for toxins A and B or glutamate dehydrogenase, and a PCR for toxin B genes were all effective as confirmatory tests. For 477 total environmental cultures, the specificity of CDBB-TC versus that of CDBB based upon false-positive yellow-color development of the medium without recovery of
C. difficile
was 100% (0 false-positive results) versus 96% (18 false-positive results), respectively. False-positive cultures for CDBB were attributable to the growth of anaerobic non-
C. difficile
organisms that did not grow in CDBB-TC. Our results suggest that CDBB-TC provides a sensitive and selective medium for the recovery of
C. difficile
organisms from environmental samples, without the need for anaerobic culture conditions.
Whooping cough in school age children presenting with persistent cough in UK primary care after introduction of the preschool pertussis booster vaccination: prospective cohort study
Authors: Wang Kay , Fry Norman K , Campbell Helen , Amirthalingam Gayatri , Harrison Timothy G , Mant David , Harnden Anthony
Published: June 2014

Objective
To estimate the prevalence and clinical severity of whooping cough (pertussis) in school age children presenting with persistent cough in primary care since the introduction and implementation of the preschool pertussis booster vaccination.

Design
Prospective cohort study (November 2010 to December 2012).

Setting
General practices in Thames Valley, UK.

Participants
279 children aged 5 to 15 years who presented in primary care with a persistent cough of two to eight weeks’ duration. Exclusion criteria were cough likely to be caused by a serious underlying medical condition, known immunodeficiency or immunocompromise, participation in another clinical research study, and preschool pertussis booster vaccination received less than one year previously.

Main outcome measures
Evidence of recent pertussis infection based on an oral fluid anti-pertussis toxin IgG titre of at least 70 arbitrary units. Cough frequency was measured in six children with laboratory confirmed pertussis.

Results
56 (20%, 95% confidence interval 16% to 25%) children had evidence of recent pertussis infection, including 39 (18%, 13% to 24%) of 215 children who had been fully vaccinated. The risk of pertussis was more than three times higher (21/53; 40%, 26% to 54%) in children who had received the preschool pertussis booster vaccination seven years or more previously than in those who had received it less than seven years previously (20/171; 12%, 7% to 17%). The risk of pertussis was similar between children who received five and three component preschool pertussis booster vaccines (risk ratio for five component vaccine 1.14, 0.64 to 2.03). Four of six children in whom cough frequency was measured coughed more than 400 times in 24 hours.

Conclusions
Pertussis can still be found in a fifth of school age children who present in primary care with persistent cough and can cause clinically significant cough in fully vaccinated children. These findings will help to inform consideration of the need for an adolescent pertussis booster vaccination in the United Kingdom.

Study registration
UK Clinical Research Network portfolio ID 8361.
Circadian clock desynchronisation and metabolic syndrome
Authors: Sheikh-Ali Mae , Maharaj Jaisri
Published: June 2014

There is emerging evidence in the literature to suggest that disruption of the normal circadian rhythm (sleep–wake cycle signalling) is a potential risk factor to explain the increased incidence of metabolic syndrome. Over the last century, obesity, diabetes and other components of metabolic syndrome have been on the rise. On the other hand, the amount of sleep has decreased from an average of 6–8 h per night. Furthermore, the quality of sleep has declined with more individuals voluntarily decreasing their amount of sleep to work or enjoy leisure activities. Over the last decade, researchers have examined the relationship between disruption in human circadian system and the emergence of symptoms related to metabolic syndrome. Indeed, epidemiological studies suggest a relation between sleep duration and diabetes and obesity. Moreover, experimental animal and human studies suggest such a relation. These studies propose optimum sleep duration of 7–8 h per night to avoid circadian rhythm disruption and suggest that sleep disturbance, whether iatrogenic or disease-related, should be considered as a risk factor for metabolic syndrome, and be addressed. This field is in its infancy and further understanding of specific pathophysiological pathways of circadian desynchronisation will help in developing novel preventive and therapeutic strategies.
Anaesthetic management and complications of pacemaker implantation in dogs
Authors: Sanchis‐Mora S. , Viscasillas J. , Mathis A. , Palacios C. , Brodbelt D. C. , Alibhai H. I.
Published: June 2014

The aim of this study was to report the anaesthetic management and peri‐anaesthetic complications of 57 dogs undergoing pacemaker implantation at a referral institution over 10 years (2002–2012). The median duration of the procedure was 135 minutes (range 25–260 minutes). Patients were classified as American Society of Anaesthesiologist (ASA) III (42 cases) and ASA IV (15 cases). Forty‐three patients had third‐degree atrioventricular block, and 14 patients had sick sinus syndrome. The anaesthetic protocol most frequently chosen was pethidine (41 cases), etomidate‐midazolam (43 cases) and isoflurane in oxygen for maintenance (57 cases). Transthoracic external pacing was used (43 cases) until the internal pacing lead was implanted. Atracurium was administered (48 cases) and intermittent positive pressure ventilation was applied in 52 cases. Complications observed included hypothermia (19 cases) and hypotension (5 cases). Three patients died (5.8%, 95% CI 1.1% to 14.6%) within the first 48 hours after termination of anaesthesia. The outcome for this procedure in sick animals appeared generally good though a number of complications were documented.
Consequences of fish stocking density in a recreational fishery
Authors: Hunt Taylor L. , Giri Khageswor , Brown Paul , Ingram Brett A. , Jones Paul L. , Laurenson Laurie J.B. , Wallis Anne M.
Published: June 2014

Density-dependent processes resulting from fish stocking were demonstrated to have a significant impact on recreational fishery performance, and this case study will be of use to guide fish stocking decisions in other fisheries. We evaluated a put-grow-and-take lake fishery stocking program for Chinook salmon (Oncorhynchus tshawytscha) located in south-western Victoria, Australia. We hypothesised that recreational fishery performance would show significant density-dependent relationships with fish stocking. To test this hypothesis, we used Wald F tests in a general linear regression model to evaluate relationships between a long-term historical fish stocking program and fishery performance, including angler and net catch rates and weight, length, and condition of caught fish. Our results yielded (i) significant positive relationships between angler and net catch rate of Chinook salmon with the number of Chinook salmon stocked in the same year and (ii) significant negative relationships between the weight of angler-caught Chinook salmon with both the number of Chinook salmon stocked in the same year and total number of fish stocked (apart from Chinook salmon) over the previous three year period.
Yb-substituted clathratesBa8-xYbxGa16Ge30
Authors: Liu L. H. , Wei Y. P. , Yang S. W. , Zhu J. , Li Y.
Published: June 2014

Exploration of new rare-earth captured clathrates is an important field of clathrate application. Study on the second phases produced in the synthesis process is crucial for confirming the incorporation of rare earth atoms into the clathrate lattice. In the current study, the Yb -doped clathrate samples with nominal composition of Ba6Yb2Ga16Ge30were prepared by combining arc melting (ARC), melt spinning (MS) and spark plasma sintering (SPS) techniques. By using the TEM with EDS analysis and X-ray diffraction refinement, phase analysis was systemically performed in different steps of the preparation process. Although the clathrate was the main phase in obtained samples, the Yb content in the clathrate phase was found to be much lower than the nominal composition as the Yb atoms strongly tend to create other byproduct phases including Yb2O3— which is the main obstacle in the synthesis of Yb -substituted clathrates. For the dilute Yb -doped germanium clathrate sample a decrease in the thermal conductivity and electrical conductivity was simultaneously observed, therefore, no expected improvement of ZT occurred.
Sequences of Periodic Solutions and Infinitely Many Coexisting Attractors in the Border-Collision Normal Form
Authors: Simpson David J. W.
Published: June 2014

The border-collision normal form is a piecewise-linear continuous map on ℝN that describes the dynamics near border-collision bifurcations of nonsmooth maps. This paper studies a codimension-three scenario at which the border-collision normal form with N = 2 exhibits infinitely many attracting periodic solutions. In this scenario there is a saddle-type periodic solution with branches of stable and unstable manifolds that are coincident, and an infinite sequence of attracting periodic solutions that converges to an orbit homoclinic to the saddle-type solution. Several important features of the scenario are shown to be universal, and three examples are given. For one of these examples, infinite coexistence is proved directly by explicitly computing periodic solutions in the infinite sequence.