Formal Modeling and Analysis of the Walter Transactional Data Store

Walter is a distributed partially replicated data store providing Parallel Snapshot Isolation (PSI), an important consistency property that offers attractive performance while ensuring adequate guarantees for certain kinds of applications. In this work we formally model Walter's design in Maude and formally specify and verify PSI by model checking. To also analyze Walter's performance we extend the Maude specification of Walter to a probabilistic rewrite theory and perform statistical model checking analysis to evaluate Walter's throughput for a wide range of workloads. Our performance results are consistent with a previous experimental evaluation and throw new light on Walter's performance for different workloads not evaluated before.Ope

Design, Formal Modeling, and Validation of Cloud Storage Systems using Maude

To deal with large amounts of data while offering high availability, throughput and low latency, cloud computing systems rely on distributed, partitioned, and replicated data stores. Such cloud storage systems are complex software artifacts that are very hard to design and analyze. We argue that formal specification and model checking analysis should significantly improve their design and validation. In particular, we propose rewriting logic and its accompanying Maude tools as a suitable framework for formally specifying and analyzing both the correctness and the performance of cloud storage systems. This chapter largely focuses on how we have used rewriting logic to model and analyze industrial cloud storage systems such as Google's Megastore, Apache Cassandra, Apache ZooKeeper, and RAMP. We also touch on the use of formal methods at Amazon Web Services.This work is based on research sponsored by the Air Force Research Laboratory and the Air Force Office of Scientific Research, under agreement number FA8750-11-2-0084. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. This work is also based on research supported by the National Science Foundation under Grant Nos. NSF CNS 1409416 and NSF CNS 1319527.Ope

Automatic Analysis of Consistency Properties of Distributed Transaction Systems in Maude

Many transaction systems distribute, partition, and replicate their data for scalability, availability, and fault tolerance. However, observing and maintaining strong consistency of distributed and partially replicated data leads to high transaction latencies. Since different applications require different consistency guarantees, there is a plethora of consistency properties---from weak ones such as read atomicity through various forms of snapshot isolation to stronger serializability properties---and distributed transaction systems (DTSs) guaranteeing such properties. This paper presents a general framework for formally specifying a DTS in Maude, and formalizes in Maude nine common consistency properties for DTSs so defined. Furthermore, we provide a fully automated method for analyzing whether the DTS satisfies the desired property for all initial states up to given bounds on system parameters. This is based on automatically recording relevant history during a Maude run and defining the consistency properties on such histories. To the best of our knowledge, this is the first time that model checking of all these properties in a unified, systematic manner is investigated. We have implemented a tool that automates our method, and use it to model check state-of-the-art DTSs such as P-Store, RAMP, Walter, Jessy, and ROLA.Ope

A Systematic Review of Online Sex Addiction and Clinical Treatments Using CONSORT Evaluation

Researchers have suggested that the advances of the Internet over the past two decades have gradually eliminated traditional offline methods of obtaining sexual material. Additionally, research on cybersex and/or online sex addictions has increased alongside the development of online technology. The present study extended the findings from Griffiths’ (2012) systematic empirical review of online sex addiction by additionally investigating empirical studies that implemented and/or documented clinical treatments for online sex addiction in adults. A total of nine studies were identified and then each underwent a CONSORT evaluation. The main findings of the present review provide some evidence to suggest that some treatments (both psychological and/or pharmacological) provide positive outcomes among those experiencing difficulties with online sex addiction. Similar to Griffiths’ original review, this study recommends that further research is warranted to establish the efficacy of empirically driven treatments for online sex addiction

Morbidity, life style and psychosocial situation in cancer survivors aged 60-69 years: results from The Nord-Trøndelag Health Study (The HUNT-II Study)

<p>Abstract</p> <p>Background</p> <p>Due to considerable health status differences in the elderly population, research limited to narrow age-spans might be an advantage. In this population-based controlled study we compare short-term (<5 years) (STS) and long-term (≥5 years) (LTS) cancer survivors and cancer-free controls aged 60-69 years from two Norwegian health registers; the Health Survey of North-Trøndelag County (HUNT-2 study) and the Cancer Registry of Norway (CRN). We examined possible factors associated with being cancer survivor.</p> <p>Methods</p> <p>Among 9,089 individuals aged 60-69 who participated in HUNT-2, 334 had been diagnosed with invasive primary cancer from 1 month to 42 years before HUNT-2 according to CRN and self-report. An overall random sample of controls without cancer five times larger than the sample of cases (N = 1,670) were drawn from the parent cohort.</p> <p>Results</p> <p>The cancer sample comprised 128 STS and 206 LTS. For most variables no significant differences were observed between LTS and STS. LTS were significantly more women, and cases with gynaecological cancer, with physical impairment and more thyroid diseases compared to STS. When comparing all the survivors with controls, the survivors showed significantly higher rate of pensioning, decreased self-rated health, more physical impairment and thyroid diseases, daily use of medication and psychotropics and higher level of anxiety and Framingham Risk score. Multivariate logistic regression analysis showed that increasing age, being female, physical impairment and thyroid diseases all were significantly associated with being survivor versus controls.</p> <p>Conclusion</p> <p>STS and LTS showed mostly similar situation. Compared to controls, the survivors reported somewhat poorer physical and mental health, but these differences were of doubtful clinical significance.</p

The Importance of Incorporating At-Home Testing Into SARS-CoV-2 Point Prevalence Estimates: Findings From a US National Cohort, February 2022

Background: Passive, case-based surveillance underestimates the true extent of active infections in the population due to undiagnosed and untested cases, the exclusion of probable cases diagnosed point-of-care rapid antigen tests, and the exclusive use of at-home rapid tests which are not reported as part of case-based surveillance. The extent in which COVID-19 surveillance may be underestimating the burden of infection is likely due to time-varying factors such as decreased test-seeking behaviors and increased access to and availability of at-home testing. Objective: The objective of this study is to estimate the prevalence of SARS-CoV-2 based on different definitions of a case to ascertain the extent to which cases of SARS-CoV-2 may be underestimated by case-based surveillance. Methods: A survey on COVID-19 exposure, infection, and testing was administered to calculate point prevalence of SARS-CoV-2 among a diverse sample of cohort adults from February 8, 2022, to February 22, 2022. Three-point prevalence estimates were calculated among the cohort, as follows: (1) proportion positives based on polymerase chain reaction (PCR) and rapid antigen tests; (2) proportion positives based on testing exclusively with rapid at-home tests; and (3) proportion of probable undiagnosed cases. Test positivity and prevalence differences across booster status were also examined. Results: Among a cohort of 4328, there were a total of 644 (14.9%) cases. The point prevalence estimate based on PCR or rapid antigen tests was 5.5% (95% CI 4.8%-6.2%), 3.7% (95% CI 3.1%-4.2%) based on at-home rapid tests, and 5.7% (95% CI 5.0%-6.4%) based on the case definition of a probable case. The total point prevalence across all definitions was 14.9% (95% CI 13.8%-16.0%). The percent positivity among PCR or rapid tests was 50.2%. No statistically significant differences were observed in prevalence between participants with a COVID-19 booster compared to fully vaccinated and nonboosted participants except among exclusive at-home rapid testers. Conclusions: Our findings suggest a substantial number of cases were missed by case-based surveillance systems during the Omicron B.1.1.529 surge, when at-home testing was common. Point prevalence surveys may be a rapid tool to be used to understand SARS-CoV-2 prevalence and would be especially important during case surges to measure the scope and spread of active infections in the population

Serosorting Is Associated with a Decreased Risk of HIV Seroconversion in the EXPLORE Study Cohort

Background: Seroadaptation strategies such as serosorting and seropositioning originated within communities of men who have sex with men (MSM), but there are limited data about their effectiveness in preventing HIV transmission when utilized by HIV-negative men. Methodology/Principal Findings: Data from the EXPLORE cohort of HIV-negative MSM who reported both seroconcordant and serodiscordant partners were used to evaluate serosorting and seropositioning. The association of serosorting and seropositioning with HIV seroconversion was evaluated in this cohort of high risk MSM from six U.S. cities. Serosorting was independently associated with a small decrease in risk of HIV seroconversion (OR = 0.88; 95%CI, 0.81–0.95), even among participants reporting $10 partners. Those who more consistently practiced serosorting were more likely to be white (p = 0.01), have completed college (p =,0.0002) and to have had 10 or more partners in the six months before the baseline visit (p = 0.01) but did not differ in age, reporting HIV-infected partners, or drug use. There was no evidence of a seroconversion effect with seropositioning (OR 1.02, 95%CI, 0.92–1.14). Significance: In high risk HIV uninfected MSM who report unprotected anal intercourse with both seroconcordant and serodiscordant partners, serosorting was associated with a modest decreased risk of HIV infection. To maximize any potential benefit, it will be important to increase accurate knowledge of HIV status, through increased testing frequency

Patient-reported outcome measures for cancer caregivers: a systematic review

Purpose Informal caregivers provide invaluable help and support to people with cancer. As treatments extend survival and the potential burdens on carers increase, there is a need to assess the impact of the role. This systematic review identified instruments that measure the impact of caregiving, evaluated their psychometric performance specifically in cancer and appraised the content. Methods A 2-stage search strategy was employed to: 1. identify instruments that measure the impact of caregiving, 2. run individual searches on each measure to identify publications evaluating psychometric performance in the target population. Searches were conducted in Medline, Embase, CINAHL and Psychinfo and restricted to English for instrument used and article language. Psychometric performance was evaluated for content and construct validity, internal consistency, test-retest reliability, precision, responsiveness and acceptability. Individual scale items were extracted and systematically categorised into conceptual domains. Results 10 papers were included reporting on the psychometric properties of 8 measures. Although construct validity and internal consistency were most frequently evaluated, no study comprehensively evaluated all relevant properties. Few studies met our inclusion criteria so it was not possible to consider the psychometric performance of the measures across a group of studies. Content analysis resulted in 16 domains with 5 overarching themes: lifestyle disruption; wellbeing; health of the caregiver; managing the situation and relationships. Conclusions Few measures of caregiver impact have been subject to psychometric evaluation in cancer caregivers. Those that have do not capture well changes in roles and responsibilities within the family and career, indicating the need for a new instrument