A variational perturbation scheme for many-particle systems in the functional integral approach

A variational Perturbation theory based on the functional integral approach is formulated for many-particle systems. Using the variational action obtained through Jensen-Peierls' inequality, a perturbative expansion scheme for the thermodynamic potential is established. A modified Wick's theorem is obtained for the variational perturbation expansions. This theorem allows one to carry out systematic calculations of higher order terms without worrying about the double counting problem. A model numerical calculation was carried out on a nucleon gas system interacting through the Yukawa-type potential to test the efficiency of the present method.Comment: accepted for publication in Phys. Rev.

Rayleigh-Schroedinger-Goldstone variational perturbation theory for many fermion systems

We present a Rayleigh-Schroedinger-Goldstone perturbation formalism for many fermion systems. Based on this formalism, variational perturbation scheme which goes beyond the Gaussian approximation is developed. In order to go beyond the Gaussian approximation, we identify a parent Hamiltonian which has an effective Gaussian vacuum as a variational solution and carry out further perturbation with respect to the renormalized interaction using Goldstone's expansion. Perturbation rules for the ground state wavefunctional and energy are found. Useful commuting relations between operators and the Gaussian wavefunctional are also found, which could reduce the calculational efforts substantially. As examples, we calculate the first order correction to the Gaussian wavefunctional and the second order correction to the ground state of an electron gas system with the Yukawa-type interaction.Comment: 11pages, 1figur

A new approximation scheme in quantum mechanics

An approximation method which combines the perturbation theory with the variational calculation is constructed for quantum mechanical problems. Using the anharmonic oscillator and the He atom as examples, we show that the present method provides an efficient scheme in estimating both the ground and the excited states. We also discuss the limitations of the present method.Comment: 14pages, to be published in Eur. J. Phy

A Variational Expansion for the Free Energy of a Bosonic System

In this paper, a variational perturbation scheme for nonrelativistic many-Fermion systems is generalized to a Bosonic system. By calculating the free energy of an anharmonic oscillator model, we investigated this variational expansion scheme for its efficiency. Using the modified Feynman rules for the diagrams, we obtained the analytical expression of the free energy up to the fourth order. Our numerical results at various orders are compared with the exact and other relevant results.Comment: 9 pages, 3 EPS figures. With a few typo errors corrected. to appear in J. Phys.

Variational perturbation approach to the Coulomb electron gas

The efficiency of the variational perturbation theory [Phys. Rev. C {\bf 62}, 045503 (2000)] formulated recently for many-particle systems is examined by calculating the ground state correlation energy of the 3D electron gas with the Coulomb interaction. The perturbation beyond a variational result can be carried out systematically by the modified Wick's theorem which defines a contraction rule about the renormalized perturbation. Utilizing the theorem, variational ring diagrams of the electron gas are summed up. As a result, the correlation energy is found to be much closer to the result of the Green's function Monte Carlo calculation than that of the conventional ring approximation is.Comment: 4 pages, 3 figure

Association Between Sensitization to Outdoor Spider Mites and Clinical Manifestations of Asthma and Rhinitis in the General Population of Adults

It has been demonstrated that spider mites such as the two-spotted spider mite (Tetranychus urticae) are important allergens for fruit farmers. A total of 2,467 adults (795 metropolitan urban, 788 non-metropolitan urban, and 884 rural subjects) were enrolled. They responded to the questionnaire, and underwent methacholine bronchial provocation tests as well as skin prick tests to locally common aeroallergens including the two-spotted spider mite. The prevalences of asthma and rhinitis as reported on the questionnaire were 7.8% and 16.4% of adults aged 20-35, 9.4% and 24.7% of those 36-50, and 17.7% and 21.7% of those older than 50, respectively. Among the older group, the two-spotted spider mite was the most common sensitizing allergen, although it was second of that of house dust mites among the other two age groups. Sensitization to the two-spotted spider mite was significantly associated with the prevalence of asthma and rhinitis among the younger age group, and associated with the prevalence of rhinitis among the older age group. The two-spotted spider mite might be a common sensitizing allergen in the general population of adults, and sensitization to this mite may play a role in the manifestation of asthma and rhinitis symptoms during adulthood

Physicians' Preferences for Asthma Guidelines Implementation

Purpose: Patient care based on asthma guidelines is cost-effective and leads to improved treatment outcomes. However, ineffective implementation strategies interfere with the use of these recommendations in clinical practice. This study investigated physicians` preferences for asthma guidelines, including content, supporting evidence, learning strategies, format, and placement in the clinical workplace. Methods: We obtained information through a questionnaire survey. The questionnaire was distributed to physicians attending continuing medical education courses and sent to other physicians by airmail, e-mail, and facsimile. Results: A total of 183 physicians responded (male to female ratio, 2.3:1; mean age, 40.4 +/- 9.9 years); 89.9% of respondents were internists or pediatricians, and 51.7% were primary care physicians. Physicians preferred information that described asthma medications, classified the disease according to severity and level of control, and provided methods of evaluation/treatment/monitoring and management of acute exacerbation. The most effective strategies for encouraging the use of the guidelines were through continuing medical education and discussions with colleagues. Physicians required supporting evidence in the form of randomized controlled trials and expert consensus. They preferred that the guidelines be presented as algorithms or flow charts/flow diagrams on plastic sheets, pocket cards, or in electronic medical records. Conclusions: This study identified the items of the asthma guidelines preferred by physicians in Korea. Asthma guidelines with physicians` preferences would encourage their implementation in clinical practice.This study was supported by grants from the Ministry for Health, Welfare and Family Affairs, R.O.K. (A040153).*GLOB IN ASTHM, 2009, GLOB STRAT ASTHM MANGILDENHUYS J, 2009, INT J EMERG MED, V2, P33YOO KH, 2007, J ASTHMA ALLERGY CLI, V27, P226Barosi G, 2006, NEUROL SCI, V27, pS231, DOI 10.1007/s10072-006-0624-9Cho SH, 2006, J KOREAN MED SCI, V21, P181Burr ML, 2006, THORAX, V61, P296, DOI 10.1136/thx.2005.045682CHO SH, 2006, KOREAN J MED, V70, P69KIM YS, 2006, TUBERCULOSIS RESP DI, V61, P121YOO KH, 2006, J ASTHMA ALLERGY CLI, V26, P282STONE TT, 2005, QUAL MANAG HLTH CARE, V14, P177Lai CKW, 2003, J ALLERGY CLIN IMMUN, V111, P263, DOI 10.1067/mai.2003.30LEE EK, 2003, TUBERC RESP DIS, V55, P165Kim YK, 2002, CLIN EXP ALLERGY, V32, P1706Ting S, 2002, ANN ALLERG ASTHMA IM, V88, P326*KOR I HLTH SOC AF, 2002, ASTHM MED US EVGROSS PA, 2001, MED CARE, V39, P85Crim C, 2000, CHEST, V118, p62SHartert TV, 2000, J AM GERIATR SOC, V48, P651Stone TT, 1999, AM J MED QUAL, V14, P170Doerschug KC, 1999, AM J RESP CRIT CARE, V159, P1735Beasley R, 1998, LANCET, V351, P1225*KOR AC ASTHM ALL, KOR GUID AD ASTHM TR