bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Expanded Lubricant Performance and Effects on Rotor Stability in Turbomachinery
Authors: Weaver Brian K. , Dimond Timothy W. , Kaplan Jason A. , Untaroiu Alexandrina , Clarens Andres F.
Published: October 2014

Gas-expanded lubricants (GELs) are tunable mixtures of synthetic oil and carbon dioxide that enable dynamic control of lubricant viscosity during bearing operation. This control can help reduce bearing power loss and operating temperatures while also providing direct control over bearing stiffness and damping, which can enhance rotordynamic performance. In this work, the bearing and rotordynamic performance of two representative high-speed machines was evaluated when different lubricants, including GELs, were supplied to the machine bearings. The machines chosen for this analysis, an eight-stage centrifugal compressor and a steam turbine-generator system, represent a wide range of speed and loading conditions encountered in modern turbomachinery. The fluids compared for machine performance were standard petroleum-based lubricants, polyol ester (POE) synthetic oils, and POE-based GELs. The performance simulations were carried out using a thermoelastohydrodynamic bearing model, which provided bearing stiffness and damping coefficients as inputs to finite element rotordynamic models. Several bearing performance metrics were evaluated including power loss, operating temperature, film thickness, eccentricity, and stiffness and damping coefficients. The rotordynamic analysis included an evaluation of rotor critical speeds, unbalance response, and stability. Bearing performance results for the compressor showed a 40% reduction in power loss at operating speed when comparing the GEL to the petroleum-based lubricant. The GEL-lubricated compressor also exhibited lower operating temperatures with minimal effects on film thickness. GELs were also predicted to produce lower bearing stiffness when compared to standard fluids in the compressor. Rotordynamic results for the compressor showed that the fluid properties had only minor effects on the unbalance response, while GELs were found to increase the stability margin by 43% when compared with standard fluids. The results from the turbine-generator system also demonstrated increases in low-speed bearing efficiency with the use of GELs, though at higher speeds the onset of turbulent flow in the GEL case offset these efficiency gains. Rotordynamic results for this system showed a contrast with the compressor results, with the GELs producing lower stability margins for a majority of the modes predicted due to increased bearing stiffness in the high-speed turbine bearings and negative stiffness in the lightly loaded, low-speed pinion bearings. These results suggest that GELs could be beneficial in providing control over a wide range of machine designs and operating conditions and that some machines are especially well suited for the tunability that these fluids impart.
Novel Open Circuit Displacement Control Architecture in Heavy Machinery
Authors: Ivantysyn Roman , Weber Jürgen
Published: October 2014

Motivated by the ever-stricter demands by lawmakers to lower emissions of mobile machinery and increasing fuel prices, mobile machinery has gone through a paradigm shift. Fuel efficiency has become a major selling point of machine producers. Even the heavy machinery branch, which is mainly dominated by reliability, productivity and serviceability, has started to feel this change. Hydraulic systems of large scale, as can be found in mining excavators, have typically been based on simplicity and durability. Typical architectures are open-center hydraulic systems, which were designed with robustness and productivity in mind; however they lack competiveness with other hydraulic systems in terms of energy efficiency.

Displacement control has shown promising potential especially in multi-actuator machines such as excavators. The technology has so far been demonstrated in closed circuit applications on small-scale machines (below 30 t). Large scale excavators however should in general be more suitable for displacement control due to their relatively small hydraulic component cost compared to the machine and operating cost, larger energy recovery potential due to larger mass movement, more flexibility in space management and greater hydraulic power installed. Large machines feature already several smaller pumps instead of a single large pump, which is important with respect to the fact that displacement control is based on one pump per actuator. A challenge for displacement control on large-scale machinery is handling their high volumetric flow-demands on the system. Today many large excavators feature a float valve, which short-circuits the cylinder chambers and ensures rapid lowering of the attachment under aiding load. Float valves ensure fast cycle times and are essential for high productivity, however incorporating this feature in displacement control is a challenge, especially in closed circuit systems.

Open circuit displacement control systems have greater flexibility than closed circuit solutions in working with float-valves and dealing with the high volumetric flows. Additionally the open circuit architecture is ideal for pump-flow-sharing, the strategy to connect two or more pumps with one actuator, which can be practiced when not all actuators move at the same time.

This paper compares displacement control in open circuit form with valve-controlled actuation in a mining excavator and shows several fuel saving potentials. The Open Center system was simulated and results were validated with measurements. The proposed open circuit displacement control solutions are implemented virtually and replace the valve-controlled system. Components and system-architecture were carefully chosen in order to ensure reliability, minimal component changes and redundancy that compare to the robustness of today’s system.
Development of an Energy Saving Hydraulic Stepper Drive
Authors: Gradl Christoph , Kovacic Ivo , Scheidl Rudolf
Published: October 2014

Stepper drives can realize quite precise, incremental motions without position sensors. Sensorless hydraulic motion control is strongly demanded by industry and, therefore, is an established idea in hydraulics for a while. Some concepts have been proposed in the past and a few of them have also been realized and applied in specific cases. But it is expected that digital hydraulics — due to its intrinsic discrete nature — can create new, more advantageous hydraulic versions of stepper drives.

In this paper, a new stepper drive is presented and investigated. It creates the steps by fixed fluid quanta generated by a so called digital flow unit. That unit is realized by a hydraulic cylinder-piston unit which displaces a defined fluid quantum by each limited forward stroke of that piston. The unit is controlled by a fast switching valve which connects the piston areas alternately with the pressure-, tank- and output-line. The return motion is generated by a return spring. Energy saving is accomplished by storing the supply pressure surplus intermediately in the kinetic energy of the piston and converting that energy to displace part of the quantum to the consumer line without hydraulic energy from the supply line. Different detail concepts of this stepper drive are theoretically assessed.

The transient behavior, the performance characteristics and the energy efficiency of a preferred concept are investigated by mathematical modeling and simulation. Furthermore, the main system parameters are identified and corresponding basic dimensioning rules are presented. In a second step, the influence of finite switching times of the valves, the hydraulic impedances of the various flow channels and of the dead volumes and the dynamical properties of the hydraulic cylinder attached to the device, are discussed.
Research on Three-Variable Control Technology of Seismic Simulating Shaking Tables
Authors: Luan Qiangli , Chen Zhangwei , Mao He
Published: October 2014

The seismic simulating shaking table is a typical electro-hydraulic servo test system and is controlled by a servo valve. The test system is widely used in the structural anti-seismic test. The seismic simulating shaking table usually has a low frequency response and a low damping which greatly limit its application for the wide bandwidth test. To further expand the bandwidth of the seismic simulating shaking table and increase its damping TVC (three-variable control) algorithm is proposed. In this paper, we research the TVC (three-variable control) algorithm for the seismic simulating shaking table, and also analyze its correction actions on the system characteristics of the shaking table achieved by both the TVC feedback and TVC feedforward loops. Then we further verify the improvement effects on the system’s frequency response characteristics of the shaking table taken by the TVC algorithm. The algorithm can expand the system bandwidth by introducing a velocity feedback and can increase the system damping by introducing an acceleration feedback. The TVC feedforward loop can eliminate the system poles near to the imaginary axis of system’s closed-loop transfer function and can also further expand the system bandwidth. Finally, we conduct two types of tests on a seismic simulating shaking table: sine sweep tests and seismic waveform replication tests. The results of the sine sweep tests show that the TVC algorithm can effectively improve the system’s frequency response characteristics of the shaking table and also improve its response speed. And the results of the seismic waveform replication tests show that the TVC algorithm can improve the replication accuracy of the seismic waveform.
Dynamics of Transmission Line Junctions: Comparison of CFD Results Against Measurements
Authors: Fries Clemens , Manhartsgruber Bernhard
Published: October 2014

Computational Fluid Dynamics (CFD) has become a valuable tool in the development of fluid power components due to its ability to model flows in complex geometries where simple analytical models are difficult to apply. The downside of CFD is the high computational cost of the method which prevents the application to whole fluid power systems. However, large parts of such systems can usually be modelled by more simple approaches like transmission line modelling. A coupled approach for a simple transmission line system is shown in this paper: Cylindrical parts of the flow domain are modelled with a spatially one-dimensional transmission line model augmented with frequency-dependent friction. The geometrically more complex intersections of cylindrical geometries like elbow joints and T-junctions are treated with a CFD solver in the Open-FOAM system. The simulation results from this coupled model are compared against a set of measurements from a test rig for elbow joints where cylindrical transmission line sections are connected at an angle of 90 degrees.
Experimental Investigation on the Helmholtz Hydraulic Silencer With Flat Cylindrical Vessel Configuration
Authors: Kuribayashi Tetsuya , Ichiyanagi Takayoshi , Nishiumi Takao
Published: October 2014

The Helmholtz type of hydraulic silencer is known as one of the most practical silencers. The silencer consists of a neck and a cylindrical vessel. A distinctive characteristic of the Helmholtz of hydraulic silencer is that the effective range of attenuation frequency is very limited. The maximum attenuation performance can be obtained at the resonant frequency because the Helmholtz resonance phenomenon is utilized. Therefore, it is very important to estimate the resonant frequency precisely at the design stage. In the design case that the length of cylindrical vessel becomes close to the diameter, i.e. the ratio of the length and diameter is nearly equal to 1.0, the resonant frequency of the existing model begins to deviate from the experimental results and this disparity increases with a decrease in the ratio of length and diameter. The purpose of this research is to clarify the influence of geometry on the attenuation characteristics of a Helmholtz type hydraulic silencer. In particular, a new mathematical model is proposed, that considers the flow for the radial direction of cylindrical vessel in the design case where the ratio is small. The transmission loss characteristics of the Helmholtz type hydraulic silencer are investigated theoretically for both the proposed model and existing model. These models are evaluated by experimental examinations in which the ratio is varied.
Advanced Hydraulically Actuated Patient Transfer Assist Device
Authors: Humphreys Heather C. , Book Wayne J.
Published: October 2014

A new, advanced patient transfer device is being developed for moving mobility limited patients, for example, from a wheelchair to a bed or a floor into a chair. Current market patient lift devices are antiquated and insufficient for customer needs, with only one actuated degree of freedom. The high power to size ratio of hydraulic actuation makes it suitable for moving larger, heavier patients. We have developed a prototype pump-controlled hydraulically actuated patient transfer device that is more maneuverable and agile, using multiple actuated degrees of freedom. We are also working toward developing a more intuitive and safe caretaker interface and control strategy.

We have performed an extensive needs assessment; these are a few associated key design requirements relevant to this presented work. A compact package is needed for ease of maneuvering the patient around obstacles in an uncertain environment. The device is capable of producing large forces, so it is desirable for the controller to minimize any unintentional large external contact forces, or provide force feedback. In this system, the caretaker and device work together to maneuver a complex payload, a human body; the operator’s mental workload must be minimized. With humans in the device workspace, safety and stability are necessary, including environment interactions.

This new application presents several challenges related to the hydraulic control. First, we are using a separate bidirectional fixed displacement pump with a reversible brushed DC motor for each degree of freedom. The low level control involves obtaining desirable response from each motor-pump-actuator system, while compensating for significant static friction. At a higher level, we are testing several approaches to attain the desired intuitive control and desired dynamics, and minimize the operator workload. First, we are developing a coordinated control using a force input, such that the operator simply pushes on the device in the desired direction of motion. We are testing several different controllers to attain the desired dynamics. This paper presents the design of the machine, the proposed control structures as applied to this application, operator interface options, some preliminary results, and future work.
Predictive Friction Compensation for Control of Pneumatic Actuators
Authors: Daepp Hannes G. , Book Wayne J.
Published: October 2014

Pneumatic actuators possess several attractive qualities: high power and force density, potentially adaptable compliance, and clean, safe, and low cost actuation. However, control of pneumatic actuators has proven difficult, limited by inherent compliance of the actuator, nonlinear and discontinuous third order dynamics, and friction. Stiction and compliance lead to a sandwiched nonlinearity that causes stick-slip and can cause significant tracking error and even instability. A broadly applicable method of friction compensation is addition of a feedforward term updated from a friction estimate at each time step. Since pneumatic dynamics are slow, achievable compensation can be insufficient. In this work, friction is estimated over a prediction horizon and then input into a model-based predictive controller as an offset term, so that compensation is planned and optimal over the prediction horizon. The controller is tested in simulation. Results are compared to control using instantaneous compensation and are characterized based on performance.
Construction and Experimental Research on Plastic Cycloidal Gears Used in Gerotor Pumps
Authors: Krawczyk Justyna , Stryczek Jarosław
Published: October 2014

Paper presents the construction and results of experimental research of gerotor pump with gears made of POM and PPS. Research program included verification of design factors (axial and radial clearance), operational factors (impact of speed, pressure and temperature on the pump characteristics) and definition of durability characteristics. Results of research proves that the pump with gears made of plastics can operate at high speeds (up to 4000 rpm), at temperature of the working fluid in the range 25°C – 50°C, with the working pressure at the outlet of the pump 4 MPa. Presented results of long-term tests, shows that the pump with gears made of plastics worked for 40 hours maintaining a constant level of efficiency Q = 12.5 dm3, which represents 80% of the theoretical volumetric efficiency.
A Numerical Procedure to Design the Optimal Axial Balance of Pressure Compensated Gear Machines
Authors: Thiagarajan Divya , Vacca Andrea
Published: October 2014

This paper presents an innovative numerical procedure to determine the optimal balancing area of lateral bushes in external gear pumps or motors. In pressure compensated designs of external gear machines, the lateral bushes perform the important functions of sealing the tooth space volumes while they transfer fluid from the inlet to the outlet port. In normal operating conditions, a lubricating gap exists between the lateral bush and the gear permitting to minimize losses due to shear stress and leakage. These conditions are found by determining proper balancing areas at the side of the bushes not facing the gears, in which the pressure of the high pressure port is properly established. This problem is also known as “axial balance” of external gear machines.

To determine the optimal axial balance which minimizes the power losses associated with the lubricating gap in all operating conditions, all the static and hydrodynamic forces acting on the lateral bushes have to be considered. This delicate aspect of external gear units design is usually addressed through empirical procedures; while in this paper an automatic numerical procedure is presented. The proposed method is based on the solution of the force balance of the lateral bushes, taking into account all force components, including the hydrodynamic terms due to the relative inclination between bushes and gears and material deformation.

After detailing the procedure, the paper describes its potentials by showing the advantages arising from the optimization of the axial balance of a particular external gear pump for fluid power applications.
Combined Air Supply at Fuel Pump Entrance
Authors: Gafurov Salimzhan , Rodionov Leonid , Gimadiev Asgat
Published: October 2014

Previous research has shown that aviation fuel pumps, which consist of a screw and centrifugal wheels are the most loaded units of the gas turbine engines. Thus a fuel pump is the key component that limits the reliability and endurance of the fuel system and, as a result, of the whole engine.

This paper describes the results of CFD simulations of the process getting free gas to enter the combined pump. The CFD analysis has been used to calculate an unsteady three-dimensional viscous flow of multi-component fluid in the fuel pump. The calculations have been used to determine unsteady loads of fuel pump in different operating modes. To examine the efficiency of the CFD analysis, we conducted a series of experiments. The experimental results proved the accuracy of the numerical model. The results can help to develop measures for the reduction of dynamic loads in aviation fuel pumps in case where combined air is at entrance to pump.
An Investigation of the Impact of Micro Surface on the Cylinder Block/Valve Plate Interface Performance
Authors: Chacon Rene , Ivantysynova Monika
Published: October 2014

Lubricating gaps are the primary source of energy dissipation in axial piston machines of swash plate-type. One of these lubricating gaps is designated as the cylinder block/valve plate interface, and is one of the most critical design elements for this type of positive displacement machine. In the past, extensive work has been done at Maha Fluid Power Research Center both to model this interface and to study the effects of micro-surface shaping on the valve plate. This paper presents a more in-depth investigation into optimizing valve plate micro-surface shaping (both by altering the number and amplitude of waves) in order to achieve a fluid film thickness that compromises between leakage and torque loss, minimizes power loss in the cylinder block/valve plate interface, and maximizes machine efficiency.
Energy Saving Potential of a Hydrostatic Drivetrain With Variable Charge Pump
Authors: Zavadinka Peter , Grepl Robert
Published: October 2014

This paper deals with the power saving prediction of hydrostatic drivetrains achieved with a variable roller charge pump. Focusing on the charge pump in a hydrostatic transmission, shows, that fixed pumps don’t act in all operating conditions very efficient. The charge pump delivers in some conditions a higher flow than required. The unused energy is dissipated into heat. According to this assumption, using variable charge pump is another possible way to save energy. In the end it means reduce fuel consumption.

Generally, the power saving potential is depending on the application, but two main factors can be highlighted: the first one is the charge pump size and the second is the application of an intelligent loop flushing system. The standard loop flushing system demands more cooling flow than required in some conditions, but a variable charge pump is able to more efficiently cover demands of intelligent loop flushing system.

The power saving potential will be analyzed for two different example systems/vehicles in their typical operation conditions. All analyses are made with simulation models, which include simplified thermal behavior of the hydraulic circuit, also. The results in this paper confirmed the power saving potential for different applications with bigger charge pumps with an intelligent loop flushing function could be the most interesting applications.
Analysis of Signals and Power Flow in a Digital Hydraulic Multi Actuator Aplication
Authors: Karvonen Matti , Linjama Matti , Heikkilä Mikko , Huhtala Kalevi
Published: October 2014

A combination of digital hydraulic four notch control valves and the digital hydraulic power management system (the DHPMS) has many controller levels, both parallel and series. The DHPMS is a multi-port sink/source of hydraulic power. Digital hydraulic valves are used to control the actuators. Both the DHPMS and the digital valves are based on the idea that all complexity is in the software and the hardware is based on arrays of mechanically simple base units. Controllers work together merging into a power flow system where the whole power transfer line is controlled from a single pumping piston within the pump to the movement of the tip of the boom. Or vice versa, if the operating conditions allow negative power to be routed backwards. In the paper certain measurements are looked into; second by second and a signal by a signal. The paper presents and verifies functionality of the novel combination of technologies. How signals flow in the controllers and how they actually control the power flow in the system is explained. The test system is a two-actuator boom, and as two is the smallest example of multi, the controller is designed by a simple and robust control method.
Modelling and Simulation of the Hydraulic Circuit of an Agricultural Tractor
Authors: Pintore Francesco , Borghi Massimo , Morselli Riccardo , Benevelli Alessandro , Zardin Barbara , Belluzzi Francesco
Published: October 2014

This work aims to analyse a complete hydraulic system of a medium size agricultural tractor, in order to perform an energy dissipation analysis and to test possible alternative configurations and solutions. The fuel consumption and energy dissipation in off-road vehicles have infact become a key feature, given the great attention devoted to the need of reducing pollutant emissions, in order to satisfy the future emission limits. Standard and alternative architecture configurations are modelled and compared on the basis of the power consumption to perform the same duty cycle. Among the results, it is worth highlighting that a relevant percentage of energy may be saved with simple modifications in the hydraulic power generation group.
Boom Motion Control Using Pressure Control Valve
Authors: Sørensen Jesper K. , Hansen Michael R. , Ebbensen Morten K.
Published: October 2014

This paper focuses on the reduction in oscillations created by counterbalance valves by using a proportional pressure control valve. The motion control of a cylinder boom is presented using this valve, which is a 4/3-way directional control valve with the main spool in series with an upstream compensator. The input to the valve control is a main spool position reference and, indirectly, the compensator downstream pressure. This gives a different flow gain and, therefore, a different feedforward scheme as compared to applications with the more common pressure compensated flow control valve.

The theory behind the pressure control valve is presented and applied to both a theoretical and experimental implementation of closed loop motion control of the jib boom of a commercial vehicle loader crane.
A General Auto-Tuning Method for Active Vibration Damping of Mobile Hydraulic Machines
Authors: Ritelli Guido Francesco , Vacca Andrea
Published: October 2014

This paper presents an innovative approach towards the active vibration damping of mobile hydraulic machines. The authors’ research group recently introduced a novel control strategy based on pressure feedback and on an optimization procedure. The success of the optimization lies on the efficient quantification of the vibration extend which is the objective to be minimized. This paper addresses the definition of the objective function introducing a new method which does not require a priori knowledge of the working cycle. This approach enables the control strategy to be potentially applied to any kind of working scenario and does not require the intervention of a control designer.

The results presented in this paper show that the novel method is able to effectively attenuate the undesired oscillations while not affecting the actuator velocity.
Characterization of tungsten films and their hydrogen permeability
Authors: Nemanič Vincenc , Kovač Janez , Lungu Cristian , Porosnicu Corneliu , Zajec Bojan
Published: October 2014

Prediction of tritium migration and its retention within fusion reactors is uncertain due to a significant role of the structural disorder that is formed on the surface layer after plasma exposure. Tungsten films deposited by any of the suitable methods are always disordered and contain a high density of hydrogen traps. Experiments on such films with hydrogen isotopes present a suitable complementary method, which improves the picture of the hydrogen interaction with fusion relevant materials. The authors report on the morphology, composition, and structure of tungsten films deposited by the thermionic vacuum arc method on highly permeable Eurofer substrates. Subsequently, hydrogen permeation studies through these films were carried out in a wide pressure range from 20 to 1000 mbars at 400 °C. The final value of the permeation coefficient for four samples after 24 h at 400 °C was between P = 3.2 × 10−14 mol H2/(m s Pa0.5) and P = 1.1 × 10−15 mol H2/(m s Pa0.5). From the time evolution of the permeation flux, it was shown that diffusivity was responsible for the difference in the steady fluxes, as solubility was roughly the same. This is confirmed by XRD data taken on these samples.
Fabrication of high-contrast gratings for a parallel spectrum splitting dispersive element in a concentrated photovoltaic system
Authors: Yao Yuhan , Liu He , Wu Wei
Published: October 2014

High-contrast gratings are designed and fabricated and their application in a parallel spectrum splitting dispersive element is proposed that is found to have the potential to improve the solar conversion efficiency of a concentrated photovoltaic system. This proposed system will also lower solar cell cost in the concentrated photovoltaic systems by replacing the expensive tandem solar cells with cost-effective single-junction solar cells. The structures and parameters of the high-contrast gratings for the dispersive element are numerically optimized, and a large-area fabrication is experimentally demonstrated using nanoimprint lithography and dry etching. Both the quality of the material and the performance of the fabricated device are experimentally characterized and discussed.
Auditory motivated front-end for noisy speech using spectro-temporal modulation filtering
Authors: Ganapathy Sriram , Omar Mohamed
Published: October 2014

The robustness of the human auditory system to noise is partly due to the peak preserving capability of the periphery and the cortical filtering of spectro-temporal modulations. In this letter, a robust speech feature extraction scheme is developed that emulates this processing by deriving a spectrographic representation that emphasizes the high energy regions. This is followed by a modulation filtering step to preserve only the important spectro-temporal modulations. The features derived from this representation provide significant improvements for speech recognition in noise and language identification in radio channel speech. Further, the experimental analysis shows congruence with human psychophysical studies.
The Effects of Walking on Gastrocnemius Cooling During an Ice Bag Treatment
Authors: Guzzo Stephanie J. , Yeargin Susan W. , Carr Jeffery S. , Demchak Timothy J. , Edwards Jeffrey E.
Published: October 2014

Context:

Many athletic trainers use “ice to go” to treat their athletes. However, researchers have reported that icing a working muscle may negate intramuscular (IM) cooling.

Objective:

The purpose of our study was to determine the length of time needed to cool the gastrocnemius while walking followed by rest.

Design:

A randomized crossover study design was used.

Setting:

Exercise Physiology Laboratory.

Patients or Other Participants:

Nine healthy, physically active males and females (males 5, females 4; age 24.0 ± 2.0 years; height 174.0 ± 8.0 cm; weight 86.3 ± 6.5 kg; skinfold taken at center of gastrocnemius greatest girth, R leg 20.3 ± 4.4 mm, L leg 19.6 ± 4.1 mm) without lower extremity injury or cold allergy volunteered to complete the study.

Intervention:

Participants randomly experienced three treatment conditions on separate days: rest (R), walk for 15 minutes followed by rest (W15R), or walk for 30 minutes followed by rest (W30R). During each treatment, participants wore a 1 kg ice bag secured to their right gastrocnemius muscle. Participants walked at a 4.5km/hr pace on a treadmill during the W15R and W30R trials.

Main Outcome Measures:

A 1 × 3 within groups ANOVA was used to determine the effect of activity on cooling time needed for the gastrocnemius temperature to decrease 6 °C below baseline.

Results:

The R condition cooled faster (25.9 ± 5.5 min) than both W15R (33.7 ± 9.3 min; P = .002) and W30R (49.4 ± 8.4 min; P < .001). Average time to decrease 6 °C after W15R was 18.7 ± 9.3 minutes and after W30R was 19.4 ± 8.4 minutes.

Conclusions:

Clinicians should instruct their patients to stay and ice or to keep the ice on for an additional 20 minutes after they stop walking and begin to rest.
Operative Elbow Injuries Among Hungarian Elite Wrestlers
Authors: Molnár Szabolcs Lajos , Hidas Péter , Kocsis György , Rögler Gábor , Balogh Péter , Farkasházi Miklós , Lang Péter
Published: October 2014

Background:

Upper extremity injuries are common in wrestling, most of which do not require surgery.

Methods:

We retrospectively documented the case histories of six elite wrestlers who sustained elbow injuries that required surgical treatment, three of which involved reinjury and another surgical procedure.

Results:

All but one of the six initial injuries were associated with a defensive maneuver. Reinjury was more common for freestyle wrestling than for Greco-Roman style. The average time between the initial elbow injury and surgical intervention was 22 months. One-half of the wrestlers with elbow injuries that required surgery were reinjured and underwent revision surgery.

Conclusions:

All of the elite wrestlers waited for a long period of time before receiving surgery for the initial injury, and the reinjury rate was high.
Comparison of Plantar Flexor Musculotendinous Stiffness, Geometry, and Architecture in Male Runners With and Without a History of Tibial Stress Fracture
Authors: Pamukoff Derek N. , Blackburn J. Troy
Published: October 2014

Greater lower extremity joint stiffness may be related to the development of tibial stress fractures in runners. Musculotendinous stiffness is the largest contributor to joint stiffness, but it is unclear what factors contribute to musculotendinous stiffness. The purpose of this study was to compare plantar flexor musculotendinous stiffness, architecture, geometry, and Achilles tendon stiffness between male runners with and without a history of tibial stress fracture. Nineteen healthy runners (age = 21 ± 2.7 years; mass = 68.2 ± 9.3 kg; height = 177.3 ± 6.0 cm) and 19 runners with a history of tibial stress fracture (age = 21 ± 2.9 years; mass = 65.3 ± 6.0 kg; height = 177.2 ± 5.2 cm) were recruited from community running groups and the university’s varsity and club cross-country teams. Plantar flexor musculotendinous stiffness was estimated from the damped frequency of oscillatory motion about the ankle follow perturbation. Ultrasound imaging was used to measure architecture and geometry of the medial gastrocnemius. Dependent variables were compared between groups via one-way ANOVAs. Previously injured runners had greater plantar flexor musculotendinous stiffness (P < .001), greater Achilles tendon stiffness (P = .004), and lesser Achilles tendon elongation (P = .003) during maximal isometric contraction compared with healthy runners. No differences were found in muscle thickness, pennation angle, or fascicle length.
Prevalence of small-scale jets from the networks of the solar transition region and chromosphere
Authors: Tian H. , DeLuca E. E. , Cranmer S. R. , De Pontieu B. , Peter H. , Martínez-Sykora J. , Golub L. , McKillop S. , Reeves K. K. , Miralles M. P. , McCauley P. , Saar S. , Testa P. , Weber M. , Murphy N. , Lemen J. , Title A. , Boerner P. , Hurlburt N. , Tarbell T. D. , Wuelser J. P. , Kleint L. , Kankelborg C. , Jaeggli S. , Carlsson M. , Hansteen V. , McIntosh S. W.
Published: October 2014

As the interface between the Sun’s photosphere and corona, the chromosphere and transition region play a key role in the formation and acceleration of the solar wind. Observations from the Interface Region Imaging Spectrograph reveal the prevalence of intermittent small-scale jets with speeds of 80 to 250 kilometers per second from the narrow bright network lanes of this interface region. These jets have lifetimes of 20 to 80 seconds and widths of ≤300 kilometers. They originate from small-scale bright regions, often preceded by footpoint brightenings and accompanied by transverse waves with amplitudes of ~20 kilometers per second. Many jets reach temperatures of at least ~10
5
kelvin and constitute an important element of the transition region structures. They are likely an intermittent but persistent source of mass and energy for the solar wind.
On the prevalence of small-scale twist in the solar chromosphere and transition region
Authors: De Pontieu B. , Rouppe van der Voort L. , McIntosh S. W. , Pereira T. M. D. , Carlsson M. , Hansteen V. , Skogsrud H. , Lemen J. , Title A. , Boerner P. , Hurlburt N. , Tarbell T. D. , Wuelser J. P. , De Luca E. E. , Golub L. , McKillop S. , Reeves K. , Saar S. , Testa P. , Tian H. , Kankelborg C. , Jaeggli S. , Kleint L. , Martinez-Sykora J.
Published: October 2014

The solar chromosphere and transition region (TR) form an interface between the Sun’s surface and its hot outer atmosphere. There, most of the nonthermal energy that powers the solar atmosphere is transformed into heat, although the detailed mechanism remains elusive. High-resolution (0.33–arc second) observations with NASA’s Interface Region Imaging Spectrograph (IRIS) reveal a chromosphere and TR that are replete with twist or torsional motions on sub–arc second scales, occurring in active regions, quiet Sun regions, and coronal holes alike. We coordinated observations with the Swedish 1-meter Solar Telescope (SST) to quantify these twisting motions and their association with rapid heating to at least TR temperatures. This view of the interface region provides insight into what heats the low solar atmosphere.
In optical pumping, less can be more
Authors: Schwefel Harald G. L.
Published: October 2014

Creating loss in one optical resonator can initiate lasing in its coupled partner
Looking closer at the Sun
Authors: Harra Louise K.
Published: October 2014

The space-based IRIS telescope provides a new window to view the solar atmosphere
For Venezuelan academics, speaking out is risky business
Authors: Wade Lizzie
Published: October 2014

Government attacks some, snares many in red tape.
Light loophole wins laurels
Authors: Clery Daniel
Published: October 2014

Chemistry prize winners pushed microscopes past supposed limit.
Regulating industry's big boys
Authors: Rabesandratana Tania
Published: October 2014

French economist Jean Tirole is honored for his analyses of oligopolies.
Thermostable Cross-Protective Subunit Vaccine against Brucella Species
Authors: Cherwonogrodzky John W. , Barabé Nicole D. , Grigat Michelle L. , Lee William E. , Poirier Robert T. , Jager Scott J. , Berger Bradley J.
Published: October 2014

A subunit vaccine candidate was produced fromBrucella suis145 (biovar 4; expressing both the A antigen ofBrucella abortusand the M antigen ofBrucella melitensis). The preparation consisted mostly of polysaccharide (PS; >90% [wt/wt]; both cell-associated PS and exo-PS were combined) and a small amount of protein (1 to 3%) with no apparent nucleic acids. Vaccinated mice were protected (these had a statistically significant reduction in bacterial colonization compared to that of unvaccinated controls) when challenged with representative strains of threeBrucellaspecies most pathogenic for humans, i.e.,B. abortus,B. melitensis, andB. suis. As little as 1 ng of the vaccine, without added adjuvant, protected mice againstB. suis145 infection (5 × 105CFU), and a single injection of 1 μg of this subunit vaccine protected mice fromB. suis145 challenge for at least 14 months. A single immunization induced a serum IgG response toBrucellaantigens that remained elevated for up to 9 weeks. The use of heat (i.e., boiling-water bath, autoclaving) in the vaccine preparation showed that it was thermostable. This method also ensured safety and security. The vaccine produced was immunogenic and highly protective against multiple strains ofBrucellaand represents a promising candidate for further evaluation.
Establishment of Quantitative PCR (qPCR) and Culture Laboratory Facilities in a Field Hospital in Benin: 1-Year Results
Authors: Marion Estelle , Ganlonon Line , Claco Eric , Blanchard Simon , Kempf Marie , Adeye Ambroise , Chauty Annick
Published: October 2014

No simple diagnostic tool is available to confirm
Mycobacterium ulcerans
infection, which is an emerging disease reported in many rural areas of Africa. Here, we report the 1-year results of a hospital laboratory that was created in an area of endemicity of Benin to facilitate the diagnosis of
M. ulcerans
infection.
Screening Rectal Swabs for Carbapenemase Genes
Authors: van der Zee Anneke , Roorda Lieuwe , Bosman Gerda , Ossewaarde Jacobus M.
Published: October 2014

In an outbreak setting, we screened 16,296 samples from 3,644 patients by PCR for the presence of
bla
OXA-48
,
bla
VIM
,
bla
IMP
,
bla
NDM
, and
bla
KPC
. The
bla
OXA-48
gene was found in samples from 43 patients infected with 9 different species of
Enterobacteriaceae
. Five patients had
Pseudomonas aeruginosa
isolates containing
bla
VIM
. The negative predictive value of screening was 100%, and the positive predictive value was 86%.
Acid Exposure Induces Multiplication of Salmonella enterica Serovar Typhi
Authors: Ahirwar Suneel Kumar , Pratap Chandra Bhan , Patel Saurabh Kumar , Shukla Vijay K. , Singh Indarjeet Gambhir , Mishra Om Prakash , Kumar Kailash , Singh Tej Bali , Nath Gopal
Published: October 2014

Salmonella enterica
serovar Typhi faces several environmental stresses while going through the stomach (acidic pH) to the small intestine (basic pH) and intracellularly in macrophages (acidic pH) in humans. The acidic pH followed by alkaline pH in the small intestine might be responsible for expression of certain stress-induced genes, resulting in not only better survival but also induction of multiplication and invasion of the bacterium in the small intestine. Based on this hypothesis, we developed a process wherein we exposed the blood, urine, and stool specimens from 90 acute typhoid fever patients and 36 chronic typhoid carriers to acidic pH to see the effect on isolation rate of
S
. Typhi. About 5 g of freshly passed unpreserved stool, a centrifuged deposit of 15 ml of urine, and 5 ml of blood clot were subjected to 5 ml of Luria-Bertani (LB) broth (pH 3.5) for 20 min, followed by enrichment in bile broth-selenite F broth. When the combined isolation from all 3 specimens, i.e., blood, urine, and stool, after acid exposure was considered, a total of 77.7% of the acute typhoid patients were observed to be positive for the isolation of the
S
. Typhi serotype, compared to 8.8% by the conventional method. Similarly, 42% (15/36) of chronic carriers yielded positive for
S
. Typhi growth after acid exposure, compared to 5.5% (2/36) by the conventional method. It therefore can be concluded that acid shock triggers the multiplication of the bacteria, resulting in better isolation rates from blood clot, stool, and urine specimens.
Proinflammatory Effects of Interferon Gamma in Mouse Adenovirus 1 Myocarditis
Authors: McCarthy Mary K. , Procario Megan C. , Twisselmann Nele , Wilkinson J. Erby , Archambeau Ashley J. , Michele Daniel E. , Day Sharlene M. , Weinberg Jason B.
Published: October 2014

Adenoviruses are frequent causes of pediatric myocarditis. Little is known about the pathogenesis of adenovirus myocarditis, and the species specificity of human adenoviruses has limited the development of animal models, which is a significant barrier to strategies for prevention or treatment. We have developed a mouse model of myocarditis following mouse adenovirus 1 (MAV-1) infection to study the pathogenic mechanisms of this important cause of pediatric myocarditis. Following intranasal infection of neonatal C57BL/6 mice, we detected viral replication and induction of interferon gamma (IFN-γ) in the hearts of infected mice. MAV-1 caused myocyte necrosis and induced substantial cellular inflammation that was composed predominantly of CD3+T lymphocytes. Depletion of IFN-γ during acute infection reduced cardiac inflammation in MAV-1-infected mice without affecting viral replication. We observed decreased contractility during acute infection of neonatal mice, and persistent viral infection in the heart was associated with cardiac remodeling and hypertrophy in adulthood. IFN-γ is a proinflammatory mediator during adenovirus-induced myocarditis, and persistent adenovirus infection may contribute to ongoing cardiac dysfunction.

IMPORTANCEStudying the pathogenesis of myocarditis caused by different viruses is essential in order to characterize both virus-specific and generalized factors that contribute to disease. Very little is known about the pathogenesis of adenovirus myocarditis, which is a significant impediment to the development of treatment or prevention strategies. We used MAV-1 to establish a mouse model of human adenovirus myocarditis, providing the means to study host and pathogen factors contributing to adenovirus-induced cardiac disease during acute and persistent infection. The MAV-1 model will enable fundamental studies of viral myocarditis, including IFN-γ modulation as a therapeutic strategy.
The Human CD8
+
T Cell Responses Induced by a Live Attenuated Tetravalent Dengue Vaccine Are Directed against Highly Conserved Epitopes
Authors: Weiskopf Daniela , Angelo Michael A. , Bangs Derek J. , Sidney John , Paul Sinu , Peters Bjoern , de Silva Aruna D. , Lindow Janet C. , Diehl Sean A. , Whitehead Stephen , Durbin Anna , Kirkpatrick Beth , Sette Alessandro
Published: October 2014

The incidence of infection with any of the four dengue virus serotypes (DENV1 to -4) has increased dramatically in the last few decades, and the lack of a treatment or vaccine has contributed to significant morbidity and mortality worldwide. A recent comprehensive analysis of the human T cell response against wild-type DENV suggested an human lymphocyte antigen (HLA)-linked protective role for CD8
+
T cells. We have collected one-unit blood donations from study participants receiving the monovalent or tetravalent live attenuated DENV vaccine (DLAV), developed by the U.S. National Institutes of Health. Peripheral blood mononuclear cells from these donors were screened in gamma interferon enzyme-linked immunosorbent spot assays with pools of predicted, HLA-matched, class I binding peptides covering the entire DENV proteome. Here, we characterize for the first time CD8
+
T cell responses after live attenuated dengue vaccination and show that CD8
+
T cell responses in vaccinees were readily detectable and comparable to natural dengue infection. Interestingly, whereas broad responses to structural and nonstructural (NS) proteins were observed after monovalent vaccination, T cell responses following tetravalent vaccination were, dramatically, focused toward the highly conserved NS proteins. Epitopes were highly conserved in a vast variety of field isolates and able to elicit multifunctional T cell responses. Detailed knowledge of the T cell response will contribute to the identification of robust correlates of protection in natural immunity and following vaccination against DENV.

IMPORTANCE
The development of effective vaccination strategies against dengue virus (DENV) infection and clinically significant disease is a task of high global public health value and significance, while also being a challenge of significant complexity. A recent efficacy trial of the most advanced dengue vaccine candidate, demonstrated only partial protection against all four DENV serotypes, despite three subsequent immunizations and detection of measurable neutralizing antibodies to each serotype in most subjects. These results challenge the hypothesis that seroconversion is the only reliable correlate of protection. Here, we show that CD8
+
T cell responses in vaccinees were readily detectable and comparable to natural dengue virus infection. Detailed knowledge of the T cell response may further contribute to the identification of robust correlates of protection in natural immunity and vaccination against DENV.