453 research outputs found
Inducing the cosmological constant from five-dimensional Weyl space
We investigate the possibility of inducing the cosmological constant from
extra dimensions by embedding our four-dimensional Riemannian space-time into a
five-dimensional Weyl integrable space. Following approach of the induced
matter theory we show that when we go down from five to four dimensions, the
Weyl field may contribute both to the induced energy-tensor as well as to the
cosmological constant, or more generally, it may generate a time-dependent
cosmological parameter. As an application, we construct a simple cosmological
model which has some interesting properties.Comment: 7 page
The Pioneer Anomaly and a Machian Universe
We discuss astronomical and astrophysical evidence, which we relate to the
principle of zero-total energy of the Universe, that imply several relations
among the mass M, the radius R and the angular momentum L of a "large" sphere
representing a Machian Universe. By calculating the angular speed, we find a
peculiar centripetal acceleration for the Universe. This is an ubiquituous
property that relates one observer to any observable. It turns out that this is
exactly the anomalous acceleration observed on the Pioneers spaceships. We have
thus, shown that this anomaly is to be considered a property of the Machian
Universe. We discuss several possible arguments against our proposal.Comment: 6 pages including front page. Publishe
An Embedding for General Relativity and its Implications for New Physics
We show that any solution of the 4D Einstein equations of general relativity
in vacuum with a cosmological constant may be embedded in a solution of the 5D
Ricci-flat equations with an effective 4D cosmological "constant" that is a
specific function of the extra coordinate. For unified theories of the forces
in higher dimensions, this has major physical implications
Hawking Temperature in Taub-NUT (A)dS spaces via the Generalized Uncertainty Principle
Using the extended forms of the Heisenberg uncertainty principle from string
theory and the quantum gravity theory, we drived Hawking temperature of a
Taub-Nut-(A)dS black hole. In spite of their distinctive natures such as
asymptotically locally flat and breakdown of the area theorem of the horizon
for the black holes, we show that the corrections to Hawking temperature by the
generalized versions of the the Heisenberg uncertainty principle increases like
the Schwarzschild-(A)dS black hole and give the reason why the Taub-Nut-(A)dS
metric may have AdS/CFT dual picture.Comment: version published in General Relativity and Gravitatio
Higher spin quaternion waves in the Klein-Gordon theory
Electromagnetic interactions are discussed in the context of the Klein-Gordon
fermion equation. The Mott scattering amplitude is derived in leading order
perturbation theory and the result of the Dirac theory is reproduced except for
an overall factor of sixteen. The discrepancy is not resolved as the study
points into another direction. The vertex structures involved in the scattering
calculations indicate the relevance of a modified Klein-Gordon equation, which
takes into account the number of polarization states of the considered quantum
field. In this equation the d'Alembertian is acting on quaternion-like plane
waves, which can be generalized to representations of arbitrary spin. The
method provides the same relation between mass and spin that has been found
previously by Majorana, Gelfand, and Yaglom in infinite spin theories
Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c
We have searched for the K+ to pi+ gamma gamma decay in the kinematic region
with pi+ momentum close to the end point. No events were observed, and the 90%
confidence-level upper limit on the partial branching ratio was obtained, B(K+
to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral
perturbation theory including next-to-leading order ``unitarity'' corrections.
The same data were used to determine an upper limit on the K+ to pi+ gamma
branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for
publication in Physics Letters
Enhancing the Social Capital of Learning Communities by Using an Ad Hoc Transient Communities Service
Fetter, S., Berlanga, A. J., & Sloep, P. B. (2009). Enhancing the Social Capital of Learning Communities by Using an Ad Hoc Transient Communities Service. In M. Spaniol, Q. Li, R. Klamma & R. W. H. Lau (Eds.), Proceedings of the 8th International Conference Advances in Web-based Learning - ICWL 2009 (pp. 150-157). August, 19-21, 2009, Aachen, Germany. Lecture Notes in Computer Science 5686; Berlin, Heidelberg: Springer-Verlag.In online learning, communities can help to enhance learning. However, because of the dynamic nature of communities, attaining and sustaining these communities can be difficult. One aspect that has an influence on, and is influenced by these dynamics is the social capital of a community. Features of social capital are the social network structure, the sense of belonging and, the support received and provided. It is hypothesized that these features can be improved by using Ad Hoc Transient Communities (AHTCs). Through an AHTC learners are brought together for a specific, learning-related goal (‘ad hoc’) and for only a limited amount of time (‘transience’). To test whether the use of AHTCs has a positive influence on the social capital, a learner support service which enables the use of AHTCs is proposed. Furthermore, requirements, pre-requisites, and future research are discussed.The work on this publication has been sponsored by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org
Supersymmetrization of Quaternion Dirac Equation for Generalized Fields of Dyons
The quaternion Dirac equation in presence of generalized electromagnetic
field has been discussed in terms of two gauge potentials of dyons.
Accordingly, the supersymmetry has been established consistently and thereafter
the one, two and component Dirac Spinors of generalized quaternion Dirac
equation of dyons for various energy and spin values are obtained for different
cases in order to understand the duality invariance between the electric and
magnetic constituents of dyons.Comment: Key words: Supersymmetry, quaternion, Dirac equation, dyons PACS No.:
11.30.Pb, 14.80.Ly, 03.65.G
Teams between Neo-Taylorism and Anti-Taylorism
The concept of teamworking is the product of two distinct
developments. One: a neo-
Tayloristic form of organization of work, of which Toyota has shown
that it can be very profitable, was
packaged and reframed to make it acceptable to the Western public.
Two: anti-Tayloristic ways of
organizing work, inspired by ideals of organizational democracy,
were relabeled to make these
acceptable to profit-oriented managers.
Drawing on empirical research in Scandinavia, Germany, The
Netherlands and the UK, as
well as on published case studies of Japanese companies, the paper
develops a neo-Tayloristic and an
anti-Tayloristic model of teamworking.
Key concerns in the teamworking literature are intensification of
work and the use of shop
floor autonomy as a cosmetic or manipulative device. Indeed, all the
features of neo-Tayloristic
teamworking are geared towards the intensification of work. However,
one of the intensification
mechanisms, the removal of Tayloristic rigidities in the division of
labor, applies to anti-Tayloristic
teamworking as well. This poses a dilemma for employee
representatives. In terms of autonomy, on the
other hand, the difference between neo-Tayloristic and
anti-Tayloristic teamworking is real.
In anti-Tayloristic teamworking, there is no supervisor inside the
team. The function of
spokesperson rotates. All team members can participate in
decision-making. Standardization is not
relentlessly pursued; management accepts some measure of worker
control. There is a tendency to
alleviate technical discipline, e.g. to find alternatives for the
assembly line. Buffers are used.
Remuneration is based on proven skill level; there are no group
bonuses.
In contrast, in neo-Tayloristic teamworking, a permanent supervisor
is present in the team as
team leader. At most, only the team leader can participate in
decision-making. Standardization is
relentlessly pursued. Management prerogatives are nearly unlimited.
Job designers treat technical
discipline, e.g. short-cycled work on the assembly line, as
unproblematic. There are no buffers. A
substantial part of wages consists of individual bonuses based on
assessments by supervisors on how
deeply workers cooperate in the system. Group bonuses are also
given.
The instability and vulnerability of anti-Tayloristic teamworking
imply that it can only
develop and flourish when managers and employee representatives put
determined effort into it. The
opportunity structure for this contains both economic and political
elements. In mass production, the
economic success of Toyota, through skillful mediation by management
gurus, makes the opportunity
structure for anti-Tayloristic teamworking relatively unfavorable
Aldose Reductase Genotypes and Cardiorenal Complications: An 8-year prospective analysis of 1,074 type 2 diabetic patients
OBJECTIVE—We report the independent risk association of type 2 diabetic nephropathy with the z−2 allele of the 5′-(CA)n microsatellite and C-106T promoter polymorphisms of the aldose reductase gene (ALR2) using a case-control design. In this expanded cohort, we examined their predictive roles on new onset of cardiorenal complications using a prospective design
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