1,721,148 research outputs found
Intensive therapy and GFR in type 1 diabetes
No full textThis letter discusses the possibility that the equations used to calculate GFR may have an impact on studies addressed to verify the slope of renal function in diabetic patients
Peripheral Endothelial Function, Shift Work, and Circadian Rhythm Disturbances
No full textSuessenbacher et al reported a reduced peripheral arterial tone in shift workers (SW) compared with nonshift workers (NSW), and this endothelial dysfunction could explain, at least in part, the increased cardiovascular risk in SW. We would like to emphasize the possible pivotal role played by circadian rhythm disturbances. Previous studies reported the existence of a circadian variation in basal vascular tone, due at least in part to increased alpha-sympathetic vasoconstrictor activity, and a morning increase of ischemia-induced coronary vascular resistance, that could contribute to the higher incidence of acute cardiac ischemic events at this time. Morning hours, in fact, represent a highest risk period for the onset of various cardiovascular events, such as myocardial infarction, sudden cardiac death, stroke, aortic aneurysm rupture or dissection. Classically, such pattern has been explained with fluctuations in extracardiac factors, i.e., sympathetic activity, vascular tone, sheer stress, prothrombotic factors, but a recent intriguing line of research is focuse to the possibility that a molecular mechanism intrinsic to the cardiomyocite, such as the circadian clock, may contribute to cardiovascular disease. Circadian clocks can be defined as a transcriptionally based molecular mechanism, composed of both positive and negative feedback loops, with a free-running period of approximately 24 hours. The principal circadian clock or master clock, located in the suprachiasmatic nucleus (SCN), is entrained by light and is supposed to entrain peripheral clocks via neurohumoral modulation. Circadian clocks have been identified within almost all mammalian cell types, including cardiomyocytes, vascular smooth muscle cells, and endothelial cells, and circadian clock genes are essential for cardiovascular health. In fact, bmal1 knockout mice or clock mutant mice exhibited impairment of normal protective endothelial responses to vascular injury with intensified pathological remodelling and predisposition to vascular thrombosis. Anticipation is the principal role of cellular biological clocks, since the capacity to know the time of day represents critical information and selective advantage. In fact, such capacity enables organisms to anticipate daily environmental changes and temporally modify behavioural and physiological functions appropriately, and disruption of such rhythms may lead also to negative consequences. It is possible that a dyssynchronization between different cell types (eg, cardiomyocytes, endothelial cells) could contribute to the pathogenesis of cardiovascular diseases, exacerbating preexisting or underlying cardiovascular conditions. Mice exposed to a disrupting 20-hour instead of 24-hour circadian rhythm showed a complete disruption of their sleep/wake behavior and a marked progression of their cardiovascular disease, eg, myocyte hypertrophy and fibrosis. Since the SNC central clock is entrained by light, it is possible that alterations in light/dark cycle conditions, may have consequences on biological clocks, both central and peripheral. The changes in human daily patterns, secondary to the availability of artificial light, and related possible disruption of circadian rhythms (and sleep/wake patterns), may be responsible of cardiovascular disease onset or progression in SW. The results of this study by Dr Suessenbacher et al deserve high consideration. It is possible that SW/NSW activity should be considered when designing or interpreting studies on cardiovascular risk. At now, we have not conclusive data on whether which amount of circadian rhythm disruption or sleep deprivation may be harmful for cardiovascular system. However, we can agree with the statement that harmony between our biology and our environment is vital to good health
Weekend and higher in-hospital mortality: a relationship between time of occurrence and disease severity may exist?
No full textThe hypothesis that the worst outcome of cardiovascular diseases during weekend may depend on different disease severity is discussed
Reinterpreting Low Resistance in Sb–MoS2 Ohmic Contacts by Means of Ab Initio Transport Simulations
Full text linkBy using an in-house nonequilibrium Green’s function (NEGF)-based ab initio simulator, we investigate the physical mechanisms driving the Sb(0112)–MoS2 system to exhibit the lowest reported contact resistance, RC =42 Ω·μm, to the 2-D semiconductor MoS2. We can find that the transport from the hybridized bands in the Sb–MoS2 heterojunction is quite ineffective and that the back-gateinduced doping of MoS2 in the contact region is crucial to explain the experiments. In fact, by accounting in our ab initio simulations for the presence of a back gate according to the experiments, it is possible to match the band structure of the MoS2 in the Sb–MoS2 heterojunction with that of the external MoS2 layer, which drastically increases the electronic transmission throughout the contact, and ultimately pushes RC close to the quantum limit. Furthermore, we extend the applicability of our previously demonstrated simulation methodology and thus investigate a field-effect transistors (FETs)-like device including an ab initio description of the carrier injection at the Sb–MoS2 contac
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
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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