1,721,000 research outputs found
Scanning electron microscopy and human sperm pathology
No full textThis paper has been carried out in order to inquire whether some of the best known human malformations can be recongnized by scanning electron microscopy. The SEM appearance of 'straight tailed', 'empty tailed', 'short tailed', 'round headed', and related to the inner structure. Straight tails and empty tails are quite evident at SEM. These defects are due to severe axonemal defects, related to dynein and tubulin deficiencies: '9+0', 'arm less' and 'axoneme less' spermatozoa are included in this category. Short tails and round heads are still more evident defects, and round heads are still more evident defects, due to complete absence of tail structures or acrosome and easily recognizable at SEM. Double spermatozoa are consistently in patients having abnormally high prolactin level and SEM is obviously sufficient for the diagnosis. Finally, spermatozoa in aged individuals show in SEM a peculiar shapse due to absence of immature stages, reduced cytoplasm, disordered axoneme. It is concluded that SEM examination is a good tool for the identification of most of the best known human sperm abnormalities
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
NOVEL INSIGHT ON THE FINE MECHANISMS OF THE ACTION OF METHAMPHETAMINE WITHIN CATECHOLAMINERGIC NEURONS
Full text linkMethamphetamine (METH) is abused worldwide and it represents a threaten for public health. METH exposure induces a variety of detrimental effects. In fact, METH produces a number of oxidative species, which lead to lipid peroxidation, protein misfolding and nuclear damage. Cell clearing pathways such as proteasome (UP) and autophagy (ATG) are involved in METH-induced oxidative damage. Although these pathways were traditionally considered to operate as separate metabolic systems, recent studies demonstrate their interconnection at functional and biochemical level. Very recently, the convergence between UP and ATG was evidenced within a single organelle named autophagoproteasome (APP), which is suppressed by mTOR activation. In the present research study, the occurrence of APP during METH toxicity was analyzed. In fact, co-immune-precipitation indicates a binding between LC3 and P20S particles, which also recruit p62 and alpha-synuclein. The amount of METH-induced toxicity correlates with APPs levels. Specific markers for ATG and UP, such as LC3 and P20S in the cytosol, and within METH-induced vacuoles, were measured at different doses and time intervals following METH administered either alone, or combined with mTOR modulators. Different approaches were used to document the effects of mTOR modulation on METH toxicity and the merging of UP with ATG markers within APPs. METH-induced cell death is prevented by mTOR inhibition while it is worsened by mTOR activation, which correlates with the amount of autophagoproteasomes. The present data, which apply to METH toxicity, are also relevant to provide a novel insight into cell clearing pathways to counteract several kind of oxidative damage
“Sport and Anatomy”: Teaching, Research, and Assistance at the University of Pisa
Full text linkIntroduction: Over the last decades, the university system has experienced huge growth, facing several challenges. Accordingly, the University of Pisa recognizes the value and opportunities deriving from research and fully supports collaboration with the world of entrepreneurship and industry, as well as local communities. Study programs, teaching methods and technologies, learning environments, quality assurance, programmed student numbers, and research results are key features of the prestige of the scientific community. Aim: In this respect, “Sport and Anatomy”, a brand that includes an academic organization at the University of Pisa, holds two main goals: (i) to offer the top level in both educational and professional fields; and (ii) to optimize the fine-tuning among all these sections, thus becoming a reference point for sports management. Methods and results: Indispensable links between basic and specialist sciences through different Masters’ and schools were created. In addition to didactic activity, research activity, medical assistance, and rehabilitation were coordinated. Two main outcomes emerged from this experience: (i) improved stakeholder performances and (ii) optimized cooperation between university and local communities. Conclusions: “Sport and Anatomy” plays a key role in supervising and accomplishing in an innovative way all the three missions of the university (i.e., teaching, research, and dissemination of knowledge), thus strongly fulfilling the aims of modern university targets
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
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