bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Criterion to Estimate Performance of Pulse Jet Mixed Vessels
Authors: Pease Leonard F. , Bamberger Judith Ann , Mahoney Lenna A. , Yokuda S. Thomas , Minette Michael J.
Published: December 2016

Pulse jet mixed process vessels comprise a key element of the U.S. Department of Energy’s strategy to process millions of gallons of legacy nuclear waste slurries. Slurry suctioned into a pulse jet mixer (PJM) tube at the end of one pulse is pneumatically driven from the PJM toward the bottom of the vessel at the beginning of the next pulse, forming a jet. The jet front traverses the distance from nozzle outlet to the bottom of the vessel and spreads out radially. Varying numbers of PJMs are typically arranged in a ring configuration within the vessel at a selected radius and operated concurrently. Centrally directed radial flows from neighboring jets collide to create a central upwell that elevates the solids in the center of the vessel when the PJM tubes expel their contents.

An essential goal of PJM operation is to elevate solids to the liquid surface to minimize stratification. Solids stratification may adversely affect throughput of the waste processing plant. Unacceptably high slurry densities at the base of the vessel may plug the pipeline through which the slurry exits the vessel. Additionally, chemical reactions required for processing may not achieve complete conversion. To avoid these conditions, a means of predicting the elevation to which the solids rise in the central upwell that can be used during vessel design remains essential.

In this paper we present a simple criterion to evaluate the extent of solids elevation achieved by a turbulent upwell jet. The criterion asserts that at any location in the central upwell the local velocity must be in excess of a cutoff velocity to remain turbulent. We find that local velocities in excess of 0.6 m/s are necessary for turbulent jet flow through both Newtonian and yield stress slurries. By coupling this criterion with the free jet velocity equation relating the local velocity to elevation in the central upwell, we estimate the elevation at which turbulence fails, and consequently the elevation at which the upwell fails to further lift the slurry. Comparing this elevation to the vessel fill level predicts whether the jet flow will achieve the full vertical extent of the vessel at the center.

This simple local-velocity criterion determines a minimum PJM nozzle velocity at which the full vertical extent of the central upwell in PJM vessels will be turbulent. The criterion determines a minimum because flow in regions peripheral to the central upwelling jet may not be turbulent, even when the center of the vessel in the upwell is turbulent, if the jet pulse duration is too short. The local-velocity criterion ensures only that there is sufficient wherewithal for the turbulent jet flow to drive solids to the surface in the center of the vessel in the central upwell.
Effect of Kinematic Viscosity of Barrier Fluids on the Performance of a Bi-Directional Integrated Pumping Ring for Dual Mechanical Seals
Authors: Warda H. A. , Adam I. G. , Rashad A. B. , Gamal Aldin M. W.
Published: December 2016

An experimental investigation is carried out to evaluate the performance of bi-directional pumping ring for dual mechanical seals. An experimental setup is constructed, and appropriate instrumentation are employed to measure the pressure, temperature, and flow rate of the barrier fluid. The experimental study focused on the influence of the kinematic viscosity of the barrier fluid on the performance of the pumping ring. This is done by monitoring Q-ΔP curves for various barrier fluids and temperature ranges. The tests are conducted for industrial barrier fluid compositions which are recommended by vendors of dual mechanical seals, such as Propylene Glycol-water mixtures and Diesel fuel (Grade D2).

Despite the importance of the measured performance curves for process control purposes, indicated experimental curved are generalized so that they can be employed in prediction of pumping ring performance for different sizes and operational conditions. Moreover, they can be utilized for numerical models validation.
Characterization of Vortex Dynamics in the Near Wake of an Oscillating Flexible Foil
Authors: Siala Firas F. , Totpal Alexander D. , Liburdy James A.
Published: December 2016

An experimental study was conducted to explore the effect of surface flexibility at the leading and trailing edges on the near-wake flow dynamics of a sinusoidal heaving foil. Mid-span particle image velocimetry measurements were taken in a closed loop wind tunnel at a Reynolds number of 25,000 and at a range of reduced frequencies (k = fc/U) from 0.09–0.20. Time resolved and phase locked measurements were used to describe the mean flow characteristics and phase averaged vortex structures and their evolution throughout the oscillation cycle. Large eddy scale decomposition and swirl strength analysis were used to quantify the effect of flexibility on the vortical structures. The results demonstrate that flexibility at the trailing edge has a minimal influence on the mean flow characteristics when compared to the purely rigid foil. The mean velocity deficit for the flexible trailing edge and rigid foils is shown to remain constant for all reduced frequencies tested. However, the trailing edge flexibility increases the swirl strength of the small scale structures, which results in enhanced cross stream dispersion of the mean velocity profile. Flexibility at the leading edge is shown to generate a large scale leading edge vortex for k ≥ 0.18. This results in a reduction in the swirl strength due to the complex vortex interactions when compared to the flexible trailing edge and rigid foils. Furthermore, it is shown that the large scale leading edge vortex is responsible for extracting a significant portion of the energy from the mean flow, resulting in a substantial reduction of mean flow momentum in the wake. The kinetic energy loss in the wake is shown to scale well with the energy content of the leading edge vortex.
Time- and Phase-Averaged Boundary Layer Measurements on a Controlled NACA 0025 Airfoil
Authors: Feero Mark A. , Lavoie Philippe , Sullivan Pierre E.
Published: December 2016

The ability of active flow control through synthetic jet actuator to reattach the stalled flow on a NACA 0025 at low Reynolds number was investigated experimentally. Wind tunnel tests were performed where boundary layer velocity profiles were measured by hot-wire anemometry. The effects of excitation frequency and momentum input, quantified by the blowing ratio were the focus of the measurements. Using both low- and high-frequency actuation, the boundary layer was reattached in a time-averaged sense, however the mechanism of control was not the same. Low-frequency excitation lead to oscillations in the boundary layer at the control frequency due to the passage of a vortex transporting high-momentum to the inner boundary layer. Conversely, high-frequency control caused a steady reattachment of the boundary layer.
Accelerating the High-Fidelity Simulation of Turbulence: Ensemble Averaging
Authors: Makarashvili Vakhtang , Merzari Elia , Obabko Aleksandr , Fischer Paul , Siegel Andrew
Published: December 2016

Computational fluid dynamics (CFD) is increasingly used to simulate complex industrial systems. Most CFD analysis relies on the Reynolds-averaged Navier-Stokes (RANS) approach and traditional two-equation turbulence models. Higher-fidelity approaches to the simulation of turbulence such as wall-resolved large eddy simulation (LES) and direct numerical simulation (DNS) remain limited to smaller applications or to large supercomputing platforms. Nonetheless, continued advances in supercomputing are enabling the simulation of physical systems of increasing size and complexity. These simulations can be used to gain unprecedented insight into the physics of turbulence in complex flows and will become more widespread as petascale architectures become more accessible.

As the scale and size of LES and DNS simulations increase, however, the limitations of current algorithms become apparent. For larger systems, more temporal and spatial scale must be resolved, thus increasing the time-scale separation. While the smaller time scales dictate the size and the computational cost associated with each time step, the larger time scales dictate the length of the transient. An increased time-scale separation leads to smaller time steps and longer transients, eventually leading to simulations that are impractical or infeasible. In practice the presence of multiple and strongly separated time scales limits the effectiveness of CFD algorithms for LES and DNS applied to large industrial systems. Moreover, the situation is likely to become worse as even larger systems are simulated, thus increasing the size and length of transients. At the same time transients currently simulated on petascale architectures are unlikely to become any faster on exascale architectures.

This paper presents an ensemble-averaging technique for transient simulations, aimed at collecting averaged turbulent statistics faster. The focus is on ergodic flows and simulations. Ensemble averaging involves creating multiple models and combining them to produce a desired output. This technique is commonplace in machine learning and artificial neural networks, and it is at the basis of RANS/URANS turbulence modeling. In the proposed approach, multiple instances of the same ergodic flows are simulated in parallel for a short time and summed to create an ensemble. Provided each instance is sufficiently statistically decorrelated, this allows considerable reduction in the time to solution.

This paper focuses on the theory and implementation of the methodology in Nek5000, a massively parallel open-source spectral-element code. Also presented is the application of the method to the DNS and LES simulation of channel flow and pipe flow.
Further Developments in Numerical Simulations of Wind Turbine Flows Using the Actuator Line Method
Authors: O’Dea Murphy Leo , Guessous Laila
Published: December 2016

Current large-scale wind turbine installations are sited using layouts based on site topology, real estate costs and restrictions, and turbine power output. Existing optimization programs attempt to site multiple turbines based on simple geometric turbine wake models, which typically overestimate individual turbine output. In addition, advanced Computational Fluid Dynamics (CFD) modeling of individual turbine wake fields have revealed complex flow patterns and “wake meandering” which have not been taken into account in current optimization and flow field models. CFD models of entire turbine fields have had limited application because of the enormous compute resources required; limitations of the simplified turbine models used which do not provide high resolution results in the wake field; and the lack of efforts to adapt the results of complex CFD output to analytical models which can be incorporated into wind turbine siting optimization routines.

In this paper, we report on our efforts to simulate flow past wind turbines using a new adaptation of the Actuator Line (AL) method for turbine blade modeling. This method creates a geometric representation of each rotating turbine blade. Grid points in the CFD flow field are selected within the outline of the blades and near downstream planes, and the aerodynamic forces are calculated using traditional blade element equations. The forces are distributed using an automated routine which dynamically determines the application area based on the number of applied grid points at each time step. Turbine blades are rotated in time with progressing CFD field calculations. This method distributes blade forces without using a geometric distribution function used in other recent research. Blade forces are then input as body forces into the Navier Stokes equations in the host CFD program. A Smagorisnky LES turbulence model is employed to model turbulent effects.

To improve accuracy and reduce computing power requirements, the advanced parallel CFD code, NEK5000, is used in this study. FORTRAN subroutines are written to generate the actuator line and blade geometry, and to calculate the blade lift and drag forces. These subroutines are then linked to the solver source code and compiled.

Details of the actuator line setup and calculations, LES turbulence model, CFD flow simulation setup, and results from current turbine runs will be presented. Current results are consistent with published research. A roadmap to ongoing development will also be discussed.
Energy Harvesting From Vortical Flows by a Passive Heaving Foil
Authors: Wei Z. , Zheng Z. Charlie
Published: December 2016

This paper studies energy harvesting of a two-dimensional foil in the wake downstream of a cylinder. The airfoil is passively mobile in the transverse direction. An immersed-boundary method with a fluid-structure interaction model is validated and employed to carry out the numerical simulation. For improving the numerical stability, a modified low-storage 3rd-order Runge-Kutta scheme is implemented for time integration. The performance of this temporal scheme on reducing spurious pressure oscillations of the immersed-boundary method is demonstrated. The simulation shows a foil emerged in a vortical wake achieves better energy harvesting performance than that in a uniform flow. The types of dynamic response for the energy harvester are identified and the properties of vortical wakes are found to be of pivotal importance in obtaining the desired periodic response of the foil.
CFD Simulation of Round Impinging Jet and Comparison With Experimental Data
Authors: Arabnejad H. , Mansouri A. , Shirazi S. A. , McLaury B. S.
Published: December 2016

In this work, fluid dynamics of a turbulent round impinging jet has been studied using Computational Fluid Dynamics (CFD) and the results have been compared with experimental data from the literature. The fluid was water with density of 1000 kg/m3 and the average velocity of the submerged jet was kept constant at 10.7 m/s while the liquid viscosity varied from 1 cP to 100 cP. Different turbulence models including k-ε, k-ω and Reynolds Stress Model (RSM) have been employed in ANSYS FLUENT and the predicted axial and radial velocity profiles at various distances from the wall are compared with LDV data. It was observed that at locations away from the target wall, predicted velocities are comparable to the measured velocities for all the viscosities. However, near the wall, the deviation between the CFD predictions and experimental measurements become noticeable. The performance of k-ω model and RSM are found to be better than the k-ε model especially for the highest viscous fluid, but no model was found to be superior for all conditions and at all locations.
Utility of transthoracic echocardiography (TTE) in assessing fluid responsiveness in critically ill patients – a challenge for the bedside sonographer.
Authors: Mielnicki Wojciech , Dyla Agnieszka , Zawada Tomasz
Published: December 2016

Transthoracic echocardiography (TTE) has become one of the most important diagnostic tools in the treatment of critically ill patients. It allows clinicians to recognise potentially reversible life-threatening situations and is also very effective in the monitoring of the fluid status of patients, slowly substituting invasive methods in the intensive care unit. Hemodynamic assessment is based on a few static and dynamic parameters. Dynamic parameters change during the respiratory cycle in mechanical ventilation and the level of this change directly corresponds to fluid responsiveness. Most of the parameters cannot be used in spontaneously breathing patients. For these patients the most important test is passive leg raising, which is a good substitute for fluid bolus. Although TTE is very useful in the critical care setting, we should not forget the important limitations, not only technical ones but also caused by the critical illness itself. Unfortunately, this method does not allow continuous monitoring and every change in the patient’s condition requires repeated examination.Keywords: hypovolaemia; non-invasive monitoring; intensive care unit; transthoracic echocardiography
Schwannoma of the median nerve mimicking carpal tunnel syndrome in a pregnant patient. Case report.
Authors: Giasna Giokits-Kakavouli , Micu Mihaela C. , Micu Romeo
Published: December 2016

In patients with symptoms of a peripheral neuropathy especially during pregnancy, use of imaging techniques such as Ultrasound (US) and Magnetic Resonance Imaging (MRI) may be essential for the diagnostic accomplishment. A 30-weekspregnant diabetic female attending US evaluation due to intermittent hand pain, numbness, and weakness bilaterally. Although, the US evaluation revealed the median nerve (MN) normal size, echogenicity and echo-texture within the right carpal tunnel; the US assessment applied proximally to the carpal tunnel, revealed a hypoechoic tumor-like mass and increased MN cross section area. In transverse view, the MN was detected as an eccentric, hypoechoic structure compressed by the aforementioned mass. A presence of MN schwannoma or neurofibroma was suspected. US has been proved to be extremely useful to determine location, extent as well as the type of nerve lesion.
ACOUSTICAL NEWS–USA
Authors: Holland Christy K.
Published: December 2016

Abstract not available.
Comparison of Critical Power and W′ Derived From 2 or 3 Maximal Tests
Authors: Simpson Len Parker , Kordi Mehdi
Published: December 2016

Purpose:

Typically, accessing the asymptote (critical power; CP) and curvature constant (W′) parameters of the hyperbolic power–duration relationship requires multiple constant-power exhaustive-exercise trials spread over several visits. However, more recently single-visit protocols and personal power meters have been used. This study investigated the practicality of using a 2-trial, single-visit protocol in providing reliable CP and W′ estimates.

Methods:

Eight trained cyclists underwent 3- and 12-min maximal-exercise trials in a single session to derive (2-trial) CP and W′ estimates. On a separate occasion a 5-min trial was performed, providing a 3rd trial to calculate (3-trial) CP and W′.

Results:

There were no differences in CP (283 ± 66 vs 282 ± 65 W) or W′ (18.72 ± 6.21 vs 18.27 ± 6.29 kJ) obtained from either the 2-trial or 3-trial method, respectively. After 2 familiarization sessions (completing a 3- and a 12-min trial on both occasions), both CP and W′ remained reliable over additional separate measurements.

Conclusions:

The current study demonstrates that after 2 familiarization sessions, reliable CP and W′ parameters can be obtained from trained cyclists using only 2 maximal-exercise trials. These results offer practitioners a practical, time-efficient solution for incorporating power–duration testing into applied athlete support.
Gait Asymmetry During 400- to 1000-m High-Intensity Track Running in Relation to Injury History
Authors: Gilgen-Ammann Rahel , Taube Wolfgang , Wyss Thomas
Published: December 2016

Purpose:

To quantify gait asymmetry in well-trained runners with and without previous injuries during interval training sessions incorporating different distances.

Methods:

Twelve well-trained runners participated in 8 high-intensity interval-training sessions on a synthetic track over a 4-wk period. The training consisted of 10 × 400, 8 × 600, 7 × 800, and 6 × 1000-m running. Using an inertial measurement unit, the ground-contact time (GCT) of every step was recorded. To determine gait asymmetry, the GCTs between the left and right foot were compared.

Results:

Overall, gait asymmetry was 3.3% ± 1.4%, and over the course of a training session, the gait asymmetry did not change (F1,33 = 1.673, P = .205). The gait asymmetry of the athletes with a previous history of injury was significantly greater than that of the athletes without a previous injury. However, this injury-related enlarged asymmetry was detectable only at short (400 m), but not at longer, distances (600–1000 m).

Conclusion:

The gait asymmetry of well-trained athletes differed, depending on their history of injury and the running distance. To detect gait asymmetries, high-intensity runs over relatively short distances are recommended.
Relationships Between Internal and External Match-Load Indicators in Soccer Match Officials
Authors: Castillo Daniel , Weston Matthew , McLaren Shaun J. , Cámara Jesús , Yanci Javier
Published: December 2016

The aims of this study were to describe the internal and external match loads (ML) of refereeing activity during official soccer matches and to investigate the relationship among the methods of ML quantification across a competitive season. A further aim was to examine the usefulness of differential perceived exertion (dRPE) as a tool for monitoring internal ML in soccer referees. Twenty field referees (FRs) and 43 assistant referees (ARs) participated in the study. Data were collected from 30 competitive matches (FR = 20 observations, AR = 43 observations) and included measures of internal (Edwards’ heart-rate-derived training impulse [TRIMPEDW]) ML, external (total distance covered, distance covered at high speeds, and player load) ML, and ML differentiated ratings of perceived respiratory (sRPEres) and leg-muscle (sRPEmus) exertion. Internal and external ML were all greater for FRs than for ARs (–19.7 to –72.5), with differences ranging from very likely very large to most likely extremely large. The relationships between internal-ML and external-ML indicators were, in most cases, unclear for FR (r < .35) and small to moderate for AR (r < .40). The authors found substantial differences between RPEres and RPEmus scores in both FRs (0.6 AU; ±90% confidence limits 0.4 AU) and ARs (0.4; ±0.3). These data demonstrate the multifaceted demands of soccer refereeing and thereby highlight the importance of monitoring both internal and external ML. Moreover, dRPE represents distinct dimensions of effort and may be useful in monitoring soccer referees’ ML during official matches.
How Does a Short, Interrupted Recovery Break Affect Performance and How Is It Assessed? A Study on Acute Effects
Authors: Pelka Maximilian , Ferrauti Alexander , Meyer Tim , Pfeiffer Mark , Kellmann Michael
Published: December 2016

A recovery process with optimal prerequisites that is interrupted is termed disrupted recovery. Whether this process has an influence on performance-related factors needs to be investigated. Therefore, the aim of this study was to examine how a short disturbance of a recovery phase is assessed and whether subsequent repeated-sprint performance is affected by it. A quasi-experimental 2 × 2-factor crossover design with 34 sport-science undergraduate students (age 20.3 ± 2.1 y) was applied. Factors were the type of intervention (power nap vs systematic breathing; between-subjects) and the experimental condition (disturbed vs nondisturbed break; within-subject). Repeated-sprint performance was measured through 6 × 4-s sprint protocols (with 20-s breaks) before and after a 25-min recovery break on 2 test days. Subjective evaluation of the interventions was measured through the Short Recovery and Stress Scale and a manipulation check assessing whether participants experienced the recovery phase as efficacious and pleasant. Regarding the objective data, no significant difference between sprint performances in terms of average peak velocity (m/s) on the treadmill was found. The manipulation check revealed that disturbed conditions were rated significantly lower than regular conditions in terms of appreciation, t31 = 3.09, P = .01. Short disturbances of recovery do not seem to affect subsequent performance; nevertheless, participants assessed disturbed conditions more negatively than regular conditions. In essence, the findings indicate a negligible role of short interruptions on an objective level. Subjectively, they affected the performance-related assessment of the participants and should be treated with caution.
Telomere Length in Elite Athletes
Authors: Muniesa Carlos A. , Verde Zoraida , Diaz-Ureña Germán , Santiago Catalina , Gutiérrez Fernando , Díaz Enrique , Gómez-Gallego Félix , Pareja-Galeano Helios , Soares-Miranda Luisa , Lucia Alejandro
Published: December 2016

Growing evidence suggests that regular moderate-intensity physical activity is associated with an attenuation of leukocyte telomere length (LTL) shortening. However, more controversy exists regarding higher exercise loads such as those imposed by elite-sport participation.

Methods:

The authors investigated LTL differences between young elite athletes (n = 61, 54% men, age [mean ± SD] 27.2 ± 4.9 y) and healthy nonsmoker, physically inactive controls (n = 64, 52% men, 28.9 ± 6.3 y) using analysis of variance (ANOVA).

Results:

Elite athletes had, on average, higher LTL than control subjects, 0.89 ± 0.26 vs 0.78 ± 0.31, P = .013 for the group effect, with no significant sex (P = .995) or age effect (P = .114).

Conclusions:

The results suggest that young elite athletes have longer telomeres than their inactive peers. Further research might assess the LTL of elite athletes of varying ages compared with both age-matched active and inactive individuals.
Vertical Jump Biomechanics Altered With Virtual Overhead Goal
Authors: Ford Kevin R. , Nguyen Anh-Dung , Hegedus Eric J. , Taylor Jeffrey B.
Published: December 2016

Virtual environments with real-time feedback can simulate extrinsic goals that mimic real life conditions. The purpose was to compare jump performance and biomechanics with a physical overhead goal (POG) and with a virtual overhead goal (VOG). Fourteen female subjects participated (age: 18.8 ± 1.1 years, height: 163.2 ± 8.1 cm, weight 63.0 ± 7.9 kg). Sagittal plane trunk, hip, and knee biomechanics were calculated during the landing and take-off phases of drop vertical jump with different goal conditions. Repeated-measures ANOVAs determined differences between goal conditions. Vertical jump height displacement was not different during VOG compared with POG. Greater hip extensor moment (P < .001*) and hip angular impulse (P < .004*) were found during VOG compared with POG. Subjects landed more erect with less magnitude of trunk flexion (P = .002*) during POG compared with VOG. A virtual target can optimize jump height and promote increased hip moments and trunk flexion. This may be a useful alternative to physical targets to improve performance during certain biomechanical testing, screening, and training conditions.
Whole-Body Vibration Training Improves Heart Rate Variability and Body Fat Percentage in Obese Hispanic Postmenopausal Women
Authors: Severino Gregory , Sanchez-Gonzalez Marcos , Walters-Edwards Michelle , Nordvall Michael , Chernykh Oksana , Adames Jason , Wong Alexei
Published: December 2016

The present study examined the effects of a 6-week whole-body vibration training (WBVT) regimen on heart rate variability (HRV) and body composition in obese Hispanic postmenopausal women. Participants were randomly assigned to either WBVT (n = 13) or a nonexercising control group (n = 14). HRV and body composition were measured before and after 6 weeks. There was a significant group by time interaction (P < .05) for heart rate, sympathovagal balance, and body fat percentage (BF%) such that all significantly decreased (P < .05); and R-R intervals significantly increased (P < .05) following WBVT compared to no changes after control. The changes in sympathovagal balance were correlated with changes in BF% (r = .63, P < .05). Our findings indicate that WBVT improves HRV and BF% in obese Hispanic postmenopausal women. The improvement in BF% partially explained the decrease in sympathovagal balance. Since obese and older individuals are at increased risk of developing cardiovascular diseases, they could potentially benefit from WBVT.
Influence of Habitual Physical Activity During Late Pregnancy on the Duration of Labor
Authors: Kondo Yuki , Sawa Ryuichi , Ebina Aoi , Takada Masayo , Fujii Hiromi , Okuyama Yoko , Tanikawa Yuko , Souke Kaoru , Ono Rei
Published: December 2016

Background:

Physical activity during pregnancy has numerous benefits, but the influence on the duration of labor is unclear. We investigated the influence of habitual physical activity during late pregnancy on the duration of labor, with consideration of previous delivery experience and the stage of labor.

Methods:

This prospective study included 103 women (48 nulliparous, 55 multiparous) in late pregnancy. Habitual physical activity was evaluated using the Baecke physical activity questionnaire (BQ). Women were divided into a high activity group (HA) and a low activity group (LA) based on their median total BQ score. Data pertaining to the duration of labor were obtained from the birth records after delivery.

Results:

In multiparous women, the duration of the second stage of labor was significantly shorter in the HA group than in the LA group [median (range): HA, 11 min (1–102 min); LA, 20 min (4–175 min); P < .05]. The significant difference persisted after adjusting for confounding variables (standardized β = –0.34; P = .01). In nulliparous women, there were no significant differences in duration of labor between groups.

Conclusions:

Higher physical activity in multiparous women during late pregnancy might positively influence the duration of the second stage of labor.
Physical Education Policies and Practices in California Private Secondary Schools
Authors: Kahan David , McKenzie Thomas L.
Published: December 2016

Background:

Physical education (PE) is mandated in most states, but few studies of PE in private schools exist.

Methods:

We assessed selected PE policies and practices in private secondary schools (grades 6 to 12) in California using a 15-item questionnaire related to school characteristics and their PE programs.

Results:

Responding schools (n = 450; response rate, 33.8%) were from 37 counties. Most were coeducational (91.3%) and had a religious affiliation (83%). Secular schools had more PE lessons, weekly PE min, and smaller class sizes. Most schools met guidelines for class size, but few met national recommendations for weekly PE minutes (13.7%), not permitting substitutions for PE (35.6%), and programs being taught entirely by PE specialists (29.3%).

Conclusions:

Private schools, which serve about 5 million US children and adolescents, may be falling short in providing quality PE. School stakeholders should encourage adoption and implementation of policies and practices that abide by professional guidelines and state statutes.
Receptor dimer stabilization by hierarchical plasma membrane microcompartments regulates cytokine signaling
Authors: You Changjiang , Marquez-Lago Tatiana T. , Richter Christian Paolo , Wilmes Stephan , Moraga Ignacio , Garcia K. Christopher , Leier André , Piehler Jacob
Published: December 2016

Single-molecule tracking and spatial stochastic modeling reveal receptor dimer stabilization by nanoscale confinement zones.
Polymerization of a divalent/tetravalent metal-storing atom-mimicking dendrimer
Authors: Albrecht Ken , Hirabayashi Yuki , Otake Masaya , Mendori Shin , Tobari Yuta , Azuma Yasuo , Majima Yutaka , Yamamoto Kimihisa
Published: December 2016

The phenylazomethine dendrimer exhibits “atom mimicry,” and its polymerization (and Lewis acid accumulation) is demonstrated.
Multiple Evolutionary Trajectories Have Led to the Emergence of Races in Fusarium oxysporum f. sp. lycopersici
Authors: Biju V. Chellappan , Fokkens Like , Houterman Petra M. , Rep Martijn , Cornelissen Ben J. C.
Published: December 2016

Race 1 isolates of
Fusarium oxysporum
f. sp.
lycopersici
(FOL) are characterized by the presence of
AVR1
in their genomes. The product of this gene, Avr1, triggers resistance in tomato cultivars carrying resistance gene
I
. In FOL race 2 and race 3 isolates,
AVR1
is absent, and hence they are virulent on tomato cultivars carrying
I
. In this study, we analyzed an approximately 100-kb genomic fragment containing the
AVR1
locus of FOL race 1 isolate 004 (FOL004) and compared it to the sequenced genome of FOL race 2 isolate 4287 (FOL4287). A genomic fragment of 31 kb containing
AVR1
was found to be missing in FOL4287. Further analysis suggests that race 2 evolved from race 1 by deletion of this 31-kb fragment due to a recombination event between two transposable elements bordering the fragment. A worldwide collection of 71 FOL isolates representing races 1, 2, and 3, all known vegetative compatibility groups (VCGs), and five continents was subjected to PCR analysis of the
AVR1
locus, including the two bordering transposable elements. Based on phylogenetic analysis using the EF1-α gene, five evolutionary lineages for FOL that correlate well with VCGs were identified. More importantly, we show that FOL races evolved in a stepwise manner within each VCG by the loss of function of avirulence genes in a number of alternative ways.

IMPORTANCE
Plant-pathogenic microorganisms frequently mutate to overcome disease resistance genes that have been introduced in crops. For the fungus
Fusarium oxysporum
f. sp.
lycopersici
, the causal agent of
Fusarium
wilt in tomato, we have identified the nature of the mutations that have led to the overcoming of the
I
and
I-2
resistance genes in all five known clonal lineages, which include a newly discovered lineage. Five different deletion events, at least several of which are caused by recombination between transposable elements, have led to loss of
AVR1
and overcoming of
I
. Two new events affecting
AVR2
that led to overcoming of
I-2
have been identified. We propose a reconstruction of the evolution of races in FOL, in which the same mutations in
AVR2
and
AVR3
have occurred in different lineages and the FOL pathogenicity chromosome has been transferred to new lineages several times.
Cell wall mechanical properties as measured with bacterial thread made from Bacillus subtilis
Authors: Mendelson N H , Thwaites J J
Published: December 2016

Engineering approaches used in the study of textile fibers have been applied to the measurement of mechanical properties of bacterial cell walls by using the Bacillus subtilis bacterial thread system. Improved methods have been developed for the production of thread and for measuring its mechanical properties. The best specimens of thread produced from cultures of strain FJ7 grown in TB medium at 20 degrees C varied in diameter by a factor of 1.09 over a 30-mm thread length. The stress-strain behavior of cell walls was determined over the range of relative humidities between 11 and 98%. Measurements of over 125 specimens indicated that cell wall behaved like other viscoelastic polymers, both natural and man-made, exhibiting relaxation under constant elongation and recovery upon load removal. This kinetic behavior and also the cell wall strength depended greatly on humidity. The recovery from extension observed after loading even up to a substantial fraction of the breaking load indicated that the properties measured were those of cell wall material rather than of behavior of the thread assemblage. Control experiments showed that neither drying of thread nor the length of time it remained dry before testing influenced the mechanical properties of the cell walls. Specimens drawn from TB medium and then washed in water and redrawn were found to be stiffer and stronger than controls not washed. However, tensile properties were not changed by exposure of cells to lysozyme before thread production. This suggests that glycan backbones are not arranged along the length of the cell cylinder. The strength of the cell wall in vivo was estimated by extrapolation to 100% relative humidity to be about 3 N/mm2. Walls of this strength would be able to bear a turgor pressure of 6 atm (ca. 607.8 kPa), but if the increase in strength of water-washed threads was appropriate, the figure could be 24 atm (ca. 2,431.2 kPa).
DNA sequence, products, and transcriptional pattern of the genes involved in production of the DNA replication inhibitor microcin B17
Authors: Genilloud O , Moreno F , Kolter R
Published: December 2016

The 3.8-kilobase segment of plasmid DNA that contains the genes required for production of the DNA replication inhibitor microcin B17 was sequenced. The sequence contains four open reading frames which were shown to be translated in vivo by the construction of fusions to lacZ. The location of these open reading frames fits well with the location of the four microcin B17 production genes, mcbABCD, identified previously through genetic complementation. The products of the four genes have been identified, and the observed molecular weights of the proteins agree with those predicted from the nucleotide sequence. The transcription of these genes was studied by using fusions to lacZ and physical mapping of mRNA start sites. Three promoters were identified in this region. The major promoter for all the genes is a growth phase-regulated OmpR-dependent promoter located upstream of mcbA. A second promoter is located within mcbC and is responsible for a low-level basal expression of mcbD. A third promoter, located within mcbD, promotes transcription in the reverse direction starting within mcbD and extending through mcbC. The resulting mRNA appears to be an untranslated antisense transcript that could play a regulatory role in the expression of these genes.
Immunological characterization of Rhizobium leguminosarum outer membrane antigens by use of polyclonal and monoclonal antibodies
Authors: de Maagd R , de Rijk R , Mulders I H , Lugtenberg B J
Published: December 2016

Surface antigens of Rhizobium leguminosarum biovar viciae strain 248 were characterized by using polyclonal and monoclonal antibodies. With Western immunoblotting as the criterion, an antiserum raised against living whole cells recognized mainly flagellar antigens and the O-antigen-containing part of the lipopolysaccharide (LPS). Immunization of mice with a peptidoglycan-outer membrane complex yielded eight monoclonal antibodies, of which three reacted with LPS and five reacted with various sets of outer membrane protein antigens. The observation that individual monoclonal antibodies react with sets of related proteins is discussed. Studies of the influence of calcium deficiency and LPS alterations on surface antigenicity showed that in normally grown wild-type cells, the O-antigenic side chain of LPS blocks binding of an antibody to a deeper-lying antigen. This antigen is accessible to antibodies in cells grown under calcium limitation as well as in O-antigen-lacking mutant cells. Two of the antigen groups which can be distinguished in cell envelopes of free-living bacteria were depleted in cell envelopes of isolated bacteroids, indicating that the monoclonal antibodies could be useful tools for studying the differentiation process from free-living bacteria to bacteroids.
Localization and symbiotic function of a region on the Rhizobium leguminosarum Sym plasmid pRL1JI responsible for a secreted, flavonoid-inducible 50-kilodalton protein
Authors: de Maagd R A , Spaink H P , Pees E , Mulders I H , Wijfjes A , Wijffelman C A , Okker R J , Lugtenberg B J
Published: December 2016

A previously described (R. A. de Maagd, C. A. Wijffelman, E. Pees, and B. J. J. Lugtenberg, J. Bacteriol. 170:4424-4427, 1988) Sym plasmid-dependent, naringenin-inducible 50-kilodalton protein of Rhizobium leguminosarum biovar viciae is further characterized in this paper. The protein was overproduced by constructing a strain containing multiple copies of the R. meliloti nodD gene, which facilitated its purification. An antiserum was used to screen Tn5 insertion mutants located in the pRL1JI region found to be responsible for the production of the 50-kilodalton protein. These inserts define a new nod locus left of the nod genes identified previously. Mutations in this region affect the nodulation ability in a way which is dependent on the bacterial background as well as on the host plant. The mutants nodulate normally in a strain RBL1532 (R. leguminosarum biovar viciae strain 248, cured of its Sym plasmid) background on all three tested host plant species. In contrast, in a strain RBL5045 (R. leguminosarum biovar trifolii strain RCR5, cured of its Sym plasmid) background, nodulation on Vicia sativa is severely impaired, whereas nodulation on Vicia hirsuta and Trifolium subterraneum is apparently unaltered.
Purification and properties of glutamine synthetase from the non-N2-fixing cyanobacterium Phormidium laminosum
Authors: Blanco F , Alańa A , Llama M J , Serra J L
Published: December 2016

Soluble glutamine synthetase activity (L-glutamate:ammonia ligase, ADP forming, EC 6.3.1.2) was purified to electrophoretic homogeneity from the filamentous non-N2-fixing cyanobacterium Phormidium laminosum (OH-1-p.Cl1) by using conventional purification procedures in the absence of stabilizing ligands. The pure enzyme showed a specific activity of 152 mumol of gamma-glutamylhydroxamate formed.min-1 (transferase activity), which corresponded to 4.4 mumol of Pi released.min-1 (biosynthetic activity). The relative molecular mass of the native enzyme was 602 kilodaltons and was composed of 12 identically sized subunits of 52 kilodaltons. Biosynthetic activity required the presence of Mg2+ as an essential activator, although Co2+ and Zn2+ were partially effective. The kinetics of activation by Mg2+, Co2+, and Zn2+ were sigmoidal, and concentrations required for half-maximal activity were 18 mM (h = 2.2), 6.3 mM (h = 5.6), and 6.3 mM (h = 2.45), respectively. However, transferase activity required Mn2+ (Ka = 3.5 microM), Cu2+, Co2+, or Mg2+ being less effective. The substrate affinities calculated for L-Glu, ammonium, ATP, L-Gln, and hydroxylamine were 15, 0.4, 1.9 (h = 0.75), 14, and 4.1 mM, respectively. Optimal pH and temperature were 7.2 and 55 degrees C for biosynthetic activity and 7.5 and 45 degrees C for transferase activity. The biosynthetic reaction mechanism proceeded according to an ordered three-reactant system, the binding order being ammonium, L-Glu, and ATP. The presence of Mn2+ or Mg2+ drastically affected the thermostability of transferase and biosynthetic activities. Heat inactivation of biosynthetic activity in the presence of Mn2+ obeyed first-order kinetics, with an Ea of 76.8 kcal (ca. 321 kJ) mol-1. Gly, L-Asp, L-Ala, L-Ser and, with lower efficiency, L-Lys and L-Met, L-Lys, and L-Glu inhibited only transferase activity. No cumulative inhibition was observed when mixtures of amino acids were used. Biosynthetic activity was inhibited by AMP (Ki= 7 mM), ADP (Ki= 2.3 mM), p-hydroxymercuribenzoate (Ki= 25 microM), and L-methionine-D, L-sulfoximine (Ki= 2 microM). The enzyme was not activated in vitro by chemically reduced Anabaena thioredoxin. This is the first report of glutamine synthetase activity purified from a filamentous non-N2-fixing cyanobacterium.
Wide distribution of homologs of Escherichia coli Kdp K+-ATPase among gram-negative bacteria
Authors: Walderhaug M O , Litwack E D , Epstein W
Published: December 2016

We used Southern blotting to screen a variety of bacterial genes for homology to the kdp genes of Escherichia coli, genes that encode an ATP-driven K+ transport system. We found that most enterobacteria have sequences homologous to those of the three kdp structural genes and the kdpD regulatory gene. A number of distantly related species, including some cyanobacteria, have sequences homologous to those of the structural genes but not the regulatory gene. In all cases only a single region of homology was found. These results suggest that ATP-driven transport systems similar to the Kdp system in structure and regulation are found in many enteric organisms. In other gram-negative organisms, the ATPase is more divergent, retaining good homology at the DNA level only to the highly conserved phosphorylated subunit of the ATPase.
Regulation of luminescence by cyclic AMP in cya-like and crp-like mutants of Vibrio fischeri
Authors: Dunlap P V
Published: December 2016

Mutants of Vibrio fischeri MJ-1 (wild type) apparently deficient in adenylate cyclase (cya-like) or cyclic AMP receptor protein (crp-like) were isolated and characterized. Compared with MJ-1, the mutants produced low levels of luminescence and luciferase. Addition of cyclic AMP restored wild-type levels of luminescence and luciferase in the cya-like mutant but not in the crp-like mutant. The results are consistent with the hypothesis that in V. fischeri cyclic AMP and cyclic AMP receptor protein are required for induction of the luminescence system.
Spermidine synthesis by Pseudomonas sp. strain Kim, previously reported to lack this polyamine
Authors: Rosano C L , Braun C B , Hurwitz C
Published: December 2016

Pseudomonas sp. strain Kim has previously been reported to be the only known naturally occurring organism lacking spermidine. We now show that it synthesizes this polyamine. The apparent lack of intracellular levels of spermidine results from an efficient conversion of spermidine to putrescine and hydroxyputrescine.
rhs gene family of Escherichia coli K-12
Authors: Sadosky A B , Davidson A , Lin R J , Hill C W
Published: December 2016

Two additional members of a novel Escherichia coli gene family, the rhs genes, have been cloned and characterized. The structures of these loci, rhsC and rhsD, have been compared with those of rhsA and rhsB. All four loci contain a homologous 3.7-kilobase-pair core. Sequence comparison of the first 300 nucleotides of the cores showed that rhsA, rhsB, and rhsC are closely related, with only 1 to 2% sequence divergence, whereas rhsD is 18% divergent from the others. The beginning of the core coincides with the initiation of an open reading frame that extends beyond the 300 nucleotides compared. Whether a protein product is produced from this open reading frame has not been established. However, nucleotide substitutions which differentiate the cores have highly conservative effects on the predicted protein products; this suggests that products are made from the open reading frame and are under severe selection. The four rhs loci have been placed on both the genetic and restriction maps of E. coli K-12. A fifth rhs locus remains to be characterized. In terms of size, number, and sequence conservation, the rhs genes make up one of the most significant repetitions in E. coli, comparable to the rRNA operons.
SecA protein autogenously represses its own translation during normal protein secretion in Escherichia coli
Authors: Schmidt M G , Oliver D B
Published: December 2016

The Escherichia coli secA gene, whose expression is responsive to the protein secretion status of the cell, is the second gene in an operon. We found that both the basal and induced levels of SecA biosynthesis are dependent on prior translation of the upstream gene, gene X, and identified two large gene X-secA transcripts. The 10-fold derepression of secA expression by protein export defects was at the translational level since no further increases in gene X or secA mRNA levels were detected during this period, and a secA-lacZ protein fusion but not an operon fusion was appropriately derepressed. Furthermore, overexpression of the SecA protein severely reduced expression of only the secA-lacZ protein fusion, indicating that SecA autogenously represses its own translation.