34,075 research outputs found
The Fourth Generation t-prime in Extensions of the Standard Model
We study the effects of a fourth generation t' quark in various extensions of
the standard model. In the Randall-Sundrum model, the decay t'--> t Z has a
large branching ratio that could be detected at the Large Hadron Collider
(LHC). We also look at the two-Higgs doublet models I, II and III, and note
that, in the latter, the branching ratio of t' --> t H, where H is a Higgs
scalar or pseudoscalar, is huge and we discuss detection at the LHC. A few
comments about the minimal supersymmetric standard model are also included.Comment: 4 pages, 2 figures. Version to be published in Phys. Rev.
Optimized mobile thin clients through a MPEG-4 BiFS semantic remote display framework
According to the thin client computing principle, the user interface is physically separated from the application logic. In practice only a viewer component is executed on the client device, rendering the display updates received from the distant application server and capturing the user interaction. Existing remote display frameworks are not optimized to encode the complex scenes of modern applications, which are composed of objects with very diverse graphical characteristics. In order to tackle this challenge, we propose to transfer to the client, in addition to the binary encoded objects, semantic information about the characteristics of each object. Through this semantic knowledge, the client is enabled to react autonomously on user input and does not have to wait for the display update from the server. Resulting in a reduction of the interaction latency and a mitigation of the bursty remote display traffic pattern, the presented framework is of particular interest in a wireless context, where the bandwidth is limited and expensive. In this paper, we describe a generic architecture of a semantic remote display framework. Furthermore, we have developed a prototype using the MPEG-4 Binary Format for Scenes to convey the semantic information to the client. We experimentally compare the bandwidth consumption of MPEG-4 BiFS with existing, non-semantic, remote display frameworks. In a text editing scenario, we realize an average reduction of 23% of the data peaks that are observed in remote display protocol traffic
Marshall-Peierls sign rule for excited states of the frustrated J1-J2 Heisenberg antiferromagnet
We present analytical and numerical calculations for some exited states of
the frustrated J1-J2 spin-1/2 Heisenberg model for linear chains and square
lattices. We consider the lowest eigenstates in the subspaces determined by the
eigenvalue M of the spin operator S_total^z. Because of the reduced number of
Ising basis states in the subspaces with higher M we are able to diagonalize
systems with up to N=144 spins. We find evidence that the Marshall-Peierls sign
rule survives for a relatively large frustration parameter J2.Comment: 7 pages, LaTeX, 4 eps figures, to appear in Physica
Age-related deficits in skeletal muscle recovery following disuse are associated with neuromuscular junction instability and ER stress, not impaired protein synthesis.
Age-related loss of muscle mass and strength can be accelerated by impaired recovery of muscle mass following a transient atrophic stimulus. The aim of this study was to identify the mechanisms underlying the attenuated recovery of muscle mass and strength in old rats following disuse-induced atrophy. Adult (9 month) and old (29 month) male F344BN rats underwent hindlimb unloading (HU) followed by reloading. HU induced significant atrophy of the hindlimb muscles in both adult (17-38%) and old (8-29%) rats, but only the adult rats exhibited full recovery of muscle mass and strength upon reloading. Upon reloading, total RNA and protein synthesis increased to a similar extent in adult and old muscles. At baseline and upon reloading, however, proteasome-mediated degradation was suppressed leading to an accumulation of ubiquitin-tagged proteins and p62. Further, ER stress, as measured by CHOP expression, was elevated at baseline and upon reloading in old rats. Analysis of mRNA expression revealed increases in HDAC4, Runx1, myogenin, Gadd45a, and the AChRs in old rats, suggesting neuromuscular junction instability/denervation. Collectively, our data suggests that with aging, impaired neuromuscular transmission and deficits in the proteostasis network contribute to defects in muscle fiber remodeling and functional recovery of muscle mass and strength
An Atlas of Predicted Exotic Gravitational Lenses
Wide-field optical imaging surveys will contain tens of thousands of new
strong gravitational lenses. Some of these will have new and unusual image
configurations, and so will enable new applications: for example, systems with
high image multiplicity will allow more detailed study of galaxy and group mass
distributions, while high magnification is needed to super-resolve the faintest
objects in the high redshift universe. Inspired by a set of six unusual lens
systems [including five selected from the Sloan Lens ACS (SLACS) and Strong
Lensing Legacy (SL2S) surveys, plus the cluster Abell 1703], we consider
several types of multi-component, physically-motivated lens potentials, and use
the ray-tracing code "glamroc" to predict exotic image configurations. We also
investigate the effects of galaxy source profile and size, and use realistic
sources to predict observable magnifications and estimate very approximate
relative cross-sections. We find that lens galaxies with misaligned disks and
bulges produce swallowtail and butterfly catastrophes, observable as "broken"
Einstein rings. Binary or merging galaxies show elliptic umbilic catastrophes,
leading to an unusual Y-shaped configuration of 4 merging images. While not the
maximum magnification configuration possible, it offers the possibility of
mapping the local small-scale mass distribution. We estimate the approximate
abundance of each of these exotic galaxy-scale lenses to be ~1 per all-sky
survey. In higher mass systems, a wide range of caustic structures are
expected, as already seen in many cluster lens systems. We interpret the
central ring and its counter-image in Abell 1703 as a "hyperbolic umbilic"
configuration, with total magnification ~100 (depending on source size). The
abundance of such configurations is also estimated to be ~1 per all-sky survey.Comment: 21 pages, 30 figures, accepted by MNRAS, copyright material cleared
for re-printing. High-resolution version available from
http://www.slac.stanford.edu/~pjm/atla
Moderating role of organizational identification in the relationship between job demands and burnout
Scant empirical work has tested the implications of the social identity framework in understanding job burnout. In this study, we examined the moderating role of organisational identification in the relationship between job demands (workload and work-home conflict) and job burnout. We viewed stress from the social identity perspective. Survey data were collected from 272 employees (58 females) mean age 34.99 years (SD = 9.59) at a manufacturing company in the Philippines. Data were analysed using hierarchical moderated linear regression. Findings showed that compared to those who scored high on organisational identification, workload impact on job burnout was higher among those scoring as low identifiers. Similarly, the impact of work-home conflict on job burnout of low identifiers was more pronounced compared with high identifiers. This study provides support for one proposition derived from the theory focusing on the moderating role of organizational identification. The results support the viability of a social identity framework in expanding the nomological network of job burnout and highlight the value of integrating a social dimension into an individual-level psychological experience of job burnout. Practical implications of the findings highlight the value of developing social networks and social support for employees in addressing job burnout
Crossover behavior for complex order parameter in high-Tc superconductors
A number of recent experiments have suggested the presence of either real or
complex components in the gap symmetry of high- superconductors (HTSC). In
this paper we introduce a novel approach to study the competition of such
complex order parameter mixtures by varying the position of the two-body
attractive potential in a two dimensional extended Hubbard Hamiltonian. We show
that this procedure explain a number of experimental results and on the
theoretical side, it may be related with certain HTSC microscopic models like
the spin fluctuation theory. Following current trends we concentrate on the
study of order parameter with a component of the type or
a s-wave like and symmetry. We show that the position of
the optimal s-component peak changes with the position parameter while the
d-component occurs always in the optimally region around hole content .Comment: 6 pages in RevTex, 5 figs. in epsi, accepted in the Physica
Paper Session I-B - Science and Application Payloads in the 90\u27s
During the 90\u27s with the operation of the Extended Duration Orbiter (EDO), Space Station Freedom (SSF), large platforms in polar and geosynchronus orbits around the Earth, and supporting systems and technology, an infrastructure will exist that will offer a wide range of opportunities for science and applications payloads. The Marshall Space Flight Center (MSFC) is in a unique position of studying for NASA science missions for all of these systems. This paper will discuss a variety of payloads being studied for NASA at the MSFC that are scheduled for flight in the 90\u27s, in support of space science and Mission to Planet Earth. These science payloads such as the Controls, Astrophysics and Structures Experiment in Space (CASES), Advanced Solar Observatory (ASO), Laser Atmospheric Wind Sounder (LAWS), and Lightning Imaging Sensor (LIS), etc. will fully utilize the capabilities of the EDO, SSF, Earth Observation System (EOS), and Earth Science Geostationary Platform (ESGP). Emphasis will be placed on showing how these scientific payloads can fully exploit the great potential of these new capabilities for exciting new science and application missions
Extension Programming for Food Entrepreneurs: An Indiana Needs Assessment
The objective of the research reported here was to identify the needs of food entrepreneurs in the state of Indiana. To attain this objective, Purdue Extension educators from 86 counties in Indiana were surveyed. Topics of interest from the survey results included marketing, new business start-up, food regulations, and food safety. This assessment tool has directed Purdue Extension in developing a Food Entrepreneur Engagement Program. The survey results were used to develop a statewide workshop for food entrepreneurs. Resources provided by this program ultimately helped several food entrepreneurs create value-added food businesses in Indiana
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