X-ray Statistical Properties of the Central Cool Component in Clusters of Galaxies

Central cool gas component that is often observed from a well-relaxed cluster system has long been interpreted as a consequence of ``Cooling Flow'' (CF), radiative cooling followed by inflow of Intra-Cluster Medium (ICM). However, recent XMM-Newton spectroscopy has shown no signatures of cooler gas phases below certain temperatures in typical CF clusters (A1795, Tamura et al. 2001; A1835, Peterson et al. 2001). This contradicts the conventional CF model or at least requires a major revision of the model. In order to investigate statistical properties of the central cool component, we performed systematic analysis of ASCA data on 85 clusters. We found that 1) temperature of the central cool component strongly depends on the temperature of the main ICM, 2) the cool component is selectively found around a brightest cluster galaxy (BCG) that coincide with the X-ray peak position, and 3) the luminosity-temperature (L-T) relation of the cool component shows nice agreement with the L-T relation of the main ICM. Together with the previous observational fact that, in some of the ``CF'' clusters, the total gravitating mass is clustering in two distinct spatial scales, a main cluster component and a second small-scale system, we conclude that the central cool component is associated with the second small-scale self-gravitating system that is immersed in the host cluster, and the cool component temperature reflects the gravitational potential depth.Comment: Proceedings of "Tracing Cosmic Evolution with Clusters of Galaxies", Sesto Pusteria, Bolzano, Italy, July 3-6, 200

X-ray Diagnostics of Thermal Conditions of the Hot Plasmas in the Centaurus Cluster

X-ray data of the Centaurus cluster, obtained with {\it XMM-Newton} for 45 ksec, were analyzed. Deprojected EPIC spectra from concentric thin shell regions were reproduced equally well by a single-phase plasma emission model, or by a two-phase model developed by {\it ASCA}, both incorporating cool (1.7--2.0 keV) and hot ($\sim 4$ keV) plasma temperatures. However, EPIC spectra with higher statistics, accumulated over 3-dimentional thick shell regions, were reproduced better by the two-phase model than by the singe-phase one. Therefore, hot and cool plasma phases are inferred to co-exist in the cluster core region within $\sim 70$ kpc. The iron and silicon abundances of the plasma were reconfirmed to increase significantly towards the center, while that of oxygen was consistent with being radially constant. The implied non-solar abundance ratios explains away the previously reported excess X-ray absorption from the central region. Although an additional cool ($\sim 0.7$ keV) emission was detected within $\sim 20$ kpc of the center, the RGS data gave tight upper limits on any emission with a tempeartures below $\sim 0.5$ keV. These results are compiled into a magnetosphere model, which interprets the cool phase as confined within closed magnetic loops anchored to the cD galaxy. When combined with so-called Rosner-Tucker-Vaiana mechanism which applies to solar coronae, this model can potentially explain basic properties of the cool phase, including its temperature and thermal stability.Comment: 53 pages, 11 figures, accepted for publication in Astrophysical Journa

On inverses of Hessenberg matrices

AbstractThe lower half of the inverse of a lower Hessenberg matrix is shown to have a simple structure. The result is applied to find an algorithm for finding the inverse of a tridiagonal matrix. With minor modifications, the technique applies to block Hessenberg matrices

In Place of Liberation: Failure of Labour Politics in Britain, 1964-79

The crisis of the Fordist-Keynesian mode of production in the 1970s throughout the advanced capitalist world precipitated an acute political contestation over the mode of production itself. The dramatic ascendency of the neoliberal mode of regulation was a paradigm shift of rare occurrence whose significance in the history of capitalism cannot be overstated. This thesis seeks to contribute to the understanding of neoliberalism\u27s rise and the failure of alternative possibilities, focusing upon the British case where the stagflationary crisis was particularly acute in the \u2770s and the change in the mode of production was particularly drastic. This thesis focuses upon the actions of the Labour Party and the trade unions that constitute the primary and most influential oppositional forces against the capital\u27s power. In Britain, while the Labour Party was in government for the pivotal years of 1974-79 and the trade unions gained an unprecedented level of strength in the 1970s, they failed to develop a system alternative to neoliberalism. Instead, the Labour Government started to take a reluctant, small yet unmistakable step towards neoliberalism, and neither the unions\u27 cooperation with the incomes policy nor their refusal to continue compliance (most spectacularly manifested in the Winter of Discontents) led to the successful articulation (let alone implementation) of a non-neoliberal post-Fordist regime. The failure of the historic champions of the workers and the welfare state on the centre-left was a crucial factor in enabling the neoliberal retrenchment. This thesis locates a significant reason for labour\u27s failure in the ideas held by them. Integrating the ideational analysis with historical institutionalism in the dialectic of ideas and interests, it is argued that the actions of the Labour Party and the unions were shaped by the ideational path dependence their continued adherence to the Fordist ideas prevented the possibility to envision alternative conceptions of political economy based on emancipation of the workers. The Fordist ideas include productivism and masculinism the notions that privilege the higher levels of material production and the male breadwinner model. As such, they were unable to conceptualize their interests as anything except for the increase in their levels of private consumption. Productivism, masculinism and (neoliberal) capitalism reinforce each other. Productivism is a cultural condition of capitalism that affirms and legitimizes its fundamental law of motion that never ceases to exhort accumulate, accumulate! by prioritizing what capitalism deems as productive; capitalism structurally functions to realize productivist goals. Masculinism aids capitalism and productivism by providing an ideology that glorifies the system of reproduction of labour power and socially-necessary care labour that incurs the cheapest cost and least threat to capital (women\u27s unpaid labour in families), and capitalism buttresses masculinism by preventing the rise of de-familiarizing welfare state. Productivism is connected to masculinism, not only in a discursive, cultural sense; productivism serves to lengthen women\u27s working hours and disregards the politics of working time, and masculinism devalues the economic activities considered unproductive by productivists

Supervillin slows cell spreading by facilitating myosin II activation at the cell periphery

During cell migration, myosin II modulates adhesion, cell protrusion and actin organization at the leading edge. We show that an F-actin- and membrane-associated scaffolding protein, called supervillin (SV, p205), binds directly to the subfragment 2 domains of nonmuscle myosin IIA and myosin IIB and to the N-terminus of the long form of myosin light chain kinase (L-MLCK). SV inhibits cell spreading via an MLCK- and myosin II-dependent mechanism. Overexpression of SV reduces the rate of cell spreading, and RNAi-mediated knockdown of endogenous SV increases it. Endogenous and EGFP-tagged SV colocalize with, and enhance the formation of, cortical bundles of F-actin and activated myosin II during early cell spreading. The effects of SV are reversed by inhibition of myosin heavy chain (MHC) ATPase (blebbistatin), MLCK (ML-7) or MEK (U0126), but not by inhibiting Rho-kinase with Y-27632. Flag-tagged L-MLCK co-localizes in cortical bundles with EGFP-SV, and kinase-dead L-MLCK disorganizes these bundles. The L-MLCK- and myosin-binding site in SV, SV1-171, rearranges and co-localizes with mono- and di-phosphorylated myosin light chain and with L-MLCK, but not with the short form of MLCK (S-MLCK) or with myosin phosphatase. Thus, the membrane protein SV apparently contributes to myosin II assembly during cell spreading by modulating myosin II regulation by L-MLCK

Sustaining Occupational Information for Career Choice and Development in Students of Technical Colleges in Enugu State, Nigeria

This study takes on the issue of sustaining occupational information for career choice and development in students of technical colleges in Enugu State, Nigeria. The method adopted for this study was the survey design and the population included were all final year students of the three government technical colleges in Enugu State of Nigeria. The technical colleges were sampled as follows: Government Technical College, Enugu (156 students); Government Technical College, Nsukka (148 students); and Government Technical College, Akpugoeze (132 students). Four research questions were raised for the study. A total of 32 structured questionnaire were developed to elicit information from the respondents. The data gathered were analysed using mean and standard deviation. The findings of the study revealed that occupational information helps students make better career choice through exposure and knowledge gained on world of work. Environment, personality of the students, qualities of occupation and opportunities available, influence career choice of technical college students. The career resource library, programmes, seminars, workshops and vocational college counsellor are sources of career information. It is recommended that students should find sources on career information especially from online and vocational college counsellors before making any career choice or occupations to match their personalities and abilitie