Multi-dimensional radiative transfer to analyze Hanle effect in Ca {\sc ii} K line at 3933 \AA\,

Radiative transfer (RT) studies of the linearly polarized spectrum of the Sun (the second solar spectrum) have generally focused on the line formation, with an aim to understand the vertical structure of the solar atmosphere using one-dimensional (1D) model atmospheres. Modeling spatial structuring in the observations of the linearly polarized line profiles requires the solution of multi-dimensional (multi-D) polarized RT equation and a model solar atmosphere obtained by magneto-hydrodynamical (MHD) simulations of the solar atmosphere. Our aim in this paper is to analyze the chromospheric resonance line Ca {\sc ii} K at 3933 \AA\ using multi-D polarized RT with Hanle effect and partial frequency redistribution in line scattering. We use an atmosphere which is constructed by a two-dimensional snapshot of the three-dimensional MHD simulations of the solar photosphere, combined with columns of an 1D atmosphere in the chromosphere. This paper represents the first application of polarized multi-D RT to explore the chromospheric lines using multi-D MHD atmospheres, with PRD as the line scattering mechanism. We find that the horizontal inhomogeneities caused by MHD in the lower layers of the atmosphere are responsible for strong spatial inhomogeneities in the wings of the linear polarization profiles, while the use of horizontally homogeneous chromosphere (FALC) produces spatially homogeneous linear polarization in the line core

Polarized Line Formation in Multi-Dimensional Media.III. Hanle Effect with Partial Frequency Redistribution

In the previous two papers, namely, \citet{anuknn11} and \citet{anuetal11} we solved the polarized radiative transfer (RT) equation in multi-dimensional (multi-D) geometries, with partial frequency redistribution (PRD) as the scattering mechanism. We assumed Rayleigh scattering as the only source of linear polarization ($Q/I, U/I$) in both these papers. In this paper we extend these previous works to include the effect of weak oriented magnetic fields (Hanle effect) on line scattering. We generalize the technique of Stokes vector decomposition in terms of the irreducible spherical tensors $\mathcal{T}^K_Q$, developed in \citet{anuknn11}, to the case of RT with Hanle effect. A fast iterative method of solution (based on the Stabilized Preconditioned Bi-Conjugate-Gradient technique), developed in \citet{anuetal11}, is now generalized to the case of RT in magnetized three-dimensional media. We use the efficient short-characteristics formal solution method for multi-D media, generalized appropriately to the present context. The main results of this paper are the following: (1) A comparison of emergent $(I, Q/I, U/I)$ profiles formed in one-dimensional (1D) media, with the corresponding emergent, spatially averaged profiles formed in multi-D media, shows that in the spatially resolved structures, the assumption of 1D may lead to large errors in linear polarization, especially in the line wings. (2) The multi-D RT in semi-infinite non-magnetic media causes a strong spatial variation of the emergent $(Q/I, U/I)$ profiles, which is more pronounced in the line wings. (3) The presence of a weak magnetic field modifies the spatial variation of the emergent $(Q/I, U/I)$ profiles in the line core, by producing significant changes in their magnitudes.Comment: 31 pages, 14 figures, Submitted to ApJ, Under revie

Pressure and current balance conditions during electron beam injections from spacecraft

Electrostatic charging level of a conducting surface in response to injections of electron beams into space plasma is investigated by means of one-dimensional Vlasov code. Injections of Maxwellian beams into a vacuum shows that the surface can charge up to an electric potential phi sub s greater than W sub b, where W sub b is the average electron beam energy. Since Maxwellian beams have extended trails with electrons having energies greater than W sub b, it is difficult to quantify the charging level in terms of the energies of the injected electrons. In order to quantitatively understand the charging in excess of W sub b, simulations were carried out for water-bag types of beam with velocity distribution functions described by f(V) = A for V sub min approx. less than V approx. less than V sub max and f(V) = O otherwise, where A is a constant making the normalized beam density unity. It is found that V sub max does not directly determine the charging level. The pressure distribution in the electron sheath determines the electric field distribution near the surface. The electric field in turn determines the electrostatic potential of the vehicle. The pressure distribution is determined by the beam parameters such as the average beam velocity and the velocity spread of the beam

Effect of cross-redistribution on the resonance scattering polarization of O {\sc i} line at 1302 \AA\,

Oxygen is the most abundant element on the Sun after Hydrogen and Helium. The intensity spectrum of resonance lines of neutral Oxygen namely O {\sc i} (1302, 1305 and 1306 \AA\,) has been studied in the literature for chromospheric diagnostics. In this paper we study the resonance scattering polarization in the O {\sc i} line at 1302 \AA\, using two-dimensional radiative transfer in a composite atmosphere constructed using a two-dimensional magneto-hydrodynamical snapshot in the photosphere and columns of the one-dimensional FALC atmosphere in the chromosphere. The methods developed by us recently in a series of papers to solve multi-dimensional polarized radiative transfer have been incorporated in our new code POLY2D which we use for our analysis. We find that multi-dimensional radiative transfer including XRD effects is important in reproducing the amplitude and shape of scattering polarization signals of the O {\sc i} line at 1302 \AA\,

Study of the antibiotic sensitivity pattern of bloodstream infections in gynaecological ICU

Background: Severe sepsis is one of the leading causes of death even in the developed nation, among critically ill patients admitted in intensive care units (ICU). Decreasing antibiotic susceptibility with increasing length of hospital stay increases the burden on the healthcare system.Methods: A total of 75 samples taken from the patients suspected with bloodstream infection in the gynaecological ICU were processed as per standard protocol. Identification of bacteria was carried out with the help of relevant biochemical tests. Antibiotic susceptibility testing was done by Kirby-Bauer Disk diffusion method according to CLSI guidelines.Results: Positive blood culture was seen in 21 (28%) samples. Out of these 13 (61.90%) were gram negative bacteria and 8 (38.09%) was gram positive cocci. Escherichia spp., Klebsiella spp. and Acinetobacter spp. were the predominant isolates in gram negative bacteria. Gentamicin, Piperacillin-Tazobactam, Imipenem and Levofloxacin were the most sensitive antibiotics while Cefazolin, Cefuroxime, Cefepime and Ceftazidime were the most resistant antibiotics.Conclusions: Gram negative bacteria are an emerging cause of sepsis in ICU patients while gram positive bacteria still remain prevalent. The purpose of this study is to identify the bacterial cause of septicaemia in general intensive care unit (GICU) patients

Characteristics of blood infections and phenotypic detection of extended-spectrum β-lactamases in ICU patients in Central India posing a challenge

Background: Bloodstream infection (BSI) is defined by positive blood cultures in a patient with systemic signs of infection and may be either secondary to a documented source or primary, that is, without identified origin. The aim of this study was to improvise blood culture systems for a quicker, optimum diagnosis and prompt treatment. Methods: A prospective study was conducted with total of 309 samples for determining the bacteriological profile and prevalence of ESBL in BSI’s in patients admitted in the ICU’s (surgical/medical/gynaecological) with the suspicion of sepsis. Samples received in department of microbiology were processed as per standard protocol and identification of bacteria was carried out with the help of relevant biochemical tests. AST for both the ICUs was done together by Kirby-Bauer disk diffusion method according to CLSI guidelines. Results: Of the total, 149 (48.22%) samples were positive for growth with the major isolates out of these being gram negative bacilli, 104 (69.79%) and 45 (30.21%) were gram positive cocci. Among the gram negative bacilli, Klebsiella pneumoniae 35 (33.65%) was the most common bacteria while the least frequent organism isolated was Acinetobacter baumanii 10 (9.62%). Imipenem, piperacillin-tazobactam and levofloxacin were the most sensitive antibiotics whereas cefepime, cefuroxime were the most resistant antibiotics. Conclusions: This study highlights the incidence of gram negative bacilli in ICU’s and the emergence of multi-drug resistant organism. Infections with MDR organisms can lead to inadequate or delayed treatment which is associated with adverse patient outcomes

ChemInform Abstract: A Facile Synthesis of N‐Z/Boc‐Protected 1,3,4‐Oxadiazole‐Based Peptidomimetics Employing Peptidyl Thiosemicarbazides.

A convenient protocol is presented for the cyclization of dipeptidyl thiosemicarbazides (III)

The diffraction of light by high frequency sound waves. Part III. Doppler effect and coherence phenomena

The theory developed in part I of this series of papers has been developed in this paper to find the Doppler effects in the diffraction components of light produced by the passage of light through a medium containing (1) a progressive supersonic wave and (2) a standing supersonic wave. (1) In the case of the former the theory shows that the nth order which is inclined at an angle sin-1 (-nλ/λ∗) to the direction of the propagation of the incident light has the frequency ν-nν∗ where ν is the frequency of light, ν∗ is the frequency of sound and n is a positive or negative integer and that the nth order has the relative intensity J2n(2πμL/λ) where μ is the maximum variation of the refractive index, L is the distance between the faces of the cell of incidence and emergence and λ is the wavelength of light. (2) In the case of a standing supersonic wave; the diffraction orders could be classed into two groups, one containing the even orders and the other odd orders; any even order, say 2n, contains radiations with frequencies ν±2rν∗ where r is an integer including zero, the relative intensity of the ν±2rν∗ sub-component being J2n-r(πμL/λ) J2n+r(πμL/λ); and odd order, say 2n+1, contains radiations with frequencies ν ± 2r+1̅ν∗, the relative intensity of the ν ± 2r+1̅ν∗ sub-component being J2n-r , (πμL/λ) J2n+r+1(πμL/λ). These results satisfactorily interpret the recent results of Bar that any two odd orders or even ones partly cohere while an odd one and an even one are incoherent