1,150 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
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
Spatial variability in HIV prevalence declines in several countries in sub-Saharan Africa
AbstractEvidence suggests substantial declines in HIV prevalence in parts of sub-Saharan Africa. However, the observed aggregate declines at the national level may obscure local variations in the temporal dynamics of the infection. Using spatial scan statistics, we identified marked spatial variability in the within-country declines in HIV prevalence in Tanzania, Malawi, Kenya, and Zimbabwe. Our study suggests that the declines in the national HIV prevalence in some of the SSA countries may not be representative of downward trends in prevalence in areas of high HIV prevalence, as much as the result of sharp declines in prevalence in areas of already low HIV prevalence. Our findings provide insights for resource allocation and HIV prevention interventions in these countries
Characterizing the transitioning epidemiology of herpes simplex virus type 1 in the USA: Model-based predictions
Background: Herpes simplex virus type 1 (HSV-1) is a prevalent lifelong infection that appears to be undergoing an epidemiologic transition in the United States (US). Using an analytical approach, this study aimed to characterize HSV-1 transitioning epidemiology and estimate its epidemiologic indicators, past, present, and future. Methods: An age-structured mathematical model was developed to describe HSV-1 transmission through oral and sexual modes of transmission. The model was fitted to the National Health and Nutrition Examination Surveys, 1976-2016 data series. Results: HSV-1 seroprevalence was projected to decline from 61.5% in 1970 to 54.8% in 2018, 48.5% in 2050, and 42.0% in 2100. In 30% for those aged 0-19 years, but 60. Meanwhile, the number of new infections per year (oral and genital) was persistent at 2,762,000 in 1970, 2,941,000 in 2018, 2,933,000 in 2050, and 2,960,000 in 2100. Of this total, genital acquisitions contributed 252,000 infections in 1970, 410,000 in 2018, 478,000 in 2050, and 440,000 in 2100 - a quarter of which are symptomatic with clinical manifestations. For those aged 15-49 years, nearly 25% of incident infections are genital. Most genital acquisitions (> 85%) were due to oral-to-genital transmission through oral sex, as opposed to genital-to-genital transmission through sexual intercourse. Conclusion: HSV-1 epidemiology is undergoing a remarkable transition in the US, with less exposure in childhood and more in adulthood, and less oral but more genital acquisition. HSV-1 will persist as a widely prevalent infection, with ever-increasing genital disease burden.This publication was made possible by NPRP grant number 9-040-3-008 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. The authors are also grateful for pilot funding provided by the Biomedical Research Program and infrastructure support provided by the Biostatistics, Epidemiology, and Biomathematics Research Core, both at Weill Cornell Medicine in Qatar
Π ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π°Ρ ΡΡΠ½ΠΊΠ° ΡΡΠ°Π½ΠΊΠΎΡΡΡΠΎΠ΅Π½ΠΈΡ Ρ ΠΏΠΎΠ·ΠΈΡΠΈΠΉ Π°Π½Π°Π»ΠΈΠ·Π° ΠΌΠΈΡΠΎΠ²ΡΡ ΡΠ΅Π½Π΄Π΅Π½ΡΠΈΠΉ, ΠΊΠΎΠ½ΡΠ΅ΠΏΡΠΈΠΈ ΠΆΠΈΠ·Π½Π΅Π½Π½ΠΎΠ³ΠΎ ΡΠΈΠΊΠ»Π° ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ ΠΈ CALS-ΡΠ΅Ρ Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ
Π ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΡΡΡΠ΅ΡΡΠ²ΡΡΡΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄ΠΈΠΊΠΈ Π²ΡΠ±ΠΎΡΠ° ΠΈ ΠΏΡΠΎΠ΅ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π½ΠΎΠ²ΠΎΠ³ΠΎ ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ Ρ ΠΏΠΎΠ·ΠΈΡΠΈΠΉ Π°Π½Π°Π»ΠΈΠ·Π° Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
Π²ΠΈΠ΄Π°Ρ
ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ, ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΡΡΡ Π°Π½Π°Π»ΠΈΠ· Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΊΠΎΠ² "ΠΊΠ»Π°ΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ" ΠΏΠΎΠ΄Ρ
ΠΎΠ΄Π° ΠΊ Π²ΡΠ±ΠΎΡΡ ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ CALS-ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ, ΠΏΡΠΈΠ½ΡΠΈΠΏΠ° Π°Π³ΡΠ΅Π³Π°ΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΠΏΠ°ΡΠΏΠΎΡΡΠΈΠ·Π°ΡΠΈΠΈ ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ΅Π΄Π»Π°Π³Π°Π΅ΡΡΡ Π½ΠΎΠ²Π°Ρ ΠΌΠΎΠ΄Π΅Π»Ρ ΠΏΡΠΎΠ΅ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡΠ°Ρ ΠΏΡΠΎΠ΄Π»ΠΈΡΡ ΠΆΠΈΠ·Π½Π΅Π½Π½ΡΠΉ ΡΠΈΠΊΠ» ΡΡΠ°Π½ΠΊΠΎΠ², ΡΠΌΠ΅Π½ΡΡΠΈΡΡ ΡΡΠΎΠΈΠΌΠΎΡΡΡ ΠΈ ΡΡΠΎΠΊΠΈ ΠΏΡΠΎΠ΅ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΎΠ±ΠΎΡΡΠ΄ΠΎΠ²Π°Π½ΠΈΡ.This article reviews the existing methods of choice and design of new equipment from the standpoint of analyzing the most effective forms of treatment, an analysis of the shortcomings of "classical" approach to the choice of equipment. Based on CALS-technologies, the principle of aggregation and certification of equipment, a new model for the design of equipment are proposed. This model allows to extend the life cycle of machines, reduce the cost and terms of designing and manufacturing equipment
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