The SW Sex-type star 2MASS J01074282+4845188: an unusual bright accretion disk with non-steady emission and a hot white dwarf

We present new photometric and spectral observations of the newly discovered nova-like eclipsing star 2MASS J01074282+4845188. To obtain a light curve solution we used model of a nova-like star whose emission sources are a white dwarf surrounded by an accretion disk, a secondary star filling its Roche lobe, a hot spot and a hot line. 2MASS J01074282+4845188 shows the deepest permanent eclipse among the known nova-like stars. It is reproduced by covering the very bright accretion disk by the secondary component. The luminosity of the disk is much bigger than that of the rest light sources. The determined high temperature of the disk is typical for that observed during the outbursts of CVs. The primary of 2MASS J01074282+4845188 is one of the hottest white dwarfs in CVs. The temperature of 5090 K of its secondary is also quite high and more appropriate for a long-period SW Sex star. It might be explained by the intense heating from the hot white dwarf and the hot accretion disk of the target. The high mass accretion rate \dot{M} = 8\times 10^{-9} M_{\sun} yr$^{-1}$, the broad and single-peaked H$\alpha$ emission profile, and the presence of an S-wave are sure signs for the SW Sex classification of 2MASS J01074282+4845188. The obtained flat temperature distribution along the disk radius as well as the deviation of the energy distribution from the black-body law are evidence of the non-steady emission of the disk. The close values of the disk temperature and the parameter $\alpha_{g}$ of 2MASS J01074282+4845188 and those of the cataclysmic stars at eruptions might be considered as an additional argument for the permanent active state of nova-like stars.Comment: 11 pages, 11 figures, 5 tables. Accepted for publication in A&

Nonlinear Terms of MHD Equations for Homogeneous Magnetized Shear Flow

We have derived the full set of MHD equations for incompressible shear flow of a magnetized fluid and considered their solution in the wave-vector space. The linearized equations give the famous amplification of slow magnetosonic waves and describe the magnetorotational instability. The nonlinear terms in our analysis are responsible for the creation of turbulence and self-sustained spectral density of the MHD (Alfven and pseudo-Alfven) waves. Perspectives for numerical simulations of weak turbulence and calculation of the effective viscosity of accretion disks are shortly discussed in k-space.Comment: 13 pages, no figures; AIP Conference Proceedings 1356, Proceedings of the School and Workshop on Space Plasma Physics (1--12 September 2010, Kiten, Bulgaria), American Institute of Physics, Melville, NY, 201

2MASSJ22560844+5954299: the newly discovered cataclysmic star with the deepest eclipse

Context: The SW Sex stars are assumed to represent a distinguished stage in CV evolution, making it especially important to study them. Aims: We discovered a new cataclysmic star and carried out prolonged and precise photometric observations, as well as medium-resolution spectral observations. Modelling these data allowed us to determine the psysical parameters and to establish its peculiarities. Results: The newly discovered vataclysmic variable 2MASSJ22560844+5954299 shows the deepest eclipse amongst the known nova-like stars. It was reproduced by totally covering a very luminous accretion disk by a red secondary component. The temperature distribution of the disk is flatter than that of steady-state disk. The target is unusual with the combination of a low mass ratio q~1.0 (considerably below the limit q=1.2 of stable mass transfer of CVs) and an M-star secondary. The intensity of the observed three emission lines, H_alpha, He 5875, and He 6678, sharply increases around phase 0.0, accompanied by a Doppler jump to the shorter wavelength. The absence of eclipses of the emission lines and their single-peaked profiles means that they originate mainly in a vertically extended hot-spot halo. The emission H_alpha line reveals S-wave wavelength shifts with semi-amplitude of around 210 km/s and phase lag of 0.03. Conclusions: The non-steady-state emission of the luminous accretion disk of 2MASSJ22560844+5954299 was attributed to the low viscosity of the disk matter caused by its unusually high temperature. The star shows all spectral properties of an SW Sex variable apart from the 0.5 central absorption.Comment: Accepted for publication in Astronomy & Astrophysics. 12 pages, 11 figures, 6 table

Thermal Breakage and Self-Healing of a Polymer Chain under Tensile Stress

We consider the thermal breakage of a tethered polymer chain of discrete segments coupled by Morse potentials under constant tensile stress. The chain dynamics at the onset of fracture is studied analytically by Kramers-Langer multidimensional theory and by extensive Molecular Dynamics simulations in 1D- and 3D-space. Comparison with simulation data in one- and three dimensions demonstrates that the Kramers-Langer theory provides good qualitative description of the process of bond-scission as caused by a {\em collective} unstable mode. We derive distributions of the probability for scission over the successive bonds along the chain which reveal the influence of chain ends on rupture in good agreement with theory. The breakage time distribution of an individual bond is found to follow an exponential law as predicted by theory. Special attention is focused on the recombination (self-healing) of broken bonds. Theoretically derived expressions for the recombination time and distance distributions comply with MD observations and indicate that the energy barrier position crossing is not a good criterion for true rupture. It is shown that the fraction of self-healing bonds increases with rising temperature and friction.Comment: 25 pages, 13 picture

Eccentric Contraction-Induced Muscle Fibre Adaptation

Hard-strength training induces strength increasing and muscle damage, especially after eccentric contractions. Eccentric contractions also lead to muscle adaptation. Symptoms of damage after repeated bout of the same or similar eccentrically biased exercises are markedly reduced. The mechanism of this repeated bout effect is unknown. Since electromyographic (EMG) power spectra scale to lower frequencies, the adaptation is related to neural adaptation of the central nervous system (CNS) presuming activation of slow-non-fatigable motor units or synchronization of motor unit firing. However, the repeated bout effect is also observed under repeated stimulation, i.e. without participation of the CNS. The aim of this study was to compare the possible effects of changes in intracellular action potential shape and in synchronization of motor units firing on EMG power spectra. To estimate possible degree of the effects of central and peripheral changes, interferent EMG was simulated under different intracellular action potential shapes and different degrees of synchronization of motor unit firing. It was shown that the effect of changes in intracellular action potential shape and muscle fibre propagation velocity (i.e. peripheral factors) on spectral characteristics of EMG signals could be stronger than the effect of synchronization of firing of different motor units (i.e. central factors)

Product and process innovations by means of rapid technologies

Published ArticleOver the past few years, methods of layered manufacturing (LM) have advanced substantially to the point where they now provide vital strategic benefits to various organisations. One area of application where LM technologies have begun to reach a critical mass is in the development and production of high-performance tooling in different forming processes. With these tooling capabilities now available, the next challenge becomes the development of optimal process chains to minimise lead times and production costs, while still ensuring high quality of castings. The relevant issues that influence where a break-even point will be between different process chains and thereby also the point of selection between such optimal process chains according to different situations include among others: the size of production runs, part size and complexity, and the cast materials involved. This paper reflects some of the experiences gained from an investigation towards developing a set of generic rules (guidelines) for the design of optimal process chains for sand casting prototypes of automotive components using LM methods, and more specifically the 3D Printing process

The importance of submalleolar deformity in determining leg length discrepancy

Background and purposeThe association of leg length discrepancy (LLD) with a number of clinical disorders has made its determination a significant part of the physical examination. We believe that submalleolar causes of LLD may be under-acknowledged. The most common clinical method used to measure LLD is by tape from the anterior superior iliac spine (ASIS) to medial malleolus which disregards the potential for LLD arising from asymmetry in the foot distal to the tibiotalar joint.MethodsThe present pilot study involves a group of 5 volunteers (experimental group) and a group of 3 patients with flexible flat feet (clinical study). The differences in tibial tubercle height from the ground between full pronation and full supination were measured using the CODA MPX 30® system (Charnwood Dynamics Limited, Leicestershire, England). Correlations of the patterns within each group were produced.ResultsA significant relationship with leg lengths was found in the experimental group when they induced maximum pronation (R-squared = 0.62, p = 0.007) while an inverse relationship occurred with supination, although marginally significant (R-squared = 0.37, p = 0.064).ConclusionsWe have demonstrated that significant leg length discrepancy can occur in patients who do not have obvious deformity when non weight bearing. We recommend using the blocks method routinely. Appropriately measuring LLD is of vital importance to properly diagnosing and treating patients with unequal leg lengths or related symptoms

CLINICO-MICROBIOLOGICAL DIAGNOSIS OF REACTIVE ARTHRITIS

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