1,060 research outputs found

    Autonomous three-dimensional formation flight for a swarm of unmanned aerial vehicles

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    This paper investigates the development of a new guidance algorithm for a formation of unmanned aerial vehicles. Using the new approach of bifurcating potential fields, it is shown that a formation of unmanned aerial vehicles can be successfully controlled such that verifiable autonomous patterns are achieved, with a simple parameter switch allowing for transitions between patterns. The key contribution that this paper presents is in the development of a new bounded bifurcating potential field that avoids saturating the vehicle actuators, which is essential for real or safety-critical applications. To demonstrate this, a guidance and control method is developed, based on a six-degreeof-freedom linearized aircraft model, showing that, in simulation, three-dimensional formation flight for a swarm of unmanned aerial vehicles can be achieved

    Determinants of antibody persistence across doses and continents after single-dose rVSV-ZEBOV vaccination for Ebola virus disease: an observational cohort study.

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    BACKGROUND: The recombinant vesicular stomatitis virus (rVSV) vaccine expressing the Zaire Ebola virus (ZEBOV) glycoprotein is efficacious in the weeks following single-dose injection, but duration of immunity is unknown. We aimed to assess antibody persistence at 1 and 2 years in volunteers who received single-dose rVSV-ZEBOV in three previous trials. METHODS: In this observational cohort study, we prospectively followed-up participants from the African and European phase 1 rVSV-ZEBOV trials, who were vaccinated once in 2014-15 with 300 000 (low dose) or 10-50 million (high dose) plaque-forming units (pfu) of rVSV-ZEBOV vaccine to assess ZEBOV glycoprotein (IgG) antibody persistence. The primary outcome was ZEBOV glycoprotein-specific IgG geometric mean concentrations (GMCs) measured yearly by ELISA compared with 1 month (ie, 28 days) after immunisation. We report GMCs up to 2 years (Geneva, Switzerland, including neutralising antibodies up to 6 months) and 1 year (Lambaréné, Gabon; Kilifi, Kenya) after vaccination and factors associated with higher antibody persistence beyond 6 months, according to multivariable analyses. Trials and the observational study were registered at ClinicalTrials.gov (Geneva: NCT02287480 and NCT02933931; Kilifi: NCT02296983) and the Pan-African Clinical Trials Registry (Lambaréné PACTR201411000919191). FINDINGS: Of 217 vaccinees from the original studies (102 from the Geneva study, 75 from the Lambaréné study, and 40 from the Kilifi study), 197 returned and provided samples at 1 year (95 from the Geneva study, 63 from the Lambaréné, and 39 from the Kilifi study) and 90 at 2 years (all from the Geneva study). In the Geneva group, 44 (100%) of 44 participants who had been given a high dose (ie, 10-50 million pfu) of vaccine and who were seropositive at day 28 remained seropositive at 2 years, whereas 33 (89%) of 37 who had been given the low dose (ie, 300 000 pfu) remained seropositive for 2 years (p=0·042). In participants who had received a high dose, ZEBOV glycoprotein IgG GMCs decreased significantly between their peak (at 1-3 months) and month 6 after vaccination in Geneva (p0·05). Neutralising antibodies seem to be less durable, with seropositivity dropping from 64-71% at 28 days to 27-31% at 6 months in participants from the Geneva study. INTERPRETATION: Antibody responses to single-dose rVSV-ZEBOV vaccination are sustained across dose ranges and settings, a key criterion in countries where booster vaccinations would be impractical. FUNDING: The Wellcome Trust and Innovative Medicines Initiative 2 Joint Undertaking

    Effects of anisotropic interactions on the structure of animal groups

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    This paper proposes an agent-based model which reproduces different structures of animal groups. The shape and structure of the group is the effect of simple interaction rules among individuals: each animal deploys itself depending on the position of a limited number of close group mates. The proposed model is shown to produce clustered formations, as well as lines and V-like formations. The key factors which trigger the onset of different patterns are argued to be the relative strength of attraction and repulsion forces and, most important, the anisotropy in their application.Comment: 22 pages, 9 figures. Submitted. v1-v4: revised presentation; extended simulations; included technical results. v5: added a few clarification

    From normal cell types to malignant phenotypes

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    The phenotypic diversity of breast cancer has been proposed to result from different target cell types undergoing oncogenic transformation and giving rise to cancer stem cells. Global gene expression profiling revealed distinct molecular phenotypes and some of these signatures were held to reflect the cell of origin, with the basal carcinomas arising from basal/progenitor cells. Recent work challenges this view by providing evidence that luminal precursor cells are involved in the pathogenesis of basal breast cancers and has made new links between normal cell populations and molecular tumor phenotypes

    Psychologists’ Authenticity: Implications for Work in Professional and Therapeutic Settings

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    Derek J. Burks, PhD, is a licensed psychologist and postdoctoral psychology fellow at the Pacific Northwest Mental Illness Research, Education, and Clinical Center (MIRECC), located within the Veterans Affairs Medical Center in Portland, Oregon. He obtained his PhD in counseling psychology from the University of Oklahoma. His current research focuses on health disparities, posttraumatic stress disorder among sexual-minority U.S. military veterans, and culturally appropriate mental health treatment for American Indians.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Exploración vocacional en adolescentes: evaluación de una intervención en clase

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    Analisa-se o impacto de uma intervenção psicológica na exploração e tomada de decisão vocacional em adolescentes portugueses. Em contexto curricular e de classe, desenvolveram-se actividades de exploração do meio e do Eu com 39 alunos e 43 alunas do 9o ano, entre 13 e 17 anos (M=14,4, DP=0,95). Em um design pré/pós-teste, aplicaram-se o Career Exploration Survey (CES) e o Career Decision Difficulties Questionnaire (CDDQ). Os resultados do teste do sinal evidenciaram ganhos significativos (p<0,01) nas dimensões de exploração e diminuição significativa da falta de informação profissional (p<0,01) e do total das dificuldades de decisão (p<0,05). Observou-se um padrão de correlações negativas (ró de Spearman) entre as duas medidas vocacionais, evidenciando uma relação entre a informação explorada na intervenção e a diminuição das dificuldades de decisão por falta de motivação. Em geral, os resultados suportam a importância do papel da exploração da carreira na diminuição das dificuldades de tomada de decisão.This study analyses the impact of a psychological intervention to promote vocational exploration and decisionmaking in Portuguese adolescents. Activities to foster exploration of self and environment were developed in a classroom program with 39 boys and 43 girls, all 9th grade students, between 13 and 17 years of age (M=14,4, SD=0.95). Following a pre/post-test design, the Career Exploration Survey (CES), and the Career Decision Difficulties Questionnaire (CDDQ) were administered. Results of sign-test showed significant increments (p<0.01) in all of the exploration dimensions, significant reduction of lack of occupational information (p<0.01) and of the total of career decision-making difficulties (p<0.05). Negative correlations (Spearman’s rho) between the two career measures was observed, evidencing a relationship between information explored during intervention and decreased difficulty with decision-making due to lack of motivation. In general, results support the importance of career exploration on diminishing decision-making difficulties.Evalúa-se el impacto de una intervención psicológica que fomenta la exploración y la decisión vocacional en adolescentes portugueses. Fueran efectuadas actividades de exploración del medio ambiente y del yo en contexto curricular de clase con 39 alumnos y 43 alumnas del curso 3º ESO, 13 hasta 17 años (M=14,4, DP=0,95). Utilizó-se un diseño pre/posteste, con aplicación del Career Exploration Survey (CES) y Career Decision Difficulties Questionnaire (CDDQ). Resultados del test del señal evidencian beneficios significativos (p<0,01) en las dimensiones de la exploración, reducción significativa de ausencia de información ocupacional (p<0,01) y total de dificultades de decisión (p<0,05). Ha sido observado un patrón de correlaciones negativas (ró de Spearman) entre las dos medidas vocacionales, mostrando relación entre la información explorada e la disminución de las dificultades de decisión por falta de motivación. En general, resultados sostienen la importancia de la exploración de carrera en la disminución de las dificultades de decisió
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