Formalization of Phase Ordering

Phasers pose an interesting synchronization mechanism that generalizes many collective synchronization patterns seen in parallel programming languages, including barriers, clocks, and point-to-point synchronization using latches or semaphores. This work characterizes scheduling constraints on phaser operations, by relating the execution state of two tasks that operate on the same phaser. We propose a formalization of Habanero phasers, May-Happen-In-Parallel, and Happens-Before relations for phaser operations, and show that these relations conform with the semantics. Our formalization and proofs are fully mechanized using the Coq proof assistant, and are available online.Comment: In Proceedings PLACES 2016, arXiv:1606.0540

The Eureka Programming Model for Speculative Task Parallelism

In this paper, we describe the Eureka Programming Model (EuPM) that simplifies the expression of speculative parallel tasks, and is especially well suited for parallel search and optimization applications. The focus of this work is to provide a clean semantics for, and efficiently support, such "eureka-style" computations (EuSCs) in general structured task parallel programming models. In EuSCs, a eureka event is a point in a program that announces that a result has been found. A eureka triggered by a speculative task can cause a group of related speculative tasks to become redundant, and enable them to be terminated at well-defined program points. Our approach provides a bound on the additional work done in redundant speculative tasks after such a eureka event occurs. We identify various patterns that are supported by our eureka construct, which include search, optimization, convergence, and soft real-time deadlines. These different patterns of computations can also be safely combined or nested in the EuPM, along with regular task-parallel constructs, thereby enabling high degrees of composability and reusability. As demonstrated by our implementation, the EuPM can also be implemented efficiently. We use a cooperative runtime that uses delimited continuations to manage the termination of redundant tasks and their synchronization at join points. In contrast to current approaches, EuPM obviates the need for cumbersome manual refactoring by the programmer that may (for example) require the insertion of if checks and early return statements in every method in the call chain. Experimental results show that solutions using the EuPM simplify programmability, achieve performance comparable to hand-coded speculative task-based solutions and out-perform non-speculative task-based solutions

Linear Promises: Towards Safer Concurrent Programming (Artifact)

We present a compiler for a concurrent programming language, which utilizes linear typing to create a safer promise abstraction. The compiler is implemented in OCaml and produces source-level Java code. We provide example programs to demonstrate use of the language, as well as translations of incorrect JavaScript code from StackOverflow to showcase the ability of our language to catch many classes of bugs. Finally, we provide a minimal runtime environment to allow the execution of compiled programs

Fast neutron star cooling in light of the PREX-2 experiment

The nuclear symmetry energy and its behaviour with density has been recently evaluated with enhanced value by PREX-2 experiment. This new values enables direct Urca neutrino emission process to be functioning in the dense matter inside neutron stars. With this new outlook we study the cooling rate of canonical mass neutron stars and compare with available observational cooling data. We find most of the isolated neutron star thermal profile is compatible with the cooling of canonical mass star including superfluidity suppression.Comment: 8 pages, 5 figures. Accepted for publication in Phys. Rev.

Notes on Günther’s Oriental Slender Snake (Trachischium guentheri) from the Himalayan Realm of North Sikkim, India

The Indian Himalayan Region (IHR) is known for its biodiversity, yet it faces substantial threats fromanthropogenic activities and climate change. Despite the ecological importance of the IHR, herpetofaunal studies,especially in the eastern Himalayan State of Sikkim, remain limited. We herein address aspects of natural history ofa fossorial snake, Günther’s Oriental Slender Snake (Trachischium guentheri) in North Sikkim. We encountered 25snakes during field surveys from 30 September to 12 October 2023 in the Lachen region at elevations of 2,549–2,918m asl. Responses of snakes to unusually high rainfall led to increased road mortality during the peak tourist season. Inresponse, we propose two specialized structures, featuring elevated barriers and elaborate hollow, trapezoidal concreteslabs, to mitigate roadkills. We also emphasize the importance of monitoring to identify areas with high traffic wheremeasures to mitigate road mortality should be employed

Indian perspective about COVID-19 vaccine: an elixir bringing ray of hope to the dark pandemic

India has finally begun its colossal coronavirus vaccine drive, desperately hoping to end a deadly pandemic that has killed around 1.5 lakh of its population. With an aim to vaccinate about 300 million people across the subcontinent by July, India has a huge task ahead. This large number roughly amounts to almost the entire US population