8,371 research outputs found

    The multi-wavelength polarization of Cygnus X-1

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    Polarization measurements of the microquasar Cygnus X-1 exist at gamma-ray, X-ray, UV, optical and radio frequencies. The gamma-ray emission has been shown to be highly linearly polarized. Here, we present new infrared polarimetric data of Cygnus X-1 taken with the 10.4-m Gran Telescopio Canarias and the 4.2-m William Herschel Telescope. We show that the broadband, radio to gamma-ray flux spectrum and polarization spectrum in the hard state are largely consistent with a simple phenomenological model of a strongly polarized synchrotron jet, an unpolarized Comptonized corona and a moderately polarized interstellar dust component. In this model, the origin of the gamma-ray, X-ray and some of the infrared polarization is the optically thin synchrotron power law from the inner regions of the jet. The model requires the magnetic field in this region to be highly ordered and perpendicular to the axis of the resolved radio jet. This differs to studies of some other X-ray binaries, in which the magnetic field is turbulent, variable and aligned with the jet axis. The model is able to explain the approximate polarization strength and position angle at all wavelengths including the detected X-ray (3 - 5 keV) polarization, except the observed position angle of the gamma-ray polarization, which differs to the model by ~ 60 degrees. Past numerical modelling has shown that a curved synchrotron spectrum can produce a shift in position angle by ~ 60 degrees, which may account for this.Comment: Accepted in MNRA

    Capital Markets and Foreign Ownership Restrictions: An Empirical Analysis of Emerging Stock Markets

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    In the 1990s, the hot issue in international finance was the growing interest of portfolio managers in the emerging stock markets. The interest in the emerging markets gained rapid attention, which is evident from the global trends, towards the opening up of economies and financial markets, free capital flow and the privatisation of financial institutions. Earlier the emerging markets were isolated due to several factors that had posed serious problems for international investors. These markets lacked the depth, regulatory framework, and structural safeguards that had characterised the equity markets in the developed world. Capital markets are called integrated, if assets with perfectly correlated rates of returns have the same price regardless of the location in which they are traded. Alternatively, capital market are called segmented, if financial assets traded in different markets “with identical risk characteristics” have different returns due to different investment restrictions.1 Segmentation may be due to individuals’ attitudes, government restrictions over capital movements or irrationality. In the past twenty-five years, modern finance theory has proved to be a major development in finance, which comprises of portfolio theory, capital market theory and efficient market theory. These modern developments can be traced back to the work of Markowitz (1959); Sharpe (1964); Solnik (1974) etc., which assumes that security prices fully reflect all publicly available information. Due to this information, potential investors can gain benefits through international diversification. The major attraction of forming international portfolios lies in the potential for risk reduction through diversification of unsystematic risk.

    Economic Growth and Income Inequality Relationship: Role of Credit Market Imperfection

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    This paper examines the empirical relationship between economic growth and income inequality both at aggregate and regional level using more comparable data set for 69 developing countries over the period 1965-2003. The study identifies credit market imperfection in low-income developing countries as the likely reason for a strong negative relationship between income inequality and economic growth. While in short run the relationship between growth and income inequality might be positive but over time more income inequalities reduces economic growth. Moreover, this paper finds evidence that more physical and human capital investment, openness to trade and higher government spending have statistically significant impact on enhancing economic growth and reducing inequality.Economic Growth, Income Inequality, Poverty, Credit Market Imperfection, Trade Openness

    Polarized synchrotron emission in quiescent black hole X-ray transients

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    We present near-infrared polarimetric observations of the black hole X-ray binaries Swift J1357.2-0933 and A0620-00. In both sources, recent studies have demonstrated the presence of variable infrared synchrotron emission in quiescence, most likely from weak compact jets. For Swift J1357.2-0933 we find that the synchrotron emission is polarized at a level of 8.0 +- 2.5 per cent (a 3.2 sigma detection of intrinsic polarization). The mean magnitude and rms variability of the flux (fractional rms of 19-24 per cent in K_s-band) agree with previous observations. These properties imply a continuously launched (stable on long timescales), highly variable (on short timescales) jet in the Swift J1357.2-0933 system in quiescence, which has a moderately tangled magnetic field close to the base of the jet. We find that for A0620-00, there are likely to be three components to the optical-infrared polarization; interstellar dust along the line of sight, scattering within the system, and an additional source that changes the polarization position angle in the reddest (H and K_s) wave-bands. We interpret this as a stronger contribution of synchrotron emission, and by subtracting the line-of-sight polarization, we measure an excess of ~ 1.25 +- 0.28 per cent polarization and a position angle of the magnetic field vector that is consistent with being parallel with the axis of the resolved radio jet. These results imply that weak jets in low luminosity accreting systems have magnetic fields which possess similarly tangled fields compared to the more luminous, hard state jets in X-ray binaries.Comment: Accepted to MNRA

    Role of Quality Management in Pharmaceutical Development: Evidence from Islamabad and Lahore

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    The aim of this paper is to investigate the employee’s perceptions of the impact, of Total Quality Management (TQM), on their roles within the organization and how they perceived the effectiveness of the quality processes in Pakistan Pharmaceutical industry. The universe of this study was the employees of Pharmaceutical industry in Islamabad and Lahore. For this purpose survey method was used by using questionnaire as a tool for data collection. The results have shown that Employee Training and Development, Employee Performance, Quality Process and Team Work are significant factors with the Total Quality Management and correlated with each others. The result shows the application of TQM principles addresses some of the key challenges facing the organization. The study was faced by certain limitations and included time constraints and resources constraints which limited this research to only Islamabad and Lahore offices, of the Pharmaceutical companies. The present study found support that pharmaceutical companies faced the same difficulties with TQM implementations as experienced in other industries. These include achieving a culture of continuous improvement, overcoming a lack of trust and understanding the TQM process itself, and what they were, as a company, trying to achieve. These problems are not new and many companies have difficulties in implementing TQM. Pharmaceutical companies also followed the path of achieving a quality certification; namely, ISO 9000 accreditation, in the pursuit of excellence.Quality Management; pharmaceutical Development; Pakistan; Employee’s Perceptions
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