bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and Prediction of Centrifugal Compressor Axial Forces During Surge—Part I: Surge Force Measurements
Authors: Brun Klaus , Simons Sarah , Kurz Rainer , Munari Enrico , Morini Mirko , Pinelli Michele
Published: August 2017

Centrifugal compressor impellers and shafts are subject to severe fluctuating axial and radial forces when operating in surge. These forces can cause severe damage to the close clearance components of a centrifugal compressor such as the thrust and radial bearings, interstage and dry gas seals, and balance piston. Being able to accurately quantify the cyclic surge forces on the close clearance components of the compressor allows the user to determine whether an accidental surge event, or emergency shutdown (ESD) transient, has caused damage requiring inspection, repair, or part replacement. For the test, a 700 hp (∼520 kW) industrial air centrifugal compressor was operated in surge at speeds ranging from 7000 to 13,000 rpm and pressure ratios from 1.2 to 1.8. The axial surge forces were directly measured using axial load cells on the thrust bearings. Suction and discharge pressures, proximity probe axial shaft position, flows, and temperatures were also measured. Time domain and frequency plots of axial vibration and dynamic pulsations showed the impact of the operating conditions on surge force amplitudes and frequencies. A surge severity coefficient was also derived as a simple screening tool to evaluate the magnitude of potential damage to a compressor during surge.
Evaluation of Property Methods for Modeling Direct-Supercritical CO2 Power Cycles
Authors: White Charles W. , Weiland Nathan T.
Published: August 2017

Direct supercritical carbon dioxide (sCO2) power cycles are an efficient and potentially cost-effective method of capturing CO2 from fossil-fueled power plants. These cycles combust natural gas or syngas with oxygen in a high pressure (200–300 bar), heavily diluted sCO2 environment. The cycle thermal efficiency is significantly impacted by the proximity of the operating conditions to the CO2 critical point (31 °C, 73.7 bar) as well as to the level of working fluid dilution by minor components, thus it is crucial to correctly model the appropriate thermophysical properties of these sCO2 mixtures. These properties are also important for determining how water is removed from the cycle and for accurate modeling of the heat exchange within the recuperator. This paper presents a quantitative evaluation of ten different property methods that can be used for modeling direct sCO2 cycles in Aspen Plus®. Reference fluid thermodynamic and transport properties (REFPROP) is used as the de facto standard for analyzing high-purity indirect sCO2 systems, however, the addition of impurities due to the open nature of the direct sCO2 cycle introduces uncertainty to the REFPROP predictions as well as species that REFPROP cannot model. Consequently, a series of comparative analyses were performed to identify the best physical property method for use in Aspen Plus® for direct-fired sCO2 cycles. These property methods are assessed against several mixture property measurements and offer a relative comparison to the accuracy obtained with REFPROP. The Lee–Kessler–Plocker equation of state (EOS) is recommended if REFPROP cannot be used.
Rotordynamic Performance of Hybrid Air Foil Bearings With Regulated Hydrostatic Injection
Authors: Yazdi Behzad Zamanian , Kim Daejong
Published: August 2017

Air foil bearing (AFB) technology has made substantial advancement during the past decades and found its applications in various small turbomachinery. However, rotordynamic instability, friction and drag during the start/stop, and thermal management are still challenges for further application of the technology. Hybrid air foil bearing (HAFB), utilizing hydrostatic injection of externally pressurized air into the bearing clearance, is one of the technology advancements to the conventional AFB. Previous studies on HAFBs demonstrate the enhancement in the load capacity at low speeds, reduction or elimination of the friction and wear during starts/stops, and enhanced heat dissipation capability. In this paper, the benefit of the HAFB is further explored to enhance the rotordynamic stability by employing a controlled hydrostatic injection. This paper presents the analytical and experimental evaluation of the rotordynamic performance of a rotor supported by two three-pad HAFBs with the controlled hydrostatic injection, which utilizes the injections at particular locations to control eccentricity and attitude angle. The simulations in both time domain orbit simulations and frequency-domain modal analyses indicate a substantial improvement of the rotor-bearing performance. The simulation results were verified in a high-speed test rig (maximum speed of 70,000 rpm). Experimental results agree with simulations in suppressing the subsynchronous vibrations but with a large discrepancy in the magnitude of the subsynchronous vibrations, which is a result of the limitation of the current modeling approach. However, both simulations and experiments clearly demonstrate the effectiveness of the controlled hydrostatic injection on improving the rotordynamic performance of AFB.
Modeling of Laminar-Turbulent Transition in Boundary Layers and Rough Turbine Blades
Authors: Wei Liang , Ge Xuan , George Jacob , Durbin Paul
Published: August 2017

A local, intermittency-function-based transition model was developed for the prediction of laminar-turbulent transitional flows with freestream turbulence intensity Tu at low (Tu < 1%), moderate (1% < Tu < 3%), and high Tu > 3% levels, and roughness effects in a broad range of industrial applications such as turbine and helicopter rotor blades, and in nature. There are many mechanisms (natural or bypass) that lead to transition. Surface roughness due to harsh working conditions could have great influence on transition. Accurately predicting both the onset location and length of transition has been persistently difficult. The current model is coupled with the k–ω Reynolds-averaged Navier–Stokes (RANS) model, that can be used for general computational fluid dynamics (CFD) purpose. It was validated on the ERCOFTAC experimental zero-pressure-gradient smooth flat plate boundary layer with both low and high leading-edge freestream turbulence intensities. Skin friction profiles agree well with the experimental data. The model was then tested on ERCOFTAC experimental flat plate boundary layer with favorable/adverse pressure gradients cases, periodic wakes, and flows over Stripf's turbine blades with roughness from hydraulically smooth to fully rough. The predicted skin friction and heat transfer properties by the current model agree well with the published experimental and numerical data.
A General Macroscopic Model for Turbulent Flow in Porous Media
Authors: Jouybari Nima F. , Maerefat Mehdi , Staffan Lundström T. , Nimvari Majid E. , Gholami Zahra
Published: August 2017

The present study deals with the generalization of a macroscopic turbulence model in porous media using a capillary model. The additional source terms associated with the production and dissipation of turbulent kinetic energy due to the presence of solid matrix are calculated using the capillary model. The present model does not require any prior pore scale simulation of turbulent flow in a specific porous geometry in order to close the macroscopic turbulence equations. Validation of the results in packed beds, periodic arrangement of square cylinders, synthetic foams, and longitudinal flows such as pipes, channels, and rod bundles against available data in the literature reveals the ability of the present model in predicting turbulent flow characteristics in different types of porous media. Transition to the fully turbulent regime in porous media and different approaches to treat this phenomenon are also discussed in the present study. Finally, the general model is modified so that it can be applied to lower Reynolds numbers below the range of fully turbulent regime in porous media.
An Experimental and Numerical Analysis of Water Hammer Phenomenon in Slurries
Authors: Kodura Apoloniusz , Stefanek Paweł , Weinerowska-Bords Katarzyna
Published: August 2017

Fine solid materials can be transported with the use of water as a carrier liquid. From the practical point of view, the economy of designing and maintenance is usually the most important factor. That way of transport has a lot of advantages for many industry processes. However, the problems of pressure flow are more complicated for slurries than for liquids. The transient flow is one of the most difficult problems to describe. A deep analysis of transients in slurries is crucial, both theoretically and practically. In this paper, the analysis of the transient flow in high-density polyethylene pressure pipelines is described. At the first stage, a laboratory model was build. Experiments made for different volume concentrations were performed. The results were used to build a numerical model of transient flow, which was the second stage of investigation. Due to relatively difficult description of the volumetric concentration bottom layer depth, these parameters vary in time and volume of slurry, and an alternative approach was proposed. The equivalent density was introduced to express the unknown parameters. Performed numerical simulations lead to promising results. In all analyzed episodes, the calculated pressure characteristics demonstrated satisfactory coincidence with observations.
Lift-Generation and Moving-Wall Flow Control Over a Low Aspect Ratio Airfoil
Authors: Amin Boukenkoul Mohammed , Li Feng-Chen , Chen Wen-Li , Zhang Hong-Na
Published: August 2017

Despite the big interest in both, micro-air vehicles (MAV) and flow-control strategies, only few studies have investigated the flow-control possibilities over low aspect ratio (LAR) wings flying at low Reynolds numbers (Re). The present study verified the LAR thick airfoils' conformity with the nonlinear lift approximation equation. Then, a moving-wall flow control method was designed and tested over an LAR thick airfoil (0.57 aspect ration (AR), NACA0015 shaped) performing at a chord-based Re of 4 × 104. The moving belt control postponed the stall onset by 25 deg and produced a 103% gain in lift without any saturation signs at a control speed ratio of Ub/U = 6. Particle image velocimetry (PIV) measurements confirmed the effectiveness of the moving-wall control strategy on the upper surface flow reattachment. Moreover, other quantities such as the, vortices, and the swirling strength are investigated.
An Analysis of Common Drill Stem Vibration Models
Authors: Al Dushaishi Mohammed F. , Nygaard Runar , Stutts Daniel S.
Published: August 2017

Excessive drill stem (DS) vibration while rotary drilling of oil and gas wells causes damages to drill bits and bottom hole assemblies (BHAs). In an attempt to mitigate DS vibrations, theoretical modeling of DS dynamics is used to predict severe vibration conditions. To construct the model, decisions have to be made on which beam theory to be used, how to implement forces acting on the DS, and the geometry of the DS. The objective of this paper is to emphasize the effect of these assumptions on DS vibration behavior under different, yet realistic, drilling conditions. The nonlinear equations of motion were obtained using Hamilton's principle and discretized using the finite element method. The finite element formulations were verified with uncoupled analytical models. A parametric study showed that increasing the weight on bit (WOB) and the drill pipe (DP) length clearly decreases the DS frequencies. However, extending the drill collar length does not reveal a clear trend in the resulting lateral vibration frequency behavior. At normal operating conditions with a low operating rotational speed, less than 80 RPM, the nonlinear Euler–Bernoulli and Timoshenko models give comparable results. At higher rotational speeds, the models deliver different outcomes. Considering only the BHA overestimates the DS critical operating speed; thus, the entire DS has to be considered to determine the critical RPM values to be avoided.
Meta-Atom Molecular Dynamics for Studying Material Property Dependent Deformation Mechanisms of Alloys
Authors: Wang Peng , Wang Hongtao
Published: August 2017

Massively parallel molecular dynamics (MD) simulations have been performed to understand the plastic deformation of metals. However, the intricate interplay between the deformation mechanisms and the various material properties is largely unknown in alloy systems for the limited available interatomic potentials. We adopt the meta-atom method proposed by Wang et al., which unifies MD simulations of both pure metals and alloys in the framework of the embedded atom method (EAM). Owing to the universality of EAM for metallic systems, meta-atom potentials can fit properties of different classes of alloys. Meta-atom potentials for both aluminum bronzes and hypothetic face-centered-cubic (FCC) metals have been formulated to study the parametric dependence of deformation mechanisms, which captures the essence of competitions between dislocation motion and twinning or cleavage. Moreover, the solid-solution strengthening effect can be simply accounted by introducing a scaling factor in the meta-atom method. As the computational power enlarges, this method can extend the capability of massively parallel MD simulations in understanding the mechanical behaviors of alloys. The calculation of macroscopic measurable quantities for engineering oriented alloys is expected to be possible in this way, shedding light on constructing materials with specific mechanical properties.
The Influences of CO2 Injection Pressure on CO2 Dispersion and the Mechanism of CO2–CH4 Displacement in Shale
Authors: Du Xidong , Gu Min , Duan Shuo , Xian Xuefu
Published: August 2017

The effects of CO2 injection pressure (PCO2) on CO2 dispersion and the mechanism of CO2–CH4 displacement in a shale sampled from Changning of China were studied. Results indicated that Coats–Smith dispersion–capacitance model gave a reasonable simulated result to the breakthrough curves of CO2 under different injection pressures. The shapes of CO2 breakthrough curves became more asymmetrical with the increase of CO2 injection pressure. A higher CO2 injection pressure caused early CO2 breakthrough and reduced the recovery of CH4 at CO2 breakthrough (Rpipeline-CH4), but improved the ultimate displaced CH4 amount (Rultimate-CH4). With the increase of CO2 injection pressure, dispersion coefficient (Kd) increased nearly exponentially. A larger Kd led to a lower Rpipeline-CH4 and a longer transition zone. With the increase of CO2 injection pressure, the flowing fraction (F) in pore space decreased nearly linearly and more CO2 diffused into stagnant region to replace adsorbed CH4 in a shale, which resulted in a larger Rultimate-CH4. The mass transfer coefficient (Km) between the flowing and stagnant regions increased with the increase of CO2 injection pressure, which led to a smaller F and larger Rultimate-CH4. CO2 diffusion provided major contribution to CO2 dispersion at lower injection pressure, and mechanical mixing of CO2–CH4 offered predominant contribution to CO2 dispersion at higher injection pressure. Larger mechanical mixing accelerated the mixing of CO2–CH4, which was unfavorable for Rpipeline-CH4. Lower CO2 injection pressure was conductive to gain higher Rpipeline-CH4.
Thermodynamic Properties of Pure and Mixed Thermal Plasmas Over a Wide Range of Temperature and Pressure
Authors: Askari Omid
Published: August 2017

Chemical composition and thermodynamics properties of different thermal plasmas are calculated in a wide range of temperatures (300–100,000 K) and pressures (10−6–100 atm). The calculation is performed in dissociation and ionization temperature ranges using statistical thermodynamic modeling. The thermodynamic properties considered in this study are enthalpy, entropy, Gibbs free energy, specific heat at constant pressure, specific heat ratio, speed of sound, mean molar mass, and degree of ionization. The calculations have been done for seven pure plasmas such as hydrogen, helium, carbon, nitrogen, oxygen, neon, and argon. In this study, the Debye–Huckel cutoff criterion in conjunction with the Griem’s self-consistent model is applied for terminating the electronic partition function series and to calculate the reduction of the ionization potential. The Rydberg and Ritz extrapolation laws have been used for energy levels which are not observed in tabulated data. Two different methods called complete chemical equilibrium and progressive methods are presented to find the composition of available species. The calculated pure plasma properties are then presented as functions of temperature and pressure, in terms of a new set of thermodynamically self-consistent correlations for efficient use in computational fluid dynamic (CFD) simulations. The results have been shown excellent agreement with literature. The results from pure plasmas as a reliable reference source in conjunction with an alternative method are then used to calculate the thermodynamic properties of any arbitrary plasma mixtures (mixed plasmas) having elemental atoms of H, He, C, N, O, Ne, and Ar in their chemical structure.
Molecular modeling to predict peptide accessibility for peptide-functionalized hydrogels
Authors: Li Xianfeng , Jia Jia , Mei Ying , Latour Robert A.
Published: August 2017

Peptide-functionalized (PF) hydrogels are being widely investigated by the tissue engineering and regenerative medicine communities for a broad range of applications because of their unique potential to mimic the natural extracellular matrix and promote tissue regeneration. In order for these complex material systems to perform their intended bioactive function (e.g., cell signaling), the peptides that are tethered to the hydrogel matrix must be accessible at the hydrogel surface for cell–receptor binding. The factors influencing the surface accessibility of the tethered peptide mainly include the length of the tethers, the loading (i.e., concentration) of the peptide, and the association between the tethered peptide and the hydrogel matrix. In the present work, the authors developed coarse-grained molecular models based on the all-atom polymer consistent force field for a type of poly(ethylene glycol)-based PF hydrogel and conducted molecular simulations to investigate the distribution of the peptide within the hydrogel and its surface accessibility as a function of tether length and peptide concentration. The calculated results of the effects of these design parameters on the surface accessibility of the peptide agree very well with corresponding experimental measurements in which peptide accessibility was quantified by the number of cells attached to the hydrogel surface per unit area. The developed modeling methods are able to provide unique insights into the molecular behavior of PF hydrogels and the distribution of the tethered peptides, which can serve as a guide for hydrogel design optimization.
The gravitational self-interaction of the Earth's tidal bulge
Authors: Norsen Travis , Dreese Mackenzie , West Christopher
Published: August 2017

According to a standard, idealized analysis, the Moon would produce a 54 cm equilibrium tidal bulge in the Earth's oceans. This analysis omits many factors (beyond the scope of the simple idealized model) that dramatically influence the actual height and timing of the tides at different locations, but it is nevertheless an important foundation for more detailed studies. Here, we show that the standard analysis also omits another factor—the gravitational interaction of the tidal bulge with itself—which is entirely compatible with the simple, idealized equilibrium model and which produces a surprisingly non-trivial correction to the predicted size of the tidal bulge. Our analysis uses ideas and techniques that are familiar from electrostatics, and should thus be of interest to teachers and students of undergraduate E&M, Classical Mechanics (and/or other courses that cover the tides), and geophysics courses that cover the closely related topic of Earth's equatorial bulge.
On the definition of the time evolution operator for time-independent Hamiltonians in non-relativistic quantum mechanics
Authors: Amaku Marcos , Coutinho Francisco A. B. , Masafumi Toyama F.
Published: August 2017

The usual definition of the time evolution operator e−iHt/ℏ=∑n=0∞1n!(−iℏHt)n, where H is the Hamiltonian of the system, as given in almost every book on quantum mechanics, causes problems in some situations. The operators that appear in quantum mechanics are either bounded or unbounded. Unbounded operators are not defined for all the vectors (wave functions) of the Hilbert space of the system; when applied to some states, they give a non-normalizable state. Therefore, if H is an unbounded operator, the definition in terms of the power series expansion does not make sense because it may diverge or result in a non-normalizable wave function. In this article, we explain why this is so and suggest, as an alternative, another definition used by mathematicians.
Interference between source-free radiation and radiation from sources: Particle-like behavior for classical radiation
Authors: Boyer Timothy H.
Published: August 2017

A simple junior-level electrodynamics problem is used to illustrate the interference between a source-free standing plane wave and a wave generated by a pulse in a current sheet. Depending upon the relative phases between the standing wave and the current pulse and also upon the relative magnitudes, we can find quite different patterns of emitted energy and momentum. If the source gives a large radiation pulse so that the source-free plane wave can be neglected, then the radiation spreads out symmetrically on either side of the current sheet. However, if the radiation sheet gives a pulse with fields comparable to those of the standing wave, then we can find a single radiation pulse moving to the right while the current sheet recoils to the left or the situation with the directions reversed. The example is a crude illustration of particle-like behavior arising from conventional classical electromagnetic behavior in the presence of source-free radiation. The discussion makes contact with the ideas of photons in modern physics.
Transient finite element/equivalent sources using direct coupling and treating the acoustic coupling matrix as sparse
Authors: Fahnline John B. , Shepherd Micah R.
Published: August 2017

Transient structural-acoustic problems can be solved using time stepping procedures with the structure and fluid modeled using finite elements and equivalent sources, respectively. Limitations on the time step size for stable solutions have led to the current popularity of iterative coupling to enforce the boundary conditions at the fluid-structure interface, which also helps to alleviate difficulties caused by the fully populated acoustic coupling matrix. The research presented here examines a monolithic approach using a stabilized equivalent source formulation where the acoustic coupling matrix is either fully diagonal or treated as sparse. In theory, the matrix should be sparse because it relates nodal velocities to nodal acoustic pressure forces during a single time step, and the pressure waves can only travel a distance equal to the sound speed multiplied by the time step. The numerical results demonstrate that for the chosen example problems accurate results are obtained for either diagonal coupling matrices or with a large percentage of the terms set to zero. It is also demonstrated that the formulation adapts well to parallel processing environments and that the times associated with the equivalent source computations are proportional to the number of processors.
“Spot” call: A common sound from an unidentified great whale in Australian temperate waters
Authors: Ward Rhianne , Gavrilov Alexander N. , McCauley Robert D.
Published: August 2017

Underwater passive acoustic recordings in the Southern and Indian Oceans off Australia from 2002 to 2016 have regularly captured a tonal signal of about 10 s duration at 22–28 Hz with a symmetrical bell-shaped envelope. The sound is often accompanied by short, higher frequency downsweeps and repeated at irregular intervals varying from 120 to 200 s. It is termed the “spot” call according to its appearance in spectrograms of long-time averaging. Although similar to the first part of an Antarctic blue whale Z-call, evidence suggests the call is produced by another great whale, with the source as yet not identified.
The turbulent cascade in five dimensions
Authors: Cardesa José I. , Vela-Martín Alberto , Jiménez Javier
Published: August 2017

Tackling the life and death of whirls

Energy in a turbulent system moves from large eddies to smaller ones until it is dissipated by viscous motion. The details of exactly how this works have remained obscure, in part because of the challenge of simulating fluids across many length scales in three dimensions over time. Cardesa
et al.
present a large numeric simulation of a water-like fluid that shows characteristic length scales for the birth and death of turbulent whirls. The approach can be extended to understand energy transfer in the atmosphere, plasmas, and other complex systems.

Science
, this issue p.
782
Mutations in the promoter of the telomerase gene
TERT
contribute to tumorigenesis by a two-step mechanism
Authors: Chiba Kunitoshi , Lorbeer Franziska K. , Shain A. Hunter , McSwiggen David T. , Schruf Eva , Oh Areum , Ryu Jekwan , Darzacq Xavier , Bastian Boris C. , Hockemeyer Dirk
Published: August 2017

Two-step role for mutant
TERT
promoters

Telomeres preserve genomic stability by preventing chromosomal fusions. The recent discovery that human tumors harbor mutations in the promoter region of the telomerase gene (
TERT
) produced a flurry of research aimed at elucidating the role of these mutations in cancer development. Chiba
et al.
present data that reconcile many of the conflicting results reported to date (see the Perspective by Shay). In human melanoma samples and a fibroblast model,
TERT
promoter mutations acted in two steps. First, the mutations allowed cells to proliferate with short telomeres. This fueled genomic instability and up-regulation of telomerase expression, leading to uncontrolled cell proliferation.

Science
, this issue p.
1416
; see also p.
1358
Draft Genome Sequences of Two Gammaproteobacterial Methanotrophs Isolated from Rice Ecosystems
Authors: Frindte Katharina , Kalyuzhnaya Marina G. , Bringel Françoise , Dunfield Peter F. , Jetten Mike S. M. , Khmelenina Valentina N. , Klotz Martin G. , Murrell J. Colin , Op den Camp Huub J. M. , Sakai Yasuyoshi , Semrau Jeremy D. , Shapiro Nicole , DiSpirito Alan A. , Stein Lisa Y. , Svenning Mette M. , Trotsenko Yuri A. , Vuilleumier Stéphane , Woyke Tanja , Knief Claudia
Published: August 2017

The genomes of the aerobic methanotrophs “
Methyloterricola oryzae
” strain 73a
T
and
Methylomagnum ishizawai
strain 175 were sequenced. Both strains were isolated from rice plants.
Methyloterricola oryzae
strain 73a
T
represents the first isolate of rice paddy cluster I, and strain 175 is the second representative of the recently described genus
Methylomagnum
.
Draft Genome Sequences of Escherichia coli O104 Strains of Bovine and Human Origin
Authors: Shridhar Pragathi B. , Patel Isha R. , Gangiredla Jayanthi , Mammel Mark K. , Noll Lance , Shi Xiaorong , Bai Jianfa , Elkins Christopher A. , Strockbine Nancy , Nagaraja T. G.
Published: August 2017

Cattle harbor and shed in their feces several
Escherichia coli
O104 serotypes. All O104 strains examined were intimin negative and belonged to the B1 phylogroup, and some were Shiga toxigenic. We report here the genome sequences of bovine O104:H7 (
n
= 5), O104:H23 (
n
= 2), O104:H8 (
n
= 1), and O104:H12 (
n
= 1) isolates and human clinical isolates of O104:H7 (
n
= 5).
Genome Sequences of Five Multidrug-Resistant Escherichia coli Sequence Type 117 Isolates Recovered from Dairy Calves
Authors: Kim Seon-Woo , Karns Jeffrey S. , Van Kessel Jo Ann S. , Haley Bradd J.
Published: August 2017

Escherichia coli
sequence type 117 (ST117) strains have been recovered from poultry with colibacillosis, as well as from urinary tract infections and fatal septic infections in humans. To further investigate ST117 isolates recovered from nonpoultry food animals, we sequenced the genomes of five ST117 isolates from dairy calves in Pennsylvania.
Complete Genome Sequence of Pseudoalteromonas piscicida Strain DE2-B, a Bacterium with Broad Inhibitory Activity toward Human and Fish Pathogens
Authors: Richards Gary P. , Needleman David S. , Watson Michael A.
Published: August 2017

Pseudoalteromonas piscicida
strain DE2-B is a halophilic bacterium which has broad inhibitory activity toward vibrios and other human and fish pathogens. We report the first closed genome sequence for this species, which consists of two chromosomes (4,128,210 and 1,188,838 bp). Annotation revealed multiple genes encoding proteases with potential antibacterial properties.
Draft Genome Sequences of Two Unclassified
Chitinophagaceae
Bacteria, IBVUCB1 and IBVUCB2, Isolated from Environmental Samples
Authors: Orr Russell J. S. , Rombauts Stephane , Van de Peer Yves , Shalchian-Tabrizi Kamran
Published: August 2017

We report here the draft genome sequences of two
Chitinophagaceae
bacteria, IBVUCB1 and IBVUCB2, assembled from metagenomes of surface samples from freshwater lakes. The genomes are >99% complete and may represent new genera within the
Chitinophagaceae
family, indicating a larger diversity than currently identified.
Genome Sequence of an Australian Monophasic Salmonella enterica subsp.
enterica
Typhimurium Isolate (TW-Stm6) Carrying a Large Plasmid with Multiple Antimicrobial Resistance Genes
Authors: Dyall-Smith Mike L. , Liu Yuhong , Billman-Jacobe Helen
Published: August 2017

We report the genome sequence of a monophasic
Salmonella enterica
subsp
. enterica
Typhimurium strain (TW-Stm6) isolated in Australia that is similar to epidemic multidrug-resistant strains from Europe and elsewhere. This strain carries additional antibiotic and heavy-metal resistance genes on a large (275-kb) IncHI2 plasmid.
Draft Genome Sequence of a Clinical Isolate of Streptococcus mutans Strain HM
Authors: Kondo Yoshio , Nishimata Haruka , Hidaka Kiyoshi , Hasuwa Tomoyuki , Moriuchi Hiroyuki , Fujiwara Taku , Hoshino Tomonori
Published: August 2017

We report the draft genome sequence of
Streptococcus mutans
strain HM isolated from a 4-year-old girl with infective endocarditis. The genomics information will provide information on the genetic diversity and virulence potential of
S. mutans
strain HM.
Complete Genome Sequence of Enterobacter cloacae 704SK10, an OXA-48-Encoding Wastewater Isolate
Authors: Marti Roger , Stephan Roger , Klumpp Jochen , Nüesch-Inderbinen Magdalena , Hummerjohann Jörg , Bagutti Claudia , Zurfluh Katrin
Published: August 2017

Here we present the complete genome sequence of
Enterobacter cloacae
704SK10, a Swiss wastewater isolate encoding an OXA-48 carbapenemase. Assembly resulted in closed sequences of the 4,876,946-bp chromosome, a 111,184-bp IncF plasmid, and an OXA-48-encoding IncL plasmid (63,458 bp) nearly identical to the previously described plasmid pOXA-48.
Six Key Traits of Fungi: Their Evolutionary Origins and Genetic Bases
Authors: Nagy László G. , Tóth Renáta , Kiss Enikő , Slot Jason , Gácser Attila , Kovács Gábor M.
Published: August 2017

The fungal lineage is one of the three large eukaryotic lineages that dominate terrestrial ecosystems. They share a common ancestor with animals in the eukaryotic supergroup Opisthokonta and have a deeper common ancestry with plants, yet several phenotypes, such as morphological, physiological, or nutritional traits, make them unique among all living organisms. This article provides an overview of some of the most important fungal traits, how they evolve, and what major genes and gene families contribute to their development. The traits highlighted here represent just a sample of the characteristics that have evolved in fungi, including polarized multicellular growth, fruiting body development, dimorphism, secondary metabolism, wood decay, and mycorrhizae. However, a great number of other important traits also underlie the evolution of the taxonomically and phenotypically hyperdiverse fungal kingdom, which could fill up a volume on its own. After reviewing the evolution of these six well-studied traits in fungi, we discuss how the recurrent evolution of phenotypic similarity, that is, convergent evolution in the broad sense, has shaped their phylogenetic distribution in extant species.
Accuracy of 11 formulae to guide umbilical arterial catheter tip placement in newborn infants
Authors: Lean Wei Ling , Dawson Jennifer A , Davis Peter G , Theda Christiane , Thio Marta
Published: August 2017

Background

Umbilical arterial catheter (UAC) insertion is a common procedure in the neonatal intensive care unit (NICU). Correct placement of the tip of the UAC at first attempt minimises handling of the infant and reduces the risk of infection and complications. We aimed to determine the accuracy of 11 published formulae to guide UAC placement.

Methods

This was a one-year prospective observational study in a tertiary NICU. Clinicians used their preferred formula for UAC insertion, with X-rays performed immediately post-procedure to check the tip position. Birth weight and measurements included in the 11 formulae were recorded within 48 hours. The gold standard insertion distance was defined as the distance from the abdominal wall to the mid-descending aorta, at T8 level on X-ray (range T6–T10). Insertion length using the 11 formulae was calculated and compared with this gold standard distance.

Results

One hundred and three infants were included, with median (IQR) gestational age and weight of 28 (26–33.5) weeks and 980 (780–2045) g, respectively. The predicted value of the 11 formulae to place the UAC in correct position ranged from 51.0% to 73.8%. Formulae that involved direct body part measurements showed the highest predicted success rates, smallest mean difference from T8 and narrowest limits of agreement using the Bland-Altman method.

Conclusion

Success rates for accurate UAC placement are highest when formulae that involve body measurements are used. However, even the most accurate method would result in more than 25% of UACs needing manipulation to achieve an optimal position.
Hypersegmented neutrophils and oval macrocytes in the setting of B12deficiency and pancytopaenia
Authors: Farrelly Sean James , O’Connor Kieran Anthony
Published: August 2017

Vitamin B12deficiency is a recognised pathology in several populations, with a particular prevalence in an older adult population. We present two cases whereby vitamin B12deficiency is the causative factor in marked pancytopaenia. Oval macrocytosis and hypersegmented neutrophils were noted on both peripheral blood samples, which are a characteristic finding in macrocytic anaemia due to B12deficiency. Distinct underlying pathologies were identified in both cases; food-cobalamin malabsorption and pernicious anaemia. Parenteral vitamin B12supplementation resulted in a marked reticulocytosis and rapid improvement of haematological indices in both cases. We present this series to serve as a reminder that B12deficiency can present as life-threatening pancytopaenia.It has has multiple underlying pathologies,defined risk populations and has characteristic blood film findings which can guide investigations, diagnosis and treatment.
Discitis andClostridium perfringensbacteraemia
Authors: Yong Chen Han , Lam Miranda
Published: August 2017

The authors present a case involving an 80-year-old man with infectious T10/T11 discitis on the background of a recentClostridium perfringensbacteraemia. This case report describes a case of probableC. perfringensdiscitis as further investigations failed to identify any causative agents. He was treated with intravenous piperacillin/tazobactam to good effect, achieving favourable clinical outcome. Diagnosis of discitis/osteomyelitis can often be delayed and mismanaged due to its non-specific presentations. Timing of empirical antimicrobial therapy requires careful consideration based on haemodynamic stability and neurological function to maximise microbiological yield.
Assessing the use of BreatheSmart® mobile technology in adult patients with asthma: a remote observational study
Authors: Melvin Emilie , Cushing Anna , Tam Anne , Kitada Ruri , Manice Melissa
Published: August 2017

Introduction

Non-adherence to asthma daily controller medications is a common problem, reported to be responsible for 60% of asthma-related hospitalisations. The mean level of adherence for asthma medications is estimated to be as low as 22%. Therefore, objective measurements of adherence to medicine are necessary. This virtual observational study is designed to measure the usability of an electronic monitoring device platform that measures adherence. Understanding how patients use the BreatheSmart mobile technology at home is essential to assess its feasibility as a solution to improve medication adherence. We anticipate this approach can be applied to real-world environments as a cost-effective solution to improve medication adherence.

Methods and analysis

This is a virtual 6-month observational study of 100 adults (≥18 years) with an asthma diagnosis, using inhaled corticosteroids for at least 3 months. Participants will be recruited in the USA through ad placements online. All participants receive wireless Bluetooth-enabled inhaler sensors that track medication usage and an mSpirometerTMcapable of clinical-grade lung function measurements, and download the BreatheSmart mobile application that transmits data to a secure server. All analyses are based on an intention-to-treat. Usability is assessed by patient questionnaires and question sessions. Simple paired t-test is used to assess significant change in Asthma Control Test score, quality of life (EuroQol-5D questionnaire) and lung function.

Ethics and dissemination

No ethical or safety concerns pertain to the collection of these data. Results of this research are planned to be published as soon as available.

Trial registration number

NCT03103880.
Managing diabetes at high altitude: personal experience with support from a Multidisciplinary Physical Activity and Diabetes Clinic
Authors: Malcolm Gary , Rilstone Sian , Sivasubramaniyam Sivasujan , Jairam Carol , Chew Stephen , Oliver Nick , Hill Neil E
Published: August 2017

Objective

Physical activity is important for well-being but can be challenging for people with diabetes. Data informing support of specialist activities such as climbing and high-altitude trekking are limited. A 42-year-old man with type 1 diabetes (duration 30 years) attended a Multidisciplinary Physical Activity and Diabetes Clinic planning to climb Mont Blanc during the summer and trek to Everest Base Camp in the autumn. His aims were to complete these adventures without his diabetes impacting on their success.

Methods

We report the information provided that enabled him to safely facilitate his objectives, in particular, the requirement for frequent checking of blood glucose levels, the effects of altitude on insulin dose requirements, and recognition that acute mountain sickness may mimic the symptoms of hypoglycaemia and vice versa. Real-time continuous glucose monitoring was made available for his treks.

Results

The effects of high altitude on blood glucose results and glycaemic variability while treated on multiple daily injections of insulin are reported. In addition, we present a first-person account of his experience and lessons learnt from managing diabetes at high altitude.

Conclusions

A dedicated Multidisciplinary Physical Activity and Diabetes Clinic delivering individualised, evidence-based, patient-focused advice on the effects of altitude on blood glucose levels, and provision of real-time continuous glucose monitoring enabled uneventful completion of a trek to Everest Base Camp in a person with type 1 diabetes.
A study of intensity, fatigue and precision in two specific interval trainings in young tennis players: high-intensity interval training versus intermittent interval training
Authors: Suárez Rodríguez David , del Valle Soto Miguel
Published: August 2017

Background

The aim of this study is to find the differences between two specific interval exercises. We begin with the hypothesis that the use of microintervals of work and rest allow for greater intensity of play and a reduction in fatigue.

Methods

Thirteen competition-level male tennis players took part in two interval training exercises comprising nine 2 min series, which consisted of hitting the ball with cross-court forehand and backhand shots, behind the service box. One was a high-intensity interval training (HIIT), made up of periods of continuous work lasting 2 min, and the other was intermittent interval training (IIT), this time with intermittent 2 min intervals, alternating periods of work with rest periods. Average heart rate (HR) and lactate levels were registered in order to observe the physiological intensity of the two exercises, along with the Borg Scale results for perceived exertion and the number of shots and errors in order to determine the intensity achieved and the degree of fatigue throughout the exercise.

Results

There were no significant differences in the average heart rate, lactate or the Borg Scale. Significant differences were registered, on the other hand, with a greater number of shots in the first two HIIT series (series 1 p>0.009; series 2 p>0.056), but not in the third. The number of errors was significantly lower in all the IIT series (series 1 p<0.035; series 2 p<0.010; series 3 p<0.001).

Conclusion

Our study suggests that high-intensity intermittent training allows for greater intensity of play in relation to the real time spent on the exercise, reduced fatigue levels and the maintaining of greater precision in specific tennis-related exercises.
USPSTF is unable to recommend for or against lipid screening to identify multifactorial dyslipidaemia in childhood: no recommendation is not without consequences
Authors: de Ferranti Sarah D , Sheldrick Radley C
Published: August 2017

Paediatric lipid screening has been recommended for decades to identify youth at increased risk for early atherosclerotic disease but is controversial and not universally adopted. A 2016 review by the US Preventive Services Task Force (USPSTF) found inadequate evidence to recommend for or against lipid screening in childhood. In this Perspective article, we examine this controversial and important topic more broadly. We consider whether the USPSTF framework is asking the right questions, and whether the answers to these questions should be valued equally, whether the USPSTF questions are answerable and by what types of evidence and whether the burden of proof is appropriate. We argue that using a broader framework that includes the magnitude of potential benefits and harms, considering more types of evidence beyond randomised controlled trials, and more fully incorporating patient and parent perspectives could lead to more practical and more widely applicable guidance for practitioners, guide future research priorities and be more inclusive of patient priorities.
Adjuvant treatment of anogenital warts with systemic interferon: a systematic review and meta-analysis
Authors: Westfechtel Lukas , Werner Ricardo Niklas , Dressler Corinna , Gaskins Matthew , Nast Alexander
Published: August 2017

Background

Interferons are natural messenger proteins that are used to treat various disease entities. Due to their immunomodulating, antiviral and antiproliferative effects, the systemic administration of interferons after ablative treatment for anogenital warts (AGWs) has been advocated to increase clearance and decrease recurrence rates. However, studies investigating the efficacy of adjuvant systemic interferon have yielded inconsistent results. The objective of this systematic review and meta-analysis was to comprehensively assess and evaluate the available evidence from randomised controlled trials.

Methods

A literature search was conducted in Cochrane Central Register of Controlled Trials, Embase and MEDLINE. Available data were classified according to the interferon type and dosage. Pooled effect estimates were calculated for predefined outcomes. The Cochrane Collaboration’s risk of bias tool was used to assess the included trials and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to evaluate our confidence in the effect estimates.

Results

Twelve trials were identified that met the inclusion criteria and assessed immunocompetent patients with external AGW. Compared with placebo, adjuvant alpha-, beta- and gamma-interferon were generally not significantly superior in terms of complete clearance over the short, intermediate or long term, nor with regard to intermediate- or long-term recurrence. However, the low-dose subgroup of adjuvant alpha-interferon was significantly superior compared with placebo regarding intermediate-term complete clearance and recurrence. Further data were available for the comparison of different dosages of alpha- and beta-interferon and for comparisons of the three interferon types. No significant differences were seen in these comparisons regarding efficacy. Data on quality of life were not available.

Conclusions

The GRADE quality of the evidence ranged from ‘very low’ to ‘high’. The significantly higher efficacy of low-dose alpha-interferon compared with placebo was based on a single trial, and our confidence in the effect estimates rated as ‘low’. Overall, we found no reliable evidence favouring the systemic use of interferon after ablative treatment of AGW.
British Veterinary Association Annual General Meeting Belfast, September 21, 2017
Authors: Thorpe D.
Published: August 2017

The 2017 Annual General Meeting of the British Veterinary Association will be held at W5 at Odyssey, 2 Queen's Quay, Belfast, Antrim, on Thursday, September 21, 2017, at 15.50.
A rigorous method for three-dimensional asymmetrical slope stability analysis
Authors: Jiang Qinghui , Zhou Chuangbing
Published: August 2017

Most slope failures exhibit remarkable asymmetrical variation in the transverse direction. A rigorous method satisfying all six equilibrium conditions is proposed for evaluating three-dimensional (3-D) asymmetrical slope stability. As there is no need to predefine a symmetrical plane in this analysis, the method is applicable to slopes with complex geometries, geologies, and loading conditions. The proposed method can not only calculate the factor of safety, but also predict the direction of sliding of the potential failure mass. Global equilibrium equations are formulated in light of the safety factor, sliding direction, and an assumed distribution of normal stress on the slip surface. The Newton method is then used to solve these equations, which has been proven to enjoy both a large range of convergence and a fast convergence rate. Thereafter, physical admissibility conditions of the solutions, and the effects of the size of discretized columns on solution accuracy, are discussed in the present 3-D analysis. The method is validated by using five typical examples documented in the literature. The failure of the Kettleman, California, waste landfill slope is also re-evaluated using the proposed method. The calculated stability and direction of sliding match field observations.