Extinction-induced variability in human behavior

Participants earned points by pressing a computer space bar (Experiment 1) or forming rectangles on the screen with the mouse (Experiment 2) under differential-reinforcement-of-low-rate schedules, followed by extinction. Variability in interresponse time (the contingent dimension) increased during extinction, as for Morgan and Lee (1996); variability in diagonal length (the noncontingent dimension, Experiment 2) did not. In Experiment 3, points were contingent on rectangle size. Rectangle size and interresponse-time (the noncontingent dimension) variability increased in extinction. There was greater variability in the contingent dimension during extinction for participants with the more varied history of reinforcement in Experiment 2 but not in Experiment 3. Overall, variability in the contingent dimension increased in extinction, but the degree of increase was affected by reinforcement history

Cryptococcus neoformans Thermotolerance to Avian Body Temperature Is Sufficient For Extracellular Growth But Not Intracellular Survival In Macrophages

Cryptococcus neoformans is a fatal fungal pathogen of humans that efficiently parasitises macrophages. Birds can be colonised by cryptococci and can transmit cryptococcosis to humans via inhalation of inoculated bird excreta. However, colonisation of birds appears to occur in the absence of symptomatic infection. Here, using a pure population of primary bird macrophages, we demonstrate a mechanism for this relationship. We find that bird macrophages are able to suppress the growth of cryptococci seen in mammalian cells despite C. neoformans being able to grow at bird body temperature, and are able to escape from bird macrophages by vomocytosis. A small subset of cryptococci are able to adapt to the inhibitory intracellular environment of bird macrophages, exhibiting a large cell phenotype that rescues growth suppression. Thus, restriction of intracellular growth combined with survival at bird body temperature explains the ability of birds to efficiently spread C. neoformans in the environment whilst avoiding systemic disease

Statistics of extinction and survival in Lotka-Volterra systems

We analyze purely competitive many-species Lotka-Volterra systems with random interaction matrices, focusing the attention on statistical properties of their asymptotic states. Generic features of the evolution are outlined from a semiquantitative analysis of the phase-space structure, and extensive numerical simulations are performed to study the statistics of the extinctions. We find that the number of surviving species depends strongly on the statistical properties of the interaction matrix, and that the probability of survival is weakly correlated to specific initial conditions.Comment: Previous version had error in authors. 11 pages, including 5 figure

Mental health of veterinary nurses and student veterinary nurses: A scoping review

Background: Research has found veterinarians around the world to be at high risk of mental health problems, but far less research has examined veterinary nurses (VNs) and student veterinary nurses (SVNs). This scoping review aimed to map existing evidence on this topic, and identify knowledge gaps. Methods: Literature searches of MEDLINE, PsycINFO, PubMed, Web of Science, and Google Scholar were conducted, and a structured screening and selection procedure applied. To be included, studies had to be peer-reviewed, report relevant results specific to VNs and/or SVNs, and provide descriptive statistics if using quantitative methods. Results: Of 2,118 publications identified, only 13 journal articles met the inclusion criteria. The findings were summarised in five categories: mental health and wellbeing; burnout; stress; compassion fatigue; and moral distress. While the findings of five of the studies suggested that some VNs and SVNs experienced some form of poor mental health, these lacked generalisability or transferability for multiple reasons. There was also inconsistency and ambiguity in the interpretation of findings, and incompatible or oversimplified definitions of mental health problems. Conclusions: More research is needed to address the gaps in existing evidence supporting our understanding of VN and SVN mental health. This should establish baseline measures, and include comparisons with other occupational and national populations

GRUPO DE PERSONAS [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Self-organized criticality in deterministic systems with disorder

Using the Bak-Sneppen model of biological evolution as our paradigm, we investigate in which cases noise can be substituted with a deterministic signal without destroying Self-Organized Criticality (SOC). If the deterministic signal is chaotic the universality class is preserved; some non-universal features, such as the threshold, depend on the time correlation of the signal. We also show that, if the signal introduced is periodic, SOC is preserved but in a different universality class, as long as the spectrum of frequencies is broad enough.Comment: RevTex, 8 pages, 8 figure

Equilibrium and nonequilibrium fluctuations at the interface between two fluid phases

We have performed small-angle light-scattering measurements of the static structure factor of a critical binary mixture undergoing diffusive partial remixing. An uncommon scattering geometry integrates the structure factor over the sample thickness, allowing different regions of the concentration profile to be probed simultaneously. Our experiment shows the existence of interface capillary waves throughout the macroscopic evolution to an equilibrium interface, and allows to derive the time evolution of surface tension. Interfacial properties are shown to attain their equilibrium values quickly compared to the system's macroscopic equilibration time.Comment: 10 pages, 5 figures, submitted to PR

On the algebraic K-theory of the complex K-theory spectrum

Let p>3 be a prime, let ku be the connective complex K-theory spectrum, and let K(ku) be the algebraic K-theory spectrum of ku. We study the p-primary homotopy type of the spectrum K(ku) by computing its mod (p,v_1) homotopy groups. We show that up to a finite summand, these groups form a finitely generated free module over a polynomial algebra F_p[b], where b is a class of degree 2p+2 defined as a higher Bott element.Comment: Revised and expanded version, 42 pages

Preventing and Lessening Exacerbations of Asthma in School-aged children Associated with a New Term (PLEASANT): Recruiting Primary Care Research Sites-the PLEASANT experience

Background: Recruitment of general practices and their patients into research studies is frequently reported as a challenge. The Preventing and Lessening Exacerbations of Asthma in School-aged children Associated with a New Term (PLEASANT) trial recruited 142 general practices, across England and Wales and delivered the study intervention to time and target. Aims: To describe the process of recruitment used within the cluster randomised PLEASANT trial and present results on factors that influenced recruitment. Methods: Data were collected on the number of and types of contact used to gain expression of interest and subsequent randomisation into the PLEASANT trial. Practice size and previous research experience were also collected. Results: The mean number of contacts required to gain expression of interest were m=3.01 (s.d. 1.6) and total number of contacts from initial invitation to randomisation m=6.8 (s.d. 3.5). Previous randomised controlled trial involvement (hazard ratio (HR)=1.81 (confidence interval (CI) 95%, 1.55–2.11) P<0.001) and number of studies a practice had previously engaged in (odds ratio (OR) 1.91 (CI 95%, (1.52–2.42)) P<0.001), significantly influenced whether a practice would participate in PLEASANT. Practice size was not a significant deciding factor (OR=1.04 (95% CI 0.99–1.08) P=0.137). Conclusions: Recruitment to time and target can be achieved in general practice. The amount of resource required for site recruitment should not, however, be underestimated and multiple strategies for contacting practices should be considered. General practitioners with more research experience are more likely to participate in studies

Single-vehicle data of highway traffic - a statistical analysis

In the present paper single-vehicle data of highway traffic are analyzed in great detail. By using the single-vehicle data directly empirical time-headway distributions and speed-distance relations can be established. Both quantities yield relevant information about the microscopic states. Several fundamental diagrams are also presented, which are based on time-averaged quantities and compared with earlier empirical investigations. In the remaining part time-series analyses of the averaged as well as the single-vehicle data are carried out. The results will be used in order to propose objective criteria for an identification of the different traffic states, e.g. synchronized traffic.Comment: 12 pages, 19 figures, RevTe