3,200 research outputs found
Interference of Conversion and Bremsstrahlung Amplitudes in the Decay K_L -> mu^+ mu^- gamma
In the region of large mu^+ mu^- invariant mass, the decay spectrum of K_L ->
mu^+ mu^- gamma deviates from the Dalitz pair spectrum, as a result of
interference between conversion (K_L -> gamma^* gamma -> mu^+ mu^- gamma) and
bremsstrahlung amplitudes. The latter is proportional to the K_L -> mu^+ mu^-
matrix element, whose 2 gamma-absorptive part appears to dominate the observed
K_L -> mu^+ mu^- decay rate. We examine the extent to which a scrutiny of the
K_L -> mu^+ mu^- gamma spectrum in the end-point region could provide evidence
on the real part of the K_L -> mu^+ mu^- amplitude. As a by-product, we obtain
the absorptive part of the K_L -> gamma^* gamma form factor, using data on the
K_L -> pi^+ pi^- gamma spectrum.Comment: 7 pages, 4 figure
Understanding the Forward Muon Deficit in Coherent Pion Production
For any inelastic process with ,
the cross section at is given by Adler's PCAC theorem.
Inclusion of the lepton mass has a dynamical effect (``PCAC-screening'') caused
by interference of spin-zero () and spin-one exchanges. This effect may
be relevant to the forward suppression reported in recent experiments.Comment: 3 pages, 2 figures, presented at NuInt07, Fermilab, may 31 - june 3
200
Seroprevalence of anti HCV antibodies among blood donors: a retrospective study from Haryana, India
Background: HCV is known for its chronicity and leads to cirrhosis in about 10 to 20 per cent of patients and may further progress to hepatocellular carcinoma (HCC). The global seroprevalence of HCV among blood donors varies from 0.4 to 19.2 per cent and the estimated risk for HCV transmission is between 0.10 to 2.33 per million units transfused. ELISA is the most commonly used initial assay for detecting HCV antibodies. The purpose of the present analysis was to monitor the seroprevalence of anti-HCV antibodies in the blood donor population in a hospital based blood bank in north India for a period of 10 years (2007-2016), and to evaluate the trends over the years.Methods: The purpose of the present analysis was to monitor the seroprevalence of anti-HCV antibodies in the blood donor population in a hospital based blood bank in north India for a period of 10 years (2007-2016), and to evaluate the trends over the years.Results: Of the total 340078, 298421 (87.75%) collections were voluntary and 41657 (12.25%) were replacement collections. A prevalence of 0.72% of hepatitis C virus infection was seen among the donors from the period 2007-2016. The trend of hepatitis C prevalence among donors has been fluctuating while ranging from 0.51% to 0.89%.Conclusions: For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors. Since, no vaccine is presently available for immunization against HCV infection, transfusion transmitted HCV infection remains a potential threat to the safety of the blood supply
A retrospective analysis of trends of HIV and syphilis among blood donors in north India
Background: In India, it is mandatory to screen blood donors for HIV, hepatitis B, hepatitis C, syphilis and malaria. The donor screening strategies include taking the elaborate medical history, performing preliminary clinical examination and screening for infectious markers. The infectious markers include anti-HIV (1 and 2) antibodies, hepatitis B surface antigen (HBsAg), anti-hepatitis C virus antibodies, and malaria antigens, such as histidine rich protein (HRP) and pan-aldolase. National adult (15-49 years) HIV prevalence is estimated at 0.26% (0.22%-0.32%) in 20155 (0.30% among males and 0.22% among females). The objective of this study was to be carried out with the aim to find out the seroprevalence of HIV infection and its trend among the blood donors a hospital based blood transfusion service set up in north India over a period of six years.Methods: It was record based retrospective study from 2010 to 2015. Before donation "blood donation form" had been filled by every donor and this form had particulars about age, gender, address, and occupation, date of previous donation, any illness and medical treatment taken. The donor blood samples were collected at the time of blood donation from the primary bag and tested for the presence of HIV using enzyme linked immunosorbent assay (ELISA). All donors were subjected to a pre-test counselling which was done by qualified staff trained to screen donors for blood donation.Results: A prevalence of 0.21% of HIV was seen among the donors from the period 2010-2015. The trend of HIV prevalence among donors has been fluctuating while ranging from 0.13% to 0.34%.Conclusions: HIV remains the major threat for transfusion transmitted infections in India. For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors
Patterns of voluntary and replacement blood donors in a tertiary care center: a retrospective study
Background: Blood donor base is the foundation of any blood transfusion system. In India any able-bodied individual between the age of 18 and 60 years can donate blood. Blood donors are of two types: voluntary donors and replacement donors. Blood donation should be done by low risk population otherwise there is high risk of transfusion transmissible infections like HIV, hepatitis B, hepatitis C and malaria. The present study was conceived to see the patterns of blood donation among voluntary and replacement blood donors in tertiary care centre.Methods: In this study 50 (27 male and 23 female) adult skulls were investigated to determine the type of asterion, its distance from important bony landmarks and also the nearby venous sinuses were measured.Results: Of the total 340078, 298421(87.75%) collections were voluntary and 41657(12.25%) were replacement collections. A total of 2810 camps were held to gather blood through voluntary donors. Number of blood camps held show an increasing pattern as we progress in time. Also, the trends in voluntary blood donations increased over the period and more donors donated blood whereas replacement donors decreased over the period and eventually vanished in time.Conclusions: For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors
Glueball Spin
The spin of a glueball is usually taken as coming from the spin (and possibly
the orbital angular momentum) of its constituent gluons. In light of the
difficulties in accounting for the spin of the proton from its constituent
quarks, the spin of glueballs is reexamined. The starting point is the
fundamental QCD field angular momentum operator written in terms of the
chromoelectric and chromomagnetic fields. First, we look at the restrictions
placed on the structure of glueballs from the requirement that the QCD field
angular momentum operator should satisfy the standard commutation
relationships. This can be compared to the electromagnetic charge/monopole
system, where the quantization of the field angular momentum places
restrictions (i.e. the Dirac condition) on the system. Second, we look at the
expectation value of this operator under some simplifying assumptions.Comment: 11 pages, 0 figures; added references and some discussio
Hepatitis B sero-prevalence among blood donors in Haryana: a retrospective record based study
Background: In India, it is mandatory to screen blood donors for HIV, hepatitis B, hepatitis C, syphilis and malaria. Hepatitis B is a major public health problem worldwide. Approximately 30% of the world’s population or about 2 billion persons have serological evidence of either current or past infection with hepatitis B virus. The prevalence of chronic HBV infection in India ranges from 2% to 10% as shown by different studies. India therefore comes under the intermediate to high endemicity category. The objective of this study was to carry out with the aim to find out the sero-prevalence of hepatitis B infection and its trend among the blood donors a hospital based blood transfusion service set up in north India over a period of seven years.Methods: It was record based retrospective study from 2007 to 2013. Before donation "Blood Donation Form" had been filled by every donor and this form had particulars about age, gender, address, and occupation, date of previous donation, any illness and medical treatment taken. The donor blood samples were collected at the time of blood donation from the primary bag and HbsAg screening was done using rapid test kit based on the principle of a one-step immunoassay. Samples showing repeat test reactivity on both methods were considered positive and were included for calculation of seroprevalence.Results: A prevalence of 01.13% of hepatitis B infection was seen among the donors from the period 2007-2013. The trend of hepatitis B prevalence among donors has been fluctuating while ranging from 0.94% to 1.63%.Conclusions: Reduction in seroprevalence among voluntary donors requires an effective donor education and high quality selection programme especially during big blood donation camps. For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors
CMB Lensing Power Spectrum Biases from Galaxies and Clusters using High-angular Resolution Temperature Maps
The lensing power spectrum from cosmic microwave background (CMB) temperature
maps will be measured with unprecedented precision with upcoming experiments,
including upgrades to ACT and SPT. Achieving significant improvements in
cosmological parameter constraints, such as percent level errors on sigma_8 and
an uncertainty on the total neutrino mass of approximately 50 meV, requires
percent level measurements of the CMB lensing power. This necessitates tight
control of systematic biases. We study several types of biases to the
temperature-based lensing reconstruction signal from foreground sources such as
radio and infrared galaxies and the thermal Sunyaev-Zel'dovich effect from
galaxy clusters. These foregrounds bias the CMB lensing signal due to their
non-Gaussian nature. Using simulations as well as some analytical models we
find that these sources can substantially impact the measured signal if left
untreated. However, these biases can be brought to the percent level if one
masks galaxies with fluxes at 150 GHz above 1 mJy and galaxy clusters with
masses above M_vir = 10^14 M_sun. To achieve such percent level bias, we find
that only modes up to a maximum multipole of l_max ~ 2500 should be included in
the lensing reconstruction. We also discuss ways to minimize additional bias
induced by such aggressive foreground masking by, for example, exploring a
two-step masking and in-painting algorithm.Comment: 14 pages, 14 figures, to be submitted to Ap
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