Combinatorial simplex algorithms can solve mean payoff games

A combinatorial simplex algorithm is an instance of the simplex method in which the pivoting depends on combinatorial data only. We show that any algorithm of this kind admits a tropical analogue which can be used to solve mean payoff games. Moreover, any combinatorial simplex algorithm with a strongly polynomial complexity (the existence of such an algorithm is open) would provide in this way a strongly polynomial algorithm solving mean payoff games. Mean payoff games are known to be in NP and co-NP; whether they can be solved in polynomial time is an open problem. Our algorithm relies on a tropical implementation of the simplex method over a real closed field of Hahn series. One of the key ingredients is a new scheme for symbolic perturbation which allows us to lift an arbitrary mean payoff game instance into a non-degenerate linear program over Hahn series.Comment: v1: 15 pages, 3 figures; v2: improved presentation, introduction expanded, 18 pages, 3 figure

Modeling approach to regime shifts of primary production in shallow coastal ecosystems

Pristine coastal shallow systems are usually dominated by extensive meadows of seagrass species, which are assumed to take advantage of nutrient supply from sediment. An increasing nutrient input is thought to favour phytoplankton, epiphytic microalgae, as well as opportunistic ephemeral macroalgae that coexist with seagrasses. The primary cause of shifts and succession in the macrophyte community is the increase of nutrient load to water; however temperature plays also an important role. A competition model between rooted seagrass (Zostera marina), macroalgae (Ulva sp), and phytoplankton has been developed to analyse the succession of primary producer communities in these systems. Successions of dominance states, with different resilience characteristics, are found when modifying the input of nutrients and the seasonal temperature and light intensity forcing.Comment: 33 pages, including 10 figures. To appear in Ecological Complexit

Objectively measured sedentary time, physical activity and kidney function in people with recently diagnosed Type 2 diabetes: a prospective cohort analysis.

AIM: To assess the prospective association between objectively measured physical activity and kidney function over 4 years in people with Type 2 diabetes. METHODS: Individuals (120 women and 206 men) participating in the ADDITION-Plus trial underwent assessment of sedentary time (SED-time), time spent in moderate-to-vigorous-intensity physical activity (MVPA) and total physical activity energy expenditure (PAEE) using a combined heart rate and movement sensor, and kidney function [estimated glomerular filtration rate (eGFR), serum creatinine and urine albumin-to-creatinine ratio (ACR)] at baseline and after 4 years of follow-up. Multivariate regression was used to quantify the association between change in SED-time, MVPA and PAEE and kidney measures at four-year follow-up, adjusting for change in current smoking status, waist circumference, HbA1c , systolic blood pressure, triglycerides and medication usage. RESULTS: Over 4 years, there was a decline in eGFR values from 87.3 to 81.7 ml/min/1.73m(2) (P < 0.001); the prevalence of reduced eGFR (eGFR < 60 ml/min/1.73m(2) ) increased from 6.1 to 13.2% (P < 0.001). There were small increases in serum creatinine (median: 81-84 μmol/l, P < 0.001) and urine ACR (median: 0.9-1.0 mg/mmol, P = 0.005). Increases in SED-time were associated with increases in serum creatinine after adjustment for MVPA and cardiovascular risk factors (β = 0.013, 95% CI: 0.001, 0.03). Conversely, increases in PAEE were associated with reductions in serum creatinine (β = -0.001, 95% CI: -0.003, -0.0001). CONCLUSION: Reducing time spent sedentary and increasing overall physical activity may offer intervention opportunities to improve kidney function among individuals with diabetes. (Trial Registry no. ISRCTN 99175498).The trial is supported by the Medical Research Council (grant reference no. G0001164), the Wellcome Trust (grant reference no. G061895), National Health Service R&D support funding (including the Primary Care Research and Diabetes Research Networks) and National Institute of Health Research under its Programme Grants for Applied Research scheme (RP-PG-0606-1259). SJG was a member of the NIHR School for Primary Care Research. The Primary Care Unit is supported by NIHR Research funds. The views expressed in this publication are those of the authors and not necessarily those of the National Health Service, the NIHR, or the UK Department of Health. VYG was supported by Global Scholarship Programme for Research Excellence-CNOOC grant from the Chinese University of Hong Kong.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/dme.1288

Twenty-five new viruses associated with the drosophilidae (Diptera)

Drosophila melanogaster is an important laboratory model for studies of antiviral immunity in invertebrates, and Drosophila species provide a valuable system to study virus host range and host switching. Here, we use metagenomic RNA sequencing of about 1600 adult flies to discover 25 new RNA viruses associated with six different drosophilid hosts in the wild. We also provide a comprehensive listing of viruses previously reported from the Drosophilidae. The new viruses include Iflaviruses, Rhabdoviruses, Nodaviruses, and Reoviruses, and members of unclassified lineages distantly related to Negeviruses, Sobemoviruses, Poleroviruses, Flaviviridae, and Tombusviridae. Among these are close relatives of Drosophila X virus and Flock House virus, which we find in association with wild Drosophila immigrans. These two viruses are widely used in experimental studies but have not been previously reported to naturally infect Drosophila. Although we detect no new DNA viruses, in D. immigrans and Drosophila obscura, we identify sequences very closely related to Armadillidium vulgare iridescent virus (Invertebrate iridescent virus 31), bringing the total number of DNA viruses found in the Drosophilidae to three.This work was funded by a Wellcome Trust Research Career Development Fellowship (WT085064) to DJO. BL was supported by grants from the UK Natural Environment Research Council (NE/L004232/1) and the European Research Council (281668, Drosophila Infection). SHL was supported by a Natural Environment Research Council Doctoral Training Grant (NERC DG NE/J500021/1). Work in DJO’s laboratory is partly supported by a Wellcome Trust strategic award to the Centre for Immunity, Infection and Evolution (WT095831). The authors confirm that the funder had no influence over the study design, content of the article, or selection of this journal

U.S. adolescent and adult women\u27s experiences accessing and using toilets in schools, workplaces, and public spaces: A multi-site focus group study to inform future research in bladder health

The World Health Organization recognizes access to clean and safe toilets as crucial for public health. This study explored U.S. adolescent and adult cisgender women\u27s lived experiences accessing toilets in schools, workplaces, and public spaces. As part of the Prevention of Lower Urinary Tract Symptoms (PLUS) Research Consortium, we conducted 44 focus groups with female participants (n = 360; ages 11-93). Focus groups were stratified by age (11-14, 15-17, 18-25, 26-44, 45-64, 65+) and conducted across 7 geographically diverse U.S. sites from July 2017-April 2018. Using a transdisciplinary approach, we conducted conventional qualitative coding informed by our PLUS conceptual framework and used content analysis processes to identify salient themes. Across settings, toilet access was restricted by gatekeepers (i.e., individuals who control access to toilets). In contrast, self-restricting toilet use (deciding not to use the toilet despite biologic need to urinate) was based on internalized norms to prioritize school and job responsibilities over urination. In public spaces, self-restricting use was largely in response to lack of cleanliness. Across the life course, participants perceived gender disparities in the ability to easily access public toilets. Further research is needed to determine if and how these factors impact bladder health across the life course

Evaluation of Dynamic Models of Distillation Columns with Emphasis on the Initial Response

The flow dynamics (tray hydraulics) are of key importance for the initial dynamic response of distillation columns. The most important parameters are the liquid holdup, the liquid hydraulic time constant and the vapor constant representing the initial effect of a change in vapor flow on liquid flow. In the paper we present methods for determining these parameters experimentally, and compare the results with estimates from available correlations such as the Francis Weir formula

Designing theoretically-informed implementation interventions: Fine in theory, but evidence of effectiveness in practice is needed

The Improved Clinical Effectiveness through Behavioural Research Group (ICEBeRG) authors assert that a key weakness in implementation research is the unknown applicability of a given intervention outside its original site and problem, and suggest that use of explicit theory offers an effective solution. This assertion is problematic for three primary reasons. First, the presence of an underlying theory does not necessarily ease the task of judging the applicability of a piece of empirical evidence. Second, it is not clear how to translate theory reliably into intervention design, which undoubtedly involves the diluting effect of "common sense." Thirdly, there are many theories, formal and informal, and it is not clear why any one should be given primacy. To determine whether explicitly theory-based interventions are, on average, more effective than those based on implicit theories, pragmatic trials are needed. Until empirical evidence is available showing the superiority of theory-based interventions, the use of theory should not be used as a basis for assessing the value of implementation studies by research funders, ethics committees, editors or policy decision makers

‘‘You try to keep a brave face on but inside you are in bits’’: Grandparent experiences of engaging with professionals in Children’s Services

This article presents findings from an evaluation conducted in 2012, of the advice and advocacy service provided by the charity Family Rights Group for families involved with children’s services. It specifically focuses on the experiences of grandparents and explores accounts from grandparents who were either in the process of seeking care of their grandchildren or were already caring for grandchildren but without formal support or recognition. The findings suggest that there is a need to pay greater attention to the fears of such grandparents about children’s services in a context where there appears to be a policy preference for adoption. Also evident is a paradox at the heart of contemporary social work practices towards grandparents. While some felt dismissed and marginalized very quickly by social workers and imaginative approaches to care possibilities did not appear to be pursued, others were carrying enormous burdens of care often for very long periods of time without either financial support or legal recognition. To strengthen the care options for children and respect the ethic of care that is clearly to be observed operating in grandparenting practices, it is suggested that a more thorough interrogation of the multiple and often highly contradictory meanings attached to family is required on the part of social workers

Converging on bladder health through design thinking: From an ecology of influence to a focused set of research questions

Lower urinary tract symptoms affect a substantial number of women in the United States (U.S.) and globally. In 2015, the Prevention of Lower Urinary tract Symptoms in women (PLUS) Research Consortium was funded to establish the scientific basis for prevention efforts by (1) understanding healthy bladder function and (2) identifying risk and protective factors for bladder health in women across the lifecourse. This transdisciplinary consortium generated a list of over 600 candidate risk and protective factors for bladder health in women and girls and refined and prioritized these into 29 focused research questions to inform a national longitudinal observational study in the U.S. This paper describes that process using design thinking, a human-centered set of principles and strategies by which innovations are developed, as a framework. Design thinking is an iterative process consisting of five stages: Empathizing with end-users of innovations, Defining core principles girding the work, Ideation of all possible solutions, and rapid-cycle Prototyping and Testing of solutions. Lessons learned are offered to inform future prevention science research endeavors that might benefit from such an approach