14 research outputs found
Diagrammatic Languages and Formal Verification : A Tool-Based Approach
The importance of software correctness has been accentuated as a growing number of safety-critical systems have been developed relying on software operating these systems. One of the more prominent methods targeting the construction of a correct program is formal verification. Formal verification identifies a correct program as a program that satisfies its specification and is free of defects. While in theory formal verification guarantees a correct implementation with respect to the specification, applying formal verification techniques in practice has shown to be difficult and expensive. In response to these challenges, various support methods and tools have been suggested for all phases from program specification to proving the derived verification conditions. This thesis concerns practical verification methods applied to diagrammatic modeling languages.
While diagrammatic languages are widely used in communicating system design (e.g., UML) and behavior (e.g., state charts), most formal verification platforms require the specification to be written in a textual specification language or in the mathematical language of an underlying logical framework. One exception is invariant-based programming, in which programs together with their specifications are drawn as invariant diagrams, a type of state transition diagram annotated with intermediate assertions (preconditions, postconditions, invariants). Even though the allowed program statesâcalled situationsâare described diagrammatically, the intermediate assertions defining a situationâs meaning in the domain of the program are still written in conventional textual form. To explore the use of diagrams in expressing the intermediate assertions of invariant diagrams, we designed a pictorial language for expressing array properties. We further developed this notation into a diagrammatic domain-specific language (DSL) and implemented it as an extension to the Why3 platform. The DSL supports expression of array properties. The language is based on Reynoldsâs interval and partition diagrams and includes a construct for mapping array intervals to logic predicates.
Automated verification of a program is attained by generating the verification conditions and proving that they are true. In practice, full proof automation is not possible except for trivial programs and verifying even simple properties can require significant effort both in specification and proof stages. An animation tool which supports run-time evaluation of the program statements and intermediate assertions given any user-defined input can support this process. In particular, an execution trace leading up to a failed assertion constitutes a refutation of a verification condition that requires immediate attention. As an extension to Socos, a verificion tool for invariant diagrams built on top of the PVS proof system, we have developed an execution model where program statements and assertions can be evaluated in a given program state. A program is represented by an abstract datatype encoding the program state, together with a small-step state transition function encoding the evaluation of a single statement. This allows the programâs runtime behavior to be formally inspected during verification. We also implement animation and interactive debugging support for Socos.
The thesis also explores visualization of system development in the context of model decomposition in Event-B. Decomposing a software system becomes increasingly critical as the system grows larger, since the workload on the theorem provers must be distributed effectively. Decomposition techniques have been suggested in several verification platforms to split the models into smaller units, each having fewer verification conditions and therefore imposing a lighter load on automatic theorem provers. In this work, we have investigated a refinement-based decomposition technique that makes the development process more resilient to change in specification and allows parallel development of sub-models by a team. As part of the research, we evaluated the technique on a small case study, a simplified version of a landing gear system verification presented by Boniol and Wiels, within the Event-B specification language.Vikten av programvaras korrekthet har accentuerats dÄ ett vÀxande antal sÀkerhetskritiska system, vilka Àr beroende av programvaran som styr dessa, har utvecklas. En av de mer framtrÀdande metoderna som riktar in sig pÄ utveckling av korrekt programvara Àr formell verifiering. Inom formell verifiering avses med ett korrekt program ett program som uppfyller sina specifikationer och som Àr fritt frÄn defekter. Medan formell verifiering teoretiskt sett kan garantera ett korrekt program med avseende pÄ specifikationerna, har tillÀmpligheten av formella verifieringsmetod visat sig i praktiken vara svÄr och dyr. Till svar pÄ dessa utmaningar har ett stort antal olika stödmetoder och automatiseringsverktyg föreslagits för samtliga faser frÄn specifikationen till bevisningen av de hÀrledda korrekthetsvillkoren. Denna avhandling behandlar praktiska verifieringsmetoder applicerade pÄ diagrambaserade modelleringssprÄk.
Medan diagrambaserade sprĂ„k ofta anvĂ€nds för kommunikation av programvarudesign (t.ex. UML) samt beteende (t.ex. tillstĂ„ndsdiagram), krĂ€ver de flesta verifieringsplattformar att specifikationen kodas medelst ett textuellt specifikationsspĂ„k eller i sprĂ„ket hos det underliggande logiska ramverket. Ett undantag Ă€r invariantbaserad programmering, inom vilken ett program tillsammans med dess specifikation ritas upp som sk. invariantdiagram, en typ av tillstĂ„ndstransitionsdiagram annoterade med mellanliggande logiska villkor (förvillkor, eftervillkor, invarianter). Ăven om de tillĂ„tna programtillstĂ„ndenâsk. situationerâbeskrivs diagrammatiskt Ă€r de logiska predikaten som beskriver en situations betydelse i programmets domĂ€n fortfarande skriven pĂ„ konventionell textuell form. För att vidare undersöka anvĂ€ndningen av diagram vid beskrivningen av mellanliggande villkor inom invariantbaserad programming, har vi konstruerat ett bildbaserat sprĂ„k för villkor över arrayer. Vi har dĂ€refter vidareutvecklat detta sprĂ„k till ett diagrambaserat domĂ€n-specifikt sprĂ„k (domain-specific language, DSL) och implementerat stöd för det i verifieringsplattformen Why3. SprĂ„ket lĂ„ter anvĂ€ndaren uttrycka egenskaper hos arrayer, och Ă€r baserat pĂ„ Reynolds intevall- och partitionsdiagram samt inbegriper en konstruktion för mappning av array-intervall till logiska predikat.
Automatisk verifiering av ett program uppnÄs genom generering av korrekthetsvillkor och Ätföljande bevisning av dessa. I praktiken kan full automatisering av bevis inte uppnÄs utom för trivial program, och Àven bevisning av enkla egenskaper kan krÀva betydande anstrÀngningar bÄde vid specifikations- och bevisfaserna. Ett animeringsverktyg som stöder exekvering av sÄvÀl programmets satser som mellanliggande villkor för godtycklig anvÀndarinput kan vara till hjÀlp i denna process. SÀrskilt ett exekveringspÄr som leder upp till ett falskt mellanliggande villkor utgör ett direkt vederlÀggande (refutation) av ett bevisvillkor, vilket krÀver omedelbar uppmÀrksamhet frÄn programmeraren. Som ett tillÀgg till Socos, ett verifieringsverktyg för invariantdiagram baserat pÄ bevissystemet PVS, har vi utvecklat en exekveringsmodell dÀr programmets satser och villkor kan evalueras i ett givet programtillstÄnd. Ett program representeras av en abstrakt datatyp för programmets tillstÄnd tillsammans med en small-step transitionsfunktion för evalueringen av en enskild programsats. Detta möjliggör att ett programs exekvering formellt kan analyseras under verifieringen. Vi har ocksÄ implementerat animation och interaktiv felsökning i Socos.
Avhandlingen undersöker ocksÄ visualisering av systemutveckling i samband med modelluppdelning inom Event-B. Uppdelning av en systemmodell blir allt mer kritisk dÄ ett systemet vÀxer sig större, emedan belastningen pÄ underliggande teorembe visare mÄste fördelas effektivt. Uppdelningstekniker har föreslagits inom mÄnga olika verifieringsplattformar för att dela in modellerna i mindre enheter, sÄ att varje enhet har fÀrre verifieringsvillkor och dÀrmed innebÀr en mindre belastning pÄ de automatiska teorembevisarna. I detta arbete har vi undersökt en refinement-baserad uppdelningsteknik som gör utvecklingsprocessen mer kapabel att hantera förÀndringar hos specifikationen och som tillÄter parallell utveckling av delmodellerna inom ett team. Som en del av forskningen har vi utvÀrderat tekniken pÄ en liten fallstudie: en förenklad modell av automationen hos ett landningsstÀll av Boniol and Wiels, uttryckt i Event-B-specifikationsprÄket
Intra-arterial verapamil improves functional outcomes of thrombectomy in a preclinical model of extended hyperglycemic stroke
The abrupt hyperglycemic reperfusion following thrombectomy has been shown to harm the efficacy of the intervention in stroke patients with large vessel occlusion. Studies of ours and others have shown thioredoxin-interacting protein (TXNIP) is critically involved in hyperglycemic stroke injury. We recently found verapamil ameliorates cerebrovascular toxicity of tissue plasminogen activators in hyperglycemic stroke. The present study aims to answer if verapamil exerts direct neuroprotective effects and alleviates glucose toxicity following thrombectomy in a preclinical model of hyperglycemic stroke. Primary cortical neural (PCN) cultures were exposed to hyperglycemic reperfusion following oxygen-glucose deprivation (OGD), with or without verapamil treatment. In a mouse model of intraluminal stroke, animals were subjected to 4Â h middle cerebral artery occlusion (MCAO) and intravenous glucose infusion. Glucose infusion lasted one more hour at reperfusion, along with intra-arterial (i.a.) verapamil infusion. Animals were subjected to sensorimotor function tests and histological analysis of microglial phenotype at 72Â h post-stroke. According to our findings, glucose concentrations (2.5â20Â mM) directly correlated with TXNIP expression in OGD-exposed PCN cultures. Verapamil (100Â nM) effectively improved PCN cell neurite growth and reduced TXNIP expression as well as interaction with NOD-like receptor pyrin domain-containing-3 (NLRP3) inflammasome, as determined by immunoblotting and immunoprecipitation. In our mouse model of extended hyperglycemic MCAO, i.a. verapamil (0.5Â mg/kg) could attenuate neurological deficits induced by hyperglycemic stroke. This was associated with reduced microglial pro-inflammatory transition. This finding encourages pertinent studies in hyperglycemic patients undergoing thrombectomy where the robust reperfusion may exacerbate glucose toxicity
Research Paper: Using Subpubic Angle in Sex Determination and Stature Estimation: An Anthropometric Study on Iranian Adult Population
Background: Pelvic bone has important sex determining features. However, anthropometric reference values vary by study population. This study aimed to determine the accuracy of subpubic angle for sex determination and height estimation in Iranian adults.Methods: In this study, the subpubic angle in the digital pelvic radiographs of 325 Iranian adults (199 males and 126 females) and their standing heights were measured. Then, the relation of subpubic angle with sex and stature was evaluated. Results: The mean(SD) subpubic angle of the studied population was 116.3 (23.7) degrees. Subpubic angle was significantly wider (P<0.001) in females [140.5(14.3) degrees] compared to males [101.0(13.3) degrees]. Moreover, we observed a significant decrease (P<0.001) in femalesâ subpubic angle with an increase in age. A significant reverse correlation (P<0.01) was also observed between the subpubic angle and height (r=0.416). Conclusion: This study showed that the mean subpubic angle in Iranian adults is different from the average in other populations. Our reference values can be used in forensic identification
Learning and Memory Impairment Induced by Amyloid Beta Peptide and Effects of Thymol on Hippocampal Synaptic Plasticity in Rats Fed a High-Fat Diet That Received Amyloid Beta
Thymol is a natural phenolic compound that is present in various plants; the significant antioxidant activities of Thymol may be helpful in preventing the progress of various oxidative stress-related diseases. Recent studies have confirmed that antioxidant-rich foods play a vital role in the disease prevention of neurodegenerative diseases, including Alzheimerâs disease (AD). We examined the protective and therapeutic effects of Thymol on the AÎČ-induced long-term potentiation (LTP) impairments in rats fed a high-fat diet. LTP is a type of synaptic activity that has been thoroughly studied in the hippocampus and is thought to be the neural correlate of learning and memory. If Thymol is protective against AD-related impairments, then natural therapeutic agents based on the structure of Thymol could be used to protect against oxidative stress-related illnesses, such as AD
Global burden of peripheral artery disease and its risk factors, 1990â2019 : a systematic analysis for the Global Burden of Disease Study 2019
peripheral artery disease were modelled using the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) 2019 database. Prevalence, disability-adjusted life years (DALYs), and mortality estimates of peripheral artery disease were extracted from GBD 2019. Total DALYs and age-standardised DALY rate of peripheral artery disease attributed to modifiable risk factors were also assessed.
Findings
In 2019, the number of people aged 40 years and older with peripheral artery disease was 113 million (95% uncertainty interval [UI] 99·2â128·4), with a global prevalence of 1·52% (95% UI 1·33â1·72), of which 42·6% was in countries with low to middle Socio-demographic Index (SDI). The global prevalence of peripheral artery disease was higher in older people, (14·91% [12·41â17·87] in those aged 80â84 years), and was generally higher in females than in males. Globally, the total number of DALYs attributable to modifiable risk factors in 2019 accounted for 69·4% (64·2â74·3) of total peripheral artery disease DALYs. The prevalence of peripheral artery disease was highest in countries with high SDI and lowest in countries with low SDI, whereas DALY and mortality rates showed U-shaped curves, with the highest burden in the high and low SDI quintiles.
Interpretation
The total number of people with peripheral artery disease has increased globally from 1990 to 2019. Despite the lower prevalence of peripheral artery disease in males and low-income countries, these groups showed similar DALY rates to females and higher-income countries, highlighting disproportionate burden in these groups. Modifiable risk factors were responsible for around 70% of the global peripheral artery disease burden. Public measures could mitigate the burden of peripheral artery disease by modifying risk factors
Hyperpyrexia After Rectal Misoprostol Administration-A Rare Side Effect of Misoprostol: Case Report: Misoprostol and Hyperpyrexia
Background: Misoprostol is a safe drug that is one of the prostaglandins analogs. It has uterotonic solid potential and is good for postpartum hemorrhage (PPH). Misoprostol has some side effects; hyperpyrexia is a rare side effect after misoprostol administration.Cases Report: A 21-year- woman, Gravid 1 Parity 1, 18 hours after cesarean section, suffered from uterus atonyand vaginal bleeding that rectal misoprostol was administered. Her PPH was managed with misoprostol and other uterotonics. She developed a fever, and because of the Coronavirus disease (covid-19) pandemic, we suspected it and assayed it, but it was negative.Conclusion: In this rare case, hyperpyrexia occurred after rectal misoprostol administration because of dose and prostaglandin effect on the hypothalamus. In this critical situation that covid-19 is pandemic, we suggest tospecialists that keep in mind fever and hyperpyrexia may occur consequently the misoprostol administration
The Effect of Verbal Intelligence on Knowledge of Lexicon
The present study was conducted to investigate the effect of verbal intelligence on Iranian pre-intermediate studentsâ knowledge of lexicon. The participants comprised of 30 male and 30 female learners. A vocabulary test was administered to find out studentsâ vocabulary knowledge and also Wechsler intelligence test was administered for both groups of male and female to find out studentsâ verbal intelligence, of course the verbal part of intelligence was needed due to the topic of study. Analysis of the result revealed that the participants who had higher verbal intelligence also had higher marks in vocabulary test and the participants who had lower verbal intelligence had a lower mark in vocabulary test.
The comparison of side effects of methyldopa, amlodipine, and metoprolol in pregnant women with chronic hypertension
Objective The aim of the study was to compare the complication of Antihypertensive drug; in pregnant women with chronic hypertension. Method This retrospective cohort study was performed on 300 pregnant women  with chronic hypertension. Results:  a relative risk of preeclampsia among methyldopa group was 3.45 times higher than the metoprolol, the relative risk of preterm labor was not significantly between methyldopa and metoprolol group, LBW, and IUGR in methyldopa and amlodipine groups . Conclusion Methyldopa and amlodipine are associated with the least side effects in pregnant women treated for chronic hypertension.the incidence of preeclampsia was greater in methyldopa group