Double-hump Profiles Research Articles

Investigation of a likely orbital periodicity of Nova Hercules 2021 in X-rays and γ-rays

ABSTRACT We report a detection of a ∼0.153 d period in the classical nova V1674 Her using the NICER observations taken within a month since the outburst (i.e. ∼MJD 59405). The X-ray period is consistent with the orbital period previously found in the optical band, strongly suggesting the NICER signal as the X-ray orbital periodicity of the system. A seemingly double-humped profile was obtained by folding the detrended X-ray light curve with the period after removing the rotational X-ray pulsations of the nova. The profile may be caused by occultation by the companion or the accretion disc, possibly indicating a high inclination of the system. The γ-ray emission of V1674 Her with a significance level ≳ 5 σ was detected by Fermi-LAT close to its optical peak and the emission faded away within 1 d, which is the shortest duration known for a γ-ray nova. Folded on 0.153 d, a marginal γ-ray variability can be also seen in the LAT light curve, but without the double-hump feature observed in X-rays. If the γ-ray modulation is real, its origin is probably different from that observed in the X-ray and optical bands.

Nondegenerate N-soliton solutions for Manakov system

Recently, it has been proposed that solitons can be applied to increase the transmission rates in optical fibers. However due to their complex soliton solutions derived by Hirata method, it is pretty hard to study the properties of multiple nondegenerate solitons. In this paper, we investigate the general formula of nondegenerate N-soliton solutions for Manakov system by the Kadomtsev–Petviashvili (KP) hierarchy reduction. Based on the soliton solutions in determinant forms, different double-hump profiles of nondegenerate solitons are analyzed graphically with the consideration on their application in communication systems. The collisions between three nondegenerate solitons are studied via asymptotic analysis in detail. We further observe the collisions between two nondegenerate solitons and two normal single-hump solitons. We hope these results contribute to the study of soliton communication.

Photometric Analysis of the TESS Light Curve for the Asynchronous Polar V1500 Cyg

After 40 yr of nova outburst, there are still some difficulties in completely understanding V1500 Cyg. The faintness of V1500 Cyg and its crowded field pose a challenge for high-precision photometry by TESS, while long-term intensive data from TESS provide the first opportunity to accurately model this binary system. The best-fitting model reveals that the high-temperature white dwarf illuminates the surface of its companion star, a low-mass secondary (M 2 ∼ 0.22 M ⊙), and the emission from the heated secondary star still dominates the luminosity of the system. The binary model has determined the white dwarf’s mass to be M 1 ∼ 1.4 M ⊙ and its orbital inclination i ∼ 60°. The residuals after the removal of the fitted model curve present variations in both the white dwarf’s spin period and the binary orbital period, confirming the previous claim that V1500 Cyg is still an asynchronous polar, and the observed spin period demonstrates that V1500 Cyg is approaching synchronicity with the orbital period following the prediction of the polarization ephemeris. The phasing of the spin humps indicates their cyclotron origin, and the residual orbital humps may be produced by the emission from the accretion stream. There is no evidence for the pole-switching effect, while the double-humped profile of the spin modulation suggests that the white dwarf may be accreting matter from a “ring” around it. Further simultaneous polarization and X-ray observations are urged to explore the accretion geometry of V1500 Cyg in detail.

Vector bright soliton interactions of the two-component AB system in a baroclinic fluid

A two-component AB system, which describes the wave-packets in a baroclinic fluid, is investigated in this paper. Bright one- and two-soliton solutions are constructed via the Hirota method. We derive the degenerate and nondegenerate vector solitons associated with the one and two wave numbers, respectively, and the latter admit both the single- and double-hump profiles. Effects of the supercritical / subcritical coefficient μ and nonlinearity coefficient σ in that system on the wave packets A 1 and A 2 are analysed: Velocities of A 1 , A 2 and the wave-induced modification of the basic flow, B , are proportional to μ , amplitudes of A 1 and A 2 are inversely proportional to σ , and amplitude of B is proportional to μ . Via the asymptotic analysis, we find that (1) the interactions between the two degenerate solitons or two nondegenerate solitons can be elastic under certain conditions, otherwise the interactions are shape-changing with the total energy in each soliton (consisting of all the components) being conserved; (2) the interactions between the nondegenerate and degenerate solitons are shape-changing, and the nondegenerate solitons can remain the double-hump shape or change to the periodic oscillation after the interactions; (3) the energy redistribution between the A 1 and A 2 components occurs when the two degenerate solitons undergo the shape-changing interaction, and the nondegenerate soliton undergoes the interaction without any intensity redistribution.

Kinetic and Kinematic Analysis of Gait in Type IV Osteogenesis Imperfecta Patients: A Comparative Study

Background:Osteogenesis imperfecta (OI) is a genetic connective tissue disorder characterized by skeletal deformity and increased risk of fracture. Independent mobility is of concern for OI patients as it is associated with the quality of life. The present study investigates the variation of kinetic and kinematic gait parameters of type IV OI subjects and compares them with age-matched healthy subjects.Materials and Methods:Gait analysis is performed on five type IV OI patients and six age-matched normal subjects. Spatiotemporal, kinematic, and kinetic data are obtained using Helen Hayes marker placement protocol.Results:The results indicate an imprecise double-humped profile for vertical ground reaction force (GRF) with reduced ankle push off power and walking speed for OI subjects. Moreover, a comparison of vertical GRFs in OI subjects with that of healthy subjects suggests lower values for the former. The results encourage and motivate for further investigation with a bigger set of subjects.Conclusion:This information may be useful in developing a better understanding of pathological gait in type IV OI subjects, which ultimately helps the design of subject-specific implants, surgical preplanning, and rehabilitation.

On nonlinear dynamics of density wave oscillations in a channel with non-uniform axial heating

A few nonlinear dynamics (Hopf bifurcations and limit cycles) of density wave oscillations of a two-phase flow channel are studied in this work. The effects of different non-uniform axial heat flux profiles (found to be a key factor) on the aforesaid non-linear stability behavior of the system are shown which is missing in existing studies. The novel outcomes of this study are presented by the change in Hopf bifurcation phenomena as the heat flux pattern and other design parameters are varied even though the total heat rate remains same. The innovative aspect of this study can be explained by the use of a nodalized reduced order model (NROM). The time-dependent spatial variations of the flow variables (enthalpy and quality) are approximated in-line to the provided heat flux profiles and corresponding steady state solutions. On one hand, this scheme is capable of analyzing both linear and nonlinear stability characteristics of the system over a wide range of axial heat flux profiles. On the other hand, in this model the node positions are defined in such a way that they vary automatically during the system evolution as per the provided heat flux profile. Hence, it acts as an auto-adaptive scheme and helps to minimize the computational effort required to achieve significant accuracy to capture the state variable variations. A few unique findings of the present work are as follows: i) although non-uniform axial heat flux is more linearly stable compared to uniform axial heat flux profile, it is less non-linearly stable. ii) single humped axial heat profiles are more linearly stable than double humped profiles, but they become less non-linearly stable.

In vivo disposition and metabolism of madecassoside, a major bioactive constituent in Centella asiatica (L.) Urb.

Ethnopharmacological relevanceCentella asiatica (L.) Urb. herb is frequently used in traditional Chinese medicine for many indications, such as traumatic injuries, keloid and scar. Madecassoside is the main active ingredient of this herb drug with higher content than other triterpenoid constituents. Understandings of pharmacokinetic profiles of madecassoside should be beneficial for its development as a therapeutic agent. Materials and methodsSprague-Dawley rats were intravenously and orally administered madecassoside (100mg/kg), respectively. Plasma, heart, liver, spleen, lung, kidney, brain, bile, urine and feces were collected at the designed time points. Madecassoside concentrations in biological samples were determined by a sensitive and well-validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. A liquid chromatography coupled with time-of-flight mass spectrometry (LC-TOF-MS) method was established to identify its major metabolites in feces. To further pursue the disposition characteristics of madecassoside in rats, the involvement of the hepatobiliary efflux transporters in biliary elimination were studied by combination with digoxin (P-glycoprotein inhibitor) or probenecid (multidrug resistance-associated protein inhibitor). A linked-rat model was also used to assess the role of enterohepatic circulation in the pharmacokinetics of madecassoside. ResultsAfter a single oral dosing, madecassoside was widely distributed in heart, liver, spleen, lung and kidney of rats, and the levels of madecassoside in liver and kidney were relatively higher than other organs. The excretions of madecassoside in bile, urine and feces were 7.16% (0–12h), 0.25% (0–72h) and 24.68% (0–72h), respectively. The findings suggested that madecassoside might excrete mainly by metabolites. The combination with either digoxin or probenecid significantly attenuated the excretion of madecassoside as parent from bile, indicating that P-glycoprotein and multidrug resistance-associated protein might contribute to the hepatobiliary elimination of madecassoside. The presence of enterohepatic circulation, as implied by double-humped profiles in plasma and tissue concentration-time curves, was confirmed by a linked-rat model. Furthermore, three metabolities of madecassoside were indentified in rat feces and the possible metabolic pathways were proposed. ConclusionsThese findings provide valuable information regarding in vivo process of madecassoside, and help us to recognize the efficacy and safety of madecassoside itself, the relevant herbs or herbal preparations.

Metamorphosis of a Transition State into a Stable Species

Medium variations usually affect the shape of the bimolecular nucleophilic reaction profile at the reactants' and products' ends and, to a much lesser extent, the shape around the transition state. In water, the reactions of extended allylic systems such as F(-) + H-(CH=CH)n-CH2-F → F-CH2-(CH=CH)n-H + F(-) have been computationally shown (for n = 2) to have a single transition state. As the polarity is decreased the transition state is gradually transformed into a double-humped profile that then changes smoothly through a triple-well profile into a single-well profile where the symmetric structure of the transition state is retained. The depth of the well is ca. 16 kcal/mol for n = 2 and reaches 40 kcal/mol for n = 7, resembling the stability of a weak chemical bond. This is traced to electrostatic effects as well as to the effect of an intermediate VB configuration. In the analogous polyynes, a stable adduct is already formed at n = 1. This is attributed to the formation of the relatively stable vinylic carbanion. As the number of acetylene units increases, the vinylic geometry (a CCC angle of 123°) is gradually lost until at n = 5 the adduct attains a linear geometry.

Soliton solutions via auxiliary function method for a coherently-coupled model in the optical fiber communications

A coherently-coupled nonlinear Schrödinger system in the optical fiber communications, with the mixed self-phase modulation (SPM), cross-phase modulation (XPM) and positive coherent coupling terms, is studied through the bilinear method with an auxiliary function. Solutions for that system are found to be of two types: singular and non-singular ones, and the latter appear as the soliton-typed. Vector bright one- and two-solitons are derived with the corresponding phase-shift parameter constraints. In virtue of computerized symbolic computation and asymptotic behavior analysis, elastic collision mechanisms of such vector solitons are investigated. With the aid of graphical simulation, vector solitons are displayed to be of the single- or double-hump profiles. The formation and collision mechanisms of the vector bright solitons for that system are generated based on the combined effects of SPM, XPM and coherent coupling. Only elastic collisions of the vector solitons occur for that system, which is a distinctive feature amid those of other coherently-coupled nonlinear Schrödinger systems.

Multicomponent coherently coupled and incoherently coupled solitons and their collisions

We consider the integrable multicomponent coherently coupled nonlinear Schrödinger (CCNLS) equations describing simultaneous propagation of multiple fields in Kerr-type nonlinear media. The correct bilinear equations of m-CCNLS equations are obtained using a non-standard type of Hirota's bilinearization method, and the more general bright one solitons with single-hump and double-hump profiles including special flat-top profiles are obtained. The solitons are classified as coherently coupled solitons and incoherently coupled solitons depending upon the presence and absence of coherent nonlinearity arising due to the existence of the co-propagating modes/components. Further, the more general two-soliton solutions are obtained using this non-standard bilinearization approach, and various fascinating collision dynamics are pointed out. Particularly, we demonstrate that the collision between coherently coupled solitons and incoherently coupled solitons displays a non-trivial behaviour in which the former always undergoes energy switching accompanied by an amplitude-dependent phase-shift and change in the relative separation distance, leaving the latter unaltered. But the collision between coherently coupled solitons alone is found to be a standard elastic collision. Our study also reveals the important fact that the collision between incoherently coupled solitons arising in the m-CCNLS system with m = 2 is always elastic, whereas for m > 2 the collision becomes intricate, and for this case the m-CCNLS system exhibits interesting energy-sharing collision of solitons characterized by intensity redistribution, amplitude-dependent phase-shift and change in relative separation distance, which is similar to that of the multicomponent Manakov soliton collisions. This suggests that the m-CCNLS system can also be a suitable candidate for soliton collision-based optical computing in addition to the Manakov system.

V455 and – a life before the outburst

V455 And ( = HS 2331+3905) is a WZ Sge-type cataclysmic variable which shows a double-humped profile in its orbital light curve. It is also one of the few ZZ Cet pulsators among cataclysmic variables (CVs). In quiescence V455 And shows several types of variability in accordance with Araujo-Betancor et al. (2005). We present the results of observations of V455 And during the autumn seasons of the years 2004-2006, just before the superoutburst in 2007.

Gradient trajectory analysis of a scalar field with external intermittency

The passive scalar field of a temporally evolving shear layer is investigated using gradient trajectories as a means to analyse the scalar probability density function and the conditional scalar dissipation rate in the presence of external intermittency. These results are of significance for turbulent combustion, where improved predictions of the statistics of the conditional dissipation rate are needed in several models. First, the variation of the conventional first and second moments of the conditional dissipation rate across the layer is quantitatively documented in detail. A strong dependence of the conditional dissipation rate on the lateral position and on the conditioning value of the scalar is observed. The dependence on the transverse distance to the centre-plane partially explains the double-hump profile usually reported when this dependence is ignored. The variation with the scalar observed in the ratio between the second and first moments would invalidate certain assumptions commonly done in turbulent combustion. It is also seen that conditioning on the scalar does not reduce the fluctuation of the dissipation rate with respect to unconditional values. Next, the role of external intermittency in these results is investigated. For that purpose, the flow is partitioned into different zones based on different types of gradient trajectories passing through each point, thereby introducing non-local information in comparison with the standard turbulent/non-turbulent separation based on the conventional intermittency function. In addition to the homogeneous outer regions, three zones are identified: a turbulent zone, a turbulence interface and quasi-laminar diffusion layers. The relative contribution from each of these zones to the conventional intermittency factor is reported. The statistics are then conditioned on each of these zones, and the spatial variation of the scalar distribution and of the conditional scalar dissipation rate is explained in terms of the observed zonal statistics. For the Reynolds numbers of the present simulation, between 1500 and 3000 based on the vorticity thickness and the velocity difference, and a Schmidt number equal to 1, it results that the major contribution to both statistics is due to the turbulence interfaces. At the same time, the turbulent zone shows a distinct behaviour, being approximately homogeneous but anisotropic.

On the magnetic accretor GK Persei in outburst

RXTE made 5 X-ray observations of the magnetic accretor GK Per during its 1996 outburst, recording a count rate of ten times the quiescent level. The 351-s spin pulse shows a deep, nearly sinusoidal modulation, in contrast to the weaker, double-humped profile of quiescence. The spectrum shows absorption increased by two orders of magnitude over quiescence. We explain these differences in terms of the changing accretion geometry as the outbursting disc forces the magnetosphere inwards, and discuss the 5000-s X-ray QPOs seen during GK Per's outbursts.

사출/압축 성형 Center-Gated 디스크에서의 잔류 응력과 복굴절의 수치 해석 (I) - 모델링 및 기본 결과 -

The present study has numerically predicted both the flow -induced and thermally-induced residual stresses and birefringence in injection or injection/compression molded center -gated disks. Analysis system for entire molding process was developed based on an appropriate physical modeling including a nonlinear viscoelastic fluid model. stress-optical law. a linear viscoelastic solid model, free volume theory for density relaxation phenomena and a photoviscoelasticity and so on. Part I presents physical modeling and typical numerical analysis results of residual stresses and birefringence in the injection molded center -gated disk. Thermal residual stress was found to be extensional near the center, compressive near the surface and tend to become toward tensional at the surface. A double-hump profile was obtained across the thickness in birefringence distribution: nonzero birefringence is found to be thermally induced. the outer peak is due to the shear flow and subsequent stress relaxation during the filling stage and the inner peak is due to the additional shear flow and stress relaxation during the packing stage. Predicted birefringence including both the flow -induced and thermally-induced one becomes quite similar to the experimental one.

Electronic Structure of the Fluorinated Fullerene C60F48

The electronic structure of the fluorinated fullerene C60F48 has been studied by X-ray fluorescence spectroscopy. The C Kα spectrum of the compound has the double-humped profile with the well-defined high-energy shoulder. To interpret the C Kα spectrum and investigate the chemical bonding of C60F48, a chiral structure of D3 symmetry was calculated at the ab initio Hartree−Fock (HF) level using the 6-31G basis set. The electron density from the highest occupied molecular orbitals (HOMOs) of the D3 isomer is mainly localized on the carbon double bonds, and the contribution of 2p electrons of the fluorinated carbon atoms to these orbitals is also noticeable. The high-energy shoulder on the C Kα spectrum was shown to correspond to the electron transitions from HOMOs of C60F48 to 1s orbital vacancies of the carbon atoms attached to the fluorine atoms, and therefore the occurrence of this shoulder does not relate to the number of π electrons in the molecule. The molecular orbital structure of C60F48 was schematized as a set of blocks; the MOs were distinguished by the type of the chemical bonding between the atoms. Such orbital separation allowed a successful interpretation of the main features of the ultraviolet photoelectron spectrum of the fluorinated fullerene C60F48.

The Quiescent Accretion Disk in IP Pegasi at Near‐Infrared Wavelengths

We present near-infrared, H-band (1.45-1.85 μm) observations of an eclipsing dwarf nova, IP Peg, in quiescence. The light curves are composed of ellipsoidal variations from the late-type secondary star and emission from the accretion disk and the bright spot. The light curves have two eclipses: a primary eclipse of the accretion disk and the bright spot by the companion star, and a secondary eclipse of the companion star by the disk. The ellipsoidal variations of the secondary star were modeled and subtracted from the data. The resulting light curve shows a pronounced double-hump variation. The double-hump profile resembles those seen in the light curves of WZ Sge and AL Com and likely originates in the accretion disk. The primary eclipse was modeled using maximum entropy disk mapping techniques. The accretion disk has a flat intensity distribution and a cool brightness temperature (Tbr 3000 K) in the near-infrared. Superimposed on the face of the disk is the bright spot (Tbr 10,000 K); the position of the bright spot is different from the observed range of visible bright spot positions. The near-infrared accretion disk flux is dominated by optically thin emission. The secondary eclipse indicates the presence of some occulting medium in the disk, but the eclipse depth is too shallow to be caused by a fully opaque accretion disk.

Discovery of Two Types of Superhumps in WZ Sge-Type Dwarf Nova AL Comae Berenices

Abstract A dwarf nova, AL Com, was photometrically observed during an outburst in 1995 April, which occurred for the first time since 1975. The star showed two distinct types of periodic variation: (1) a 0.05666-day variation with decaying amplitudes during the earliest stage of the outburst, and (2) 0.0572-day super humps which grew ∼ 11 d after the onset of the outburst. The present observations are the one first to clearly established the SU UMa-type nature of AL Com. Furthermore, the appearance of these two periods, together with the whole course of the superoutburst, makes AL Com an almost perfect twin of an enigmatic dwarf nova, WZ Sge. We attributed the former period to be the orbital period of this cataclysmic binary. The double-humped profile of this variation seems to preclude an explantion based on an enhanced hot spot by a mass-transfer burst from the secondary, which has been believed to be the best observational evidence of a mass-transfer burst in WZ Sge obtained during its 1978 outburst.

Effects of double-humped axial heat flux variation on the stability of two-phase flow in heated channels

Stability analysis of two-phase flow in heated channels with double-humped axial heat flux variation, relevant to boiling water nuclear reactors, has been carried out. Single-phase and two-phase flow equations are linearized about the steady-state solution, and the stability of the fixed points is studied in frequency domain. Effects of symmetric and asymmetric double-humped axial heat flux variation on stability has been determined. Results are presented as stability boundaries in parameter space and as bifurcation diagrams. It is found that whether a channel with single-humped heat flux variation becomes more or less stable as the heat flux is replaced by an equivalent double-humped profile, actually depends upon other system parameters, such as the channel inlet subcooling. For example, for low inlet subcooling, a channel with symmetric double-humped heat flux variation is less stable than another channel with single-humped heat flux variation (same total heat flux), whereas, the trend is reversed for high inlet subcooling.

Quasar H profiles and discs

High signal-to-noise spectra of the Hβ region of eight radio-loud quasars are presented in an investigation seeking evidence for the emission of this line from a disc. Although no double-humped profile was found expected in simple versions of the disc hypothesis, no shoulders in the profile expected in a modified form of this idea was found. A model in which the radiation is scattered back from above the disc plane can reproduce the observed spectra provided that the disc is sufficiently large. Whether this model can explain why other Hβ profiles are shoulderless, and whether it is consistent with variability data are discussed.