bluuebunny/crossref_metadata_2025 huggingface dataset:
Heuristic search for the stacking problem
Authors: Rei Rui Jorge , Pedroso João Pedro
Published: October 2011

This paper presents the Stacking Problem, a hard combinatorial optimization problem concerning handling and storage of items in a warehouse, where they are handled by a crane and organized into stacks. We define the problem, study its complexity class, and present a mathematical programming model to solve it. In order to tackle medium‐ or large‐scale instances, we propose a simulation‐based algorithm using semi‐greedy construction heuristics. This simple approach allows for multiple constructions, finding solutions within reasonable time even for large instances. Three semi‐greedy heuristics are proposed and compared in an extensive computational experiment, where we study the relation between the number of constructions and the best solution obtained using each heuristic.
Effect of Pulsatile Left Ventricular Assist System Implantation on Doppler Measurements of Renal Hemodynamics in Patients With Advanced Heart Failure
Authors: Iwashima Yoshio , Yanase Masanobu , Horio Takeshi , Seguchi Osamu , Murata Yoshihiro , Fujita Tomoyuki , Toda Kouichi , Kawano Yuhei , Nakatani Takeshi
Published: October 2011

The effects of left ventricular assist system (LVAS) implantation on renal hemodynamics remains to be fully elucidated. We evaluated renal function and intrarenal blood flow in five advanced heart failure patients who had been supported with a Toyobo LVAS for bridge to heart transplantation. Renal function expressed as estimated glomerular filtration rate (eGFR) was calculated using the modified formula of Modification of Diet in Renal Disease. Mean blood velocities in the bilateral segmental arteries during systolic and diastolic perfusion were measured using duplex Doppler sonography, and renal vascular resistance (resistive index [RI]) of the segmental arteries was defined as (peak systolic velocity [PSV]—end‐diastolic velocity [EDV])/PSV. All studies were performed before and after implantation (mean duration of support, 15.6 ± 10.9 months). LVAS implantation significantly improved eGFR (42.7 ± 7.9 to 64.1 ± 16.3 mL/min, P <  0.05). Beat‐by‐beat measurements of heart rate did not change significantly. Mean PSV decreased significantly (38.2 ± 8.9 to 28.3 ± 2.2 cm/s, P < 0.05), and mean EDV increased significantly (8.3 ± 3.2 to 11.3 ± 1.3 cm/s, P <  0.05), and thus, mean RI was significantly improved (0.79 ± 0.06 to 0.60 ± 0.04, P < 0.01). In conclusion, in advanced heart failure patients, pulsatile LVAS implantation is associated with improved renal function, and this improvement may be mediated in part through an improvement of intrarenal hemodynamics.
Influence of Bicuspid Valve Geometry on Ascending Aortic Fluid Dynamics: A Parametric Study
Authors: Vergara Christian , Viscardi Francesca , Antiga Luca , Luciani Giovanni Battista
Published: October 2011

Bicuspid aortic valve (BAV) predisposes to aortic aneurysms with a high prevalence. A first hypothesis for this phenomenon is related to fibrillin deficiency (genetic hypothesis). The present article focused on a complementary, hemodynamic hypothesis stating that it is the peculiar fluid dynamics of blood in the ascending aorta of patients with BAV configurations that leads to aneurysm formation. To corroborate this hypothesis, a parametric study was performed based on numerical simulations of ascending aorta hemodynamics with different configurations of orifice area and valve orientation. The resulting wall shear stress (WSS) distributions and degree of asymmetry of the blood jet were investigated, and surrogate indices introduced. The results showed that WSS was more pronounced in subjects with BAV morphologies, also in the nonstenotic case. In particular, a maximum WSS of 3 Pa was found (vs. 1.5 Pa in subjects with a tricuspid configuration). It is localized at the mid‐ascending aorta, the segment more prone to dilate as shown by the index related to maximum WSS (0.869 in BAV vs. 0.322 in tricuspid). Moreover, the asymmetry of the blood flow was found larger for decreasing valve area, the related index at mid‐ascending aorta being more than three times higher than that found for tricuspid configuration (0.70 vs. 0.20). Further, WSS and flow asymmetry were higher also at the sinus of Valsalva and sinotubolar junction for a latero‐lateral (LL) BAV configuration in keeping with the clinical observation on association between BAV configurations and different aortic aneurysm morphology. These findings may help explain the higher risk of aneurysm formation in BAV patients. The proposed indices will require validation prior to application in clinical settings.
The Trajectories of Adolescents’ Perceptions of School Climate, Deviant Peer Affiliation, and Behavioral Problems During the Middle School Years
Authors: Wang Ming‐Te , Dishion Thomas J.
Published: October 2011

This longitudinal study examined trajectories of change in adolescents’ perceptions of four dimensions of school climate (academic support, behavior management, teacher social support, and peer social support) and the effects of such trajectories on adolescent problem behaviors. We also tested whether school climate moderated the associations between deviant peer affiliation and adolescent problem behaviors. The 1,030 participating adolescents from eight schools were followed from sixth through eighth grades (54% female; 76% European American). Findings indicated that all the dimensions of school climate declined, and behavioral problems and deviant peer affiliation increased. Declines in each dimension were associated with increases in behavioral problems. The prediction of problem behavior from peer affiliation was moderated by adolescents’ perceptions of school climate.
The Complications of Controlling Agency Time Discretion: FDA Review Deadlines and Postmarket Drug Safety
Authors: Carpenter Daniel , Chattopadhyay Jacqueline , Moffitt Susan , Nall Clayton
Published: October 2011

Public agencies have discretion on the time domain, and politicians deploy numerous policy instruments to constrain it. Yet little is known about how administrative procedures that affect timing also affect the quality of agency decisions. We examine whether administrative deadlines shape decision timing and the observed quality of decisions. Using a unique and rich dataset of FDA drug approvals that allows us to examine decision timing and quality, we find that this administrative tool induces a piling of decisions before deadlines, and that these “just‐before‐deadline” approvals are linked with higher rates of postmarket safety problems (market withdrawals, severe safety warnings, safety alerts). Examination of data from FDA advisory committees suggests that the deadlines may impede quality by impairing late‐stage deliberation and agency risk communication. Our results both support and challenge reigning theories about administrative procedures, suggesting they embody expected control‐expertise trade‐offs, but may also create unanticipated constituency losses.
Outcome Measures for Emergency Medicine Residency Graduates: Do Measures of Academic and Clinical Performance During Residency Training Correlate With American Board of Emergency Medicine Test Performance?
Authors: Frederick Richard C. , Hafner John W. , Schaefer Timothy J. , Aldag Jean C.
Published: October 2011

ACADEMIC EMERGENCY MEDICINE 2011; 18:S59–S64 © 2011 by the Society for Academic Emergency Medicine

Objectives:  Emergency medicine (EM) residency programs are increasingly asked to have measurable outcomes of residents’ performance. Successful completion of the written and oral American Board of Emergency Medicine (ABEM) examinations is one key outcome. In the clinical practice of EM, emergency physicians (EPs) are often measured by their clinical productivity (patients per hour). This study explored the correlation between these measures of academic and clinical performance and hypothesized that clinical productivity would have a positive association with ABEM performance.

Methods:  A prospective written survey was sent to all EPs completing training at an established Midwest 3‐year EM residency program between 1994 and 2005 (53,000 annual visits in 1994 to 65,000 annual visits in 2005). Physicians self‐reported their national ABEM written and oral board scores in a blinded fashion. Simulated oral board scores and senior written in‐training examination scores were also recorded. Postgraduate Year 3 (PGY3) clinical productivity was calculated as annual patient encounters divided by hours worked. Correlations among these variables were assessed by Pearson’s correlation coefficient, with p < 0.05 being considered statistically significant. Multiple regression analysis was performed for ABEM oral and written examination scores.

Results:  Fifty‐six of 85 residents responded to the initial survey. There was no significant correlation between clinical productivity and ABEM scores, either written (r = −0.021, p = 0.881) or oral (r = −0.02, p = 0.879). There was also no significant correlation between productivity and simulated oral board scores (r = 0.065, p = 0.639) of PGY3 in‐training scores (r = 0.078, p = 0.57). As previously reported, there were positive and significant correlations between PGY3 in‐service scores and ABEM written examination scores (r = 0.60, p < 0.0001), as well as ABEM oral and written examination scores (r = 0.51, p < 0.0001). Multiple regression analysis revealed only the PGY3 in‐training examination was a significant predictor of the ABEM oral and written scores (p < 0.001).

Conclusions:  PGY3 resident clinical productivity, when measured as patients per hour, correlated poorly with academic performance when measured by written and oral ABEM scores. The PGY3 in‐training examination was predictive of the ABEM written and oral examination scores.
Maternal and neonatal outcomes following induction of labor: a cohort study
Authors: GRIVELL ROSALIE M. , REILLY AIMEE J. , OAKEY HELENA , CHAN ANNABELLE , DODD JODIE M.
Published: October 2011

Objective. To evaluate maternal and neonatal outcomes associated with birth at term by week of gestational age and also by onset of labor. Design. Cohort study. Setting. A state‐wide perinatal outcome database. Population. 28 626 women with spontaneous onset of labor, induction of labor for recognized indications and induction of labor for non‐recognized indications. Methods. Cohort study utilizing a validated dataset comparing outcomes with type of onset of labor using a log binomial model. Main outcome measures. Cesarean section, assisted vaginal birth, important measures of maternal and neonatal morbidity. Results. Induction of labor for non‐recognized indications was associated with a significantly increased risk of a range of outcomes, including cesarean section (RR 1.67, 95%CI 1.55–1.80). The lowest risk of adverse maternal and infant outcome occurred with birth between 38 and 39 weeks and with the spontaneous onset of labor. Conclusions. Induction of labor for non‐recognized indications at term is associated with an increased risk of adverse outcomes. Caution is warranted with a liberal policy of induction of labor at term in an otherwise uncomplicated pregnancy.
Social capital and self‐rated oral health among young people
Authors: Furuta Michiko , Ekuni Daisuke , Takao Soshi , Suzuki Etsuji , Morita Manabu , Kawachi Ichiro
Published: October 2011

Furuta M, Ekuni D, Takao S, Suzuki E, Morita M, Kawachi I. Social capital and self‐rated oral health among young people. Community Dent Oral Epidemiol 2012; 40: 97–104. © 2011 John Wiley & Sons A/S

Abstract –  Objectives:  A few studies have revealed the impact of neighborhood social capital on oral health among young people. We sought to examine the associations of social capital in three settings (families, neighborhoods, and schools) with self‐rated oral health among a sample of college students in Japan.

Methods:  Cross‐sectional survey of 967 students in Okayama University, aged 18 and 19 years, was carried out. Logistic regression was used to examine the associations of poor self‐rated oral health with perceptions of social capital, adjusting for self‐perceived household income category and oral health behaviors.

Results:  The prevalence of subjects with poor self‐rated oral health was 22%. Adjusted for gender, self‐perceived household income category, dental fear, toothbrush frequency, and dental floss use, poor self‐rated oral health was significantly associated with lower level of neighborhood trust [odds ratio (OR) 2.22; 95% confidence interval (CI): 1.40–3.54] and lower level of vertical trust in school (OR 1.71; 95% CI: 1.05–2.80). Low informal social control was unexpectedly associated with better oral health (OR 0.54; 95% CI: 0.34–0.85).

Conclusions:  The association of social capital with self‐rated oral health is not uniform. Higher trust is associated with better oral health, whereas higher informal control in the community is associated with worse oral health.
A case of phlegmesia cerulea dolens after dialysis catheter insertion
Authors: Mufarrij Afif Jean , Hitti Eveline
Published: October 2011

Phlegmesia cerulea dolens (PCD) is a rare complication of deep vein thrombosis characterized by massive venous thrombosis leading to arterial compromise and tissue ischaemia. PCD carries high morbidity and mortality and is an often times overlooked cause of acute limb ischaemia that must be recognized and treated promptly. Early referral for percutaneous catheter directed thrombectomy offers an alternative to thrombolysis in patients who present with venous gangrene or fail anticoagulation therapy. A case of PCD is presented in a 71‐year‐old woman with end‐stage renal disease 3 days after right femoral dialysis catheter placement.
Public Service Motivation and Political Action in College Undergraduates
Authors: TAYLOR JAMI KATHLEEN , CLERKIN RICHARD M.
Published: October 2011

This article extends the application of the public service motivation (PSM) construct from differences between volunteers and employees in the public, nonprofit, and private sectors to the phenomenon of political activities that occurs during the public policy process. Based upon regression analysis performed on a sample of undergraduate students enrolled in introductory political science courses at a large public university, PSM appears to affect overall levels of political participation. Additionally, the rational, normative, and affective dimensions of PSM appear to affect specific types of political activity in different manners. This article argues that the PSM construct provides a way to measure individual‐level receptiveness to civic motivators, an important purposive incentive that spurs political participation.

Este artículo extiende la aplicación del constructo motivacional por el servicio público a partir de diferencias entre voluntarios y empleados en el público, organizaciones sin fines de lucro y el sector privado al fenómeno de actividades políticas que ocurren durante el proceso de políticas públicas. Basado en un análisis de regresión usado en una muestra de estudiantes de licenciatura inscritos en un curso introductorio de ciencia política en una importante universidad pública, la motivación por el servicio público parece afectar todos los niveles de participación política. Adicionalmente, las dimensiones racionales, normativas y afectivas de la motivación por el servicio público parecen afectar géneros específicos de actividad política de diferentes maneras. Este estudio argumenta que el constructo motivacional por el servicio público proporciona una forma de medir niveles individuales de receptividad hacia motivadores cívicos, un importante incentivo deliberado que estimula la participación política.
Do Economic Globalization and Political Freedom Go Together?
Authors: Adolf Robert George
Published: October 2011

This is an empirical study of democratization and globalization in East and Southeast Asia and in Southern Africa (the country of Mauritius, specifically). By examining specific countries, I hoped to develop a general theory of democratization and globalization in rapidly developing countries, using a political economy approach. This approach was instrumental in discerning why some countries, notably Taiwan, were able to democratize and others, like mainland China, remain authoritarian, even in the face of rapid economic development. I compared countries at similar income levels and examined the relationship between their economic development path (globalization) and political liberalization (or lack thereof) to test the theses that globalization results in more or less political control by the government.
Effects of Ganoderma lucidum polysaccharides on IEC-6 cell proliferation, migration and morphology of differentiation benefiting intestinal epithelium healing in vitro
Authors: Sun Li-Xin , Chen Li-Hua , Lin Zhi-Bin , Qin Ying , Zhang Jia-Qi , Yang Jing , Ma Jie , Ye Ting , Li Wei-Dong
Published: October 2011

Objectives

Restoration of epithelial continuity in the intestinal surface after extensive destruction is important since intestinal epithelial cells stand as a boundary between the body's internal and external environment. Polysaccharides from Ganoderma lucidum (Gl-PS) may benefit intestinal epithelial wound healing in different aspects, which awaits clarification. To identify potential effects, a non-transformed small-intestinal epithelial cell line, IEC-6 cells, was used.

Methods

Effects on epithelial cell proliferation, migration, morphology of differentiation and transforming growth factor beta (TGF-β) protein expression, as well as the cellular ornithine decarboxylase (ODC) mRNA and c-Myc mRNA expression, were assessed, respectively, by MTT assay, wound model in vitro, observation under a microscope after hematoxylin and eosin staining, enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction assays.

Key findings

It was shown that Gl-PS stimulated IEC-6 cell proliferation and migration significantly in a dose-dependent manner; 10 µg/ml Gl-PS improved the morphology of differentiation in IEC-6 cells. Inefficacy in expression of TGF-β in IEC-6 cells indicated a possible TGF-β independent action of Gl-PS. However, Gl-PS increased ODC mRNA and c-Myc mRNA expression in a dose-dependent manner, indicating, at least partially possible involvement of ODC and c-Myc gene expression in improvement of intestinal wound healing.

Conclusions

These results suggest the potential usefulness of Gl-PS to cure intestinal disorders characterized by injury and ineffective repair of the intestinal mucosa.
An Overview of Relevant Aspects on VIM of Spar and Monocolumn Platforms
Authors: Gonçalves Rodolfo T. , Rosetti Guilherme F. , Fujarra André L. C. , Nishimoto Kazuo
Published: October 2011

Vortex-induced motions (VIM) of floating structures are very relevant for the design of mooring and riser systems. In the design phase, spar and monocolumn VIM behavior, as well as semisubmersible and tension leg platform flow-induced motions, is studied and evaluated. This paper provides a checklist of topics and evidence from a number of sources to justify the selection that should be considered when designing spars or monocolumn platforms regarding the VIM phenomenon. An overview of the influential aspects of the VIM is presented such as heading, external appendages of the hull, concomitant presence of waves and currents, motion suppressor, draft condition (immersed portion of the hull), and external damping due to the presence of risers. Previous works concerning the VIM studies on spar and monocolumn platforms are also addressed. Whenever possible, the results of experiments from diverse authors on this matter are presented and compared.
Derivation of the Angular Dispersion Error Distribution of Mirror Surfaces for Monte Carlo Ray-Tracing Applications
Authors: Cooper T. , Steinfeld A.
Published: October 2011

Of paramount importance to the optical design of solar concentrators is the accurate characterization of the specular dispersion errors of the reflecting surfaces. An alternative derivation of the distribution of the azimuthal angular dispersion error is analytically derived and shown to be equivalent to the well-known Rayleigh distribution obtained by transforming the bivariate circular Gaussian distribution into polar coordinates. The corresponding inverse cumulative distribution function applied in Monte Carlo ray-tracing simulations, which gives the dispersion angle as a function of a random number sampled from a uniform distribution on the interval (0,1), does not depend on the inverse error function, thus simplifying and expediting Monte Carlo computations. Using a Monte Carlo ray-tracing example, it is verified that the Rayleigh and bivariate circular Gaussian distribution yield the same results. In the given example, the Rayleigh method is found to be ∼40% faster than the Gaussian method.
Monte Carlo Heat Transfer Modeling of a Particle-Cloud Solar Reactor for SnO2 Thermal Reduction
Authors: Villafán-Vidales H. I. , Arancibia-Bulnes C. A. , Abanades S. , Riveros-Rosas D. , Romero-Paredes H.
Published: October 2011

A directly irradiated cavity solar reactor devoted to the thermal reduction of SnO2 particle-cloud is studied numerically by using the Monte Carlo method. The steady-state model solves the radiation and convection heat transfers in the semitransparent particle suspension and the chemical reaction. It was used to predict the temperature distribution and the reaction extent inside the cavity, as well as the theoretical thermochemical efficiency for different operational conditions. The simulations assume that the reactor contains a nonuniform size suspension of radiatively participating reacting SnO2 particles. The model takes into account the radiative characteristics of the particles, as well as the directional characteristics of the power distribution of the incoming concentrated solar energy. The particle concentration, the particle size, and the length of the reactor are varied. Results show that the particle temperature and the yield of the endothermic reaction are higher when the reactor is fed with a cloud of particles with average diameter of 20 μm. The maximal thermochemical efficiency reached is 10%, which corresponds to an optimal optical thickness of around 2.
Degradation of Mechanical Properties of Conventional and Nanophased Carbon/Epoxy Composites in Seawater
Authors: Hossain M. K. , Imran K. A. , Hosur M. V. , Jeelani S.
Published: October 2011

Composites used for marine applications are subjected to various environmental effects, such as moisture, temperature, UV radiation, and seawater. In this study, effect of seawater on the degradation of mechanical properties of conventional and nanophased carbon/epoxy composites was investigated. Epoxy resin was modified using 1 wt. %, 2 wt. %, and 3 wt. % nanoclay. Carbon/epoxy composites were fabricated by vacuum assisted resin transfer molding process and compared with neat samples with and without exposure to seawater. Nanoclay was dispersed into matrix by using magnetic stirring. Mechanical characterization performed through three point bending tests showed that 2 wt. % nanoclay loading was optimum. Flexural strength and modulus were increased by 25% and 12.51%, respectively, compared to neat system for samples not exposed to seawater. Flexure samples exposed to the seawater for 30-, 60-, and 180-day periods revealed that samples with nanoclay retained better mechanical properties compared to neat samples. After 30-day exposure to seawater, there was no significant reduction in the strength and modulus. However, flexural strength was reduced by 10.24%, 7.08%, 5.28%, and 7.13% for neat, 1 wt. %, 2 wt. %, and 3 wt. % nanoclay-infused samples, respectively, after the samples were exposed to seawater for 180-day. At the same time flexural modulus was reduced by 12.61%, 7.16%, 4.59%, and 6.11%, respectively. From scanning electron microscopy (SEM) studies, it was found that failure occurred due to delimitation and initiated from the compression side. Nanophased composites exhibited better bonding between fiber and matrix. SEM micrographs also revealed that both unconditioned and conditioned nanophased epoxy, which produce relatively rougher fracture surfaces compared to neat samples. Optical microscopy study revealed no significant physical change in outer surfaces of the samples conditioned up to a 90-day period.
Mechanical Characterization of XD-Grade Carbon Nanotube/Epon 862 Processed by Dual Phase Dispersion Technique
Authors: Okoro C. U. , Hossain M. K. , Hosur M. V. , Jeelani S.
Published: October 2011

Uniform dispersion of the constituent nanomaterial is essential in attaining optimal results for nanocomposite fabrication. In this research, a dual-phase dispersion method is studied combining a high intensity ultrasonic liquid processor with a three roll milling technique. XD-grade carbon nanotubes (XD-CNTs) were infused into Epon 862 epoxy and the mixture was then mechanically mixed with a mechanical stirrer before placing into a sonicator. This mixture was submerged continuously in a cooling bath to prevent premature polymerization. Once the sonication cycle was completed, the mixture was then placed in a three roll milling processor for six successive cycles incrementally reduced from 20 to 5 μm gap spacings at 140 rpm. Epikure curing agent W was then added to the modified resin and mixed using a high-speed mechanical stirrer. To reduce the chance of void formation, the mixture was preheated and placed in a vacuum oven to remove trapped air and reaction volatiles. Flexural and dynamic mechanical analysis (DMA) tests were performed on neat, 0.015 wt. %, and 0.15 wt. % xd-CNT/epoxy plaques to identify the loading effect on the mechanical properties of the composite material. Flexural results indicated homogeneity with improvements in mechanical properties of up to 15% in strength as well as modulus enhancement of up to 25%, respectively. Interfacial adhesion and dispersion were improved with viscosity reduction while utilizing the secondary mixing method. DMA tests resulted in an increase in storage modulus in the nanophased specimens as CNT loading increased. This is mainly attributed to enhanced CNT dispersion and distribution causing reduced polymer chain movement and increased stiffness. Scanning electron microscopy (SEM) revealed the fracture morphology of the tested specimens indicating proper dispersion of the xd-CNTs by fracture propagation and cleavage plane displacement.
Full-Scale Wind Turbine Near-Wake Measurements Using an Instrumented Uninhabited Aerial Vehicle
Authors: Kocer G. , Mansour M. , Chokani N. , Abhari R.S. , Müller M.
Published: October 2011

In this paper, the first-ever measurements of the wake of a full-scale wind turbine using an instrumented uninhabited aerial vehicle (UAV) are reported. The key enabler for this novel measurement approach is the integration of fast response aerodynamic probe technology with miniaturized hardware and software for UAVs that enable autonomous UAV operation. The measurements, made to support the development of advanced wind simulation tools, are made in the near-wake (0.5D–3D, where D is rotor diameter) region of a 2 MW wind turbine that is located in a topography of complex terrain and varied vegetation. Downwind of the wind turbine, profiles of the wind speed show that there is strong three-dimensional shear in the near-wake flow. Along the centerline of the wake, the deficit in wind speed is a consequence of wakes from the rotor, nacelle, and tower. By comparison with the profiles away from the centerline, the shadowing effects of nacelle and tower diminish downstream of 2.5D. Away from the centerline, the deficit in wind speed is approximately constant ≈ 25%. However, along the centerline, the deficit is ≈ 65% near to the rotor, 0.5D–1.75D, and only decreases to ≈ 25% downstream of 2.5D.
A Three-Equation Variant of the SST k-ω Model Sensitized to Rotation and Curvature Effects
Authors: Dhakal Tej P. , Walters D. Keith
Published: October 2011

A new variant of the SST k-ω model sensitized to system rotation and streamline curvature is presented. The new model is based on a direct simplification of the Reynolds stress model under weak equilibrium assumptions [York et al., 2009, “A Simple and Robust Linear Eddy-Viscosity Formulation for Curved and Rotating Flows,” International Journal for Numerical Methods in Heat and Fluid Flow, 19(6), pp. 745–776]. An additional transport equation for a transverse turbulent velocity scale is added to enhance stability and incorporate history effects. The added scalar transport equation introduces the physical effects of curvature and rotation on turbulence structure via a modified rotation rate vector. The modified rotation rate is based on the material rotation rate of the mean strain-rate based coordinate system proposed by Wallin and Johansson (2002, “Modeling Streamline Curvature Effects in Explicit Algebraic Reynolds Stress Turbulence Models,” International Journal of Heat and Fluid Flow, 23, pp. 721–730). The eddy viscosity is redefined based on the new turbulent velocity scale, similar to previously documented k-ɛ- υ2 model formulations (Durbin, 1991, “Near-Wall Turbulence Closure Modeling without Damping Functions,” Theoretical and Computational Fluid Dynamics, 3, pp. 1–13). The new model is calibrated based on rotating homogeneous turbulent shear flow and is assessed on a number of generic test cases involving rotation and/or curvature effects. Results are compared to both the standard SST k-ω model and a recently proposed curvature-corrected version (Smirnov and Menter, 2009, “Sensitization of the SST Turbulence Model to Rotation and Curvature by Applying the Spalart-Shur Correction Term,” ASME Journal of Turbomachinery, 131, pp. 1–8). For the test cases presented here, the new model provides reasonable engineering accuracy without compromising stability and efficiency, and with only a small increase in computational cost.
Numerical Study of Film Cooling Scheme on a Blunt-Nosed Body in Hypersonic Flow
Authors: Kim Sung In , Hassan Ibrahim
Published: October 2011

In hypersonic flight, the prediction of aerodynamic heating and the construction of a proper thermal protection system (TPS) are significantly important. In this study, the method of a film cooling technique, which is already the state of the art in cooling of gas turbine engines, is proposed for a fully reusable and active TPS. Effectiveness of the film cooling scheme to reduce convective heating rates for a blunt-nosed spacecraft flying at Mach number 6.56 and 40 deg angle of attack is investigated numerically. The inflow boundary conditions used the standard values at an altitude of 30 km. The computational domain consists of infinite rows of film cooling holes on the bottom of a blunt-nosed slab. Laminar and several turbulent calculations have been performed and compared. The influence of blowing ratios on the film cooling effectiveness is investigated. The results exhibit that the film cooling technique could be an effective method for an active cooling of blunt-nosed bodies in hypersonic flows.
Three‐dimensional anisotropic adaptive filtering of projection data for noise reduction in cone beam CT
Authors: Maier Andreas , Wigström Lars , Hofmann Hannes G. , Hornegger Joachim , Zhu Lei , Strobel Norbert , Fahrig Rebecca
Published: October 2011

Purpose:

The combination of quickly rotating C‐arm gantry with digital flat panel has enabled the acquisition of three‐dimensional data (3D) in the interventional suite. However, image quality is still somewhat limited since the hardware has not been optimized for CT imaging. Adaptive anisotropic filtering has the ability to improve image quality by reducing the noise level and therewith the radiation dose without introducing noticeable blurring. By applying the filtering prior to 3D reconstruction, noise‐induced streak artifacts are reduced as compared to processing in the image domain.

Methods:

3D anisotropic adaptive filtering was used to process an ensemble of 2D x‐ray views acquired along a circular trajectory around an object. After arranging the input data into a 3D space (2D projections + angle), the orientation of structures was estimated using a set of differently oriented filters. The resulting tensor representation of local orientation was utilized to control the anisotropic filtering. Low‐pass filtering is applied only along structures to maintain high spatial frequency components perpendicular to these. The evaluation of the proposed algorithm includes numerical simulations, phantom experiments, and in‐vivo data which were acquired using an AXIOM Artis dTA C‐arm system (Siemens AG, Healthcare Sector, Forchheim, Germany). Spatial resolution and noise levels were compared with and without adaptive filtering. A human observer study was carried out to evaluate low‐contrast detectability.

Results:

The adaptive anisotropic filtering algorithm was found to significantly improve low‐contrast detectability by reducing the noise level by half (reduction of the standard deviation in certain areas from 74 to 30 HU). Virtually no degradation of high contrast spatial resolution was observed in the modulation transfer function (MTF) analysis. Although the algorithm is computationally intensive, hardware acceleration using Nvidia's CUDA Interface provided an 8.9‐fold speed‐up of the processing (from 1336 to 150 s).

Conclusions:

Adaptive anisotropic filtering has the potential to substantially improve image quality and/or reduce the radiation dose required for obtaining 3D image data using cone beam CT.
Development of a prototype gantry system for preclinical x‐ray phase‐contrast computed tomography
Authors: Tapfer Arne , Bech Martin , Pauwels Bart , Liu Xuan , Bruyndonckx Peter , Sasov Alexander , Kenntner Johannes , Mohr Jürgen , Walter Marco , Schulz Joachim , Pfeiffer Franz
Published: October 2011

Purpose:

To explore the potential of grating‐based x‐ray phase‐contrast imaging for clinical applications, a first compact gantry system was developed. It is designed such that it can be implemented into anin‐vivo small‐animal phase‐contrast computed tomography (PC‐CT) scanner. The purpose of the present study is to assess the accuracy and quantitativeness of the described gantry in both absorption and phase‐contrast.

Methods:

A phantom, containing six chemically well‐defined liquids, was constructed. A tomography scan with cone‐beam reconstruction of this phantom was performed yielding the spatial distribution of the linear attenuation coefficient μ and decrement δ of the complex refractive index. Theoretical values of μ and δ were calculated for each liquid from tabulated data and compared with the experimentally measured values. Additionally, a color‐fused image representation is proposed to display the complementary absorption and phase‐contrast information in a single image.

Results:

Experimental and calculated data of the phantom agree well confirming the quantitativeness and accuracy of the reconstructed spatial distributions of μ and δ. The proposed color‐fused image representation, which combines the complementary absorption and phase information, considerably helps in distinguishing the individual substances.

Conclusions:

The concept of grating‐based phase‐contrast computed tomography (CT) can be implemented into a compact, cone‐beam geometry gantry setup. The authors believe that this work represents an important milestone in translating phase‐contrast x‐ray imaging from previous proof‐of‐principle experiments to first preclinical biomedical imaging applications on small‐animal models.
Degradation of Paternal Mitochondria by Fertilization-Triggered Autophagy in
C. elegans
Embryos
Authors: Sato Miyuki , Sato Ken
Published: October 2011

Maternal inheritance of mitochondrial DNA results from autophagy-dependent clearance of paternal mitochondria.
Optic disc assessment in the emergency department: a comparative study between the PanOptic and direct ophthalmoscopes
Authors: Petrushkin Harry , Barsam Allon , Mavrakakis Milt , Parfitt Andy , Jaye Peter
Published: October 2011

Optic disc assessment is an essential part of the neurological examination of acutely unwell patients. This study compares the PanOptic ophthalmoscope with the direct ophthalmoscope for accuracy of diagnosis and ease of use. Patient satisfaction was also compared for the two instruments. A single-masked prospective observational study was carried out. The authors showed that the PanOptic ophthalmoscope was more sensitive (p=0.03) and specific (p=0.03) than the direct ophthalmoscope. The PanOptic ophthalmoscope was preferred by both doctors (p=0.001) and patients (p=0.04) in terms of comfort and ease of use.
A3 Those in peril on the sea: the maritime work of the UK military SAR
Authors: Dykes L , Thomas M , Hird J
Published: October 2011

At any time, thousands of people are at sea around the UK. We wished to ascertain the nature of maritime emergencies attended by UK military (Royal Air Force/Royal Navy) SAR helicopters.

Method

All UK military SAR “medrescues” 1 January 2009–13 March 2010 were entered onto a database. Clinical scenarios were extracted from winchmen's reports. Acuity was estimated using the Manchester Triage Score.

Results

Of 907 SAR medrescues during the 15.5-month audit period, 172 (19%) were maritime.

Mean age of casualty 44 years (range 16–87); 90% male.

Of 130 reports with vessel type noted, 28% of casualties were from fishing boats, 20% military ships; 12% dive boats, 11% passenger ferries/cruise ships and 10% oil rigs. The remainder were on boats ranging from small pleasure craft to oil tankers, plus one surfer.

The aircraft was able to land on the vessel in 13% of the 168 jobs where this information was recorded, mainly oil-rigs and military ships. The remaining 87% were winched aboard the aircraft.

7% of cases were diving-related emergencies; 53% medical/surgical and 40% trauma (including drowning/near-drowning).

151/172 cases had sufficient information to enable estimation of Manchester Triage category: 66/151 (44%) were category 1 or 2 and 77/151 (51%) category 3. Only 8/151 (5%) were category 4. None were category 5.

Conclusion

Medical emergencies at sea are surprisingly diverse, with a wide variety of major and minor injuries & illnesses. This series ranges from diving emergencies, major trauma, an elderly cruise ship passenger with a ruptured AAA, and obstetric emergencies. Our data are retrospective and the MTS is not designed for prehospital use, but most maritime cases attended by RAF/RN SAR helicopters appear to be genuinely urgent. Lives would be at risk without the service, which features both winching capability & a technician or HPC-registered paramedic on board.
Morphological and swim performance variation among reproductive tactics of bluegill sunfish (Lepomis macrochirus)
Authors: Colborne S.F. , Bellemare M.C. , Peres-Neto P.R. , Neff B.D.
Published: October 2011

Ecomorphology examines the relationship between morphology and ecological characteristics often in relation to foraging, predation, and habitat use. However, ecomorphology may also be linked to reproductive behaviour (“tactic”), but few studies have examined this relationship. We examined bluegill sunfish (Lepomis macrochirus Rafinesque, 1819), a species in which some males become “parentals” while others adopt a parasitic “cuckolder” tactic. Parentals build nests, court females, and care for the young. Cuckolders instead act as “sneakers”, darting into nests while females are releasing eggs, and then transition to “satellites”, mimicking female appearance. We predicted that reproductive tactic would be associated with morphological variation and swimming performance. We collected bluegill parentals, sneakers, satellites, females, and juveniles to compare morphology, burst swim, and swim endurance. We found significant morphological variation among the groups, with only satellites and females having similar body shapes. Interestingly, satellites did not overlap in shape with sneakers, despite representing a single ontogenetic life history, providing evidence for a relationship between reproductive tactic and morphology. We also found that swim performance varied among the groups, with sneakers having the fastest burst swim and longest swim endurance. Our results indicate that reproductive tactic is an important factor in the ecomorphology of fish.
Adjusting for bias due to variability of estimated recruitments in fishery assessment models
Authors: Methot Richard D. , Taylor Ian G.
Published: October 2011

Integrated analysis models provide a tool to estimate fish abundance, recruitment, and fishing mortality from a wide variety of data. The flexibility of integrated analysis models allows them to be applied over extended time periods spanning historical decades with little information from which to estimate the annual signal of recruitment variability to modern periods in which more information about recruitment variability exists. Across this range of data availability, the estimation process must assure that the estimated log-normally distributed recruitments are mean unbiased to assure mean unbiased biomass estimates. Here we show how the estimation method implemented in the integrated analysis model, Stock Synthesis, achieves this unbiased characteristic in a penalized likelihood approach that is comparable to the results from Markov chain Monte Carlo. The total variability in recruitment is decomposed into variability among annual recruitment estimates based on information in the data and a residual variability. Because data are never perfectly informative, we show that estimated recruitment variability will always be less than the true variability among recruitments and that the method implemented here can be used to iteratively estimate the true variability among recruitments.
Water level thresholds of benthic macroinvertebrate richness, structure, and function of boreal lake stony littoral habitats
Authors: White Michael S. , Xenopoulos Marguerite A. , Metcalfe Robert A. , Somers Keith M.
Published: October 2011

We investigated the role of water level fluctuation on benthic macroinvertebrate communities of stony littoral habitats located in the Boreal Shield Ecozone. Using the reference condition approach (RCA), regression analysis, nonmetric multidimensional scaling (NMDS), and analysis of variance (ANOVA), we analyzed the benthic macroinvertebrate community structure of 20 natural lakes and 28 hydroelectric reservoirs to determine if they are structured by change in water level (amplitude). Along a gradient of amplitude intensity, we found that taxa richness decreases with increasing amplitude (r2 = 0.47–0.60). Littoral benthic macroinvertebrate community structure is significantly different in reservoirs that experience amplitudes > 2.0 m. Out of 28 reservoirs, 13 fell outside the 95.5% confidence ellipse determined by 20 reference lakes. Functional mobility group and functional feeding group composition are also altered with increasing amplitude (nonparametric ANOVA, P < 0.05). Further, a change in benthic macroinvertebrate functional composition occurs after a change in taxa richness. Interestingly, reservoirs that experienced amplitudes < 2.0 m had benthic macroinvertebrate communities whose structural and functional composition is similar to lakes experiencing natural water level fluctuations.
Chlorogenic acid differentially affects postprandial glucose and glucose-dependent insulinotropic polypeptide response in rats
Authors: Tunnicliffe Jasmine M. , Eller Lindsay K. , Reimer Raylene A. , Hittel Dustin S. , Shearer Jane
Published: October 2011

Regular coffee consumption significantly lowers the risk of type 2 diabetes (T2D). Coffee contains thousands of compounds; however, the specific component(s) responsible for this reduced risk is unknown. Chlorogenic acids (CGA) found in brewed coffee inhibit intestinal glucose uptake in vitro. The objective of this study was to elucidate the mechanisms by which CGA acts to mediate blood glucose response in vivo. Conscious, unrestrained, male Sprague–Dawley rats were chronically catheterized and gavage-fed a standardized meal (59% carbohydrate, 25% fat, 12% protein), administered with or without CGA (120 mg·kg–1), in a randomized crossover design separated by a 3-day washout period. Acetaminophen was co-administered to assess the effects of CGA on gastric emptying. The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) were measured. GLP-1 response in the presence of glucose and CGA was further examined, using the human colon cell line NCI-H716. Total area under the curve (AUC) for blood glucose was significantly attenuated in rats fed CGA (p < 0.05). Despite this, no differences in plasma insulin or nonesterified fatty acids were observed, and gastric emptying was not altered. Plasma GIP response was blunted in rats fed CGA, with a lower peak concentration and AUC up to 180 min postprandially (p < 0.05). There were no changes in GLP-1 secretion in either the in vivo or in vitro study. In conclusion, CGA treatment resulted in beneficial effects on blood glucose response, with alterations seen in GIP concentrations. Given the widespread consumption and availability of coffee, CGA may be a viable prevention tool for T2D.
Endurance and resistance training lowers C-reactive protein in young, healthy females
Authors: Daray Laura A. , Henagan Tara M. , Zanovec Michael , Earnest Conrad P. , Johnson Lisa G. , Winchester Jason , Tuuri Georgianna , Stewart Laura K.
Published: October 2011

The purpose of this study was to determine whether endurance (E) or endurance + resistance (ER) training affects C-reactive protein (CRP) and if these changes are related to alterations in fitness and (or) body composition in young females. Thirty-eight females (aged 18–24 years) were assigned to 1 of 3 groups: (1) E, (2) ER or (3) active control (AC). The E and ER groups completed 15 weeks of marathon training. The ER group performed additional resistance training and the AC group maintained their usual exercise routine. Primary outcomes were measured pre- and post-training and included anthropometric indices, dual-energy x-ray absorptiometry, plasma CRP, time to complete 1.5 miles (in minutes), and upper and lower body strength tests (i.e., 8 repetition max on bench and leg press (ER group only)). There were no differences in any variable among the groups at baseline. After training, the E group decreased time to complete 1.5 miles (p < 0.05). The AC group decreased percent and absolute body fat while the E group decreased percent body fat, absolute body fat, and android and gynoid body fat (p < 0.05). The ER group significantly improved strength (p < 0.001) and reduced plasma CRP from 2.0 ± 1.1 to 0.8 ± 0.3 mg·L–1 (p = 0.03). No significant associations were observed between CRP and measures of body composition or aerobic capacity. Combined endurance and resistance training may be an effective modality for reducing plasma CRP in young adult females independent of changes in aerobic capacity or body composition.