1,721,244 research outputs found
Complessi solubili di fibrina e livelli di antitrombina II quali indici precoci di ipercoagulabilità nei linfomi maligni
No full textNeuronal responses to optic flow in the monkey parietal area PEc
No full textArea PEc, a high order association area, is located in the dorsocaudal portion of the superior parietal cortex. PEc neurons encode visual motion signals, especially the direction of stimulus motion. The present study tested if PEc neurons also process visual correlates of self-motion. The extracellular activity of single neurons in response to optic flow stimuli was recorded in two monkeys (Macaca fascicularis) trained in a fixation task. The stimuli were produced by random dots simulating planar motion, radial expansion and radial contraction. A substantial number of PEc neurons were specifically activated by radial optic flow and were selective for the position of the focus of expansion with respect to the fovea. Eccentric positions of the focus of expansion were preferred. Almost all neurons showed opponent excitatory-inhibitory activity to expanding-contracting visual fields. Planar motion elicited very weak responses. Optic flow responsiveness is not entirely explained by classical bar sensitivity in PEc neurons, suggesting that optic flow and classical bar responses could serve different mechanisms in the integration of visuo-motor signals to prepare body movements
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
Thyroid Function in Pregnancy
No full textThyroid hormones are crucial for a normal pregnancy and intrauterine fetal development, particularly development of the central nervous system. In the pregnant women there is an increase in thyroxine and triiodothyronine production in response to the estrogen-stimulated rise in the thyroid hormone transport protein, thyroxine-binding globulin. Also, in the first trimester, there is a transient inhibition of thyrotropin, which is mediated, via the negative feedback system, by an increase in thyroid hormones that are stimulated by hCG. Moreover, a large plasma volume, and thus altered distribution of thyroid hormones, increased thyroid hormone metabolism, together with increased renal clearance of iodide are responsible for higher thyroid hormone requirements in pregnancy. The fetus thyroid gland starts functioning after the first trimester. The most important maternal thyroid hormone for the fetus is thyroxine, because it crosses the placental barrier and achieves the fetus. The consequent fetal consumption of maternal thyroid hormone is an additional stimulus to increase maternal thyroid hormone secretion to ensure adequate fetal thyroid hormone availability. Such a new physiological demand requires an adequate iodine intake by pregnant women. The diagnosis of thyroid disease in pregnancy is still based upon serum TSH concentration. Due to the physiological changes occurring during pregnancy, including the increase in hCG and thyroxine-binding globulin levels, TSH normal levels are lower in pregnancy than in nonpregnant women. If internal pregnancy-specific TSH reference ranges are not available, a simple clinical way for TSH reference interval in the first trimester of pregnancy could be calculated as the reference interval for the nonpregnant population decreased by 0.5 mU/L in the upper limit (for most centers ~4 mU/L). In patients with primary hypothyroidism taking levothyroxine, lowering TSH to <2.5 mU/L has been recommended not only to pregnant women but also for women planning to become pregnant
Orchestrating stem cell fate: Novel tools for regenerative medicine
No full textMesenchymal stem cells are undifferentiated cells able to acquire different phenotypes under specific stimuli. In vitro manipulation of these cells is focused on understanding stem cell behavior, proliferation and pluripotency. Latest advances in the field of stem cells concern epigenetics and its role in maintaining self-renewal and differentiation capabilities. Chemical and physical stimuli can modulate cell commitment, acting on gene expression of Oct-4, Sox-2 and Nanog, the main stemness markers, and tissue-lineage specific genes. This activation or repression is related to the activity of chromatin-remodeling factors and epigenetic regulators, new targets of many cell therapies. The aim of this review is to afford a view of the current state of in vitro and in vivo stem cell applications, highlighting the strategies used to influence stem cell commitment for current and future cell therapies. Identifying the molecular mechanisms controlling stem cell fate could open up novel strategies for tissue repairing processes and other clinical applications
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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