9 research outputs found
The Third Data Release of the Sloan Digital Sky Survey
This paper describes the Third Data Release of the Sloan Digital Sky Survey
(SDSS). This release, containing data taken up through June 2003, includes
imaging data in five bands over 5282 deg^2, photometric and astrometric
catalogs of the 141 million objects detected in these imaging data, and spectra
of 528,640 objects selected over 4188 deg^2. The pipelines analyzing both
images and spectroscopy are unchanged from those used in our Second Data
Release.Comment: 14 pages, including 2 postscript figures. Submitted to AJ. Data
available at http://www.sdss.org/dr
SDSS DR7 white dwarf catalog
We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20,407 white dwarf spectra, representing 19,712 stars, and provide atmospheric model fits to 14,120 DA and 1011 DB white dwarf spectra from 12,843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated log g if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs
Sugar and phosphate metabolism and alkaloid production phases in submerged cultures of two Claviceps strains
Hepatitis B and C infection in haemodialysis patients in Libya: prevalence, incidence and risk factors
Background: Patients receiving maintenance haemodialysis (HD) are at higher risk for acquiring Hepatitis B Virus
(HBV) and Hepatitis C Virus (HCV) infections than the general population. Strict infection control measures are
essential to prevent nosocomial transmission. We aimed to investigate the incidence and prevalence of HBV and
HCV infection in the HD population of Libya as well as risk factors for infection.
Methods: All adult patients receiving maintenance HD (n=2382) in Libyan dialysis centres (n=39) were studied
between May 2009 and October 2010. Testing for Hepatitis B surface antigen (HBsAg) and anti-HCV antibodies was
performed at initiation of dialysis and every 3–6 months thereafter. Patients who were sero-negative for HBV and
HCV (n=1160) were followed up for 1 year to detect sero-conversions.
Results: Participant median age was 49 years and 58% were male. 831 patients (34.9%) were sero-positive for HBV
and/or HCV (anti-HCV positive 31.1%; HBsAg positive 2.6%; both positive 1.2%). Of the sero-positive patients
4.7% were known to be infected before the initiation of HD. The prevalence of HBV±HCV infection varied widely
between HD centres from 0% to 75.9%. Sero-positive patients were younger, had longer time on dialysis and more
previous blood transfusions. Prospective follow-up revealed an incidence of sero-conversion of 7.7% during 1 year
(7.1% HCV; 0.6% HBV). Wide variation in rates of newly acquired infections was observed between dialysis centres.
All new HBV cases were referred from centres already treating HBV infected patients. New HCV infections were
reported in most centres but the rate of HCV sero-conversion varied widely from 1.5% to 31%. Duration of dialysis,
history of previous renal transplant and history of receiving HD in another centre in Libya were significantly
associated with sero-conversion.
Conclusion: Patients on maintenance HD in Libya have a high incidence and prevalence of HCV infection and
lower rates of HBV infection. The factors associated with HBV and HCV infection are highly suggestive of
nosocomial transmission within HD units. Urgent action is required to improve infection control measures in HD
centres and to reduce dependence on blood transfusions for the treatment of anaemia.
Keywords: Haemodialysis, Hepatitis B, Hepatitis C, Incidence, Libya, Nosocomial infection, Prevalenc