LP-based Covering Games with Low Price of Anarchy

We present a new class of vertex cover and set cover games. The price of anarchy bounds match the best known constant factor approximation guarantees for the centralized optimization problems for linear and also for submodular costs -- in contrast to all previously studied covering games, where the price of anarchy cannot be bounded by a constant (e.g. [6, 7, 11, 5, 2]). In particular, we describe a vertex cover game with a price of anarchy of 2. The rules of the games capture the structure of the linear programming relaxations of the underlying optimization problems, and our bounds are established by analyzing these relaxations. Furthermore, for linear costs we exhibit linear time best response dynamics that converge to these almost optimal Nash equilibria. These dynamics mimic the classical greedy approximation algorithm of Bar-Yehuda and Even [3]

Mental health outcomes after SARS-CoV-2 vaccination in the United States: A national cross-sectional study.

Funder: NIHR Cambridge Biomedical Research CentreFunder: National Institute for Health Research (NIHR)BACKGROUND: Worsening of anxiety and depressive symptoms have been widely described during the COVID-19 pandemic. It can be hypothesized that vaccination could link to reduced symptoms of anxiety and/or depression. However, to date, no study has assessed this. This study aims to examine anxiety and depressive symptoms after vaccination in US adults, meanwhile test sociodemographic disparities in these outcomes. METHODS: Data from the January 6-June 7 2021, cross-sectional Household Pulse Survey were analyzed. Using survey-weighted logistic regression, we assessed the relationships between SARS-CoV-2 vaccination and anxiety and/or depressive symptoms, both on overall and sociodemographic subgroups. We controlled for a variety of potential socioeconomic and demographic confounding factors. RESULTS: Of the 453,167 participants studied, 52.2% of the participants had received the COVID-19 vaccine, and 26.5% and 20.3% of the participants reported anxiety and depression, respectively. Compared to those not vaccinated, the vaccinated participants had a 13% lower odds of anxiety (adjusted odds ratio [AOR] = 0.85, 95%CI 0.83-0.90) and 17% lower odds of depression (AOR = 0.83, 95%CI 0.79-0.85). Disparities on the above associations were identified in age, marital status, education level, ethnic/race, and income level, but not on gender. LIMITATIONS: The causal inference was not able to be investigated due to the cross-sectional study design. CONCLUSION: Being vaccinated for SARS-CoV-2 was associated with lower odds of anxiety and/or depressive symptoms. While those more middle-aged or more affluent, were more likely to show these negative associations, the contrary was observed in ethnic minorities and those with lower educational attainment. More strategic and demography-sensitive public health communications could perhaps temper these issues

Longer-term mortality following SARS-CoV-2 infection in people with severe mental illness: retrospective case-matched study.

Persisting symptoms and dysfunction after SARS-CoV-2 infection have frequently been observed. However, information on the aftermath of COVID-19 is inadequate. We followed up people with severe mental illness (SMI) infected with SARS-CoV-2, and evaluated their longer-term mortality, using data from Cambridgeshire and Peterborough NHS Foundation Trust, UK. We examined the time course and duration of mortality risk from the point of diagnosis. After SARS-CoV-2 infection, people with SMI had a substantially higher risk of death (hazard ratio (HR) = 5.16, 95% confidence interval (CI) 1.56-17.03; P = 0.007) during the first 28 days and during the following 28-60 days (HR = 2.96, 95% CI 1.21-7.26; P = 0.018) than those without infection, but after 60 days the additional risk of death was no longer significant (HR = 2.33, 95% CI 0.83-6.53; P = 0.107)

Biodiversity Informatics: An interactive computer- aided identification and knowledge base on tree species of Lao PDR

International audienceObjectives • To enrich the existing knowledge base (BIOTIK project*) on a major "hot spot" of biodiversity: the rain forests of Annamite Mountain range of Lao PDR, in the framework of the Inventory of biodiversity of forest canopies conducted in 2012 in Lao PDR under F. Hallé scientific direction, and also to participate to broader initiatives such as Pl@ntNet project**. • To translate the identification tool in the Lao language in order to contribute to the capacity-building in plant taxonomy in the country. • To transfer the identification system to touch pads, enabling plant identification and entering data directly in the field

Impairments in reinforcement learning do not explain enhanced habit formation in cocaine use disorder

Abstract: Rationale: Drug addiction has been suggested to develop through drug-induced changes in learning and memory processes. Whilst the initiation of drug use is typically goal-directed and hedonically motivated, over time, drug-taking may develop into a stimulus-driven habit, characterised by persistent use of the drug irrespective of the consequences. Converging lines of evidence suggest that stimulant drugs facilitate the transition of goal-directed into habitual drug-taking, but their contribution to goal-directed learning is less clear. Computational modelling may provide an elegant means for elucidating changes during instrumental learning that may explain enhanced habit formation. Objectives: We used formal reinforcement learning algorithms to deconstruct the process of appetitive instrumental learning and to explore potential associations between goal-directed and habitual actions in patients with cocaine use disorder (CUD). Methods: We re-analysed appetitive instrumental learning data in 55 healthy control volunteers and 70 CUD patients by applying a reinforcement learning model within a hierarchical Bayesian framework. We used a regression model to determine the influence of learning parameters and variations in brain structure on subsequent habit formation. Results: Poor instrumental learning performance in CUD patients was largely determined by difficulties with learning from feedback, as reflected by a significantly reduced learning rate. Subsequent formation of habitual response patterns was partly explained by group status and individual variation in reinforcement sensitivity. White matter integrity within goal-directed networks was only associated with performance parameters in controls but not in CUD patients. Conclusions: Our data indicate that impairments in reinforcement learning are insufficient to account for enhanced habitual responding in CUD

James Hutton’s geological tours of Scotland : romanticism, literary strategies, and the scientific quest

This article explores a somewhat neglected part of the story of the emergence of geology as a science and discourse in the late eighteenth century – James Hutton’s posthumously published accounts of the geological tours of Scotland that he undertook in the years 1785 to 1788 in search of empirical evidence in support of his theory of the Earth and that he intended to include in the projected third volume of his Theory of the Earth of 1795. The article brings some of the assumptions and techniques of literary criticism to bear on Hutton’s scientific travel writing in order to open up new connections between geology, Romantic aesthetics and eighteenth-century travel writing about Scotland. Close analysis of Hutton’s accounts of his field trips to Glen Tilt, Galloway and Arran, supplemented by later accounts of the discoveries at Jedburgh and Siccar Point, reveals the interplay between desire, travel and the scientific quest and foregrounds the textual strategies that Hutton uses to persuade his readers that they share in the experience of geological discovery and interpretation as ‘virtual witnesses’. As well as allowing us to revisit the interrelation between scientific theory and discovery, this article concludes that Hutton was a much better writer than he has been given credit for and suggests that if these geological tours had been published in 1795 they would have made it impossible for critics to dismiss him as an armchair geologist

Evidence for a Long-Lasting Compulsive Alcohol Seeking Phenotype in Rats

Excessive drinking to intoxication is the major behavioral characteristic of those addicted to alcohol but it is not the only one. Indeed, individuals addicted to alcohol also crave alcoholic beverages and spend time and put much effort into compulsively seeking alcohol, before eventually drinking large amounts. Unlike this excessive drinking, for which treatments exist, compulsive alcohol seeking is therefore another key feature of the persistence of alcohol addiction since it leads to relapse and for which there are few effective treatments. Here we provide novel evidence for the existence in rats of an individual vulnerability to switch from controlled to compulsive, punishment-resistant alcohol seeking. Alcohol-preferring rats given access to alcohol under an intermittent 2-bottle choice procedure to establish their alcohol-preferring phenotype were subsequently trained instrumentally to seek and take alcohol on a chained schedule of reinforcement. When stable seeking-taking performance had been established, completion of cycles of seeking responses resulted unpredictably either in punishment (0.45 mA foot-shock) or the opportunity to make a taking response for access to alcohol. Compulsive alcohol seeking, maintained in the face of the risk of punishment, emerged in only a subset of rats with a predisposition to prefer and drink alcohol, and was maintained for almost a year. We show further that a selective and potent μ-opioid receptor antagonist (GSK1521498) reduced both alcohol seeking and alcohol intake in compulsive and non-compulsive rats, indicating its therapeutic potential to promote abstinence and prevent relapse in individuals addicted to alcohol

Association between lithium use and the incidence of dementia and its subtypes: A retrospective cohort study.

BACKGROUND: Dementia is the leading cause of death in elderly Western populations. Preventative interventions that could delay dementia onset even modestly would provide a major public health impact. There are no disease-modifying treatments currently available. Lithium has been proposed as a potential treatment. We assessed the association between lithium use and the incidence of dementia and its subtypes. METHODS AND FINDINGS: We conducted a retrospective cohort study comparing patients treated between January 1, 2005 and December 31, 2019, using data from electronic clinical records of secondary care mental health (MH) services in Cambridgeshire and Peterborough NHS Foundation Trust (CPFT), United Kingdom (catchment area population approximately 0.86 million). Eligible patients were those aged 50 years or over at baseline and who had at least 1 year follow-up, excluding patients with a diagnosis of mild cognitive impairment (MCI) or dementia before, or less than 1 year after, their start date. The intervention was the use of lithium. The main outcomes were dementia and its subtypes, diagnosed and classified according to the International Classification of Diseases-10th Revision (ICD-10). In this cohort, 29,618 patients (of whom 548 were exposed to lithium) were included. Their mean age was 73.9 years. A total of 40.2% were male, 33.3% were married or in a civil partnership, and 71.0% were of white ethnicity. Lithium-exposed patients were more likely to be married, cohabiting or in a civil partnership, to be a current/former smoker, to have used antipsychotics, and to have comorbid depression, mania/bipolar affective disorder (BPAD), hypertension, central vascular disease, diabetes mellitus, or hyperlipidemias. No significant difference between the 2 groups was observed for other characteristics, including age, sex, and alcohol-related disorders. In the exposed cohort, 53 (9.7%) patients were diagnosed with dementia, including 36 (6.8%) with Alzheimer disease (AD) and 13 (2.6%) with vascular dementia (VD). In the unexposed cohort, corresponding numbers were the following: dementia 3,244 (11.2%), AD 2,276 (8.1%), and VD 698 (2.6%). After controlling for sociodemographic factors, smoking status, other medications, other mental comorbidities, and physical comorbidities, lithium use was associated with a lower risk of dementia (hazard ratio [HR] 0.56, 95% confidence interval [CI] 0.40 to 0.78), including AD (HR 0.55, 95% CI 0.37 to 0.82) and VD (HR 0.36, 95% CI 0.19 to 0.69). Lithium appeared protective in short-term (≤1-year exposure) and long-term lithium users (>5-year exposure); a lack of difference for intermediate durations was likely due to lack of power, but there was some evidence for additional benefit with longer exposure durations. The main limitation was the handling of BPAD, the most common reason for lithium prescription but also a risk factor for dementia. This potential confounder would most likely cause an increase in dementia in the exposed group, whereas we found the opposite, and the sensitivity analysis confirmed the primary results. However, the specific nature of the group of patients exposed to lithium means that caution is needed in extending these findings to the general population. Another limitation is that our sample size of patients using lithium was small, reflected in the wide CIs for results relating to some durations of lithium exposure, although again sensitivity analyses remained consistent with our primary findings. CONCLUSIONS: We observed an association between lithium use and a decreased risk of developing dementia. This lends further support to the idea that lithium may be a disease-modifying treatment for dementia and that this is a promising treatment to take forwards to larger randomised controlled trials (RCTs) for this indication

The Medium-Term Impact of COVID-19 Lockdown on Referrals to Secondary Care Mental Health Services: A Controlled Interrupted Time Series Study.

To date, there is a paucity of information regarding the effect of COVID-19 or lockdown on mental disorders. We aimed to quantify the medium-term impact of lockdown on referrals to secondary care mental health clinical services. We conducted a controlled interrupted time series study using data from Cambridgeshire and Peterborough NHS Foundation Trust (CPFT), UK (catchment population ~0.86 million). The UK lockdown resulted in an instantaneous drop in mental health referrals but then a longer-term acceleration in the referral rate (by 1.21 referrals per day per day, 95% confidence interval [CI] 0.41-2.02). This acceleration was primarily for urgent or emergency referrals (acceleration 0.96, CI 0.39-1.54), including referrals to liaison psychiatry (0.68, CI 0.35-1.02) and mental health crisis teams (0.61, CI 0.20-1.02). The acceleration was significant for females (0.56, CI 0.04-1.08), males (0.64, CI 0.05-1.22), working-age adults (0.93, CI 0.42-1.43), people of White ethnicity (0.98, CI 0.32-1.65), those living alone (1.26, CI 0.52-2.00), and those who had pre-existing depression (0.78, CI 0.19-1.38), severe mental illness (0.67, CI 0.19-1.15), hypertension/cardiovascular/cerebrovascular disease (0.56, CI 0.24-0.89), personality disorders (0.32, CI 0.12-0.51), asthma/chronic obstructive pulmonary disease (0.28, CI 0.08-0.49), dyslipidemia (0.26, CI 0.04-0.47), anxiety (0.21, CI 0.08-0.34), substance misuse (0.21, CI 0.08-0.34), or reactions to severe stress (0.17, CI 0.01-0.32). No significant post-lockdown acceleration was observed for children/adolescents, older adults, people of ethnic minorities, married/cohabiting people, and those who had previous/pre-existing dementia, diabetes, cancer, eating disorder, a history of self-harm, or intellectual disability. This evidence may help service planning and policy-making, including preparation for any future lockdown in response to outbreaks