671 research outputs found
Classical dynamics of the optomechanical modes of a Bose-Einstein condensate in a ring cavity
We consider a cavity optomechanical system consisting of a Bose-Einstein
condensate (BEC) interacting with two counterpropagating traveling-wave modes
in an optical ring cavity. In contrast to the more familiar case where the
condensate is driven by the standing-wave field of a high- Fabry-P{\'e}rot
cavity we find that both symmetric and antisymmetric collective density side
modes of the BEC are mechanically excited by the light field. In the
semiclassical, mean-field limit where the light field and the zero-momentum
mode of the condensate are treated classically the system is found to exhibit a
rich multistable behavior, including the appearance of isolated branches of
solutions (isolas). We also present examples of the dynamics of the system as
input parameters such as the frequency of the driving lasers are varied
The Intensity Profile of the Solar Supergranulation
We have measured the average radial (cell center to network boundary) profile
of the continuum intensity contrast associated with supergranular flows using
data from the Precision Solar Photometric Telescope (PSPT) at the Mauna Loa
Solar Observatory (MLSO). After removing the contribution of the network flux
elements by the application of masks based on Ca II K intensity and averaging
over more than 10^5 supergranular cells, we find a ~ 0.1% decrease in red and
blue continuum intensity from the supergranular cell centers outward,
corresponding to a ~ 1.0 K decrease in brightness temperature across the cells.
The radial intensity profile may be caused either by the thermal signal
associated with the supergranular flows or a variation in the packing density
of unresolved magnetic flux elements. These are not unambiguously distinguished
by the observations, and we raise the possibility that the network magnetic
fields play an active role in supergranular scale selection by enhancing the
radiative cooling of the deep photosphere at the cell boundaries.Comment: Accepted to Ap
Impacts of the Proposals For Tariff Reductions in Non-Agricultural Market Access (Nama)
O Estudo Visa Avaliar os Impactos de Propostas Alternativas de Redução da Proteção Tarifária de Bens NĂŁo-AgrĂcolas Sobre a Economia Brasileira Usando um Modelo de EquilĂbrio Geral Computável. Foram Simulados os Impactos da Implementação de Cortes Tarifários de Acordo com Diferentes Coeficientes para a FĂłrmula SuĂça. as Simulações Foram Realizadas com o Modelo Gtap e Todos os Choques Tarifários Foram Calculados a Partir de Informações da Base de Dados Macmap. AlĂ©m de Analisar Resultados MacroeconĂ´micos e Setoriais, TambĂ©m foi Testada a Sensibilidade dos Resultados em Relação ao Aumento das Elasticidades de Armington e Ă€ OcorrĂŞncia de uma Simultânea Liberalização de Tarifas Sobre Bens AgrĂcolas.
Lower bound for the segregation energy in the Falicov-Kimball model
In this work, a lower bound for the ground state energy of the
Falicov-Kimball model for intermediate densities is derived. The explicit
derivation is important in the proof of the conjecture of segregation of the
two kinds of fermions in the Falicov-Kimball model, for sufficiently large
interactions. This bound is given by a bulk term, plus a term proportional to
the boundary of the region devoid of classical particles. A detailed proof is
presented for density n=1/2, where the coefficient 10^(-13) is obtained for the
boundary term, in two dimensions. With suitable modifications the method can
also be used to obtain a coefficient for all densities.Comment: 8 pages, 2 figure
Llama single domain antibodies as a tool for molecular mimicry
In camelids, a subset of the immunoglobulins consists of heavy-chain homodimers devoid of light chains, and are thus called heavy-chain IgGs (hcIgGs). Their variable region (VHH) is the smallest antigen-binding fragment possible, and being just one polypeptide chain it is especially suitable for engineering. In particular, camelid single domain antibodies might be very useful for molecular mimicry and anti-idiotypic vaccination. In the present work, we show that llamas immunized with an anti-DNA mouse mAb develop an important anti-Id response. Selection of VHHs by phage display, with specific elution of bound phages with the external antigenic DNA, shows that selected private anti-Id VHHs compete for binding to the external antigen and bear a functional mimicry of the DNA. These results indicate that llama anti-Id single domain antibodies would be an excellent tool for molecular mimicry studies.Fil: Zarebski, Laura M.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. Instituto de Investigaciones BioquĂmicas de Buenos Aires. FundaciĂłn Instituto Leloir. Instituto de Investigaciones BioquĂmicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Urrutia, Mariela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. Instituto de Investigaciones BioquĂmicas de Buenos Aires. FundaciĂłn Instituto Leloir. Instituto de Investigaciones BioquĂmicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Goldbaum, Fernando Alberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. Instituto de Investigaciones BioquĂmicas de Buenos Aires. FundaciĂłn Instituto Leloir. Instituto de Investigaciones BioquĂmicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de QuĂmica BiolĂłgica de la Facultad de Ciencias Exactas y Naturales; Argentin
Retinal Nerve Fiber Layer Features Identified by Unsupervised Machine Learning on Optical Coherence Tomography Scans Predict Glaucoma Progression.
Purpose:To apply computational techniques to wide-angle swept-source optical coherence tomography (SS-OCT) images to identify novel, glaucoma-related structural features and improve detection of glaucoma and prediction of future glaucomatous progression. Methods:Wide-angle SS-OCT, OCT circumpapillary retinal nerve fiber layer (cpRNFL) circle scans spectral-domain (SD)-OCT, standard automated perimetry (SAP), and frequency doubling technology (FDT) visual field tests were completed every 3 months for 2 years from a cohort of 28 healthy participants (56 eyes) and 93 glaucoma participants (179 eyes). RNFL thickness maps were extracted from segmented SS-OCT images and an unsupervised machine learning approach based on principal component analysis (PCA) was used to identify novel structural features. Area under the receiver operating characteristic curve (AUC) was used to assess diagnostic accuracy of RNFL PCA for detecting glaucoma and progression compared to SAP, FDT, and cpRNFL measures. Results:The RNFL PCA features were significantly associated with mean deviation (MD) in both SAP (R2 = 0.49, P < 0.0001) and FDT visual field testing (R2 = 0.48, P < 0.0001), and with mean circumpapillary RNFL thickness (cpRNFLt) from SD-OCT (R2 = 0.58, P < 0.0001). The identified features outperformed each of these measures in detecting glaucoma with an AUC of 0.95 for RNFL PCA compared to an 0.90 for mean cpRNFLt (P = 0.09), 0.86 for SAP MD (P = 0.034), and 0.83 for FDT MD (P = 0.021). Accuracy in predicting progression was also significantly higher for RNFL PCA compared to SAP MD, FDT MD, and mean cpRNFLt (P = 0.046, P = 0.007, and P = 0.044, respectively). Conclusions:A computational approach can identify structural features that improve glaucoma detection and progression prediction
Impacto de Entrada da Venezuela no Mercosul: Uma Simulação com Modelo de EquilĂbrio Geral Computável
O Objetivo deste Estudo Ă© Avaliar os Impactos da Entrada da Venezuela no Mercosul Utilizando para Tanto o Modelo de EquilĂbrio Geral Computável Multi-Setorial e Multi-Regional Denominado Global Trade Analysis Project (Gtap). AlĂ©m da Introdução, o Estudo Está Dividido em Outras 5 Seções. na Seção 2, sĂŁo Analisados os Documentos Mais Relevantes Assinados Pelos Estados-Parte, Ressaltando a Relativa Rapidez da Assinatura do Acordo de AdesĂŁo da Venezuela ao Bloco; na Seção 3, Descreve-Se o Estado Atual do Fluxo de ComĂ©rcio entre Venezuela e Mercosul, Assim como as Condições de Acesso a Mercados, Ressaltando a Importância da Venezuela para o Mercosul e a Proteção Ligeiramente Maior Aplicada Pela Economia Venezuelana Quando Comparada com a do Mercosul. na Seção Seguinte, Descrevem-Se os Choques Tarifários Implementados em TrĂŞs Simulações, Representativas da AdesĂŁo da Venezuela ao Mercosul, AlĂ©m de HipĂłteses de Fechamento do Modelo. na Seção 5, os Resultados da Simulação sĂŁo Apresentados e Discutidos. Sinteticamente, Chama-Se Ă€ Atenção para o Aumento de Bem Estar nos PaĂses Envolvidos e o Significativo Impacto Setorial, Especialmente nos Setores de AutomĂłveis, Máquinas e Equipamentos e TĂŞxteis e Vestuário. uma Ăšltima Seção Sumaria as Principais Conclusões do Trabalho.
Common Mental Disorders And The Use Of Psychoactive Drugs: The Impact Of Socioeconomic Conditions
Objective: To evaluate the infl uence of socioeconomic conditions on the association between common mental disorders and the use of health services and psychoactive drugs. Methods: This was a population-based cross-sectional study conducted in the city of Botucatu, Southeastern Brazil. The sample was probabilistic, stratifi ed and cluster-based. Interviews with 1,023 subjects aged 15 years or over were held in their homes between 2001 and 2002. Common mental disorders were evaluated using the Self-Reporting Questionnaire (SRQ-20). The use of services was investigated in relation to the fortnight preceding the interview and the use of psychotropic drugs, over the preceding three days. Logistic regression was used for multivariable analysis, and the design effect was taken into consideration. Results: Out of the whole sample, 13.4% (95% CI: 10.7;16.0) had sought health services over the fortnight preceding the interview. Seeking health services was associated with female gender (OR=2.0) and the presence of common mental disorders (OR=2.2). 13.3% of the sample (95% CI: 9.2;17.5) said they had used at least one psychotropic drug, especially antidepressives (5.0%) and benzodiazepines (3.1%). In the multivariable analysis, female gender and the presence of common mental disorders remained associated with the use of benzodiazepines. Per capita income presented a direct and independent association with the use of psychoactive drugs: the greater the income, the greater the use of these drugs was. Conclusions: Lower income was associated with the presence of common mental disorders, but not with the use of psychotropic drugs. 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