経済における因果性の探索

2018年度第4回研究集会[2018年12月6日(木)]報告要

Sexualized drug use ("chemsex') and high-risk sexual behaviours in HIV-positive men who have sex with men

Objectives The incidence of sexually transmitted infections (STI s) and HIV infection remains high in gay, bisexual, and other men who have sex with men (MSM ) in the UK , and sexualized drug use (“chemsex”) and injecting drug use (“slamsex”) may play a part in this. We aimed to characterize HIV ‐positive MSM engaging in chemsex/slamsex and to assess the associations with self‐reported STI diagnoses and sexual behaviours. Methods Data from a 2014 survey of people attending HIV clinics in England and Wales were linked to clinical data from national HIV surveillance records and weighted to be nationally representative. Multivariable logistic regression assessed the associations of chemsex and slamsex with self‐reported unprotected anal intercourse (UAI ), serodiscordant UAI (sdUAI ) (i.e. UAI with an HIV ‐negative or unknown HIV status partner), sdUAI with a detectable viral load (>50 HIV ‐1 RNA copies/mL ), hepatitis C, and bacterial STI s. Results In the previous year, 29.5% of 392 sexually active participants engaged in chemsex, and 10.1% in slamsex. Chemsex was significantly associated with increased odds of UAI [adjusted odds ratio (AOR ) 5.73; P < 0.001], sdUAI (AOR 2.34; P < 0.05), sdUAI with a detectable viral load (AOR 3.86; P < 0.01), hepatitis C (AOR 6.58; P < 0.01), and bacterial STI diagnosis (AOR 2.65; P < 0.01). Slamsex was associated with increased odds of UAI (AOR 6.11; P < 0.05), hepatitis C (AOR 9.39; P < 0.001), and bacterial STI diagnosis (AOR 6.11; P < 0.001). Conclusions Three in ten sexually active HIV ‐positive MSM engaged in chemsex in the past year, which was positively associated with self‐reported depression/anxiety, smoking, nonsexual drug use, risky sexual behaviours, STI s, and hepatitis C. Chemsex may therefore play a role in the ongoing HIV and STI epidemics in the UK

Zika Virus Infection as a Cause of Congenital Brain Abnormalities and Guillain-Barré Syndrome: Systematic Review.

BACKGROUND The World Health Organization (WHO) stated in March 2016 that there was scientific consensus that the mosquito-borne Zika virus was a cause of the neurological disorder Guillain-Barré syndrome (GBS) and of microcephaly and other congenital brain abnormalities based on rapid evidence assessments. Decisions about causality require systematic assessment to guide public health actions. The objectives of this study were to update and reassess the evidence for causality through a rapid and systematic review about links between Zika virus infection and (a) congenital brain abnormalities, including microcephaly, in the foetuses and offspring of pregnant women and (b) GBS in any population, and to describe the process and outcomes of an expert assessment of the evidence about causality. METHODS AND FINDINGS The study had three linked components. First, in February 2016, we developed a causality framework that defined questions about the relationship between Zika virus infection and each of the two clinical outcomes in ten dimensions: temporality, biological plausibility, strength of association, alternative explanations, cessation, dose-response relationship, animal experiments, analogy, specificity, and consistency. Second, we did a systematic review (protocol number CRD42016036693). We searched multiple online sources up to May 30, 2016 to find studies that directly addressed either outcome and any causality dimension, used methods to expedite study selection, data extraction, and quality assessment, and summarised evidence descriptively. Third, WHO convened a multidisciplinary panel of experts who assessed the review findings and reached consensus statements to update the WHO position on causality. We found 1,091 unique items up to May 30, 2016. For congenital brain abnormalities, including microcephaly, we included 72 items; for eight of ten causality dimensions (all except dose-response relationship and specificity), we found that more than half the relevant studies supported a causal association with Zika virus infection. For GBS, we included 36 items, of which more than half the relevant studies supported a causal association in seven of ten dimensions (all except dose-response relationship, specificity, and animal experimental evidence). Articles identified nonsystematically from May 30 to July 29, 2016 strengthened the review findings. The expert panel concluded that (a) the most likely explanation of available evidence from outbreaks of Zika virus infection and clusters of microcephaly is that Zika virus infection during pregnancy is a cause of congenital brain abnormalities including microcephaly, and (b) the most likely explanation of available evidence from outbreaks of Zika virus infection and GBS is that Zika virus infection is a trigger of GBS. The expert panel recognised that Zika virus alone may not be sufficient to cause either congenital brain abnormalities or GBS but agreed that the evidence was sufficient to recommend increased public health measures. Weaknesses are the limited assessment of the role of dengue virus and other possible cofactors, the small number of comparative epidemiological studies, and the difficulty in keeping the review up to date with the pace of publication of new research. CONCLUSIONS Rapid and systematic reviews with frequent updating and open dissemination are now needed both for appraisal of the evidence about Zika virus infection and for the next public health threats that will emerge. This systematic review found sufficient evidence to say that Zika virus is a cause of congenital abnormalities and is a trigger of GBS

Subjectify or die! On the evolution of the causal pair car-parce que

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PHYSICAL CONSTRAINTS ON CAUSALITY-VIOLATING SPACETIMES IN GENERAL RELATIVITY

in General Relativity. (Under the direction of Arkady Kheyfets.) The theoretical possibility of global causality violation has long been a problem within general relativity, for there exists a large number of model spacetimes known to admit closed time-like curves, trajectories allowing a timelike observer to return to some point in her own past. However, nearly all such known models have some unphysical feature. These physicality issues rendered causality-violation to the status of an interesting but safely theoretical problem until twenty years ago, when the appearance of a new type of causality-violating model spacetime and the subsequent proliferation of new models admitting closed timelike curves forced the attention of the community to the issue, and made causality violation and its possible physical consequences an active area of research within general relativity. This paper focuses on some of the older causality-violating spacetimes which model matter sources with cylindrical symme-try. By describing how cylindrically-symmetric solutions can be embedded within a spatially bounded and physically realistic body which outwardly has the symmetry of a torus or ring, it is shown that the chief problem of physical plausibility which these older solutions possess can be resolved. The intention is to make these models active candidates for consideration i

The Affordance Competition Hypothesis: making decisions with motor structures

Human modern life entails the need to make many abstract, deliberative decisions such as selecting a career or buying a house. This fact prompted the development of theories suggesting that decisions are made within a cognitive system prior to being relayed to the motor system for outputting the desired action: a serial architecture of sensing, thinking, and finally acting. However, the human brain is the product of a long evolution during which animals had to face challenges very different from our modern-life decisions. Most decisions in the animal realm must be made in real-time to cope with urgent priorities in dynamically changing environments: here, there is no time for carefully thinking before acting. A recent theoretical framework has proposed that for effective behavior in such environments, the brain uses a parallel architecture in which multiple potential actions can be specified simultaneously, and one is selected on the basis of current sensory information. This is called the affordance competition hypothesis. According to this theory, decisions emerge from a consensus arising in a distributed brain network, especially involving sensorimotor structures. In this presentation, I will describe the work I have been conducting for the six last years as a postdoctoral researcher at the Cognition and Actions lab of the Institute of Neuroscience in Brussels (UCL). My current projects aim at better understanding how the human brain computes action-based decisions. A first project focused on the contribution of the primary motor cortex to reinforcement learning and decision-making. A second project explored the cortical correlates of spatial attention and action selection during motor decisions. Finally, a third project investigated the motor cortical signatures of urgency during dynamic decision-making. Altogether, they involved a combination of techniques including continuous theta burst stimulation, single-pulse transcranial magnetic stimulation, electroencephalography and various data analysis approaches (e.g., Monte-Carlo permutations on EEG data, and computational modelling of behavioral data) which I will introduce throughout my presentation