22,795 research outputs found

    Age-Gapped and Age-Condensed Lineages: Patterns of Intergenerational Age Structure among Canadian Families

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    This paper examines intergenerational connections within Canadian families. Its focus is on intergenerational age structure, the interval or 'gap' in years that separates one generation from the next. Intergenerational age structure is measured in terms of the age of a mother at the birth of her first child. Using data from the 1995 General Social Survey of Canada, the study examines the socio-demographic characteristics of women (n=404) in three- and four-generation families (lineages) that are age-condensed (small age distances between generations that are the result of early fertility) and those that are age- gapped (with large age distances between generations that are the result of late fertility patterns). Across two generations of women, there is a striking similarity in the distributions of age at first birth with just under one-third of the sample having early fertility, just over one-half falling into a normative or "on-time" category, and one-seventh having delayed fertility. However, when matched pairs of mothers and daughters are compared across generations, age-condensed and age-gapped lineage patterns show considerable variability. Although just under one-half of mother-daughter dyads show lineage consistency in family age structure across three generations (most typically in age-condensed/age-condensed or normative/normative age structures), low percentages of women whose family of origin was age-gapped repeat that age structure pattern in their own families of procreation. Socio-demographic factors such as mother's and daughter's age, family size, age at first marriage, and level of education are associated with lineage continuity and discontinuity in family age structure.intergenerational age structure; GSS

    Pulsation models for the roAp star HD 134214

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    Precise time-series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD 134214. We have fitted the observed frequencies with theoretical frequencies of axisymmetric modes in a grid of stellar models with dipole magnetic fields. We find that, among models with a standard composition of (X,Z)=(0.70,0.02)(X,Z) = (0.70,0.02) and with suppressed convection, eigenfrequencies of a 1.65M1.65\,{\rm M}_\odot model with logTeff=3.858\log T_{\rm eff} = 3.858 and a polar magnetic field strength of 4.1kG agree best with the observed frequencies. We identify the observed pulsation frequency with the largest amplitude as a deformed dipole (=1\ell = 1) mode, and the four next-largest-amplitude frequencies as deformed =2\ell = 2 modes. These modes have a radial quasi-node in the outermost atmospheric layers (τ103\tau \sim 10^{-3}). Although the model frequencies agree roughly with observed ones, they are all above the acoustic cut-off frequency for the model atmosphere and hence are predicted to be damped. The excitation mechanism for the pulsations of HD 134214 is not clear, but further investigation of these modes may be a probe of the atmospheric structure in this magnetic chemically peculiar star.Comment: 9 pages, 6 figures; accepted for publication in MNRA

    A Luminous Companion to SGR 1806-20

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    We have obtained infrared spectra of the star suggested to be the counterpart of the soft gamma-ray repeater (SGR) 1806-20. We found strong emission lines similar to those seen in the spectra of the rare Luminous Blue Variables and B[e] stars. A He I absorption line is also seen, from which we infer a spectral type O9--B2. This classification, in combination with the minimum distance of \simgt6 kpc inferred from its extinction, makes the star one of the most luminous in the Galaxy. We infer that it is a companion to SGR 1806-20, and suggest that the presence of a companion is somehow related to the SGR phenomenon.Comment: 5 pages, AASTEX text+table and 2 PostScript figures (needs LaTeX style files aaspptwo.sty, epsf.sty and rotate.sty). In case of problems, contact [email protected]. Postscript file of complete article available on request. (Replaced because first version had one wrong reference in it

    STOP - A computer program for supersonic transport trajectory optimization

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    IBM 7094 digital program using steepest ascent technique for optimizing flight path of supersonic transport aircraf

    Technical pre-analytical effects on the clinical biochemistry of Atlantic salmon (Salmo salar L.)

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    Clinical biochemistry has long been utilized in human and veterinary medicine as a vital diagnostic tool, but despite occasional studies showing its usefulness in monitoring health status in Atlantic salmon (Salmo salar L.), it has not yet been widely utilized within the aquaculture industry. This is due, in part, to a lack of an agreed protocol for collection and processing of blood prior to analysis. Moreover, while the analytical phase of clinical biochemistry is well controlled, there is a growing understanding that technical pre-analytical variables can influence analyte concentrations or activities. In addition, post-analytical interpretation of treatment effects is variable in the literature, thus making the true effect of sample treatment hard to evaluate. Therefore, a number of pre-analytical treatments have been investigated to examine their effect on analyte concentrations and activities. In addition, reference ranges for salmon plasma biochemical analytes have been established to inform veterinary practitioners and the aquaculture industry of the importance of clinical biochemistry in health and disease monitoring. Furthermore, a standardized protocol for blood collection has been proposed

    Cosmic ray acceleration to ultrahigh energy in radio galaxies

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    The origin of ultrahigh energy cosmic rays (UHECRs) is an open question. In this proceeding, we first review the general physical requirements that a source must meet for acceleration to 10-100 EeV, including the consideration that the shock is not highly relativistic. We show that shocks in the backflows of radio galaxies can meet these requirements. We discuss a model in which giant-lobed radio galaxies such as Centaurus A and Fornax A act as slowly-leaking UHECR reservoirs, with the UHECRs being accelerated during a more powerful past episode. We also show that Centaurus A, Fornax A and other radio galaxies may explain the observed anisotropies in data from the Pierre Auger Observatory, before examining some of the difficulties in associating UHECR anisotropies with astrophysical sources.Comment: 6 pages, 4 figures. Proceedings of UHECR 2018, 8-12 October 2018, Paris, Franc

    Sonoporaton and Impedance Spectroscopy for the Assistance with and Observation of Development of Healthier Embryos and Fetuses.

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    M.S. Thesis. University of Hawaiʻi at Mānoa 2017

    Multiprotein DNA looping

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    DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switch-like transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.Comment: 11 pages, 4 figure

    Amplification of perpendicular and parallel magnetic fields by cosmic ray currents

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    Cosmic ray (CR) currents through magnetised plasma drive strong instabilities producing amplification of the magnetic field. This amplification helps explain the CR energy spectrum as well as observations of supernova remnants and radio galaxy hot spots. Using magnetohydrodynamic (MHD) simulations, we study the behaviour of the non-resonant hybrid (NRH) instability (also known as the Bell instability) in the case of CR currents perpendicular and parallel to the initial magnetic field. We demonstrate that extending simulations of the perpendicular case to 3D reveals a different character to the turbulence from that observed in 2D. Despite these differences, in 3D the perpendicular NRH instability still grows exponentially far into the non-linear regime with a similar growth rate to both the 2D perpendicular and 3D parallel situations. We introduce some simple analytical models to elucidate the physical behaviour, using them to demonstrate that the transition to the non-linear regime is governed by the growth of thermal pressure inside dense filaments at the edges of the expanding loops. We discuss our results in the context of supernova remnants and jets in radio galaxies. Our work shows that the NRH instability can amplify magnetic fields to many times their initial value in parallel and perpendicular shocks.Comment: Published in MNRAS. 14 pages, 12 figures, 2 tables. Replacement corrects some typesetting error
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