Multiple-scattering effect on ozone retrieval from space-based differential absorption lidar measurements.

Single-scattering and multiple-scattering lidar signals are calculated for a spaceborne differential absorption lidar system for global ozone measurements at the on and off wavelength pair at 305 and 315 nm. The effect of multiple scattering is found to be negligible on stratospheric and tropospheric ozone retrieval under background stratospheric aerosol. Under low-visibility conditions in the planetary boundary layer the presence of multiple scattering causes an overestimation in maritime aerosol and an underestimation in urban as well as in rural aerosol. This effect is also examined in three cirrus models. The multiple scattering does not permit accurate ozone retrieval within cirrus; however, below it the solution recovers somewhat with generally an underestimation depending on the type and density of cirrus. The effect of aerosol and Rayleigh extinction on the ozone retrieval is also discussed.

Inhibition of hepatic extramedullary haemopoiesis by nucleoprotein of heterologous rotavirus strain in infant mice.

Infant mice (NMRI strain) showed the inhibition of hepatic extramedullary haemopoiesis by oral inoculation of a 100 ID50 dose of EB rotavirus and nucleoprotein of SA-11 rotavirus (serotype 3). The extramedullary haemopoiesis was observed by oral inoculation of surface protein VP7 of SA-11 rotavirus and in control (placebo administered) mice.

An epidemic of encephalitis in Haryana: serological evidence of Japanese encephalitis in a few patients.

An epidemic of encephalitis occurred in the eastern, paddy growing districts of Haryana state between July and November 1990. One hundred and eighty-two patients with encephalitis were admitted to different hospitals in Haryana and 118 of them expired (mortality rate 64.8%); 88% of the patients were children. The male to female ratio was 2. 3. 1. IgM class of antibodies to Japanese Encephalitis (JE) Virus could be demonstrated in the CSF and/or sera of 3 surviving and 2 fatal patients of the 19 patients studied. This is the first detailed report on an epidemic of encephalitis in North-Western part of India. Serologically proven cases of JE are being reported, for the first time, from this region.

Automated method for lidar determination of cloud-base height and vertical extent.

An algorithm for the automated analysis of lidar cloud returns has been developed as part of the Experimental Cloud Lidar Pilot Study program. This automated method determines the cloud-base and cloud-top heights as well as the altitude of the maximum return signal. A large body of cloud data that were obtained at 532 and 1064 nm with a Nd:YAG lidar have been evaluated and it has been found that the algorithm can handle the wide range of complex cloud situations encountered. The need for a more careful definition of the cloud-base height and cloud-top height is described and discussed in relation to the existing measurements with rotating beam and laser ceilometers.

Etiological spectrum of acute sporadic viral hepatitis amongst adults in Chandigarh.

All 77 HBsAg positive and 94 of representative HBsAg negative sera derived from 253 adult patients with acute sporadic viral hepatitis during 1987 at Chandigarh were tested for serological markers of hepatitis B virus (HBV) and hepatitis A virus (HAV) infections. The HBsAg positive patients could be classified as acute hepatitis B (64%); chronic hepatitis B with exacerbation, or liver damage by other infectious or noninfectious agent/s over a chronic HBsAg carrier state (35%); and coinfection of HBV and HAV (1%). Among the HBsAg negative hepatitis group, acute hepatitis B was diagnosed in 4 per cent of patients and acute hepatitis A in another 4 per cent.

Delta virus infections in and around Chandigarh, northern India: evidence for endemicity.

Delta virus infections, so far, have not been documented from India. Here we report for the first time the endemicity of delta virus infection in this geographical area. HBsAg positive serum samples from 81 patients and 10 healthy voluntary blood donors were tested for delta antigen. Seven out of 49 (14.3%) sporadic acute hepatitis cases, 3 out of 8 (37.5%) chronic renal failure patients requiring frequent haemodialysis, 1 out of 22 (4.6%) chronic liver disease cases and 1 out of 10 (10%) apparently healthy voluntary blood donors had delta antigenaemia.

Standardization and demonstration of antibody-coated Candida in urine by direct immunofluorescence test.

Acetone, carbontetrachloride, ethyl alcohol, mixture of ethyl alcohol and acetone, and heat were assessed for fixative property for direct immunofluorescent (IF) staining of antibody-coated Candida cells. The results indicated that ethyl alcohol was the most suitable fixative for the test. Antisera containing 16 units of Candida albicans type A agglutinin were found essential to get optimal detectable fluorescence of antibody-coated yeast cells. IF test showed cross reactivity between the yeasts of C. albicans and C. tropicalis. However, there was no cross reactivity with the conidia of A. flavus. The direct IF test could demonstrate antibody-coated yeast cells and pseudomycelia in deposits of urine in the direct smear. It correlated well with microscopy and culture studies. At times, it could demonstrate the antibody-coated yeasts earlier than routine significant culture. It could also differentiate the significant from non-significant fungal isolates from urine.

Determination of cloud microphysical properties by laser backscattering and extinction measurements.

The extinction and backscattering of 514-nm laser radiation in polydisperse water droplet clouds have been studied in the laboratory. Three cloud size distributions with modal diameters of 0.02, 5, and 12 microm have been investigated. The relationships between the cloud optical parameters (attenuation coefficient sigma and volume backscattering coefficient beta(pi)) and the cloud water content C have been measured for each size distribution. It has been found that a linear relationship exists between sigma and C and between beta(pi) and C for cloud water content values up to 3 g/m3. The linear relationships obtained, however, have slopes which depend on the droplet size distribution. For a given water content both sigma and beta(pi) increase as the modal diameter decreases. The measured data are compared with existing theoretical analyses and discussed in terms of their application to lidar measurements of atmospheric clouds. It is concluded that the empirical information obtained can serve as a basis for quantitative lidar measurements.

Enterovirus 70 acute hemorrhagic conjunctivitis--sporadic cases.

Acute hemorrhagic conjunctivitis (AHC) has been reported in epidemics. This is a report of 29 sporadic cases of AHC recorded over a period of two years after the 1981 epidemic in and around Chandigarh. A rapid and simple immunofluorescence test was developed and standardized in our Institute for the diagnosis of AHC. It was used for epidemiological monitoring of cases and to establish the diagnosis in suspected cases of AHC reporting after the epidemic. The clinical picture of epidemic and sporadic cases is compared.

Immunofluorescence test for the epidemiological monitoring of acute haemorrhagic conjunctivitis cases.

An epidemic of acute haemorrhagic conjunctivitis (AHC) occurred in and around Chandigarh, north India, during June, July and August 1981. Considering the difficulty of virus isolation, the indirect immunofluorescence test was used for the demonstration of virus-specific antigen in the cytoplasm of exfoliated conjunctival cells, using reference antisera. The epidemic appeared to be primarily due to enterovirus type 70. The method was found suitable for the rapid diagnosis of AHC cases and for detecting subclinical infection among healthy subjects and convalescent carriers. During follow-up, it was observed that some of the AHC cases were shedding virus-infected conjunctival cells for a prolonged period, even after clinical recovery and during convalescence, before they became free from virus. In the absence of virus isolation, this method can be considered as suitable for the epidemiological monitoring of AHC.

Rapid immunofluorescence diagnosis of acute hemorrhagic conjunctivitis caused by enterovirus 70.

During 1981-1982, epidemics of acute hemorrhagic conjunctivitis (AHC) occurred in and around Chandigarh, India. Conjunctival swabs were taken from AHC cases and investigated by the indirect immunofluorescence method both in Chandigarh and in Houston. By using reference antiserum, both laboratories proved enterovirus type 70 to be the causative agent of the epidemics. The immunofluorescence test was evaluated as a rapid method for the diagnosis of AHC.