bluuebunny/crossref_metadata_2025 huggingface dataset:
Generator Collector Brush Holder Testing and Design Improvements
Authors: Steinbach Albert E. , Scalzo Frank A. , Preston Matthew T.
Published: November 2016

Electric generators and synchronous motors with static excitation use rotating slip rings (also known as collector rings) and stationary carbon brushes to transfer the field current from the stationary exciter to the rotating generator field. The carbon brushes experience wear from both mechanical friction and electrical contact with the rings. Therefore, the brushes need to be periodically inspected and replaced. This is often the most frequent maintenance activity for an electric generator. It is generally recognized that if brushes are not changed when worn down, this can result in a damaging condition called a flashover that will usually force the generator offline. Several collector flashovers were investigated to look for other common characteristics with the aim of reducing the risk of flashover occurrence and improving generator reliability. Some features of the generator collector brush holders were identified as significant contributors to collector flashovers and also to other, more common maintenance problems. Several brush holder designs were evaluated with regard to these features and also with regard to feedback received from operators. In addition, an in-house test rig was developed and used to compare multiple, existing brush holder designs and new prototype concepts for brush wear rate and current selectivity. This work led to a new brush holder design that addresses these concerns and has subsequently been successfully tested in a laboratory and at a customer site. That new brush holder design is being applied to both new units and as a retrofit to in-service aftermarket generators.
Discrete Element Studies of Gravity-Driven Dense Granular Flows in Vertical Cylindrical Tubes
Authors: Chilamkurti Yesaswi N. , Gould Richard D.
Published: November 2016

The current paper focusses on the characterization of gravity-driven dry granular flows in cylindrical tubes. With a motive of using dense particulate media as heat transfer fluids (HTF), the main focus was to address the characteristics of flow regimes with a packing fraction of ∼60%. In a previous work [1], experimental and computational studies were conducted to understand the effects of different geometrical parameters on the flow physics. The current paper is an extension of that work to gain more insights into the granular flow physics. The three-dimensional computer simulations were conducted by implementing the Discrete Element Method (DEM) for the Lagrangian modelling of particles. Hertz-Mindilin models were used for the soft-particle formulations of inter-particulate contacts. Simulations were conducted to examine the particulate velocities and flow rates to understand the rheology in the dense flow regime. Past studies suggested the existence of a Gaussian mean velocity profile for dense gravity-driven granular flows. These observations were further analyzed by studying the influence of geometrical parameters on the same. The current work thus focusses on studying the rheology of dense granular flows and obtaining a better understanding of the velocity profiles, the wall friction characteristics, and the particle-wall contact behavior.
Energy Efficiency Increase in Cement Industry Through Implementation of Up and Bottoming Cogeneration Cycles
Authors: Soles Agamez Cristian Camilo , Corredor Lesmes
Published: November 2016

Cement industry consumes high energy levels with 4GJ per ton produced in average, 30% of it being electric and 70% thermal [1]. Cogeneration in this type of processes is not widespread; for only a few efforts have been made worldwide to implement methods that take advantage of waste heat stream, given that these contain 36% of the thermal input energy required to produce electricity [2]. Furthermore the implementation of a power generation alternative to feed limestone’s calcinations process is suggested.

This paper is focused on the evaluation of thermal energy recovery strategies through the implementation of cogeneration systems, enabling an increase in efficiency and profitability producing electricity in before and after-processes of the cement production process. This will be achieved using methods of computer analysis implementing the ASPEN HYSIS™ software to simulate the behavior of the systems taking the rotary kiln operating conditions as main input or output variables.

For the implementation of the system two important steps furnace operation will be taken. First one, related to combustion, is performed to produce the energy required in limestone’s processing entering this system, at this point the commercial gas turbine is used, coupled to a generator subsequently taking the power of oxygen-rich flow at the exhaust which is at a high temperature allowing a post-combustion using an afterburner.

Finally, a second stage is evaluated at the downstream of the kiln, where a flow of charged waste gases counts with enough energy to perform an additional phase of power generation using an organic Rakine cycle (ORC).
Aero Structure Interaction for Mechanical Integration of Laced LP Compressor Blades in a Gas Engine Rotor
Authors: Nagarajaiah Vinayaka , Banerjee Nilotpal , Ajay Kumar B. S. , Gowda Kumar K.
Published: November 2016

Aero-structure interaction during turbomachinery blade design has become an important area of research due to its critical applications in aero engines and land based gas turbines. Studies reveal that a certain mistuning leads to stress build up through mode localization under operating conditions. This paper deals with comparative case studies of aero-structure interaction for free standing and various laced LP blade configurations of a gas turbine. The lacing wire provides better structural integrity as it is more aerodynamic and feasible when compared to cases of free standing blades without lacing wires. Hence calling for the optimum positioning checks at ¼th, ½, ¾th and combined positioning at ¼th and ¾th along the length of LP compressor blades. The lacing wire of both circular and elliptical cross sections are considered for comparative study for better aerodynamic performance. Assuming 100% fixity at blade root, the study involves critical parametric evaluations involved in achieving mechanical integrity in airfoil design and blade platform design. Mechanical integrity involves stress checks, frequency margins, Campbell Diagram, gross yield stress, Stress Stiffening and Spin Softening of blades and so on, for design and off-design conditions for a given stage efficiency of 93% in an ideal LP compressor of a gas turbine engine.
Transient Stress Analysis and High Cycle Fatigue Life Estimation of a Gas Turbine Shrouded HP Compressor Blade
Authors: Nagarajaiah Vinayaka , Banerjee Nilotpal , Ajay Kumar B. S. , Gowda Kumar K. , Dalappa Tulsidas
Published: November 2016

This work is focused on developing a technique to assess high cycle fatigue of shrouded HP compressor blades subjected to thermo-mechanical loads like centrifugal stresses, vibratory stresses and thermal stresses in a gas turbine rotor. In practice, the blades are also subjected to resonance condition during steady or transient conditions of operation when passing through critical speeds. Hence, shrouds are added initially at 3/4 length along blade height which helps in reducing vibration amplitude by providing suitable stiffness to the blade and hence better structural integrity. Industrial best practice like Campbell diagram is used for the above purpose. Two approaches employed here for fatigue analysis are linear Finite element analysis (FEA) and Elasto-Plastic FEA. Fictive elastic results are recalculated using Neuber’s Rule. Strain amplitude approach is followed and Coffin-Manson Equation is used to determine the number of start-up and shut-down cycles. Design and analysis is performed using ANSYS 14.5 tool for reliable fatigue life estimation and to predict catastrophic failure due to High Cycle Fatigue.
Comparisons of Aqueous Surfactant Solutions for Nucleate Pool Boiling
Authors: Dikici Birce , Al-Sukaini Basim Q. A.
Published: November 2016

In this study, nucleate pool boiling of surfactant solutions are investigated. The surfactants chosen for the study are an ionic sodium lauryl sulfate (SLS), nonionic ECOSURF™ EH-14, and nonionic ECOSURF™ SA-9. It is observed that adding a small amount of surfactant alters the water boiling phenomenon considerably. Boiling curves for different concentrations are shifted to the left. The wall temperature dropped with an increase in the concentration of aqueous surfactant solutions. Also, it is found that the boiling heat transfer enhancement of SLS is higher than that of EH-14 and SA-9 compared to water. Boiling heat transfer coefficient (h) enhancements compared to water are 46%, 30%, and 21%. (for SLS, for EH-14 and for SA-9 respectively)

Boiling visualization shows that boiling with surfactant solutions compared with that in pure water is more vigorous. Bubbles are smaller, activate continuously, and collapse quickly. Also, the bubble departure frequency is observed to be higher than that of pure water.

Results prove that there is an important possibility to enhance the boiling application processes by environmentally friendly EH-14, and SA-9 additives. Experimentation can be extended for searching other surfactants in order to find their most efficient quantity in water for boiling heat transfer.
Design of a Partial Admission Turbine for an Organic Rankine Cycle With Environmental Fluctuation Consideration
Authors: Heshmat Hooshang , Hunsberger Andrew , Walton James F.
Published: November 2016

This paper describes the design and testing of a high-efficiency turbo-generator for use in an Organic Rankine Cycles (ORC) with a power target of 30–100 kWe. The elegant yet simple design consists of a hermetically sealed, single piece rotor, with axial turbine and permanent magnet generator. The design employs compliant foil bearings (CFB), which eliminate the need for any external lubricates or dynamic seals and no contamination risk to the process fluid. A unique partial admission turbine concept is employed which provides better than 80% efficiency across a wide range of seasonal temperature variation, such as those occurring in northern latitudes, where summers can be hot (> 35°C) and humid and winters are extremely cold (< −20°C) and dry. We describe the design and prototype manufacturing as it pertains to micro and meso-scale turbines (< 100 kW) in terms of thermodynamic cycle considerations, turbine design, rotor-bearing dynamics, overall system design and scale-up considerations.
Numerical Modeling and Simulation of Injection Cooling and Wet Gas Compression
Authors: Kishor Shyam
Published: November 2016

This paper presents application of Computational Fluid Dynamics (CFD) in modeling wet gas compression in a multiphase compressor, where liquid is injected inside the compression chamber to enhance cooling and achieve near isothermal compression.

CFD is used for detailed flow field and heat transfer analysis. It includes 3D transient simulations of multiphase compressible turbulent flow. During each cycle, compression and suction chambers keep moving and deforming. Computational domains include a gate that separates compression chamber from the suction chamber. Gate moves up and down to always remain in contact with the rotor. A custom program is used to prescribe motion for the moving and deforming domain.

Eulerian-Lagrangian method is used to model continuous and discrete (atomized droplets) phases and their interaction. Droplet dynamics under the influence of turbulence, acceleration, diffusion and body forces are studied. Models to capture droplet breakup and coalescence are included. Results from CFD simulations are used to optimize compressor performance.

Temperature and pressure variations during the compression cycle are presented. Most of the pressure and temperature rise occurs towards the end of the compression cycle. Atomization details including droplets trajectory, droplet size distribution and droplet velocity variations are presented. Temperature distribution inside the compression chamber is used to optimize location, size, and flow rate of liquid injections.
Heat Transfer Characteristics of Subcooled Water Flow Boiling in Circular Channels With Non-Uniform Heating Fluxes
Authors: Zhu Ge , Bi Qincheng , Yan Jianguo , Yuan Qizheng , Lv Haicai , Pan Hui
Published: November 2016

Experiments of heat transfer characteristics of subcooled water flowing in vertical circular channels, which were off-center in rectangular blocks, were carried out under high heat fluxes up to the ITER requirements. The heating flux distributions of the channels were non-uniform in the circumferential direction, which were obtained by electrically heating the blocks directly. Two types of channels were used: smooth channel and twisted tapes channel. The surface temperature of the rectangular blocks was measured by infrared camera and thermocouples. Effect of the system pressure, mass flow rate, inlet subcooling, and equivalent heat fluxes on heat transfer were all investigated. The main attention was paid to the subcooled water heat transfer under non-uniform heating flux, and the effect of twisted tapes. Results show that subcooled boiling is more likely to become the dominant factor under the conditions of lower mass flow rates, higher heat fluxes and lower system pressures. Twisted tapes can enhance the heat transfer, which is more evident in high heat fluxes. The temperature fields in the block were calculated with a Computational Fluid Dynamics (CFD) method to obtain, which were consistent with the experimental results.
Experimental Exploration of a Small Scale Pneumatically Pumped Thermal Storage System
Authors: Rodriguez Inri , Cerda Jesus , Codd Daniel S.
Published: November 2016

A prototype water-glycerol two tank storage system was designed to simulate the fluidic properties of a high temperature molten salt system while allowing for room temperature testing of a low cost, small scale pneumatically pumped thermal storage system for use in concentrated solar power (CSP) applications. Pressurized air is metered into a primary heat transfer fluid (HTF) storage tank; the airflow displaces the HTF through a 3D printed prototype thermoplate receiver and into a secondary storage tank to be dispatched in order to drive a heat engine during peak demand times. A microcontroller was programmed to use pulse-width modulation (PWM) to regulate air flow via an air solenoid. At a constant frequency of 10Hz, it was found that the lowest pressure drops and the slowest flowrates across the receiver occurred at low duty cycles of 15% and 20% and low inlet air pressures of 124 and 207 kPa. However, the data also suggested the possibility of slug flow. Replacement equipment and design modifications are suggested for further analysis and high temperature experiments. Nevertheless, testing demonstrated the feasibility of pneumatic pumping for small systems.
Investigation of Flame Height From Multiple Liquefied Natural Gas Fire
Authors: Ho T. C. , Fu S. C. , Chao Christopher Y. H.
Published: November 2016

The research of multiple liquefied natural gas fires is limited due to the unique condition of temperature and velocity. Therefore, the effect of the distance between multiple liquefied natural gas jet fires on the characteristics of the flame is investigated by numerical methods in this paper. Grid analyses have been carried out to establish sufficient resolution of the grid and to ensure the domain size is appropriate for jet fire cases. The temperature, velocity and concentration of the reactant inside the fire were calculated, and the shape of the flame was also studied. By changing the distance between the jets, the size and height of the fires are changed. Simulations of jet fires separated by different distances were carried out. Investigation of three discharge velocities (30, 40, 50 m/s) with different separation distances (0–28 m) were done. When the jets were close enough fires were observed to merge and were enhanced due to interaction. Both the flame height and the temperature increased. When the jets were separated by a significant distance, the flame height returned to the height of a single jet fire. The distance effect of multiple jet fires was investigated and reported in this paper.
Research on Flow-Induced Energy Harvesting by Flexible Piezoelectric Plate With Upstream Square Cylinder
Authors: Zhang Li , Yang Zesheng , Ding Lin , Chen Yanrong
Published: November 2016

The study on energy harvesting by flow-induced motion has attracted a widespread concern. The representative energy harvesters are electromagnetic energy converter and piezoelectric power generator. The traditional electromagnetic energy converter cannot work well in low speed fluid. However, the piezoelectric power generator has a great advantage in that case. This paper implemented wind tunnel test for square cylinder-piezoelectric plate structure, thus to obtain the characteristics of energy output of piezoelectric plate at different wind speeds. The results show that in the case of low speed wind, the velocity has obvious effect on the output voltage of the piezoelectric plate. With the increase of the wind speed, the deformation of the piezoelectric plate and the output voltage increases rapidly. When the wind speed is high, the output voltage of the tail will produce more harmonic, and the harmonic may reduce the quality of output voltage. We need to select the appropriate wind speed to improve the power quality.
Code Compliance in a Rapidly Changing Industry: Data Centers and the Development of BSR/ASHRAE Standard 90.4P
Authors: Comperchio Dan , Behere Sameer
Published: November 2016

The data center industry has seen a rapid expansion in the last few years, causing a lapse in the ability for codes to react quickly enough. As new, innovative designs emerge to handle specialized applications, increased rack densities and wider thermal operating condition envelopes, system designs are also evolving with increasing frequency. Data center developers and designers are taking lessons learned from regional, national or even international sites and applying the best practices to new designs. In a three to six year code cycle, designs can become obsolete and outdated before a revised code is even adopted. This is especially pronounced in regards to the energy code adopted by the majority of the states where considerable controversy broke out over the applicability of prescriptive methodologies in the prominent ANSI/ASHRAE/IES Standard 90.1-2010 with regards to data centers. The result was a bifurcation within the organization and a specialized committee was tasked with developing a parallel standard with the intentions of codifying requirements specific to data centers. At the time of this writing, the committee is still developing BSR/ASHRAE Standard 90.4P which carves out data center designs from the general commercial building energy code and apply data center-centric requirements culled from an active industry group and extensive public review comment periods. Navigating the new standard can be difficult, however the proper interpretation and understanding of it is critical to the ongoing success of data center operations.
Verification and Validation of CFD Model to Predict Jet Loads and Blast Wave Pressures From High Pressure Superheated Steam Line Break
Authors: Pal S. , Iek C. , Peltier L. J. , Smirnov A. , Knight K. J. , Zheng D. , Jarvis J.
Published: November 2016

High pressure superheated or saturated steam line breaks in a nuclear power plant generate high speed jet flows and blast waves. The jet loads and blast wave pressures can damage critical nuclear power plant components. An accurate assessment of these effects including uncertainty quantification (UQ), is essential to confirm that design is robust enough to handle jet flows and blast waves from postulated steam line breaks. This paper presents the verification and validation of a computational model created using a commercial CFD code for making such assessments. The verification and validation process involves the steps of application space parametrization, Phenomena Identification and Ranking (PIR), CFD model lockdown, selection of validation dataset, and calculation of formal validation metrics. The Uncertainty Quantification in the actual application should include the propagated validation uncertainties from the validation test problems.
Obligatory role for GPER in cardiovascular aging and disease
Authors: Meyer Matthias R. , Fredette Natalie C. , Daniel Christoph , Sharma Geetanjali , Amann Kerstin , Arterburn Jeffrey B. , Barton Matthias , Prossnitz Eric R.
Published: November 2016

The G protein–coupled receptor GPER promotes hypertension and aging-induced tissue damage through reactive oxygen species.
Competitive Growth Enhances Conditional Growth Mutant Sensitivity to Antibiotics and Exposes a Two-Component System as an Emerging Antibacterial Target in Burkholderia cenocepacia
Authors: Gislason April S. , Choy Matthew , Bloodworth Ruhi A. M. , Qu Wubin , Stietz Maria S. , Li Xuan , Zhang Chenggang , Cardona Silvia T.
Published: November 2016

Chemogenetic approaches to profile an antibiotic mode of action are based on detecting differential sensitivities of engineered bacterial strains in which the antibacterial target (usually encoded by an essential gene) or an associated process is regulated. We previously developed an essential-gene knockdown mutant library in the multidrug-resistant
Burkholderia cenocepacia
by transposon delivery of a rhamnose-inducible promoter. In this work, we used Illumina sequencing of multiplex-PCR-amplified transposon junctions to track individual mutants during pooled growth in the presence of antibiotics. We found that competition from nontarget mutants magnified the hypersensitivity of a clone underexpressing
gyrB
to novobiocin by 8-fold compared with hypersensitivity measured during clonal growth. Additional profiling of various antibiotics against a pilot library representing most categories of essential genes revealed a two-component system with unknown function, which, upon depletion of the response regulator, sensitized
B. cenocepacia
to novobiocin, ciprofloxacin, tetracycline, chloramphenicol, kanamycin, meropenem, and carbonyl cyanide 3-chlorophenylhydrazone, but not to colistin, hydrogen peroxide, and dimethyl sulfoxide. We named the gene cluster
esaSR
for
e
nhanced
s
ensitivity to
a
ntibiotics
s
ensor and
r
esponse regulator. Mutational analysis and efflux activity assays revealed that while
esaS
is not essential and is involved in antibiotic-induced efflux,
esaR
is an essential gene and regulates efflux independently of antibiotic-mediated induction. Furthermore, microscopic analysis of cells stained with propidium iodide provided evidence that depletion of EsaR has a profound effect on the integrity of cell membranes. In summary, we unraveled a previously uncharacterized two-component system that can be targeted to reduce antibiotic resistance in
B. cenocepacia
.
Population Pharmacokinetics and Pharmacogenetics Analysis of Rilpivirine in HIV-1-Infected Individuals
Authors: Aouri Manel , Barcelo Catalina , Guidi Monia , Rotger Margalida , Cavassini Matthias , Hizrel Cédric , Buclin Thierry , Decosterd Laurent A. , Csajka Chantal ,   the Swiss HIV Cohort Study
Published: November 2016

Rilpivirine (RPV), the latest nonnucleoside reverse transcriptase inhibitor active against HIV-1, is prescribed in a standard dosage of 25 mg once a day in combination with emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF). The aim of this observational study was to characterize the RPV pharmacokinetic profile, to quantify interpatient variability, and to identify potential factors that could influence drug exposure. RPV concentration data were collected from HIV-infected patients as part of routine therapeutic drug monitoring performed in our center (Laboratory of Clinical Pharmacology). A population pharmacokinetic analysis was performed with NONMEM by comparing various structural models. The influence of demographic and clinical covariates, as well as frequent genetic polymorphisms in 5 genes (
CYP3A4*22
,
CYP3A5*3
,
CYP2C19*2
,
CYP2C19*17
,
UGT1A1*28
, and
UGT1A4*2
), on RPV elimination was explored. A total of 325 plasma concentration measurements were obtained from 249 HIV-positive patients. Plasma concentrations ranged from 12 to 255 ng/ml. A one-compartment model with zero-order absorption best characterized RPV pharmacokinetics. The average RPV clearance (CL) was 11.7 liters/h, the average volume of distribution was 401 liters, and the mean absorption time was 4 h. The interinterindividual variability (IIV) for CL was estimated to be 33%. None of the available demographic or genetic covariates showed any influence on RPV pharmacokinetics, but 29% of the patients were predicted to present minimal concentrations below the recently identified target cutoff value of 50 ng/ml. The variability in RPV pharmacokinetics appears to be lower than that for most other antiretroviral drugs. However, under the standard regimen of 25 mg daily, a significant number of patients might be underdosed. It remains to be investigated whether the underexposure has an impact on the development of resistance while patients are on maintenance therapy.
Morphological Effect of the New Antifungal Agent ME1111 on Hyphal Growth of Trichophyton mentagrophytes, Determined by Scanning and Transmission Electron Microscopy
Authors: Nishiyama Yayoi , Takahata Sho , Abe Shigeru
Published: November 2016

The effects of ME1111, a novel antifungal agent, on the hyphal morphology and ultrastructure of
Trichophyton mentagrophytes
were investigated by using scanning and transmission electron microscopy. Structural changes, such as pit formation and/or depression of the cell surface, and degeneration of intracellular organelles and plasmolysis were observed after treatment with ME1111. Our results suggest that the inhibition of energy production by ME1111 affects the integrity and function of cellular membranes, leading to fungal cell death.
Acinetobacter baumannii Biofilm Formation in Human Serum and Disruption by Gallium
Authors: Runci Federica , Bonchi Carlo , Frangipani Emanuela , Visaggio Daniela , Visca Paolo
Published: November 2016

Biofilm-associated infections caused by
Acinetobacter baumannii
are extremely recalcitrant to antibiotic treatment. We report that
A. baumannii
develops a mature biofilm when grown in complement-free human serum (HS). We demonstrate that 16 μM gallium nitrate (GaN) drastically reduces
A. baumannii
growth and biofilm formation in HS, whereas 64 μM GaN causes massive disruption of preformed
A. baumannii
biofilm. These findings pave the way to the repurposing of GaN as an antibiofilm agent for
A. baumannii
.
Screening and Characterization of a Non-
cyp51A
Mutation in an
Aspergillus fumigatus cox10
Strain Conferring Azole Resistance
Authors: Wei Xiaolei , Chen Peiying , Gao Rongsui , Li Yeqi , Zhang Anxue , Liu Feifei , Lu Ling
Published: November 2016

The rapid and global emergence of azole resistance in the human pathogen
Aspergillus fumigatus
has drawn attention. Thus, a thorough understanding of its mechanisms of drug resistance requires extensive exploration. In this study, we found that the loss of the putative calcium-dependent protein-encoding gene
algA
causes an increased frequency of azole-resistant
A. fumigatus
isolates. In contrast to previously identified azole-resistant isolates related to
cyp51A
mutations, only one isolate carries a point mutation in
cyp51A
(F219L mutation) among 105 independent stable azole-resistant isolates. Through next-generation sequencing (NGS), we successfully identified a new mutation (R243Q substitution) conferring azole resistance in the putative
A. fumigatus
farnesyltransferase Cox10 (AfCox10) (AFUB_065450). High-performance liquid chromatography (HPLC) analysis verified that the decreased absorption of itraconazole in related
Afcox10
mutants is the primary reason for itraconazole resistance. Moreover, a complementation experiment by reengineering the mutation in a parental wild-type background strain demonstrated that both the F219L and R243Q mutations contribute to itraconazole resistance in an
algA
-independent manner. These data collectively suggest that the loss of
algA
results in an increased frequency of azole-resistant isolates with a non-
cyp51A
mutation. Our findings indicate that there are many unexplored non-
cyp51A
mutations conferring azole resistance in
A. fumigatus
and that
algA
defects make it possible to isolate drug-resistant alleles. In addition, our study suggests that genome-wide sequencing combined with alignment comparison analysis is an efficient approach to identify the contribution of single nucleotide polymorphism (SNP) diversity to drug resistance.
SecA—a New Twist in the Tale
Authors: Collinson Ian
Published: November 2016

A paper published in this issue of the
Journal of Bacteriology
(D. Huber, M. Jamshad, R. Hanmer, D. Schibich, K. Döring, I. Marcomini, G. Kramer, and B. Bukau, J Bacteriol 199:e0622-16, 2017,
https://doi.org/10.1128/JB.00622-16
) provides us with a timely reminder that all is not as clear as we had previously thought in the general bacterial secretion system. The paper describes a new mode of secretion through the Sec system—“uncoupled cotranslocation”—for the passage of proteins across the bacterial inner membrane and suggests that we might rethink the nature and mechanism of the targeting and transport steps toward protein export.
Disconnected pancreatic duct syndrome: a multidisciplinary management dilemma
Authors: Alsaad Ali A , Dhannoon Sarah M , Phillips Michael B
Published: November 2016

Disconnected pancreatic duct syndrome is a circumferential interruption of the pancreatic duct. It usually occurs secondary to pancreatitis and carries significant diagnostic and management challenges. We present a case of disconnected pancreatic duct syndrome that represented a diagnostic and management dilemma for both medical and surgical teams. The aim of this article is to share a successful management experience of disconnected pancreatic duct syndrome with other physicians and to perform a brief but focused literature review on this challenging condition.
COMPARISON OF LABORATORY DATA AMONG THE SIX DIFFERENT PRP SEPARATION SYSTEMS USING 144 SAMPLES
Authors: Lhee SH , Kim JW , Jeon JB , Lee DY
Published: November 2016

Many systems for preparation of platelet-rich plasma (PRP) are commercially available, but comparative study among these systems is rare and only small sample size studies have been conducted. The purpose of this study was to characterize the platelet, white blood cell (WBC), red blood cell (RBC) concentrations, and CD 34 counts in the PRP produced by six commercially available PRP separation systems, using a single donor model. Twenty-four healthy humans who were not taking medication consented to donate 180 mL of blood. Whole blood samples were collected with appropriate ratio of anticoagulant, and each sample was simultaneously processed by PRP separation systems according to the manufacturer's protocol. Total of 144 samples were collected and analysed. After we obtained quantification of Platelet, WBC, RBC and CD34+ cell enumeration, the difference in mean platelet, WBC, RBC concentration and CD 34 counts among PRP separation systems was analysed. The GPS III (6.5±0.9) produced PRP with highest mean platelet concentration, whereas the Conditioned Plasma (2.0±0.7) and Tubex (2.2±1.0) produced PRP with lowest mean platelet concentration. The GPS III (4.7±0.8) produced PRP with highest mean WBC concentration, whereas the Conditioned Plasma (0.2±0.3) produced PRP with lowest mean WBC concentration. The Conditioned Plasma produced PRP with lowest mean RBC concentration (0.1±0.1). Regarding the collection efficiency of platelet, the Addcell (71.1±28.4) and GPS III (72.2±9.6) produced the highest PRP concentration, whereas the Tubex (26.2±12.0) produced with the lowest PRP concentration. Mean CD 34+ cell count did not differ among six different PRP separation systems. As lots of clinical researches using PRP used different separation systems, with little or no characterization of components of the PRP, this study will provide fundamental data to interpret lots of clinical researches conducted so far. This study will provide an accurate context for physician to interpret the results and thereby make informed decisions about how to use the various PRP separation systems to provide effective PRP treatment in clinical situations.
NON-CONTACT INJURY INCIDENCE AND WARM UP OBSERVATION IN HOCKEY IN SCOTLAND
Authors: Johnston T , Brown S , Kaliarntas K , Taylor C
Published: November 2016

Noncontact injuries occur during manoeuvres such as landing, accelerating and the side-cut. This investigation has assessed the prevalence and manoeuvres associated with noncontact injuries and the current warm up practice. An online questionnaire was utilised to assess injury epidemiology (n=437, males (m)=48%, females (f)=52%) and an observational notational technique was employed to assess warm up practice (n=17, m=7, f=10). The Hockey Injury Questionnaire showed noncontact injuries were sustained by 57% of all players, 80% of which to the lower extremity. The overall frequency of injuries was 5.7 injuries/1000 playing hours. Females were injured more frequently than males (6.6 vs 4.0 injuries per 1000 hours). These injuries were caused by a side-cut (21%) and acceleration (16%) causing injuries to the knee (23%) and hamstring (20%). These injuries were sustained during training (37%) and 3rdquarter (18%). The two most common injuries were muscle strains (29%) and pulled muscles (24%) in males causing no time off (30%) and 2 weeks off (26%). In females, muscle sprains (20%) and ligament sprains (18%) were frequent causing no time off (37%) and to miss the next exposure (16%). The entire warm up lasted 21 min for male teams, 25 mins for females. The warming up aspect lasted for about 15 min (m=14.8 mins, f=14.5 min); the skill rehearsal aspect lasted for about 7 min (m=7 min, f=10 min). The warm ups were mostly devised by qualified coaches (77%). Only one warm up contained proprioceptive exercises. A post warm up questionnaire showed the coaches devised the warm ups were mostly performed as planned (65%). However, 77% of coaches would like to alter the warm up to include injury reduction exercises (n=6), dynamic stretches (n=4) and more time (n=4). This research shows that noncontact injuries are common to the lower extremity and the knee. Over 33% of the injuries occurred in training. Females sustained more noncontact injuries than males despite warming up for a longer. There is a large disparity in the length of the warm up skill rehearsal period and total time. The content, which coaches would like to alter, is largely in the sagittal plane contrary to the playing actions. Therefore, a sport-specific warm up to alter movement patterns and reduce injuries is needed.
Observational study of the safety of buprenorphine+naloxone in pregnancy in a rural and remote population
Authors: Jumah Naana Afua , Edwards Craig , Balfour-Boehm Jazmyn , Loewen Kassandra , Dooley Joseph , Gerber Finn Lianne , Kelly Len
Published: November 2016

Objectives

To describe the effect of in utero exposure to the buprenorphine+naloxone combination product in a rural and remote population.

Setting

A district hospital that services rural and remote, fly-in communities in Northwestern Ontario, Canada.

Participants

A retrospective cohort study was conducted of 855 mother infant dyads between 1 July 2013 and 30 June 2015. Cases included all women who had exposure to buprenorphine+naloxone during pregnancy (n=62). 2 control groups were identified; the first included women with no opioid exposure in pregnancy (n=618) and the second included women with opioid exposure other than buprenorphine+naloxone (n=159). Women were excluded if they had multiple pregnancy or if they were part of a methadone programme (n=16). The majority of women came from Indigenous communities.

Outcomes

The primary outcomes were birth weight, preterm delivery, congenital anomalies and stillbirth. Secondary neonatal outcomes included gestational age at delivery, Apgar scores at 1 and 5 min, NAS Score >7 and treatment for neonatal abstinence syndrome (NAS). Secondary maternal outcomes included the number of caesarean sections, postpartum haemorrhages, out of hospital deliveries and transfer of care to tertiary centres.

Results

No difference was found in the primary outcomes or in the Apgar score and caesarean section rate between in utero buprenorphine+naloxone exposure versus no opioid exposure in pregnancy. Compared to women taking other opioids, women taking buprenorphine+naloxone had higher birthweight babies (p=0.001) and less exposure to marijuana (p<0.001) during pregnancy.

Conclusions

Retrospective data suggest that there likely is no harm from taking buprenorphine+naloxone opioid agonist treatment in pregnancy. Larger, prospective studies are needed to further assess safety.
Individual surgeon mortality rates: can outliers be detected? A national utility analysis
Authors: Harrison Ewen M , Drake Thomas M , O'Neill Stephen , Shaw Catherine A , Garden O James , Wigmore Stephen J
Published: November 2016

Objectives

There is controversy on the proposed benefits of publishing mortality rates for individual surgeons. In some procedures, analysis at the level of an individual surgeon may lack statistical power. The aim was to determine the likelihood that variation in surgeon performance will be detected using published outcome data.

Design

A national analysis surgeon-level mortality rates to calculate the level of power for the reported mortality rate across multiple surgical procedures.

Setting

The UK from 2010 to 2014.

Participants

Surgeons who performed colon cancer resection, oesophagectomy or gastrectomy, elective aortic aneurysm repair, hip replacement, bariatric surgery or thyroidectomy.

Outcomes

The likelihood of detecting an individual with a 30-day, 90-day or in-patient mortality rate of up to 5 times the national mean or median (as available). This was represented using a novel heat-map approach.

Results

Overall mortality rates for the procedures ranged from 0.07% to 4.5% and mean/median surgeon volume was between 23 and 75 cases. The national median case volume for colorectal (n=55) and upper gastrointestinal (n=23) cancer resections provides around 20% power to detect a mortality rate of 3 times the national median, while, for hip replacement, this is a rate 5 times the national average. At the mortality rates reported for thyroid (0.08%) and bariatric (0.07%) procedures, it is unlikely a surgeon would perform a sufficient number of procedures in his/her entire career to stand a good chance of detecting a mortality rate 5 times the national average.

Conclusions

At present, surgeons with increased mortality rates are unlikely to be detected. Performance within an expected mortality rate range cannot be considered reliable evidence of acceptable performance. Alternative approaches should focus on commonly occurring meaningful outcome measures, with infrequent events analysed predominately at the hospital level.
The thermal-like equilibrium universe in f(R) gravity
Authors: Wei Yi-Huan , Zhao Jia-Xin , Cui Xiao
Published: November 2016

Some problems of the thermal-like equilibrium (TLE) universe in f(R) gravity are studied. Given the energy density of the TLE universe, the late-time form of f(R) is obtained. For the TLE universe driven by the non-relativistic matter, the energy of the apparent horizon (AH) and the ratio between it and the energy inside the AH are calculated.
A Parallel Elastoplastic Reanalysis Based on GPU Platform
Authors: He Guanqiang , Wang Hu , Huang Guangxin , Liu Haitao , Li Guangyao
Published: November 2016

An efficient parallel elastoplastic reanalysis method is suggested. The main backbone of the suggested method is based on combined approximation (CA) reanalysis. GPU parallel computation is used to accelerate assembling the stiffness matrix. Assembling process is divided into the offline part for strain matrix and online part for element stiffness matrix, which makes the structure of the program more reasonable and efficient. Pseudo elastic analysis is introduced and extended to load increment method to make the CA method more feasible. The numerical examples show that the suggested method can improve the efficiency of elastoplastic analysis significantly and the accuracy of results can also be ensured.
Shielding STT-RAM Based Register Files on GPUs against Read Disturbance
Authors: Zhang Hang , Chen Xuhao , Xiao Nong , Wang Lei , Liu Fang , Chen Wei , Chen Zhiguang
Published: November 2016

To address the high energy consumption issue of SRAM on GPUs, emerging Spin-Transfer Torque (STT-RAM) memory technology has been intensively studied to build GPU register files for better energy-efficiency, thanks to its benefits of low leakage power, high density, and good scalability. However, STT-RAM suffers from the read disturbance issue, which stems from the fact that the voltage difference between read current and write current becomes smaller as technology scales. The read disturbance leads to high error rates for read operations, which cannot be effectively protected by the SEC-DED ECC on large-capacity register files of GPUs.

Prior schemes (e.g., read-restore) to mitigate the read disturbance usually incur either non-trivial performance loss or excessive energy overhead, thus not applicable for the GPU register file design that aims to achieve both high performance and energy-efficiency. To combat the read disturbance, we propose a novel software-hardware co-designed solution (i.e.,
Red-Shield
), which consists of three optimizations to overcome the limitations of the existing solutions. First, we identify dead reads at compiling stage and augment instructions to avoid unnecessary restores. Second, we employ a small read buffer to accommodate register reads with high-access locality to further reduce restores. Third, we propose an adaptive restore mechanism to selectively pick the suitable restore scheme, according to the busy status of corresponding register banks. Experimental results show that our proposed design can effectively mitigate the performance loss and energy overhead caused by restore operations while still maintaining the reliability of reads.
On the Sequences Realizing Perron and Lyapunov Exponents of Discrete Linear Time-Varying Systems
Authors: Niezabitowski Michał
Published: November 2016

We investigate properties of partial exponents (in particular, the Lyapunov and Perron exponents) of discrete time-varying linear systems. In the set of all increasing sequences of natural numbers, we define an equivalence relation with the property that sequences in the same equivalence class have the same partial exponent. We also define certain subclass of all increasing sequences of natural numbers, including all arithmetic sequences, such that all partial exponents are achievable on a sequence from this class. Finally, we show that the Perron and Lyapunov exponents may be approximated by partial exponents achievable on sequences in certain sense similar to geometric sequences.
Immune Profile of Honduran Schoolchildren with Intestinal Parasites: The Skewed Response against Geohelminths
Authors: Gabrie José Antonio , Rueda María Mercedes , Rodríguez Carol Anahelka , Canales Maritza , Sanchez Ana Lourdes
Published: November 2016

Soil-transmitted helminth infections typically induce a type-2 immune response (Th2), but no immunoepidemiological studies have been undertaken in Honduras, an endemic country where the main control strategy is children’s annual deworming. We aimed to characterize the immune profile of Honduran schoolchildren harbouring these parasitoses. Demographic and epidemiological data were obtained through a survey; nutritional status was assessed through anthropometry; intestinal parasites were diagnosed by formol-ether and Kato-Katz; and blood samples were collected to determine immunological markers including Th1/Th2 cytokines, IgE, and eosinophil levels. A total of 225 children participated in the study, all of whom had received deworming during the national campaign five months prior to the study. Trichuriasis and ascariasis prevalence were 22.2% and 20.4%, respectively. Stunting was associated with both age and trichuriasis, whereas ascariasis was associated with sex and household conditions. Helminth infections were strongly associated with eosinophilia and hyper-IgE as well as with a Th2-polarized response (increased levels of IL-13, IL-10, and IL4/IFN-γratios and decreased levels of IFN-γ). Pathogenic protozoa infections were associated with a Th1 response characterized by elevated levels of IFN-γand decreased IL10/IFN-γratios. Even at low prevalence levels, STH infections affect children’s nutrition and play a polarizing role in their immune system.
Novel Graphical Analyses of Runs of Homozygosity among Species and Livestock Breeds
Authors: Iacolina Laura , Stronen Astrid V. , Pertoldi Cino , Tokarska Małgorzata , Nørgaard Louise S. , Muñoz Joaquin , Kjærsgaard Anders , Ruiz-Gonzalez Aritz , Kamiński Stanisław , Purfield Deirdre C.
Published: October 2016

Runs of homozygosity (ROH), uninterrupted stretches of homozygous genotypes resulting from parents transmitting identical haplotypes to their offspring, have emerged as informative genome-wide estimates of autozygosity (inbreeding). We used genomic profiles based on 698 K single nucleotide polymorphisms (SNPs) from nine breeds of domestic cattle (Bos taurus) and the European bison (Bison bonasus) to investigate how ROH distributions can be compared within and among species. We focused on two length classes: 0.5–15 Mb to investigate ancient events and >15 Mb to address recent events (approximately three generations). For each length class, we chose a few chromosomes with a high number of ROH, calculated the percentage of times a SNP appeared in a ROH, and plotted the results. We selected areas with distinct patterns including regions where (1) all groups revealed an increase or decrease of ROH, (2) bison differed from cattle, (3) one cattle breed or groups of breeds differed (e.g., dairy versus meat cattle). Examination of these regions in the cattle genome showed genes potentially important for natural and human-induced selection, concerning, for example, meat and milk quality, metabolism, growth, and immune function. The comparative methodology presented here permits visual identification of regions of interest for selection, breeding programs, and conservation.
Survival Prediction and Feature Selection in Patients with Breast Cancer Using Support Vector Regression
Authors: Goli Shahrbanoo , Mahjub Hossein , Faradmal Javad , Mashayekhi Hoda , Soltanian Ali-Reza
Published: November 2016

The Support Vector Regression (SVR) model has been broadly used for response prediction. However, few researchers have used SVR for survival analysis. In this study, a new SVR model is proposed and SVR with different kernels and the traditional Cox model are trained. The models are compared based on different performance measures. We also select the best subset of features using three feature selection methods: combination of SVR and statistical tests, univariate feature selection based on concordance index, and recursive feature elimination. The evaluations are performed using available medical datasets and also a Breast Cancer (BC) dataset consisting of 573 patients who visited the Oncology Clinic of Hamadan province in Iran. Results show that, for the BC dataset, survival time can be predicted more accurately by linear SVR than nonlinear SVR. Based on the three feature selection methods, metastasis status, progesterone receptor status, and human epidermal growth factor receptor 2 status are the best features associated to survival. Also, according to the obtained results, performance of linear and nonlinear kernels is comparable. The proposed SVR model performs similar to or slightly better than other models. Also, SVR performs similar to or better than Cox when all features are included in model.