71 research outputs found

    In general terms, discrete choice models are calibrated using data obtained from Revealed Preference (RP) and Stated Preference (SP) surveys. In transportation planning, one of the main sources of data is the Origin/Destination (O/D) Survey, which is an R

    Get PDF
    Em termos gerais, a calibração do modelo de escolha discreta se dá através de dados obtidos por pesquisas de Preferência Revelada (PR) e Declarada (PD). No planejamento de transportes, uma das principais fontes de dados é a Pesquisa O/D, que é uma pesquisa de PR e descreve as escolhas e comportamentos reais dos indivíduos. Entretanto, não é possível, através desta fonte, caracterizar as alternativas não escolhidas. Este trabalho possui dois objetivos associados: (1) propor um critério para caracterizar, de forma agregada, as alternativas modais, utilizando dados de PR e (2) testar o aprimoramento de estimativas de escolha modal a partir da inclusão das características agregadas das alternativas. Primeiramente, foi utilizado o algoritmo CART (Classification And Regression Tree) para caracterizar os tempos de viagem dos modos de transporte disponíveis na área de estudo (Cidade de São Paulo, Brasil). As viagens foram agrupadas, segundo variáveis independentes selecionadas pelo algoritmo, e foram obtidos valores médios de tempos de viagens para cinco alternativas modais – informação anteriormente não disponível na pesquisa de PR. Finalmente, o aprimoramento da modelagem de escolha discreta, a partir da inclusão dos tempos de viagens médios, é testado através de uma amostra de validação e métricas de desempenho, tais como Percentual de Acertos e Valor do log da Verossimilhança. Observou-se um incremento das estimativas a partir da inclusão das durações de viagens, sendo o método proposto uma contribuição acadêmica para a modelagem a partir de dados de PR.In general terms, discrete choice models are calibrated using data obtained from Revealed Preference (RP) and Stated Preference (SP) surveys. In transportation planning, one of the main sources of data is the Origin/Destination (O/D) Survey, which is an RP survey and describes the actual choices and behaviors of individuals. However, it is not possible, through this source, to characterize the alternatives not chosen. This study has two related aims: (1) to propose a criterion to characterize the travel mode alternatives using RP data, and (2) to test the improvement of travel mode choice estimates based on including characteristics of alternatives. First, the CART (Classification and Regression Tree) algorithm was used to characterize the travel times of the travel modes available in the study area (city of São Paulo, Brazil). The trips were classified according to independent variables selected by the algorithm, and average travel time values were obtained for five travel mode alternatives – information not previously available in the RP survey. Finally, the improvement of discrete choice modeling, based on including average travel times, was tested using a validation sample and performance metrics, such as Hit rates and LogLikelihood values. An increase in estimates was observed from including travel duration, and the proposed method is an academic contribution to the modeling based on RP data

    Qualidade da carne de bovinos superprecoces terminados em confinamento.

    Get PDF
    Avaliou-se a qualidade da carne de 10 bovinos F1 Guzerá-Nelore e 10 F2 Pardo Suíço-Guzerá-Nelore, inteiros, e abatidos precocemente. Na avaliação da carne, foi utilizado o músculo Longissimus dorsi. O delineamento experimental foi o inteiramente ao acaso. Verificaram-se para F1 e F2, respectivamente, médias para umidade de 75,3 e 75,1, extrato etéreo de 1,4 e 1,5, proteína de 23,7 e 23,6 e cinzas de 1,04 e 1,06. Cor em L* de 28,9 e 30,3, médias para cor em a* de 22,6 e 23,4 e cor em b* de 15,3 15,4, força de cisalhamento de 3,4 e 3,5, perda de peso pelo descongelamento de 9,8 e 10,5 e perda pelo cozimento de 15,9 e 15,6. Não houve diferença estatística para nenhuma das variáveis analisadas entre os grupos genéticos

    Articulation and growth of skeletal elements in balanid barnacles (Balanidae, Balanomorpha, Cirripedia)

    Get PDF
    The morphology and ultrastructure of the shells of two balanid species have been examined, paying special attention to the three types of boundaries between plates: (i) radii-parietes, (ii) alae-sheaths, and (iii) parietes-basal plate. At the carinal surfaces of the radii and at the rostral surfaces of the alae, there are series of crenulations with dendritic edges. The crenulations of the radius margins interlock with less prominent features of the opposing paries margins, whereas the surfaces of the longitudinal abutments opposing the ala margins are particularly smooth. The primary septa of the parietes also develop dendritic edges, which abut the internal surfaces of the primary tubes of the base plates. In all cases, there are chitino-proteinaceous organic membranes between the abutting structures. Our observations indicate that the very edges of the crenulations and the primary septa are permanently in contact with the organic membranes. We conclude that, when a new growth increment is going to be produced, the edges of both the crenulations and the primary septa pull the viscoelastic organic membranes locally, with the consequent formation of viscous fingers. For the abutting edges to grow, calcium carbonate must diffuse across the organic membranes, but it is not clear how growth of the organic membranes themselves is accomplished, in the absence of any cellular tissue.This research was funded by projects CGL2017-85118-P (A.G.C., C.S. and C.G.) and CGL2015-64683-P (A.B.R.N.) of the Spanish Ministerio de Economía, Industria y Competitividad, the Unidad Científica de Excelencia UCE-PP2016-05 of the University of Granada (A.G.C. and A.B.R.N.) and the Research Group RNM363 of the Junta de Andalucía (A.G.C.). N.A.L. acknowledges support from CONICYT-Chile through grant nos. FONDECYT 1140938, PCI REDES 170106 and PIA ANILLOS ACT172037, for international collaborative research with A.G.C. and A.B.R.N

    Lutzomyia longipalpis Saliva or Salivary Protein LJM19 Protects against Leishmania braziliensis and the Saliva of Its Vector, Lutzomyia intermedia

    Get PDF
    Leishmaniasis, caused by parasitic protozoa Leishmania, is transmitted by bites of female sand flies that, during blood-feeding, inject humans with parasites and saliva. Sand fly saliva has been investigated as a potential vaccine candidate. It was previously shown that immunization with Lutzomyia longipalpis saliva or salivary proteins protects against cutaneous and visceral leishmaniasis. In the present study, we evaluated if immunization with Lu. longipalpis saliva or DNA plasmid coding for a specific sand fly salivary protein (LJM19) can protect hamsters against L. braziliensis plus another sand fly saliva. Immunization with saliva or LJM19 DNA plasmid induced a mononuclear cell infiltrate which can be a marker of protection. The immune response induced by immunization with these insect molecules was able to protect animals against L. braziliensis infection as shown by the significant reduction in lesion size, parasite load in the ear and draining lymph node. These data show the important role of immune response against sand fly saliva components, suggesting the possibility to develop vaccines using a single component of saliva against Leishmania transmitted by different vectors

    Circulating Levels of Adiponectin, Leptin, Fetuin-A and Retinol-Binding Protein in Patients with Tuberculosis: Markers of Metabolism and Inflammation

    Get PDF
    BACKGROUND: Wasting is known as a prominent feature of tuberculosis (TB). To monitor the disease state, markers of metabolism and inflammation are potentially useful. We thus analyzed two major adipokines, adiponectin and leptin, and two other metabolic markers, fetuin-A and retinol-binding protein 4 (RBP4). METHODS: The plasma levels of these markers were measured using enzyme-linked immunosorbent assays in 84 apparently healthy individuals (=no-symptom group) and 46 patients with active pulmonary TB around the time of treatment, including at the midpoint evaluation (=active-disease group) and compared them with body mass index (BMI), C-reactive protein (CRP), chest radiographs and TB-antigen specific response by interferon-γ release assay (IGRA). RESULTS: In the no-symptom group, adiponectin and leptin showed negative and positive correlation with BMI respectively. In the active-disease group, at the time of diagnosis, leptin, fetuin-A and RBP4 levels were lower than in the no-symptom group [adjusted means 2.01 versus 4.50 ng/ml, P<0.0001; 185.58 versus 252.27 µg/ml, P<0.0001; 23.88 versus 43.79 µg/ml, P<0.0001, respectively]. High adiponectin and low leptin levels were associated with large infiltrates on chest radiographs even after adjustment for BMI and other covariates (P=0.0033 and P=0.0020). During treatment, adiponectin levels increased further and then decreased. Leptin levels remained low. Initial low levels of fetuin-A and RBP4 almost returned to the normal reference range in concert with reduced CRP. CONCLUSIONS: Our data and recent literature suggest that low fat store and underlying inflammation may regulate these metabolic markers in TB in a different way. Decreased leptin, increased adiponectin, or this ratio may be a promising marker for severity of the disease independent of BMI. We should further investigate pathological roles of the balance between these adipokines
    corecore