676,612 research outputs found

    Exogenous gonadotropins have little impact on follicular but considerable effect on serum cytokine concentrations – a comparison between Natural Cycle and stimulated IVF using a multiplexed assay platform

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    Introduction: Throughout follicular growth and subsequent corpus luteum formation the leukocyte number increases and follicular vascularisation changes. These processes are enhanced under exogenous stimulation with gonadotropins. Cytokines released by leukocytes contribute to further recruitment and vascularisation of the follicle, and they play an important role in regulating ovarian steroidogenesis by influencing theca and granulosa–lutein cell function. Changes in cytokine and vascular endothelial growth factor (VEGF) concentrations in the ovary as a consequence of gonadotropin stimulation may negatively influence oocyte quality. In this project we have compared the intrafollicular production of inflammatory cytokines and growth factors between natural IVF cycles (NC) and classical, gonadotropin-stimulated IVF cycles (gsIVF). Material and Methods: Serum on the day of oocyte retrieval and follicular fluid (FF) were collected in 37 NC and 39 gsIVF cycles. Thirteen women within this population underwent one NC and one gsIVF cycle each. A total of 14 cytokines from Bio-Plex panels I and II were determined in matched serum and FF samples using Luminex xMAP technology on the Bio-Plex(R) platform, using the serum protocol. Results: Tumour necrosis factor-alpha, RANTES, eotaxin and interferon-gamma-induced protein-10 levels were lower in FF than in serum, and thus not further investigated. Interleukin (IL)-6, -8, -10, -15, -18, monocyte chemotactic protein-1 (MCP-1), VEGF and leukaemia inhibitory factor (LIF) showed higher median concentrations in FF than in serum, indicating possible ovarian production. Moreover, most of these showed higher evels in the gsIVF than in the NC groups in the serum, but not in the follicular fluid. IL-8 was reduced in gsIVF cycles. Conclusion: The fact that serum but not FF levels of the studied cytokines were higher in the stimulated than in the natural cycles can be attributed to the increased number of active follicles present after controlled ovarian stimulation

    Exogenous underdevelopment pattern

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    The main dynamics of capitalism is the creation of overproduction in order to search for an internal and foreign market outlet. While increasing the overproduction, both the expansion process and the internationalization of consumption raise. The context just described leads to think about the existence of rich and emerging economies producing an excess of supply compared with their internal demand (net supply) that must be allocated to the poor economies showing an excess of demand compared with their internal supply (net demand). We are, after all, in the compensating structure of the world economy, where the poor countries are setting against the rich and emerging countries; these last two are in competition with each other. Besides, the poor countries absorb the surplus of the rich and emerging ones. The assertion of monetarism, in the last decades, encouraging the market outlets abroad to the detriment of the outlets towards the public sector, leads to stress the tensions between the advantaged and disadvantaged nations. This context makes more doubtful the future economical perspectives. The compensating structure of the world economy facilitates the exogenous nature of the underdevelopment of wide areas of the planet that are addressed to absorb the productive excesses of the advanced economies. The purpose of this current theoretical contribution is just to formalize, through an appropriate economical and mathematical pattern, the interdependence between the strong economical world and the weak economical world.Monetarism; Underdevelopment; Market outlet; Overproduction.

    Measuring the Drivers of Metropolitan Growth: The Export Price Index

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    The Export Price Index (EPI) is a measure of exogenous price shocks to a city’s export industries. Thus far the EPI has been used to estimate models of metropolitan statistical area employment demand and appears to capture exogenous demand shocks to the regional economy. This article explains the intuition behind and construction of the EPI. Glaeser (2008) has noted that because “the economic theory of cities emphasizes a search for exogenous causes of endogenous outcomes like local wages, housing prices, and city growth, it is unsurprising that the economic empirics on cities have increasingly focused on the quest for exogenous sources of variation.” The EPI is such an exogenous cause. The EPI data discussed in this note are available through The George Washington University Center for Economic Research website at http://www.gwu.edu/~cer1/datasets/datasets.html

    Direct introduction of cloned DNA into the sea urchin zygote nucleus, and fate of injected DNA

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    A method is described for microinjection of cloned DNA into the zygote nucleus of Lytechinus variegatus. Eggs of this species are unusually transparent, facilitating visual monitoring of the injection process. The initial fate of injected DNA fragments appears similar to that observed earlier for exogenous DNA injected into unfertilized egg cytoplasm. Thus after end-to-end ligation, it is replicated after a lag of several hours to an extent indicating that it probably participates in most of the later rounds of DNA synthesis undergone by the host cell genomes during cleavage. The different consequences of nuclear versus cytoplasmic injection are evident at advanced larval stages. Larvae descendant from eggs in which exogenous DNA was injected into the nuclei are four times more likely (32% versus 8%) to retain this DNA in cell lineages that replicate very extensively during larval growth, i.e. the lineages contributing to the imaginal rudiment, and thus to display greatly enhanced contents of the exogenous DNA. Similarly, 36% of postmetamorphic juveniles from a nuclear injection sample retained the exogenous DNA sequences, compared to 12% of juveniles from a cytoplasmic injection sample. However, the number of copies of the exogenous DNA sequences retained per average genome in postmetamorphic juveniles was usually less than 0.1 (range 0.05-50), and genome blot hybridizations indicate that these sequences are organized as integrated, randomly oriented, end-to-end molecular concatenates. It follows that only a small fraction of the cells of the average juvenile usually retains the exogenous sequences. Thus, even when introduced by nuclear microinjection, the stable incorporation of exogenous DNA in the embryo occurs in a mosaic fashion, although in many recipients the DNA enters a wider range of cell lineages than is typical after cytoplasmic injection. Nuclear injection would probably be the route of choice for studies of exogenous DNA function in the postembryonic larval rudiment

    Validating plans with exogenous events

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    We are concerned with the problem of deciding the validity of a complex plan involving interacting continuous activity. In these situations there is a need to model and reason about the continuous processes and events that arise as a consequence of the behaviour of the physical world in which the plan is expected to execute. In this paper we describe how events, which occur as the outcome of uncontrolled physical processes, can be taken into account in determining whether a plan is valid with respect to the domain model. We do not consider plan generation issues in this paper but focus instead on issues in domain modelling and plan validation

    Exogenous impact and conditional quantile functions

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    An exogenous impact function is defined as the derivative of a structural function with respect to an endogenous variable, other variables, including unobservable variables held fixed. Unobservable variables are fixed at specific quantiles of their marginal distributions. Exogenous impact functions reveal the impact of an exogenous shift in a variable perhaps determined endogenously in the data generating process. They provide information about the variation in exogenous impacts across quantiles of the distributions of the unobservable variables that appear in the structural model. This paper considers nonparametric identification of exogenous impact functions under quantile independence conditions. It is shown that, when valid instrumental variables are present, exogenous impact functions can be identified as functionals of conditional quantile functions that involve only observable random variables. This suggests parametric, semiparametric and nonparametric strategies for estimating exogenous impact functions.