580 research outputs found
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
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\,
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 () 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 ,
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 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 profiles, which is more pronounced in the line wings. (3)
The presence of a weak magnetic field modifies the spatial variation of the
emergent profiles in the line core, by producing significant
changes in their magnitudes.Comment: 31 pages, 14 figures, Submitted to ApJ, Under revie
To determine the eficacy of DIPSI as a method to screen GDM
Background: Gestational Diabetes Mellitus (GDM) is considered as a transient abnormality of glucose intolerance during pregnancy. Women with GDM and their children are at increased risk of future diabetes. The diagnosis of GDM gives us a unique opportunity in identifying individuals who will be benefited by early therapeutic intervention with diet, exercise and normalizing the weight to delay or possibly even prevent the onset of the disease. The objective of the study was to detect efficacy of Diabetes In Pregnancy Study Group of India (DIPSI) recommended 75g oral glucose challenge test in screening and diagnosis of GDM.Methods: 200 pregnant women attending antenatal clinic during 24-28 weeks of pregnancy were subjected to Diabetes In Pregnancy Study Group of India (DIPSI) recommended 75g oral glucose challenge test (OGCT) as a method to screen and diagnose GDM. All patients were given 75grams of glucose irrespective of the meal and 2 hour venous blood sample was collected. Blood glucose was tested by GOD-POD (glucose oxidase peroxidise) method. Diagnosis of impaired glucose tolerance was made when plasma glucose of ≥120-140mg/dl and diagnosis of GDM was made when the plasma glucose of >140 mg/dl. All of them were followed up till delivery. Descriptive statistics was used to calculate the mean and standard deviation to draw the conclusion of this study.Results: Out of the 200 women subjected to DIPSI recommended 75grams of OGCT 38%, 40% and 22% had normal, impaired and abnormal OGTT results, respectively. Age ≥25yrs, family history of diabetes and BMI ≥25kg/m2 are the commonest risk factors for GDM in the study group.Conclusions: Our study supports the concept of universal screening and the use of DIPSI recommended 75g OGCT for screening and diagnosis of GDM
Obstetric outcome of teenage pregnancies in a tertiary care centre in Mangalore, Karnataka, India
Background: Teenage pregnancy is a social problem affecting maternal and child health. In India, teenage pregnancy is an important public-health problem, although the national policy of the Government of India advocates the minimum legal age of marriage for girls to be 18 years. The aim of the present study was to observe the obstetric outcome in Teenage pregnanciesMethods: A retrospective analysis of all Teenage pregnancies was done over a period of 1 year from August 2014 to July 2015. Case sheets of all teenage mothers delivered during that period were retrieved. Maternal and neonatal outcome were analyzed and compared with pregnant women ≥20 years of age.  Results: 5859 deliveries occurred during the study period, teenage deliveries were 457.The prevalence of teenage deliveries was 7.8%. Cesarean delivery rate was 56% vs 42% (p value0.05). Teenage mothers had increased Low birth weight rates 24% vs 10% (p<0.05).Conclusions: Teenage pregnancies has a negative impact on maternal and perinatal health. Hence strict laws should be enforced to prohibit teenage marriages. Adolescent girls should be educated about safe sex practices, contraception and complications of teenage pregnancies on maternal and child health.
Review on microspheres as a drug delivery carrier
A well designed controlled drug delivery system can overcome some of the problems of conventional therapy and enhance the therapeutic efficacy of a given drug .To obtain maximum therapeutic efficacy, it becomes necessary to deliver the agent to the target tissue in the optimal amount in the right period of time there by causing little toxicity and minimal side effects. There are various approaches in delivering a therapeutic substance to the target site in a sustained controlled release fashion. One such approach is using microspheres as carriers for drugs. In this article importance of microsphere as a novel drug delivery carrier to attain site specific drug delivery was discussed
Combining depth and intensity images to produce enhanced object detection for use in a robotic colony
Robotic colonies that can communicate with each other and interact with their ambient environments can be utilized for a wide range of research and industrial applications. However amongst the problems that these colonies face is that of the isolating objects within an environment. Robotic colonies that can isolate objects within the environment can not only map that environment in de-tail, but interact with that ambient space. Many object recognition techniques ex-ist, however these are often complex and computationally expensive, leading to overly complex implementations. In this paper a simple model is proposed to isolate objects, these can then be recognize and tagged. The model will be using 2D and 3D perspectives of the perceptual data to produce a probability map of the outline of an object, therefore addressing the defects that exist with 2D and 3D image techniques. Some of the defects that will be addressed are; low level illumination and objects at similar depths. These issues may not be completely solved, however, the model provided will provide results confident enough for use in a robotic colony
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