On the Behaviour of General-Purpose Applications on Cloud Storages

Managing data over cloud infrastructures raises novel challenges with respect to existing and well studied approaches such as ACID and long running transactions. One of the main requirements is to provide availability and partition tolerance in a scenario with replicas and distributed control. This comes at the price of a weaker consistency, usually called eventual consistency. These weak memory models have proved to be suitable in a number of scenarios, such as the analysis of large data with Map-Reduce. However, due to the widespread availability of cloud infrastructures, weak storages are used not only by specialised applications but also by general purpose applications. We provide a formal approach, based on process calculi, to reason about the behaviour of programs that rely on cloud stores. For instance, one can check that the composition of a process with a cloud store ensures `strong' properties through a wise usage of asynchronous message-passing

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology

Effective Abstractions for Verification under Relaxed Memory Models

Abstract. We present a new abstract interpretation based approach for automat-ically verifying concurrent programs running on relaxed memory models. Our approach is based on three key insights: (i) behaviors of relaxed models (e.g. TSO and PSO) are naturally captured using explicit encodings of store buffers. Directly using such encodings for program analysis is challenging due to shift op-erations on buffer contents that result in significant loss of analysis precision. We present a new abstraction of the memory model that eliminates expensive shifting of store buffer contents and significantly improves the precision and scalability of program analysis, (ii) an encoding of store buffer sizes that leverages knowl-edge of the abstract interpretation domain, further improving analysis precision, and (iii) a source-to-source transformation that realizes the above two techniques: given a program P and a relaxed memory model M, it produces a new program PM where the behaviors of P running on M are over-approximated by the be-havior of PM running on sequential consistency (SC). This step makes it possible to directly use state-of-the-art analyzers under SC. We implemented our approach and evaluated it on a set of finite and infinite-state concurrent algorithms under two memory models: Intel’s x86 TSO and PSO. Experimental results indicate that our technique achieves better precision and efficiency than prior work: we can automatically verify algorithms with fewer fences, faster and with lower memory consumption.

Generative Operational Semantics for Relaxed Memory Models ⋆

Abstract. The specification of the Java Memory Model (JMM) is phrased in terms of acceptors of execution sequences rather than the standard generative view of operational semantics. This creates a mismatch with language-based techniques, such as simulation arguments and proofs of type safety. We describe a semantics for the JMM using standard programming language techniques that captures its full expressivity. For data-race-free programs, our model coincides with the JMM. For lockless programs, our model is more expressive than the JMM. The stratification properties required to avoid causality cycles are derived, rather than mandated in the style of the JMM. The JMM is arguably non-canonical in its treatment of the interaction of data races and locks as it fails to validate roach-motel reorderings and various peephole optimizations. Our model differs from the JMM in these cases. We develop a theory of simulation and use it to validate the legality of the above optimizations in any program context.