Creation of magnetic spots at the neutron star surface

According to the partially screened gap scenario, an efficient electron-positron pair creation, a general precondition of radio-pulsar activity, relies on the existence of magnetic spots, i.e., local concentrations of strong and small scale magnetic field structures at the surface of neutron stars. They have a strong impact on the surface temperature, which is potentially observable. Here we reinforce the idea that such magnetic spots can be formed by extracting magnetic energy from the toroidal field that resides in deep crustal layers, via Hall drift. We study and discuss the magneto-thermal evolution of qualitatively different neutron star models and initial magnetic field configurations that lead to the creation of magnetic spots. We find that magnetic spots can be created on a timescale of $10^4$ years with magnetic field strengths $\gtrsim 5\times 10^{13}$ G, provided almost the whole magnetic energy is stored in its toroidal component, and that the conductivity in the inner crust is not too large. The lifetime of the magnetic spots is at least $\sim$one million of years, being longer if the initial field permeates both core and crust.Comment: Accepted by M.N.R.A.

Research on Cold Cathodes First Quarterly Report, 14 May - 14 Aug. 1965

Application of gallium phosphide crystals for hot-electron cold cathode research - life tests for silver-barium oxide phototubes - surface film, semiconductor, and vacuum requirement

Magnetothermal Evolution of Neutron Stars with Emphasis to Radio Pulsars

The magnetic and thermal evolution of neutron stars is a very complex process with many nonlinear interactions. For a decent understanding of neutron star physics, these evolutions cannot be considered isolated. A brief overview is presented, which describes the main magnetothermal interactions that determine the fate of both isolated neutron stars and accreting ones. Special attention is devoted to the interplay of thermal and magnetic evolution at the polar cap of radio pulsars. There, a strong meridional temperature gradient is maintained over the lifetime of radio pulsars. It may be strong enough to drive thermoelectric magnetic field creation which perpetuate a toroidal magnetic field around the polar cap rim. Such a local field component may amplify and curve the poloidal surface field at the cap, forming a strong and small scale magnetic field as required for the radio emission of pulsarsComment: Has appeared in Journal of Astrophysics and Astronomy special issue on 'Physics of Neutron Stars and Related Objects',celebrating the 75th birth-year of G. Srinivasa

Regional Patterns of Intangible Capital, Agglomeration Effects and Localised Spillovers in Germany

We use a large micro-dataset to assess the importance of intangible capital - organisation, R&D and ICT capital - for the economic performance of establishments and regions in Germany. In 2003 self-produced intangible capital accounted for more than one fifth of the total capital stock of estab-lishments. More than half of the intangible capital is R&D capital. This high proportion is mainly due to a relatively strong and research-intensive manufacturing sector in Germany. At the regional level, we find descriptive evidence for a positive relationship between intangible capital and the economic performance of regions. This is true both for the level of economic activities and for growth. The results of cross-sectional regressions for the years from 1999 to 2003 indicate that dou-bling the intangible capital intensity of establishments increases the average wage levels by one percent. Regarding the regional economic environment of establishments, we find that the substan-tial net advantages of agglomeration have more to do with broad knowledge and diversity than with regional clustering and specialisation. Separate regressions for the wage levels of non-intangible workers show very similar results. These workers can share the rents of the activities of intangible workers. Thus, intangible capital generates positive externalities not only at the regional level, but also at the level of establishments.Firm productivity, intangible capital, agglomeration, local spillovers

Corporate Donations to the Arts: Philanthropy or Advertising?

This paper is an attempt to provide evidence on two questions: Why do companies sponsor art events, and where exactly does the money go? We analyse data collected on the revenue structure of cultural institutions in Berlin and Hamburg. This data set not only tells us where the money goes, it also allows us to draw conclusions with respect to donors' motives. We regress sponsorships received on the number of visitors and other independent variables. The results are significantly different from those which one would expect if sponsoring were merely a form of advertising.

Micro-political aspects of mandate development and learning in local subsidiaries of multinational corporations

Beyond functional-structuralist approaches this paper sheds some light on micro political aspects of mandate development and learning processes in multinational corporations (MNC). As classical micro-political studies have shown, management behaviour and learning are not only constrained or enabled by certain structural and (national) cultural patterns, but have its own political agendas and are shaped by individual interests which leads to game playing, active or passive resistance and (re)negotiation of the 'rules of the game'. Based on the assumption that actors are neither the organs of given structures nor acting fully autonomous, the paper focuses on how subsidiary managers interpret and integrate individual, organisational as well as home and host country institutional factors into certain strategies of action. By discussing critical events in mini case studies on mandate development and learning in German subsidiaries in France we will highlight the interactive dynamics between key-actors micro-political strategies and particular institutional settings. Here we, firstly, discuss institutionalist approaches and investigate how different forms of home and host country embeddedness do influence the development of distinct managerial competences and decision making strategies at the subsidiary level. The paper refers then to the question how the overall strategy and multinational organisational design and policies relate to individual interests of key subsidiary actors. These can to higher or lower degrees be influenced by e.g. differences in nationalities, professional backgrounds as well as career stages, orientations and aspirations. By integrating these diverse relational layers, the paper will provide a more dynamic actor centred approach stressing both, the micro-political aspects and interactive construction of intra and intersubsidiary power relations, a key variable to explain mandate development and learning processes in MNCs. -- Über funktional-strukturalistische Ansätze hinausgehend, beschäftigt sich dieser Beitrag mit den mikropolitischen Aspekten von Mandatsentwicklungsprozessen in multinationalen Unternehmen. Im Zentrum der Betrachtung stehen die Strategien und Handlungsrationalitäten von Tochtergesellschaftsmanagern im Ausland. Anhand von drei Fallbeispielen zeigt der Beitrag wie Manager deutscher Auslandsgesellschaften in Frankreich individuelle, organisationale und institutionelle Faktoren (Heimat- und Gastlandeffekte) interpretieren und zu einer Handlungsstrategie verbinden. Ausgangspunkt ist dabei zunächst eine Diskussion relevanter Ansätze des Internationalen Managements und der international vergleichenden Organisationsforschung. Diese Ansätze werden um einen mikropolitischen Ansatz erweitert, der auf die spezifische Bedeutung von Nationalzugehörigkeit, professionellem Background und individueller Karriereorientierung bei Tochtergesellschaftsmanagern im Ausland abstellt.

Magnetic and spin evolution of neutron stars in close binaries

The evolution of neutron stars in close binary systems with a low-mass companion is considered assuming the magnetic field to be confined within the solid crust. We adopt the standard scenario of the evolution in a close binary system in accordance with which the neutron star passes throughout four evolutionary phases ("isolated pulsar" -- "propeller" -- accretion from the wind of a companion -- accretion due to Roche-lobe overflow). Calculations have been performed for a great variety of parameters characterizing the properties both of the neutron star and low-mass companion. We find that neutron stars with more or less standard magnetic field and spin period being processed in low-mass binaries can evolve to low-field rapidly rotating pulsars. Even if the main-sequence life of a companion is as long as $10^{10}$ yr, the neutron star can maintain a relatively strong magnetic field to the end of the accretion phase. The considered model can well account for the origin of millisecond pulsars.Comment: 18 pages + 10 figures, uses epsf.sty. Accepted by MNRA

Magnetic Field Decay in Neutron Stars. Analysis of General Relativistic Effects

An analysis of the role of general relativistic effects on the decay of neutron star's magnetic field is presented. At first, a generalized induction equation on an arbitrary static background geometry has been derived and, secondly, by a combination of analytical and numerical techniques, a comparison of the time scales for the decay of an initial dipole magnetic field in flat and curved spacetime is discussed. For the case of very simple neutron star models, rotation not accounted for and in the absence of cooling effects, we find that the inclusion of general relativistic effects result, on the average, in an enlargement of the decay time of the field in comparison to the flat spacetime case. Via numerical techniques we show that, the enlargement factor depends upon the dimensionless compactness ratio ${\epsilon}={2GM \over c^{2}R}$, and for ${\epsilon}$ in the range $(0.3~,~0.5)$, corresponding to compactness ratio of realistic neutron star models, this factor is between 1.2 to 1.3. The present analysis shows that general relativistic effects on the magnetic field decay ought to be examined more carefully than hitherto. A brief discussion of our findings on the impact of neutron stars physics is also presented.Comment: 35 pages, 4 figures, In press Phys. Rev. D1