1,932 research outputs found
Age differences between distributions of genotypes among pregnant women: evidence of fertility selection.
SummaryThe number of children produced by a modern woman is usually below her total reproductive capacity and is determined by circumstances other than natural selection. It is, therefore, practically impossible to detect differences in natural fertilities associated with different types (e.g. phenotypes, genotypes) of women. This does not mean, however, that natural selection at the reproductive level cannot at all be detected today. If women of a particular type have high natural fertility, this usually means that they reproduce (become pregnant) at a higher rate than women of a type with lower natural fertility. Hence, when there is a limit on the number of children, women of the first type will reach the limit at an earlier age than women of the second type. As a result, types that have a higher natural fertility should be overrepresented among pregnant women of younger ages and, consequently, underrepresented among older ones, as compared to types with a lower natural fertility. Based on this notion, a model of age-related differences between distributions of types among pregnant women is suggested. The model is applied to data on MNSs-blood group and PGM1 (phosphoglucomutase) types in a sample of pregnant women and an evidence of natural selection at the reproduction level associated with these genetic markers is obtained
An Examination of the Current Status of Rating Agencies and Proposals for Limited Oversight of Such Agencies
This Comment analyzes the market for ratings of both financial securities and insurance companies, and finds significant problems with rating agencies, such as lethargy in changing ratings, political influence, unsolicited ratings, and inaccurate ratings. To ensure that the federal securities laws continue to protect investors, this Comment recommends limited oversight of rating agencies. It proposes that Congress enact legislation granting the Securities and Exchange Commission explicit authority to mandate that all nationally recognized statistical rating organizations register with the SEC, and to establish minimum standards for their designation. Finally, the Comment examines First Amendment concerns associated with the regulation of rating agencies, and concludes that proposed legislation set forth in this paper would not violate the First Amendment
Smoking, haptoglobin and fertility in humans
A prospective study on two samples of consecutive puerperae (total n° 667) from two populations has been carried out in order to investigate the possible effect of smoking habit on relationship between fertility and haptoglobin phenotype
Powder bed monitoring via digital image analysis in additive manufacturing
Due to the nature of Selective Laser Melting process, the built parts suffer from high chances of defects formation. Powders quality have a significant impact on the final attributes of SLM-manufactured items. From a processing standpoint, it is
critical to ensure proper powder distribution and compaction in each layer of the powder bed, which is impacted by particle size distribution, packing density, flowability, and sphericity of the powder particles. Layer-by-layer study of the process can provide better understanding of the effect of powder bed on the final part quality. Image-based processing technique could be used to examine the quality of parts fabricated by Selective Laser Melting through layerwise monitoring and to evaluate the results achieved by other techniques. In this paper, a not supervised methodology based on Digital Image Processing through the build-inmachine camera is proposed. Since the limitation of the optical system in terms of resolution, positioning, lighting, field-of-view, many efforts were paid to the calibration and to the data processing. Its capability to individuate possible defects on SLM parts was evaluated by a Computer Tomography results verification
Phosphotyrosine-protein-phosphatases and human reproduction: an association between low molecular weight acid phosphatase (ACP1) and spontaneous abortion.
ACP1 (low molecular weight acid phosphatase) genetic polymorphism has been studied in 173 women with a history of two or more consecutive spontaneous abortions and in 1508 control subjects, including 482 normal pregnant women. The proportion of carriers of ACP1 *C allele (* A/ *C, *B/*C) in women with a history of repeated spontaneous abortion is lower than in normal pregnant women and other control groups, Women with repeated spontaneous abortion show a specific decrease of ACPI S isoform concentration as compared to normal pregnant women, The other component of ACP I activity, the F isoform, does not show a significant difference between the two groups. The data suggest that women with ACP1 genotypes showing a high concentration of S isoform are relatively 'protected' against spontaneous abortion, Preliminary analysis of a sample of 352 normal puerperae along with their newborn babies supports this hypothesis
Coronary Artery Disease: A Study on the Joint Role of Birth Weight, Adenosine Deaminase, and Gender
An inverse relationship between birth weight and coronary artery diseases is well documented but it remains unclear which exposure in early life might underlie such association. Recently it has been reported an association between adenosine deaminase genetic polymorphism and coronary artery diseases. Gender differences in the degree of this association have been also observed. These observations prompted us to study the possible joint effects of BW, ADA, and gender on the susceptibility to coronary artery diseases. 222 subjects admitted to hospital for nonfatal coronary artery diseases, and 762 healthy consecutive newborns were studied. ADA genotypes were determined by DNA analysis. A highly significant complex relationship has emerged among ADA, birth weight, and gender concerning their role on susceptibility to coronary artery diseases in adult life. Odds ratio analysis suggests that low birth weight is more important in females than in males. ADA∗2 allele appears protective in males, while in females such effect is obscured by birth weight
Modeling of association effects in mixtures of carboxylic acids with associating and non-associating components
http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=6&SID=V21Di6PajaHLPoM3@AJ&page=1&doc=1&colname=WOSThe group contribution with association equation of state GCA-EOS has been applied to calculate thermodynamic properties of
pure compounds and mixtures of carboxylic acids with paraffins, alcohols, water and gases, at low and high pressures. Two associating groups, OH and COOH, were defined. Self- and cross-association in
these mixtures were quantified through two parallel COOH/COOH and OH/OH associations. The validity of this approach is supported by an excellent representation of pure compound properties (vapor pressures and compressibility factors) and phase equilibria in mixtures of (associating + inert) and (associating + associating) components at low and high pressures
The extended gca-eos model for mixtures of fatty oils and derivatives
The Group Contribution Equation of State GC-EOS has been satisfactory applied
to the modeling of high-pressure phase equilibria of supercritical gases (CO2, propane, ethane, dimethylether) with pure triglycerides and natural vegetable oils. The GC-EOS model size-related parameter, i.e. the critical hard sphere diameter, of the high molecular weight compounds were determined by fitting infinite dilution activity coefficients of n-alkanes
in these heavy compounds. In this way the GC-EOS model was able to correlate
and predict vapor-liquid (VLE) and liquid-liquid (LLE) equilibria of these mixtures, using a unique set of parameters, in good agreement with experimental data. In this work the application of the model is extended to mixtures containing fatty oil derivatives, such as fatty acids, fatty acids esters, mono - and diglycerides. The associating effects between molecules are described using an upgraded version of the model, the Group Contribution Associating - EOS. Satisfactory correlation and prediction of experimental VLE, LLE and ginfinite data in binary and ternary mixtures of these products with supercritical gases are
obtained
Selective laser melting process of Al–based pyramidal horns for the w-band: fabrication and testing
In the context of exploring the possibility of using Al-powder Selective Laser Meltingto fabricate horn antennas for astronomical applications at millimeter wavelengths,we describe the design, the fabrication, the mechanical characterization, and theelectromagnetic performance of additive manufactured horn antennas for the W-band. Our aim, in particular, is to evaluate the performance impact of two basickinds of surface post-processing (manual grinding and sand-blasting) to deal withthe well-known issue of high surface roughness in 3D printed devices. We performedcomparative tests of co-polar and cross-polar angular response across the whole W-band, assuming a commercially available rectangular horn antenna as a reference.Based on gain and directivity measurements of the manufactured samples, we finddecibel-level detectable deviations from the behavior of the reference horn antenna,and marginal evidence of performance degradation at the top edge of the W-band.We conclude that both kinds of post-processing allow achieving good performancefor the W-band, but the higher reliability and uniformity of the sand-blasting post-process encourage exploring similar techniques for further development of aluminumdevices at these frequencies
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