9,648 research outputs found
Comparison of antimüllerian hormone levels and antral follicle count as predictor of ovarian response to controlled ovarian stimulation in good-prognosis patients at individual fertility clinics in two multicenter trials
Objective
To compare antimüllerian hormone (AMH) and antral follicle count (AFC) as predictors of ovarian response to controlled ovarian stimulation at individual fertility clinics.
Design
Retrospective analysis of individual study center data in two multicenter trials. Centers that provided >10 patients were included in the analysis.
Setting
A total of 19 (n = 519 patients) and 18 study centers (n = 686 patients) participating in a long GnRH agonist trial (MERIT) and a GnRH antagonist trial (MEGASET), respectively.
Patient(s)
Infertile women of good prognosis.
Intervention(s)
Long GnRH agonist or GnRH antagonist cycles.
Main Outcome Measure(s)
Correlation between AMH and AFC, and oocyte yield by each study center for each trial.
Results(s)
Antimüllerian hormone was more strongly correlated with oocyte yield than AFC: r = 0.56 vs. r = 0.28 in the GnRH agonist cohort, and r = 0.55 vs. r = 0.33 in the GnRH antagonist cohort. The correlation was numerically higher for AMH than for AFC at a significantly higher proportion of study centers: 17 (89%) and 15 (83%) centers in the long GnRH agonist and GnRH antagonist trial, respectively. Assessment of the relative capacity of AMH and AFC for predicting oocyte yield demonstrated that AMH dominated the model: AMH, R2 = 0.29 and 0.23; AFC: R2 = 0.07 and 0.07; AMH + AFC: R2 = 0.30 and 0.23 for long GnRH agonist and GnRH antagonist trials, respectively.
Conclusions(s)
Antimüllerian hormone was a stronger predictor of ovarian response to gonadotropin therapy than AFC at the study center level in both randomized trials utilizing GnRH agonist and GnRH antagonist protocols. Antral follicle count provided no added predictive value beyond AMH.</p
SMA and Spitzer Observations of Bok Glouble CB17: A Candidate First Hydrostatic Core?
We present high angular resolution SMA and Spitzer observations toward the
Bok globule CB17. SMA 1.3mm dust continuum images reveal within CB17 two
sources with an angular separation of about 21" (about 5250 AU at a distance of
250 pc). The northwestern continuum source, referred to as CB17 IRS, dominates
the infrared emission in the Spitzer images, drives a bipolar outflow extending
in the northwest-southeast direction, and is classified as a low luminosity
Class0/I transition object (L_bol ~ 0.5 L_sun). The southeastern continuum
source, referred to as CB17 MMS, has faint dust continuum emission in the SMA
1.3mm observations (about 6 sigma detection; ~3.8 mJy), but is not detected in
the deep Spitzer infrared images at wavelengths from 3.6 to 70 micron. Its
bolometric luminosity and temperature, estimated from its spectral energy
distribution, are less than 0.04 L_sun and 16 K, respectively. The SMA CO(2-1)
observations suggest that CB17 MMS may drive a low-velocity molecular outflow
(about 2.5 km/s), extending in the east-west direction. Comparisons with
prestellar cores and Class0 protostars suggest that CB17 MMS is more evolved
than prestellar cores but less evolved than Class0 protostars. The observed
characteristics of CB17 MMS are consistent with the theoretical predictions
from radiative/magneto hydrodynamical simulations of a first hydrostatic core,
but there is also the possibility that CB17 MMS is an extremely low luminosity
protostar deeply embedded in an edge-on circumstellar disk. Further
observations are needed to study the properties of CB17 MMS and to address more
precisely its evolutionary stage.Comment: 33 pages, 11 figures, to be published by Ap
Peasant enterprise and processes of monetisation in highland Peru: the case of pucara
The main theme of the thesis can be summarised as an attempt to explore some classical theoretical statementsabout the so-called 'progressive' character of commercial activities in the Highlands of Peru, and on the other hand,to examine certain methodological issues arising from earlier investigations in the area (see Arguedas, 1957; AlersMontalvo,1967; Adams, 1959; Long and Roberts, 1974, and 1978). In order to explore these two dimensions, the analysis concentrates upon determining the functions of small-scale commercial activities in a rural context, relating them to the existing agrarian structure, patterns of income distribution, consumption and diversification of economic activities at community level, and more systematically to processes of distribution and exchange at regional and national levels. The study focuses upon the role of rural, non-agricultural activities, a persisting feature of the Peruvian economy, which has provided the basis for the development of small-scale, economically dynamic entreprise that has, on the one hand impeded proletarianisation in the rural sector, and yeton the other, increased socio-economic differentiation. To understand this apparently contradictory dynamic, the nature of subordinated groups within the structure of underdevelopment is examined. It is argued that one must not consider such groups merely as a target for manipulation by capitalist interests, which has been the tendency of some writers from both the modernisation and dependency schools. Indeed, these subordinated groups (consisting in the rural sector of small-scale agriculturalists and traders etc.) have throughout much of the history of Peru has been placed outside the principal lines of development strategy adopted by the State and external interests. A sounder interpretation rests, I believe, upon a systematic analysis of the economic and social functions of small-scale enterprise, which, given the weakness of Peruvian capitalism, assumes a complementary dynamic which in certain important ways counterbalances the penetration of the capitalist mode of production The co-existence and inter-penetration of various capitalist and non-capitalist relations in Peruvian society gives a 'flexibility' to social and economic processes: it is this flexibility that is studied in depth through the analysis of small-scale commercial activities. The argument is developed using detailed field data concerning the village of Pucara in the Mantaro region, concentrating on the importance of cash income for the functioning of the household economy, the role of non-agricultural occupations, and the part played by kinship and interpersonal networks in the process of social reproduction of the household unit
Assessing molecular outflows and turbulence in the protostellar cluster Serpens South
Molecular outflows driven by protostellar cluster members likely impact their
surroundings and contribute to turbulence, affecting subsequent star formation.
The very young Serpens South cluster consists of a particularly high density
and fraction of protostars, yielding a relevant case study for protostellar
outflows and their impact on the cluster environment. We combined CO
observations of this region using the Combined Array for Research in
Millimeter-wave Astronomy (CARMA) and the Institut de Radioastronomie
Millim\'{e}trique (IRAM) 30 m single dish telescope. The combined map allows us
to probe CO outflows within the central, most active region at size scales of
0.01 pc to 0.8 pc. We account for effects of line opacity and excitation
temperature variations by incorporating CO and CO data for the
and transitions (using Atacama Pathfinder Experiment and
Caltech Submillimeter Observatory observations for the higher CO transitions),
and we calculate mass, momentum, and energy of the molecular outflows in this
region. The outflow mass loss rate, force, and luminosity, compared with
diagnostics of turbulence and gravity, suggest that outflows drive a sufficient
amount of energy to sustain turbulence, but not enough energy to substantially
counter the gravitational potential energy and disrupt the clump. Further, we
compare Serpens South with the slightly more evolved cluster NGC 1333, and we
propose an empirical scenario for outflow-cluster interaction at different
evolutionary stages.Comment: 26 pages, 15 figures, accepted for publication in the Astrophysical
Journa
El Compromiso de enseñar química con criterios de sostenibilidad: la química verde
Los beneficios que aporta la química a la sociedad son muchos, sin embargo no goza de gran aceptación
popular. La enseñanza de la química orientada a criterios de sostenibilidad podría mejorar su
aceptación social y su interés. La química verde ha ido avanzando en las áreas de investigación y
desarrollo. Su punto clave es que sin usar ni producir sustancias peligrosas, el riesgo es nulo y no es
necesario el tratamiento de residuos. La mayoría de los procesos de síntesis desarrollados con criterios
de sostenibilidad son demasiado complejos para la enseñanza no universitaria. Sin embargo,
puede ser viable la introducción de conceptos asequibles a través la presentación de casos.Els beneficis que aporta la química a la societat són nombrosos, tot i així no té gaire acceptació
popular. Lensenyament de la química orientada a criteris de sostenibilitat podria millorar la seva
acceptació social i el seu interès. La química verda ha anat avançant en les àrees de recerca i desenvolupament.
El seu punt clau és que sense utilitzar ni produir substàncies perilloses el risc és nul i
no es necessari el tractament de residus. La major part dels processos de síntesi desenvolupats amb
criteris de sostenibilitat són massa complexes per a lensenyament no universitari. Tanmateix, pot
ser viable la introducció de conceptes assequibles mitjançant la presentació de casos
Action research on electrochemistry learning. Conceptual modelling intervention to promote disciplinary understanding, scientific inquiry, and reasoning
Students in engineering-science programmes often struggle with theoretical concepts, while they tend to adopt a surface approach to learning. We suggest that this can be tackled by promoting a specific higher-order thinking skill (HOTS) that enables drawing connections between physical phenomena and theoretical concepts representing them. We designed an intervention to support students in achieving deep insight into electrochemical phenomena, while developing this HOTS. Such intervention aims to scaffold students' learning and development by introducing conceptual modelling as an essential thinking skill of engineering-scientists, and as a strategy to build scientific understanding of natural phenomena. Therefore, conceptual modelling constitutes a main learning objective of this novel course. This paper reports an empirical investigation into how students deal with concepts and complexity, and to what extent the intervention has any measurable effects on the learning outcomes. This phenomenological investigation integrates considerations from various disciplines, and relies on multiple data sources, i.e., students' documents (lab journals and reports), observations of students in action (in discussions with their tutors and while performing lab experiments), and video stimulated-recall interviews. The results show little effect of the intervention, as implemented, suggesting how challenging it is for students (and instructors) to shift from traditional learning-and-teaching approaches, towards an epistemology of knowledge construction for specific problems. The findings are informative for revision of the intervention and generate specific recommendations. Concurrently, our operationalisation of the conceptual framework proves powerful in detecting qualitative differences in HOTS. Plausible implications for research and educational practice in science-engineering education are discussed.</p
The UN in the lab
We consider two alternatives to inaction for governments combating terrorism, which we term Defense and Prevention. Defense consists of investing in resources that reduce the impact of an attack, and generates a negative externality to other governments, making their countries a more attractive objective for terrorists. In contrast, Prevention, which consists of investing in resources that reduce the ability of the terrorist organization to mount an attack, creates a positive externality by reducing the overall threat of terrorism for all. This interaction is captured using a simple 3×3 “Nested Prisoner’s Dilemma” game, with a single Nash equilibrium where both countries choose Defense. Due to the structure of this interaction, countries can benefit from coordination of policy choices, and international institutions (such as the UN) can be utilized to facilitate coordination by implementing agreements to share the burden of Prevention. We introduce an institution that implements a burden-sharing policy for Prevention, and investigate experimentally whether subjects coordinate on a cooperative strategy more frequently under different levels of cost sharing. In all treatments, burden sharing leaves the Prisoner’s Dilemma structure and Nash equilibrium of the game unchanged. We compare three levels of burden sharing to a baseline in a between-subjects design, and find that burden sharing generates a non-linear effect on the choice of the efficient Prevention strategy and overall performance. Only an institution supporting a high level of mandatory burden sharing generates a significant improvement in the use of the Prevention strategy
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