398 research outputs found

    A Look at Women and Abortion in the United States

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    The issue of abortion is defined by ethical questions and, often, controversial views. This paper argues the importance of a coherent and enhanced effort to study the quantitative relationship between women’s characteristics and the average number of abortions in the United States. It specifically looks at the average number of previous abortions and socioeconomic and demographic characteristics, as this relationship has not been explored before in the existing literature. We expect to establish a correlation between the average number of previous abortions and characteristics such as age, marital status, income and highest degree of education completed. An empirical model is developed, and then studied using regression analysis. Even though this study has limitations stemming from the nature of the data and the methodology employed, it illustrates that variables such as age, marital status, religion and education, employment status, income, and metropolitan status do influence the number of previous abortions a woman has had. The broader implications of this study suggest that the issue of abortion should be addressed with a clear focus on the most interested party, namely, women

    Anticipation in the cognitive structure of speechreading in deaf pupils

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    Anticipation is one of the basic components in the cognitive structure of speechreading. In order to study the probability prediction ability, determining the skills for correct decoding and interpretation of visually perceived oral information by deaf people; an experiment has been carried out involving 91 pupils aged between 7 and 12, integrated into general education schools. Participants in the study have a hearing loss of ≥90 dB. The results obtained demonstrate a high degree of correlation between linguistic and meaningful prediction ability and children’s speechreading skills. There is also a directly proportional relationship between the chronological age of the students and the level of development of their anticipation ability

    Recovering star formation histories: Integrated-light analyses vs stellar colour-magnitude diagrams

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    Accurate star formation histories (SFHs) of galaxies are fundamental for understanding the build-up of their stellar content. However, the most accurate SFHs - those obtained from colour-magnitude diagrams (CMDs) of resolved stars reaching the oldest main sequence turnoffs (oMSTO) - are presently limited to a few systems in the Local Group. It is therefore crucial to determine the reliability and range of applicability of SFHs derived from integrated light spectroscopy, as this affects our understanding of unresolved galaxies from low to high redshift. To evaluate the reliability of current full spectral fitting techniques in deriving SFHs from integrated light spectroscopy by comparing SFHs from integrated spectra to those obtained from deep CMDs of resolved stars. We have obtained a high signal--to--noise (S/N \sim 36.3 per \AA) integrated spectrum of a field in the bar of the Large Magellanic Cloud (LMC) using EFOSC2 at the 3.6 meter telescope at La Silla Observatory. For this same field, resolved stellar data reaching the oMSTO are available. We have compared the star formation rate (SFR) as a function of time and the age-metallicity relation (AMR) obtained from the integrated spectrum using {\tt STECKMAP}, and the CMD using the IAC-star/MinnIAC/IAC-pop set of routines. For the sake of completeness we also use and discuss other synthesis codes ({\tt STARLIGHT} and {\tt ULySS}) to derive the SFR and AMR from the integrated LMC spectrum. We find very good agreement (average differences \sim 4.1 %\%) between the SFR(t) and the AMR obtained using {\tt STECKMAP} on the integrated light spectrum, and the CMD analysis. {\tt STECKMAP} minimizes the impact of the age-metallicity degeneracy and has the advantage of preferring smooth solutions to recover complex SFHs by means of a penalized χ2\chi^2. [abridged]Comment: 23 pages, 24 figures. Accepted for publication in A&A (6 Sep 2015

    Functional and structural leaf plasticity determine photosynthetic performances during drought stress and recovery in two platanus orientalis populations from contrasting habitats.

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    In the context of climatic change, more severe and long-lasting droughts will modify the fitness of plants, with potentially worse consequences on the relict trees. We have investigated the leaf phenotypic (anatomical, physiological and biochemical) plasticity in well-watered, drought- stressed and re-watered plants of two populations of Platanus orientalis, an endangered species in the west of the Mediterranean area. The two populations originated in contrasting climate (drier and warmer, Italy (IT) population; more humid and colder, Bulgaria (BG) population). The IT control plants had thicker leaves, enabling them to maintain higher leaf water content in the dry environment, and more spongy parenchyma, which could improve water conductivity of these plants and may result in easier CO2 diffusion than in BG plants. Control BG plants were also characterized by higher photorespiration and leaf antioxidants compared to IT plants. BG plants responded to drought with greater leaf thickness shrinkage. Drought also caused substantial reduction in photosynthetic parameters of both IT and BG plants. After re-watering, photosynthesis did not fully recover in either of the two populations. However, IT leaves became thicker, while photorespiration in BG plants further increased, perhaps indicating sustained activation of defensive mechanisms. Overall, our hypothesis, that plants with a fragmented habitat (i.e., the IT population) lose phenotypic plasticity but acquire traits allowing better resistance to the climate where they became adapted, remains confirmed

    A new method for reconstructing the density distribution of matter in the disks of spiral galaxies from the rotation velocity curve in it

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    In this paper we propose a new method for reconstructing the surface density of matter in flat disks of spiral galaxies. The surface density is expressed through observational rotation velocity curves of visible matter in the disks of spiral galaxies. The new method is not based on quadrature of special functions. The found solution is used for processing and analysis of observational data from several spiral galaxies. The new method can be used to more accurately estimate the amount of dark matter in spiral galaxies.Comment: 18 pages, 6 figure

    Nonlinear Parabolic Equations arising in Mathematical Finance

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    This survey paper is focused on qualitative and numerical analyses of fully nonlinear partial differential equations of parabolic type arising in financial mathematics. The main purpose is to review various non-linear extensions of the classical Black-Scholes theory for pricing financial instruments, as well as models of stochastic dynamic portfolio optimization leading to the Hamilton-Jacobi-Bellman (HJB) equation. After suitable transformations, both problems can be represented by solutions to nonlinear parabolic equations. Qualitative analysis will be focused on issues concerning the existence and uniqueness of solutions. In the numerical part we discuss a stable finite-volume and finite difference schemes for solving fully nonlinear parabolic equations.Comment: arXiv admin note: substantial text overlap with arXiv:1603.0387
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