Periodic response of nonlinear systems

A procedure is developed to determine approximate periodic solutions of autonomous and non-autonomous systems. The trignometric collocation method (TCM) is formalized to allow for the analysis of relatively small order systems directly in physical coordinates. The TCM is extended to large order systems by utilizing modal analysis in a component mode synthesis strategy. The procedure was coded and verified by several check cases. Numerical results for two small order mechanical systems and one large order rotor dynamic system are presented. The method allows for the possibility of approximating periodic responses for large order forced and self-excited nonlinear systems

Theoretical studies of the atomic transitions in boron-like ions: Mg VIII, Si X and S XII

In this paper, we have carried out the calculations of the weighted oscillator strengths and the transition probabilities for a few low-lying transitions of boron-like ions: Mg VIII, Si X and S XII which are astrophysically important, particularly, in the atmospheres of the solar corona. We have employed an all-order relativistic many-body theory called the relativistic coupled-cluster theory to calculate very precisely these atomic quantities of astrophysical interest. We have reported for the first time the transition probabilities for some forbidden transitions which are unavailable in the literature; either theoretically or experimentally. We also discuss the physical effects associated with these transitions. Our data can be used for the identification of spectral lines arising from the coronal atmospheres of Sun and Sun-like stars having an extended corona.Comment: 8 pages, 4 table

The electron electric dipole moment enhancement factors of Rubidium and Caesium atoms

The enhancement factors of the electric dipole moment (EDM) of the ground states of two paramagnetic atoms; rubidium (Rb) and caesium (Cs) which are sensitive to the electron EDM are computed using the relativistic coupled-cluster theory and our results are compared with the available calculations and measurements. The possibility of improving the limit for the electron EDM using the results of our present work is pointed out.Comment: AISAMP7 Conference paper, Accepted in Journal of Physics: Conference Series: 200

Relativistic calculations of the lifetimes and hyperfine structure constants in 67^{67}Zn+^{+}

This work presents accurate {\it ab initio} determination of the magnetic dipole (M1) and electric quadrupole (E2) hyperfine structure constants for the ground and a few low-lying excited states in $^{67}$Zn$^{+}$, which is one of the interesting systems in fundamental physics. The coupled-cluster (CC) theory within the relativistic framework has been used here in this calculations. Long standing demands for a relativistic and highly correlated calculations like CC can be able to resolve the disagreements among the lifetime estimations reported previously for a few low-lying states of Zn$^{+}$. The role of different electron correlation effects in the determination of these quantities are discussed and their contributions are presented.Comment: 9 pages, 1 figure. submitted to J. Phys. B Fast Trac

Theoretical determination of lifetimes of metastable states in Sc III and Y III

Lifetimes of the first two metastable states in Sc^{2+} and Y^{2+} are determined using the relativistic coupled-cluster theory. There is a considerable interest in studying the electron correlation effects in these ions as though their electronic configurations are similar to the neutral alkali atoms, their structures are very different from the latter. We have made a comparative study of the correlation trends between the above doubly ionized systems with their corresponding neutral and singly ionized iso-electronic systems. The lifetimes of the excited states of these ions are very important in the field of astrophysics, especially for the study of post-main sequence evolution of the cool giant stars.Comment: 13 pages, 1 figure and 5 table

Rational Pension Reform

This paper is motivated by the idea to create, wherever possible, rational mechanisms that adapt pension systems automatically to a changed economic and demographic environment, rather than to leave such adaptations to discretionary high-profile pension reforms which all too often stir political opposition. The paper delineates the theory behind such rational mechanisms, shows the advantages and limits of „self-stabilizing“ pension systems, and compares the Swedish and the German approaches to rule-bound pension policy

Study of resistance pattern of isolated micro-organisms towards commonly used anti-microbial agents in medical intensive care unit of a tertiary care teaching hospital

Background: The objective of the study was to find out different types of biological samples from admitted patients tested for culture and sensitivity (C&S), prevalence of different types of organisms isolated from those samples, and to analyze the resistance pattern of those isolated organisms against commonly used or tested anti-microbial agents (AMAs).Methods: Following institutional ethics committee approval and written informed consent, adult patients of both genders, receiving AMAs were enrolled from June 2014 to July 2015 and followed up daily till they were in medical intensive care unit (MICU). Demographic data, diagnosis, culture-sensitivity (antibiogram) and other investigation reports and treatment details were recorded. Descriptive statistical analysis of collected data was done.Results: Of the 514 samples (from 600 patients enrolled) sent for C&S testing, 143 were reported as sterile while from the rest 371 samples, 504 organisms were isolated; commonly isolated organisms were Pseudomonas aeruginosa (30%), Acinetobacter baumannii (23%), Klebsiella pneumoniae (16%), Providencia sp. (7.1%), Escherichia coli (5.7%), and Enterobacter sp. (4.2%). Samples were sent in 63% of enrolled patients, the commonest being broncho-alveolar lavage (48% of total). Microbial resistance was high for cephalosporins (ceftriaxone, cefepime, ceftazidime), carbapenems (meropenem, imipenem), penicillins (piperacillin), quinolones (ciprofloxacin, levofloxacin), aminoglycosides (gentamicin, netilmicin, amikacin) and cotrimoxazole. Most organisms were sensitive to colistin (100%), polymyxin B (92%) and tigecycline (69%).Conclusions: The information regarding commonly isolated organisms and their resistant pattern would aid in rational selection of AMAs and thus the present study is useful to clinicians managing MICU and the hospital infection committee to plan future policies regarding AMA use in MICU