1,721,004 research outputs found
Chromosomal and functional characterization of the early stages of human embryogenesis
Full text linkThe main objective of modern IVF is to maximize the effectiveness of the times to achieve a pregnancy and at the same time also manage the risks, looking for new predictive parameters of the embryonic developmental competence. The analysis of embryo morphodynamic growth is not associated with its euploidy or implantation competence. However, some static parameters of embryo quality might exist that could be associated with embryo competence beyond its chromosomal constitution. The aims of this project are: i) To study from a morphodynamic, genetic and clinical point of view, embryos that show an abnormal development during preimplantation growth, in particular, the exclusion of cells (ExC) from embryonic mass at the moment of morulation. ii) Trying to understand if the morphodynamic characterization of euploid blastocyst development allows a higher prediction of live-birth (LB) after single-embryo-transfers (SET). For both the aims set in this Ph.D. project, preimplantation development and morphodynamic growth of embryos were observed in a time-lapse culture system (Embryoscope, Vitrolife). For the first aim, our preliminary data show that the exclusion of cells from the body of the blastocyst could be not-intuitively associated to a higher competence resulting from the embryonic capacity to overcome an abnormal cleavage pattern occurred in the very first divisions before the activation of the embryonic genome (4 to 8cell stage in humans). It is exciting the future perspective of collecting the ExC aiming at analyzing them through the karyomapping technology as well as biochemical assays, to better describe both the chromosomal segregation and the cellular physiology. For the second aim, we have divided the study into two phases in collaboration with 3 IVF Centers. In phase1, 511 first euploid SETs from 1069 patients undergoing preimplantation-genetic-testing-for-aneuploidies (PGT-A) cycles at 2 IVF centers were investigated (training set). All embryos were cultured in a specific time-lapse incubator with continuous media. The data from the time of polar-body-extrusion to time starting-blastulation were collected. Trophectoderm (TE) and inner-cell-mass (ICM) static morphology were also assessed. Logistic regressions were conducted to outline a predictive model of LB, whose power was estimated through a ROC-curve. In phase2, this model was tested in an independent dataset of 319 consecutive SETs from 546 PGT-A cycles at 3 IVF centers (validation set). The average LB-rate in the training set was 40% (N=207/511). Only time-of-morulation (tM) and trophectoderm quality were outlined as putative predictors of LB at both centers. The model showed a significant AUC (area under the curve) of 0.65. In the validation set, the euploid blastocysts characterized by tM<80hr and high-quality trophectoderm resulted in an LB-rate of 55.2% (n=37/67), while those with tM≥80hr and a low-quality trophectoderm resulted in an LB-rate of 25.5% (N=13/51;p<0.01). The ROC-curve analysis pictured an AUC of 0.6. A model including tM and trophectoderm quality involves a better prediction of euploid blastocyst reproductive competence. This model was reproducible across different centers under specific culture conditions. These data support the crucial role of morulation for embryo development, a stage that involves massive morphological, cellular and molecular changes requiring more investigations. Moreover, important guidelines for IVF laboratories that do not conduct a time-lapse-based embryo culture may arise from these two studies
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Patient Autonomy, Physician Obligation, and State Licensing Authority in The Constitutional Right Not to Kill: A Response to Professor Mark L. Rienzi
No full textIn his article, The Constitutional Right Not to Kill, Professor Mark L. Rienzi persuasively asserts that the Fifth and Fourteenth Amendments protect individuals from being forced to participate in government-authorized killings. Drawing from several strands of diverse legal doctrines, including military conscientious objections, capital punishment, physician-assisted death, abortion, and self-defense, he demonstrates the various ways in which the state and federal governments have shielded American citizens from being required to kill against their will
Patient Autonomy, Physician Obligation, and State Licensing Authority in The Constitutional Right Not to Kill: A Response to Professor Mark L. Rienzi
Full text linkIn his article, The Constitutional Right Not to Kill, Professor Mark L. Rienzi persuasively asserts that the Fifth and Fourteenth Amendments protect individuals from being forced to participate in government-authorized killings. Drawing from several strands of diverse legal doctrines, including military conscientious objections, capital punishment, physician-assisted death, abortion, and self-defense, he demonstrates the various ways in which the state and federal governments have shielded American citizens from being required to kill against their will
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
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