Foundations for practical network verification

Computer networks are large and complex and the often manual process of configuring such systems is error-prone, leading to network outages and breaches. This has ignited research into network verification tools that given a set of operator intents, automatically check whether the configured network satisfies the intents. In this dissertation, we argue that existing works in this area have important limitations that prevent their widespread adoption in the real world. We set to address these limitations by revisiting the main aspects of network verification: verification framework, intent specification, and network modeling. First, we develop #PEC, a symbolic packet header analysis framework that resolves the tension between expressiveness and efficiency in previous works. We provide an extensible library of efficient match-types that allows encoding and analyzing more types of forwarding rules (e.g. Linux iptables) compared to most previous works. Similar to the state-of-the-art, #PEC partitions the space of packet headers into a set of equivalence classes (PECs) before the analysis. However, it uses a lattice-based approach to do so, refraining from using computationally expensive negation and subtraction operations. Our experiments with a broad range of real-world datasets show that #PEC is 10× faster than similarly expressive state-of-the-art. We also demonstrate how empty PECs in previous works lead to unsound/incomplete analysis and develop a counting-based method to eliminate empty PECs from #PEC that outperforms baseline approaches by 10 − 100×. Next, we note that network verification requires formal specifications of the intents of the network operator as a starting point, which are almost never available or even known in a complete form. We mitigate this problem by providing a framework to utilize existing low-level network behavior to infer the high-level intents. We design Anime, a system that given observed packet forwarding behavior, mines a compact set of possible intents that best describe the observations. Anime accomplishes this by applying optimized clustering algorithms to a set of observed network paths, encoded using path features with hierarchical values that yield a way to control the precision-recall tradeoff. The resulting inferred intents can be used as input to verification/synthesis tools for continued maintenance. They can also be viewed as a summary of network behavior, and as a way to find anomalous behavior. Our experiments, including data from an operational network, demonstrate that Anime produces higher quality (F-score) intents than past work, can generate compact summaries with minimal loss of precision, is resilient to imperfect input and policy changes, scales to large networks, and finds actionable anomalies in an operational network. Finally, we turn our attention to modeling networking devices. We envision basing data plane analysis on P4 as the modeling language. Unlike most tools, we believe P4 analysis must be based on a precise model of the language rather than its informal specification. To this end, we develop a formal operational semantics of the P4 language during the process of which we have identified numerous issues with the design of the language. We then provide a suite of formal analysis tools derived directly from our semantics including an interpreter, a symbolic model checker, a deductive program verifier, and a program equivalence checker. Through a set of case studies, we demonstrate the use of our semantics beyond just a reference model for the language. This includes applications for the detection of unportable code, state-space exploration, search for bugs, full functional verification, and compiler translation validation

A formal semantics of P4 and applications

Programmable packet processors and P4 as a programming language for such devices have gained significant interest, because their flexibility enables rapid development of a diverse set of applications that work at line rate. However, this flexibility, combined with the complexity of devices and networks, increases the chance of introducing subtle bugs that are hard to discover manually. Worse, this is a domain where bugs can have catastrophic consequences, yet formal analysis tools for P4 programs and networks are missing. We argue that formal analysis tools must be based on a formal semantics of the target language, rather than on its informal specification. To this end, we provide an executable formal semantics of the P4 language in the K framework. Based on this semantics, K provides an interpreter and various analysis tools including a symbolic model checker and a deductive program verifier. This thesis overviews our formal K semantics of P4, as well as several P4 language design issues that we found during our formalization process. We also discuss some applications resulting from the tools provided by K for P4 programmers and network administrators as well as language designers and compiler developers, such as detection of unportable code, state space exploration of P4 programs and networks, bug finding using symbolic execution, data plane verification, program verification, and translation validation

Psihijatrijski poremećaji u iranskih alkoholičara

Introduction: - there is a close relationship between alcohol dependence and psychiatric disorders. A large number of people who use alcohol are suffering from psychiatric disorders, so identifying and treating of psychiatric disorder is vitally important in alcohol users. The aim of this study was evaluate the prevalence of axis I psychiatric disorders in Iranian alcohol users in 2017. Subjects & Methods: - in this cross-sectional study, 105 patients who were attendance to the Iranian National Center for Addiction Studies (INCAS) were interviewed. Alcohol consumption questionnaire and demographic questionnaire were completed for all patients and the prevalence of psychiatric disorders with SCID-1 was evaluated. The information collected was analyzed with SPSS software version 22. Results: - about 45% of participants except alcohol use had no other psychiatric illness and 55% had psychiatric disorders. 5.34% had bipolar disorders and 4.22% had severe depression, respectively, and the incidence of OCD was in 2.5%. History of referral to the psychiatrist was in 23.8% and history of admission to the psychiatric ward was 16.2%. Also, the use of other non-alcoholic substances in the patients was examined; the most consumed was opium in 26.7%, followed by cannabis with 16.2%. Conclusion: - regarding the high prevalence of axis I psychiatric disorders among alcohol use disorders, a complete interview and history of psychiatry disorders is essential.Uvod: postoji uska povezanost između alkoholne ovisnosti i psihijatrijskih poremećaja. Veliki broj ljudi koji konzumiraju alkohol pate od psihijatrijskih poremećaja, stoga identificiranje i liječenje psihijatrijskog poremećaja je od vitalne važnosti kod korisnika alkohola. Cilj ove studija je istražiti prevalenciju psihijatrijskih poremećaja kod iranskih korisnika alkohola u 2017g. Predmeti i metode: - u ovom presječnom istraživanju anketirano je 105 pacijenata koji su bili na iranskom Nacionalnom centru za studije ovisnosti (INCAS). Svi bolesnici ispunjavali su upitnik za konzumaciju alkohola i demografski upitnik, a prevalencija psihijatrijskih poremećaja procijenjena je s SCID-1. Prikupljeni podaci analizirani su s softverom SPSS verzija 22. Rezultati: - oko 45% sudionika, osim konzumiranja alkohola, nije imalo drugu psihijatrijsku bolest, a 55% je imalo psihijatrijski poremećaj. 5,34% imalo je bipolarni poremećaj, a 4,22% imalo je tešku depresiju, dok je učestalost OCD-a bila 2,5%. Povijest upućivanja psihijatru bila je 23,8%, a povijest primanja na psihijatrijski odjel bila je 16,2%. Također, kod bolesnika je ispitana upotreba drugih ne-alkoholnih supstanci; najviše se konzumirao opijum sa 26,7%, a slijedio je kanabis sa 16,2%. Zaključak: - s obzirom na veliku učestalost psihijatrijskih poremećaja među poremećajima upotrebe alkohola, neophodan je cjelovit intervju i dobivanje povijesti psihijatrijskih poremećaja

Postmastectomy locoregional recurrence and recurrence-free survival in breast cancer patients

<p>Abstract</p> <p>Background</p> <p>One essential outcome after breast cancer treatment is recurrence of the disease. Treatment decision is based on assessment of prognostic factors of breast cancer recurrence. This study was to investigate the prognostic factors for postmastectomy locoregional recurrence (LRR) and survival in those patients.</p> <p>Methods</p> <p>114 patients undergoing mastectomy and adjuvant radiotherapy in Cancer Institute of Tehran University of Medical Sciences were retrospectively reviewed between 1996 and 2008. All cases were followed up after initial treatment of patients with breast cancer via regular visit (annually) for discovering the LRR. Cumulative recurrence free survival (RFS) was determined using the Kaplan-Meier method, with univariate comparisons between groups through the log-rank test. The Cox proportional hazards model was used for multivariate analysis.</p> <p>Result</p> <p>The median follow up time was 84 months (range 2-140). Twenty-three (20.2%) patients developed LRR. Cumulative RFS rate at 2.5 years and 5 years were 86% (95%CI, 81-91) and 82.5% (95%CI, 77-87) respectively. Mean RFS was 116.50 ± 4.43 months (range, 107.82 - 125.12 months, 95%CI). At univariate and multivariate analysis, factors had not any influence on the LRR.</p> <p>Conclusion</p> <p>Despite use of adjuvant therapies during the study, we found a LRR rate after mastectomy of 20.2%. Therefore, for patients with LRR without evidence of distant disease, aggressive multimodality therapy is warranted.</p

Impact of education on knowledge and attitude of medical students about the abuse of prescription drugs in Iran

Introduction: The abuse of prescription drugs is considered as an important challenge for societies. Regarding many factors contributing to this challenge and its negative impact especially on young and educated people, there is an attempt in this paper to survey the impact of education on knowledge and attitude of medical students about the abuse of prescription drugs.Material and Methods: This was a quasi-experimental study, which was conducted on medical students. Two groups of 53 medical students were selected as participants for both intervention group and control group. These participants were studied using the researcher-made questionnaires about knowledge and attitude toward the abuse of prescription drugs.Results: Education plays a significant role in both raising the students’ awareness and changing their attitude about the abuse of prescription drugs. The age variable had a significant relationship with pre-training knowledge. The female participants had less pre-training knowledge about drug abuse so that it was not observed after intervention.Discussion: It is suggested that education can be considered as a strategy to prevent drug abuse and reduce the demand for drug abuse by raising the awareness and amending the attitudes as well as promoting the anti-consumption culture

A Survey of the Relationship between Earnings Management and Qualified Auditor Opinion in Tehran Stock Exchange

This study aims to evaluate the effect of earnings management on type of auditor report in the companies listed on Tehran Stock Exchange (TSE). To measure earnings management, the modified Jones model based on discretionary accruals is used. The audit report is qualified opinion due to the uncertainty in activity and qualified report due to some reasons except uncertainty in going concern. To test the study hypotheses, the data of 80 companies listed on TSE are used as study sample during 2009-2013 by logistic regression model. In the present study, besides testing the relationship between earnings management and qualified auditor opinion, the effect of financial distresses on the relevant relationship is studied. The results of study show the positive and significant relationship between earnings management and qualified opinion regarding some items except going-concern uncertainty. There is no significant relationship between earnings management and qualified opinion in financially distressed companies. Keywords: Earnings management, Qualified audit opinion, Going-concern uncertainty, Financially distressed companies JEL Classifications: D53, M4

Reporting a Case of Injecting Methylphenidate (Ritalin) Tablets, Intensified Symptoms of Schizoph-renia or Induce Separate Mental Disorder

Abstract Background: Methylphenidate is one of the classic amphetamines which can cause or exacerbate psychotic symptoms in schizophrenia patients. Methods: In this paper, a young man is presented with injection of methylphenidate tablets with acute cellulitis due to this injection and the related symptoms. In the first hospitalization and after recovery from psychotic disorder due to tablet injections, he was under treatment with anti-psychotics because of other symptoms related to schizophrenia. Although the patient was regularly under schizophrenic medication after discharge, he was hospitalized twice more due to psychotic symptoms that appeared after injecting methylphenidate. Findings: This report shows psychotic symptoms in schizophrenic patients after injecting methylphenidate. These symptoms cannot be prevented even by anti-psychotic medication of background disease. This case shows the existence of two kinds of psychoses, functional (due to schizophrenia) and organic psychoses (due to methylphenidate use) in the same patient. Keywords: Methylphenidate, Injection, Schizophrenia, Psychotic disorders

Prevalence of Cigarette Smoking in Schizophrenic Patients Compared to Other Hospital Admitted Psychiatric Patients

Abstract This study aimed to estimate the prevalence of cigarette smoking and some of the related factors among schizophrenic and other hospitalized psychiatric patients. This was a cross-sectional study on 120 patients hospitalized in Shahid Beheshti hospital in Kerman in 2005. Patients were equally devided in two groups of schizophrenia and other psychiatric disorders. Sampling was based on statistical census and data were collected using a questionnaire including 27 questions on demographic data, psychiatric disorder, smoking cigarettes and other substances, and Fagerstrom test. Data were analyzed by Chi-square and ANOVA tests using SPSS software. Prevalence and severity of cigarette smoking was 71.6% and 6.47% among schizophrenic and 51.6% and 6.40% among other psychiatric patients, respectively and the difference was not significant. History of withdrawal was 25.6% and 58.1% in the schizophrenia and other disorders respectively and the difference was significant (P < 0.05). Addiction to other substances was 51.6% in schizophrenic and 45% in the other patients and the most prevalent substances in both groups were opium and alcohol. The severity of smoking cigarettes was 6.9 along with other drug abuses and 5.1 in cases with just smoking based on Fagerstrom test and the difference was significant (P < 0.05). The prevalence of cigarette smoking in both schizophrenia and other psychiatric patients is higher than normal population, but there is no significant difference between these two groups. Schizophrenic patients need persistent supportive and supervising programs for cigarette smoking abuse treatment because of their cognitive, motivate and social problems

Evaluation of the Young Children with Neurodevelopmental Disability: A Prospective Study at Hamadan University of Medical Sciences Clinics

How to Cite This Article: Fayyazi A, Kheizrian L, Kheradmand Z, Damadi S, Khajeh A. Evaluation of the Young Children with Neurodevelopmental Disability: A Prospective Study at Hamadan University of Medical Sciences Clinics. Iran J Child Neurol. 2013 Winter; 7 (1):29-33. ObjectiveDevelopmental impairment is a common problem in children health that occurs in approximately 5–10% of the childhood population. The aim of this study was to determine the etiologic yield of subspecialists’ evaluation of young children with developmental disability.Materials &amp; MethodsAll children aged between 2 months and 5 years referred over a 15-month period to Hamadan University of Medical Sciences subspecialty services for initial evaluation of a suspected developmental Disability, were enrolled in the present study. Diagnostic yield was determined after the completion of clinical assessments and laboratory tests requested by the evaluating physician.ResultsA total of 198 children (129 boys and 69 girls) were eligible for our study.108 children had global developmental delay and 90 children had isolated developmental delay. Approximately ¼ of all patients did not have any specific etiology for developmental disability. Cerebral palsy (CP) was the most common clinical syndrome in all patients (41.4%). Hypoxic ischemic encephalopathy (13.8%), brain dysgenesis (13%), genetic disorder (13%), and  neurodegenerative  diseases  (11%)  were  determined  in  more  than one half of all children with global developmental disability. in our study, “developmental speech delay” was the common cause of isolated speech delay.ConclusionDetermination of an underlying etiology is an essential part of specialty evaluation of young children with developmental disability. The results of this study were similar closely to the results of other studies. ReferencesBernard LM. Current Management in Child Neurology. 3rd ed. London: BC Decker Inc; 2005. pp. 3-8 and 246-50.Cleary M A, Green A. Developmental delay: when to suspect and how to investigate for an inborn error of metabolism. Arch Dis Child 2005;90(11):1128–32.Glascoe FP, Dworkin PH. Obstacles to effective developmental surveillance: errors in clinical reasoning. J Dev Behav Pediatrics 1993;14(5):344–9.Shaffer LG. American College of Medical Genetics guideline on the cytogenetic evaluation of the individual with developmental delay or mental retardation. Genet Med 2005;7:650-4.Nelson HD, Nygren P, Walker M, Panoscha R. Screening for Speech and Language Delay in Preschool Children: Systematic Evidence Review for the US Preventive Services Task Force. Pediatrics 2006;117(2):e 297-319.Leung AK, Kao CP. Evaluation and Management of the Child with Speech Delay. Am Fam Physician 1999; 59(11):3121-28.Bosley A. Developmental delay versus developmental impairment. Arch Dis Child 2005; 90(8):875.Matson JL, Mahan S, LoVullo SV. Parent training: a review of methods for children with developmental disabilities. Res Dev Disabils 2009;30(5): 961–8.Shevell M, Ashwal S, Donley D, Flint J, Gingold M, Hirtz D, et al. Practice parameter: evaluation of the child with global developmentaldelay: report of the Quality Standards Subcommittee of the American Academy of Neurology and The Practice Committee of the Child Neurology Society. Neurology 2003;60(3):367-80.McDonald L, Rennie A, Tolmie J, Galloway P, McWilliam R. Investigation of global developmental delay. Arch Dis Child 2006;91(8):701–5.Miller DT, Adam MP, Aradhya S, Biesecker LG, Brothman AR, Carter NP, et al. Consensus Statement: Chromosomal Microarrayc Is a First-Tier Clinical Diagnostic Test for Individuals with Developmental Disabilities or Congenital Anomalies. Am J Hum Genet 2010;86(5):749–64.Stankiewicz P, Beaude AL. Use of array CGH in the     evaluation of dysmorphology, malformations, developmental delay, and idiopathic mental retardation. Curr Opin Genet Dev 2007;17(3):182-92.Sherr EH, Shevell MI. Global Developmental Delay and Mental Retardation/Intellectual Disability. In: Swaiman KF, Ashwal S, Ferriro DM, Schor NF, editors. Swaiman’s Pediatric Neurology. 5th ed. China: Elsevier Saunders; 2012. p. 554-74.Shevel MI, Majnemer A, Rosenbawn P, Abrahamowiez M. Etiologic yield of subspecialists’ evaluation of young children with global developmental delay. J Pediatr 2000 May;136(5):593-8.Tikaria A, Kabara M, Gupta N, Sapra S, Balakrishnan P, Gulati S, et al. Aetiology of global developmental delay in young children: experience from a tertiary care center in India. Natl Med J India 2010;23(6):324-9.Aggarwal S, Bogula VR, Mandal K, Kumar R, Phadke SR. Aetiologic spectrum of mental retardation &amp; developmental delay in India. Indian J Med Res 2012;136(3):436-44.