5,186 research outputs found

    Universal Properties of Galactic Rotation Curves and a First Principles Derivation of the Tully-Fisher Relation

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    In a recent paper McGaugh, Lelli, and Schombert showed that in an empirical plot of the observed centripetal accelerations in spiral galaxies against those predicted by the Newtonian gravity of the luminous matter in those galaxies the data points occupied a remarkably narrow band. While one could summarize the mean properties of the band by drawing a single mean curve through it, by fitting the band with the illustrative conformal gravity theory with fits that fill out the width of the band we show here that the width of the band is just as physically significant. We show that at very low luminous Newtonian accelerations the plot can become independent of the luminous Newtonian contribution altogether, but still be non-trivial due to the contribution of matter outside of the galaxies (viz. the rest of the visible universe). We present a new empirical plot of the difference between the observed centripetal accelerations and the luminous Newtonian expectations as a function of distance from the centers of galaxies, and show that at distances greater than 10 kpc the plot also occupies a remarkably narrow band, one even close to constant. Using the conformal gravity theory we provide a first principles derivation of the empirical Tully-Fisher relation.Comment: 6 pages, 15 figures. The paper is a comment on S. S. McGaugh, F. Lelli, and J. M. Schombert, Phys. Rev. Lett. 117, 201101 (2016). Updated to include a first principles derivation of the Tully-Fisher relation using the conformal gravity theory. Submitted to Physics Letters

    Analisi Morfometrica dei Cromosomi del Coniglio (Oryctolagus Cuniculus L.)

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    RIASSUNTOSono stati studiati i cromosomi di coniglio (Oryctolagus cuniculus L.).Il numero diploide dei cromosomi in cellule somatiche e risultato di 2 n= 44. L'analisi morfologica e metrica di essi ha permesso la distinzione in gruppi di cromosomi affini. Una tale classificazione si pensa possa essere utile in ricerche di cariologia comparata nell'ambito dei Leporidae

    Urinary incontinence, work, and intention to leave current job: A cross sectional survey of the Australian nursing and midwifery workforce

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    © 2017 Wiley Periodicals, Inc. Aims: To determine the prevalence and severity of urinary incontinence (UI) in a group of female nurses and midwives, and to examine the relationship between UI, work and intention to leave current job. Methods: An electronic survey “Fit for the future” was distributed to nurses and midwives in NSW, Australia between May 2014 and February 2015. UI was investigated using the International Consultation on Incontinence UI—Short Form. Examined work characteristics included: work role, location, setting, contract, shift, job satisfaction, and plans to leave current job. Logistic regression modelling was performed to determine whether the severity of UI had an independent effect on intention to leave. Results: Of 5041 survey responses, 68.5% answered the question on urine leakage. Of the included female sample (n = 2,907) the prevalence of UI was 32.0% (95% CI: 30-34%): of these 40.5% experienced moderate and 4.4% “severe or very severe” symptoms. UI was more likely to be reported in nurses or midwives working part-time or days only (not shifts). Those with “severe or very severe UI” were more likely to indicate an intention to leave at 12 months (OR: 2.68; 95% CI: 1.18-6.06) than those with slight or moderate symptoms, after accounting for age, body mass index, parity, pelvic organ prolapse, anxiety, depression, work contract, shift, and job satisfaction. Conclusions: UI is a condition of high prevalence and significant severity in female nurses and midwives. In this workforce, severe UI was associated with intentions related to future employment

    APOPTOTIC ANALYSIS OF CUMULUS CELLS FOR THE SELECTION OF COMPETENT OOCYTES TO BE FERTILIZED BY INTRACYTOPLASMIC SPERM INJECTION (ICSI)

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    Oocyte quality is one of the main factors for the success of in vitro fertilization protocols. Apoptosis is known to affect oocyte quality and may impair subsequent embryonic development and implantation. The aim of this study was to investigate the apoptosis rate of single and pooled cumulus cells of cumulus cell\u2013oocyte complexes (COCs), as markers of oocyte quality, prior to intracytoplasmatic sperm injection (ICSI).We investigated the apoptosis rate by TUNEL assay (DNA fragmentation) and caspase-3 immunoassay of single and pooled cumulus cells of COCs. The results showed that DNA fragmentation in cumulus cells was remarkably lower in patients who achieved a pregnancy than in those who did not. Cumulus cell apoptosis rate could be a marker for the selection of the best oocytes to be fertilized by intracytoplasmatic sperm injection

    Autophagy as a defense strategy against stress: focus on Paracentrotus lividus sea urchin embryos exposed to cadmium

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    Autophagy is used by organisms as a defense strategy to face environmental stress. This mechanism has been described as one of the most important intracellular pathways responsible for the degradation and recycling of proteins and organelles. It can act as a cell survival mechanism if the cellular damage is not too extensive or as a cell death mechanism if the damage/stress is irreversible; in the latter case, it can operate as an independent pathway or together with the apoptotic one. In this review, we discuss the autophagic process activated in several aquatic organisms exposed to different types of environmental stressors, focusing on the sea urchin embryo, a suitable system recently included into the guidelines for the use and interpretation of assays to monitor autophagy. After cadmium (Cd) exposure, a heavy metal recognized as an environmental toxicant, the sea urchin embryo is able to adopt different defense mechanisms, in a hierarchical way. Among these, autophagy is one of the main responses activated to preserve the developmental program. Finally, we discuss the interplay between autophagy and apoptosis in the sea urchin embryo, a temporal and functional choice that depends on the intensity of stress conditions

    The Role of Autophagy and Apoptosis During Embryo Development

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    Programmed cell death (PCD) and cell survival are two sides of the same coin. Autophagy and apoptosis are crucial processes during embryo development of Invertebrates and Vertebrates organisms, as they are necessary for the formation of a new organism, starting from a fertilized egg. Fertilization triggers cell remodeling from each gamete to a totipotent zygote. During embryogenesis, the cells undergo various processes, thus allowing the transformation of the embryo into an adult organism. In particular, cells require the appropriate tools to suddenly modify their morphology and protein content in order to respond to intrinsic and external stimuli. Autophagy and apoptosis are involved in cell proliferation, differentiation and morphogenesis. Programmed cell death is a key physiological mechanism that ensures the correct development and the maintenance of tissues and organs homeostasis in multicellular organisms. PCD has been classified into three types, according to the morphology that the dying cells acquire and the molecular machinery involved: PCD type I or apoptosis; PCD type II or autophagy and PCD type III or necrosis (not involved in physiological development). These different types of cell death have specific features that can be used to be identified and characterized. Apoptosis is a highly conserved, genetically-controlled process through which certain cells destroy themselves. Autophagy is an evolutionarily conserved pathway used by eukaryotes for degrading and recycling various cellular constituents, such as long-lived proteins and entire organelles, that was mainly detected in those tissues where abundant cell death is required. Both autophagy and apoptosis are induced under stress conditions as an adaptive response against stress. Usually, environmental stress cause severe effects on embryonic development. Embryos of different species, exposed to different types of physical or chemical stress, temporarily suspend their development and activate several protective strategies, including PCD II and PCD III. Research has yet to elucidate the interplay between these key processes. Not all types of PCD are always detected in association with a developmental process. Unlike the degeneration of tissues of some invertebrates, the tissues of vertebrates undergo PCD preferentially through an apoptotic mechanisms. In this chapter, we will briefly describe some specific features of apoptotic and autophagic processes. We will focus our attention in some useful model systems of invertebrates and vertebrates organisms, where autophagy and apoptosis occur both in physiological and stress conditions; specifically, we will analyze embryos of: the nematode Caenorhabditis elegans, the insect Drosophila melanogaster, the sea urchin Paracentrotus lividus, the fish Danio Rerio, the mouse mammalian model, and finally we will consider the differentiation of the male and female embryonic germlines in humans

    APOPTOSIS RATE IN CUMULUS CELLS AS POSSIBLE MOLECULAR BIOMARKER FOR OOCYTE COMPETENCE.

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    Several lines of evidence showed that apoptosis rate of cumulus cells in oocytes derived by assisted reproductive technologies could be used as an indicator of fertilizing gamete quality. Aim of the study was to investigate the effects of three different ovarian stimulation protocols on the biological and clinical outcome in hyporesponder patients. Collected data showed a higher significant rate of DNA fragmentation index (DFI) in U group (patients treated with Highly Purified human Menopausal Gonadotrophin) than in P group (treated with recombinant human Follicle Stimulating Hormone (r-hFSH) combined with recombinant human Luteinizing Hormone (r-hLH)). Both groups R (treated with r-hFSH alone) and P showed a significant increase in collected and fertilized oocytes number, embryo quality number. This study showed that combined r-hFSH/r-hLH therapy could represent the best pharmacological strategy for controlled ovarian stimulation and suggests to use DFI as a biomarker of ovarian function in hyporesponder patients
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