Dynamical stability of nascent neutron stars

This thesis presents a study of the dynamical stability of nascent neutron stars resulting from the accretion induced collapse of rapidly rotating white dwarfs.

Chapter 2 and part of Chapter 3 study the equilibrium models for these neutron stars. They are constructed by assuming that the neutron stars have the same masses, angular momenta, and specific angular momentum distributions as the pre-collapse white dwarfs. If the pre-collapse white dwarf is rapidly rotating, the collapsed object will contain a high density central core of size about 20 km, surrounded by a massive accretion torus extending to hundreds of kilometers from the rotation axis. The ratio of the rotational kinetic energy to gravitational binding energy, β, of these neutron stars is all found to be less than 0.27.

Chapter 3 studies the dynamical stability of these neutron stars by numerically evolving the linearized hydrodynamical equations. A dynamical bar-mode instability is observed when the β of the star is greater than the critical value β_d ≈ 0.25. It is expected that the unstable mode will persist until a substantial amount of angular momentum is carried away by gravitational radiation. The detectability of these sources is studied and it is estimated that LIGO II is unlikely to detect them unless the event rate is greater than 10^-6/year/galaxy.

All the calculations on the structure and stability of the neutron stars in Chapters 2 and 3 are carried out using Newtonian hydrodynamics and gravity. Chapter 4 studies the relativistic effects on the structure of these neutron stars. New techniques are developed and used to construct neutron star models to the first post-Newtonian (1PN) order. The structures of the 1PN models are qualitatively similar to the corresponding Newtonian models, but the values of β are somewhat smaller. The maximum β for these 1PN neutron stars is found to be 0.24, which is 8% smaller than the Newtonian result (0.26). However, relativistic effects will also change the critical value β_d. A detailed post-Newtonian stability analysis has yet to be carried out to study the relativistic effects on the dynamical stability of these neutron stars.

Entrepreneurship in the University of the Basque Country (UPV/EHU)

Currently entrepreneurship is a basic pillar in the socioeconomic area of any country since it contributes to attain the government objectives of job creation and boost of dynamism and competitiveness of the business network. These aspects are even more crucial nowadays due to the global economic crisis. This paper attempts to provide some new insights about the scientific field entrepreneurship in the Basque Country analyzing some aspects related to the entrepreneurial activity, the profile of the entrepreneur and the characteristics of the entrepreneurial businesses. It also aims to provide empirical evidence that proves the good features of the spin-offs and TBF groups as job creators, technology transferors to the society and important actors in the growth and development of the economies for both the business network and its surrounding society. To this aim, a descriptive study has been performed of the firms belonging to the Zitek Program of Bizkaia Campus of the University of the Basque Country (UPV/EHU).

Is it possible to measure social entrepreneurship in firms?

[EN] This study defines and proposes a measurement scale for social entrepreneurship (SE) in its broadest sense. The broad definition of SE covers for-profit firms that use social aims as a core component of their strategy. By pursuing social aims, these firms can boost the value of their products or services for consumers or exploit new business areas. Under this broad definition of SE, profit-seeking and the pursuit of social aims converge, thereby revealing a form of SE that has received little attention in either theoretical or empirical research. To fill this research gap, the present study proposes a measurement scale to measure broad SE in firms. The process used to build the scale draws upon research by Churchill (1979) and DeVellis (1991) and combines the Delphi technique, a pre-test questionnaire and structural equation modelling. The main aim of this research is to develop a scale capable of measuring broad SE in firms. The theoretical basis for the scale is supported by an empirical study in the hotel sector. The scale provides a valid, reliable instrument for measuring broad SE in firms. The scale meets all sociometric properties required of measurement scales in the social sciences, namely dimensionality, reliability and validity.

Policy entrepreneurship in the development of public sector strategy: the case of London health reform

The development of health policy is recognized as complex; however, there has been little development of the role of agency in this process. Kingdon developed the concept of policy entrepreneur (PE) within his ‘windows’ model. He argued inter-related ‘policy streams' must coincide for important issues to become addressed. The conjoining of these streams may be aided by a policy entrepreneur. We contribute by clarifying the role of the policy entrepreneur and highlighting the translational processes of key actors in creating and aligning policy windows. We analyse the work in London of Professor Sir Ara Darzi as a policy entrepreneur. An important aspect of Darzi's approach was to align a number of important institutional networks to conjoin related problems. Our findings highlight how a policy entrepreneur not only opens policy windows but also yokes together a network to make policy agendas happen. Our contribution reveals the role of clinical leadership in health reform.

Evolving corporate entrepreneurship strategy: Technology incubation at Philips

Established firms tend to pursue incremental innovation by modifying and refining their existing products and processes rather than developing radical innovations. In the face of resistance to change and incumbent inertia, which prevent the generation of novelty, established firms have turned towards corporate entrepreneurship as a means of exploiting knowledge accumulated within its own boundaries and exploring external markets. This paper focuses on one mode of corporate entrepreneurship, corporate incubation, informed by a study of a Technology Incubator at Philips. An account of the history of the incubator traces its progress from its inception in 2002-2006 when further incubators were formed, building on this experience and focusing on lifestyle and healthcare technologies. We identify ways in which the Philips incubator represents an alternative selection environment that effectively simulated the venture capitalist model of entrepreneurial innovation. © 2009 Blackwell Publishing Ltd.