Domain-Specific Acceleration and Auto-Parallelization of Legacy Scientific Code in FORTRAN 77 using Source-to-Source Compilation

Massively parallel accelerators such as GPGPUs, manycores and FPGAs represent a powerful and affordable tool for scientists who look to speed up simulations of complex systems. However, porting code to such devices requires a detailed understanding of heterogeneous programming tools and effective strategies for parallelization. In this paper we present a source to source compilation approach with whole-program analysis to automatically transform single-threaded FORTRAN 77 legacy code into OpenCL-accelerated programs with parallelized kernels. The main contributions of our work are: (1) whole-source refactoring to allow any subroutine in the code to be offloaded to an accelerator. (2) Minimization of the data transfer between the host and the accelerator by eliminating redundant transfers. (3) Pragmatic auto-parallelization of the code to be offloaded to the accelerator by identification of parallelizable maps and reductions. We have validated the code transformation performance of the compiler on the NIST FORTRAN 78 test suite and several real-world codes: the Large Eddy Simulator for Urban Flows, a high-resolution turbulent flow model; the shallow water component of the ocean model Gmodel; the Linear Baroclinic Model, an atmospheric climate model and Flexpart-WRF, a particle dispersion simulator. The automatic parallelization component has been tested on as 2-D Shallow Water model (2DSW) and on the Large Eddy Simulator for Urban Flows (UFLES) and produces a complete OpenCL-enabled code base. The fully OpenCL-accelerated versions of the 2DSW and the UFLES are resp. 9x and 20x faster on GPU than the original code on CPU, in both cases this is the same performance as manually ported code.Comment: 12 pages, 5 figures, submitted to "Computers and Fluids" as full paper from ParCFD conference entr

Re-estimation of argon isotope ratios leading to a revised estimate of the Boltzmann constant

In 2013, NPL, SUERC and Cranfield University published an estimate for the Boltzmann constant [1] based on a measurement of the limiting low-pressure speed of sound in argon gas. Subsequently, an extensive investigation by Yang et al [2] revealed that there was likely to have been an error in the estimate of the molar mass of the argon used in the experiment. Responding to [2], de Podesta et al revised their estimate of the molar mass [3]. The shift in the estimated molar mass, and of the estimate of kB, was large: -2.7 parts in 106, nearly four times the original uncertainty estimate. The work described here was undertaken to understand the cause of this shift and our conclusion is that the original samples were probably contaminated with argon from atmospheric air.
 In this work we have repeated the measurement reported in [1] on the same gas sample that was examined in [2, 3]. However in this work we have used a different technique for sampling the gas that has allowed us to eliminate the possibility of contamination of the argon samples. We have repeated the sampling procedure three times, and examined samples on two mass spectrometers. This procedure confirms the isotopic ratio estimates of Yang et al [2] but with lower uncertainty, particularly in the relative abundance ratio R38:36.
 Our new estimate of the molar mass of the argon used in Isotherm 5 in [1] is 39.947 727(15) g mol-1 which differs by +0.50 parts in 106 from the estimate 39.947 707(28) g mol-1 made in [3]. This new estimate of the molar mass leads to a revised estimate of the Boltzmann constant of kB = 1.380 648 60 (97) × 10−23 J K−1 which differs from the 2014 CODATA value by +0.05 parts in 106.&#13

Systematic review of physical activity interventions assessing physical and mental health outcomes on patients with severe mental illness (SMI) within secure forensic settings

WHAT IS KNOWN ON THE SUBJECT? Individuals with a severe mental illness (SMI) are less physically active and have a lower life expectancy than the general population due to increased risks of cardiometabolic diseases (obesity, diabetes and respiratory diseases) and other health risks. Physical activity has been used as an adjunct therapy for individuals with SMI yielding improvements in cognitive functioning, quality of life and a reduction in psychiatric symptoms. Individuals with SMI residing within a secure forensic setting have reduced physical activity opportunities, possibly due to a number of factors including low motivation and restricted access to exercise facilities combined with a lack of knowledge and/or confidence in staff members to assist in physical activity programmes. WHAT THE PAPER ADDS TO EXISTING KNOWLEDGE? This review demonstrates that little is known around the effects of physical activity for people with SMI who reside in secure forensic settings, with little to no long‐term effects reported. Physical activity interventions have shown some positive results through decreasing weight and waist circumference as well as a reduction in negative symptom scores in an exercise group compared with the “no treatment” control group post‐intervention. WHAT ARE THE IMPLICATIONS FOR PRACTICE? Service users’ reluctance to engage in physical activity may be overcome by improving staff commitment, creating a motivational atmosphere and promoting service user decision making. ABSTRACT: INTRODUCTION: Participating in physical activity has many benefits, yet those with severe mental illness (SMI) living in forensic settings are less likely to be active, and more likely to experience ill‐health. The aim of this study was to systematically review the effectiveness of physical activity programmes on mental and physical health and specifically on reducing symptoms of SMI in forensic settings. METHOD: A systematic search of six databases was conducted, in addition to a grey literature search. Studies were included if they had participants with SMI; were based in a forensic setting; involved a physical activity programme and reported physical and mental health outcomes. RESULTS: A total of 112 participants were included in four studies. One study showed a significant improvement in negative symptom scores in the exercise group compared with a treatment as usual group. Two studies reported improvements in psychiatric symptoms with no significant difference between groups; however, statistically significant changes in weight and waist circumference were evident (p < .001). No adverse effects were reported. CONCLUSION: Only a small number of studies were included and of limited design and quality, with no follow‐up assessments; therefore, more research is needed to determine the true effects of physical activity for improving SMI symptoms in a forensic setting. This review highlights the need for further studies exploring the barriers and facilitators of physical activity in secure forensic settings. Studies are required that include a more thorough research design. Furthermore, interventions if designed with patients and caring staff in mind may lead to lowered psychiatric symptoms and increased physical health benefits for all in forensic settings