479 research outputs found

    Multiregional Population Projections

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    This paper is an exposition of the mathematics of multiregional population projection. We begin by outlining the notion of a multiregional life table. Next, we show how the stationary regional populations of such a life table serve as inputs to numerical calculations carried out with the multiregional versions of the discrete and continuous models of demographic growth. We then conclude with a brief consideration of some of the spatial consequences of zero population growth

    Increment-Decrement Life Tables: A Comment

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    In a recent paper, R. Schoen poses the problem of constructing a set of k interrelated increment-decrement life tables but presents explicit solutions only for two-table and three-table models. Here, we derive the k-table analogue of the single-table formula (Schoen's Eq. 11) and illustrate its use in a problem area not included in Schoen's list of potential applications, namely, multiregional life table construction. In this particular application, increments are due to in-migration and decrements result from out-migration

    Migration and Settlement: A Multiregional Comparative Study

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    In 1976, the International Institute for Applied Systems Analysis initiated a study of migration and population distribution patterns in its 17 member nations. In each country, the analysis was carried out by a national scholar using techniques of multiregional demography. This paper describes the organization of the study, discusses the data bases used, evaluates the main results obtained, and reviews some of the methodological research that has been generated by the study. Among the conclusions of the paper are recommendations for researchers wishing to carry out a multiregional demographic analysis

    Dispersal capacities of pollen, seeds and spores: insights from comparative analyses of spatial genetic structures in bryophytes and spermatophytes

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    Introduction: The dramatic fluctuations of climate conditions since the late Tertiary era have resulted in major species range shifts. These movements were conditioned by geographic barriers and species dispersal capacities. In land plants, gene flow occurs through the movement of male gametes (sperm cells, pollen grains), which carry nDNA, and diaspores (spores, seeds), which carry both cpDNA and nDNA, making them an ideal model to compare the imprints of past climate change on the spatial genetic structures of different genomic compartments. Based on a meta-analysis of cpDNA and nDNA sequence data in western Europe, we test the hypotheses that nDNA genetic structures are similar in bryophytes and spermatophytes due to the similar size of spores and pollen grains, whereas genetic structures derived from the analysis of cpDNA are significantly stronger in spermatophytes than in bryophytes due to the substantially larger size of seeds as compared to spores. Methods: Sequence data at 1-4 loci were retrieved for 11 bryophyte and 17 spermatophyte species across their entire European range. Genetic structures between and within southern and northern populations were analyzed through F and N statistics and Mantel tests. Results and discussion: Gst and Nst between southern and northern Europe derived from cpDNA were significantly higher, and the proportion of significant tests was higher in spermatophytes than in bryophytes. This suggests that in the latter, migrations across mountain ranges were sufficient to maintain a homogenous allelic structure across Europe, evidencing the minor role played by mountain ranges in bryophyte migrations. With nDNA, patterns of genetic structure did not significantly differ between bryophytes and spermatophytes, in line with the hypothesis that spores and pollen grains exhibit similar dispersal capacities due to their size similarity. Stronger levels of genetic differentiation between southern and northern Europe, and within southern Europe, in spermatophytes than in bryophytes, caused by higher long-distance dispersal capacities of spores as compared to seeds, may account for the strikingly higher levels of endemism in spermatophytes than in bryophytes in the Mediterranean biodiversity hotspot

    Migration and Urbanization in the Asian Pacific

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    The principal aim of this paper is to suggest two alternative methods for assessing the reasonableness of alternative sets of United Nations projections of population growth and urbanization. Both methods use models of urban population dynamics that are simple enough to be called transparent. The conclusion of the paper is that the most recent U.N. projections appear to be reasonable ones in the light of historical experience

    Transcriptomic effects of adenosine 2A receptor deletion in healthy and endotoxemic murine myocardium

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    Influences of adenosine 2A receptor (A2AR) activity on the cardiac transcriptome and genesis of endotoxemic myocarditis are unclear. We applied transcriptomic profiling (39 K Affymetrix arrays) to identify A2AR-sensitive molecules, revealed by receptor knockout (KO), in healthy and endotoxemic hearts. Baseline cardiac function was unaltered and only 37 A2AR-sensitive genes modified by A2AR KO (≥1.2-fold change, \u3c5 \u3e% FDR); the five most induced are Mtr, Ppbp, Chac1, Ctsk and Cnpy2 and the five most repressed are Hp, Yipf4, Acta1, Cidec and Map3k2. Few canonical paths were impacted, with altered Gnb1, Prkar2b, Pde3b and Map3k2 (among others) implicating modified G protein/cAMP/PKA and cGMP/NOS signalling. Lipopolysaccharide (LPS; 20 mg/kg) challenge for 24 h modified \u3e4100 transcripts in wild-type (WT) myocardium (≥1.5-fold change, FDR \u3c 1 %); the most induced are Lcn2 (+590); Saa3 (+516); Serpina3n (+122); Cxcl9 (+101) and Cxcl1 (+89) and the most repressed are Car3 (−38); Adipoq (−17); Atgrl1/Aplnr (−14); H19 (−11) and Itga8 (−8). Canonical responses centred on inflammation, immunity, cell death and remodelling, with pronounced amplification of toll-like receptor (TLR) and underlying JAK-STAT, NFκB and MAPK pathways, and a ‘cardio-depressant’ profile encompassing suppressed ß-adrenergic, PKA and Ca2+ signalling, electromechanical and mitochondrial function (and major shifts in transcripts impacting function/injury including Lcn2, S100a8/S100a9, Icam1/Vcam and Nox2 induction, and Adipoq, Igf1 and Aplnr repression). Endotoxemic responses were selectively modified by A2AR KO, supporting inflammatory suppression via A2AR sensitive shifts in regulators of NFκB and JAK-STAT signalling (IκBζ, IκBα, STAT1, CDKN1a and RRAS2) without impacting the cardio-depressant gene profile. Data indicate A2ARs exert minor effects in un-stressed myocardium and selectively suppress NFκB and JAK-STAT signalling and cardiac injury without influencing cardiac depression in endotoxemia

    In-depth mesocrystal formation analysis of microwave-assisted synthesis of LiMnPO4nanostructures in organic solution

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    In the present work, we report on the preparation of LiMnPO4 (lithiophilite) nanorods and mesocrystals composed of self-assembled rod subunits employing microwave-assisted precipitation with processing times on the time scale of minutes. Starting from metal salt precursors and H3PO4 as phosphate source, single-phase LiMnPO4 powders with grain sizes of approx. 35 and 65 nm with varying morphologies were obtained by tailoring the synthesis conditions using rac-1-phenylethanol as solvent. The mesocrystal formation, microstructure and phase composition were determined by electron microscopy, nitrogen physisorption, X-ray diffraction (including Rietveld refinement), dynamic light scattering, X-ray absorption and X-ray photoelectron spectroscopy, and other techniques. In addition, we investigated the formed organic matter by gas chromatography coupled with mass spectrometry in order to gain a deeper understanding of the dissolution\u2013precipitation process. Also, we demonstrate that the obtained LiMnPO4 nanocrystals can be redispersed in polar solvents such as ethanol and dimethylformamide and are suitable as building blocks for the fabrication of nanofibers via electrospinning

    Role for Neuronal Nitric-Oxide Synthase in Cannabinoid-Induced Neurogenesis

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    ABSTRACT Cannabinoids, acting through the CB1 cannabinoid receptor (CB1R), protect the brain against ischemia and related forms of injury. This may involve inhibiting the neurotoxicity of endogenous excitatory amino acids and downstream effectors, such as nitric oxide (NO). Cannabinoids also stimulate neurogenesis in the adult brain through activation of CB1R. Because NO has been implicated in neurogenesis, we investigated whether cannabinoid-induced neurogenesis, like cannabinoid neuroprotection, might be mediated through alterations in NO production. Accordingly, we measured neurogenesis in dentate gyrus (DG) and subventricular zone (SVZ) of CB1R-knockout (KO) and wild-type mice, some of whom were treated with the cannabi- or the NO synthase (NOS) inhibitor 7-nitroindazole (7-NI). NOS activity was increased by ϳ25%, whereas bromodeoxyuridine (BrdU) labeling of newborn cells in DG and SVZ was reduced by ϳ50% in CB1R-KO compared with wild-type mice. 7-NI increased BrdU labeling in both DG and SVZ and to a greater extent in CB1R-KO than in wild-type mice. In addition, R(ϩ)-Win 55212-2 and 7-NI enhanced BrdU incorporation into neuron-enriched cerebral cortical cultures to a similar maximal extent and in nonadditive fashion, consistent with a shared mechanism of action. Double-label confocal microscopy showed coexpression of BrdU and the neuronal lineage marker doublecortin (Dcx) in DG and SVZ of untreated and 7-NI-treated CB1R-KO mice, and 7-NI increased the number of Dcx-and BrdU/Dcx-immunoreactive cells in SVZ and DG. Thus, cannabinoids appear to stimulate adult neurogenesis by opposing the antineurogenic effect of NO. Cannabinoids, which include naturally occurring plantderived compounds [e.g., ⌬ 9 -tetrahydrocannabinol (THC)], endogenous signaling molecules found in animal brains (e.g., anandamide and 2-arachidonoylglycerol), and synthetic drugs [e.g., R(ϩ)-Win 55212-2)], act on receptors in the brain to modify neuronal function. In addition to their effects on normal physiological functions such as blood pressure, immunity, pain perception, appetite, and cognition, cannabinoids can also regulate the severity of brain injury. We reported previously that administration of cannabinoids acting on the CB1 cannabinoid receptor (CB1R) reduces neuronal death from cerebral ischemi
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