bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Investigation of Inlet Swirl in a Turbine Cascade
Authors: Schmid Gregor , Schiffer Heinz-Peter
Published: August 2013

New combustion concepts towards lean burn aim at reducing peak temperatures and therefore emissions, especially nitrogen oxides. High swirl is required in order to enhance the mixing of fuel and air and thus, improve combustion and flame stability. In a numerical investigation of a turbine vane cascade the effect of such inlet swirl on aerodynamic losses, secondary flow pattern and heat transfer is investigated.

The computations are conducted prior to particle image velocimetry and five-hole-probe measurements in a cascade of six vane passages and swirl generators upstream of each passage. The analysis covers three constituent parts: First, different swirl intensities are simulated which resemble the situation in a real combustion chamber. Second, different clocking positions are investigated — the swirl cores are either aligned with the vane leading edge or with midpassage — and finally, swirl orientation as clockwise, anticlockwise and counter rotating swirl is analysed. Two-dimensional inlet boundary conditions are applied to model the discrete swirl cores. Furthermore, a comparison with circumferentially averaged as well as with axial inflow conditions is made.

Increasing the swirl number at the inlet boundary results in reduced heat transfer coefficient within the vane passage and higher pressure loss. Heat transfer through vanes and endwalls is maximal if the swirl generators are aligned with the vane leading edge and counter rotating swirl.
Time-Resolved PIV Measurements of Turbulent Flow in Rotating Rib-Roughened Channel With Coriolis and Buoyancy Forces
Authors: Coletti Filippo , Cresci Irene , Arts Tony
Published: August 2013

The present contribution addresses the effect of Coriolis and buoyancy forces in a rotating rectangular channel having one wall provided with ribs perpendicular to the flow direction. Time-resolved PIV measurements are performed in a rotating facility where both the channel model and the measurement system rotate on a turntable at 134 rpm. Air is used as working fluid. The Reynolds number defined by the bulk velocity and the hydraulic diameter is 15000, and a rotation number of 0.38 is obtained both in clockwise and counter-clockwise sense. The ribbed wall, machined out of copper, is heated to a uniform temperature of about 100°C by means of electrical resistances. This allows to obtain a centrifugal buoyancy number of 0.31. Velocity fields are measured along the channel symmetry plane using a continuous laser diode and a high-speed camera. Both ensemble-averaged and time-resolved measurements are performed. In the latter case the realizations are acquired at 3.3 KHz, allowing to resolve the fine temporal flow scales. The effects of the rotational buoyancy with respect to the action of the Coriolis forces alone are highlighted. Particular attention is drawn to the extension of the separated area behind the rib, as well as to the length scales and time scales of the structures generated on the separated shear layer behind the ribs. Vortical structures are identified as regions of strong swirl having both spatial and temporal coherence. The rotational buoyancy near the heated wall affects strongly the physical characteristics, distribution and trajectory of such structures, which are critical for the turbulent transport and heat transfer.
Steady and Unsteady Modeling for Heat Transfer Predictions of High Pressure Turbine Blade Internal Cooling
Authors: Fransen Rémy , Gourdain Nicolas , Gicquel Laurent Y. M.
Published: August 2013

This work focuses on numerical simulations of flows in blade internal cooling system. Large Eddy Simulation (LES) and Reynolds-Averaged Navier Stokes (RANS) approaches are compared in a typical blade cooling related problem. The case is a straight rib-roughened channel with high blockage ratio, computed and compared for both a periodic and full spatial domains. The configuration was measured at the Von Karman Institute (VKI) using Particle Image Velocimetry (PIV) in near gas turbine operating conditions. Results show that RANS models used fail to predict the full evolution of the flow within the channels where massive separation and large scale unsteady features are evidenced. In contrast LES succeeds in reproducing these complex flow motions and both mean and fluctuating components are clearly improved in the channels and in the near wall region. Periodic computations are gauged against the spatial computational domain and results on the heat transfer problem are addressed.
Effect of Guide Vanes in the Tip Turn Region on Heat/Mass Transfer of Rotating Two-Pass Channel
Authors: Park Jun Su , Lee Dong Myeong , Lee Dong Hyun , Lee Sanghoon , Kim Beom Soo , Cho Hyung Hee
Published: August 2013

This study investigated convective heat transfer inside a rotating two-pass rectangular channel with guide vanes in the turning region. The objective was to determine the effect of the guide vanes on blade tip cooling. The channel had a hydraulic diameter of 26.67 mm and an aspect ratio of 5, and various guide vane configurations were used in the turning region. The Reynolds number, based on the hydraulic diameter, was held constant at 10,000 while the rotation number was 0.1. The detailed local heat transfer coefficients were determined through naphthalene sublimation using the heat and mass transfer analogy. The heat transfer was high on the trailing surface in the first-pass section and on the leading surface in the second-pass section. The heat transfer on leading and trailing surfaces increased in the rotating channel, but the heat transfer on the tip surface decreased. The peak heat transfer on the tip surface appeared in the middle of the first-pass corner due to the centrifugal force.
Heat Transfer Characteristics of an Angled Array Impinging Jet on a Concave Duct
Authors: Jung Eui Yeop , Park Chan Ung , Lee Dong Hyun , Kim Kyung Min , Woo Ta-kwan , Cho Hyung Hee
Published: August 2013

This study investigated the heat transfer characteristics of an array jet cooling system on a concave surface. Two types of injection holes were used: one for impinging jets normal to the impingement surface, and the other for angled impinging jets. For the normal jets, the jet Reynolds number (Re) based on the hole diameter varied from 3,000 to 10,000, and the height-to-diameter ratio (H/d) was fixed at 1.0. There were 15 injection holes positioned in a staggered 3×5 array. For the angled jets, Re was set to 5,000 and H/d was also fixed at 1.0. Naphthalene sublimation method was used to determine the heat transfer coefficients on the targeted plates. For normal impinging jet cooling, separate peaks were observed at the stagnation regions due to the curvature effect. Since a crossflow was generated by air spent from the jet arrays, the crossflow effect increased as it moved downstream. Due to the interaction between the crossflow and impinging jets, the peak values at the stagnation points increased downstream. The heat transfer coefficient on the targeted plate increased with Re. The average Sh of the angled jets was higher than that of the normal jets, as the obliquely impinging jet increased the mass flow rate and mass interaction between the jet impingement points.
Heat Transfer Measurements in a Leading Edge Geometry With Racetrack Holes and Film Cooling Extraction
Authors: Andrei Luca , Carcasci Carlo , Da Soghe Riccardo , Facchini Bruno , Maiuolo Francesco , Tarchi Lorenzo , Zecchi Stefano
Published: August 2013

An experimental survey on a state of the art leading edge cooling scheme was performed to evaluate heat transfer coefficients (HTC) on a large scale test facility simulating an high pressure turbine airfoil leading edge cavity. Test section includes a trapezoidal supply channel with three large racetrack impingement holes. On the internal surface of the leading edge, four big fins are placed in order to confine impingement jets. The coolant flow impacts the leading edge internal surface and it is extracted from the leading edge cavity through 24 showerhead holes and 24 film cooling holes. The aim of the present study is to investigate the combined effects of jet impingement and mass flow extraction on the internal heat transfer of the leading edge. A non uniform mass flow extraction was also imposed to reproduce the effects of pressure side and suction side external pressure. Measurements were performed by means of a transient technique using narrow band Thermo-chromic Liquid Crystals (TLC). Jet Reynolds number and crossflow conditions into the supply channel were varied in order to cover the typical engine conditions of these cooling systems (Rej = 10000–40000). Experiments were compared with a numerical analysis on the same test case in order to better understand flow interaction inside the cavity. Results are reported in terms of detailed 2D maps, radial-wise and span-wise averaged values of Nusselt number.
Multi-Color Techniques for Identification and Filtering of Burst Signals in Jet Engine Pyrometers
Authors: Estevadeordal Jordi , Wang Guanghua , Nirmalan Nirm , Harper Sean P. , Wang Anquan , Lewandowski Bradford , Rigney Joseph D.
Published: August 2013

A DARPA funded Multi-color Pyrometry (MCP) experiment was carried out on a government provided aircraft engine to study the nature of hot particulate bursts generated from the combustor at certain engine conditions. These bursts of hot particulates lead to intermittent high-voltage signal output from the line-of-sight (LOS) pyrometer which is ultimately detected and used by the onboard digital engine controller (DEC). The investigation used a high-speed MCP system designed to detect bursts and identify their properties. Results of the radiant temperature, multi-color temperature and apparent emissivity are presented. The results indicated that the apparent emissivity calculated during the signal burst was lower than that of the blade. The root cause for the signal burst was identified as soot particles generated as by-product of combustion under certain conditions. This conclusion was drawn based on both experimental and simulation results. Technical strategies to separate, reduce or remove the burst signal are proposed.
Coupled CFD-ANN Procedure for Extending Heat Transfer Correlations Out of Their Range of Validity
Authors: Viano Andrea , Ottino Gabriele , Ratto Luca , Spataro Giuseppe
Published: August 2013

The heat transfer coefficient and pressure losses are among the main parameters to be evaluated in gas turbine cooling network design. Due to the complexity of these estimates, correlation-based computations are typically used as a result of time-consuming and expensive experimental activities. One of the main problems that the industry has to face is that these correlations, based on non-dimensional experimental data, produce reliable results in a range of validity typically different from that encountered in gas turbine applications.

This paper will present preliminary results of an innovative procedure based on CFD analyses and Artificial Neural Networks, able to extend correlation predictions out of their range of validity, without any additional experimental data. Well-known test cases were replicated by building corresponding CAD geometries which were discretized by means of appropriate meshes, resulting from grid-independence studies. CFD analyses, based on the RANS approach, were performed to overlay the computations of the Nusselt number obtained from experimental activities. A preliminary comparison among turbulence models was carried out to find one leading to a good agreement with the experimental data. Then, an optimization method, based on Evolutionary Algorithms, was applied to the CFD analyses in order to find the best set of constant values for the chosen turbulence model, leading to the most accurate prediction of the experimental dataset. The resulting ad hoc CFD model was adopted in order to analyse test case configurations characterized by parameters within and external to the correlation validity field, building a sufficiently wide feeding database. A feed-forward multi-layer neural network was selected among network architectures typically used in engineering applications for prediction analyses. ANNs were chosen because they enable the solution of these complex nonlinear problems by using simple computational operations. The selected Artificial Neural Network was trained by a back-propagation procedure on the CFD results regarding Nusselt number. The validation of the resulting ANN was performed comparing its outputs with experimental data external to the correlation range of validity, which had not been used in the training session. Good agreement has been found. Results are presented and discussed.
High Temperature Film Cooling Test Facility and Preliminary Test Results
Authors: Straub D. L. , Sidwell T. G. , Casleton K. H. , Alvin M. A. , Chien S. , Chyu M. K.
Published: August 2013

This paper describes a new high temperature test facility developed through a collaborative effort between the University of Pittsburgh and the Department of Energy’s National Energy Technology Laboratory (NETL). The scope of this paper will include a description of this experimental test facility and a discussion of some test results collected from a flat plate (Haynes 230) using a single row of fan-shaped film cooling holes. This test specimen has been tested at two different pressures (i.e., 1.3 and 3 bar). The hot gas path flow velocity (i.e., 60 m/s) and the hot gas temperature (i.e., 1300 K) have been maintained as a constant for these tests. At each of these test conditions, five different film cooling blowing ratio conditions have been evaluated, including a condition with no film cooling. The overall cooling effectiveness and the reduction in heat flux for a point near the center of the test sample are reported and discussed.
Optimization of Film Cooling Holes on the Suction Surface of a High Pressure Turbine Blade
Authors: El Ayoubi Carole , Ghaly Wahid , Hassan Ibrahim
Published: August 2013

This paper aims to optimize film coolant flow parameters on the suction surface of a high-pressure gas turbine blade in order to obtain an optimum compromise between a high film cooling effectiveness and a low aerodynamic loss. An optimization algorithm coupled with three-dimensional Reynolds-averaged Navier Stokes (RANS) analysis is used to determine the optimum film cooling configuration. The VKI blade with two staggered rows of axially oriented, conically flared, film cooling holes on its suction surface is considered. Two design variables are selected; the coolant to mainstream temperature ratio and total pressure ratio. The effect of varying these coolant flow parameters on the film cooling effectiveness and the aerodynamic loss is analyzed using an optimization method and three dimensional steady CFD simulations. The optimization process involves a genetic algorithm and a response surface approximation of the artificial neural network type to provide low-fidelity predictions of the objective function. The CFD simulations are performed using the commercial software CFX. The numerical predictions of the aerodynamics and wall heat transfer are validated against experimental data. The optimization objective consists of maximizing the spatially averaged film cooling effectiveness and minimizing the aerodynamic penalty produced by film cooling. The results of this optimization are reported in terms of the aerodynamic loss and adiabatic cooling effectiveness.
Development and Validation of an Object-Oriented Code Implementing an Enhanced Radiative Joined MBL-Zonal Method Technique
Authors: Ratto Luca , Ottino Gabriele , Maritano Massimiliano
Published: August 2013

Gas turbines are the most widely employed high power prime movers for energy production and propulsion; their success is based on high power density, high reliability and low pollutant emissions. Due to the increasing performance request of modern gas turbines, combustion chambers and, more in general, turbine components are subjected to increasingly high thermal loads, due to both convection and radiation between solid walls and internal fluid. Computational Fluid Dynamics (CFD) tools are typically employed to reproduce these phenomena: commercial codes provide tools for both the heat transfer methods, but the radiation analysis sometimes could represent a great increase in the computational load; for this reason, it is a widespread industrial practice to avoid direct simulation of radiative phenomena during simulations, confining it during the post-processing activity. A typical industrial approach relies on the so-called Zonal Method, which guarantees a good compromise between accuracy of results and computational load. In a previous work, an innovative method for radiative thermal load evaluation has been presented by the authors, which is based on a joined Zonal Method-Mean Beam Length (MBL) approach: it enables a great reduction in time consumption by means of an appropriate Artificial Neural Network, but its usage is limited to hexahedral structured grids, which reduces its application to relatively simple geometries. In this paper, the method previously mentioned has been extended to unstructured tetrahedral grids. The procedure developed has been implemented in an object-oriented code by means of an open-source library: great advantages have been obtained both in the implementation, which results to be simpler, making any future modifications faster and intuitive, and in the application field, being extended to almost any kind of geometry. The code has been validated on literature test cases providing a good agreement between numerical and experimental results. Moreover, an industrial application has been described: it concerns the evaluation of the radiative heat transfer on the shells of an industrial gas turbine combustion chamber. Results are presented and discussed.
Numerical Investigation of Heat Transfer and Cooling Effectiveness Within a LPT-Vane Cascade and its Comparison to Experimental Results
Authors: Beuermann Annette , Pahs Andreas , Rochhausen Stefan
Published: August 2013

Gaps between stationary and rotating parts in turbines have to be fed with cooling air to keep metal temperatures below material limits. Reducing the coolant mass flow and analysing its impact on the flow field concerning aerodynamic and thermal data were the objectives of experiments, performed within the European research project AITEB.

As part of this project, measurements of cooling effectiveness and heat transfer on the endwall of a low pressure turbine nozzle guide vane were performed at a low speed cascade wind tunnel at DLR Göttingen.

Higher cooling mass flow rates increase secondary flows and subsequently heat transfer whilst metal temperatures are reduced due to larger coverage with coolant. It was also shown that heat transfer varies significantly with different flow angles.

According to the experimentally investigated flow fields numerical studies were performed using the DLR code TRACE, a RANS-Solver for turbomachinery flows. TRACE simulations were done using the Wilcox k-ω turbulence modelling. The boundary conditions were taken from the experimental setup.

In this paper the numerical data was analysed and compared with the experimental results regarding thermodynamics. The simulations confirmed a high influence of the flow angle. Within the flow regime affected by the injected coolant a good agreement between the numerical heat transfer results and the experimental data was observed. The qualitative and quantitative values were met after finding the optimum calculation parameters. Only in the region downstream of the throat area a different behaviour became obvious. Concerning film-cooling effectiveness quantitative differences between simulation and experiment were found whilst qualitative good agreement was observed.
Full Thermal Experimental Assessment of a Dendritic Turbine Vane Cooling Scheme
Authors: Luque S. , Batstone J. , Gillespie D. R. H. , Povey T. , Romero E.
Published: August 2013

A full thermal experimental assessment of a novel dendritic cooling scheme for high-pressure turbine vanes has been conducted and is presented in this paper, including comparisons to the conventional cooling arrangement for these components. The dendritic cooling system consists of cooling holes with multiple internal branches which enhance internal heat transfer and reduce the blowing ratio at hole exit. Three sets of measurements are presented, which describe, first, the local internal heat transfer coefficient of these structures, and, secondly, the cooling flow capacity requirements and overall cooling effectiveness of a highly engine-representative dendritic geometry.

Full-coverage surface maps of overall cooling effectiveness were acquired for both dendritic and baseline vanes in the Annular Sector Heat Transfer Facility, where scaled near-engine conditions of Mach number, Reynolds number, inlet turbulence intensity and coolant-to-mainstream pressure ratio (or momentum flux ratio) are achieved. Engine hardware was used, with laser-sintered metal counterparts for the novel cooling geometry (their detailed configuration, design, and manufacture are discussed). The dendritic system will be shown to offer improved overall cooling effectiveness at a reduced cooling mass flow rate due to a more uniform film cooling effectiveness, a decreased tendency for films to lift off in regions of low external cross flow, improved through-wall heat transfer and internal cooling efficiency, increased internal wetted surface area of the cooling holes, and the enhanced turbulence induced in them.
Coupled Simulation of the Secondary Air Flow, Heat Transfer, and Structural Deflection of a Gas Turbine Engine
Authors: Tondello Guilherme , Boruszewski Wolodymir , Mengele Fernando , Assato Marcelo , Shimizu Silvio , Ziegler Shayne
Published: August 2013

In secondary air flow in gas turbines, labyrinth seals are used to control the flow to and from each cavity and to the rotor blades for cooling purposes.

Those components and the final flow rate are very sensitive to gap clearance and displacement due to structural and thermal loads during operation, therefore designing those seals and knowing the resultant flow rates in each part of the circuit during the design phase is not an easy task, and tuning those gap values may bring significant increase in turbine efficiency.

This paper describes the application of coupled commercial codes for secondary air flow and structural simulation for better evaluating temperature profiles and labyrinth seal behavior during operation.

Flowmaster V7 was used for building a one dimensional model of the complete secondary air flow path including swirl effects and heat transfer phenomena, and ANSYS was used for building a structural model, taking into account both rotational and thermal loads.

The labyrinth seals clearances, and thermal interactions between solid and fluid were coupled bi-directionally between the two simulation software.

This simulation focused in the system, including the effects of each region, passage, seal and cavity in the calculations.

The turbine model simulated was a VSE’s gas turbine under development, having a nominal rotation of 22600 rpm.

This paper presents the numerical characteristics of each model, the details about the 1D fluid and 3D structural coupling, and the results obtained.
Comparison of Harmonic and Time-Marching Unsteady CFD Solutions With Measurements for a Single Stage High-Pressure Turbine
Authors: Green Brian R. , Mathison Randall M. , Dunn Michael G.
Published: August 2013

The unsteady aerodynamics of a single-stage high-pressure turbine has been the subject of a study involving detailed measurements and computations. Data and predictions for this experiment have been presented previously, but the current study compares predictions obtained using the nonlinear harmonic simulation method to results obtained using a time-marching simulation with phase-lag boundary conditions.

The experimental configuration consisted of a single-stage high-pressure turbine (HPT) and the adjacent, downstream, low-pressure turbine nozzle row (LPV) with an aerodynamic design that is typical to that of a commercial high-pressure ratio HPT and LPV. The flow path geometry was equivalent to engine hardware, and operated at the proper design-corrected conditions to match cruise conditions. The high-pressure vane and blade were un-cooled for these comparisons. All three blade-rows are instrumented with flush-mounted, high frequency response pressure transducers on the airfoil surfaces, and the inner and outer flow path surfaces, which include the rotating blade platform and the stationary shroud above the rotating blade.

Predictions of the time-dependent flow field for the turbine flow path were obtained using a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code. Using a two blade row computational model of the turbine flow path, the unsteady surface pressure for the high-pressure vane and rotor was calculated using both unsteady methods.

The two sets of predictions are then compared to the measurements looking at both time-averaged and time-accurate results, which show good correlation between the two methods and the measurements. This paper concentrates on the similarities and differences between the two unsteady methods, and how the predictions compare with the measurements since the faster harmonic solution could allow turbomachinery designers to incorporate unsteady calculations in the design process without sacrificing accuracy when compared to the phase-lag method.
Film Cooling With a Thermal Barrier Coating: Round Holes, Craters and Trenches
Authors: Davidson F. Todd , Kistenmacher David A. , Bogard David G.
Published: August 2013

Little work has been done to understand the interconnected nature of film cooling and thermal barrier coatings (TBC’s) on protecting high temperature turbine components. With increasing demands for improved engine performance it is vital that a greater understanding of the thermal behavior of turbine components is achieved. The purpose of this study was to investigate how various film cooling geometries affect the cooling performance of a thermally conducting turbine vane with a TBC. The vane model used in this study was designed to match the thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the thermal conductivity of the vane wall. This allowed for the measurement of temperatures at the interface of the TBC and vane wall which, when non-dimensionalized, are representative of the temperatures present for actual engine vanes. This study found that the addition of TBC on the surface of an internally cooled vane produced a near constant cooling performance despite significant changes in the blowing ratio. The craters, trench and modified trench of this study were found to provide much better film cooling coverage than round holes; however, the improved film cooling coverage led to only slight improvements in temperature at the interface of the TBC and vane wall. These results suggest that there is minimal advantage in using more complicated cooling configurations, particularly since they may be more susceptible to TBC spallation. However, the improved film coverage from the trench and crater designs may increase the life of the TBC which would be greatly beneficial to the long-term thermal protection of the vane.
Flow and Heat Transfer in a Jet-Impingement Configuration With No Cross Flows About Impinging Jets
Authors: Lee C.-S. , Shih T. I-P. , Bryden K. M. , Ames R. , Dennis R. A.
Published: August 2013

Computations were performed to study the flow and heat transfer in a jet-impingement configuration in which there is no cross flow about the impinging cooling jets. The configuration consists of two sets of staggered arrays of holes with one array of holes for jets to impinge and cool a target wall with or without strategically positioned pin fins and a second array positioned midway relative to the first array of holes for the impinging jets to exit the configuration. For this configuration, the following parameter were investigated: distance between the jet-hole exit and the target surface to be cooled (H/d = 0.5, 1, 4), spacing between jets (S/d = 2, 4), and pin-fin height (Hp/d = 0, 1, 2) on the target surface, where d is the diameter of the holes in the arrays. Also, the jet-impingement velocity was varied to study a range Reynolds numbers based on the hole diameter d and the mean velocity of the jet in the hole (Red = 20,000, 40,000, and 60,000). For all cases studied, the temperature of the coolant air is 673 K; the wall to be cooled is maintained at 1,273 K; and the static pressure at the exit of the jet-impingement array is maintained at 25 bars. This computational study is based on steady RANS – compressible Navier-Stokes with the shear-stress transport model for turbulence where integration is to the wall (i.e., wall functions were not used) and temperature-dependent properties are accounted for.
An Investigation of Applicability of Transporting Water Mist for Cooling Turbine Vanes
Authors: Ragab Reda , Wang Ting
Published: August 2013

This paper presents a numerical study to investigate the feasibility of transporting mist through the internal cooling channel in high-pressure turbine vanes for film cooling over the vane’s surface. The idea of using mist film cooling to enhance conventional air cooling has been proven to be a feasible technique in the laboratory conditions and by computational simulations. However, there is a challenge to this technique to prove that the water mist can survive in the very hot environment inside the gas turbine casings and internal air passages and be delivered to the film injection holes. Both a zero-dimensional mist evaporation analytical model and 3-D computational fluid dynamic (CFD) scheme are employed for analysis. In the CFD simulation, the Lagrangian /Eulerian method is used along with the discrete phase model (DPM) to track the evaporation process of water droplets. The high-pressure water mist is injected into the stream of cooling air extracted from the compressor through the outer gas turbine casing near the vane before it reaches the vane internal cooling cavity. Using the mist equivalent of 10% of the cooling air mass flow rate, the results show that, when the liquid droplets are atomized to 30 μm in diameter initially, the droplets can survive inside the internal cooling passages and be delivered to the film cooling injection hole location with droplets of 20 μm in diameter; and alternatively, an initially 20 μm droplet can be delivered at 12μm in diameter, which is sufficiently large for completing the required external film cooling task.
Two Dimensions of Value: Dopamine Neurons Represent Reward But Not Aversiveness
Authors: Fiorillo Christopher D.
Published: August 2013

Coding Reward Versus Punishment

Reinforcement learning is driven by reward prediction error, and a very influential theory has proposed that dopamine neurons provide this signal to teach value to the brain. Although this is called a reward prediction error, it has been assumed to also represent aversiveness. Thus, it was thought that the dopamine signal could be sufficient for learning total value.
Fiorillo
(p.
546
) found that dopamine alone was not sufficient to encode value, implying that there must be an analogous signal for aversiveness.
Liquid-Mediated Dense Integration of Graphene Materials for Compact Capacitive Energy Storage
Authors: Yang Xiaowei , Cheng Chi , Wang Yufei , Qiu Ling , Li Dan
Published: August 2013

Keeping Electrolytes in Porous Electrodes

Electrochemical capacitors (ECs) can rapidly charge and discharge, but generally store less energy per unit volume than batteries. One approach for improving on the EC electrodes made from porous carbon materials is to use materials such as chemically converted graphene (CCG, or reduced graphene oxide), in which intrinsic corrugation of the sheets should maintain high surface areas. In many cases, however, these materials do not pack into compact electrodes, and any ECs containing them have low energy densities.

Yang
et al.

(p.
534
) now show that capillary compression of gels of CCG containing both a volatile and nonvolatile electrolyte produced electrodes with a high packing density. The intersheet spacing creates a continuous ion network and leads to high energy densities in prototype ECs.
Climate Change Impacts on Global Food Security
Authors: Wheeler Tim , von Braun Joachim
Published: August 2013

Climate change could potentially interrupt progress toward a world without hunger. A robust and coherent global pattern is discernible of the impacts of climate change on crop productivity that could have consequences for food availability. The stability of whole food systems may be at risk under climate change because of short-term variability in supply. However, the potential impact is less clear at regional scales, but it is likely that climate variability and change will exacerbate food insecurity in areas currently vulnerable to hunger and undernutrition. Likewise, it can be anticipated that food access and utilization will be affected indirectly via collateral effects on household and individual incomes, and food utilization could be impaired by loss of access to drinking water and damage to health. The evidence supports the need for considerable investment in adaptation and mitigation actions toward a “climate-smart food system” that is more resilient to climate change influences on food security.
Why Male Mammals Are Monogamous
Authors: Kappeler Peter M.
Published: August 2013

Social monogamy evolved many times across mammals as a male mating strategy in species where females are widely spaced for ecological reasons.

[Also see Research Article by
Lukas and Clutton-Brock
]
Is Embracing Change Our Best Bet?
Novel Ecosystems
Intervening in the New Ecological World Order

by Richard J. Hobbs, Eric S. Higgs, and Carol M. Hall, Eds.

Wiley-Blackwell, Oxford, 2013. 380 pp. $79.95, £45, €53.90. ISBN 9781118354223.
Authors: Mateos David Moreno
Published: August 2013

Offering a range of perspectives on novel ecosystems, the contributors argue we must adapt ecosystem management in light of invasive species and global climate changes.
Feed Your T
regs
More Fiber
Authors: Bollrath Julia , Powrie Fiona
Published: August 2013

Microbes that metabolize dietary fiber can generate key fatty acids that enforce regulatory T cells in the gut.

[Also see Report by

Smith
et al.

]
Climate Change Impacts
Authors: McNutt Marcia
Published: August 2013

Anticipating the future under the influence of climate change is one of the most important challenges of our time, and the topic of the special section in this issue of
Science
(see p. 472). The natural systems that provide oxygen, clean water, food, storm and erosion protection, natural products, and the potential for future resources, such as new genetic stocks for cultivation, must be protected, not just because it is part of good stewardship but also so that they can take care of us. But even the first step of modeling the effects of greenhouse gas sources and sinks on future temperatures requires input from atmospheric scientists, oceanographers, ecologists, economists, policy analysts, and others. The problem is even more difficult because the very factors that influence temperature changes, such as ocean circulation and terrestrial ecosystem responses, will themselves be altered as the climate changes.With so many potential climate-sensitive factors to consider, scientists need ways to narrow down the range of possible environmental outcomes so that they know what specific problems to tackle.
Is High-Tech View of HIV Too Good to Be True?
Authors: Cohen Jon
Published: August 2013

Tumult erupts over publication of viral structure that strains credulity.
Study Links Climate Change and Violence, Battle Ensues
Authors: Bohannon John
Published: August 2013

Some social scientists say climate change could lead to escalating violence, and a new study is trying to quantify this increase.
Corruption and Research Fraud Send Big Chill Through Big Pharma in China
Authors: Hvistendahl Mara
Published: August 2013

The corruption scandal at GlaxoSmithKline involving sales tactics in China could have significant fallout for a booming pharmaceutical R&D base.
Advancing Seasons in China
Authors: Pennisi Elizabeth
Published: August 2013

Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.
Effect of HIV and Chlamydia Infection on Rectal Inflammation and Cytokine Concentrations in Men Who Have Sex with Men
Authors: Heiligenberg Marlies , Lutter René , Pajkrt Dasja , Adams Karin , De Vries Henry , Heijman Titia , Schim van der Loeff Maarten F. , Geerlings Suzanne
Published: August 2013

AsymptomaticChlamydia trachomatisinfections are common in HIV-infected men who have sex with men (MSM). AlthoughC. trachomatiscombined with HIV would be likely to enhance inflammation, the asymptomatic course suggests otherwise. We assessed local inflammation, mucosal damage, and cytokine concentrations in rectal mucosal fluid samples from patients with HIV (with or without the use of combination antiretroviral therapy [cART]) and with or without the presence of rectalC. trachomatis. Rectal swabs from 79 MSM (with and withoutC. trachomatis, HIV, and cART use) who reported a history of receptive anal sex were analyzed for neutrophil activation (measured by myeloperoxidase [MPO]), mucosal leakage (measured by albumin and alpha-2-macroglobulin), and proinflammatory and anti-inflammatory cytokines.C. trachomatisinfection, HIV infection, and cART use in MSM had no differential effects on rectal neutrophilic inflammation and mucosal damage. Interleukin 8 (IL-8) was found to correlate with MPO, and MPO correlated with markers of mucosal damage. In HIV-negative participants, men withC. trachomatisinfection had lower concentrations of monocyte chemotactic protein 1 (MCP-1), IL-1α, and IL-1 receptor antagonist (IL-1RA) than men without rectalC. trachomatisinfection (P= 0.005, 0.007, and 0.07, respectively). We found no difference in anal cytokine concentrations in HIV-infected participants in relation to the presence ofC. trachomatisinfection or cART use. In participants with rectalC. trachomatisinfection, those who were HIV negative had lower median concentrations of IL-8 and IL-1α than those with HIV (P= 0.05 and 0.06, respectively). The slope of the regression line between MPO and IL-8 was reduced in participants with rectalC. trachomatisinfection.C. trachomatisdampens cytokine concentrations but not in HIV-infected patients. The extent of mucosal damage was comparable in all patient groups. The apparent reduced neutrophil response to IL-8 in HIV-infected patients withC. trachomatisinfection is in accordance with its asymptomatic course.
Stability of Cervical Specimens in SurePath Medium for Human Papillomavirus Testing with the Roche cobas 4800 Assay
Authors: Gilbert Laura , Oates Elizabeth , Ratnam Samuel
Published: August 2013

The stability of cervical specimens in SurePath preservative fluid for human papillomavirus (HPV) testing with Roche cobas 4800 was determined using a panel of 308 pooled specimens from a colposcopy referral population. The SurePath specimens appeared to be stable for up to 10 weeks at ambient temperature for HPV testing with cobas 4800.
Dystonin/BPAG1 Promotes Plus-End-Directed Transport of Herpes Simplex Virus 1 Capsids on Microtubules during Entry
Authors: McElwee Marion , Beilstein Frauke , Labetoulle Marc , Rixon Frazer J. , Pasdeloup David
Published: August 2013

During infection by herpes simplex virus 1 (HSV-1), the viral capsid is transported around the cytoplasm along the microtubule (MT) network. Although molecular motors have been implicated in this process, the composition of the molecular machinery required for efficient directional transport is unknown. We previously showed that dystonin (BPAG1) is recruited to HSV-1 capsids by the capsid-bound tegument protein pUL37 to promote efficient cytoplasmic transport of capsids during egress. Dystonin is a cytoskeleton cross-linker which localizes at MT plus ends and has roles in retrograde and anterograde transport in neurons. In this study, we investigated the role of dystonin during the entry stages of HSV-1 infection. Because of the way in which the MT network is organized, capsids are required to change their direction of motion along the MTs as they travel from the point of entry to the nucleus, where replication takes place. Thus, capsids first travel to the centrosome (the principal microtubule organizing center) by minus-end-directed transport and then switch polarity and travel to the nucleus by plus-end-directed transport. We observed that transport of capsids toward the centrosome was slowed, but not blocked, by dystonin depletion. However, transport of capsids away from the centrosome was significantly impaired, causing them to accumulate in the vicinity of the centrosome and reducing the numbers reaching the nucleus. We conclude that, during entry of HSV-1, dystonin has a specific role in plus-ended transport of capsids from the centrosome to the nucleus.
Endometrial stromal sarcoma of the uterus presenting as pulmonary metastasis
Authors: Binesh Fariba , Taghipour Zahir Shokouh , Akhavan Ali , Roshan Bovanlu Taghi
Published: August 2013

Endometrial stromal sarcoma (ESS) is a rare uterine sarcoma. Compared with other uterine malignancies, it occurs at an earlier age (42–58 years) and about 10–25% of the patients are premenopausal. The tumours have an indolent growth, with a tendency for late recurrence. Metastases are rarely detected before the diagnosis of the primary lesion. We report a case of ESS with pulmonary metastasis as a prodromal manifestation.
CAPS: a rare acute abdomen
Authors: Smith John-Paul , Woodward Mark , Tunstall Oliver , Ramanan Athimalaipet
Published: August 2013

An 11-year-old girl presented to the hospital with vomiting, left upper-quadrant pain and blood in the stool. An ultrasound scan showed no blood flow in the coeliac axis or the splenic artery. A contrast-enhanced CT scan then demonstrated no flow beyond the coeliac axis origin, a large clot in the distal superior mesenteric artery (SMA), a large splenic infarct and bilateral renal infarcts. Investigations revealed a positive lupus anticoagulant and she was given a presumptive diagnosis of catastrophic antiphospholipid syndrome (CAPS). She was anticoagulated and started on combination immunosuppressive therapy. Her surgical management was by SMA embolectomy, small bowel resection and proximal stoma formation. Stoma closure was performed at 3 months, and she was eventually established on full enteral feeds. Childhood CAPS is a rare condition with a very high mortality rate, and the successful outcome in this case reflects close multidisciplinary teamwork between medical and surgical specialties.
Solitary lumbar osteochondroma presenting with spinal cord compression
Authors: Natale Massimo , Rotondo Michele , D'Avanzo Raffaele , Scuotto Assunta
Published: August 2013

We report a case of a middle-aged woman with a solitary osteochondroma of the L2 right lamina with intraspinal extension and spinal cord compression. The case is unusual in terms of localisation and age at clinical presentation. In fact, spinal osteochondromas as solitary lesions—especially when affecting the lumbar segment—are rare tumours of a maturing adolescent skeleton, infrequently affecting the neurological structures, because most of the lesions grow out of the spinal canal. Although unusual, they should be considered in the differential diagnosis. Prompt and accurate radiological investigations are important in planning appropriate management. Surgical total excision is the best treatment modality to remove spinal cord and/or nerve root compression, and to avoid the risk of recurrence or malignant transformation.
Primary oral tuberculosis
Authors: Verma Sankalp , Mohan Ravi Prakash Sasankoti , Singh Udita , Agarwal Neha
Published: August 2013

Persistent oral ulcers and erosions can be the final common manifestation, sometimes clinically distinguishable, of a diverse spectrum of conditions ranging from traumatic lesions, infectious diseases, systemic and local immune-mediated lesions up to neoplasms. A case with oral tuberculosis and absence of any systemic manifestations is reported. The location and clinical presentation of the lesion is unusual and underlines the importance of considering tuberculosis in the differential diagnosis of oral lesions that affect the mucosa and the gingiva.
Primary orbital chronic granulomatous reaction to deep staphylococcal infection due to trauma in immunocompetent
Authors: Rao Lavanya G , Gonsalves Sarita R J , Pathan Atiya , Sinha Akansha
Published: August 2013

A 53-year-old man presented with a slow-growing mass in the right orbit and temporal area of 1 year duration following a road traffic accident. Examination revealed a nodular fungating mass involving the orbit, right temporal area with multiple discharging sinuses causing proptosis and restricted ocular motility. The patient denied light perception in the right eye. There was exposure keratopathy and optic atrophy. Imaging showed mass lesion of the orbit extending intracranially. Tissue biopsy and culture revealed a chronic granulomatous reaction due to deep infection with coagulase-positive staphylococci. The patient showed remarkable improvement to systemic antibiotics and anticonvulsants. Mortality is high in such cases due to intracranial extension if there is a delay in treatment. This case report summarises a rare aetiology and successful treatment of a case of chronic granulomatous reaction due to deep bacterial infection following trauma and is deemed rare as cases of primary orbital infection in immunocompetent have not been reported so far.
Nocardiapneumonia in an HIV-infected neonate presenting as acute necrotising pneumonia
Authors: Goussard Pierre , Gie Robert , Rabie Helena , Andronikou Savvas
Published: August 2013

We describe an expansile necrotising pneumonia caused byNorcardiain a HIV-infected 3-week-old baby. The radiological images and treatment ofNorcardiain immune deficient children are discussed.
Uterine torsion mimicking supine hypotension syndrome after regional anaesthesia
Authors: Arumugham Silja , Mathew Mariam , Deoskar Sonali , Sharma Jasvinder
Published: August 2013

A 40-year-old gravida 5 para2 +2 was admitted at 38 weeks +5 days of gestation for elective caesarean section in view of unstable lie. After spinal anaesthesia, when the patient was positioned supine for caesarean section, she developed acute onset breathlessness and dizziness. Blood pressure was unrecordable. She remained symptomatic with hypotension and bradycardia despite lateral tilt and intravenous atropine. On entering the peritoneal cavity, a congested uterus with torsion in a clockwise direction to almost 180° with the posterior wall facing anteriorly was noted. Immediate attempt to detort the uterus was successful. The patient immediately became symptomatically better and the uterine congestion resolved. Uterine incision was given in the anterior lower segment delivering a healthy baby. High index of suspicion and detorsion of the uterus avoided the inadvertent incision in the congested posterior uterine wall which could have resulted in massive postpartum haemorrhage.