520 research outputs found
Miscarriage rates after dehydroepiandrosterone (DHEA) supplementation in women with diminished ovarian reserve: a case control study
<p>Abstract</p> <p>Background</p> <p>Dehydroepinadrosterone (DHEA) supplementation improves pregnancy chances in women with diminished ovarian reserve (DOR), by possibly reducing aneuploidy. Since a large majority of spontaneous miscarriages are associated with aneuploidy, one can speculate that DHEA supplementation may also reduce miscarriage rates.</p> <p>Methods</p> <p>We retroactively compared, utilizing two independent statistical models, miscarriage rates in 73 DHEA supplemented pregnancies at two independent North American infertility centers, age-stratified, to miscarriages reported in a national U.S. in vitro fertilization (IVF) data base.</p> <p>Results</p> <p>After DHEA supplementation the miscarriage rate at both centers was 15.1% (15.0% and 15.2%, respectively). For DHEA supplementation Mantel-Hänszel common odds ratio (and 95% confidence interval), stratified by age, was significantly lower, relative to odds of miscarriage in the general IVF control population [0.49 (0.25-0.94; p = 0.04)]. Miscarriage rates after DHEA were significantly lower at all ages but most pronounced above age 35 years.</p> <p>Discussion</p> <p>Since DOR patients in the literature are reported to experience significantly higher miscarriage rates than average IVF patients, the here observed reduction in miscarriages after DHEA supplementation exceeds, however, all expectations. Miscarriage rates after DHEA not only were lower than in an average national IVF population but were comparable to rates reported in normally fertile populations. Low miscarriage rates, comparable to those of normal fertile women, are statistically impossible to achieve in DOR patients without assumption of a DHEA effect on embryo ploidy. Beyond further investigations in infertile populations, these data, therefore, also suggest the investigations of pre-conception DHEA supplementation in normal fertile populations above age 35 years.</p
Follicle Stimulating Hormone and Anti-Müllerian Hormone per Oocyte in Predicting in vitro Fertilization Pregnancy in High Responders: A Cohort Study
Background: Follicle stimulating hormone (FSH) and Anti-Müllerian hormone (AMH) are utilized to differentiate between good and poor response to controlled ovarian hyperstimulation. Their respective roles in defining functional ovarian reserve remain, however, to be elucidated. To better understand those we investigated AMH and FSH per oocyte retrieved (AMHo and FSHo). Methodology/Principal Findings: Three-hundred and ninety-six women, undergoing first in vitro fertilization cycles, were retrospectively evaluated. Women with oocyte yields.75 th percentile for their age group were identified as high responders. In a series of logistic regression analyses, AMHo and FSHo levels were then evaluated as predictive factors for pregnancy potential in high responders. Patients presented with a mean age of 38.065.0 years, mean baseline FSH of 11.868.7 mIU/mL and mean AMH of 1.662.1 ng/mL. Those 88 women, who qualified as high responders, showed mean FSH of 9.766.5 mIU/mL, AMH of 3.163.1 ng/mL and oocyte yields of 15.867.1. Baseline FSH and AMH did not predict pregnancy in high responders. However, a statistically significant association between FSHo and pregnancy was observed in high responders, both after univariate regression (p = 0.02) and when adjusted for age, percentage of usable embryos, and number of embryos transferred (p = 0.03). Rate of useable embryos also significantly affected pregnancy outcome independently of FSHo (p = 0.01). AMHo was also associated with clinical pregnancy chances in high responders (p = 0.03
Karen Barad’s Quantum Ontology and Posthuman Ethics: Rethinking the Concept of Relationality
This article focuses on Karen Barad’s quantum ontology and her attempts to reformulate the concept of relationality. The aim is to show how Barad’s work articulates a new kind of empiricism for the social sciences, by reclaiming the creative and speculative force of experimental practice and by recentering the philosophical problem as a source of inquiry. Relationality is redefined through discussions of diffractive apparatus, more-than-human performativity, and the “polymorphous perversity” of the matter-meaning mixture
FMR1 Genotype with Autoimmunity-Associated Polycystic Ovary-Like Phenotype and Decreased Pregnancy Chance
The FMR1 gene partially appears to control ovarian reserve, with a specific ovarian sub-genotype statistically associated with a polycystic ovary (PCO)- like phenotype. Some forms of PCO have been associated with autoimmunity. We, therefore, investigated in multiple regression analyses associations of ovary-specific FMR1 genotypes with autoimmunity and pregnancy chances (with in vitro fertilization, IVF) in 339 consecutive infertile women (455 IVF cycles), 75 with PCO-like phenotype, adjusted for age, race/ethnicity, medication dosage and number of oocytes retrieved. Patients included 183 (54.0%) with normal (norm) and 156 (46%) with heterozygous (het) FMR1 genotypes; 133 (39.2%) demonstrated laboratory evidence of autoimmunity: 51.1% of het-norm/low, 38.3% of norm and 24.2% het-norm/high genotype and sub-genotypes demonstrated autoimmunity (p = 0.003). Prevalence of autoimmunity increased further in PCO-like phenotype patients with het-norm/low genotype (83.3%), remained unchanged with norm (34.0%) and decreased in het-norm/high women (10.0%; P<0.0001). Pregnancy rates were significantly higher with norm (38.6%) than het-norm/low (22.2%, p = 0.001). FMR1 sub-genotype het-norm/low is strongly associated with autoimmunity and decreased pregnancy chances in IVF, reaffirming the importance of the distal long arm of the X chromosome (FMR1 maps at Xq27.3) for autoimmunity, ovarian function and, likely, pregnancy chance with IVF
Rethinking the Poverty-disease Nexus: the Case of HIV/AIDS in South Africa
While it is well-established that poverty and disease are intimately connected, the nature of this connection and the role of poverty in disease causation remains contested in scientific and social studies of disease. Using the case of HIV/AIDS in South Africa and drawing on a theoretically grounded analysis, this paper reconceptualises disease and poverty as ontologically entangled. In the context of the South African HIV epidemic, this rethinking of the poverty-disease dynamic enables an account of how social forces such as poverty become embodied in the very substance of disease to produce ontologies of HIV/AIDS unique to South Africa
Pion structure from improved lattice QCD: form factor and charge radius at low masses
The charge form factor of the pion is calculated in lattice QCD. The
non-perturbatively improved Sheikholeslami-Wohlert action is used together with
the improved vector current. Other choices for the current are
examined. The form factor is extracted for pion masses from 970 MeV down to 360
MeV and for momentum transfers . The mean square
charge radius is extracted, compared to previous determinations and its
extrapolation to lower masses discussed.Comment: 12 pages REVTeX, 15 figures. Designation of currents clarified.
Details concerning extraction of parameters added. Version accepted by Phys.
Rev.
Reimagining quality in early childhood
This special issue brings together a collection of rich, complex and challenging contributions that attempt to offer generative approaches to reconfigure what might constitute ‘quality’ within early years education. The issue came about from a shared concern about what Moss (this issue) refers to as the ‘gravitational pull’ of quality in early childhood education; debates about quality have existed for a considerable time and, despite rigorous critique, remain resolute. This issue aims to revisit and extend the groundbreaking work undertaken by Gunilla Dahlberg, Peter Moss and Alan Pence (1999, 2007) in Beyond Quality in Early Childhood Education and Care: Postmodern Perspectives and in the subsequent revised edition. In both texts, the authors made the astute observation that the concept and language of quality cannot accommodate issues such as diversity and multiple perspectives, contextual specificity and subjectivity. They argue that we must ‘go beyond the concept of quality’ (Dahlberg et al., 2007: 6) and, in so doing, suggest working with a new concept: ‘meaning making’
Re-Generating Research Partnerships in Early Childhood Education: A Non-Idealized Vision
This chapter provides a challenge to positivist notions of partnership in early childhood education, and instead proposes a re-generative posthumanist perspective, based on relationality of partnerships. Specifically, the chapter addresses the troubles and struggles inherited in research partnerships through a non-idealized vision of research partnerships. It experiments with the notions of regenerating ‘change’ and regenerating ‘relationality’. It also addresses the multi-layered aspects of knowledge-in-the-making; non-innocent relations; difficulties of thinking change in research; and the potentialities of conflict and dissension. However, no certainties and closures about research partnerships are provided
The Strongly Coupled 't Hooft Model on the Lattice
We study the strong coupling limit of the one-flavor and two-flavor massless
't Hooft models, -color , on a lattice. We use
staggered fermions and the Hamiltonian approach to lattice gauge theories. We
show that the one-flavor model is effectively described by the
antiferromagnetic Ising model, whose ground state is the vacuum of the gauge
model in the infinite coupling limit; expanding around this ground state we
derive a strong coupling expansion and compute the lowest lying hadron masses
as well as the chiral condensate of the gauge theory. Our lattice computation
well reproduces the results of the continuum theory. Baryons are massless in
the infinite coupling limit; they acquire a mass already at the second order in
the strong coupling expansion in agreement with the Witten argument that
baryons are the solitons.
The spectrum and chiral condensate of the two-flavor model are effectively
described in terms of observables of the quantum antiferromagnetic Heisenberg
model. We explicitly write the lowest lying hadron masses and chiral condensate
in terms of spin-spin correlators on the ground state of the spin model. We
show that the planar limit () of the gauge
model corresponds to the large spin limit () of the
antiferromagnet and compute the hadron mass spectrum in this limit finding
that, also in this model, the pattern of chiral symmetry breaking of the
continuum theory is well reproduced on the lattice.Comment: LaTex, 25 pages, no figure
Transdisciplinarity: towards an epistemology of what matters
This chapter explores the adoption of a transdisciplinary approach to knowledge by a doctor of professional studies research programme at Middlesex University in London. This programme is designed for senior professionals in a range of sectors who wish to bring about change, of varying degrees of magnitude, in practices and attitudes in their contexts. Its research pedagogy combines professional and academic knowledge to meet challenges posed by the temporal limitations of rapidly shifting local and global contexts. It proposes that conceptualising practice, through a transdisciplinary lens, opens up significant possibilities for both articulating and navigating the complexities inherent in any cultural ecology and the positioning of the researcher in that context. This enhances the research process’s potency to influence attitudes, focus and impact including the concept of agential knowing in identifying and attending to what matters
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