5,280 research outputs found

    Gender differences and the timing of first marriages

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    In this article we provide a simple model of the marriage market where singles search for spouses. In our model economy men and women live for many years and they differ in their survival probabilities, in their fecundity, and in their earnings. We show that modelling the marriage decision in a very simple model economy is sufficient to account for much of the observed marriage behavior in the United States in the year 2000. We conclude that gender differences in fecundity are all important in accounting for marriage behavior, and that differences in earnings matter little. We also conclude that, even though they are in short supply, the market power of fecund women is not enough for them to demand compensation in all cases. And that studying the marriage decision without modelling explicitly the roles played by age and by fecundity, as has been typically done by the previous literature, makes little sense.Marriage, Search, Sex ratio

    Epidermal growth factor coordinately regulates the expression of prostaglandin G/H synthase and cytosolic phospholipase A2 genes in embryonic mouse cells.

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    Confluent, primary cultures of mouse embryo palate mesenchyme (MEPM) cells are refractory to activation of phospholipase A2 (PLA2) by the calcium ionophore A23187. However, treatment of these cultures with epidermal growth factor (EGF) permits the cells to activate PLA2 in response to A23187. We have developed this finding by exploring molecular mechanisms by which growth factors modulate mobilization and metabolism of arachidonic acid. We found chronic treatment (\u3e 6 h) of confluent MEPM cells with EGF (a) increases their ability to metabolize exogenous arachidonic acid to prostaglandin E2 (PGE2) and (b) stimulated constitutive expression of activities of PLA2 and cyclooxygenase (CyOx). Immunoprecipitation of [35S]proteins and Western blot analysis revealed EGF treatment stimulated synthesis and accumulation of PLA2c, CyOx-1, and CyOx-2. Northern hybridization analysis revealed EGF increased the steady-state levels of a transcript for the high molecular weight, cytosolic PLA2 (PLA2c), and both the 2.8- and 4.2-kb transcripts for CyOx-1 and CyOx-2, respectively. In vitro nuclear transcription assays showed a parallel increase in the transcription rate of the genes corresponding to CyOx-1 and PLA2c, but not CyOx-2, in response to EGF. Treatment with EGF had no effect on either synthesis of the low molecular weight, group II PLA2, accumulation of its transcript, or the transcription rate of its gene. Coordinate regulation of activities of PLA2 and CyOx in response to EGF did not parallel the mitogenic effects of EGF on confluent MEPM cells

    Regulation of transforming growth factor-beta 1 gene expression by glucocorticoids in normal human T lymphocytes.

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    Glucocorticoids (GC) modulate immune function in a number of ways, including suppression of T cell proliferation and other IL-2-mediated T cell functions. These inhibitory effects are similar to those induced by transforming growth factor-beta 1 (TGF-beta 1), a cytokine with potent T cell inhibiting activities. We examined the hypothesis that GC effects may be at least partially achieved through modulation of the expression of the TGF-beta 1 gene in activated T cells. Normal T cells were cultured with or without purified phytohemagglutinin (PHA-p) and 4 beta-phorbol 12-myristate 13-acetate (PMA) in the presence or absence of the synthetic GC, dexamethasone (100-200 micrograms/ml). The production of latent and active forms of TGF beta by these cells were analyzed by immunoblotting and bioassays. The steady-state levels of TGF-beta 1 mRNA were analyzed in total RNA from these cells by Northern hybridizations using a human TGF-beta 1 cDNA. The results showed that dexamethasone caused an increase in TGF beta production and a dose-dependent two to fourfold increase in TGF-beta 1 mRNA in activated as well as in unstimulated T cells, 1 h after exposure of the cultures to the steroid. The increase in TGF-beta 1 mRNA levels by dexamethasone was further potentiated two to threefold by cycloheximide, suggesting that the steroid effect may be due to inhibition of the synthesis of proteins that decrease TGF-beta 1 gene transcription or the stability of its transcripts. Finally, in vitro nuclear transcription studies indicated the dexamethasone effects on TGF-beta 1 gene expression to be largely transcriptional

    A Tool for Integer Homology Computation: Lambda-At Model

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    In this paper, we formalize the notion of lambda-AT-model (where λ\lambda is a non-null integer) for a given chain complex, which allows the computation of homological information in the integer domain avoiding using the Smith Normal Form of the boundary matrices. We present an algorithm for computing such a model, obtaining Betti numbers, the prime numbers p involved in the invariant factors of the torsion subgroup of homology, the amount of invariant factors that are a power of p and a set of representative cycles of generators of homology mod p, for each p. Moreover, we establish the minimum valid lambda for such a construction, what cuts down the computational costs related to the torsion subgroup. The tools described here are useful to determine topological information of nD structured objects such as simplicial, cubical or simploidal complexes and are applicable to extract such an information from digital pictures.Comment: Journal Image and Vision Computing, Volume 27 Issue 7, June, 200

    A Knowledge-Based Entrepreneurial Approach for Business Intelligence in Strategic Technologies: Bio-Mems

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    We propose a knowledge-based entrepreneurial (KBE) approach for business intelligence in strategic technologies at industrial sectors. The KBE approach is at the convergence of business intelligence and knowledge management and is used for advising users in business decisions and potential risks. Our approach comprises both a technology roadmap model as well as a knowledge-based entrepreneurial portal for various technologies. We use the Biological-Micro-Electrical-and- Mechanical-Systems industry (Bio-MEMS) to illustrate the approach. The technology roadmap model identifies the main actors, defines their roles and specifies the issues to be addressed. It handles information about main products, market trends, companies, research centers, application domains, products, standardization, and intellectual properties issues. The portal provides knowledge about the main actors through automation facilities based on digital libraries, searching and knowledge extraction from databases, data-ware houses and the Web. We explain how the KBE is helping Bio-MEMS users in business analysis

    Determination of heat wave definition temperatures in Spain at an isoclimatic level: time trend of heat wave duration and intensity across the decade 2009–2018

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    Background: In line with WHO guidelines for the implementation of public health prevention plans targeted at the impacts of high temperatures, a heat wave defnition temperature (Tthreshold) was calculated for 182 so called “isoclimatic zones” (IZ) in Spain. As the dependent variable for determining this Tthreshold, we analysed daily all-cause mortality data (ICD-10: A00-R99) for each IZ across the period 2009–2018. The independent variable used was the mean value of the maximum daily temperature of the summer months recorded at meteorological observatories in each IZ. We used Box–Jenkins models to ascertain mortality anomalies, and scatterplots to link these anomalies to the temperatures at which they occurred, thereby determining the Tthreshold for each IZ. We then calculated how many heat waves had occurred in each IZ, as well as their intensity, and analysed their time trend over this period. Results: The results showed that in 52.5% of the IZ, the percentile of the maximum temperatures series of the summer months to which Tthreshold corresponded was below the 95th percentile of the meteorological heat wave defnition in Spain: indeed, it only coincided in 30.7% of cases. The geographical distribution of these percentiles displayed great heterogeneity as a consequence of the local factors that infuence the temperature–mortality relationship. The trend in the number of heat waves analysed indicated an overall increase in Spain at a rate of 3.9 heat waves per decade, and a similar rise in mean annual intensity of 9.5 °C/decade. These time-trend values were higher than those yielded by analysing the trend in meteorological heat waves based on the 95th percentile. Conclusions: The results obtained in this study indicate the need to use a heat wave defnition based on epidemiological temperature–mortality studies, rather than on values based on meteorological percentiles. This could be minimising estimated health impacts in analyses of future impacts attributable to heat.Acknowledgements and funding The authors would like to express their gratitude for the following grants from the Carlos III Institute of Health (Instituto de Salud Carlos III/ISCIII) for the ENPY 304/20, and ENPY 436/21 projects.S

    Comparative study of CuO supported on CeO2, Ce0.8Zr0.2O2 and Ce0.8Al0.2O2 based catalysts in the CO-PROX reaction

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    CuO supported on CeO2, Ce0.8Zr0.2O2 and Ce0.8Al0.2O2 based catalysts (6%wt Cu) were synthesized and tested in the preferential oxidation of CO in a H2-rich stream (CO-PROX). Nanocrystalline supports, CeO2 and solid solutions of modified CeO2 with zirconium and aluminum were prepared by a freeze-drying method. CuO was supported by incipient wetness impregnation and calcination at 400 C. All catalysts exhibit high activity in the CO-PROX reaction and selectivity to CO2 at low reaction temperature, being the catalyst supported on CeO2 the more active and stable. The influence of the presence of CO2 and H2O was also studied

    ADDISC lumbar disc prosthesis : Analytical and FEA testing of novel implants

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    The intact intervertebral disc is a six-freedom degree elastic deformation structure with shock absorption. 'Ball-and-socket' TDR do not reproduce these properties inducing zygapophyseal joint overload. Elastomeric TDRs reproduce better normal disc kinematics, but repeated core deformation causes its degeneration. We aimed to create a new TDR (ADDISC) reproducing healthy disc features. We designed TDR, analyzed (Finite Element Analysis), and measured every 500,000 cycles for 10 million cycles of the flexion-extension, lateral bending, and axial rotation cyclic compression bench-testing. In the inlay case, we weighted it and measured its deformation. ADDISC has two semi-spherical articular surfaces, one rotation centre for flexion, another for extension, the third for lateral bending, and a polycarbonate urethane inlay providing shock absorption. The first contact is between PCU and metal surfaces. There is no metal-metal contact up to 2000 N, and CoCr28Mo6 absorbs the load. After 10 million cycles at 1.2-2.0 kN loads, wear 140.96 mg (35.50 mm3), but no implant failures. Our TDR has a physiological motion range due to its articular surfaces' shape and the PCU inlay bumpers, minimizing the facet joint overload. ADDISC mimics healthy disc biomechanics and Instantaneous Rotation Center, absorbs shock, reduces wear, and has excellent long-term endurance

    Serum melatonin levels during the first seven days of severe sepsis diagnosis are associated with sepsis severity and mortality

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    Objective: Higher serum melatonin levels have previously been found in patients with severe sepsis who died within 30 days of diagnosis than in survivors. The objective of our study were to determine whether serum melatonin levels during the first seven days of severe sepsis diagnosis could be associated with sepsis severity and mortality. Methods: Multicentre study in eight Spanish Intensive Care Units which enrolled 308 patients with severe sepsis. We determined serum levels of melatonin, malondialdehyde (as biomarker of lipid peroxidation) and tumor necrosis factor-alpha at days 1, 4 and 8 of severe sepsis diagnosis. The study's primary endpoint was 30-day mortality. Results: A total of 103 patients had died and 205 survived at 30 days of severe sepsis diagnosis, with the non-survivors presenting higher serum melatonin levels at days 1 (p<0.001), 4 (p<0.001) and 8 (p<0.001) of severe sepsis diagnosis than the survivor patient group. The multiple logistic regression analysis found that serum melatonin levels at days 1, 4 and 8 of severe sepsis diagnosis (p<0.001, p = 0.01 and p = 0.001, respectively) were associated with mortality adjusted for age, serum lactic acid, SOFA score and diabetes mellitus. Conclusions: The novel and more interesting findings of our study were that serum melatonin levels during the first seven days of severe sepsis diagnosis are associated with sepsis severity and mortality. (C) 2017 Elsevier Espana, S.L.U. and Sociedad Espanola de Enfermedades lnfecciosas y Microbiologia Clinica
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