17,140 research outputs found
The Null Condition and Global Existence for Nonlinear Wave Equations on Slowly Rotating Kerr Spacetimes
We study a semilinear equation with derivatives satisfying a null condition
on slowly rotating Kerr spacetimes. We prove that given sufficiently small
initial data, the solution exists globally in time and decays with a
quantitative rate to the trivial solution. The proof uses the robust vector
field method. It makes use of the decay properties of the linear wave equation
on Kerr spacetime, in particular the improved decay rates in the region
Removing the Digital Divide for Senior Web Users
It is hard for the elderly to use the internet to find the resource they want. Usually help is needed for them to complete the task on the technology things. The main reason for this project is to research ideas on encourage senior people to make use of the web to locate helps they want, such as finding volunteers and professional helps. The scope of this project is to develop a new way of web access and content presentation methodologies that let senior people getting help from volunteers and various service providers more easily that incorporates social networking technology e.g. Facebook. By incorporating the social network web site like Facebook into the web application, senior people will be able to find volunteering help or other related service providers through social networking. Volunteers will show up in Google map in search results for senior to easily locate helps. Senior people can also search for self help videos tutorials through the web application search engine. A mobile version of the senior user application will also be developed for easy access on the road. Other features that benefit senior users includes voice input, control / content posting and collaborative social networking where a sponsors would sponsor a help task volunteer undertake
Examining CP Symmetry in Strange Baryon Decays
Non-conservation of CP symmetry can manisfest itself in non-leptonic hyperon
decays as a difference in the decay parameter between the strange-baryon decay
and its charge conjugate. By comparing the decay distribution in the
helicity frame for the decay sequence , with that of decay, E756 at Fermilab did not
observe any CP-odd effect at the level. The status of a follow-up
experiment, HyperCP (FNAL E871), to search for CP violation in charged
decay with a sensitivity of is also presented.Comment: 9 pages, 4 figures, invited talk presented at the Third International
Conference on B Physics and CP Violation, 3-7 Dec 1999, Taipei, Taiwa
The EU as a Global Actor in a Multipolar World and Multilateral 2.0 Environment. Egmont Paper No. 36, March 2010
This paper discusses a number of long-term global trends that are likely to affect the ambition of the EU to be a global actor. Being or becoming a global power is indeed not only determined by an internal and voluntary policy of that actor. It also depends on a number of external forces. The first part of this paper will present two ongoing transformations of the world that together are weakening the position of the EU as an aspiring global power. The first trend is a shift in economic gravity from the East to the West. The second trend is a demographic decline in Europe. Both trends make it increasingly difficult for the EU to be a global power. But at the same time one can also identify a number of developments with regard to multilateralism that bear in them opportunities for the EU to increase its influence as a global actor. The second part of this paper focuses on two such trends, the shift to multipolarity and the changes in the multilateral architecture. As for the latter, this paper introduces the notion of 'multilateralism 2.0.' as a metaphor to grasp these changes
Local Propagation of Impulsive Gravitational Waves
In this paper, we initiate the rigorous mathematical study of the problem of
impulsive gravitational spacetime waves. We construct such spacetimes as
solutions to the characteristic initial value problem of the Einstein vacuum
equations with a data curvature delta singularity. We show that in the
resulting spacetime, the delta singularity propagates along a characteristic
hypersurface, while away from that hypersurface the spacetime remains smooth.
Unlike the known explicit examples of impulsive gravitational spacetimes, this
work in particular provides the first construction of an impulsive
gravitational wave of compact extent and does not require any symmetry
assumptions. The arguments in the present paper also extend to the problem of
existence and uniqueness of solutions to a larger class of non-regular
characteristic data
Angle Combinations in Spherical Tilings by Congruent Pentagons
We develop a systematic method for computing the angle combinations in
spherical tilings by angle congruent pentagons, and study whether such
combinations can be realized by actual angle or geometrically congruent
tilings. We get major families of angle or geometrically congruent tilings
related to the platonic solids.Comment: 58 pages, 5 figure
Spirituality and business: An interdisciplinary overview
The paper gives an interdisciplinary overview of the emerging field of spirituality and business. It uses insights from business ethics, theology, neuroscience, psychology, gender studies, and philosophy to economics, management, organizational science, and banking and refers to different religious convictions including Christianity, Judaism, Islam, Hinduism, Buddhism, Confucianism, the Baha'i faith, and the North-American aboriginal worldview. The authors argue that the materialistic management paradigm has failed. They explore new values for post-materialistic management: frugality, deep ecology, trust, reciprocity, responsibility for future generations, and authenticity. Within this framework profit and growth are no longer ultimate aims but elements in a wider set of values. Similarly, cost-benefit calculations are no longer the essence of management but are part of a broader concept of wisdom in leadership. Spirit-driven businesses require intrinsic motivation for serving the common good and using holistic evaluation schemes for measuring success. The Palgrave Handbook of Business and Spirituality, edited by the authors, is a response to developments that simultaneously challenge the âbusiness as usualâ mindset
Trapped surfaces in vacuum arising dynamically from mild incoming radiation
In this paper, we study the "minimal requirement" on the incoming radiation
that guarantees a trapped surface to form in vacuum. First, we extend the
region of existence in Christodoulou's theorem on the formation of trapped
surfaces and consequently show that the lower bound required to form a trapped
surface can be relaxed. Second, we demonstrate that trapped surfaces form
dynamically from a class of initial data which are large merely in a
scaling-critical norm. This result is motivated in part by the scaling in
Christodoulou's formation of trapped surfaces theorem for the Einstein-scalar
field system in spherical symmetry
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