bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and Dynamics of Bounded Vortex Flows With Different Nozzle Heights
Authors: Green A. M. , Marshall J. S.
Published: April 2015

A bounded vortex flow is generated by a nozzle with a central suction outlet surrounded by inlet jets with a 15 deg inclination in the azimuthal direction. The jets impinge on a flat surface called the impingement surface. The circulation introduced by azimuthal tilting of the inlet jets is concentrated at the flow centerline by the suction outlet to form a wall-normal vortex, with axis nominally orthogonal to the impingement surface. An experimental study was conducted in water to examine the structure and dynamics of bounded vortex flows with balanced inlet and outlet flow rates for different values of the separation distance h between the nozzle face and the impingement surface. The experiments used a combination of laser-induced fluorescence (LIF) to visualize the vortex and jet flow structure and particle-image velocimetry (PIV) for quantitative velocity measurements along a planar slice of the flow. Different liquid flow rates were examined for each separation distance. The results show that a stationary wall-normal vortex is formed at small separation distances, such as when the ratio of h to the inlet jet radial position R is set to h/R=0.67. When the separation distance is increased such that h/R=1.3, the intake vortex first becomes asymmetric, drifting to the one side of the flow, and then bifurcates into a vortex pair that rotates in a V-state around the flow centroid. At large separation distances (e.g., h/R=6.7), the intake vortex adopts a spiral structure that is surrounded by the inlet jets, with upward-flowing exterior fluid at the center of the spiral vortex structure. The arms of this spiral are advected downward with time by the inlet jet flow until they reach the impingement surface. Knowledge of this flow structure at different separation distances is necessary in order to design systems that utilize this flow field for enhancement of particle removal rate or heat/mass transfer from a surface.
Low Reynolds Number Flow Characteristics for Two Side by Side Rotating Cylinders
Authors: Supradeepan K. , Roy Arnab
Published: April 2015

Numerical simulations were performed for two-dimensional viscous incompressible flow past two stationary side-by-side rotating circular cylinders at Reynolds number (Re) 100 by varying center-to-center distance between the cylinders from 1.1 to 3.5 times the diameter (D) of a cylinder and different rotational speed ratio (α) = 0.5, 1.0, and 1.25. The incompressible Navier–Stokes equations were solved using consistent flux reconstruction (CFR) technique of Roy and Bandyopadhyay (2006, “A Finite Volume Method for Viscous Incompressible Flows Using a Consistent Flux Reconstruction Scheme,” Int. J. Numer. Methods Fluids, 52(3), pp. 297–319). Eight different flow regimes were observed within the investigated parametric space. An attempt has been made to characterize the different flow regimes using vorticity contours, λ2 criterion, and force coefficients. All these above stated methods confirm the existence of eight different regimes in the flow.
Effect of Trailing-Edge Modification of a Mixed-Flow Pump
Authors: Wu Dazhuan , Yan Peng , Chen Xin , Wu Peng , Yang Shuai
Published: April 2015

Modern pumps are designed to guarantee a sufficiently large operating range or to satisfy the performance requirements relative to more than one operating point. This study applies trailing-edge (TE) modification method based on TE rounding in the suction surface to widen the operating range of a mixed-flow pump. The effects of TE modification on the performance and internal flow of the mixed-flow pump are investigated through computational fluid dynamics (CFD) analysis. Local Euler head distribution is introduced to reveal the pattern of energy growth along the blade-aligned (BA) streamwise location. A pump model with TE modification is tested, and numerical results agree well with experimental data. The results show that TE modification significantly improves pump efficiency in the high flow rate region by more than 10%. The best pattern of normalized local Euler head distribution (NLEHD) is a convex curve of nearly constant growth rate. The overall heads are also improved, and the flow near the exit of the impeller exhibits better uniformity. This finding demonstrates that a small change in the TE of the impeller can influence flow structure in most areas of impeller channels and that the local Euler head distribution is closely related to pump efficiency. TE modification can effectively improve the performance of the mixed-flow pump with high flow rate.
Large-Eddy Simulation of a Mixed-Flow Pump at Off-Design Conditions
Authors: Posa Antonio , Lippolis Antonio , Balaras Elias
Published: April 2015

The flow through turbopumps is characterized by highly unsteady phenomena at part load conditions, involving large separation and generation of vortical structures. This behavior is strongly dependent on the interaction between rotating and steady parts, which is significantly modified, compared to the one at the design flow rate. Therefore, at off-design conditions, eddy-resolving computations are more suitable to analyze the complex physics occurring inside turbomachinery channels. In this work the large eddy simulation (LES), coupled with an immersed-boundary (IB) method, is utilized to study a mixed-flow pump at a reduced flow rate, equivalent to 40% of the nominal one. The present approach has been already validated in a previous study, where a satisfactory agreement with two-dimensional (2D) particle image velocimetry (PIV) experiments has been shown at design conditions. In this paper a comparison with the LES results at the optimal flow rate is also proposed, in order to understand the important modifications of the flow occurring at part loads.
Some Exact Analytical Solutions for Two-Dimensional Flow of an Incompressible Second Grade Fluid
Authors: Ullah Saif
Published: April 2015

This investigation deals with some exact analytical solutions of the incompressible second grade fluid by using the method based on the separation of variables. In many cases, this method can derive exact analytical solutions easier than other methods. A family of solutions is derived in this paper, which governs scientific and engineering experimentations. The derived solutions represent the flows having streamlines as a family of ellipses, parabolas, concentric circles, and rectangular hyperbolas. From practical point of view, these flows have applications in many manufacturing processes in industry. Some physical features of the derived solutions are also illustrated by their contour plots.
The Regenerative Gas Turbine in the Total-Energy Picture
Authors: Roberts W. Stewart
Published: April 2015

An illustration is given of the considerations necessary in the application of a regenerative gas turbine to a total-energy system involving electric power, heating and air conditioning. Performance of the turbine is compared to a nonregenerative type. Requirements of a modern downtown office building based upon actual operating records for the year 1962 are matched against the turbine’s capabilities for supplying the system.
The Mechanics of Bearing Supports
Authors: Bodger W. K.
Published: April 2015

The general problem of flexibility of supports is investigated analytically. It is shown that geometrically symmetric supports are also elastically symmetric, leading to reduced rotor vibration problems. The 90-deg, two-armed support also is shown to be elastically symmetric. Small departures from the 90-deg spacing, however, are shown to lead to serious lack of elastic symmetry. The simple pedestal is shown to be incapable of being designed with elastic symmetry. The symmetric support is shown to induce fewer blade-excitation frequencies in turbomachines.
Starting and Control of a Large Gas Turbine
Authors: Wickstrom B. , Ohquist H.
Published: April 2015

Essential features of peak-load and stand-by gas-turbine plants are rapid starting, small personnel requirements and reliable fast-acting control systems. In designing a gas turbine of 40–50 Mw output, consideration has been given to fulfilling these requirements, thus many special features have been adopted including an air starting device and an electrohydraulic control system for fully automatic starting and operation. Studies have also been made of the effects of rapid load changes on the temperature gradients in the high temperature parts.
FT4A Gas-Turbine Engine for Marine and Industrial Applications
Authors: Carlson C. L.
Published: April 2015

The major design features of the FT4A gas-turbine engine for marine and industrial applications are described, the development-test history of the engine is reviewed, and the field experience with this and similar engine concepts is discussed. In addition, the particular characteristics of the FT4A power plant which make the latter attractive for various applications are mentioned.
Propulsion Machinery of the “Koeln” Class Escort Frigates With Special Consideration of Gas Turbine Propulsion
Authors: Kurzak K. H. , Reuter H.
Published: April 2015

The Koeln Class escort frigates represents the first larger type of vessel built for the German Federal Navy. The design work dates back as far as 1955–1956. In view of the planned operational use of the ships an extremely light construction of the propulsion machinery with a long operating range was required. Furthermore, combat safety required an appropriate space structure of the propulsion machinery. For this purpose various propulsion systems were examined at the time, e.g., steam-turbine and diesel-engine propulsion, and a comparison was made between direct and electrical output transmissions. The advanced development of gas-turbine technique in connection with the introduction of high pressure-charged, high-speed diesel engines together with the development of high-performance, variable-pitch propellers led to a design which, compared with other types of propulsion, proved to be extremely advantageous not only with regard to the standard displacement of the vessel but, because of the low fuel consumption, also to the displacement of the fully equipped ship (1, 2).
The Effect of Reynolds Number on the Performance of a Tangential-Flow Turbine
Authors: Adams Robert G.
Published: April 2015

The tangential-flow turbine, which was developed from the drag turbine in an effort to take advantage of the circulatory flow in the drag-turbine passages, frequently has been proposed for use in power systems characterized by low specific speeds. Since such systems often operate with low exhaust pressures which lead to low Reynolds numbers in turbine passages, it is of interest to determine the effect of Reynolds number on the performance of this type of machine. Theoretical determination of the effect is made difficult by the complex three-dimensional nature of the flow in this type of turbine. This paper describes a program of tests which was run on a tangential-flow turbine to investigate the effect of Reynolds number, and presents a simplified theoretical approach to the Reynolds-number effect which is shown to give a reasonable prediction of the trend of the effect.
The Closed-Cycle Gas Turbine and Cryogenics: A New Application
Authors: La Fleur James
Published: April 2015

A method is described whereby a closed-cycle gas turbine can be used to produce cryogenic refrigeration. This system utilizes a common compressor for both power and refrigeration, thereby reducing initial cost and, hence, making the closed-cycle gas turbine attractive as a prime mover in this field.
The Effect of Reynolds Number on the Performance of Partial Admission and Re-Entry Axial Turbines
Authors: Adams Robert G.
Published: April 2015

In turbines designed for open-cycle auxiliary power systems for orbital and reentry vehicles, turbine blade Reynolds numbers of less than 1000 are not uncommon. An investigation of the effect of Reynolds number in this range on the performance of partial admission and reentry axial turbines, which are the predominant types of turbine used in this class of power system, was recently conducted. This paper describes the test program carried out, the results of the investigation, and examines the implications of the results on the design of turbines for this application. In general, it was found that the drop in efficiency with reduced Reynolds number was not so rapid with the types of turbine studied as with the full-admission turbine. The optimum pressure-ratio split was also found to be significantly affected by the Reynolds numbers encountered in the turbine stages.
Sulfur and Sea Salt Attack of Turbine Blades
Authors: Dalton C. A.
Published: April 2015

Sulfur attack in aero engines and salt attack in marine engines are recurring problems. The effects, mechanism and prevention of sulfur attack in aero engines is discussed. The mechanism for sea salt attack on marine turbine blades is proposed and the results of tests designed to cure the trouble are presented. The treatment suggested is only a palliative and speculation on future work for greater protection is included.
Lifting Fan Noise Studies
Authors: Krishnappa G. , Levy G. G.
Published: April 2015

The paper reviews the results of an experimental investigation of noise radiated from a VTOL lifting fan inlet under static inflow conditions. The results are discussed in the light of recent theoretical and experimental conclusions on compressor noise radiation, combined with relevant data on the aerodynamic characteristics of the fan. The presence of high level discrete tones, up to four harmonics of the blade passing frequency superimposed over a broadband noise extending from 200 to 15,000 cps, is attributed to close spacing between rotor and stator blades, Low levels of broadband noise were observed to be caused by low levels of turbulence at the intake. Analysis of the limited results shows the variation of broadband noise as the sixth power of the velocity of the flow relative to the blade.
Future Trends in Aircraft Engine Noise Research
Authors: Kester Jervis D.
Published: April 2015

The high bypass ratio engines being introduced into service have generally been acknowledged to provide significant improvement in noise abatement. Substanital improvements in future designs will require research into several areas of engine-component noise generation. Low-noise standards also will be influenced by the aircraft mission requirements that affect selection of the power-plant cycle. Each mission requirement presents special noise problems, which must be solved. This paper explores the relationships among aircraft mission requirements, noise research in process at Pratt & Whitney Aircraft, and trends predicted for future research.
Noise Considerations in High Bypass Ratio Fan Engine Design
Authors: Kohn A. O.
Published: April 2015

The General Electric Company is engaged in a number of programs to reduce aircraft-engine noise, ranging from the reheat turbojet for the SST to high bypass ratio lift fans for V/STOL applications. Many of these programs are government-sponsored and have been described elsewhere. The major company-sponsored program is development of the reduced-noise CF6 engine, a design undertaken to achieve a noise level significantly below that of current engines. Analysis and experimental work — done on scale model and engine fans to arrive at the best tradeoff between weight, performance, and noise — resulted in a aerodynamic design that, coupled with development of efficient acoustic treatment of the ducts, has yielded an engine measuring 10 PNdB quieter than current operational engines. The author details three specific technical problem areas (acoustic treatment, turbine noise, and modulation tones) and their impact on CF6 noise.
Some Results of Recent Research on Fan and Jet Noise
Authors: Sanders Newell D.
Published: April 2015

A 6-ft-dia low-speed fan designed for low-noise production was tested to provide data on noise generation, suppression effects of acoustic treatment, and exhaust jet noise. Preliminary results showed that the overall noise varied with the 5.5 power of the fan speed but was independent of blade loading obtained by varying back pressure at constant speed. The low-velocity jet from the fan produced noise that followed the eighth power law and was lower than predicted by extrapolation of the SAE curve. Modifying the SAE method to eliminate the effects of jet density greatly improved the agreement between prediction and data.
Results of Experiments for Determining the Influence of Blade Profile Changes and Manufacturing Tolerances on the Efficiency, the Enthalpy Drop, and the Mass Flow of Multi-Stage Axial Turbines
Authors: Bammert K. , Stobbe H.
Published: April 2015

When gas and steam turbines are in use, the blade profiles can be thinned by corrosion or erosion and thickened under the influence of deposit formation, thus causing a reduction in efficiency and lifetime. During the production of turbine blades, it is possible that the profiles often become thinner or thicker than the given specified profiles, also causing a decline in efficiency. In addition, the production costs of turbine blades are, to a considerable extent, dependent on the manufacturing tolerances. This report details the effects of thinning and thickening of the profiles on the efficiency, the drop, and the mass flow of multi-stage axial turbines.
On the Noise From Jet Diffusers
Authors: Stucky Duane L. , Marco S. M.
Published: April 2015

This investigation has shown that the addition of diffusers of various lengths with a fixed cone angle to a fixed diameter circular jet nozzle increases the noise generation when delivering the same mass flow rate. For the diffusers investigated, the far field SPL was increased with increased diffusion. Also, increased diffusion decreased the directional variation of the SPL in the far field and moved the axial position of maximum noise generation closer to the jet exit. For the longest diffuser investigated, there was considerable noise contribution from the boundary layer inside the diffuser.
Aerodynamic Development of a Radial Compressor for a 10-kw Turboalternator
Authors: Rodgers Colin
Published: April 2015

The aerodynamic development of a small high-speed radial compressor for the US Army 10-kw turboalternator is discussed, including initial performance deficiencies arising from blade contour discrepancies. Design performance requirements were attained by correcting these discrepancies and subsequently were exceeded with further geometry refinements. Aerodynamic testing included an investigation concerning the effect of shroud axial clearance on compressor performance and showed that abradable shrouds are desirable for small compressors.
Gas Turbine Engine Internal Air Systems: A Review of the Requirements and the Problems
Authors: Moore A.
Published: April 2015

This paper reviews the requirements and the problems of engine air systems design. It considers, very briefly, the overall requirements of an engine air system and also the interface of the system with the overall thermodynamic performance of an engine. It then considers aspects of air systems design which are of particular interest to the design and performance of modern high pressure engines. Problem areas such as the cooling air transfer systems, extraneous cooling air heat absorption and transient thermal analysis of engine rotor and stator assemblies are considered.
Factors Affecting Match Running Performance of Elite Soccer Players: Shedding Some Light on the Complexity
Authors: Paul Darren J. , Bradley Paul S. , Nassis George P.
Published: April 2015

Time-motion analysis is a valuable data-collection technique used to quantify the match running performance of elite soccer players. However, interpreting the reductions in running performance in the 2nd half or temporarily after the most intense period of games is highly complex, as it could be attributed to physical or mental fatigue, pacing strategies, contextual factors, or a combination of mutually inclusive factors. Given that research in this domain typically uses a reductionist approach whereby match running performance is examined in isolation without integrating other factors, this ultimately leads to a 1-dimensional insight into match performance. Subsequently, a cohesive review of influencing factors does not yet exist. The aim of this commentary is to provide a detailed insight into the complexity of match running performance and its most influential factors.
Cultivating human culture
Foragers, Farmers, and Fossil Fuels How Human Values Evolve
Ian Morris
Princeton University Press, 2015. 393 pp.
Authors: Turchin Peter
Published: April 2015

Did food and fuel help shape our value systems?
Transparency versus harassment
Authors: Halpern Michael , Mann Michael
Published: April 2015

Open records laws worldwide are critical to holding public institutions, including universities, accountable. Such laws protect against inappropriate influence on the scientific enterprise and promote public trust in the integrity of science and scientists. But the growing use of electronic communications by researchers makes these laws vulnerable to misuse. Conversations that used to occur in person and by other less-recordable means are now electronically written. Increasingly, activists across the political spectrum in several countries are requesting not only records of discussions about the strengths and weaknesses of work, but also preliminary paper drafts and private constructive criticisms from colleagues. These requests can attack and intimidate academics, threatening their reputations, chilling their speech, disrupting their research, discouraging them from tackling contentious topics, and ultimately confusing the public.
*
So what level of disclosure is appropriate? How can public accountability be balanced with the privacy essential for scientific inquiry?
Real-Time PCR Assay for Detection and Differentiation of Shiga Toxin-Producing Escherichia coli from Clinical Samples
Authors: Qin Xuan , Klein Eileen J. , Galanakis Emmanouil , Thomas Anita A. , Stapp Jennifer R. , Rich Shannon , Buccat Anne Marie , Tarr Phillip I.
Published: April 2015

Timely accurate diagnosis of Shiga toxin-producing
Escherichia coli
(STEC) infections is important. We evaluated a laboratory-developed real-time PCR (LD-PCR) assay targeting
stx
1
,
stx
2
, and

rfbE
O157

with 2,386 qualifying stool samples submitted to the microbiology laboratory of a tertiary care pediatric center between July 2011 and December 2013. Broth cultures of PCR-positive samples were tested for Shiga toxins by enzyme immunoassay (EIA) (ImmunoCard STAT! enterohemorrhagic
E. coli
[EHEC]; Meridian Bioscience) and cultured in attempts to recover both O157 and non-O157 STEC.
E. coli
O157 and non-O157 STEC were detected in 35 and 18 cases, respectively. Hemolytic uremic syndrome (HUS) occurred in 12 patients (10 infected with STEC O157, one infected with STEC O125ac, and one with PCR evidence of STEC but no resulting isolate). Among the 59 PCR-positive STEC specimens from 53 patients, only 29 (54.7%) of the associated specimens were toxin positive by EIA. LD-PCR differentiated STEC O157 from non-O157 using

rfbE
O157

, and LD-PCR results prompted successful recovery of
E. coli
O157 (
n
= 25) and non-O157 STEC (
n
= 8) isolates, although the primary cultures and toxin assays were frequently negative. A rapid “mega”-multiplex PCR (FilmArray gastrointestinal panel; BioFire Diagnostics) was used retrospectively, and results correlated with LD-PCR findings in 25 (89%) of the 28 sorbitol-MacConkey agar culture-negative STEC cases. These findings demonstrate that PCR is more sensitive than EIA and/or culture and distinguishes between O157 and non-O157 STEC in clinical samples and that
E. coli
O157:H7 remains the predominant cause of HUS in our institution. PCR is highly recommended for rapid diagnosis of pediatric STEC infections.
Global Multilocus Sequence Type Analysis of Chlamydia trachomatis Strains from 16 Countries
Authors: Herrmann Björn , Isaksson Jenny , Ryberg Martin , Tångrot Jeanette , Saleh Isam , Versteeg Bart , Gravningen Kirsten , Bruisten Sylvia
Published: April 2015

The Uppsala University
Chlamydia trachomatis
multilocus sequence type (MLST) database (
http://mlstdb.bmc.uu.se
) is based on five target regions (non-housekeeping genes) and the
ompA
gene. Each target has various numbers of alleles—
hctB
, 89; CT058, 51; CT144, 30; CT172, 38; and
pbpB
, 35—derived from 13 studies. Our aims were to perform an overall analysis of all
C. trachomatis
MLST sequence types (STs) in the database, examine STs with global spread, and evaluate the phylogenetic capability by using the five targets. A total of 415 STs were recognized from 2,089 specimens. The addition of 49
ompA
gene variants created 459 profiles. ST variation and their geographical distribution were characterized using eBURST and minimum spanning tree analyses. There were 609 samples from men having sex with men (MSM), with 4 predominating STs detected in this group, comprising 63% of MSM cases. Four other STs predominated among 1,383 heterosexual cases comprising, 31% of this group. The diversity index in ocular trachoma cases was significantly lower than in sexually transmitted chlamydia infections. Predominating STs were identified in 12 available
C. trachomatis
whole genomes which were compared to 22
C. trachomatis
full genomes without predominating STs. No specific gene in the 12 genomes with predominating STs could be linked to successful spread of certain STs. Phylogenetic analysis showed that MLST targets provide a tree similar to trees based on whole-genome analysis. The presented MLST scheme identified
C. trachomatis
strains with global spread. It provides a tool for epidemiological investigations and is useful for phylogenetic analyses.
A Novel Reporter Phage To Detect Tuberculosis and Rifampin Resistance in a High-HIV-Burden Population
Authors: O'Donnell Max R. , Pym Alexander , Jain Paras , Munsamy Vanisha , Wolf Allison , Karim Farina , Jacobs William R. , Larsen Michelle H.
Published: April 2015

Improved diagnostics and drug susceptibility testing for
Mycobacterium tuberculosis
are urgently needed. We developed a more powerful mycobacteriophage (Φ
2
GFP10) with a fluorescent reporter. Fluorescence-activated cell sorting (FACS) allows for rapid enumeration of metabolically active bacilli after phage infection. We compared the reporter phage assay to GeneXpert MTB/RIF for detection of
M. tuberculosis
and rifampin (RIF) resistance in sputum. Patients suspected to have tuberculosis were prospectively enrolled in Durban, South Africa. Sputum was incubated with Φ
2
GFP10, in the presence and absence of RIF, and bacilli were enumerated using FACS. Sensitivity and specificity were compared to those of GeneXpert MTB/RIF with an
M. tuberculosis
culture as the reference standard. A total of 158 patients were prospectively enrolled. Overall sensitivity for
M. tuberculosis
was 95.90% (95% confidence interval (CI), 90.69% to 98.64%), and specificity was 83.33% (95% CI, 67.18% to 93.59%). In acid-fast bacillus (AFB)-negative sputum, sensitivity was 88.89% (95% CI, 73.92% to 96.82%), and specificity was 83.33% (95% CI, 67.18% to 93.59%). Sensitivity for RIF-resistant
M. tuberculosis
in AFB-negative sputum was 90.00% (95% CI, 55.46% to 98.34%), and specificity was 91.94% (95% CI, 82.16% to 97.30%). Compared to GeneXpert, the reporter phage was more sensitive in AFB smear-negative sputum, but specificity was lower. The Φ
2
GFP10 reporter phage showed high sensitivity for detection of
M. tuberculosis
and RIF resistance, including in AFB-negative sputum, and has the potential to improve phenotypic testing for complex drug resistance, paucibacillary sputum, response to treatment, and detection of mixed infection in clinical specimens.
The burden of revision sinonasal surgery in the UK—data from the Chronic Rhinosinusitis Epidemiology Study (CRES): a cross-sectional study
Authors: Philpott Carl , Hopkins Claire , Erskine Sally , Kumar Nirmal , Robertson Alasdair , Farboud Amir , Ahmed Shahzada , Anari Shahram , Cathcart Russell , Khalil Hisham , Jervis Paul , Carrie Sean , Kara Naveed , Prinsley Peter , Almeyda Robert , Mansell Nicolas , Sunkaraneni Sankalp , Salam Mahmoud , Ray Jaydip , Panesaar Jaan , Hobson Jonathan , Clark Allan , Morris Steve
Published: April 2015

Objectives

The aim of this study was to investigate the surgical revision rate in patients with chronic rhinosinusitis (CRS) in the UK CRS Epidemiology Study (CRES). Previous evidence from National Sinonasal Audit showed that 1459 patients with CRS demonstrated a surgical revision rate 19.1% at 5 years, with highest rates seen in those with polyps (20.6%).

Setting

Thirty secondary care centres around the UK.

Participants

A total of 221 controls and 1249 patients with CRS were recruited to the study including those with polyps (CRSwNPs), without polyps (CRSsNPs) and with allergic fungal rhinosinusitis (AFRS).

Interventions

Self-administered questionnaire.

Primary outcome measure

The need for previous sinonasal surgery.

Results

A total of 651 patients with CRSwNPs, 553 with CRSsNPs and 45 with AFRS were included. A total of 396 (57%) patients with CRSwNPs/AFRS reported having undergone previous endoscopic nasal polypectomy (ENP), of which 182 of the 396 (46%) reported having received more than one operation. The mean number of previous surgeries per patient in the revision group was 3.3 (range 2–30) and a mean duration of time of 10 years since the last procedure. The average length of time since their first operation up to inclusion in the study was 15.5 years (range 0–74). Only 27.9% of all patients reporting a prior ENP had received concurrent endoscopic sinus surgery (ESS; n=102). For comparison, surgical rates in patients with CRSsNPs were significantly lower; 13% of cases specifically reported ESS, and of those only 30% reported multiple procedures (χ2p<0.001).

Conclusions

This study demonstrated that there is a high burden of both primary and revision surgery in patients with CRS, worst in those with AFRS and least in those with CRSsNPs. The burden of revision surgery appears unchanged in the decade since the Sinonasal Audit.
Electronic nicotine delivery devices, and their impact on health and patterns of tobacco use: a systematic review protocol
Authors: Glasser Allison M , Cobb Caroline O , Teplitskaya Lyubov , Ganz Ollie , Katz Lauren , Rose Shyanika W , Feirman Shari , Villanti Andrea C
Published: April 2015

Introduction

E-cigarettes or electronic nicotine delivery systems (ENDS) have recently attracted considerable attention. Among some individuals there is strong debate and a polarisation of views about the public health benefits versus harms of ENDS. With little regulation, the ENDS market is evolving, and new products are introduced and marketed constantly. Rapid developments in manufacturing, marketing and consumer domains related to ENDS will warrant frequent re-evaluation, based on the state of the evolving science. The purpose of this article is to describe a protocol for an ongoing comprehensive review of the published scientific literature on ENDS.

Methods and analysis

We will undertake a systematic review of published empirical research literature on ENDS using the National Library of Medicine's PubMed electronic database to search for relevant articles. Data from included studies will be extracted into a standardised form, tables with study details and key outcomes for each article will be created, and studies will be synthesised qualitatively.

Ethics and dissemination

This review synthesises published literature and presents no primary data. Therefore, no ethical approval is required for this study. Subsequent papers will provide greater detail on results, within select categories, that represent gaps in the literature base.
A geochronological framework for sedimentation and Mesoproterozoic tectono-magmatic activity in lower Belt–Purcell rocks exposed west of Kimberley, British Columbia
Authors: McFarlane Christopher R.M.
Published: April 2015

The Matthew Creek Metamorphic Zone (MCMZ) exposes what is inferred to be the lowest structural level of the lower Aldridge Formation in the Canadian portion of the Belt–Purcell Supergroup. Zircon, monazite, and titanite were dated using the U–Pb system by LA–ICP–MS. The detrital zircon populations of quartzite layers in these rocks define a provenance dominated by sources of Laurentian affinity with a minor component of non-North American ages between 1600 and 1490 Ma. Special attention was paid to monazite in sillimanite-grade metapelitic schists that was analyzed using in situ LA–ICP–MS techniques guided by BSE imaging and compositional mapping. Textural and geochronological evidence indicate that coupled dissolution–reprecipitation affected detrital monazite at 1413 ± 10 Ma. This was followed by prograde monazite growth at 1365 ± 10 Ma, synchronous with crystallization of the nearby Hellroaring Creek peraluminous granite at 1365 ± 5 Ma. Late-stage pegmatite emplacement and ductile shearing along the contact of the MCMZ and overlying rocks occurred at 1335 ± 5 Ma, interpreted as a period of post-collisional extension, core complex formation, exhumation, and decompression melting. The entire package was subsequently affected by a pervasive ∼1050 Ma hydrothermal overprint that partially reset U–Pb dates in monazite, zircon, and titanite contained in all lithologies examined. The lowermost Belt–Purcell stratigraphy in southeast British Columbia preserves a detailed record of sedimentary provenance and a long history of episodic collision and extension that must be reconciled with plate reconstruction models for the break-up of the Nuna supercontinent and assembly of Rodinia.
Snow sounds when rubbing or impacting a snow bed
Authors: Patitsas A.J.
Published: April 2015

The acoustic emissions from rubbing the ends of baseball bats, thin wood rods, and the soles of rubber boots on a snow bed were recorded and analyzed. The same analysis was also extended to the acoustic emissions from impacting a snow bed by small pestles and by subjecting a snow bed to relatively large stresses by stepping on it with shoes of variable rigidity. It is shown that when a snow bed is lightly rubbed, the acoustic emissions originate from vibration mode excitation in the rubbing body. It is argued that when highly granular cold snow is impacted by a small pestle, the acoustic emissions could originate with mode excitation in granule vibration bands around the pestle end, as in the case of impacted singing sands. Layers of highly granular and rounded snow pellets, seemingly formed from frozen raindrops, could contribute especially to snow avalanches. When walking on a snow bed, the acoustic emissions include squeaky sounds that originate from mode excitation in the shoe sole and crunchy and squeally sounds that could originate with crack growth and crystal dislocation processes in the sheared matrix of snow grains and grain bonds.
Nilpotent symmetries in supergroup field cosmology
Authors: Upadhyay Sudhaker
Published: April 2015

In this paper, we study the gauge invariance of the third quantized supergroup field cosmology which is a model for multiverse. Further, we propose both the infinitesimal (usual) as well as the finite superfield-dependent BRST symmetry transformations which leave the effective theory invariant. The effects of finite superfield-dependent BRST transformations on the path integral (so-called void functional in the case of third quantization) are implemented. Within the finite superfield-dependent BRST formulation, the finite superfield-dependent BRST transformations with specific parameter switch the void functional from one gauge to another. We establish this result for the most general gauge with the help of explicit calculations which holds for all possible sets of gauge choices at both the classical and the quantum levels.
Astrophysical aspects of milli-charged dark matter in a Higgs–Stueckelberg model
Authors: dos Santos A. L. , Hadjimichef D.
Published: April 2015

An extension of the Standard Model (SM) is studied, in which two new vector bosons are introduced, a first boson Z' coupled to the SM by the usual minimal coupling, producing an enlarged gauge sector in the SM. The second boson A' field, in the dark sector of the model, remains massless and originates a dark photon γ'. A hybrid mixing scenario is considered based on a combined Higgs and Stueckelberg mechanisms. In a Compton-like process, a photon scattered by a weakly interacting massive particles (WIMP) is converted into a dark photon. This process is studied, in an astrophysical application obtaining an estimate of the impact on stellar cooling of white dwarfs and neutron stars.
Refractive index sensing performance analysis of photonic crystal Mach–Zehnder interferometer based on BP neural network optimization
Authors: Chen Ying , Liu Teng , Wang Wenyue , Zhu Qiguang , Bi Weihong
Published: April 2015

According to the band gap and photon localization characteristics, the single-arm notching and the double-arm notching Mach–Zehnder interferometer (MZI) structures based on 2D triangular lattice air hole-typed photonic crystal waveguide are proposed. The back-propagation (BP) neural network is introduced to optimize the structural parameters of the photonic crystal MZI structure, which results in the normalized transmission peak increasing from 85.3% to 97.1%. The sensitivity performances of the two structures are compared and analyzed using the Salmonella solution samples with different concentrations in the numerical simulation. The results show that the sensitivity of the double-arm notching structure is 4583 nm/RIU, which is about 6.4 times of the single-arm notching structure, which can provide some references for the optimization of the photonic devices and the design of high-sensitivity biosensors.
Coherent population effect in a Λ-configuration atom driven by two trains of ultrashort pulses
Authors: Jin Kang , Du Yingjie
Published: April 2015

In this paper, we investigate the evolutional dynamics of a Λ-type atomic system of which two branches of transitions are driven by two trains of ultrashort pulse respectively. The accumulating of atomic populations and coherences due to excitations of successive pulses are demonstrated by the numerical simulations. The realization of the coherent population trapping (CPT) effect is verified. When the spontaneous generated coherence (SGC) is considered, the system will evolve to the dark state even when the initial state is not the dark state if the degree of the SGC is not maximal and the degree of the SGC will influence the time needed to reach the atomic steady state. With the maximal degree of SGC, whether the system will evolve into the dark state depends on the initial state. This fact means that the maximal SGC spoils the dark state geometry, which a Λ-type atom driven by light field satisfies. Additionally, we found that the involvement of the phase of the driving field can counteract the destruction stem from the maximal degree of the SGC on the dark state geometry, i.e. the system can be trapped in the dark state even when the initial state is not the dark state. Meanwhile, it is found that the phase can adjust the time needed by the system to reach the steady state in a quite wide range.
Flying-seed-like liquid crystals 5: Liquid crystals based on octakisphenylthiophthalocyanine and their optical properties
Authors: Ishikawa Aya , Ohta Kazuchika , Yasutake Mikio
Published: April 2015

We have synthesized three novel flying-seed-like liquid crystals based on phthalocyaninato copper(II) (abbreviated as PcCu ) substituted by bulky groups {(o- C1) PhS (i), (m- C1) PhS (j), [m, p-( C1)2] PhS (k)} instead of using long alkyl chains, in order to investigate their mesomorphism. Their phase transition behavior and the mesophase structures have been established by using a polarizing optical microscope, a differential scanning calorimeter, and a temperature-dependent small angle X-ray diffractometer. As the results, [(o-C1)PhS]8PcCu (8i), [(m-C1)PhS]8PcCu (8j) and {[m,p-(C1)2]PhS}8PcCu (8k) show a Coltet.omesophase at 314.9~362.9 °C, a Colro(P2m) mesophase at 287.4~334.2°C and a Colro(P2m) mesophase at 331.8~386.8°C, respectively. Very interestingly, each of the derivatives thus exhibits a columnar mesophase at very high temperatures. The mesomorphism is apparently originated from the novel bulky groups (i~k). It is also noteworthy that the Q-bands of the present PhS-containing Pc derivatives 8i~8k in THF significantly red-shift by about 35 nm in comparison with those of the corresponding PhO-containing derivatives in THF.
Geometrization of Lie and Noether symmetries and applications
Authors: Tsamparlis Michael
Published: April 2015

We derive the Lie and the Noether conditions for the equations of motion of a dynamical system in an n-dimensional Riemannian space. We solve these conditions in the sense that we express the symmetry generating vectors in terms of the collineation vectors of the space. More specifically we give two theorems which contain all the necessary conditions which allow one to determine the Lie and the Noether point symmetries of a specific dynamical system evolving in a given Riemannian space in terms of the projective and the homothetic collineations of space. We apply these theorems to various interesting situations in Newtonian Physics.
Angiotensin II receptor blockade or deletion of vascular endothelial ACE does not prevent vascular dysfunction and remodeling in 20-HETE-dependent hypertension
Authors: Garcia Victor , Joseph Gregory , Shkolnik Brian , Ding Yan , Zhang Frank Fan , Gotlinger Katherine , Falck John R. , Dakarapu Rambabu , Capdevila Jorge H. , Bernstein Kenneth E. , Schwartzman Michal Laniado
Published: April 2015

Increased vascular 20-HETE is associated with hypertension and activation of the renin-angiotensin system (RAS) through induction of vascular angiotensin-converting enzyme (ACE) expression. Cyp4a12tg mice, whose Cyp4a12-20-HETE synthase expression is under the control of a tetracycline (doxycycline, DOX) promoter, were used to assess the contribution of ACE/RAS to microvascular remodeling in 20-HETE-dependent hypertension. Treatment of Cyp4a12tg mice with DOX increased systolic blood pressure (SBP; 136 ± 2 vs. 102 ± 1 mmHg; P < 0.05), and this increase was prevented by administration of 20-HEDGE, lisinopril, or losartan. DOX-induced hypertension was associated with microvascular dysfunction and remodeling of preglomerular microvessels, which was prevented by 20-HEDGE, a 20-HETE antagonist, yet only lessened, but not prevented, by lisinopril or losartan. In ACE 3/3 mice, which lack vascular endothelial ACE, administration of 5α-dihydrotestosterone (DHT), a known inducer of 20-HETE production, increased SBP; however, the increase was about 50% of that in wild-type (WT) mice (151 ± 1 vs. 126 ± 1 mmHg). Losartan and 20-HEDGE prevented the DHT-induced increase in SBP in WT and ACE 3/3 mice. DHT treatment increased 20-HETE production and microvascular remodeling in WT and ACE 3/3 mice; however, remodeling was attenuated in the ACE 3/3 mice as opposed to WT mice (15.83 ± 1.11 vs. 22.17 ± 0.92 μm; P < 0.05). 20-HEDGE prevented microvascular remodeling in WT and ACE 3/3 mice, while losartan had no effect on microvascular remodeling in ACE 3/3. Taken together, these results suggest that RAS contributes to 20-HETE-mediated microvascular remodeling in hypertension and that 20-HETE-driven microvascular remodeling independent of blood pressure elevation does not fully rely on ACE activity in the vascular endothelium.
Long-term pathological consequences of prenatal infection: beyond brain disorders
Authors: Labouesse Marie A. , Langhans Wolfgang , Meyer Urs
Published: April 2015

Prenatal immunological adversities such as maternal infection have been widely acknowledged to contribute to an increased risk of neurodevelopmental brain disorders. In recent years, epidemiological and experimental evidence has accumulated to suggest that prenatal exposure to immune challenges can also negatively affect various physiological and metabolic functions beyond those typically associated with primary defects in CNS development. These peripheral changes include excessive accumulation of adipose tissue and increased body weight, impaired glycemic regulation and insulin resistance, altered myeloid lineage development, increased gut permeability, hyperpurinergia, and changes in microbiota composition. Experimental work in animal models further suggests that at least some of these peripheral abnormalities could directly contribute to CNS dysfunctions, so that normalization of peripheral pathologies could lead to an amelioration of behavioral deficits. Hence, seemingly unrelated central and peripheral effects of prenatal infection could represent interrelated pathological entities that emerge in response to a common developmental stressor. Targeting peripheral abnormalities may thus represent a valuable strategy to improve the wide spectrum of behavioral abnormalities that can emerge in subjects with prenatal infection histories.
5-HT2A receptor activation is necessary for CO2-induced arousal
Authors: Buchanan Gordon F. , Smith Haleigh R. , MacAskill Amanda , Richerson George B.
Published: April 2015

Hypercapnia-induced arousal from sleep is an important protective mechanism pertinent to a number of diseases. Most notably among these are the sudden infant death syndrome, obstructive sleep apnea and sudden unexpected death in epilepsy. Serotonin (5-HT) plays a significant role in hypercapnia-induced arousal. The mechanism of 5-HT's role in this protective response is unknown. Here we sought to identify the specific 5-HT receptor subtype(s) involved in this response. Wild-type mice were pretreated with antagonists against 5-HT receptor subtypes, as well as antagonists against adrenergic, cholinergic, histaminergic, dopaminergic, and orexinergic receptors before challenge with inspired CO2 or hypoxia. Antagonists of 5-HT2A receptors dose-dependently blocked CO2-induced arousal. The 5-HT2C receptor antagonist, RS-102221, and the 5-HT1A receptor agonist, 8-OH-DPAT, attenuated but did not completely block CO2-induced arousal. Blockade of non-5-HT receptors did not affect CO2-induced arousal. None of these drugs had any effect on hypoxia-induced arousal. 5-HT2 receptor agonists were given to mice in which 5-HT neurons had been genetically eliminated during embryonic life ( Lmx1b f/f/p) and which are known to lack CO2-induced arousal. Application of agonists to 5-HT2A, but not 5-HT2C, receptors, dose-dependently restored CO2-induced arousal in these mice. These data identify the 5-HT2A receptor as an important mediator of CO2-induced arousal and suggest that, while 5-HT neurons can be independently activated to drive CO2-induced arousal, in the absence of 5-HT neurons and endogenous 5-HT, 5-HT receptor activation can act in a permissive fashion to facilitate CO2-induced arousal via another as yet unidentified chemosensor system.