Probing High-Momentum Protons and Neutrons in Neutron-Rich Nuclei

The atomic nucleus is one of the densest and most complex quantum-mechanical systems in nature. Nuclei account for nearly all the mass of the visible Universe. The properties of individual nucleons (protons and neutrons) in nuclei can be probed by scattering a high-energy particle from the nucleus and detecting this particle after it scatters, often also detecting an additional knocked-out proton. Analysis of electron- and proton-scattering experiments suggests that some nucleons in nuclei form close-proximity neutron–proton pairs with high nucleon momentum, greater than the nuclear Fermi momentum. However, how excess neutrons in neutron-rich nuclei form such close-proximity pairs remains unclear. Here we measure protons and, for the first time, neutrons knocked out of medium-to-heavy nuclei by high-energy electrons and show that the fraction of high-momentum protons increases markedly with the neutron excess in the nucleus, whereas the fraction of high-momentum neutrons decreases slightly. This effect is surprising because in the classical nuclear shell model, protons and neutrons obey Fermi statistics, have little correlation and mostly fill independent energy shells. These high-momentum nucleons in neutron-rich nuclei are important for understanding nuclear parton distribution functions (the partial momentum distribution of the constituents of the nucleon) and changes in the quark distributions of nucleons bound in nuclei (the EMC effect). They are also relevant for the interpretation of neutrino-oscillation measurements and understanding of neutron-rich systems such as neutron stars

Detection of psychiatric morbidity in the primary medical care setting in Brazil Distúrbios psiquiátricos e assistência primária à saúde no Brasil

The aims of this study were a) to assess the ability of primary care doctors to make accurate ratings of psychiatric disturbance and b) to evaluate the use of a case-finding questionnaire in the detection of psychiatric morbidity. The estudy took place in three primary care clinics in the city of São Paulo, Brazil, during a six-month survey. A time sample of consecutive adult attenders were asked to complete a case-finding questionnaire for psychiatric disorders (the Self Report Questionnaire - SRQ) and a subsample were selected for a semi-structured psychiatric interview (the Clinical Interview Schedule - CIS). At the end of the consultation the primary care doctors were asked to assess, in a standardized way, the presence or absence of psychiatric disorder; these assessments were then compared with that ratings obtained in the psychiatric interview. A considerable proportion of minor psychiatric morbidity remained undetected by the three primary care doctors: the hidden morbidity ranged from 22% to 79%. When these were compared to those of the case-finding questionnaire, they were consistently lower, indicating that the use of these instruments can enhance the recognition of psychiatric disorders in primary care settings. Four strategies for adopting the questionnaire are described, and some of the clinical consequences of its use are discussed.<br>Objetivou-se avaliar a habilidade de clínicos gerais em diagnosticar distúrbios emocionais na assistência primária, e investigar a possibilidade de se introduzir um questionário de "screening" para auxiliar o diagnóstico de doenças psiquiátricas. O estudo foi realizado em dois centros de saúde e um ambulatório de clínica geral na cidade de São Paulo (Brasil), por um período de 6 meses. Uma amostra representativa de pacientes adultos (16 anos) atendidos por clínico geral preencheu um questionário de "screening" para distúrbios psiquiátricos menores. Uma sub-amostra foi selecionada para entrevista psiquiátrica semi-estruturada, segundo a versão brasileira da "Clinical Interview Schedule" (CIS). No final da consulta os clínicos gerais avaliaram, através de uma escala padronizada, se o paciente apresentava ou não um distúrbio psiquiátrico e a severidade do mesmo. Considerável número de pacientes que apresentavam distúrbios psiquiátricos menores não foram identificados pelos clínicos gerais (de 22% a 79%), sendo que o questionário de "screening" contribuiria sobremaneira na identificação desses distúrbios. São apresentadas quatro estratégias que podem ser consideradas na adoção do "screening", e discutidas as conseqüências clínicas que circunscrevem a aplicação desse instrumental