793 research outputs found

    Properties of galaxy halos in Clusters and Voids

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    We use the results of a high resolution N-body simulation to investigate the role of the environment on the formation and evolution of galaxy-sized halos. Starting from a set of constrained initial conditions, we have produced a final configuration hosting a double cluster in one octant and a large void extending over two octants of the simulation box. We present results for two statistics: the relationship between 1-D velocity dispersion and mass and the probability distribution of the spin parameter P(λ)P(\lambda). The \svm relationship is well reproduced by the Truncated Isothermal Sphere (TIS) model introduced by Shapiro et al. (1999), although the slope is different from the original prediction. A series of \svm relationships for different values of the anisotropy parameter β\beta, obtained using the theoretical predictions by Lokas and Mamon (2001) for NFW density profiles are found to be only marginally consistent with the data. Using some properties of the equilibrium TIS models, we construct subsamples of {\em fiducial} equilibrium TIS halos from each of the three subregions, and we study their properties. For these halos, we do find an environmental dependence of their properties, in particular of the spin parameter distribution P(λ)P(\lambda). We study in more detail the TIS model, and we find new relationships between the truncation radius and other structural parameters. No gravitationally bound halo is found having a radius larger than the critical value for gravithermal instability for TIS halos (\rt 34.2r0\ge 34.2 r_{0}, where r0r_{0} is the core radius of the TIS solution). We do however find a dependence of this relationship on the environment, like for the P(λ)P(\lambda) statistics. These facts hint at a possible r\^{o}le of tidal fields at determining the statistical properties of halos.Comment: 12 pages, 14 figures. Accepted by MNRAS. Adopted an improved algorithm for halo finding and added a comparison with NFW model

    Land planning through GIS, RS and multicriteria decision analysis. A case study in Sardinia

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    During the last few years researchers and environmental planners have carried on their preliminary studies following an interdisciplinary approach. One of the main issues in this approach is the sustainability of economic development. As a matter of fact, the importance of the studies related to the distribution and the limits of natural resources is widely recognized. This can be accomplished more easily than in present by the use of extremely powerful computer application. The purpose of this contribution is to demonstrate the usefulness of an integrated approach of the GIS and of the RS to planning in complex problems of decision making. Many GIS applications are suited to the input of remote sensing and the integration of these techniques is now accepted in landscape planning. By means of GIS and RS, environmental information can be integrated with administrative, political, social and economic data. GIS, RS and fuzzy logic techniques are used to assist environmental compatibility studies and decision makin

    A contradiction-driven approach to theory formation : conceptual issues, pragmatics in human learning, potentialities

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    In Educational literature, Discovery Learning appears as an approach in which the learner builds up his/her own knowledge by performing experiments within a domain and inferring/increasing rules as a result. Such a constructivist approach has been largely exploited in the design of computational artefacts with learning purposes, the so-called Discovery Learning Environments (DLEs). One known feature of such environments is the autonomy degree required for students to succeed while handling a domain. Additionally, DLEs designers are often challenged to get students actually engaged. Such questions are on the basis of our concerns with the design and usage of particular DLEs, within which learning events occur as a consequence of contradiction detection and overcoming, during human/machine cooperative work. In this paper, we present an artificial agent capable of handling such a contradiction-driven approach of learning, by highlighting the exchanges that the agent should promote with a human learner. The conceptual model supporting the agent’s design relies on the scientific rationale, particularly the empirical approach guided by the theory-experiment confrontation. We shall reinforce the interest of the model for the design of DLEs by presenting its exploitation in a real learning situation in Law. Also, we suggest potential instantiations of the model elsewhere than in Human Learning

    Enhancing livestock productivity through feed and feeding interventions in India and Tanzania

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    Feed interventions often do not work due to the ‘top-down’ approach and blanket promotion irrespective of the context. The MilkIT project’s innovation platforms demonstrated a new way of addressing feed issues. Rapid assessments and the platform discussions ensured producers were strongly engaged in designing and implementing interventions. Participatory action research and training helped to address the problems identified, while the action research centred on introducing improved forages, pasture improvement, reducing feed wastage, feeding adequate rations, and feed conservation. Producers tested different practices, while local researchers monitored the trials. The types of institutions and actors involved in an innovation platform will depend on the particular situation. Innovation platforms may identify issues that a standard research and development approach might not. The entry points will depend on the situation and on the needs of the platform members. It may be important to link interventions to ‘pull factors’ such as markets. As solutions emerge and are tested and accepted, their sustainability must be considered: the trials must be located in the right place, and local communities (and especially women) must have ownership of the process

    Insect repellents: recommendations for use in children

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    OBJETIVO: Apresentar uma revisão bibliográfica sobre o uso de repelentes de insetos em crianças, com ênfase especial na proteção contra mosquitos. FONTES DE DADOS: Realizou-se uma pesquisa bibliográfica nas bases de dados Pubmed e Lilacs, cujos artigos incluíam produtos comercialmente disponíveis no Brasil. Foram selecionados artigos publicados nos últimos dez anos em língua inglesa ou portuguesa, referentes a crianças, obtidos com as seguintes palavras-chave: "insect repellents", "children", "mosquitoes", "N,N-dietil-metatoluamida (DEET)". SÍNTESE DOS DADOS: Entre os repelentes tópicos, DEET, icaridina e óleo natural de eucalipto-limão apresentam, em concentrações adequadas, perfil de segurança favorável e são eficazes na prevenção de picadas de mosquitos em crianças e adultos. Em geral, são indicados para crianças acima de dois anos de idade. Medidas físicas são fundamentais para proteger lactentes jovens, especialmente menores de seis meses, com destaque para o uso de telas com permetrina. CONCLUSÕES: Os mosquitos são vetores de doenças infectoparasitárias que acometem, anualmente, milhões de pessoas no mundo e causam milhares de mortes. O combate aos mosquitos inclui medidas ambientais e de proteção individual. O uso de repelentes tópicos para proteção individual da criança exige cuidados específicos e conhecimento quanto ao produto ideal para cada idade, especialmente quando consideradas sua eficácia e segurança.OBJECTIVE: To present a literature review about the use of insect repellents on children, highlighting the protection against mosquitoes. DATA SOURCES: Pubmed and Lilacs databases were searched for articles in English and Portuguese published in the last ten years with the following key-words: "insect repellents", "children", "mosquitoes", "N,N-dietil-metatoluamida (DEET)". DATA SYNTHESIS: Concerning topical repellents, DEET, icaridine and natural oil of lemon eucalyptus are effective to prevent mosquito bites in children and adults and have favorable safety profile when used in appropriate concentration. They are generally recommended for children older than two years-old. Physical barriers are essential for infant protection, especially if they are six months old or less, with special interest in the permethrin-treated nets. CONCLUSIONS: Mosquitoes are vectors of a variety of infectious and parasitic diseases which annually affect millions of people and cause thousands of deaths worldwide. The combat to mosquitoes includes individual and environmental measures. Topic repellents for children's individual protection demand specific handling attention and knowledge about the ideal product for each age, especially regarding their efficacy and safety

    Fertility Desire and Intention of People Living with HIV/AIDS in Tanzania: A call for Restructuring Care and Treatment Services.

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    Scaling up of antiretroviral therapy (ART) is currently underway in sub-Saharan Africa including, Tanzania, increasing survival of people living with HIV/AIDS (PLWHA). Programmes pay little attention to PLWHA's reproductive health needs. Information on fertility desire and intention would assist in the integration of sexual and reproductive health in routine care and treatment clinics. A cross-sectional study of all PLWHA aged 15--49 residing in Kahe ward in rural Kilimanjaro Tanzania was conducted. Participants were recruited from the community and a local counselling centre located in the ward. Data on socio-demographic, medical and reproductive characteristics were collected through face-to-face interviews. Data were entered and analysed using STATA statistical software. A total of 410 PLWHA with a mean age of 34.2 and constituting 264 (64.4%) females participated. Fifty-one per cent reported to be married/cohabiting, 73.9% lived with their partners and 60.5% were sexually active. The rate of unprotected sex was 69.0% with 12.5% of women reporting to be pregnant at the time of the survey. Further biological children were desired by 37.1% of the participants and lifetime fertility intention was 2.4 children. Increased fertility desire was associated with living and having sex with a partner, HIV disclosure, good perceived health status and CD4 count >=200 cells for both sexes. Reduced desire was associated with havingmore than 2 children among females, divorce or separation, and having a child with the current partner among both males and females. Fertility desire and intention of PLWHA was substantially high though lower than that of the general population in Tanzania. Practice of unprotected sexual intercourse with higher pregnancy rate was observed. Fertility desire was determined by individual perceived health and socio-family related factors. With increasing ART coverage and subsequent improved quality of life of PLWHA, these findings underscore the importance of integrating reproductive health services in the routine care and treatment of HIV/AIDS worldwide. The results also highlight a group of PLWHA with potentially high desire for children who need to be targeted during care

    Campionamento biologico delle catture commerciali Sezione III.C - Variabili biologiche relative al mestiere e dei parametri biologici Sezione III.E - Variabili biologiche relative agli stock del Programma Nazionale Sub-area Geografica (GSA16) – Stretto di Sicilia Anno 2015

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    Il campionamento biologico delle catture/sbarcati commerciali, sezione C – Relative al mestiere ed E – Relative agli stock, nell’ambito del Programma Nazionale per la Raccolta Dati Alieutici (PNRDA) (Reg. Ce. N°199/2008; N°665/2008 e decisione della commissione N°949/2008), ha l’obiettivo di valutare la composizione in taglia e/o età del pescato ed ottenere altre informazioni sulla biologia delle specie bersaglio, quali le chiavi età/lunghezza, la relazione lunghezza/peso, i parametri di crescita, la composizione in sesso e le condizioni di maturità sessuale. Il campionamento delle catture/sbarchi commerciali (campionamento biologico - CAMPBIOL) risulta di grande importanza per conoscere come agisce il prelievo dei diversi ”metiers” sulle diverse specie, in termini di variazioni dell’abbondanza e struttura demografica delle risorse da pesca. Il campionamento biologico risponde, quindi, principalmente alle seguenti esigenze: 1. Ricostruire il pattern di sfruttamento dei diversi ”métiers” per le diverse specie. 2. Ricostruire la struttura demografica delle catture commerciali/sbarchi di ogni specie (in taglia/età), considerando tutti i ”métiers” che incidono significativamente sull’ammontare globale delle catture. 3. Consentire lo studio dei fenomeni biologici rilevanti, quali la crescita ed il ciclo sessuale, che variano nel corso dell’anno. 4. Acquisire informazioni sulla struttura demografica con specifico riferimento allo stadio di maturazione gonadica (maturità/taglia-età) ed alla relazione fra lunghezza e peso corporeo (taglia-peso/età). Il Programma Nazionale prevede il rilievo dei parametri significativi ai fini della caratterizzazione biologica del prodotto della pesca, principalmente nell’ambito di due differenti moduli: Modulo di valutazione del settore della pesca Sezione C – “Variabili biologiche relative al mestiere” Sezione E – “Variabili biologiche relative agli stock
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