An efficient and portable SIMD algorithm for charge/current deposition in Particle-In-Cell codes

In current computer architectures, data movement (from die to network) is by far the most energy consuming part of an algorithm (10pJ/word on-die to 10,000pJ/word on the network). To increase memory locality at the hardware level and reduce energy consumption related to data movement, future exascale computers tend to use more and more cores on each compute nodes ("fat nodes") that will have a reduced clock speed to allow for efficient cooling. To compensate for frequency decrease, machine vendors are making use of long SIMD instruction registers that are able to process multiple data with one arithmetic operator in one clock cycle. SIMD register length is expected to double every four years. As a consequence, Particle-In-Cell (PIC) codes will have to achieve good vectorization to fully take advantage of these upcoming architectures. In this paper, we present a new algorithm that allows for efficient and portable SIMD vectorization of current/charge deposition routines that are, along with the field gathering routines, among the most time consuming parts of the PIC algorithm. Our new algorithm uses a particular data structure that takes into account memory alignement constraints and avoids gather/scatter instructions that can significantly affect vectorization performances on current CPUs. The new algorithm was successfully implemented in the 3D skeleton PIC code PICSAR and tested on Haswell Xeon processors (AVX2-256 bits wide data registers). Results show a factor of $\times 2$ to $\times 2.5$ speed-up in double precision for particle shape factor of order $1$ to $3$. The new algorithm can be applied as is on future KNL (Knights Landing) architectures that will include AVX-512 instruction sets with 512 bits register lengths (8 doubles/16 singles).Comment: 36 pages, 5 figure

Pre-Interventional Cardiac and ECG Changes in Acute Organophosphate Poisoning Cases Admitted to a Tertiary Hospital in India

Background: Cardiac complications are the less common fatal effect of acute organophosphate poisoning. This study was undertaken to analyze the pre-interventional cardiac and Electrocardiographic (ECG) changes in acute organophosphate poisoning cases.Materials and Methods: Clinical records of acute organophosphate poisoning patients of age less than 50 years admitted to KLE’s Dr. Prabhakar Kore Hospital, Belgaum, Karnataka, from 01-01-2010 to 31-12-2010 were analyzed. Cases of organophosphate poisonings referred from other hospitals, poisoning with multiple agents, patients with history of previous cardiac diseases and coexisting medical conditions were excluded from the study. Poisoning Severity Score was calculated as per International Programme on Chemical Safety and patients were grouped into 3 grades.Results: In this study, 50 cases of acute organophosphate poisoning (male - 32; female - 18) were analyzed. Sinus tachycardia was present in 45 patients (90%), hypertension in 13 (26%) and hypotension in 12 (24%). Prolonged corrected QT interval was observed in 14 patients (28%), elevated ST segment in 2 (4%), inverted T wave in 13 (26%) and conduction defects in 1 (2%). Among 14 patients with prolonged corrected QT interval, 12 were in grade III and 2 in grade II severity; and, among 13 patients who had inverted T wave, 2 were in grade I, 4 in grade II and 7 in grade III severity. Acidosis, as assessed by blood pH and HCO3, was observed in 22 patients (44%).Conclusion: Fatal cardiac complications do occur in acute organophosphate poisoning, which are overlooked at times as the most common complications expected are respiratory complications. Higher incidence of ECG changes in Grade III cases suggests that if the cardiac complications develop, the patient should be immediately transferred to an intensive cardiac care unit

Effect of Compaction Stresses on Performance of Back-to-Back Retaining Walls

Back-to-back reinforced soil retaining walls are commonly used for approach embankments of bridges and flyovers. Existing design guidelines (FHWA/BS/IS codes) do not provide a mechanistic approach to design back-to-back reinforced soil retaining walls. Lateral pressures on the facing and at end of reinforced zone are required for stability checks (both internal and external). During stage-wise construction of back-to-back walls, compaction stresses should be incorporated to obtain realistic lateral earth pressures on the walls. The present paper describes the effect of the compaction stresses on the lateral pressures in such reinforced soil retaining walls. The variation of lateral pressures at the end of reinforced zone along the depth of the wall is obtained from numerical modeling of back-to-back reinforced soil walls. A surcharge load of 30 kPa is applied at the end of the construction of the wall. It is observed that the effect of surcharge load is not significant after certain depth of the wall for lower spacing between walls to wall height ratios. A comparison on lateral pressures with and without compaction stresses for different distances between the ends of reinforcements of two walls is presented. Effect of connection of reinforcement is also studied

Analysis of Back-To-Back Reinforced Retaining Walls with Modular Block Facing

Back-to-back reinforced retaining walls are mostly used in approach embankments for bridges and flyovers. Guidelines on the design of such walls are limited. According to FHWA codal provisions, the distance between back-to-back walls is an important parameter in estimating the lateral earth pressures on these walls. For back-to-back walls of height ‘H’ with backfill angle of shearing resistance ‘’, two cases are given in the code: a) the walls are sufficiently far away with the distance between the facings of reinforcements extending from the two walls (D) is greater than H*tan(45o-ϕ/2), the walls are designed as independent walls, and b) the ends of the reinforcements for the two walls overlap by a distance more than 0.3*H, the active lateral earth pressure is taken as zero while performing the check for external stability. If the distance between the walls is intermediate between these two cases, the lateral earth pressures of the walls are linearly interpolated. However, there is no literature available to justify the above mentioned earth pressure distribution for back-to-back reinforced walls. The objective of this study is to obtain the effect of distance between the far ends of reinforcements normalized with the wall height (D/H) on the lateral pressures at the facing of the wall and at the end of reinforcement. In this study, charts are proposed showing the variation of lateral pressures and facing displacements with depth for D/H varying from 0.0 to 0.6 and for different reinforcement stiffness ranging from 500 kN/m to 50000 kN/m

GEMv2 : Multilingual NLG benchmarking in a single line of code

Evaluation in machine learning is usually informed by past choices, for example which datasets or metrics to use. This standardization enables the comparison on equal footing using leaderboards, but the evaluation choices become sub-optimal as better alternatives arise. This problem is especially pertinent in natural language generation which requires ever-improving suites of datasets, metrics, and human evaluation to make definitive claims. To make following best model evaluation practices easier, we introduce GEMv2. The new version of the Generation, Evaluation, and Metrics Benchmark introduces a modular infrastructure for dataset, model, and metric developers to benefit from each others work. GEMv2 supports 40 documented datasets in 51 languages. Models for all datasets can be evaluated online and our interactive data card creation and rendering tools make it easier to add new datasets to the living benchmark.Peer reviewe

GEMv2 : Multilingual NLG benchmarking in a single line of code

Evaluation in machine learning is usually informed by past choices, for example which datasets or metrics to use. This standardization enables the comparison on equal footing using leaderboards, but the evaluation choices become sub-optimal as better alternatives arise. This problem is especially pertinent in natural language generation which requires ever-improving suites of datasets, metrics, and human evaluation to make definitive claims. To make following best model evaluation practices easier, we introduce GEMv2. The new version of the Generation, Evaluation, and Metrics Benchmark introduces a modular infrastructure for dataset, model, and metric developers to benefit from each others work. GEMv2 supports 40 documented datasets in 51 languages. Models for all datasets can be evaluated online and our interactive data card creation and rendering tools make it easier to add new datasets to the living benchmark.Peer reviewe

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery