936 resultados para Thought in a hostile world: the evolution of human cognition
Resumo:
Successful implantation is still the limiting step in IVF. We hypothesized that maternal plasma concentrations of certain cytokines at the time of embryo transfer could predict the likelihood of successful implantation and pregnancy. sIL-2R, IL-6, LIF, and MMP2 concentrations were measured in plasma from 160 IVF patients (natural and stimulated IVF cycles) on the morning of the embryo transfer (ET0) and 14days later (ET+14). Patients were ultimately subdivided into four groups depending on the IVF treatment outcome (pregnancy failure, biochemical pregnancy, first-trimester miscarriage and normal term delivery). In natural and stimulated IVF cycles at ET0, sIL-2R concentrations were threefold higher in biochemical pregnancies than in pregnancy failures (P=0.020), and in natural cycles only, 2.5-fold higher in normal term deliveries than in pregnancy failures (P=0.023). Conversely, in natural and stimulated IVF cycles at ET0, LIF concentrations were one third lower in biochemical pregnancies/first-trimester miscarriages compared with pregnancy failures (P=0.042). We suggest that high sIL-2R and low LIF concentrations in maternal plasma on the morning of the embryo transfer might be associated with increased risks of early pregnancy loss, while a basal level of sIL-2R is necessary for normal term delivery outcome. Both cytokine measurements might therefore be useful in the management of IVF patients, and modulation of their concentrations could be investigated as a therapeutic alternative for women with abnormal concentrations at the time of embryo transfer.
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Professional services require certain organizational patterns in order to avoid information asymmetries and external effects. These same patterns are used within production structures involving various degrees of monopoly. However, competitive restraints are justified today only when substantial external effects are clearly present, whereas information asymmetries hardly justify such restraints because reputational investments have become widespread in the economy and are relatively efficient in overcoming such asymmetries. As a consequence, innovation in the production of externalities can make competitive constraints unnecessary.
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In this paper a p--median--like model is formulated to address theissue of locating new facilities when there is uncertainty. Severalpossible future scenarios with respect to demand and/or the travel times/distanceparameters are presented. The planner will want a strategy of positioning thatwill do as ``well as possible'' over the future scenarios. This paper presents a discrete location model formulation to address this P--Medianproblem under uncertainty. The model is applied to the location of firestations in Barcelona.
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This study aimed to evaluate the influence of water velocity speed on the local distribution and taxocenosis structure of blackfly larvae. The larvae were collected from two adjacent streams located in the municipality of Angra dos Reis (RJ): Caputera River and one of its tributaries. Riffle litter patches were sampled randomly using a 30 x 30 cm quadrat. Four blackfly species were found: Simulium incrustatum s. l. Lutz, 1910; Simulium (Inaequalium) sp. ; Simulium pertinax s. l. Kollar, 1832 and Simulium subpallidum s. l. Lutz, 1909. Among these species, Simulium pertinax s. l. was clearly associated with higher water current speeds, while Simulium subpallidum s. l. showed association with lower water velocities, and Simulium (Inaequalium) sp. had a relatively constant distribution along the water current gradient.
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Humans differ substantially with respect to susceptibility to human immunodeficiency virus type 1 (HIV-1). We evaluated variants of nine host genes participating in the viral life cycle for their role in modulating HIV-1 infection. Alleles were assessed ex vivo for their impact on viral replication in purified CD4 T cells from healthy blood donors (n = 128). Thereafter, candidate alleles were assessed in vivo in a cohort of HIV-1-infected individuals (n = 851) not receiving potent antiretroviral therapy. As a benchmark test, we tested 12 previously reported host genetic variants influencing HIV-1 infection as well as single nucleotide polymorphisms in the nine candidate genes. This led to the proposition of three alleles of PML, TSG101, and PPIA as potentially associated with differences in progression of HIV-1 disease. In a model considering the combined effects of new and previously reported gene variants, we estimated that their effect might be responsible for lengthening or shortening by up to 2.8 years the period from 500 CD4 T cells/mul to <200 CD4 T cells/mul.
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Revision of the Neotropical species of Empididae (Diptera) described by Mario Bezzi. IX. The species described in Atrichopleura Bezzi and the description of a new species. Four Neotropical species of Empididae described by Bezzi in Atrichopleura Bezzi, 1909 are redescribed: A. crassa (lectotype, pres. desig.), A. hirtipes (lectotype, pres. desig.), A. nitida (lectotype, pres. desig.), A. schnusei (lectotype, pres. desig.). Atrichopleura bezzii sp. nov. is described from among syntypes of A. schnusei.
Resumo:
The number of non-profit organizations has grown considerably over thelast decades, however management control techniques are not being introducedwith the same frequency as in lucrative organizations. The increasedcompetition in this sector has created a growing interest in managementcontrol techniques but with little empirical research in the area. Withthe aim to throw some light over the uses of management control inprofessional associations we have focused in the associations foreconomists in Spain as a particular case of a non-lucrative body.Specifically, the paper comprises three surveys addressed to the followingsectors:1) To the 30 Spanish associations of economists.2) To associations related to the business and/or economics area operatingin the United Kingdom.3) To members of the association of economists in Catalonia (Col.legid'Economistes de Catalunya).Results indicate that management accounting tools are used exceptionally,many times only the minimum legal requirements. The critical situation ofthe associations of economists in Spain requires the implementation ofinformation systems, specially taking into account the differentspecialities of economists and offering to its members, services and productsthat are not available through profit organizations.
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Foreign language skills represent a form of human capital that can be rewarded in the labor market. Drawing on data from the Adult Education Survey of 2007, this is the first study estimating returns to foreign language skills in Turkey. We contribute to the literature on the economic value of language knowledge, with a special focus on a country characterized by fast economic and social development. Although English is the most widely spoken foreign language in Turkey, we initially consider the economic value of different foreign languages among the employed males aged 25 to 65. We find positive and significant returns to proficiency in English and Russian, which increase with the level of competence. Knowledge of French and German also appears to be positively rewarded in the Turkish labor market, although their economic value seems mostly linked to an increased likelihood to hold specific occupations rather than increased earnings within occupations. Focusing on English, we also explore the heterogeneity in returns to different levels of proficiency by frequency of English use at work, birth-cohort, education, occupation and rural/urban location. The results are also robust to the endogenous specification of English language skills.
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A widely dispersed network of hypothalamic GnRH neurons controls the reproductive axis in mammals. Genetic investigation of the human disease model of isolated GnRH deficiency has revealed several key genes crucial for GnRH neuronal ontogeny and GnRH secretion. Among these genes, prokineticin 2 (PROK2), and PROK2 receptor (PROKR2) have recently emerged as critical regulators of reproduction in both mice and humans. Both prok2- and prokr2-deficient mice recapitulate the human Kallmann syndrome phenotype. Additionally, PROK2 and PROKR2 mutations are seen in humans with Kallmann syndrome, thus implicating this pathway in GnRH neuronal migration. However, PROK2/PROKR2 mutations are also seen in normosmic GnRH deficiency, suggesting a role for the prokineticin signaling system in GnRH biology that is beyond neuronal migration. This observation is particularly surprising because mature GnRH neurons do not express PROKR2. Moreover, mutations in both PROK2 and PROKR2 are predominantly detected in the heterozygous state with incomplete penetrance or variable expressivity frequently seen within and across pedigrees. In some of these pedigrees, a "second hit" or oligogenicity has been documented. Besides reproduction, a pleiotropic physiological role for PROK2 is now recognized, including regulation of pain perception, circadian rhythms, hematopoiesis, and immune response. Therefore, further detailed clinical studies of patients with PROK2/PROKR2 mutations will help to map the broader biological role of the PROK2/PROKR2 pathway and identify other interacting genes/proteins that mediate its molecular effects in humans.
Resumo:
Among the types of remote sensing acquisitions, optical images are certainly one of the most widely relied upon data sources for Earth observation. They provide detailed measurements of the electromagnetic radiation reflected or emitted by each pixel in the scene. Through a process termed supervised land-cover classification, this allows to automatically yet accurately distinguish objects at the surface of our planet. In this respect, when producing a land-cover map of the surveyed area, the availability of training examples representative of each thematic class is crucial for the success of the classification procedure. However, in real applications, due to several constraints on the sample collection process, labeled pixels are usually scarce. When analyzing an image for which those key samples are unavailable, a viable solution consists in resorting to the ground truth data of other previously acquired images. This option is attractive but several factors such as atmospheric, ground and acquisition conditions can cause radiometric differences between the images, hindering therefore the transfer of knowledge from one image to another. The goal of this Thesis is to supply remote sensing image analysts with suitable processing techniques to ensure a robust portability of the classification models across different images. The ultimate purpose is to map the land-cover classes over large spatial and temporal extents with minimal ground information. To overcome, or simply quantify, the observed shifts in the statistical distribution of the spectra of the materials, we study four approaches issued from the field of machine learning. First, we propose a strategy to intelligently sample the image of interest to collect the labels only in correspondence of the most useful pixels. This iterative routine is based on a constant evaluation of the pertinence to the new image of the initial training data actually belonging to a different image. Second, an approach to reduce the radiometric differences among the images by projecting the respective pixels in a common new data space is presented. We analyze a kernel-based feature extraction framework suited for such problems, showing that, after this relative normalization, the cross-image generalization abilities of a classifier are highly increased. Third, we test a new data-driven measure of distance between probability distributions to assess the distortions caused by differences in the acquisition geometry affecting series of multi-angle images. Also, we gauge the portability of classification models through the sequences. In both exercises, the efficacy of classic physically- and statistically-based normalization methods is discussed. Finally, we explore a new family of approaches based on sparse representations of the samples to reciprocally convert the data space of two images. The projection function bridging the images allows a synthesis of new pixels with more similar characteristics ultimately facilitating the land-cover mapping across images.