Improving GPGPU Concurrency with Elastic Kernels

Each new generation of GPUs vastly increases the resources available to GPGPU programs. GPU programming models (like CUDA) were designed to scale to use these resources. However, we find that CUDA programs actually do not scale to utilize all available resources, with over 30% of resources going unused on average for programs of the Parboil2 suite that we used in our work. Current GPUs therefore allow concurrent execution of kernels to improve utilization. In this work, we study concurrent execution of GPU kernels using multiprogram workloads on current NVIDIA Fermi GPUs. On two-program workloads from the Parboil2 benchmark suite we find concurrent execution is often no better than serialized execution. We identify that the lack of control over resource allocation to kernels is a major serialization bottleneck. We propose transformations that convert CUDA kernels into elastic kernels which permit fine-grained control over their resource usage. We then propose several elastic-kernel aware concurrency policies that offer significantly better performance and concurrency compared to the current CUDA policy. We evaluate our proposals on real hardware using multiprogrammed workloads constructed from benchmarks in the Parboil 2 suite. On average, our proposals increase system throughput (STP) by 1.21x and improve the average normalized turnaround time (ANTT) by 3.73x for two-program workloads when compared to the current CUDA concurrency implementation.

Science of geoengineering

Carbon dioxide emissions from the burning of coal, oil, and gas are increasing atmospheric carbon dioxide concentrations. These increased concentrations cause additional energy to be retained in Earth's climate system, thus increasing Earth's temperature. Various methods have been proposed to prevent this temperature increase either by reflecting to space sunlight that would otherwise warm Earth or by removing carbon dioxide from the atmosphere. Such intentional alteration of planetary-scale processes has been termed geoengineering. The first category of geoengineering method, solar geoengineering (also known as solar radiation management, or SRM), raises novel global-scale governance and environmental issues. Some SRM approaches are thought to be low in cost, so the scale of SRM deployment will likely depend primarily on considerations of risk. The second category of geoengineering method, carbon dioxide removal (CDR), raises issues related primarily to scale, cost, effectiveness, and local environmental consequences. The scale of CDR deployment will likely depend primarily on cost.

Power-Controlled Reverse Channel Training in a Multiuser TDD-MIMO Spatial Multiplexing System With CSIR

This paper considers the design of a power-controlled reverse channel training (RCT) scheme for spatial multiplexing (SM)-based data transmission along the dominant modes of the channel in a time-division duplex (TDD) multiple-input and multiple-output (MIMO) system, when channel knowledge is available at the receiver. A channel-dependent power-controlled RCT scheme is proposed, using which the transmitter estimates the beamforming (BF) vectors required for the forward-link SM data transmission. Tight approximate expressions for 1) the mean square error (MSE) in the estimate of the BF vectors, and 2) a capacity lower bound (CLB) for an SM system, are derived and used to optimize the parameters of the training sequence. Moreover, an extension of the channel-dependent training scheme and the data rate analysis to a multiuser scenario with M user terminals is presented. For the single-mode BF system, a closed-form expression for an upper bound on the average sum data rate is derived, which is shown to scale as ((L-c - L-B,L- tau)/L-c) log logM asymptotically in M, where L-c and L-B,L- tau are the channel coherence time and training duration, respectively. The significant performance gain offered by the proposed training sequence over the conventional constant-power orthogonal RCT sequence is demonstrated using Monte Carlo simulations.

Macromolecular Crystallography in India in the Global Context

The most spectacular applications of crystallography are currently concerned with biological macromolecules like proteins and their assemblies. Macromolecular crystallography originated in England in the thirties of the last century, but definitive results began to appear only around 1960. Since then macromolecular crystallography has grown to become central to modern biology. India has a long tradition in crystallography starting with the work of K. Banerjee in the thirties. In addition to their contributions to crystallography, G.N. Ramachandran and his colleagues gave a head start to India in computational biology, molecular modeling and what we now call bioinformatics. However, attempts to initiate macromolecular crystallography in India started only in the seventies. The work took off the ground after the Department of Science and Technology handsomely supported the group at Indian Institute of Science, Bangalore in 1983. The Bangalore group was also recognized as a national nucleus for the development of the area in the country. Since then macromolecular crystallography, practiced in more than 30 institutions in the country, has grown to become an important component of scientific research in India. The articles in this issue provide a flavor of activities in the area in the country. The area is still in an expanding phase and is poised to scale greater heights.

Dynamics of the reaction between the free end of a tethered self-avoiding polymer and a flat penetrable surface: A renormalization group study

The average time tau(r) for one end of a long, self-avoiding polymer to interact for the first time with a flat penetrable surface to which it is attached at the other end is shown here to scale essentially as the square of the chain's contour length N. This result is obtained within the framework of the Wilemski-Fixman approximation to diffusion-limited reactions, in which the reaction time is expressed as a time correlation function of a ``sink'' term. In the present work, this sink-sink correlation function is calculated using perturbation expansions in the excluded volume and the polymer-surface interactions, with renormalization group methods being used to resum the expansion into a power law form. The quadratic dependence of tau(r) on N mirrors the behavior of the average time tau(c) of a free random walk to cyclize, but contrasts with the cyclization time of a free self-avoiding walk (SAW), for which tau(r) similar to N-2.2. A simulation study by Cheng and Makarov J. Phys. Chem. B 114, 3321 (2010)] of the chain-end reaction time of an SAW on a flat impenetrable surface leads to the same N-2.2 behavior, which is surprising given the reduced conformational space a tethered polymer has to explore in order to react. (C) 2014 AIP Publishing LLC.

Hydrological importance of sacred forest fragments in Central Western Ghats of India

Sacred groves are patches of forests of special spiritual significance to humans, offering also a diverse range of ecological and environmental services. We have attempted here to understand the local hydrological dynamics of a sacred forest, in terms of the benefits the village community derive, in central Western Ghats region of India. A comparative assessment has been made between two small watersheds in terms of their landscape structure (woody species composition) with soil water properties and availability of water in the respective downstream villages. The result shows that, sacred site with more primeval vegetation has close association with soil moisture in comparison to non-sacred site during dry spell of the year. The higher soil moisture ensures year long availability of water in the downstream village of the sacred site which facilitates farming of commercial crops with higher economic returns to the farmers, unlike the farmers in the other village where they face water crisis during the lean season. The study emphasizes the need for conservation endeavour on sacred groves highlighting its potential for water conservation at local and regional levels.

Investigation of critical state in melt processed YBa2Cu3O7-δ thick films

The magnetic moment of square planar melt processed YBa2Cu3O7-δ thick films is observed to scale with the cube of the sample width at 4.2 K, suggesting that current flow on the length scale of the film determines its magnetization at this temperature. A well-defined discontinuity in slope in the scaling data at a sample width corresponding to the average grain size (≈2 mm) implies the coexistence of distinct intra- and inter-grain critical current densities of 1.1 × 105Acm-2 and 0.4 × 105Acm-2 at 1 T and 4.2 K. The presence of a critical state in the films at 4.2T is confirmed by removing the central section from a specimen. The observed change in magnetic moment is in excellent agreement with theory for fields greater than ≈2 T. A critical state is not observed at 77 K which suggests that the grains are only weakly coupled at the higher temperature. © 1994.

La luz del intelecto agente en los principios de la razón práctica según San Alberto Magno

Resumen: La Antigone de Sófocles y el Corpus Hippocraticum delinean ya los rasgos propios del derecho natural. La ética de Aristóteles, luego, ofrece una primera noción explícita del derecho natural, que San Alberto Magno comenta en Super ethica. Sin embargo, en De inventione de Cicerón el teólogo alemán encuentra su definición de derecho natural: “lo que cierta fuerza innata introdujo”. En De bono V q. 1 San Alberto determina los alcances de esta definición y completa una presentación acabada de la noción de derecho natural. También advierte San Alberto que el hombre, con respecto a la ciencia del intelecto práctico, se encuentra doblemente en potencia. Primero, está en potencia de conocer los principios primeros de esta ciencia y, segundo, una vez conocidos éstos, se encuentra en potencia de inferir a partir de ellos las conclusiones de la ciencia práctica. Poseídas estas conclusiones, finalmente, el hombre está en potencia de aplicarlas en la acción práctica. Intrigado por el modo en que los primeros principios son conocidos, San Alberto advierte que el conocimiento de las nociones correspondientes a estos principios sólo accidentalmente debe ser atribuido al descubrimiento o determinación de los nombres con los que llamamos a estos principios. En verdad, es necesaria la intervención de la luz del intelecto agente para llevar al acto el conocimiento de los principios. En este punto el discurso de San Alberto retorna a la definición ciceroniana: aquella fuerza innata que introduce el derecho natural no es otra que la luz del intelecto agente.

El Matadero de Esteban Echeverría, o la inauguración de los mataderos

Resumen: En el presente texto retomamos y reconocemos el carácter de ‘texto fundante’ que El Matadero de Esteban Echeverría tiene en nuestra cultura argentina. Analizamos lo enraizado del texto conectándolo hacia atrás, con los orígenes de la gauchesca, y hacia adelante, con su culminación y con sus proyecciones, incluso en diversas disciplinas. Luego podemos centrarnos en el tema de la violencia como recurrente no solo literario, y precisar el sentido en que la tomamos. Sostenemos que la violencia de El Matadero ya estaba presente, de manera velada, en otras obras de Echeverría; no tanto por su tematización, sino porque figurativiza, de manera muy acorde con la ideología románticas, razón y corazón, considerado éste no como exclusiva sede de sentimientos, sino como víscera, y de allí sus equivalentes, como el estómago y el matambre. Esta parte visceral no accede a mayor formulación, porque no entra en el programa de la estética en boga. Desde este punto de vista, releo las quejas debidas al sufrimiento del corazón, y entiendo el llanto y el descontento de otro modo. Hay lamento porque nada, al menos en el terreno literario, brinda salida a ese fondo vivo, no esquemático y que le resulta abyecto, porque encierra un modo y un contenido que no puede reconocer como propios. Asociado con esta cara puesta en sombra, inopinadamente, El matadero vuelve a ser texto fundante, pero de otra parte de la literatura argentina: de lo marginal, que no puede sumarse a proyectos, y que muy pocos dicen.

Unloading characteristics of anti-plane shear crack in softening materials

The local characteristics of the anti-plane shear stress and strain field are determined for a material where the stress increases linearly with strain up to a limit and then softens nonlinearly. Two unloading models are considered such that the unloading path always returns to the origin while the other assumes the unloading modulus to be that of the initial shear modulus. As the applied shear increases, an unloading zone is found to prevail between a zone in which the material softens and another zone in which the material is linear-elastic even though the crack does not propagate. The divisions of these zones are displayed graphically.

Ceilings and Floors? Gender Wage Gaps by Education in Spain

Revised: 2006-11.-- Published as an article in: Journal of Population Economics, 2007, vol. 21 issue 3, pp. 751-776.

More on Identification on Detailed Wage Decompositions

Revised: 2006-05.-- Published as an article in: The Review of Economics and Statistics, 2004, vol. 86, issue 4, pp. 1034-1036.

Wage differentials between Permanent and Temporal Contracts: Further Evidence

The main objective of this paper is to estimate wage differentials between permanent and temporal workers for different qualification levels and decompose such differentials to see which factors contribute more to explain them. The data we use is the "Encuesta de Estructura Salarial", a survey carried out in 1995 in all countries of the European Union, which contains very detailed information on wages and other characteristics for about 180.000 workers. The empirical results indicate that (a) the wage gap between permanent and temporal workers increases with qualification and it is smaller for females than for males, (b) when decomposing average wage differentials for each qualification level, we observe that the vast majority of such differential is explainedby differences in characteristics, and in particular by differences in tenure and occupation. With respect to differences in returns, our results indicate that the returns to tenure are higher for temporal workres relative to permanent workers for both males and females and for every qualification level. Returns to occupation are higher for permanent than for temporal workers, and the differenceis particularly high for females.

Dynamics and scaling of self-excited passive vortex generators for underwater propulsion

A series of experiments was conducted on the use of a device to passively generate vortex rings, henceforth a passive vortex generator (PVG). The device is intended as a means of propulsion for underwater vehicles, as the use of vortex rings has been shown to decrease the fuel consumption of a vehicle by up to 40% Ruiz (2010).

The PVG was constructed out of a collapsible tube encased in a rigid, airtight box. By adjusting the pressure within the airtight box while fluid was flowing through the tube, it was possible to create a pulsed jet with vortex rings via self-excited oscillations of the collapsible tube.

A study of PVG integration into an existing autonomous underwater vehicle (AUV) system was conducted. A small AUV was used to retrofit a PVG with limited alterations to the original vehicle. The PVG-integrated AUV was used for self-propelled testing to measure the hydrodynamic (Froude) efficiency of the system. The results show that the PVG-integrated AUV had a 22% increase in the Froude efficiency using a pulsed jet over a steady jet. The maximum increase in the Froude efficiency was realized when the formation time of the pulsed jet, a nondimensional time to characterize vortex ring formation, was coincident with vortex ring pinch-off. This is consistent with previous studies that indicate that the maximization of efficiency for a pulsed jet vehicle is realized when the formation of vortex rings maximizes the vortex ring energy and size.

The other study was a parameter study of the physical dimensions of a PVG. This study was conducted to determine the effect of the tube diameter and length on the oscillation characteristics such as the frequency. By changing the tube diameter and length by factors of 3, the frequency of self-excited oscillations was found to scale as f~D_0^{-1/2} L_0^0, where D_0 is the tube diameter and L_0 the tube length. The mechanism of operation is suggested to rely on traveling waves between the tube throat and the end of the tube. A model based on this mechanism yields oscillation frequencies that are within the range observed by the experiment.

Decarbonising urban transportation

18 p.