No abstract

No abstract

A general dispersion relation for the high frequency domain in a (u ? X i ) partially, ionized, inhomogeneous and magnetised plasma is derived by incorporating neutral dynamics. Plasma and neutral Ñuids are described by basic two Ñuids and MaxwellÏs equation [Alfve n, H. and Falthammar, C. G., ""Cosmical ElectrodynamicsÏÏ (Oxford 1963)]. It is emphasized that the introduction of neutral dynamics not only generates neo-modes or neoclasses of instabilities but also modiÐes earlier results [Huba, J. D., Phys. Fluids B3, 3217 (1991) and Phys. Plasma 2, 2504.]. The importance of a magnetic Ðeld gradient with neutral density gradient in generating these modes has also been demonstrated. The probable candidacy of the Ðndings is discussed.

No abstract

Introduction : Health care workers (HCW) are among the most vulnerable for contracting the COVID-19 infection. Understanding the extent of human-to-human transmission of the COVID-19 infection among HCW is critical in management of this infection and for policy making. We did this study to observe seropositivity and estimate new infection by seroconversion among HCW and predict the risk factors for infection.  Methods : A cohort study was conducted at a tertiary dedicated COVID-19 hospital in New Delhi during first and second wave of the COVID-19 pandemic. All HCW working in the hospital during the study period who come in contact with the patients, were our study population. The data was collected by a detailed face to face interview along with serological assessment for anti- COVID-19 antibodies at baseline and endline, and assessment of daily symptoms.  Prediction of potential risk factors for seroprevalence and seroconversion was done by logistic regression keeping the significance at p<0.05.  Results : A total of 192 HCW were recruited in this study, out of which, 119 (61.97%) at baseline and 108 (77.7%) at endline were seropositive for COVID-19. About two-third (63.5%) had close contact, 5.2% had exposure during aerosol procedures, 30.2% had exposure with a patient’s body fluid while majority (85.4%) had exposure to contact surface around the patient. Almost all were wearing PPE and following IPC measures during their recent contact with a COVID-19 patient. Seroconversion was observed among 36.7% of HCWs while 64.0% had a serial rise in titer of antibodies during the follow-up period. Association of seropositivity was observed negatively with doctors [OR:0.353, CI:0.176-0.710], COVID-19 symptoms [OR:0.210, CI:0.054-0.820], comorbidities [OR:0.139, CI: 0.029 - 0.674], and recent Infection Prevention Control (IPC) training [OR:0.250, CI:0.072 -0.864], while positively associated with partially [OR:3.303, CI: 1.256-8.685], as well as fully vaccination for COVID-19 [OR:2.428, CI:1.118-5.271]. Seroconversion was positively associated with doctor as profession [OR: 13.04, CI: 3.39 - 50.25] and with partially [OR: 4.35, CI: 1.070 -17.647], as well as fully vaccinated for COVID-19 [OR: 6.08, CI: 1.729 - 21.40]. No significant association was observed between adherence to any of the IPC measures and PPE (personal protective equipment) adopted by the HCW during the recent contact with COVID-19 patients and seroconversion. Conclusion : A high seropositivity and seroconversion could be either due to exposure to COVID-19 patients or concurrent immunization against COVID-19 disease. In this study the strongest association of seropositivity and seroconversion was observed with recent vaccination. IPC measures were practiced by almost all the HCW in these settings, and thus were not found to be affecting seroconversion. Further study using anti N antibodies serology, which are positive following vaccination may help us to find out the reason for the seropositivity and seroconversion in HCW.