1,721,308 research outputs found
Magnetic resonance imaging and positron emission tomography in the diagnosis of neurodegenerative dementias
Full text linkNeuroimaging, both with magnetic resonance imaging (MRI) and positron emission tomography (PET), has gained a pivotal role in the diagnosis of primary neurodegenerative diseases. These two techniques are used as biomarkers of both pathology and progression of Alzheimer’s disease (AD) and to differentiate AD from other neurodegenerative diseases. MRI is able to identify structural changes including patterns of atrophy characterizing neurodegenerative diseases, and to distinguish these from other causes of cognitive impairment, e.g. infarcts, space-occupying lesions and hydrocephalus. PET is widely used to identify regional patterns of glucose utilization, since distinct patterns of distribution of cerebral glucose metabolism are related to different subtypes of neurodegenerative dementia. The use of PET in mild cognitive impairment, though controversial, is deemed helpful for predicting conversion to dementia and the dementia clinical subtype. Recently, new radiopharmaceuticals for the in vivo imaging of amyloid burden have been licensed and more tracers are being developed for the assessment of tauopathies and inflammatory processes, which may underlie the onset of the amyloid cascade. At present, the cerebral amyloid burden, imaged with PET, may help to exclude the presence of AD as well as forecast its possible onset. Finally PET imaging may be particularly useful in ongoing clinical trials for the development of dementia treatments. In the near future, the use of the above methods, in accordance with specific guidelines, along with the use of effective treatments will likely lead to more timely and successful treatment of neurodegenerative dementias
Sonophotocatalytic Degradation of Methyl Orange using TiO2 Photo-catalysts Prepared under Different Experimental Conditions
No full textThe sonochemical oxidation process has been found to be a potentially useful technique for the degradation of organic pollutants in an aqueous environment. In this technique, free radicals are generated during the violent collapse of acoustic cavitation bubbles. These free radicals react with organic pollutant molecules in several reaction pathways and reactive zones. The sonochemical process is often combined with other widely known advanced oxidation processes, such as, ozonation, photocatalysis and Fenton and photoFenton reactions. In this study, sonochemical technique is combined with photocatalysis for the degradation of an organic dye in aqueous environment. A number of photocatalysts were synthesized using conventional technique for use in sonophotocatalysis experiments
MicroRNAs: promising biomarkers and therapeutic targets of acute myocardial ischemia
No full textMicroRNAs (miRNAs), small non-coding RNA molecules that act as negative regulators of gene expression, are involved in a wide range of biological functions and control several cellular processes. This review illustrates miRNA regulation and function in tissue response to acute ischemia, focusing on miRNA role in acute myocardial infarction and describing a subset of miRNAs de-regulated upon cardiac ischemia. These miRNAs may represent "master ischemic" miRNAs, playing a pathogenetic role in one of the different components of tissue response to ischemia. Moreover, circulating miRNAs correlated to myocardial infarction and examples of miRNA involvement in ischemic diseases different from cardiac Ischemia are also discussed. The identification of specific miRNAs as key regulators of cell biology has opened new clinical avenues, and may allow new diagnostic and/or prognostic tools development, as much as innovative therapeutic strategies. Two paradigmatic reports, in which miRNAs have been targeted to improve cardiac function in pre-clinical models of myocardial infarction, are described in detail and confirmed the efficacy of these strategies
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
