1,721,238 research outputs found
Work-up of male infertility
No full textMany health conditions can affect male fertility, thus highlighting the need for a thorough evaluation of patients to identify treatable or reversible lifestyle factors or medical conditions. The initial step in evaluating infertility is obtaining a thorough medical and reproductive history, with specific focus on health comorbidities and lifestyle factors. A comprehensive physical examination is compulsory in the evaluation of every infertile male, including presence of adequate secondary sexual characteristics. Semen analysis, as for World Health Organization recommendations, is the cornerstone for evaluating male infertility. However, more complex testing than semen analysis may be required in particular cases. In men with oligozoospermia or azoospermia a hormonal evaluation should be performed, at least including total testosterone, follicle stimulating hormone, and luteinizing hormone. Genetic testing should be offered to azoospermic men and those with severe oligozoospermia. Ultrasound of the genitourinary tract can enrich the physical examination in many cases
Gonadotropin Treatment For The Male Hypogonadotropic Hypogonadism
No full textHypogonadotropic hypogonadism (HH) is caused by a dysfunction in the hypothalamus and/or the pituitary gland and it can be congenital or acquired. This condition is biochemically characterized by low or inap-propriately normal gonadotropin levels along with low total testosterone levels. If fertility is not an issue, testosterone therapy is the treatment of choice to induce and maintain secondary sexual characteristics and sexual func-tion. Spermatogenesis is frequently impaired in patients with HH, but usually responsive to hormonal therapy such as gonadotropin therapy or GnRH supplementary/replacement therapy. When gonadotropins are the choice of treatment, conventional therapy includes human chorionic gonadotropin (hCG) along with different FSH for-mulations: human menopausal gonadotropins (hMG), highly purified urinary FSH preparations (hpFSH) (e.g., urofollitropin) or recombinant FSH (rFSH). The combination of FSH and hCG demonstrated to be associated with better outcomes than single compounds, whereas similar results were obtained with different FSH preparations in male individuals; both regarding the ability to stimulate spermatogenesis and eventually inducing physiology pregnancy. Gonadotropins can be administered either subcutaneously or intramuscularly. The combination therapy with hCG and FSH for a period of 12-24 months was found to promote testicular growth in almost all patients, spermatogenesis in approximately 80% and pregnancy rates in the range of 50%. Gynecomastia is the most common side effect of gonadotropin therapy and is due to hCG stimulation of aromatase causing increased secretion of estradiol. The therapeutic success is higher in patients with post-pubertal HH, in those without previ-ously undescended testes, in patients with higher baseline testicular volume, who underwent repeated cycles of therapy and in patients with higher baseline inhibin B serum concentrations. Reversal of hypogonadism can occur in up to 10% of patients but its physiopathologic mechanism has yet to be elucidated. In conclusion, gonadotropin therapy is effective in promoting puberty and in supporting spermatogenesis onset and preservation in HH patients with either hypothalamic or pituitary conditions
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
Phase diagram and superconductivity of calcium borohyrides at extreme pressures
Full text linkMotivated by the recent discovery of near-room temperature superconductivity in high-pressure superhydrides, we investigate from first principles the high-pressure superconducting phase diagram of the ternary Ca-B-H system, using ab initio evolutionary crystal structure prediction, and Density Functional Perturbation Theory. We find that below 100 GPa all stable and weakly metastable phases are insulating. This pressure marks the appearance of several new chemically-forbidden phases on the hull of stability, and the first onset of metalization in CaBH5. Metallization is then gradually achieved at higher pressure at different compositions. Among the metallic phases stable in the Megabar regime, we predict two high-Tc superconducting phases with CaBH6 and Ca2B2H13 compositions, with critical temperatures of 119 and 89 K at 300 GPa, respectively, surviving to lower pressures. Ternary hydrides will most likely play a major role in superconductivity research in the coming years; our study suggests that, in order to reduce the pressure for the onset of metallicity and superconductivity, further explorations of ternary hydrides should focus on elements less electronegative than boron
Breast cancer and genetics
No full textFamiliar aggregation of breast cancer has been known since Roman times, but it has been discussed in practical terms only from the 19th century. Most of the studies dealing with this issue suggest that the risk is higher in relatives of patients with early onset and that the risk also increases as a function of the bilaterality of the disease or the simultaneous presence of breast cancer and ovarian cancer. A series of epidemiological studies consistently suggest hereditary autosomal dominant transmission with reduced penetrance. Previous epidemiological research and collection of data from families has been used only from the 1990s in order to identify disease genes. The BRCA1 gene was identified as the first gene responsible for hereditary forms of breast cancer and subsequently BRCA2. In 1995 both genes were identified and cloned, and they demonstrated to have only minimal homology. The conclusions deal with genetic counseling and the evaluation of the risk of developing cancer
Conventional/unconventional superconductivity in high-pressure hydrides and beyond: insights from theory and perspectives
Full text linkThe observation of a superconducting critical temperature Tc exceeding 200K in ultra-dense hydrogen sulfide has demonstrated that high-Tc superconductivity can be achieved also in compounds where the superconducting pairing is mediated by phonons. This poses interesting challenges and opportunities. In particular, in this paper, we present a theoretical overview of the following points:Density functional theory has been quite effective in predicting various structures and this was the first time that theory has been successful in predicting novel superconductors. Along this line, we use DFT and many body theory to discuss possible strategies to search for new high-Tc superconductors in light-element compounds at high pressures [20, 34, 36, 37, 43].The microscopic key elements for high Tc seem to be a high phonon frequency, a peak in the density of states, a large el-ph coupling due to strong bonds, and the avoidance of lattice instabilities for very large couplings. The first two points lead to an appreciable Migdal parameter and to the possibility that non-adiabatic effects may require the generalization of the standard Migdal–Eliashberg theory of superconductivity [32, 33, 45].In this perspective, it would be important to locate these materials in the Uemura diagram and to measure isotope effect for Tc but also for the effective electron mass and the magnetic susceptibility [31], where the standard ME theory would give zero effect.The possibility of going beyond ME theory adds a new dimension also in the perspective of exporting these concepts to other materials at ambient or low pressure. For example, carbon compounds have a phonon frequency similar to the hydrides and the coupling can also be strong. This points to a search towards fullerene, graphene, or doped graphane. In these materials, especially fullerene, the Fermi energy is very small and the system is certainly in the non-adiabatic regime [31–33, 45]
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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