2,884 research outputs found

    Cardiovascular effects of variations in habitual levels of physical activity

    Get PDF
    Mechanisms involved in human cardiovascular adaption to stress, particularly adaption to different levels of physical activity are determined along with quantitative noninvasive methods for evaluation of cardiovascular function during stess in normal subjects and in individuals with latent or manifest cardiovascular disease. Results are summarized

    Local starburst galaxies and their descendants

    Full text link
    Despite strong interest in the starburst (hereafter SB) phenomenon, the concept remains ill-defined. We use a strict definition of SB to examine the statistical properties of local SB and post-starburst (hereafter PB) galaxies. We also seek relationships to active galaxies. Potential SB galaxies are selected from the SDSS DR7 and their stellar content is analysed. We apply an age dependent dust attenuation correction and derive star formation rates (SFR), ages and masses of the young and old populations. The photometric masses nicely agree with dynamical masses derived from the H-alpha emission line width. To select SB galaxies, we use the birthrate parameter b=SFR/, requiring b>=3. The PB sample is selected from the citerion EW(Hdelta_abs)>=6 A. Only 1% of star-forming galaxies are found to be SB galaxies. They contribute 3-6% to the stellar production and are therefore unimportant for the local star formation activity. The median SB age is 70 Myr, roughly independent of mass. The b-parameter strongly depends on burst age. Values close to b=60 are found at ages ~10 Myr, while almost no SBs are found at ages >1 Gyr. The median baryonic burst mass fraction of sub-L* galaxies is 5%, decreasing slowly with mass. The median mass fraction of the recent burst in the PB sample is 5-10%. The age-mass distribution of the progenitors of the PBs is bimodal with a break at log(M)~10.6 above which the ages are doubled. The SB and PB luminosity functions (hereafter LFs) follow each other closely until M_r~-21, when AGNs begin to dominate. The PB LF continues to follow the AGN LF while SB loose significance. This suggests that the number of luminous SBs is underestimated by about one dex at high luminosities, due to large amounts of dust and/or AGN blending. It also indicates that the SB phase preceded the AGN phase. We also discuss the conditions for global gas outflow caused by stellar feedback.Comment: Accepted for publication in Astronomy and Astrophysics. This is an extended, substantially revised and corrected version with partly modified conclusion

    Nuclear prolate-shape dominance with the Woods-Saxon potential

    Full text link
    We study the prolate-shape predominance of the nuclear ground-state deformation by calculating the masses of more than two thousand even-even nuclei using the Strutinsky method, modified by Kruppa, and improved by us. The influences of the surface thickness of the single-particle potentials, the strength of the spin-orbit potential, and the pairing correlations are investigated by varying the parameters of the Woods-Saxon potential and the pairing interaction. The strong interference between the effects of the surface thickness and the spin-orbit potential is confirmed to persist for six sets of the Woods-Saxon potential parameters. The observed behavior of the ratios of prolate, oblate, and spherical nuclei versus potential parameters are rather different in different mass regions. It is also found that the ratio of spherical nuclei increases for weakly bound unstable nuclei. Differences of the results from the calculations with the Nilsson potential are described in detail.Comment: 16 pages, 17 figure

    Novel Magnet Production Technique Used for an Elliptically Polarizing Undulator

    Get PDF
    A common problem for elliptically polarizing undulators EPUs is that the magnetic forces give a mechanical deflection in the magnet holder construction when changing the undulator phase. Gluing horizontally and vertically magnetized blocks together can increase the mechanical stability of the magnet holders. The gluing process of pairs of magnetized magnet blocks is time consuming, expensive and difficult to carry out with high positional precision. A novel magnet production technique has been developed where un magnetized pairs of blocks are glued together before magnetization. The large number of parts, the time for assembly, and the cost of the EPU can be reduced with the novel magnet production technique. The novel magnet production method has been used for a 2.6 m long EPU of APPLE II type, which has been built in house at the MAX IV Laboratory. The frame for the EPU is made of cast iron in order to get a small mechanical deformation when changing phase in the inclined mode. The paper includes detailed descriptions of the novel magnet production technique, including measurements of the magnetization, and the new EP

    Similarity of nuclear structure in 132Sn and 208Pb regions: proton-neutron multiplets

    Full text link
    Starting from the striking similarity of proton-neutron multiplets in 134Sb and 210Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V-low-k approach. The calculated results for 136Sb, 212Bi, 136I, and 212At are in very good agreement with the available experimental data. The similarity between 132Sn and 208Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.Comment: 4 pages, 3 figures, 2 table

    Sulfatide in health and disease. The evaluation of sulfatide in cerebrospinal fluid as a possible biomarker for neurodegeneration

    Get PDF
    Sulfatide (3-O-sulfogalactosylceramide, SM4) is a glycosphingolipid, highly multifunctional and particularly enriched in the myelin sheath of neurons. The role of sulfatide has been implicated in various biological fields such as the nervous system, immune system, host-pathogen recognition and infection, beta cell function and haemostasis/thrombosis. Thus, alterations in sulfatide metabolism and production are associated with several human diseases such as neurological and immunological disorders and cancers. The unique lipid-rich composition of myelin reflects the importance of lipids in this specific membrane structure. Sulfatide has been shown to be involved in the regulation of oligodendrocyte differentiation and in the maintenance of the myelin sheath by influencing membrane dynamics involving sorting and lateral assembly of myelin proteins as well as ion channels. Sulfatide is furthermore essential for proper formation of the axo-glial junctions at the paranode together with axonal glycosphingolipids. Alterations in sulfatide metabolism are suggested to contribute to myelin deterioration as well as synaptic dysfunction, neurological decline and inflammation observed in different conditions associated with myelin pathology (mouse models and human disorders). Body fluid biomarkers are of importance for clinical diagnostics as well as for patient stratification in clinical trials and treatment monitoring. Cerebrospinal fluid (CSF) is commonly used as an indirect measure of brain metabolism and analysis of CSF sulfatide might provide information regarding whether the lipid disruption observed in neurodegenerative disorders is reflected in this body fluid. In this review, we evaluate the diagnostic utility of CSF sulfatide as a biomarker for neurodegenerative disorders associated with dysmyelination/demyelination by summarising the current literature on this topic. We can conclude that neither CSF sulfatide levels nor individual sulfatide species consistently reflect the lipid disruption observed in many of the demyelinating disorders. One exception is the lysosomal storage disorder metachromatic leukodystrophy, possibly due to the genetically determined accumulation of non-metabolised sulfatide. We also discuss possible explanations as to why myelin pathology in brain tissue is poorly reflected by the CSF sulfatide concentration. The previous suggestion that CSF sulfatide is a marker of myelin damage has thereby been challenged by more recent studies using more sophisticated laboratory techniques for sulfatide analysis as well as improved sample selection criteria due to increased knowledge on disease pathology

    Relativity and the lead-acid battery

    Full text link
    The energies of the solid reactants in the lead-acid battery are calculated ab initio using two different basis sets at non-relativistic, scalar relativistic, and fully relativistic levels, and using several exchange-correlation potentials. The average calculated standard voltage is 2.13 V, compared with the experimental value of 2.11 V. All calculations agree in that 1.7-1.8 V of this standard voltage arise from relativistic effects, mainly from PbO2 but also from PbSO4
    corecore