How Gaussian competition leads to lumpy or uniform species distributions

A central model in theoretical ecology considers the competition of a range of species for a broad spectrum of resources. Recent studies have shown that essentially two different outcomes are possible. Either the species surviving competition are more or less uniformly distributed over the resource spectrum, or their distribution is 'lumped' (or 'clumped'), consisting of clusters of species with similar resource use that are separated by gaps in resource space. Which of these outcomes will occur crucially depends on the competition kernel, which reflects the shape of the resource utilization pattern of the competing species. Most models considered in the literature assume a Gaussian competition kernel. This is unfortunate, since predictions based on such a Gaussian assumption are not robust. In fact, Gaussian kernels are a border case scenario, and slight deviations from this function can lead to either uniform or lumped species distributions. Here we illustrate the non-robustness of the Gaussian assumption by simulating different implementations of the standard competition model with constant carrying capacity. In this scenario, lumped species distributions can come about by secondary ecological or evolutionary mechanisms or by details of the numerical implementation of the model. We analyze the origin of this sensitivity and discuss it in the context of recent applications of the model.Comment: 11 pages, 3 figures, revised versio

Mapping the disease-specific LupusQoL to the SF-6D

Purpose To derive a mapping algorithm to predict SF-6D utility scores from the non-preference-based LupusQoL and test the performance of the developed algorithm on a separate independent validation data set. Method LupusQoL and SF-6D data were collected from 320 patients with systemic lupus erythematosus (SLE) attending routine rheumatology outpatient appointments at seven centres in the UK. Ordinary least squares (OLS) regression was used to estimate models of increasing complexity in order to predict individuals’ SF-6D utility scores from their responses to the LupusQoL questionnaire. Model performance was judged on predictive ability through the size and pattern of prediction errors generated. The performance of the selected model was externally validated on an independent data set containing 113 female SLE patients who had again completed both the LupusQoL and SF-36 questionnaires. Results Four of the eight LupusQoL domains (physical health, pain, emotional health, and fatigue) were selected as dependent variables in the final model. Overall model fit was good, with R2 0.7219, MAE 0.0557, and RMSE 0.0706 when applied to the estimation data set, and R2 0.7431, MAE 0.0528, and RMSE 0.0663 when applied to the validation sample. Conclusion This study provides a method by which health state utility values can be estimated from patient responses to the non-preference-based LupusQoL, generalisable beyond the data set upon which it was estimated. Despite concerns over the use of OLS to develop mapping algorithms, we find this method to be suitable in this case due to the normality of the SF-6D data

The porin and the permeating antibiotic: A selective diffusion barrier in gram-negative bacteria

Gram-negative bacteria are responsible for a large proportion of antibiotic resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds, including several classes of antibiotics. Bacterial adaptation to reduce influx through porins is an increasing problem worldwide that contributes, together with efflux systems, to the emergence and dissemination of antibiotic resistance. An exciting challenge is to decipher the genetic and molecular basis of membrane impermeability as a bacterial resistance mechanism. This Review outlines the bacterial response towards antibiotic stress on altered membrane permeability and discusses recent advances in molecular approaches that are improving our knowledge of the physico-chemical parameters that govern the translocation of antibiotics through porin channel

Pleiotropic functions of the tumor- and metastasis-suppressing Matrix Metalloproteinase-8 in mammary cancer in MMTV-PyMT transgenic mice

Matrix metalloproteinase-8 (MMP-8; neutrophil collagenase) is an important regulator of innate immunity which has onco-suppressive actions in numerous tumor types

Validation the Oral Health Impact Profile Validation the Oral Health Impact Profile (OHIP-14sp) for adults in Spain

Abstract Objectives: The oral health-related quality of life indicators are increasingly used to measure the impact of oral conditions on quality of life to complement clinical data in cross-sectional and longitudinal studies. One of the most internationally spread indicators is the Oral Health Impact Profile (OHIP-14), but it has still never been applied in Spain. The aim of this study was to validate the OHIP-14 for use among adults in Spain. Study design: A cross-sectional study was performed in Granada (Spain). A consecutive sample (n=270) of the Regional Government staff visiting the Employment Risk Prevention Centre for a routine medical check-up participated in this study. All participants self-completed the piloted OHIP-14sp and were examined according to World Health Organization methodology for caries, periodontal disease and prosthesis. Reliability analyses and validity tests were carried out to evaluate the psychometric properties of the OHIP-14sp by using two different methods of total scoring (i.e. the Additive and the Simple Count). Results: The reliability coefficient (Cronbach´s alpha) of the OHIP-14sp was above the recommended 0.7 threshold and considered excellent (alpha: 0.89). Some subjective factors (perceived dental treatment need, complaints about mouth and self-rated oral satisfaction) were strongly associated with both total scoring methods of the OHIP-14sp, supporting the criterion, construct and convergent validity. Moreover the impact levels were mainly influenced by caries data, e.g., number of teeth requiring extraction (r = 0.21; p<0.01) and number of decayed visible teeth (between premolars) (r = 0.17; p<0.01). The prevalence of impacts was 80.7% using the occasional or more frequently threshold. The most prevalently affected OHIP domains were "psychological discomfort" (53.7%), "functional limitation" (51.1%) and "physical pain" (42.2%). Conclusions: The OHIP-14sp is a precise, valid and reliable instrument for assessing oral health-related quality of life among adult population in Spain

A multi-site study on walkability, data sharing and privacy perception using mobile sensing data gathered from the mk-sense platform

Walking is a fundamental part of a physically active lifestyle, it is one of everyday activities that positively impacts health and wellbeing. In this paper we describe the challenges and experiences of conducting a sensing campaign in the wild. We make use of mk-sense; a software platform to facilitate the deployment of collaborative sensing campaigns. We elaborate on two cross-cultural studies conducted in four different countries (Mexico, Turkey, Spain, and Switzerland) with a total of 77 participants. We present a detailed description of the data collected from one of the studies aimed at measuring walkability around three different university campuses. The analysis of the data shows that walkability can be assessed using information from the sensors in the smartphones and results from surveys answered by participants. In addition, we analyze issues about data sharing and privacy awareness