1,721,126 research outputs found
Altered brain functional connectivity and impaired short-term memory in Alzheimer's disease
No full textTo examine functional interactions between prefrontal and medial temporal brain areas during face memory, blood flow was measured in patients with Alzheimer's disease and healthy controls using PET. We hypothesized that controls would show correlated activity between frontal and posterior brain areas, including the medial temporal cortex, whereas patients would not, although frontal activity per se might be spared or even increased compared with controls. We used a delayed match to sample paradigm with delays from 1 to 16 s. There was no change in recognition accuracy with increasing delay in controls, whereas patients showed impaired recognition over all delays that worsened as delay increased. Controls showed increased activity in the bilateral prefrontal and parietal cortex with increasing delay, whereas the patients had increased activity in the right prefrontal, anterior cingulate and left amygdala. Increased activity in the right prefrontal cortex was associated with better me..
Cholinergic enhancement improves performance on working memory by modulating the functional activity in distinct brain regions: a positron emission tomography regional cerebral blood flow study in healthy humans
No full textAbstract
Previously, we have shown that physostigmine, an acetylcholinesterase inhibitor, improved performance on a working memory for faces task, as reflected by reduced reaction time (RT), and reduced task-specific regional cerebral blood flow (rCBF) in right prefrontal cortex and, further, that these reductions in RT and right frontal rCBF were significantly correlated. Here we investigated the relation between the effects of physostigmine on task performance and task-specific functional brain response throughout the cortex by examining correlations between physostigmine-related changes in rCBF in all brain areas and changes in RT. In subjects who received an infusion of physostigmine, reduced RT correlated (p<0.001) positively with reduced rCBF in right frontal cortex, left temporal cortex, anterior cingulate, and left hippocampus; and correlated with increased rCBF in medial occipital visual cortex. In subjects who received a placebo infusion of saline, no significant correlations between changes in RT and cortical rCBF were observed. The results show that cholinergically induced improvements in working memory performance are related to alterations in neural activity in multiple cortical regions, including increased neural activity in regions associated with early perceptual processing and decreased neural activity in regions associated with attention, memory encoding, and memory maintenance
Modification of the agar sausage of Ten Cate for bacteriological control
Full text linkCITATION: Horwitz, B. M. 1974. Modification of the agar sausage of Ten Cate for bacteriological control. South African Medical Journal, 48(7):271-273.The original publication is available at http://www.samj.org.zaThe manufacture and use of a disposable plastic syringe as a container for a column of solid culture medium, instead of a plastic sausage casing, is described. The method of sampling and its usefulness in the supervision of the hygiene in hospital kitchens or any food manufacturing establishment, is discussed. Particular reference is made to its use in determining the bacterial load of a surface in contact with food, and its value as a means of educating staff in the necessity for the thorough cleaning of all working surfaces. A standard of evaluation of the bacterial counts obtained by this method of sampling is suggested.Publisher’s versio
Detection of an Alzheimer disease pattern of cerebral metabolism in Down syndrome
No full textCorrelational analysis of cerebral metabolic (rCMRglc) data obtained with positron emission tomography (PET) assesses group differences and has demonstrated reduced frontal-parietal rCMRglc interdependencies in Alzheimer's disease (AD). A multivariate analysis of rCMRglc data assesses individual differences. We recently identified discriminant functions, reflecting frontal-parietal rCMRglc interdependencies, that separated AD from control subjects. To test if the functions would identify an AD rCMRglc pattern in older Down syndrome (DS) adults with (DS DAT+) or without (DS DAT-) dementia, we applied the functions to longitudinal rCMRglc data in: young DS (n = 15), DS DAT- (n = 10), DS DAT+ (n = 4), and young controls (n = 15). All DS DAT+ and some of the later DS DAT- scans were classified as AD. The results provide additional validation of the functions and suggest their utility for the early detection of AD
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Formulación de un plan estratégico para el servicio de urgencia del instituto psiquiátrico “Dr. José Horwitz B.”
No full textUno de los objetivos de este trabajo es señalar la importancia de la Planificación Estratégica como una herramienta en la búsqueda por solucionar la crítica situación en que se encuentra la Atención en Salud del Sector Público en Chile, especialmente la atención de Urgencia en Psiquiatría y Salud Mental. Con esta herramienta desarrollamos, hasta la formulación de Objetivos, un Plan Estratégico para el Servicio de Urgencia del Instituto Psiquiátrico “Dr. José Horwitz B.” y lo presentamos como una alternativa concreta para ser discutido en el establecimiento y lograr despertar la propositividad institucional. En el trabajo presentamos un Marco Teórico de Referencia, que se explica más adelante en forma resumida. Efectuamos un Diagnóstico Situacional en donde hacemos una referencia histórica del Instituto Psiquiátrico “Dr. José Horwitz B.” y de la Salud Pública en Chile. Presentamos la Misión, las Políticas de Salud y de Salud Mental del Ministerio del sector. A partir de la Misión del Servicio de Salud Metropolitano Norte describimos su organización y la del Instituto Psiquiátrico, al cual pertenece el Servicio de Urgencia. Finalmente formulamos un Plan Estratégico para el Servicio de Urgencia del Instituto Psiquiátrico. El horizonte del quehacer organizacional se define en la MISION y los Objetivos, que dan el sentido de existencia y orientan interna y externamente para que sepamos dónde estamos y hacia dónde vamos
A simple method for the primary isolation of Mycobacterium in a carbon dioxide atmosphere
Full text linkCITATION: Horwitz, B. M. & Gultig, R. 1974. A simple method for the primary isolation of Mycobacterium in a carbon dioxide atmosphere. South African Medical Journal, 48(46):1949-1950.The original publication is available at http://www.samj.org.zaA simple, inexpensive method which provides increased CO2 tension for the primary isolation of mycobacteria is described. Using this technique, the primary isolation of mycobacteria from 1114 specimens of sputum, gastric washings, spinal fluids, etc. was increased by 24.2%.Publisher’s versio
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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