Distribution and Kinematics of O VI in the Galactic Halo

FUSE spectra of 100 extragalactic objects are analyzed to obtain measures of O VI absorption along paths through the Milky Way thick disk/halo. Strong O VI absorption over the approximate velocity range from -100 to 100 km/s reveals a widespread but highly irregular distribution of thick disk O VI, implying the existence of substantial amounts of hot gas with T ~ 3x10^5 K in the Milky Way halo. Large irregularities in the distribution of the absorbing gas are found to be similar over angular scales extending from less than one to 180 degrees, indicating a considerable amount of small and large scale structure in the gas. The overall distribution of Galactic O VI is not well described by a symmetrical plane-parallel layer of patchy O VI absorption. The simplest departure from such a model that provides a reasonable fit to the observations is a plane-parallel patchy absorbing layer with a scale height of 2.3 kpc, and a 0.25 dex excess of O VI in the northern Galactic polar region. The O VI absorption has a Doppler parameter b = 30 to 99 km/s, with an average value of 60 km/s . Thermal broadening alone cannot explain the large observed profile widths. The average O VI absorption velocities toward high latitude objects range from -46 to 82 km/s, with a sample average of 0 km/s and a standard deviation of 21 km/s. O VI associated with the thick disk moves both toward and away from the plane with roughly equal frequency. A combination of models involving the radiative cooling of hot fountain gas, the cooling of supernova bubbles in the halo, and the turbulent mixing of warm and hot halo gases is required to explain the presence of O VI and other highly ionized atoms found in the halo. (abbreviated)Comment: 70 pages, single-spaced, PDF format. Bound copies of this manuscript and two accompanying articles are available upon request. Submitted to ApJ

Self-regulation: differences by year and area in college students

Neste estudo procura-se analisar a existência de diferenças nas estratégias auto-regulatórias de alunos universitários em áreas de formação distintas. Participaram 518 alunos de três níveis (inicial, intermédio e final) das áreas de ciências e humanidades. Aplicou-se a escala “CHE – Comportamentos e hábitos de estudo e aprendizagem”, que avalia cinco dimensões: estratégias cognitivas de transformação e manipulação da informação, organização e planeamento de rotinas, gestão e monitorização, aquisição e selecção da informação, e reforço motivacional. Verificou-se uma maior utilização das estratégias cognitivas e metacognitivas de gestão e monitorização apesar dos resultados não indicarem diferenças substantivas entre os alunos diferenciados por nível e área. Os resultados podem indicar estabilidade nos comportamentos ou limitações no tipo de instrumento e amostra utilizada. O estudo de mudanças nestas estratégias deverá ser conduzido com recurso a delineamentos longitudinais. O impacto da estabilidade deverá ser ponderado na elaboração de projectos de intervenção.In this study we seek to analyze the existence of differences in self-regulating strategies of university students in distinct graduation areas. 518 students of three levels (initial, intermediate and final) of science and humanities fields participated. We used the scale “Behavior and study skill”, which evaluates five dimensions: cognitive strategies of transformation and manipulation of information, organization and planning of routines, management and monitoring, information acquisition and selection, and motivational reinforcement. A higher use of cognitive and metacognitive strategies of management and monitoring was noted although the results do not indicate major differences between students in different levels and graduation areas. The results can indicate stability in the behaviors or limitations in the type of instrument and in the sample used. The study of changes in these strategies must be carried out having in mind longitudinal outlines. The impact of the stability should be taken into account while elaborating intervention projects.(undefined

Development of a psychiatric disorder linked to cerebellar lesions

Cerebellar dysfunction plays a critical role in neurodevelopmental disorders with long-term behavioral and neuropsychiatric symptoms. A 43-year-old woman with a cerebellum arteriovenous malformation and history of behavioral dysregulation since childhood is described. After the rupture of the cerebellar malformation in adulthood, her behavior morphed into specific psychiatric symptoms and cognitive deficits occurred. The neuropsychological assessment evidenced impaired performance in attention, visuospatial, memory, and language domains. Moreover, psychiatric assessment indicated a borderline personality disorder. Brain MRI examination detected macroscopic abnormalities in the cerebellar posterior lobules VI, VIIa (Crus I), and IX, and in the posterior area of the vermis, regions usually involved in cognitive and emotional processing. The described patient suffered from cognitive and behavioral symptoms that are part of the cerebellar cognitive affective syndrome. This case supports the hypothesis of a cerebellar role in personality disorders emphasizing the importance of also examining the cerebellum in the presence of behavioral disturbances in children and adults

Structural cerebellar correlates of cognitive functions in spinocerebellar ataxia type 2

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease involving the cerebellum and characterized by a typical motor syndrome. In addition, the presence of cognitive impairment is now widely acknowledged as a feature of SCA2. Given the extensive connections between the cerebellum and associative cerebral areas, it is reasonable to hypothesize that cerebellar neurodegeneration associated with SCA2 may impact on the cerebellar modulation of the cerebral cortex, thus resulting in functional impairment. The aim of the present study was to investigate and quantitatively map the pattern of cerebellar gray matter (GM) atrophy due to SCA2 neurodegeneration and to correlate that with patients' cognitive performances. Cerebellar GM maps were extracted and compared between SCA2 patients (n = 9) and controls (n = 33) by using voxel-based morphometry. Furthermore, the relationship between cerebellar GM atrophy and neuropsychological scores of the patients was assessed. Specific cerebellar GM regions were found to be affected in patients. Additionally, GM loss in cognitive posterior lobules (VI, Crus I, Crus II, VIIB, IX) correlated with visuospatial, verbal memory and executive tasks, while additional correlations with motor anterior (V) and posterior (VIIIA, VIIIB) lobules were found for the tasks engaging motor and planning components. Our results provide evidence that the SCA2 neurodegenerative process affects the cerebellar cortex and that MRI indices of atrophy in different cerebellar subregions may account for the specificity of cognitive symptomatology observed in patients, as result of a cerebello-cerebral dysregulation

Report of a consensus workshop, Siena, Italy, January 17-18, 1992. Early diagnosis of HIV infection in infants

To promote progress in the research and development of early diagnostic tests for HIV in young children an international workshop was held on January 17-18, 1992, in Siena, Italy. Experts on pediatric AIDS, diagnostic retrovirology, and immunodiagnosis discussed and summarized the state-of-the-art and made recommendations for general application of several tests and further evaluation and continued research for other candidate tests. From the discussions it was clear that the field has advanced beyond the time when it was necessary to wait until the infant reached 18 months of age before attempting the diagnosis with conventional serologic tests for HIV. About half of infected infants can now be identified at birth, approximately 90% by 3 months of age, and almost all by 6 months of age using HIV culture and polymerase chain reaction assays. IgA antibody tests and p24 antigen tests have also proved useful, although they are not as sensitive in newborn infants. The fact that HIV can be detected in only one-half of infected infants at the time of birth points to the need for further research on the timing of transmission and the natural history of perinatally acquired HIV infection to understand the limitations of current early diagnostic tests and to develop new approaches to overcome these problems