1,148 research outputs found

    Spectroscopic Monitoring Observations of Nova V1724 Aql in 2012

    Get PDF
    Spectroscopic and photometric monitoring observations of nova Apl 2012 (V1724 Apl) were conducted at Koyama Astronomical Observatory, Fujii-Kurosaki Observatory and Bisei Astronomical Observatory. The nova was initially considered as an outbursting pre-main-sequence young stellar object. Our monitoring observations have revealed the nova to be a Fe II type classical nova. The temporal evolution of spectra and light curves of the nova were similar to those of a slow nova (e.g., V1280 Sco and V5558 Sgr). We observed no evidence of molecule formation in V1724 Aql in contrast with V2676 Oph in which dust formation occurred after the molecular formation in the nova outflow

    Low- and Medium-Dispersion Spectropolarimetry of Nova V475 Sct (Nova Scuti 2003): Discovery of an Asymmetric High-Velocity Wind in a Moderately Fast Nova

    Full text link
    We present low-resolution (Rāˆ¼90R\sim 90) and medium-resolution (Rāˆ¼2500R\sim 2500) spectropolarimetry of Nova V475 Sct with the HBS instrument, mounted on the 0.91-m telescope at the Okayama Astrophysical Observatory, and with FOCAS, mounted on the 8.2-m Subaru telescope. We estimated the interstellar polarization toward the nova from the steady continuum polarization components and HĪ±\alpha line emission components. After subtracting the interstellar polarization component from the observations, we found that the HĪ±\alpha emission seen on 2003 October 7 was clearly polarized. In the polarized flux spectrum, the HĪ±\alpha emission had a distinct red wing extending to āˆ¼+4900\sim +4900 km sāˆ’1^{-1} and a shoulder around +3500+3500 km sāˆ’1^{-1}, showing a constant position angle of linear polarization \theta_{\rm *}\simeq 155\arcdeg\pm 15\arcdeg. This suggests that the nova had an asymmetric outflow with a velocity of vwindā‰ƒ3500v_{\rm wind}\simeq 3500 km sāˆ’1^{-1} or more, which is six times higher than the expansion velocity of the ionized shell at the same epoch. Such a high-velocity component has not previously been reported for a nova in the `moderately fast' speed class. Our observations suggest the occurrence of violent mass-loss activity in the nova binary system even during the common-envelope phase. The position angle of the polarization in the HĪ±\alpha wing is in good agreement with that of the continuum polarization found on 2003 September 26 (pāˆ—ā‰ƒ0.4p_{\rm *}\simeq 0.4--0.6 %), which disappeared within the following 2 d. The uniformity of the PA between the continuum polarization and the wing polarization on October 7 suggests that the axis of the circumstellar asymmetry remained nearly constant during the period of our observations.Comment: 27 pages, 7 figures, accepted for publication in A

    Methods for Reducing False Alarms in Searches for Compact Binary Coalescences in LIGO Data

    Get PDF
    The LIGO detectors are sensitive to a variety of noise transients of non-astrophysical origin. Instrumental glitches and environmental disturbances increase the false alarm rate in the searches for gravitational waves. Using times already identified when the interferometers produced data of questionable quality, or when the channels that monitor the interferometer indicated non-stationarity, we have developed techniques to safely and effectively veto false triggers from the compact binary coalescences (CBCs) search pipeline

    Reversing Blood Flows Act through klf2a to Ensure Normal Valvulogenesis in the Developing Heart

    Get PDF
    Heart valve anomalies are some of the most common congenital heart defects, yet neither the genetic nor the epigenetic forces guiding heart valve development are well understood. When functioning normally, mature heart valves prevent intracardiac retrograde blood flow; before valves develop, there is considerable regurgitation, resulting in reversing (or oscillatory) flows between the atrium and ventricle. As reversing flows are particularly strong stimuli to endothelial cells in culture, an attractive hypothesis is that heart valves form as a developmental response to retrograde blood flows through the maturing heart. Here, we exploit the relationship between oscillatory flow and heart rate to manipulate the amount of retrograde flow in the atrioventricular (AV) canal before and during valvulogenesis, and find that this leads to arrested valve growth. Using this manipulation, we determined that klf2a is normally expressed in the valve precursors in response to reversing flows, and is dramatically reduced by treatments that decrease such flows. Experimentally knocking down the expression of this shear-responsive gene with morpholine antisense oligonucleotides (MOs) results in dysfunctional valves. Thus, klf2a expression appears to be necessary for normal valve formation. This, together with its dependence on intracardiac hemodynamic forces, makes klf2a expression an early and reliable indicator of proper valve development. Together, these results demonstrate a critical role for reversing flows during valvulogenesis and show how relatively subtle perturbations of normal hemodynamic patterns can lead to both major alterations in gene expression and severe valve dysgenesis

    A new approach to chi^2 cryptanalysis of block ciphers

    Get PDF
    The main contribution of this paper is a new approach to Ļ‡2 analyses of block ciphers in which plaintexts are chosen in a manner similar to that in a square/saturation attack. The consequence is a faster detection of Ļ‡2 correlation when compared to conventional Ļ‡2 cryptanal- ysis. Using this technique we (i) improve the previously best-known Ļ‡2 attacks on 2- and 4-round RC6, and (ii) mount the ļ¬rst attacks on the MRC6 and ERC6 block ciphers. The analyses of these fast primitives were also motivated by their low diļ¬€usion power and, in the case of MRC6 and ERC6, their large block sizes, that favour their use in the construction of compression functions. Our analyses indicate that up to 98 rounds of MRC6 and 44 rounds of ERC6 could be attacked

    Human Gene and Protein Database (HGPD): a novel database presenting a large quantity of experiment-based results in human proteomics

    Get PDF
    Completion of human genome sequencing has greatly accelerated functional genomic research. Full-length cDNA clones are essential experimental tools for functional analysis of human genes. In one of the projects of the New Energy and Industrial Technology Development Organization (NEDO) in Japan, the full-length human cDNA sequencing project (FLJ project), nucleotide sequences of approximately 30 000 human cDNA clones have been analyzed. The Gateway system is a versatile framework to construct a variety of expression clones for various experiments. We have constructed 33 275 human Gateway entry clones from full-length cDNAs, representing to our knowledge the largest collection in the world. Utilizing these clones with a highly efficient cell-free protein synthesis system based on wheat germ extract, we have systematically and comprehensively produced and analyzed human proteins in vitro. Sequence information for both amino acids and nucleotides of open reading frames of cDNAs cloned into Gateway entry clones and in vitro expression data using those clones can be retrieved from the Human Gene and Protein Database (HGPD, http://www.HGPD.jp). HGPD is a unique database that stores the information of a set of human Gateway entry clones and protein expression data and helps the user to search the Gateway entry clones

    Stability and power optimality in time-periodic flapping wing structures

    Get PDF
    This paper investigates the nonlinear dynamics of a vehicle with two flexible flapping wings. The body dynamics and the wings\u27 deformation are monolithically grouped into a single system of equations, with aerodynamics accounted for by a quasi-steady blade element method. A periodic shooting method is then used to locate closed orbits of this non-autonomous system, and Floquet multipliers assess the linearized stability about the nonlinear orbit. This framework is then exposed to a gradient based optimizer, in order to quantify the role of wing planform variables, wing structure variables, and kinematic actuation variables in obtaining vehicles with superior open-loop stability characteristics, and/or low-power requirements
    • ā€¦
    corecore