bluuebunny/crossref_metadata_2025 huggingface dataset:
Steady‐State Creep Analysis of Functionally Graded Rotating Cylinder
Authors: Mangal S. K. , Kapoor N. , Singh T.
Published: October 2013

Axi‐symmetric component like cylinder etc. has to operate under severe thermo‐mechanical loads, which cause significant creep. It, thus, reduces its service life. The present study investigates the steady‐state creep in a functionally graded rotating cylinder at constant angular speed. The cylinder is made up of aluminium matrix and reinforced with silicon carbide particles. The thermal gradient in the functionally graded rotating cylinder is estimated by performing finite element analysis on ANSYS software (ANSYS Inc., Canonsburg, USA). The creep behaviour of the cylinder has been described by threshold stress‐based creep law. The creep parameters are obtained by conducting regression analysis. The mathematical models have been developed to describe steady‐state creep in the cylinder. The study reveals that the radial, tangential, axial and effective stresses in the cylinder are significantly affected by the presence of particle gradient alone as well as with the presence of particle & thermal gradient both. It has been found that the creep rates have been reduced significantly by imposition of particle and thermal gradients together and thus increases the service life of cylinder.
Molecular phylogeny and revised classification of Eucosma Hübner and related genera (Lepidoptera: Tortricidae: Eucosmini)
Authors: GILLIGAN TODD M. , WRIGHT DONALD J. , MUNZ JACOB , YAKOBSON KENDRA , SIMMONS MARK P.
Published: October 2013

Eucosma Hübner is the largest genus in Tortricidae, currently comprising 298 described species. Its circumscription and those of the closely related genera Pelochrista Lederer, Phaneta Stephens and Epiblema Hübner have long been matters of confusion. Prior to the mid‐1920s, assignment to any of these genera was largely arbitrary due to a lack of clearly defined morphological limits. Here we present the first study to examine the monophyly of Eucosma and related genera using a molecular phylogenetic framework. We find that the Eucosma/Pelochrista group splits into three lineages: (i) a new genus of Pinaceae‐feeding species formerly assigned to Eucosma; (ii) a refined notion of Eucosma that is consistent with Palearctic usage and includes current North American Phaneta; and (iii) a refined concept of Pelochrista that is distinguishable from Eucosma based on female genital morphology. The new genus, described here as Eucopina Gilligan & Wright gen.n., contains the following species: Eucopina bobana (Kearfott) comb.n.; E. cocana (Kearfott) comb.n.; E. crymalana (Powell) comb.n.; E. franclemonti (Powell) comb.n.; E. gloriola (Heinrich) comb.n.; E. monitorana (Heinrich) comb.n.; E. monoensis (Powell) comb.n.; E. ponderosa (Powell) comb.n.; E. rescissoriana (Heinrich) comb.n.; E. siskiyouana (Kearfott) comb.n.; E. sonomana (Kearfott) comb.n.; E. tocullionana (Heinrich) comb.n. In addition, Ioplocama Clemens syn.n. is synonymized with Eucosma and Pygolopha Lederer syn.n. is synonymized with Pelochrista. This work is the basis for a revised world catalogue of Eucosma, Pelochrista and Phaneta in preparation.
Clinicopathological findings in non‐human primate recipients of porcine renal xenografts: quantitative and qualitative evaluation of proteinuria
Authors: Pintore Laura , Paltrinieri Saverio , Vadori Marta , Besenzon Federica , Cavicchioli Laura , De Benedictis Giulia Maria , Calabrese Fiorella , Cozzi Emanuele , Nottle Mark B. , Robson Simon C. , Cowan Peter J. , Castagnaro Massimo
Published: October 2013

Background

Immunological and histopathological features in pig‐to‐primate renal xenotransplantation are widely studied. Only limited data have been reported about clinicopathological findings in primate recipients of life‐supporting renal xenografts. In human medicine, proteinuria represents a common complication in kidney transplantation and is associated with impaired graft survival. The detection of low molecular weight proteins of tubular origin is considered an early method for predicting potential graft rejection. In this study, the presence and the significance of quantitative and qualitative proteinuria were evaluated in xenotransplanted non‐human primates in which kidney function was supported only by the transplanted organ.

Methods

Eight bilaterally nephrectomized cynomolgus monkeys (Macaca fascicularis) were transplanted with a single kidney from α1,3‐galactosyltransferase gene‐knockout (GTKO) pigs transgenic for human CD39, CD55, CD59, and α1,2‐fucosyltransferase. In addition to hematological and biochemical analyses, quantitative and qualitative analysis of proteinuria was evaluated by urinary protein‐to‐creatinine ratio (UPC ratio) and sodium dodecyl sulfate–agarose gel electrophoresis (SDS‐AGE), respectively.

Results

The main hematological and biochemical changes recorded after transplantation were a progressive anemia and a severe and progressive decrease in total proteins. In urine samples, the UPC ratio was low before transplantation and increased after transplantation. Similarly, SDS‐AGE was negative before transplantation, but bands consistent with mixed (i.e., tubular and glomerular) proteinuria were observed in all samples collected post‐transplantation.

Conclusions

The study of clinicopathological changes in cynomolgus monkey renal xenograft recipients provides a valid help in monitoring the health conditions in the post‐transplant period. Moreover, the evaluation of UPC ratio and the use of SDS‐AGE technique in urine samples of cynomolgus monkey renal xenograft recipients may be considered a valid, inexpensive, and less time‐consuming method than more sophisticated techniques in monitoring proteinuria. Proteinuria and presence of low molecular weight (LMW) proteins were consistently found in urine after transplantation, independent of fluctuations in renal function.
Energy-Consistent Force Feedback Laws for Virtual Environments
Authors: Mohtat Arash , Kövecses József
Published: October 2013

When digitally realized, virtual environments (VEs) do not perfectly match the physical environments they are supposed to emulate. This paper deals with energy aspects of such a mismatch, i.e., artificial energy leaks. A methodology is developed that employs smooth correction (SC) and leak dissipation (LD) to achieve a stable interconnection of the VE with the haptic device. The SC-LD naturally blends with the original laws for rendering the VE and gives rise to modified force feedback laws. These laws can be regarded as energy-consistent discretizations of their continuous-time counterparts. For some fundamental examples including virtual springs and masses, these laws are analytically reduced to simple closed-form equations. The methodology is then generalized to the multivariable case. Several experiments are conducted including a 2-DOF coupled nonlinear VE example, and a scenario leading to a sequence of contacts with a virtual object. Besides the conceptual advantage, simulation and experimental results demonstrate some other advantages of the SC-LD over well-known time-domain passivity methods. These advantages include improved fidelity, simpler implementation, and less susceptibility to produce impulsive/chattering response.
Dimensionless Compliance With Effective Modulus in Crack Length Evaluation for B × B Single Edge Bend Specimens
Authors: Shen Guowu , Tyson William R. , Gianetto James A. , Liang Jie
Published: October 2013

In ASTM standard E1820, the crack size, a, may be evaluated during J-integral or crack-tip opening displacement (CTOD) resistance testing using the measured crack-mouth opening displacement (CMOD) elastic unloading compliance C (UC). The equation given to relate a to dimensionless compliance BCE (the product of thickness B, the compliance C and the modulus of elasticity E) in E1820 incorporates Young's modulus E rather than the plane-strain modulus E/(1 − υ2) where υ is Poisson's ratio. However, the three-dimensional (3-D) single edge bend (SE(B)) specimens used in fracture toughness tests are in neither plane-stress nor plane-strain condition, especially for B×B SE(B) specimens which are popular in characterizing fracture toughness of pipes with surface notches. In the present study, 3-D finite element analysis (FEA) was used to evaluate the CMOD compliance of plain- and side-grooved B×B SE(B) specimens with shallow and deep cracks. Crack sizes evaluated using plane-stress and plane-strain assumptions with the CMOD compliance calculated from FEA for the 3-D specimen were compared with the actual crack size of the specimens used in FEA. It was found that the errors using plane-strain or plane-stress assumptions can be as high as 5–10%, respectively, especially for shallow-cracked specimens. In the present study, an effective modulus with value between plane-stress and plane-strain is proposed and evaluated by FEA for the 3-D B×B SE(B) specimens for use in estimating the dimensionless compliance for crack size evaluation of B×B SE(B) specimens. It is shown that the errors in crack size evaluation can be reduced to 1% and 2% for plain-sided and side-grooved specimens, respectively, using this effective modulus. The effect of material removal to accommodate integral knife edges on the CMOD compliance was studied and taken into account in the crack length evaluations in the present study. Elastic unloading tests were conducted to measure the compliance of SE(B) specimens with two widths W and notch depths a/W from 0.1 to 0.5. Notch depths of the specimens evaluated by using the measured compliance and assumptions of plane stress, plane strain, and effective moduli were compared with the notch depths of the specimens used in the tests. It was found that best agreement of notch depth was achieved using the effective modulus.
Unstably Stratified Homogeneous Turbulence as a Tool for Turbulent Mixing Modeling
Authors: Griffond J. , Gréa B. J. , Soulard O.
Published: October 2013

In this paper, we propose a kind of buoyancy-driven flow leading to unstably stratified homogeneous (USH) turbulence. This approach is developed in the context of incompressible Navier–Stokes equations under Boussinesq approximation. We show that USH turbulence is a valuable tool for understanding and modeling turbulent mixing induced by Rayleigh-Taylor (RT) instability. It is a much simpler configuration than “RT turbulence” which is in fact inhomogeneous. Thus, it gives insights in the basic mechanisms of buoyancy-driven turbulence, namely the interplay between buoyancy production, nonlinearities and dissipation. Besides, despite their differences both types of turbulence share very similar features for the large scale characteristics as well as for the inertial range spectrum structure.
Optimization of a Centrifugal Impeller for a Small Gas Turbine Engine: A Finite Element Approach
Authors: Muthu S. Esakki , Dileep S. , Mishra R. K.
Published: October 2013

Impeller is the key component in a centrifugal compressor whose rotating set of vanes gradually raise the energy of the working gas. High rotational speeds of the order of 50000 rpm that generally encountered by the impellers in small gas turbine engines need precise design optimized for safe operation within the entire envelope. In the present case the design of an impeller targeted for a pressure ratio of 3.7 is optimized using 3-D finite element model. Temperature contours and von Misses stresses are analyzed for different materials and geometrical configurations. The optimized design is finally verified for any engine order response falling within the operating speed by plotting the Campbell diagram. The factor of safety is found well within the safe limit. The structural integrity of the impeller has been validated by carrying out over-speed and burst margin tests as per military standard.
Aerodynamic Measurements on the Interaction of Secondary Jets and Separation Bubble
Authors: Samson A. , Sarkar S.
Published: October 2013

The dynamics of separation bubble under the influence of continuous jets ejected near the semi-circular leading edge of a flat plate is presented. Two different streamwise injection angles 30° and 60° and velocity ratios 0.5 and 1 for Re = 25000 and 55000 (based on the leading-edge diameter) are considered here. The flow visualizations illustrating jet and separated layer interactions have been carried out with PIV. The objective of this study is to understand the mutual interactions of separation bubble and the injected jets. It is observed that flow separates at the blending point of semi-circular arc and flat plate. The separated shear layer is laminar up to 20% of separation length after which perturbations are amplified and grows in the second-half of the bubble leading to breakdown and reattachment. Blowing has significantly affected the bubble length and thus, turbulence generation. Instantaneous flow visualizations supports the unsteadiness and development of three-dimensional motions leading to formation of Kelvin-Helmholtz rolls and shedding of large-scale vortices due to jet and bubble interactions. In turn, it has been seen that both the spanwise and streamwise dilution of injected air is highly influenced by the separation bubble.
Identification of Multiple Faults With Incomplete Response Measurements in Rotor-Bearing-Coupling Systems
Authors: Lal Mohit , Tiwari Rajiv
Published: October 2013

The turbo-generator system of the contemporary rotating machinery consists of the driver and driven shafts, which are coupled through either a rigid or flexible coupling. It needs precise and steadfast prediction of its dynamic attributes. The multiple–faults algorithm developed in [1] that identifies the bearing and coupling dynamic parameters along with residual unbalances in a rigid-rotor and flexible-bearing-coupling system. In actual practice the shaft would be flexible with MDOFs, and it would be difficult to measure all DOFs due to practical limitation of measurement locations and number of sensors. To overcome this in the present paper a dynamic condensation scheme has been applied to condense all angular DOFs (except at coupling location) and several linear DOFs (other than the bearing, disc and coupling locations). Numerical experiments have been performed to illustrate the proposed algorithm. The measurement noise has been added in numerically simulated responses and is used in the present algorithm to identify the parameters. The algorithm is found to be robust with different level of measurement noise. Modelling errors are also considered of few physical parameters and estimate shows the marginal robustness of the algorithm with the changes in the physical parameters.
Multi Eulerian PDF Transport Modelling of Turbulent Swirling Flame
Authors: Kapoor Abhinav , De Ashoke , Yadav Rakesh
Published: October 2013

The paper presents numerical investigation using Multi environmental Eulerian PDF (MEPDF) transport model for turbulence-chemistry interaction. A turbulent flame (SM1) from Sydney swirling burner database is simulated along with two isothermal cases (N29S054, N16S159) of different swirl numbers. MEPDF methodology, a probability density function (PDF) transport modeling, exploits the advantages of the PDF transport equation and is also computationally less expensive compared to popularly used Lagrangian solution approach of PDF transport equation. In the MEPDF approach, the PDF transport equation is represented by direct quadrature method of moments with presumed shape PDF and the closure of micro-mixing is achieved by interaction by exchange with mean (IEM) model. In the current work, the reacting flow results using MEPDF are reported for SM1 flame, which is a part of the database of turbulent reacting flows and widely considered as benchmark test cases for validating turbulent-chemistry interaction models. Initially, the non-reacting flows are simulated to properly choose the boundary conditions, turbulence models as well as the grid; followed by reacting flow calculations. SKE and RKE predictions show good agreement with each other while the other turbulence model exhibit substantially different behavior, especially for non-reacting case. However, RKE model exhibits substantial improvement in the case of reacting flows.
Part-Load Performance of Gas Turbines: Part I — A Novel Compressor Map Generation Approach Suitable for Adaptive Simulation
Authors: Tsoutsanis E. , Li Y. G. , Pilidis P. , Newby M.
Published: October 2013

Part-load performance prediction of gas turbines is strongly dependent on detailed understanding of engine component behavior and mainly that of compressors. The accuracy of gas turbine engine models relies on the compressor performance maps, which are obtained in costly rig tests and remain manufacturer’s proprietary information. The gas turbine research community has addressed this limitation by scaling default generic compressor maps in order to match the targeted off-design measurements. This approach is efficient in small range of operating conditions but becomes less accurate for wide range of operating conditions.

In this part of the paper a novel method of compressor map generation which has a primary objective to improve the accuracy of engine models performance at part load conditions is presented. This is to generate a generic form of equations to represent the lines of constant speed and constant efficiency of the compressor map for a generic compressor. The parameters that control the shape of the compressor map have been expressed in their simplest form in order to aid the adaptation process.

The proposed compressor map generation method has the capacity to refine current gas turbine performance adaptation techniques, and it has been integrated into Cranfield’s PYTHIA gas turbine performance simulation and diagnostics software tool.
An Effect of Spacing and Surface Finish on the Performance of Bladeless Turbine
Authors: Borate Hanumant P. , Misal Nitin D.
Published: October 2013

The Bladeless Turbine is a remarkable machine in terms of simplicity, robustness, efficiency, and applicability but little as known, even among today’s engineers, about how it works and how well it performs alongside conventional turbines. This paper presents effect of disc spacing and disc surface roughness on the performance of bladeless turbine. In this investigation, instead of blades, closely packed parallel discs are used. Resistance to fluid flow between the plates results in energy transfer to the shaft. High velocity water enters the disc pack through inlet nozzle path tangent to the outer edge of the discs. Convergent nozzle imparts high velocity water jet tangentially on disc thickness. Lower-energy water spirals toward the central exit port, adhesion, drag and impulse forces continue to convert kinetic energy to shaft rotational power. However, The Bladeless Turbine and a flexible test rig have been designed and manufactured, and experimental results are presented. An analysis of the performance and efficiency of the disc turbine is carried out. The design philosophy of the flexible test rig has been explained. Various complementary methods of measurement have been implemented and compared, and several operational experiences have been noted Experimental results for a 152mm diameter and 2mm thick discs of turbine are presented, which shows the variation of torque, output power, and efficiency as a function of angular speed. Measurements of static pressure are also taken at the inlet, Many design considerations and operational experiences are discussed. The effect of each parameter on the torque and power has been analyzed. It has been found that the spacing and surface finish has a significant effect on the power of the turbine. The maximum power obtained in this investigation was 33watts for 6discs and 0.5 mm spacing between discs with rough surface ( spiral Groove). The torque and power increases with decrease in spacing upto 0.5mm and increase in surface roughness value (Ra) 500 microns. From this investigation, it is clear that the developed bladeless turbine is working efficiently at 0.5mm spacing and 500 microns roughness disc surface.
Flow and Heat Transfer Analysis of Turbine Blade Cooling Passages Using Network Method
Authors: Alizadeh Mohammad , Izadi Ali , Fathi Alireza , Khaledi Hiwa
Published: October 2013

Modern turbine blades are cooled by air flowing through internal cooling passages. Three-Dimensional numerical simulation of these blade cooling passages is too time-consuming because of their complex geometries. These geometrical complexities exist as a result of using various kinds of cooling technologies such as rib turbulators (inline, staggered, or inclined ribs), pin fin, 90 and 180 degree turns (both sharp and gradual turns, with and without turbulators), finned passage, by-pass flow and tip cap impingement. One possible solution to simulate such sophisticated passages is to use the one-dimensional network method, which is presented in the current work. Turbine blade cooling channels are flow passages having multiple inlets and exits. The present in-house developed solver uses a network method for analyzing such a complicated flow pattern. In this method, cooling system is represented by a network of elements connected together at different nodes. Using assumed wall temperature, internal flow and heat transfer is calculated. The final goal of this computation is a set of boundary conditions for conjugate blade heat transfer simulation (coolant side boundary conditions). For validation, it is required to use experimental data that include temperature distribution of blade coolant-side walls. Since there is no experimental work with such data in the open literature, numerical computation is validated using available analytical and published numerical data. Calculated results agree well with analytical and numerical data. In order to exhibit the potential capabilities of the developed code, flow and heat transfer in a complicated internal cooling passage of a typical vane are investigated using the network method.
Effect of Thermal Conductivity on Heat Transfer From a Flat Plate With Combined Impingement and Film Cooling
Authors: Panda Rajesh Kumar , Prasad B. V. S. S. S.
Published: October 2013

The effect of solid thermal conductivity on conjugate heat transfer from a flat plate with combined impingement and film cooling is studied both experimentally and computationally. One side of the plate is exposed to hot mainstream, while the other side experiences impinging air jets. A geometric configuration with multiple staggered rows of cylindrical film holes and a matrix of impingement holes is considered. In the experiments a thermo-chromic liquid crystal (TLC) technique is used to measure the surface temperature. For the purpose of computations, the physical domain is meshed with very fine sized hexahedral and tetrahedral grids suitable for the finite volume method. Grid refinement is carried out using GCI method and SST κ-omega RANS equations are used for turbulence modeling. Three blade materials: A - with k = 0.2W/m K, B - with k = 1.5W/m K and C - with k = 15W/m K and three blowing ratios, M = 0.6, 1.0 and 1.6 are considered for the conjugate heat transfer study. A good agreement of effectiveness distribution on the interaction surface is found between the measured and the computations. On the interaction surface, heat flux values are the lowest for material A and progressively increase with increasing thermal conductivity. However the effectiveness values vary significantly for material A in the stream-wise direction. The Nusselt number on the other hand differs only slightly among different materials.
Thermodynamic Analysis of Evaporation Characteristics of Moving Two-Component Liquid Fuel Droplets in Pre-Vaporizer Systems
Authors: Raghuram S. , Raghavan Vasudevan
Published: October 2013

In the current study, a thermodynamic model is presented for predicting the vaporization characteristics of moving two-component fuel droplets, at an ambient temperature of 350 K, atmospheric pressure and with an initial droplet diameter of 100 microns, as typically observed in a gas turbine pre-vaporizing system. Liquid fuels considered are iso-octane (surrogate of gasoline) and decane (surrogate of diesel), blended with ethanol and methyl-butyrate (surrogate of biodiesel), respectively. The model evaluates the vapor-liquid equilibrium based on activity coefficients calculated using UNIFAC group contribution method. The gas-phase properties are calculated as functions of temperature and mixture molecular weight. The temporally varying parameters such as equilibrium surface temperature, concentration of the higher volatile fuel component, evaporation constant and droplet Reynolds and Nusselt numbers have been studied. Variation of integrated parameters such as time-average evaporation constant, droplet lifetime, average velocity and the final droplet penetration distance are also discussed.
Enhancement of Film Cooling Effectiveness Using Upstream Ramp
Authors: Halder Paresh , Samad Abdus
Published: October 2013

Film cooling is widely used in high-performance gas turbines to reduce surface heat flux and placing a ramp at the upstream of film cooling hole improves film cooling effectiveness. In this work, RANS based numerical simulations were carried out for a flat surface having two rows of injection holes and an upstream ramp. The parameters which were considered in this computation were different blowing ratios (M = 0.6, 1.0 and 1.6) and upstream ramp angles (α = 14° to 24°). Surface effectiveness was increased with increase in angle of upstream ramp and blowing ratio but further increasing these parameters decreased the effectiveness. The downstream of the second row hole effectiveness was more than that of the upstream hole for high blowing ratios in case of without ramp.
Experimental Investigations of an Industrial Lean Premixed Gas Turbine Combustor With High Swirling Flow
Authors: Sigfrid Ivan R. , Whiddon Ronald , Abou-Taouk Abdallah , Collin Robert , Klingmann Jens
Published: October 2013

In the interest of understanding the prospects and restrictions of fuel flexibility in a prototype industrial gas turbine combustor, an experimental study is performed. Methane is used to characterize standard gas turbine operation; in addition a non-standard fuel is explored, generic syngas (67.5 % hydrogen, 22.5 % carbon monoxide and 10 % methane). Both these gases are also investigated after dilution with Nitrogen to a Wobbe index of 15 MJ/m3. All measurements are conducted at a preheat temperature of 650 K to mimic gas turbine conditions. The pressure is atmospheric. The burner examined is a downscaled industrial 4th generation DLE (dry low emissions) burner. This swirl-stabilized burner features three concentric sectors: the RPL (rich-pilot-lean), the Pilot and the Main. The burner is designed to be coupled with a quartz combustion liner allowing a variety of laser and optical diagnostics, including PIV (Particle Image Velocimetry) and OH-pLIF (planar Laser Induced Florescence). The mentioned techniques are used herein for identification of combustion and flow phenomena. For this study the measurement region is located at the burner recirculation zone. CFD (RANS) calculations are compared with the OH-pLIF images to identify the zones of active combustion. CFD is also used to see the effect of recirculation zone position when moving towards the lean blow out limit. Additionally, integral scales are calculated for each of the combustion cases and from these, the Kolmogorov scales are estimated. The flow field, imaged by PIV, shows that the recirculation zone location along the major flow axis is strongly dependent on the presence of combustion.
Strategies for automatic online treatment plan reoptimization using clinical treatment planning system: A planning parameters study
Authors: Li Taoran , Wu Qiuwen , Zhang You , Vergalasova Irina , Lee W. Robert , Yin Fang‐Fang , Wu Q. Jackie
Published: October 2013

Purpose:

Adaptive radiation therapy for prostate cancer using online reoptimization provides an improved control of interfractional anatomy variations. However, the clinical implementation of online reoptimization is currently limited by the low efficiency of current strategies and the difficulties associated with integration into the current treatment planning system. This study investigates the strategies for performing fast (∼2 min) automatic online reoptimization with a clinical fluence‐map‐based treatment planning system; and explores the performance with different input parameters settings: dose‐volume histogram (DVH) objective settings, starting stage, and iteration number (in the context of real time planning).

Methods:

Simulated treatments of 10 patients were reoptimized daily for the first week of treatment (5 fractions) using 12 different combinations of optimization strategies. Options for objective settings included guideline‐based RTOG objectives, patient‐specific objectives based on anatomy on the planning CT, and daily‐CBCT anatomy‐based objectives adapted from planning CT objectives. Options for starting stages involved starting reoptimization with and without the original planˈs fluence map. Options for iteration numbers were 50 and 100. The adapted plans were then analyzed by statistical modeling, and compared both in terms of dosimetry and delivery efficiency.

Results:

All online reoptimized plans were finished within ∼2 min with excellent coverage and conformity to the daily target. The three input parameters, i.e., DVH objectives, starting stage, and iteration number, contributed to the outcome of optimization nearly independently. Patient‐specific objectives generally provided better OAR sparing compared to guideline‐based objectives. The benefit in high‐dose sparing from incorporating daily anatomy into objective settings was positively correlated with the relative change in OAR volumes from planning CT to daily CBCT. The use of the original plan fluence map as the starting stage reduced OAR dose at the mid‐dose region, but increased the monitor units by 17%. Differences of only 2cc or less in OAR V50%/V70Gy/V76Gy were observed between 100 and 50 iterations.

Conclusions

: It is feasible to perform automatic online reoptimization in ∼2 min using a clinical treatment planning system. Selecting optimal sets of input parameters is the key to achieving high quality reoptimized plans, and should be based on the individual patientˈs daily anatomy, delivery efficiency, and time allowed for plan adaptation.
Inversion of seabed attenuation using time-warping of close range data
Authors: Zeng Juan , Chapman N. Ross , Bonnel Julien
Published: October 2013

An inversion scheme based on time-warping is presented for estimating seabed sound attenuation from modal dispersion of close-range single-hydrophone data. The dispersion information is extracted directly from the warped signal spectrum. Seabed sound speed and density are inverted from the modal group velocity curves, and the attenuation is inverted from the normalized modal amplitudes. The method is applied to experimental data collected in the Yellow Sea of China during the winter of 2002. The inverted sound speed and density are consistent with the sand-silt-clay sediment at the site, and the attenuation is nonlinear over the frequency band from 125–500 Hz.
Parasexuality and Ploidy Change in Candida tropicalis
Authors: Seervai Riyad N. H. , Jones Stephen K. , Hirakawa Matthew P. , Porman Allison M. , Bennett Richard J.
Published: October 2013

Candida
species exhibit a variety of ploidy states and modes of sexual reproduction. Most species possess the requisite genes for sexual reproduction, recombination, and meiosis, yet only a few have been reported to undergo a complete sexual cycle including mating and sporulation.
Candida albicans
, the most studied
Candida
species and a prevalent human fungal pathogen, completes its sexual cycle via a parasexual process of concerted chromosome loss rather than a conventional meiosis. In this study, we examine ploidy changes in
Candida tropicalis
, a closely related species to
C. albicans
that was recently revealed to undergo sexual mating.
C. tropicalis
diploid cells mate to form tetraploid cells, and we show that these can be induced to undergo chromosome loss to regenerate diploid forms by growth on sorbose medium. The diploid products are themselves mating competent, thereby establishing a parasexual cycle in this species for the first time. Extended incubation (>120 generations) of
C. tropicalis
tetraploid cells under rich culture conditions also resulted in instability of the tetraploid form and a gradual reduction in ploidy back to the diploid state. The fitness levels of
C. tropicalis
diploid and tetraploid cells were compared, and diploid cells exhibited increased fitness relative to tetraploid cells
in vitro
, despite diploid and tetraploid cells having similar doubling times. Collectively, these experiments demonstrate distinct pathways by which a parasexual cycle can occur in
C. tropicalis
and indicate that nonmeiotic mechanisms drive ploidy changes in this prevalent human pathogen.
Effects of Electroacupuncture on Stress-Related Symptoms in Medical Students: A Randomised Placebo-Controlled Study
Authors: Dias Marcio , Vellarde Guillermo Coca , Olej Beni , Teófilo Salgado Ana Emília , de Barros Rezende Ighor
Published: October 2013

Objective

To assess the effects of electroacupuncture (EA) on relieving stress-related symptoms—sleep disorders, anxiety, depression and burnout—in medical students.

Methods

Eighty-two students were randomised into an EA treatment group (n=30), a sham TENS group (n=18) and an untreated control group (n=34). EA was applied at a continuous frequency of 2 Hz to the limbs, face, ears and scalp for 20 min once a week, over 6–8 weeks. Sham transcutaneous electrical nerve stimulation (TENS) was performed on similar sites for the same number of times in each session and for the same length of time. Outcome measurements included a comparison of the indices obtained by different self-applied questionnaires before and after treatment. The surveys used were the Mini-Sleep Questionnaire (MSQ), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), the Beck Depression and Anxiety Inventories (BDI and BAI) and the Maslach Burnout Inventory—Student Survey (MBI-SS), in addition to the Quality of Life Questionnaire—abbreviated version (WHOQOL-bref).

Results

EA significantly improved scores on the MSQ, PSQI, BDI and the cynicism and academic efficacy (AE) dimensions of the MBI-SS in relation to the control. Sleep quality (MSQ) improved from 36.9 (SD 7.6) to 25.0 (5.7) with EA, 37.6 (6.0) to 32.1 (6.9) with sham TENS, and 36.5 (5.9) to 33.6 (6.7) in the controls (p=0.0000). Compared with the sham TENS group, EA significantly reduced scores on the PSQI. Score improvements in the sham TENS group in relation to control group were significant in the MSQ, BDI and AE. In the EA group, the number of students with better scores after intervention was significantly higher for the MSQ, PSQI, ESS and BAI. This only occurred for the MSQ in the sham TENS group and for the MSQ and ESS in the control group.

Conclusions

EA significantly reduced stress-related mental symptoms. The improvement obtained by sham TENS compared with the control group confirmed the presence of a placebo effect resulting from the treatment ritual.
Validity of AHRQ patient safety indicators derived from ICD-10 hospital discharge abstract data (chart review study)
Authors: Quan Hude , Eastwood Cathy , Cunningham Ceara Tess , Liu Mingfu , Flemons Ward , De Coster Carolyn , Ghali William A ,   for the IMECCHI investigators
Published: October 2013

Objective

To assess if the Agency for Healthcare Research and Quality  patient safety indictors (PSIs) could be used for case findings in the International Classification of Disease 10th revision (ICD-10) hospital discharge abstract data.

Design

We identified and randomly selected 490 patients with a foreign body left during a procedure (PSI 5—foreign body), selected infections (IV site) due to medical care (PSI 7—infection), postoperative pulmonary embolism (PE) or deep vein thrombosis (DVT; PSI 12—PE/DVT), postoperative sepsis (PSI 13—sepsis)and accidental puncture or laceration (PSI 15—laceration) among patients discharged from three adult acute care hospitals in Calgary, Canada in 2007 and 2008. Their charts were reviewed for determining the presence of PSIs and used as the reference standard, positive predictive value (PPV) statistics were calculated to determine the proportion of positives in the administrative data representing ‘true positives’.

Results

The PPV for PSI 5—foreign body was 62.5% (95% CI 35.4% to 84.8%), PSI 7—infection was 79.1% (67.4% to 88.1%), PSI 12—PE/DVT was 89.5% (66.9% to 98.7%), PSI 13—sepsis was 12.5% (1.6% to 38.4%) and PSI 15—laceration was 86.4% (75.0% to 94.0%) after excluding those who presented to the hospital with the condition.

Conclusions

Several PSIs had high PPV in the ICD administrative data and are thus powerful tools for true positive case finding. The tools could be used to identify potential cases from the large volume of admissions for verification through chart reviews. In contrast, their sensitivity has not been well characterised and users of PSIs should be cautious if using them for ‘quality of care reporting’ presenting the rate of PSIs because under-coded data would generate falsely low PSI rates.
Development of leaf shape in two North American native species ofAmpelopsis(Vitaceae)
Authors: Jones A.W. , Doughan B.G. , Gerrath J.M. , Kang J.
Published: October 2013

The Vitaceae (grape family) is a large group of plants with a world-wide distribution. Despite the economic importance of cultivated grapes (Vitis vinifera L.), very little is known about leaf development in the Vitaceae. The genus Ampelopsis contains simple- and compound-leafed forms making it an appropriate genus in which to conduct a comparative developmental study. The Ampelopsis clade diverged early from the rest of the Vitaceae, and the simple- and compound-leaf morphologies are separated into two distinct lineages, leaving the question of how this morphological disjunct arose and what the ancestral leaf shape of this genus might have been. Thus, understanding the development of this trait will clarify our understanding of basic Vitaceae leaf characters and of leaf shape evolution. We found that although the primordia of both the simple- and compound-leafed species shared a fundamental plan that would be predicted to result in a mature complex leaf shape at the outset, their developmental trajectory diverges early in development. We also identified key morphological landmarks that suggest homology between the two species. Based on current phylogenetic analysis, we discuss how our developmental study likely points to homologies that reflect their recent common ancestry despite the morphological disjunct observed in the genus.
Staging ecology of Semipalmated Plover (Charadrius semipalmatus) and Semipalmated Sandpiper (Calidris pusilla) juveniles in the St. Lawrence River Estuary during fall migration
Authors: Turcotte Yves , Lamarre Jean-François , Bêty Joël
Published: October 2013

The acquisition of body reserves by migrating shorebirds at specific staging sites is critical for reaching their breeding or wintering grounds. As many North American shorebird populations are declining, major staging sites need to be identified for effective conservation plans. Changes in body mass of Semipalmated Plover (Charadrius semipalmatus Bonaparte, 1825) and Semipalmated Sandpiper (Calidris pusilla (L., 1766)) juveniles, as well as length of stay and daily movements by Semipalmated Plover juveniles during fall migration, were studied in the St. Lawrence River Estuary in southern Quebec, Canada. Most juveniles of both species captured early in the migration period weighed less than the estimated mean fat-free mass. Body mass increased steadily in juveniles of both species during staging. Mean body masses of birds captured in our study area were similar to or higher than those of juveniles of both species captured along the North Atlantic coast. Length of stay of radio-tracked Semipalmated Plover juveniles ranged from 2 to 28 days. Body mass at capture and length of stay were negatively associated, suggesting that individuals refuelled before resuming their migration. Overall, these results provide evidence that the St. Lawrence River Estuary is an important staging site for Semipalmated Plover and Semipalmated Sandpiper juveniles.
GENERATION OF MULTI-WING CHAOTIC ATTRACTORS FROM A LORENZ-LIKE SYSTEM
Authors: LAI QIANG , GUAN ZHI-HONG , WU YONGHONG , LIU FENG , ZHANG DING-XUE
Published: October 2013

In this paper, two methods are proposed to construct multi-wing chaotic attractors based on a Lorenz-like autonomous chaotic system. The first is switching method which can directly multiply the wings of the system without segment linearization of the system. The second is coordinate transition method which is related to the initial value of the system. Moreover, theoretical analysis and simulation results show the effectiveness of these two methods.
TURING PATTERN FORMATION IN A TWO-SPECIES NEGATIVE FEEDBACK SYSTEM WITH CROSS-DIFFUSION
Authors: YANG XIYAN , YUAN ZHANJIANG , ZHOU TIANSHOU
Published: October 2013

Pattern formation is a ubiquitous phenomenon in the natural world. Previous studies showed that for an activator–inhibitor system without cross-diffusion, spatial patterns can be formed only when the diffusion of the inhibitor is significantly faster than that of the activator. However, cross-diffusion exists extensively in real systems, especially in biological systems. Here, we study a prototypic two-species negative feedback system with cross-diffusion. By performing stability analysis of equilibrium state, we find sufficient conditions for Turing instability. Both analytical and numerical results demonstrate that mutual diffusions of the two species can lead to the Turing pattern formation regardless of differences in self-diffusion coefficients. However, in the absence of the mutual diffusion or even if there is the cross-diffusion of only one species, the system cannot exhibit Turing patterns. Our results reveal the mechanism of Turing pattern formation in a class of reaction–diffusion systems, where mutual diffusion between species plays a key role.
The criticality of metals: a perspective for geologists
Authors: Graedel T. E. , Nassar N. T.
Published: October 2013

The criticality of metals (the quality, state, or degree of being of the highest importance) is of increasing concern as populations and wealth increase and as mineral extraction follows. Many characteristics are involved in determining criticality, and those involving geology are among the most important. We discuss the state of knowledge of mineable resources across the periodic table, and how those determinations factor into criticality evaluations. We then illustrate criticality evaluations of the copper ore group elements for the specific example of the UK. Given the importance of the ore metals over the long term, we argue that efforts on the part of the geological community to update and maintain criticality-related information deserve much more attention than they are now receiving.
Assisted Gene Flow to Facilitate Local Adaptation to Climate Change
Authors: Aitken Sally N. , Whitlock Michael C.
Published: October 2013

Assisted gene flow (AGF) between populations has the potential to mitigate maladaptation due to climate change. However, AGF may cause outbreeding depression (especially if source and recipient populations have been long isolated) and may disrupt local adaptation to nonclimatic factors. Selection should eliminate extrinsic outbreeding depression due to adaptive differences in large populations, and simulations suggest that, within a few generations, evolution should resolve mild intrinsic outbreeding depression due to epistasis. To weigh the risks of AGF against those of maladaptation due to climate change, we need to know the species' extent of local adaptation to climate and other environmental factors, as well as its pattern of gene flow. AGF should be a powerful tool for managing foundation and resource-producing species with large populations and broad ranges that show signs of historical adaptation to local climatic conditions.
Cytonuclear Genomic Interactions and Hybrid Breakdown
Authors: Burton Ronald S. , Pereira Ricardo J. , Barreto Felipe S.
Published: October 2013

Reduced fitness in interpopulation hybrids can be a first indication of genetic incompatibilities that may ultimately lead to reproductive isolation and speciation. A growing number of cases of hybrid breakdown have been traced to incompatibilities between the nuclear genome and the organellar genomes of the mitochondria and chloroplasts. Although these organellar genomes derive from ancient bacterial endosymbioses, they have been vastly reduced in size and now encode relatively few genes. The remaining genes are necessary but not sufficient for organelle function. In fact, most proteins functioning in the organelles are encoded in the nuclear genome and need to be imported after synthesis in the cytosol. The necessary interactions between organelle and nuclear genomes have resulted in some degree of coadaptation within all natural populations. Hybridization brings together previously untested allelic combinations and can disrupt intergenomic coadaptation, resulting in organelle dysfunction and, consequently, hybrid breakdown.
Ecological and Evolutionary Misadventures ofSpartina
Authors: Strong Donald R. , Ayres Debra R.
Published: October 2013

Spartina species of the mid-low intertidal areas are powerful ecological engineers that are highly valued where they are native. Elsewhere, they overgrow native salt marsh and open intertidal mudflats, diminish biota, increase costs of managing wildlife, and interfere with human uses of estuaries. Huge efforts have been mounted to kill some populations of invading Spartina. All large Spartina invasions are by S. densiflora (2n = 7x = 70) or S. alterniflora (2n = 6x = 62) or hybrids between the hexaploid species (2n = 6x). Hybridization is a recurrent theme in Spartina; the allododecaploid S. anglica (2n = 12x = 120) and the hybrid swarm in San Francisco Bay arose through the introductions of S. alterniflora into the range of native Spartina species. The ancient hybrid S. densiflora also hybridized with native Spartina species. Hybridization promotes the evolution of highly invasive populations and hampers control efforts. Whether Spartina, native and not, would protect the shore as sea levels rise depends upon unimpeded areas for upward marsh growth and sufficient sediment, conditions that are often not satisfied.
How Was the Australian Flora Assembled Over the Last 65 Million Years? A Molecular Phylogenetic Perspective
Authors: Crisp Michael D. , Cook Lyn G.
Published: October 2013

Australia has a mostly dry, open, fire-shaped landscape of sclerophyllous and xeromorphic flora dominated by eucalypt and acacia trees, with diverse shrubs from a few families such as Myrtaceae, Proteaceae, and Fabaceae. Using molecular phylogenies to test hypotheses derived from the fossil record, we review the principal forces that transformed the ancestral Gondwanan rainforest through the Cenozoic. Today's vegetation is a mix of ancient radiations that have persisted in Australia through dramatic climate change since before the breakup of Gondwana, and more recent lineages whose ancestors arrived by trans-oceanic dispersal. Signatures in the fossil record of lineage turnover and trait evolutionary change are detected in phylogenies, but often at earlier dates. The Australian biota is a sample of the wider region, with extinction of some taxa and radiation of others (due to chance and opportunity), but biotic and abiotic interactions have resulted in a unique flora and fauna.