399 research outputs found
Proper-time methods in the presence of non-constant background fields
A formalism is developed to enable the construction of the effective action
and related quantities in QED for the case of time-varying background electric
fields. Some examples are studied and evidence is sought for a possible
transition to a phase in which chiral symmetry is spontaneously broken.
YCTP-P14-94Comment: 13 pages, YCTP-P14-9
Brane fluctuation and the electroweak chiral Lagrangian
We use the external field method to study the electroweak chiral Lagrangian
of the extra dimension model with brane fluctuation. Under the assumption that
the contact terms between the matters of the standard model and KK excitations
are heavily suppressed, we use the standard procedure to integrate out the
quantum fields of KK excitations and the equation of motion to eliminate the
classic fields of KK excitations. At one-loop level, we find that up to the
order , due to the momentum conservation of the fifth dimension and the
gauge symmetry of the zero modes, there is no constraint on the size of extra
dimension. This result is consistent with the decoupling theorem. However,
meaningful constraints can come from those operators in , which can
contribute considerably to some anomalous vector couplings and can be
accessible in the LC and LHC.Comment: Revised version, 20 pages in ReVTeX, to appear in PR
Obstacles against the Tourism Development as an Instrument of Poverty Alleviation in Felicitation Volume of Senior Professor Prema Podimenike
The article describes the negative impact of poverty alleviation in tourism of Sri Lanka based on secondary and time series data that were gathered by Sri Lanka Tourism Development Authority from 1968 to 2014. Additionally, secondary data from Department of Census and Statistics in Sri Lanka and Central Bank of Sri Lanka were employed in the study to examine the key objective. The key objective is to discover potential obstacles against the tourism development as an instrument of poverty alleviation while reviewing the research question that how to improve poverty elimination via tourism development. Pearson correlation analysis and descriptive analysis are used. The study suites two suppositions to accomplish the above mentioned objective focusing empirical evidences. Firstly, there are obstacles to develop tourism industry in Sri Lanka. Secondly, the obstacles affect poverty alleviation via tourism development in Sri Lanka. However, findings of this study reveal that significant relationship between tourism development and poverty alleviation has being damaged by obstacles. We conclude that tourism is a proper instrument to move out from poverty and disparity and suggest that potential obstacles should be managed via tourism development strategies. Therefore this study stimulates for policy makers to refer the present tourism policy and add alternative solutions to unfold issues in Sri Lankan rural tourism industry. Significance of this studis not limited to Sri Lanka and under the limitations; findings, suggestions and conclusions of the study can be utilized to develop rural tourism based national plan in developing world
Fluctuations of the Retarded Van der Waals Force
The retarded Van der Waals force between a polarizable particle and a
perfectly conducting plate is re-examined. The expression for this force given
by Casimir and Polder represents a mean force, but there are large fluctuations
around this mean value on short time scales which are of the same order of
magnitude as the mean force itself. However, these fluctuations occur on time
scales which are typically of the order of the light travel time between the
atom and the plate. As a consequence, they will not be observed in an
experiment which measures the force averaged over a much longer time. In the
large time limit, the magnitude of the mean squared velocity of a test particle
due to this fluctuating Van der Waals force approaches a constant, and is
similar to a Brownian motion of a test particle in an thermal bath with an
effective temperature. However the fluctuations are not isotropic in this case,
and the shift in the mean square velocity components can even be negative. We
interpret this negative shift to correspond to a reduction in the velocity
spread of a wavepacket. The force fluctuations discussed in this paper are
special case of the more general problem of stress tensor fluctuations. These
are of interest in a variety of areas fo physics, including gravity theory.
Thus the effects of Van der Waals force fluctuations serve as a useful model
for better understanding quantum effects in gravity theory.Comment: 14 pages, no figure
The Higher Derivative Expansion of the Effective Action by the String-Inspired Method, Part I
The higher derivative expansion of the one-loop effective action for an
external scalar potential is calculated to order O(T**7), using the
string-inspired Bern-Kosower method in the first quantized path integral
formulation. Comparisons are made with standard heat kernel calculations and
with the corresponding Feynman diagrammatic calculation in order to show the
efficiency of the present method.Comment: 13 pages, Plain TEX, 1 figure may be obtained from the authors,
HD-THEP-93-4
QCD strings with spinning quarks
We construct a consistent action for a massive spinning quark on the end of a
QCD string that leads to pure Thomas precession of the quark's spin. The string
action is modified by the addition of Grassmann degrees of freedom to the
string such that the equations of motion for the quark spin follow from
boundary conditions, just as do those for the quark's position.Comment: REVTeX4, 10 pages, no figure
Factors associated with adoption of the electronic health record system among primary care physicians
Background: A territory-wide Internet-based electronic patient record allows better patient care in different sectors. The engagement of private physicians is one of the major facilitators for implementation, but there is limited information about the current adoption level of electronic medical record (eMR) among private primary care physicians.
Objective: This survey measured the adoption level, enabling factors, and hindering factors of eMR, among private physicians in Hong Kong. It also evaluated the key functions and the popularity of electronic systems and vendors used by these private practitioners.
Methods: A central registry consisting of 4324 private practitioners was set up. Invitations for self-administered surveys and the completed questionnaires were sent and returned via fax, email, postal mail, and on-site clinic visits. Current users and non-users of eMR system were compared according to their demographic and practice characteristics. Student’s t tests and chi-square tests were used for continuous and categorical variables, respectively.
Results: A total of 524 completed surveys (response rate 524/4405 11.90%) were collected. The proportion of using eMR in private clinics was 79.6% (417/524). When compared with non-users, the eMR users were younger (users: 48.4 years SD 10.6 years vs non-users: 61.7 years SD 10.2 years, P<.001); more were female physicians (users: 80/417, 19.2% vs non-users: 14/107, 13.1%, P=.013); possessed less clinical experience (with more than20 years of practice: users: 261/417, 62.6% vs non-user: 93/107, 86.9%, P<.001); fewer worked under a Health Maintenance Organization (users: 347/417, 83.2% vs non-users: 97/107, 90.7%, P<.001) and more worked with practice partners (users: 126/417, 30.2% vs non-users: 4/107, 3.7%, P<.001). Efficiency (379/417, 90.9%) and reduction of medical errors (229/417, 54.9%) were the major enabling factors, while patient-unfriendliness (58/107, 54.2%) and limited consultation time (54/107, 50.5%) were the most commonly reported hindering factors. The key functions of computer software among eMR users consisted of electronic patient registration system (376/417, 90.2%), drug dispensing system (328/417, 78.7%) and electronic drug labels (296/417, 71.0%). SoftLink Clinic Solution was the most popular vendor (160/417, 38.4%).
Conclusions: These findings identified several physician groups who should be targeted for more assistance on eMR installation and its adoption. Future studies should address the barriers of using Internet-based eMR to enhance its adoption
The Casimir force and the quantum theory of lossy optical cavities
We present a new derivation of the Casimir force between two parallel plane
mirrors at zero temperature. The two mirrors and the cavity they enclose are
treated as quantum optical networks. They are in general lossy and
characterized by frequency dependent reflection amplitudes. The additional
fluctuations accompanying losses are deduced from expressions of the optical
theorem. A general proof is given for the theorem relating the spectral density
inside the cavity to the reflection amplitudes seen by the inner fields. This
density determines the vacuum radiation pressure and, therefore, the Casimir
force. The force is obtained as an integral over the real frequencies,
including the contribution of evanescent waves besides that of ordinary waves,
and, then, as an integral over imaginary frequencies. The demonstration relies
only on general properties obeyed by real mirrors which also enforce general
constraints for the variation of the Casimir force.Comment: 18 pages, 6 figures, minor amendment
Effective chiral lagrangian in the chiral limit from the instanton vacuum
We study the effective chiral Lagrangian in the chiral limit from the
instanton vacuum. Starting from the nonlocal effective chiral action, we derive
the effective chiral Lagrangian, using the derivative expansion to order
in the chiral limit. The low energy constants, , , and
are determined and compared with various models and the corresponding empirical
data. The results are in a good agreement with the data. We also discuss about
the upper limit of the sigma meson, based on the present results.Comment: 14 pages, 5 figures, submitted to Phys.Rev.
Effects of School Closures, 2008 Winter Influenza Season, Hong Kong
In winter 2008, kindergartens and primary schools in Hong Kong were closed for 2 weeks after media coverage indicated that 3 children had died, apparently from influenza. We examined prospective influenza surveillance data before, during, and after the closure. We did not find a substantial effect on community transmission
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