Condicionantes da adoção da tecnologia de despolpamento na cafeicultura.

Os cafeicultores de Venda Nova do Imigrante, ES, que, em sua maioria, são Agricultores familiares, têm adotado novas tecnologias para melhorar a qualidade do café arábica produzido na região. O objetivo deste trabalho é identificar os fatores que determinam a adoção, por parte dos referidos cafeicultores, da tecnologia de despolpamento. O modelo Logit é aqui utilizado como instrumento metodológico. Conforme poderá ser observado nos resultados apresentados pelo estudo, os aspectos relativos a associativismo, a escolaridade, a capital próprio, a produtividade, a rentabilidade e a treinamento determinam a adoção da tecnologia de despolpamento; e as variáveis que mais contribuem para a adoção de tal tecnologia são: rentabilidade, associativismo e treinamento

Análise de componentes principais em séries temporais multivariadas com heteroscedasticidade condicional e outliers: uma aplicação para a poluição do ar, na Região da Grande Vitória, Espírito Santo, Brasil

as questões relativas à qualidade do ar têm se tornado cada vez mais importantes, uma vez que vários problemas de saúde decorrem da poluição atmosférica. Além disso, a poluição do ar contribui para a degradação do meio ambiente e, consequentemente, para o agravamento do efeito estufa. Dessa forma, diversos estudos adotando técnicas estatísticas têm sido realizados, com o intuito de contribuir na tomada de decisões dos agentes públicos e privados no que diz respeito ao combate à poluição, à prevenção de altas concentrações e à formulação de legislações para esse fim. Uma das metodologias estatísticas adotadas é a análise de componentes principais (ACP) clássica, sendo a mesma utilizada para o redimensionamento de rede, em análises de cluster, em análise de regressão, entre outros. No entanto, observa-se que, entre os estudos que têm adotado a ACP clássica, uma característica comum é negligenciar a heteroscedasticidade condicional e/ou a presença de outliers aditivos, que pode levar à resultados espúrios (enganosos), uma vez que a matriz de autocovariância estimada pode ser viesada (estimada incorretamente). Nota-se que as séries temporais relacionadas à poluição atmosférica tendem à apresentar heteroscedasticidade condicional e outliers aditivos. Assim, o primeiro artigo desta tese propôs aplicar um filtro multivariado VARFIMA-GARCH aos dados originais e utilizar a ACP clássica sobre os resíduos do modelo VARFIMA-GARCH. Com esse modelo, buscou-se filtrar, além da volatilidade, a correlação temporal e o comportamento de memória longa. A aplicação da ACP sobre os resíduos do modelo VARFIMA-GARCH mostrou-se mais coerente com as características ambientais da Região da Grande Vitória (RGV), Espírito Santo, Brasil, do que a aplicação usando os dados originais. No segundo artigo, que é a principal contribuição desta tese, a técnica de componentes principais com volatilidade (PVC), proposta por Hu e Tsay (2014), foi estendida para uma abordagem robusta (RPVC), a fim de capturar a volatilidade presente nos processos temporais multivariados, mas, levando-se em consideração os efeitos de outliers aditivos sobre a covariância condicional, uma vez que esses outliers podem mascarar (esconder) a heteroscedasticidade condicional ou, até mesmo, produzir efeitos voláteis espúrios, quando os dados não apresentarem volatilidade. O método RPVC proposto melhorou as predições dos picos de concentração do poluente MP10, na estação de Laranjeiras, RGV

What is the topology of a Schwarzschild black hole?

We investigate the topology of Schwarzschild's black hole through the immersion of this space-time in spaces of higher dimension. Through the immersions of Kasner and Fronsdal we calculate the extension of the Schwarzschild's black hole.Comment: 7 pages. arXiv admin note: substantial text overlap with arXiv:1102.446

Beyond the target area: an integrative view of tDCS-induced motor cortex modulation in patients and athletes

Transcranial Direct Current Stimulation (tDCS) is a non-invasive technique used to modulate neural tissue. Neuromodulation apparently improves cognitive functions in several neurologic diseases treatment and sports performance. In this study, we present a comprehensive, integrative review of tDCS for motor rehabilitation and motor learning in healthy individuals, athletes and multiple neurologic and neuropsychiatric conditions. We also report on neuromodulation mechanisms, main applications, current knowledge including areas such as language, embodied cognition, functional and social aspects, and future directions. We present the use and perspectives of new developments in tDCS technology, namely high-definition tDCS (HD-tDCS) which promises to overcome one of the main tDCS limitation (i.e., low focality) and its application for neurological disease, pain relief, and motor learning/rehabilitation. Finally, we provided information regarding the Transcutaneous Spinal Direct Current Stimulation (tsDCS) in clinical applications, Cerebellar tDCS (ctDCS) and its influence on motor learning, and TMS combined with electroencephalography (EEG) as a tool to evaluate tDCS effects on brain function

Organizational factors associated with readiness to implement and translate a primary care based telemedicine behavioral program to improve blood pressure control: the HTN-IMPROVE study

Abstract Background Hypertension is prevalent and often sub-optimally controlled; however, interventions to improve blood pressure control have had limited success. Objectives Through implementation of an evidence-based nurse-delivered self-management phone intervention to facilitate hypertension management within large complex health systems, we sought to answer the following questions: What is the level of organizational readiness to implement the intervention? What are the specific facilitators, barriers, and contextual factors that may affect organizational readiness to change? Study design Each intervention site from three separate Veterans Integrated Service Networks (VISNs), which represent 21 geographic regions across the US, agreed to enroll 500 participants over a year with at least 0.5 full time equivalent employees of nursing time. Our mixed methods approach used a priori semi-structured interviews conducted with stakeholders (n = 27) including nurses, physicians, administrators, and information technology (IT) professionals between 2010 and 2011. Researchers iteratively identified facilitators and barriers of organizational readiness to change (ORC) and implementation. Additionally, an ORC survey was conducted with the stakeholders who were (n = 102) preparing for program implementation. Results Key ORC facilitators included stakeholder buy-in and improving hypertension. Positive organizational characteristics likely to impact ORC included: other similar programs that support buy-in, adequate staff, and alignment with the existing site environment; improved patient outcomes; is positive for the professional nurse role, and is evidence-based; understanding of the intervention; IT infrastructure and support, and utilization of existing equipment and space. The primary ORC barrier was unclear long-term commitment of nursing. Negative organizational characteristics likely to impact ORC included: added workload, competition with existing programs, implementation length, and limited available nurse staff time; buy-in is temporary until evidence shows improved outcomes; contacting patients and the logistics of integration into existing workflow is a challenge; and inadequate staffing is problematic. Findings were complementary across quantitative and qualitative analyses. Conclusions The model of organizational change identified key facilitators and barriers of organizational readiness to change and successful implementation. This study allows us to understand the needs and challenges of intervention implementation. Furthermore, examination of organizational facilitators and barriers to implementation of evidence-based interventions may inform dissemination in other chronic diseases.http://deepblue.lib.umich.edu/bitstream/2027.42/112820/1/13012_2013_Article_683.pd

Constraints on dark matter models from a Fermi LAT search for high-energy cosmic-ray electrons from the Sun

During its first year of data taking, the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope has collected a large sample of high-energy cosmic-ray electrons and positrons (CREs). We present the results of a directional analysis of the CRE events, in which we searched for a flux excess correlated with the direction of the Sun. Two different and complementary analysis approaches were implemented, and neither yielded evidence of a significant CRE flux excess from the Sun. We derive upper limits on the CRE flux from the Sun's direction, and use these bounds to constrain two classes of dark matter models which predict a solar CRE flux: (1) models in which dark matter annihilates to CREs via a light intermediate state, and (2) inelastic dark matter models in which dark matter annihilates to CREs.Comment: 18 pages, 8 figures, accepted for publication in Physical Review D - contact authors: Francesco Loparco ([email protected]), M. Nicola Mazziotta ([email protected]) and Jennifer Siegal-Gaskins ([email protected]

Fermi-LAT observations of the exceptional gamma-ray outbursts of 3C 273 in September 2009

We present the light curves and spectral data of two exceptionally luminous gamma-ray outburts observed by the Large Area Telescope (LAT) experiment on board Fermi Gamma-ray Space Telescope from 3C 273 in September 2009. During these flares, having a duration of a few days, the source reached its highest gamma-ray flux ever measured. This allowed us to study in some details their spectral and temporal structures. The rise and decay are asymmetric on timescales of 6 hours, and the spectral index was significantly harder during the flares than during the preceding 11 months. We also found that short, very intense flares put out the same time-integrated energy as long, less intense flares like that observed in August 2009.Comment: Corresponding authors: E. Massaro, [email protected]; G. Tosti, [email protected]. 15 pages, 4 figures, published in The Astrophysical Journal Letters, Volume 714, Issue 1, pp. L73-L78 (2010

Fermi Gamma-ray Space Telescope Observations of the Gamma-ray Outburst from 3C 454.3 in November 2010

The flat-spectrum radio quasar 3C 454.3 underwent an extraordinary 5-day gamma-ray outburst in November 2010 where the daily flux measured with the Fermi Large Area Telescope (LAT) at photon energies E>100 MeV reached (66+/-2) x 10^-6 ph cm^-2 s^-1. This is a factor of 3 higher than its previous maximum flux recorded in December 2009 and ~5 times brighter than the Vela pulsar, which is normally the brightest source in the gamma-ray sky. The 3-hr peak flux was (85+/-5) x 10^-6 ph cm^-2 s^-1, corresponding to an apparent isotropic luminosity of 2.1+/-0.2 10^50 erg s^-1, the highest ever recorded for a blazar. In this paper, we investigate the features of this exceptional event in the gamma-ray band of the Fermi-LAT. In contrast to previous flares of the same source observed with the Fermi-LAT, clear spectral changes are observed during the flare.Comment: Contact authors: Lise Escande, Charles Dermer and Benoit Lott. One new figure. Accepted for publication by ApJ

The radio/gamma-ray connection in Active Galactic Nuclei in the era of the Fermi Large Area Telescope

We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the Active Galactic Nuclei (AGN) detected by Fermi during its first year of operation, with the largest datasets ever used for this purpose. We use both archival interferometric 8.4 GHz data (from the VLA and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate-data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the cm radio and the broad band (E>100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability <1e-7 for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6e-6 to 9.0e-8. Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability <1e-7) for both FSRQs and BL Lacs separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.Comment: Accepted for publications by ApJ. Contact authors: M. Giroletti, V. Pavlidou, A. Reime

Periodic Emission from the Gamma-ray Binary 1FGL J1018.6-5856

Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.Comment: Contact authors: R.H.D. Corbet, M. Kerr, C.C. Cheun