1,222 research outputs found
The nucleon and the nuclear force in the context of effective theory and path-integral methods
The nucleon structure and the nuclear force are investigated in the context
of the non-perturbative path-integral method of hadronization. Starting from a
microscopic quark-diquark model, the nucleon is generated as a relativistic
bound state and an effective chiral meson-nucleon Lagrangian is derived. Many
of the nucleon physical properties are studied using a theory of at most two
free parameters.Comment: 8 pages, 4 figures. To appear in the proceedings of Pan American
Advanced Studies Institute on New States of Matter in Hadronic Interactions
(PASI2002), Campos do Jordao, Brazil, 7-18 Jan 200
Quasifree processes from nuclei: Meson photoproduction and electron scattering
We have developed a relativistic formalism for studying quasi-free processes
from nuclei. The formalism can be applied with ease to a variety of processes
and renders transparent analytical expressions for all observables. We have
applied it to kaon photoproduction and to electron scattering. For the case of
the kaon, we compute the recoil polarization of the lambda-hyperon and the
photon asymmetry. Our results indicate that polarization observables are
insensitive to relativistic, nuclear target, and distortion effects. Yet, they
are sensitive to the reactive content, making them ideal tools for the study of
modifications to the elementary amplitude -- such as in the production,
propagation, and decay of nucleon resonances -- in the nuclear medium. For the
case of the electron, we have calculated the spectral function of He-4. An
observable is identified for the clean and model-independent extraction of the
spectral function. Our calculations provide baseline predictions for the
recently measured, but not yet fully analyzed, momentum distribution of He-4 by
the A1-collaboration from Mainz. Our approach predicts momentum distributions
for He-4 that rival some of the best non-relativistic calculations to date.Comment: To appear in the proceedings of International Symposium on
Electromagnetic Interactions in Nuclear and Hadron Physics (EMI 2001), Osaka,
Ibaraki, Japan, 4-7 Dec 200
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Epidemiological impact of targeted interventions for people with diabetes mellitus on tuberculosis transmission in India: Modelling based predictions.
INTRODUCTION: Diabetes mellitus (DM) is a leading driver of tuberculosis (TB) disease in TB-DM burdened countries. We aimed to assess the impact on TB disease of several intervention strategies targeting people with DM in India. METHODS: A previously validated TB-DM mathematical model was extended to include interventions targeting DM individuals. The model stratified the population by age, DM status, TB infection status and stage, TB disease form, treatment, recovery, and intervention status. RESULTS: By 2050, different TB vaccination strategies (coverage of 50 % and vaccine efficacies ranging between 50 %-60 %) reduced TB incidence and mortality rates by 4.5 %-20.8 % and 4.1 %-22.1 %, respectively, and averted 3.1 %-12.8 % of TB disease cases in the total population. Number of vaccinations needed to avert one TB case (effectiveness) was 14-105. Varying the coverage levels of latent TB treatment (coverage of 50 %-80 % and drug effectiveness of 90 %) reduced TB incidence and mortality rates by 7.1 %-11.3 % and 8.2 %-13.0 %, respectively, averting 4.2 %-6.7 % of TB cases, with effectiveness of 38-40. Different scenarios for dual and concurrent treatment of those with TB and DM, reduced TB incidence and mortality rates by 0.1 %-0.4 % and 1.3 %-4.8 %, respectively, averting 0.1 %-0.2 % of TB cases, with effectiveness of 28-107. Different scenarios for managing and controlling DM (regardless of TB status) reduced TB incidence and mortality rates by 4.5 %-16.5 % and 6.5 %-22.2 %, respectively, averting 2.9 %-10.8 % of TB cases, with effectiveness of 6-24. CONCLUSION: Gains can be attained by targeting DM individuals with interventions to reduce TB burden. Most strategies were effective with <50 intervention doses needed to avert one TB disease case, informing key updates of current treatment guidelines
Urban development and expansion trends under the political instability in palestine: jerusalem- ramallah case study
Urban development, expansion, and Land use changes in the urban environments are a global
phenomenon, by 2050, urban population in the world will increase to be more than 6.6 billion
inhabitants and they will live with less than 1% of the world land surfaces. Political instability
is one of most important drivers that effecting on the land cover/land use change and urban
expansion, especially in the areas that faced the political problems and wars. Urban development in
Occupied Palestinian Territories (OPT) impacted strongly by Political Transformations during 20th
century and early of 21th century. The political instability factor in OPT leaded to distortion of
Palestinian urban form and effecting on future urban expansion and development. Therefore, this study
aims to assess of urban development and planning in Palestine during the political transformation
stages, as well as it aims to explore urban expansion trends under the geopolitical effects in Jerusalem
– Ramallah urban region as a model in the Palestinian urban environment. Descriptive, historical,
and cartographic methods conducted based on used Geographic Information System to explore
existing and future urban expansion trends in Jerusalem – Ramallah region as a case and model in the
Palestinian urban environments. The result showed how the political instability conditions effected
strongly on the urban development process and expansion in the Occupied Palestinian Territories.
Therefore, this study will improve our Knowledge in the urban development research context about the
relationship between the urban development and the political transformations. Palestinian policy
makers and planners, as well as Palestinian planning organizations at different levels need to put more
efforts to prepare of the regional, sub-regional , and master plans for all Palestinian localities and
regions especially in the OPT, in the conflict and sensitive areas such as Jerusalem –Ramallah region.
This study recommend to adaption a new planning ideas and strategies to face the Israeli physical
planning in the Palestinian urban environments like compact communities and principles of smart urban
growth
How Does Population Viral Load Vary with the Evolution of a Large HIV Epidemic in sub-Saharan Africa?
Using mathematical modelling, we described the temporal evolution of population HIV-1 viral load in Tanzania throughout the epidemic. Population log10 viral load was found to be stable and not sensitive to epidemic dynamics. However, even modest increases in antiretroviral therapy (ART) coverage were reflected as appreciable reductions in population log10 viral load. As ART coverage expands in sub-Saharan Africa, population log10 viral load will increasingly become a powerful proxy for monitoring ART implementation and HIV incidence trends. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivitives 3.0 License, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially. http://creativecommons.org/licenses/by-nc-nd/3.0
Quasifree kaon-photoproduction from nuclei in a relativistic approach
We compute the recoil polarization of the lambda-hyperon and the photon
asymmetry for the quasifree photoproduction of kaons in a relativistic
impulse-approximation approach. Our motivation for studying polarization
observables is threefold. First, polarization observables are more effective
discriminators of subtle dynamics than the unpolarized cross section. Second,
earlier nonrelativistic calculations suggest an almost complete insensitivity
of polarization observables to distortions effects. Finally, this insensitivity
entails an enormous simplification in the theoretical treatment. Indeed, by
introducing the notion of a ``bound-nucleon propagator'' we exploit Feynman's
trace techniques to develop closed-form, analytic expressions for all
photoproduction observables. Moreover, our results indicate that polarization
observables are also insensitive to relativistic effects and to the nuclear
target. Yet, they are sensitive to the model parameters, making them ideal
tools for the study of modifications to the elementary amplitude --- such as in
the production, propagation, and decay of nucleon resonances --- in the nuclear
medium.Comment: 15 pages and 6 figures - submitted to PR
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