13 research outputs found
Thermodynamical properties of hairy black holes in n spacetimes dimensions
The issue concerning the existence of exact black hole solutions in presence
of non vanishing cosmological constant and scalar fields is reconsidered. With
regard to this, in investigating no-hair theorem violations, exact solutions of
gravity having as a source an interacting and conformally coupled scalar field
are revisited in arbitrary dimensional non asymptotically flat space-times. New
and known hairy black hole solutions are discussed. The thermodynamical
properties associated with these solutions are investigated and the invariance
of the black hole entropy with respect to different conformal frames is proven.Comment: Latex document, 23 pages, references added to section [1] and [3],
typos correcte
Variation of DNA Fragmentation Levels During Density Gradient Sperm Selection for Assisted Reproduction Techniques: A Possible New Male Predictive Parameter of Pregnancy?
Predicting the outcome of in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) is one main goal of the present research on assisted reproduction. To understand whether density gradient centrifugation (DGC), used to select sperm, can affect sperm DNA integrity and impact pregnancy rate (PR), we prospectively evaluated sperm DNA fragmentation (sDF) by TUNEL/PI, before and after DGC. sDF was studied in a cohort of 90 infertile couples the same day of IVF/ICSI treatment. After DGC, sDF increased in 41 samples (Group A, median sDF value: 29.25% [interquartile range, IQR: 16.01–41.63] in pre- and 60.40% [IQR: 32.92–93.53] in post-DGC) and decreased in 49 (Group B, median sDF value: 18.84% [IQR: 13.70–35.47] in pre- and 8.98% [IQR: 6.24–15.58] in post-DGC). PR was 17.1% and 34.4% in Group A and B, respectively (odds ratio [OR]: 2.58, 95% confidence interval [CI]: 0.95–7.04, P = 0.056). After adjustment for female factor, female and male age and female BMI, the estimated OR increased to 3.12 (95% CI: 1.05–9.27, P = 0.041). According to the subgroup analysis for presence/absence of female factor, heterogeneity in the association between the Group A and B and PR emerged (OR: 4.22, 95% CI: 1.16–15.30 and OR: 1.53, 95% CI: 0.23–10.40, respectively, for couples without, n = 59, and with, n = 31, female factor). This study provides the first evidence that the DGC procedure produces an increase in sDF in about half of the subjects undergoing IVF/ICSI, who then show a much lower probability of pregnancy, raising concerns about the safety of this selection procedure. Evaluation of sDF before and after DGC configures as a possible new prognostic parameter of pregnancy outcome in IVF/ICSI. Alternative sperm selection strategies are recommended for those subjects who undergo the damage after DGC
Hawking Radiation as Tunneling for Extremal and Rotating Black Holes
The issue concerning semi-classical methods recently developed in deriving
the conditions for Hawking radiation as tunneling, is revisited and applied
also to rotating black hole solutions as well as to the extremal cases. It is
noticed how the tunneling method fixes the temperature of extremal black hole
to be zero, unlike the Euclidean regularity method that allows an arbitrary
compactification period. A comparison with other approaches is presented.Comment: 17 pages, Latex document, typos corrected, four more references,
improved discussion in section
Hamilton-Jacobi Tunneling Method for Dynamical Horizons in Different Coordinate Gauges
Previous work on dynamical black hole instability is further elucidated
within the Hamilton-Jacobi method for horizon tunneling and the reconstruction
of the classical action by means of the null-expansion method. Everything is
based on two natural requirements, namely that the tunneling rate is an
observable and therefore it must be based on invariantly defined quantities,
and that coordinate systems which do not cover the horizon should not be
admitted. These simple observations can help to clarify some ambiguities, like
the doubling of the temperature occurring in the static case when using
singular coordinates, and the role, if any, of the temporal contribution of the
action to the emission rate. The formalism is also applied to FRW cosmological
models, where it is observed that it predicts the positivity of the temperature
naturally, without further assumptions on the sign of the energy.Comment: Standard Latex document, typos corrected, refined discussion of
tunneling picture, subsection 5.1 remove
Efficacy of the motile sperm organelle morphology examination (MSOME) in predicting pregnancy after intrauterine insemination
Background: Although the motile sperm organelle morphology examination (MSOME) was developed merely as a selection criterion, its application as a method for classifying sperm morphology may represent an improvement in the evaluation of semen quality. The aim of this study was to determine the prognostic value of normal sperm morphology using MSOME with regard to clinical pregnancy (CP) after intrauterine insemination (IUI).Methods: A total of 156 IUI cycles that were performed in 111 couples were prospectively analysed. Each subject received 75 IU of recombinant FSH every second day from the third day of the cycle. Beginning on the 10th day of the cycle, follicular development was monitored by vaginal ultrasound. When one or two follicles measuring at least 17 mm were observed, recombinant hCG was administered, and IUI was performed 12-14 h and 36-40 h after hCG treatment. Prior to the IUI procedure, sperm samples were analysed by MSOME at 8400x magnification using an inverted microscope that was equipped with DIC/Nomarski differential interference contrast optics. A minimum of 200 motile spermatozoa per semen sample were evaluated, and the percentage of normal spermatozoa in each sample was determined.Results: Pregnancy occurred in 34 IUI cycles (CP rate per cycle: 21.8%, per patient: 30.6%). Based on the MSOME criteria, a significantly higher percentage of normal spermatozoa was found in the group of men in which the IUI cycles resulted in pregnancy (2.6+/-3.1%) compared to the group that did not achieve pregnancy (1.2+/-1.7%; P = 0.019). Logistic regression showed that the percentage of normal cells in the MSOME was a determining factor for the likelihood of clinical pregnancy (OR: 1.28; 95% CI: 1.08 to 1.51; P = 0.003). The ROC curve revealed an area under the curve of 0.63 and an optimum cut-off point of 2% of normal sperm morphology. At this cut-off threshold, using the percentage of normal sperm morphology by MSOME to predict pregnancy was 50% sensitive with a 40% positive predictive value and 79% specificity with an 85% negative predictive value. The efficacy of using the percentage of normal sperm morphology by MSOME in predicting pregnancy was 65%.Conclusions: The present findings support the use of high-magnification microscopy both for selecting spermatozoa and as a routine method for analysing semen before performing IUI