1,269 research outputs found
Timesharing performance as an indicator of pilot mental workload
Attentional deficits (workloads) were evaluated in a timesharing task. The results from this and other experiments were incorporated into an expert system designed to provide workload metric selection advice to non-experts in the field interested in operator workload
Human chorionic gonadotropin administration is associated with high pregnancy rates during ovarian stimulation and timed intercourse or intrauterine insemination
Abstract
Background
There are different factors that influence treatment outcome after ovarian stimulation and timed-intercourse or intrauterine insemination (IUI). After patient age, it has been suggested that timing of insemination in relation to ovulation is probably the most important variable affecting the success of treatment. The objective of this study is to study the value of human chorionic gonadotropin (hCG) administration and occurrence of luteinizing hormone (LH) surge in timing insemination on the treatment outcome after follicular monitoring with timed-intercourse or intrauterine insemination, with or without ovarian stimulation.
Methods
Retrospective analysis of 2000 consecutive completed treatment cycles (637 timed-intercourse and 1363 intrauterine insemination cycles). Stimulation protocols included clomiphene alone or with FSH injection, letrozole (an aromatase inhibitor) alone or with FSH, and FSH alone. LH-surge was defined as an increase in LH level ≥200% over mean of preceding two days. When given, hCG was administered at a dose of 10,000 IU. The main outcome was clinical pregnancy rate per cycle.
Results
Higher pregnancy rates occurred in cycles in which hCG was given. Occurrence of an LH-surge was associated with a higher pregnancy rate with clomiphene treatment, but a lower pregnancy rate with FSH treatment.
Conclusions
hCG administration is associated with a favorable outcome during ovarian stimulation. Awaiting occurrence of LH-surge is associated with a better outcome with CC but not with FSH treatment
The role of aromatase inhibitors in ameliorating deleterious effects of ovarian stimulation on outcome of infertility treatment
Clinical utilization of ovulation stimulation to facilitate the ability of a couple to conceive has not only provided a valuable therapeutic approach, but has also yielded extensive information on the physiology of ovarian follicular recruitment, endometrial receptivity and early embryo competency. One of the consequences of the use of fertility enhancing agents for ovarian stimulation has been the creation of a hyperestrogenic state, which may influence each of these parameters. Use of aromatase inhibitors reduces hyperestrogenism inevitably attained during ovarian stimulation. In addition, the adjunct use of aromatase inhibitors during ovarian stimulation reduces amount of gonadotropins required for optimum stimulation. The unique approach of reducing hyperestrogenism, as well as lowering amount of gonadotropins without affecting the number of mature ovarian follicles is an exciting strategy that could result in improvement in the treatment outcome by ameliorating the deleterious effects of the ovarian stimulation on follicular development, endometrial receptivity, as well as oocyte and embryo quality
Formation of Black Holes from Collapsed Cosmic String Loops
The fraction of cosmic string loops which collapse to form black holes is
estimated using a set of realistic loops generated by loop fragmentation. The
smallest radius sphere into which each cosmic string loop may fit is obtained
by monitoring the loop through one period of oscillation. For a loop with
invariant length which contracts to within a sphere of radius , the
minimum mass-per-unit length necessary for the cosmic string
loop to form a black hole according to the hoop conjecture is . Analyzing loops, we obtain the empirical estimate for the fraction of cosmic string
loops which collapse to form black holes as a function of the mass-per-unit
length in the range . We
use this power law to extrapolate to , obtaining the
fraction of physically interesting cosmic string loops which
collapse to form black holes within one oscillation period of formation.
Comparing this fraction with the observational bounds on a population of
evaporating black holes, we obtain the limit on the cosmic string mass-per-unit-length. This limit is consistent
with all other observational bounds.Comment: uuencoded, compressed postscript; 20 pages including 7 figure
Hormonal, follicular and endometrial dynamics in letrozole-treated versus natural cycles in patients undergoing controlled ovarian stimulation
The objective of this study was to compare letrozole-stimulated cycles to natural cycles in 208 patients undergoing intrauterine insemination (IUI) between July of 2004 and January of 2007. Group I (n = 47) received cycle monitoring only (natural group), Group II (n = 125) received letrozole 2.5 mg/day on cycle days three to seven, and Group III (n = 36) received letrozole 5 mg/day on cycle days three to seven. There were no differences between the groups in endometrial thickness or P4 on the day of hCG. Estradiol levels had higher variation in the second half of the follicular phase in both letrozole-treated groups compared to the control group. Estradiol per preovulatory follicle was similar in both letrozole cycles to that observed in the natural cycles. LH was lower on the day of hCG administration in the letrozole 2.5 mg/day group vs. the natural group. In summary, letrozole results in some minor changes in follicular, hormonal and endometrial dynamics compared to natural cycles. Increased folliculogenesis and pregnancy rates were observed in the letrozole-treated groups compared to the natural group. These findings need to be confirmed in larger, prospective studies
Polymorphic Variation of Genes in the Fibrinolytic System and the Risk of Ovarian Cancer
INTRODUCTION: The etiology of ovarian cancer is largely unknown. One hypothesis is that the inefficient removal of the blood clots and fibrin products which are deposited in the vicinity of the ovary by retrograde menstruation might be associated with an increased risk of ovarian cancer. Several single nucleotide polymorphisms within genes which comprise the fibrinolytic system have been shown to have functional effects on the rate of blood clot degradation. These were considered to be candidate genes in the present study. AIM: We studied the genotype distributions of 12 functional SNPs of four genes (tPA, uPA PAI1 and TAFI) among 775 ovarian cancer cases and 889 controls. RESULTS: No significant associations were seen between any of the ten SNPs and the risk of ovarian cancer as a whole, or in any histologic subgroup. DISCUSSION: Germline known functional variants of genes in the fibrinolytic system are not associated with risk of ovarian cancer
Why every observatory needs a disco ball
Commercial disco balls provide a safe, effective and instructive way of
observing the Sun. We explore the optics of solar projections with disco balls,
and find that while sunspot observations are challenging, the solar disk and
its changes during eclipses are easy and fun to observe. We explore the disco
ball's potential for observing the moon and other bright astronomical
phenomena.Comment: 6 pages, 7 figures. Submitted to Physics Education. Comments welcom
Cliophysics: Socio-political Reliability Theory, Polity Duration and African Political (In)stabilities
Quantification of historical sociological processes have recently gained
attention among theoreticians in the effort of providing a solid theoretical
understanding of the behaviors and regularities present in sociopolitical
dynamics. Here we present a reliability theory of polity processes with
emphases on individual political dynamics of African countries. We found that
the structural properties of polity failure rates successfully capture the risk
of political vulnerability and instabilities in which 87.50%, 75%, 71.43%, and
0% of the countries with monotonically increasing, unimodal, U-shaped and
monotonically decreasing polity failure rates, respectively, have high level of
state fragility indices. The quasi-U-shape relationship between average polity
duration and regime types corroborates historical precedents and explains the
stability of the autocracies and democracies.Comment: 4 pages, 3 figures, 1 tabl
The Benefits and Challenges of Preconsent in a Multisite, Pediatric Sickle Cell Intervention Trial
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133619/1/pbc26013.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133619/2/pbc26013_am.pd
HTLV-III Serology in Hemophilia: Relationship with Immunologic Abnormalities
We investigated the relationship of the presence of antibodies to HTLV-III and immunologic abnormalities in patients with hemophilia. Serum antibodies to HTLV-III were analyzed by ELISA assay, immunoprecipitation of labeled cell extracts, and immunoprecipitation of purified HTLV-III p24. Thirty-four (61%) of the total group (n = 56) had antibody to HTLV-III; 34 (76%) of 45 patients given commercial factor VIII preparations were seropositive, compared with none of 11 patients treated exclusively with cryoprecipitate obtained from volunteer blood donors. Of patients who were seropositive for HTLV-III antibody, 94% had abnormal T4/T8 ratios, and 33% of those whose serum was antibody negative had abnormal T4/T8 ratios; five patients, each antibody positive, have lymphadenopathy syndrome. Sequential studies in a subset of patients indicate that there is a changing pattern of antibody production to HTLV-III antigens after seroconversion
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