Progressing the science of effluent treatment using Lasersizer diffraction analysis - a pilot study

Disinfection of waste water with ultraviolet (UV) light is a common procedure in many sewage treatment plants because it is used to inactivate coliform bacteria in the effluent. The number of coliform bacteria in a given sample is used as a proxy to indicate the presence of targeted pathogenic organisms. Typically the coliform bacteria exist in a particle-associated state which results in their being shielded from the UV light (Darby et al., 1999). Such particles are documented in the size range 20 to 80 μm, and therefore measurement of the size distribution in a sample could be used to indicate the degree of shielding. UV treatment is less effective for particles larger than about 40 μm in size (Table 1). Our pilot study used the laser diffraction technique to generate particle-size distributions of samples of effluent. By quantifying the amount of bacteria-shielding particles using this technique we were able to estimate the general efficacy of the UV sterilization process. The surface weighted mean diameter statistic was taken as a numerical measure of the bacteriashielding particle size distribution

Importance of Baseline Prognostic Factors With Increasing Time Since Initiation of Highly Active Antiretroviral Therapy: Collaborative Analysis of Cohorts of HIV-1-Infected Patients

Background: The extent to which the prognosis for AIDS and death of patients initiating highly active antiretroviral therapy (HAART) continues to be affected by their characteristics at the time of initiation (baseline) is unclear. Methods: We analyzed data on 20,379 treatment-naive HIV-1- infected adults who started HAART in 1 of 12 cohort studies in Europe and North America (61,798 person-years of follow-up, 1844 AIDS events, and 1005 deaths). Results: Although baseline CD4 cell count became less prognostic with time, individuals with a baseline CD4 count 350 cells/μL (hazard ratio for AIDS = 2.3, 95% confidence interval [CI]: 1.0 to 2.3; mortality hazard ratio = 2.5, 95% CI: 1.2 to 5.5, 4 to 6 years after starting HAART). Rates of AIDS were persistently higher in individuals who had experienced an AIDS event before starting HAART. Individuals with presumed transmission by means of injection drug use experienced substantially higher rates of AIDS and death than other individuals throughout follow-up (AIDS hazard ratio = 1.6, 95% CI: 0.8 to 3.0; mortality hazard ratio = 3.5, 95% CI: 2.2 to 5.5, 4 to 6 years after starting HAART). Conclusions: Compared with other patient groups, injection drug users and patients with advanced immunodeficiency at baseline experience substantially increased rates of AIDS and death up to 6 years after starting HAART