563 research outputs found

    Magnetic field of Mercury confirmed

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    A contention that Mercury possesses an intrinsic magnetic field sufficient to deflect the solar wind flow was confirmed by the Mariner 10 experiment. Predictions made as to the locations where characteristic bow shock and magnetopause boundaries may be observed were also confirmed

    The magnetic field of Mercury, part 1

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    An updated analysis and interpretation is presented of the magnetic field observations obtained during the Mariner 10 encounter with the planet Mercury. The combination of data relating to position of the detached bow shock wave and magnetopause, and the geometry and magnitude of the magnetic field within the magnetosphere-like region surrounding Mercury, lead to the conclusion that an internal planetary field exists with dipole moment approximately 5.1 x 10 the 22nd power Gauss sq cm. The dipole axis has a polarity sense similar to earth's and is tilted 7 deg from the normal to Mercury's orbital plane. The magnetic field observations reveal a significant distortion of the modest Hermean field (350 Gamma at the equator) by the solar wind flow and the formation of a magnetic tail and neutral sheet which begins close to the planet on the night side. The composite data is not consistent with a complex induction process driven by the solar wind flow

    Magnetic field observations near Mercury: Preliminary results from Mariner 10

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    Results are presented from a preliminary analysis of data obtained near Mercury by the NASA/GSFC Magnetic Field Experiment on Mariner 10. A very well developed, detached bow shock wave, which developed as the super-Alfvenic solar wind interacted with the planet Mercury was observed. A magnetosphere-like region, with maximum field strength of 98 gamma at closest approach (704 km altitude) was also observed, and was contained within boundaries similar to the terrestrial magnetopause. The obstacle deflecting the solar wind flow was global in size, but the origin of the enhanced magnetic field was not established. The most plausible explanation, considering the complete body of data, favored the conclusion that Mercury has an intrinsic magnetic field

    Regulation of the hTERT telomerase catalytic subunit by the c-Abl tyrosine kinase

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    BACKGROUND: Telomeres consist of repetitive (TTAGGG) DNA sequences that are maintained by the multisubunit telomerase ribonucleoprotein. Telomerase consists of an RNA, which serves as template for the sequence tracts, and a catalytic subunit that functions in reverse transcription of the RNA template. Cloning and characterization of the human catalytic subunit of telomerase (hTERT) has supported a role in cell transformation. How telomerase activity is regulated, however, is largely unknown. RESULTS: We show here that hTERT associates directly with the c-Abl protein tyrosine kinase. We also found that c-Abl phosphorylates hTERT and inhibits hTERT activity. Moreover, our findings demonstrate that exposure of cells to ionizing radiation induces tyrosine phosphorylation of hTERT by a c-Abl-dependent mechanism. The functional significance of the c-Abl-hTERT interaction is supported by the demonstration that cells deficient in c-Abl show telomere lengthening. CONCLUSIONS: The ubiquitously expressed c-Abl tyrosine kinase is activated by DNA double-strand breaks. Our finding of telomere lengthening in c-Abl-deficient cells and the functional interactions between c-Abl and hTERT support a role for c-Abl in the regulation of telomerase function

    Viscous-Inviscid Interactions in a Boundary-Layer Flow Induced by a Vortex Array

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    In this paper we investigate the asymptotic validity of boundary layer theory. For a flow induced by a periodic row of point-vortices, we compare Prandtl's solution to Navier-Stokes solutions at different ReRe numbers. We show how Prandtl's solution develops a finite time separation singularity. On the other hand Navier-Stokes solution is characterized by the presence of two kinds of viscous-inviscid interactions between the boundary layer and the outer flow. These interactions can be detected by the analysis of the enstrophy and of the pressure gradient on the wall. Moreover we apply the complex singularity tracking method to Prandtl and Navier-Stokes solutions and analyze the previous interactions from a different perspective

    The influence of depression on risk development of acute cardiovascular diseases in the female population aged 25–64 in Russia

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    Background. Recent studies showed that depression was an independent predictor of mortality from cardio-vascular disease in healthy women. Objective. To explore the effect of depression (D) on relative risk (RR) of myocardial infarction (MI) and stroke for 16 years (1995–2010) in the female population aged 25–64 years from Novosibirsk, Russia. Materials and methods. Under the third screening of the WHO “MONICA-psychosocial” (MOPSY) programme, a cohort of women aged 25–64 years (N=560) was surveyed. Women were followed for 16 years for the incidence of MI and stroke (1995–2010). D was measured at the baseline examination by means of test “MOPSY”. Participants having stroke, MI, arterial hypertension, coronary artery diseases and diabetes in their medical history at the baseline were excluded from this analysis. Results. The prevalence of D in women aged 25–64 years was 55.2%. With the growth of D levels, positive self-rated health reduced and almost 100% of those women have complaints about their health, but considered the care of their health insufficient. Women with major D significantly extended negative behavioural habits: smoking and unsuccessful attempts to give up, low physical activity, and less likely to follow a diet (healthy food). Major D associated with high job strain and family stress. Relative risk (RR) of MI development in women with D during 16 years of study was higher in 2.53 cases (p<0.05) and risk of stroke was higher in 4.63 cases (p<0.05). Conclusions. The prevalence of D in women aged 25–64 years was >50%. Women with D had a 2.53-fold risk of MI and 4.63-fold risk of stroke during the 16 years of follow-up
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