Resolving the genealogy of life-the phylogenetic relationships that describe the evolutionary history of species-remains one of the great challenges of systematic biology. The recent proliferation of ...DNA sequencing technologies has sparked a rapid increase in the volume of genetic data being applied to phylogenetic studies. Single nucleotide polymorphism (SNP) data, ubiquitous genetic markers once considered reserved for population genetic studies, are now being applied in phylogenetics research at deep evolutionary timescales. The potential for SNPs to resolve contentious phylogenetic problems while researchers also investigate population demographics is promising, yet serious challenges remain with respect to data collection, assembly, modeling, and analysis. The low cost and ease of collecting SNPs suggest that they will remain an important source of genetic information for inferring phylogenies across time periods ranging from the Anthropocene to the Cretaceous.
The Issue: Coronavirus-19 (COVID-19) is transforming every aspect of our lives. Identified in late 2019, COVID-19 quickly became characterized as a global pandemic by March of 2020. Given the rapid ...acceleration of transmission, and the lack of preparedness to prevent and treat this virus, the negative impacts of COVID-19 are rippling through every facet of society. Although large numbers of people throughout the world will show resilience to the profound loss, stress, and fear associated with COVID-19, the virus will likely exacerbate existing mental health disorders and contribute to the onset of new stress-related disorders for many. Recommendations: The field of traumatic stress should address the serious needs that will emerge now and well into the future. However, we propose that these efforts may be limited, in part, by ongoing gaps that exist within our research and clinical care. In particular, we suggest that COVID-19 requires us to prioritize and mobilize as a research and clinical community around several key areas: (a) diagnostics, (b) prevention, (c) public outreach and communication, (d) working with medical staff and mainstreaming into nonmental health services, and (e) COVID-19-specific trauma research. As members of our community begin to rapidly develop and test interventions for COVID-19-related distress, we hope that those in positions of leadership in the field of traumatic stress consider limits of our current approaches, and invest the intellectual and financial resources urgently needed in order to innovate, forge partnerships, and develop the technologies to support those in greatest need.
Clinical Impact Statement
The novel coronavirus-19 (COVID-19) has rapidly emerged as a global pandemic placing unpresented stress on all aspects of society. The virus is likely to exacerbate and increase stress-related disorders for many throughout the world. Although those in the field of traumatic stress can play an important role in the immediate and long-term response to COVID-19, existing gaps in research and clinical care may limit our efficacy. We propose that there is an urgent need to reduce critical gaps in several key areas as we confront this unprecedented challenge and develop novel methods for empowering communities and supporting those in greatest need.
This paper applies the Least Absolute Shrinkage and Selection Operator (LASSO) to make rolling one-minute-ahead return forecasts using the entire cross-section of lagged returns as candidate ...predictors. The LASSO increases both out-of-sample fit and forecast-implied Sharpe ratios. This out-of-sample success comes from identifying predictors that are unexpected, short-lived, and sparse. Although the LASSO uses a statistical rule rather than economic intuition to identiy predictors, the predictors it identifies are nevertheless associated with economically meaningful events: the LASSO tends to identify as predictors stocks with news about fundamentals.
Genealogical data are an important source of evidence for delimiting species, yet few statistical methods are available for calculating the probabilities associated with different species ...delimitations. Bayesian species delimitation uses reversible-jump Markov chain Monte Carlo (rjMCMC) in conjunction with a user-specified guide tree to estimate the posterior distribution for species delimitation models containing different numbers of species. We apply Bayesian species delimitation to investigate the speciation history of forest geckos (Hemidactylus fasciatus) from tropical West Africa using five nuclear loci (and mtDNA) for 51 specimens representing 10 populations. We find that species diversity in H. fasciatus is currently underestimated, and describe three new species to reflect the most conservative estimate for the number of species in this complex. We examine the impact of the guide tree, and the prior distributions on ancestral population sizes (θ) and root age (τ0), on the posterior probabilities for species delimitation. Mis-specification of the guide tree or the prior distribution for θ can result in strong support for models containing more species. We describe a new statistic for summarizing the posterior distribution of species delimitation models, called speciation probabilities, which summarize the posterior support for each speciation event on the starting guide tree.
The Spectre of Too Many Species Leaché, Adam D.; Zhu, Tianqi; Rannala, Bruce ...
Systematic biology,
01/2019, Letnik:
68, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Recent simulation studies examining the performance of Bayesian species delimitation as implemented in the BPP program have suggested that BPP may detect population splits but not species divergences ...and that it tends to over-split when data of many loci are analyzed. Here, we confirm these results and provide the mathematical justifications. We point out that the distinction between population and species splits made in the protracted speciation model (PSM) has no influence on the generation of gene trees and sequence data, which explains why no method can use such data to distinguish between population splits and speciation. We suggest that the PSM is unrealistic as its mechanism for assigning species status assumes instantaneous speciation, contradicting prevailing taxonomic practice. We confirm the suggestion, based on simulation, that in the case of speciation with gene flow, Bayesian model selection as implemented in BPP tends to detect population splits when the amount of data (the number of loci) increases. We discuss the use of a recently proposed empirical genealogical divergence index (gdi) for species delimitation and illustrate that parameter estimates produced by a full likelihood analysis as implemented in BPP provide much more reliable inference under the gdi than the approximate method PHRAPL. We distinguish between Bayesian model selection and parameter estimation and suggest that the model selection approach is useful for identifying sympatric cryptic species, while the parameter estimation approach may be used to implement empirical criteria for determining species status among allopatric populations.
Happiness and other emotions spread between people in direct contact, but it is unclear whether massive online social networks also contribute to this spread. Here, we elaborate a novel method for ...measuring the contagion of emotional expression. With data from millions of Facebook users, we show that rainfall directly influences the emotional content of their status messages, and it also affects the status messages of friends in other cities who are not experiencing rainfall. For every one person affected directly, rainfall alters the emotional expression of about one to two other people, suggesting that online social networks may magnify the intensity of global emotional synchrony.
The production of animal-based foods is associated with higher greenhouse gas (GHG) emissions than plant-based foods. The objective of this study was to estimate the difference in dietary GHG ...emissions between self-selected meat-eaters, fish-eaters, vegetarians and vegans in the UK. Subjects were participants in the EPIC-Oxford cohort study. The diets of 2,041 vegans, 15,751 vegetarians, 8,123 fish-eaters and 29,589 meat-eaters aged 20–79 were assessed using a validated food frequency questionnaire. Comparable GHG emissions parameters were developed for the underlying food codes using a dataset of GHG emissions for 94 food commodities in the UK, with a weighting for the global warming potential of each component gas. The average GHG emissions associated with a standard 2,000 kcal diet were estimated for all subjects. ANOVA was used to estimate average dietary GHG emissions by diet group adjusted for sex and age. The age-and-sex-adjusted mean (95 % confidence interval) GHG emissions in kilograms of carbon dioxide equivalents per day (kgCO₂e/day) were 7.19 (7.16, 7.22) for high meat-eaters ( > = 100 g/d), 5.63 (5.61, 5.65) for medium meat-eaters (50-99 g/d), 4.67 (4.65, 4.70) for low meat-eaters ( < 50 g/d), 3.91 (3.88, 3.94) for fish-eaters, 3.81 (3.79, 3.83) for vegetarians and 2.89 (2.83, 2.94) for vegans. In conclusion, dietary GHG emissions in self-selected meat-eaters are approximately twice as high as those in vegans. It is likely that reductions in meat consumption would lead to reductions in dietary GHG emissions.
Human behaviour is thought to spread through face-to-face social networks, but it is difficult to identify social influence effects in observational studies, and it is unknown whether online social ...networks operate in the same way. Here we report results from a randomized controlled trial of political mobilization messages delivered to 61 million Facebook users during the 2010 US congressional elections. The results show that the messages directly influenced political self-expression, information seeking and real-world voting behaviour of millions of people. Furthermore, the messages not only influenced the users who received them but also the users' friends, and friends of friends. The effect of social transmission on real-world voting was greater than the direct effect of the messages themselves, and nearly all the transmission occurred between 'close friends' who were more likely to have a face-to-face relationship. These results suggest that strong ties are instrumental for spreading both online and real-world behaviour in human social networks.
Health care costs make up nearly a fifth of U.S. gross domestic product, but health care is a peculiar thing to buy and sell. Both a scarce resource and a basic need, it involves physical and ...emotional vulnerability and at the same time it operates as big business. Patients have little choice but to trust those who provide them care, but even those providers confront a great deal of medical uncertainty about the services they offer.Selling Our Soulslooks at the contradictions inherent in one particular health care market-hospital care. Based on extensive interviews and observations across the three hospitals of one California city, the book explores the tensions embedded in the market for hospital care, how different hospitals manage these tensions, the historical trajectories driving disparities in contemporary hospital practice, and the perils and possibilities of various models of care.
As Adam Reich shows, the book's three featured hospitals could not be more different in background or contemporary practice. PubliCare was founded in the late nineteenth century as an almshouse in order to address the needs of the destitute. HolyCare was founded by an order of nuns in the mid-twentieth century, offering spiritual comfort to the paying patient. And GroupCare was founded in the late twentieth century to rationalize and economize care for middle-class patients and their employers. Reich explains how these legacies play out today in terms of the hospitals' different responses to similar market pressures, and the varieties of care that result.
Selling Our Soulsis an in-depth investigation into how hospital organizations and the people who work in them make sense of and respond to the modern health care market.
PDF
