Automated verification of shape and size properties via separation logic.

Despite their popularity and importance, pointer-based programs remain a major challenge for program verification. In this paper, we propose an automated verification system that is concise, precise and expressive for ensuring the safety of pointer-based programs. Our approach uses user-definable shape predicates to allow programmers to describe a wide range of data structures with their associated size properties. To support automatic verification, we design a new entailment checking procedure that can handle well-founded inductive predicates using unfold/fold reasoning. We have proven the soundness and termination of our verification system, and have built a prototype system

Beyond reachability: Shape abstraction in the presence of pointer arithmetic

Abstract. Previous shape analysis algorithms use a memory model where the heap is composed of discrete nodes that can be accessed only via access paths built from variables and field names, an assumption that is violated by pointer arithmetic. In this paper we show how this assumption can be removed, and pointer arithmetic embraced, by using an analysis based on separation logic. We describe an abstract domain whose elements are certain separation logic formulae, and an abstraction mechanism that automatically transits between a low-level RAM view of memory and a higher, fictional, view that abstracts from the representation of nodes and multiword linked-lists as certain configurations of the RAM. A widening operator is used to accelerate the analysis. We report experimental results obtained from running our analysis on a number of classic algorithms for dynamic memory management.

SPaCIFY: a Formal Model-Driven Engineering for Spacecraft On-Board Software

International audienceThe aim of this article is to present a model- driven approach proposed by the SPaCIFY project for spacecraft on-board software development. This ap- proach is based on a formal globally asynchronous lo- cally synchronous language called Synoptic, and on a set of transformations allowing code generation and model verification

Almost-BPS Solutions in Multi-Center Taub-NUT

Microstates of multiple collinear black holes embedded in a non-collinear two-center Taub-NUT spacetime are sought in 4 dimensions. A set of coupled partial differential equations are obtained and solved for almost-BPS states, where some supersymmetry is preserved in the context of N = 2 supergravity in 4 dimensions. The regularity of solutions is carefully considered, and we ensure that no CTC (closed time-like curves) are present. The larger framework is that of 11-dimensional N = 2 supergravity, and the current theory is obtained by compactifying it down to 4 dimensions. This work is a generalization (to three non-collinear centers) of a previous paper by Bena et al

Dataflow Analysis for Datarace-Free Programs

Memory models for shared-memory concurrent programming languages typically guarantee sequential consistency (SC) semantics for datarace-free (DRF) programs, while providing very weak or no guarantees for non-DRF programs. In effect programmers are expected to write only DRF programs, which are then executed with SC semantics. With this in mind, we propose a novel scalable solution for dataflow analysis of concurrent programs, which is proved to be sound for DRF programs with SC semantics. We use the synchronization structure of the program to propagate dataflow information among threads without requiring to consider all interleavings explicitly. Given a dataflow analysis that is sound for sequential programs and meets certain criteria, our technique automatically converts it to an analysis for concurrent programs

Angiogenic markers during preeclampsia: Are they associated with hypertension 1 year postpartum?

Objectives: Preeclampsia is associated with hypertension in later life, but the underlying pathophysiological mechanisms remain uncertain. We aimed to explore whether the angiogenic markers soluble Fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) measured in women with preeclampsia could be associated with hypertension 1 year after delivery. Methods: This is a secondary analysis of a prospective cohort study, originally aimed to evaluate the use of sFlt-1/PlGF ratio to predict adverse outcome in women with (suspected) preeclampsia. Office blood pressure (BP) was evaluated at 1 year postpartum in women who had a confirmed diagnosis of preeclampsia within one week of biomarker measurement. Results: Eighty women were included with a median (interquartile range) gestational age (GA) at biomarker measurement of 30 (27–33) weeks. Twenty-three (29%) women had hypertension 1 year postpartum. These women showed higher median SBP during their pregnancy and lower GA at PE diagnosis compared to women without hypertension. Median PlGF levels were lower in women with hypertension 1 year postpartum compared to women without hypertension (23 vs. 48 pg/mL, p = 0.017), while no differences in sFlt-1 or sFlt-1/PlGF ratio were observed. Multivariable analysis adjusted for GA did not show significant association between PlGF (nor sFlt-1, sFlt-1/PlGF ratio) and hypertension 1 yea

HLA-B*5701 screening for hypersensitivity to Abacavir

Background Hypersensitivity reaction to abacavir is strongly associated with the presence of the HLA-B*5701 allele. This study was designed to establish the effectiveness of prospective HLA-B*5701 screening to prevent the hypersensitivity reaction to abacavir. Methods This double-blind, prospective, randomized study involved 1956 patients from 19 countries, who were infected with human immunodeficiency virus type 1 and who had not previously received abacavir. We randomly assigned patients to undergo prospective HLA-B*5701 screening, with exclusion of HLA-B*5701–positive patients from abacavir treatment (prospective-screening group), or to undergo a standard-of-care approach of abacavir use without prospective HLA-B*5701 screening (control group). All patients who started abacavir were observed for 6 weeks. To immunologically confirm, and enhance the specificity of, the clinical diagnosis of hypersensitivity reaction to abacavir, we performed epicutaneous patch testing with the use of abacavir. Results The prevalence of HLA-B*5701 was 5.6% (109 of 1956 patients). Of the patients receiving abacavir, 72% were men, 84% were white, and 18% had not previously received antiretroviral therapy. Screening eliminated immunologically confirmed hypersensitivity reaction (0% in the prospective-screening group vs. 2.7% in the control group, P<0.001), with a negative predictive value of 100% and a positive predictive value of 47.9%. Hypersensitivity reaction was clinically diagnosed in 93 patients, with a significantly lower incidence in the prospective-screening group (3.4%) than in the control group (7.8%) (P<0.001). Conclusions HLA-B*5701 screening reduced the risk of hypersensitivity reaction to abacavir. In predominantly white populations, similar to the one in this study, 94% of patients do not carry the HLA-B*5701 allele and are at low risk for hypersensitivity reaction to abacavir. Our results show that a pharmacogenetic test can be used to prevent a specific toxic effect of a drug

Region-Based Shape Analysis with Tracked Locations

This paper proposes a novel approach to shape analysis: using local reasoning about individual heap locations instead of global reasoning about entire heap abstractions. We present an inter-procedural shape analysis algorithm for languages with destructive updates. The key feature is a novel memory abstraction that differs from traditional abstractions in two ways. First, we build the shape abstraction and analysis on top of a pointer analysis. Second, we decompose the shape abstraction into a set of independent configurations, each of which characterizes one single heap location. Our approach: 1) leads to simpler algorithm specifications, because of local reasoning about the single location; 2) leads to efficient algorithms, because of the smaller granularity of the abstraction; and 3) makes it easier to develop context-sensitive, demand-driven, and incremental shape analyses. We also show that the analysis can be used to enable the static detection of memory errors in programs with explicit deallocation. We have built a prototype tool that detects memory leaks and accesses through dangling pointers in C programs. The experiments indicate that the analysis is sufficiently precise to detect errors with low false positive rates; and is sufficiently lightweight to scale to larger programs. For a set of three popular C programs, the tool has analyzed about 70K lines of code in less than 2 minutes and has produced 97 warnings, 38 of which were actual errors

ACQUIRED DRUG RESISTANCE TO NRTI CLASS IN TREATMENT-EXPERIENCED HIV INFECTED PATIENTS FROM THE CONSTANTA COUNTY: THERAPEUTIC IMPLICATIONS

Objective. To determine the prevalence of acquired drug resistance (ADR) and of resistance patterns in treatment-experienced HIV infected patients from Constanta in order to establish the best therapeutic options in NRTI class. Material and methods. A retrospective study which included 144 treatment-experienced HIV patients with confirmed viral failure. The strains isolated from these patients were analysed in the Molecular Genetic Laboratory of „Matei Bals“ National Institute of Infectious Diseases, Bucharest and the resulting sequences were saved in FASTA format. The HIV-1 subtyping was based on „REGA HIV01&2 Automated subtyping tool version 2.0“ algorithm. „Stanford HIVdb Program version 8.4“ was used in order to determine the therapeutic options. For statistical calculations, the R-Project software was used. Graphic representations were performed using GNUPLOT program. Results. The prevalence of the acquired drug resistance was 92.36%. The most frequent mutation occurred at the level of the codon 184. The TAM-2 path was more frequently selected compared to TAM-1. Association between TAM1 and TAM 2 were also found, mutation K65R being rarely met. Conclusions. The prevalence of the acquired drug resistance in our study was high, The most valuable therapeutic option in the INRT class remains tenofovir, due to the mutational profile, which was selected on account of the extensive use of thymidine analogues