4,180 research outputs found

    Multi-Epoch VLBA Observations of the Compact Wind-Collision Region in the Quadruple System Cyg OB2 #5

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    We present multi--epoch VLBA observations of the compact wind collision region in the Cyg OB2 #5 system. These observation confirm the arc-shaped morphology of the emission reported earlier. The total flux as a function of time is roughly constant when the source is "on", but falls below the detection limit as the wind collision region approaches periastron in its orbit around the contact binary at the center of the system. In addition, at one of the "on" epochs, the flux drops to about a fifth of its average value. We suggest that this apparent variation could result from the inhomogeneity of the wind that hides part of the flux rather than from an intrinsic variation. We measured a trigonometrical parallax, for the most compact radio emission of 0.61 ±\pm 0.22 mas, corresponding to a distance of 1.65 0.44+0.96^{+0.96}_{-0.44} kpc, in agreement with recent trigonometrical parallaxes measured for objects in the Cygnus X complex. Using constraints on the total mass of the system and orbital parameters previously reported in the literature, we obtain two independent indirect measurements of the distance to the Cyg OB2 #5 system, both consistent with 1.3--1.4 kpc. Finally, we suggest that the companion star responsible for the wind interaction, yet undetected, is of spectral type between B0.5 to O8.Comment: manuscript format, 24 pages, 5 figures, accepted for publication in The Astrophysical Journa

    Measuring Energy Expenditure and Heart Rate during Maximum Aerobic Testing with the Apple Watch Series 7

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    Introduction: Wrist-worn devices such as the Apple Watch have emerged as technology for tracking physical activity. The aim of this research study is to analyze the Apple Watch Series 7 (AW7) with measurements of the maximum heart rate (MHR) and maximum energy expenditure (MEE) during a maximal aerobic capacity test on the treadmill. AW7 measurements will be compared to the Polar Heart Rate Monitor (Polar) and the PARVO Metabolic Cart (PARVO). Methods: 22 healthy and active subjects (mean ± SD: age 23.8 ± 4.0 years; BMI 23.0 ± 5.9 kg/m2 ) volunteered for the study. The subjects confirmed their activity, health status, and were measured for body composition and aerobic capacity. Results: No significant difference was found in MEE between PARVO (109.6 ± 41.7 kcal) and AW7 (98.7 ± 24.3 kcal) conditions; t(21)=1.5, p = 0.153. In addition, there was no significant difference in MHR between PARVO (186.2 ± 16.2 BPM) and AW7 (189.3 ± 8.5 BPM) conditions; t(21)=-0.9, p = 0.379. Conclusions: The main findings of this study show that the MEE as well as the MHR between the AW7 compared to the PARVO are not different

    The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball Spectroscopy

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    On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyze this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multi-station meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute mag. -10.5) that was simultaneously imaged from three SPMN meteor ob-serving stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration, and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for 5 October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Society. Accepted for publication in MNRAS on April 28th, 2013 Manuscript Pages: 28 Tables: 5 Figures: 12. Manuscript associated: "The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth" by Trigo-Rodriguez et al. is also in press in the same journa

    Pilot Study on the Efficiency of the Biostimulation with Autologous Plasma Rich in Platelet Growth Factors in Otorhinolaryngology: Otologic Surgery (Tympanoplasty Type I)

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    When otologic procedures that involve tympanic membrane repairs are performed, biomaterials or biological tissues as normal as grafts are used. At the moment, biological material from the own patient is used with varying success rates. The procedure used and the patient's tissue repair capabilities tend to determine the outcome. We present a preliminary study on tympanic membrane perforation repairs using an autograft obtained by manipulating platelet degranulation and the coagulation cascade and reinforced with a seal using platelet growth factors. We present three cases in which we used this procedure. The results will be valued based on the tympanic perforation closure index. With this study, we want to assess the effectiveness of tympanic perforation repairs with this technically simple method. If this method was objectively proved to be effective, it would lead to lower patient morbidity and sanitary costs

    Beyond conventional factorization: Non-Hermitian Hamiltonians with radial oscillator spectrum

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    The eigenvalue problem of the spherically symmetric oscillator Hamiltonian is revisited in the context of canonical raising and lowering operators. The Hamiltonian is then factorized in terms of two not mutually adjoint factorizing operators which, in turn, give rise to a non-Hermitian radial Hamiltonian. The set of eigenvalues of this new Hamiltonian is exactly the same as the energy spectrum of the radial oscillator and the new square-integrable eigenfunctions are complex Darboux-deformations of the associated Laguerre polynomials.Comment: 13 pages, 7 figure

    Insulin and GLP-1 infusions demonstrate the onset of adipose-specific insulin resistance in a large fasting mammal: potential glucogenic role for GLP-1.

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    Prolonged food deprivation increases lipid oxidation and utilization, which may contribute to the onset of the insulin resistance associated with fasting. Because insulin resistance promotes the preservation of glucose and oxidation of fat, it has been suggested to be an adaptive response to food deprivation. However, fasting mammals exhibit hypoinsulinemia, suggesting that the insulin resistance-like conditions they experience may actually result from reduced pancreatic sensitivity to glucose/capacity to secrete insulin. To determine whether fasting results in insulin resistance or in pancreatic dysfunction, we infused early- and late-fasted seals (naturally adapted to prolonged fasting) with insulin (0.065 U/kg), and a separate group of late-fasted seals with low (10 pM/kg) or high (100 pM/kg) dosages of glucagon-like peptide-1 (GLP-1) immediately following a glucose bolus (0.5g/kg), and measured the systemic and cellular responses. Because GLP-1 facilitates glucose-stimulated insulin secretion, these infusions provide a method to assess pancreatic insulin-secreting capacity. Insulin infusions increased the phosphorylation of insulin receptor and Akt in adipose and muscle of early and late fasted seals; however the timing of the signaling response was blunted in adipose of late fasted seals. Despite the dose-dependent increases in insulin and increased glucose clearance (high dose), both GLP-1 dosages produced increases in plasma cortisol and glucagon, which may have contributed to the glucogenic role of GLP-1. Results suggest that fasting induces adipose-specific insulin resistance in elephant seal pups, while maintaining skeletal muscle insulin sensitivity, and therefore suggests that the onset of insulin resistance in fasting mammals is an evolved response to cope with prolonged food deprivation
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