An Imaging and Spectral Study of Ten X-Ray Filaments around the Galactic Center

We report the detection of 10 new X-ray filaments using the data from the {\sl Chandra} X-ray satellite for the inner $6^{\prime}$ ($\sim 15$ parsec) around the Galactic center (GC). All these X-ray filaments are characterized by non-thermal energy spectra, and most of them have point-like features at their heads that point inward. Fitted with the simple absorbed power-law model, the measured X-ray flux from an individual filament in the 2-10 keV band is $\sim 2.8\times10^{-14}$ to $10^{-13}$ ergs cm$^{-2}$ s$^{-1}$ and the absorption-corrected X-ray luminosity is $\sim 10^{32}-10^{33}$ ergs s$^{-1}$ at a presumed distance of 8 kpc to the GC. We speculate the origin(s) of these filaments by morphologies and by comparing their X-ray images with the corresponding radio and infrared images. On the basis of combined information available, we suspect that these X-ray filaments might be pulsar wind nebulae (PWNe) associated with pulsars of age $10^3 \sim 3\times 10^5$ yr. The fact that most of the filament tails point outward may further suggest a high velocity wind blowing away form the GC.Comment: 29 pages with 7 figures and 3 pages included. Accepted to Ap

Global axisymmetric stability analysis for a composite system of two gravitationally coupled scale-free discs

In a composite system of gravitationally coupled stellar and gaseous discs, we perform linear stability analysis for axisymmetric coplanar perturbations using the two-fluid formalism. The background stellar and gaseous discs are taken to be scale-free with all physical variables varying as powers of cylindrical radius $r$ with compatible exponents. The unstable modes set in as neutral modes or stationary perturbation configurations with angular frequency $\omega=0$.Comment: 7 pages using AAS styl

Stabilization of nonlinear velocity profiles in athermal systems undergoing planar shear flow

We perform molecular dynamics simulations of model granular systems undergoing boundary-driven planar shear flow in two spatial dimensions with the goal of developing a more complete understanding of how dense particulate systems respond to applied shear. In particular, we are interested in determining when these systems will possess linear velocity profiles and when they will develop highly localized velocity profiles in response to shear. In previous work on similar systems we showed that nonlinear velocity profiles form when the speed of the shearing boundary exceeds the speed of shear waves in the material. However, we find that nonlinear velocity profiles in these systems are unstable at very long times. The degree of nonlinearity slowly decreases in time; the velocity profiles become linear when the granular temperature and density profiles are uniform across the system at long times. We measure the time $t_l$ required for the velocity profiles to become linear and find that $t_l$ increases as a power-law with the speed of the shearing boundary and increases rapidly as the packing fraction approaches random close packing. We also performed simulations in which differences in the granular temperature across the system were maintained by vertically vibrating one of the boundaries during shear flow. We find that nonlinear velocity profiles form and are stable at long times if the difference in the granular temperature across the system exceeds a threshold value that is comparable to the glass transition temperature in an equilibrium system at the same average density. Finally, the sheared and vibrated systems form stable shear bands, or highly localized velocity profiles, when the applied shear stress is lowered below the yield stress of the static part of the system.Comment: 11 pages, 14 figure

MANAGER’S LEADERSHIP STYLES AND JOB PERFORMANCE OF COMPANY RANK AND FILE EMPLOYEES

In company management, several leadership styles are inherent and utilised by a manager or a leader. This study assessed the leadership styles of a manufacturing company manager and how the styles of leadership influence rank and file employees’ performance. In particular, it evaluated the manager’s leadership styles as affirmed by the rank and file employees, and how these leadership styles influence the performance of said employees from the viewpoint of work quality, work quantity, job innovativeness, customer service and team spirit. The study was carried out through a descriptive survey research design utilising a standardised survey questionnaire. Findings revealed that the branch Manager highly utilised transactional and transformational leadership styles in managing the manufacturing company. The Laissez-faire leadership style was only moderately utilised while the autocratic leadership was the least utilised style also at the moderate level. These utilised leadership styles manifested strong influence on the performance and productivity of rank and file employees of the manufacturing company under study. Accordingly, the employees exhibited outstanding performance towards the delivery of their works. It is concluded that managing the human capital of any company elicits full utilisation of good leadership styles supportive to the attainment of the company’s set goals and objectives and employees’ desired outputs and productivity. The company under study should continuously utilise and sustain the use of transactional and transformational leadership styles to keep employees’ productive performance, although there is always room for improvement. Other related studies may be pursued considering other variables or attributes of leadership styles not covered in this study. Article visualizations

Effect of CGM in the HbA1c and Coefficient of Variation of glucose in a pediatric sample

Aim of the study: Previous studies have found no significant improvements in glycated hemoglobin (HbA1c), while using Continuous Glucose Monitoring (CGM), with children and adolescents. The aim of this paper is to measure the change in HbA1c, and the Coefficient of Variation in glucose levels, when using CGM, once the effect of other relevant variables, such as gender, actual age, the years the patient has had diabetes, use of an insulin pump, the presence of autoimmune disease, other associated pathologies, and weekly hours of exercise, are controlled for. Methods: This is a retrospective study that uses a linear regression model. Data was collected from Type 1 Diabetes Mellitus (T1DM), children diagnosed between 2003 and 2017 in the Pediatric Unit for Diabetes in Zaragoza, Spain. We used a linear regression and the method of estimation is Ordinary Least Squares. Results: Results show that the use of CGM decreased the HbA1c value by 3.5% and the Coefficient of Variation by 14%. Conclusions: The implication of these results is that this device helped in the management of diabetes, although more research is needed to distinguish between different devices in terms of their efficacy

Effects of substituting rare-earth ion R by non-magnetic impurities in R2BaNiO5R_2BaNiO_5 - theory and numerical DMRG results

In this paper we study the effect of substituting R (rare-earth ion) by non-magnetic ions in the spin-1 chain material $R_2BaNiO_5$. Using a strong-coupling expansion and numerical density matrix renormalization group calculations, we show that spin-wave bound states are formed at the impurity site. Experimental consequences of the bound states are pointed out.Comment: 5 pages, 4 postscript figure

Approximate perturbed direct homotopy reduction method: infinite series reductions to two perturbed mKdV equations

An approximate perturbed direct homotopy reduction method is proposed and applied to two perturbed modified Korteweg-de Vries (mKdV) equations with fourth order dispersion and second order dissipation. The similarity reduction equations are derived to arbitrary orders. The method is valid not only for single soliton solution but also for the Painlev\'e II waves and periodic waves expressed by Jacobi elliptic functions for both fourth order dispersion and second order dissipation. The method is valid also for strong perturbations.Comment: 8 pages, 1 figur

Topological effects at short antiferromagnetic Heisenberg chains

The manifestations of topological effects in finite antiferromagnetic Heisenberg chains is examined by density matrix renormalization group technique in this paper. We find that difference between integer and half-integer spin chains shows up in ground state energy per site when length of spin chain is longer than $\sim\xi$, where $\xi\sim\exp(\pi S)$ is a spin-spin correlation length, for spin magnitude S up to 5/2. For open chains with spin magnitudes $S=5/2$ to S=5, we verify that end states with fractional spin quantum numbers $S'$ exist and are visible even when the chain length is much smaller than the correlation length $\xi$. The end states manifest themselves in the structure of the low energy excitation spectrum.Comment: 4 pages, 6 figure

Dynamic Evolution of a Quasi-Spherical General Polytropic Magnetofluid with Self-Gravity

In various astrophysical contexts, we analyze self-similar behaviours of magnetohydrodynamic (MHD) evolution of a quasi-spherical polytropic magnetized gas under self-gravity with the specific entropy conserved along streamlines. In particular, this MHD model analysis frees the scaling parameter $n$ in the conventional polytropic self-similar transformation from the constraint of $n+\gamma=2$ with $\gamma$ being the polytropic index and therefore substantially generalizes earlier analysis results on polytropic gas dynamics that has a constant specific entropy everywhere in space at all time. On the basis of the self-similar nonlinear MHD ordinary differential equations, we examine behaviours of the magnetosonic critical curves, the MHD shock conditions, and various asymptotic solutions. We then construct global semi-complete self-similar MHD solutions using a combination of analytical and numerical means and indicate plausible astrophysical applications of these magnetized flow solutions with or without MHD shocks.Comment: 21 pages, 7 figures, accepted for publication in APS

Multidimensional four-wave mixing signals detected by quantum squeezed light

Four-wave mixing (FWM) of optical fields has been extensively used in quantum information processing, sensing, and memories. It also forms a basis for nonlinear spectroscopies such as transient grating, stimulated Raman, and photon echo where phase matching is used to select desired components of the third-order response of matter. Here we report an experimental study of the two-dimensional quantum noise intensity difference spectra of a pair of squeezed beams generated by FWM in hot Rb vapor. The measurement reveals details of the χ(3) susceptibility dressed by the strong pump field which induces an AC Stark shift, with higher spectral resolution compared to classical measurements of probe and conjugate beam intensities. We demonstrate how quantum correlations of squeezed light can be utilized as a spectroscopic tool which unlike their classical counterparts are robust to external noise