Self-consistent theory of random lasing in the time-domain

Random lasers are unique systems where lasing occurs due to repetitive scattering in a disordered nanostructure. Previous descriptions of random lasing are numerous, however a full time-dependent theory that describes the introduction of gain directly from first principles is lacking in the literature. This letter will present an analytic self-consistent time-dependent theory of random lasing that contains the results from the well-known steady-state ab-initio laser theory. This theory can also describe a number of temporal phenomena that have been observed in previous experiments and facilitates the incorporation of these devices into their envisioned practical applications.Comment: 12 page

Sales in India: An Econometric Regression Analysis

India has a labor force of almost 500 million, yet has an unemployment rate of approximately 8.8%. Forty-five million people are unemployed; therefore, making it important to examine what makes a company profitable. Using data provided by an Enterprise Survey questionnaire given to firms in 2006, I evaluate what effects the volume of sales on a firm level. Using SPSS, a theoretical model was tested and then modified to eliminate problems such as heteroskedasticity, multicollinearity, and serial correlation. I find that years in business and access to security have a positive, statistically significant impact on sales, while the firm being located in the owner\u27s house has a negative, statistically significant impact on sales. I argue that the biggest ways to increase sales would be to register the firm with the government, increase employee compensation, and ensure that the firm will have some form of security to protect its assets. If Indian firms are able to become more profitable, the unemployment rate will decrease over time

Risk Factors for High Early Mortality in Patients on Antiretroviral Treatment in a Rural District of Malawi.

OBJECTIVES: Among adults started on antiretroviral treatment (ART) in a rural district hospital (a) to determine the cumulative proportion of deaths that occur within 3 and 6 months of starting ART, and (b) to identify risk factors that may be associated with such mortality. DESIGN AND SETTING: A cross-sectional analytical study set in Thyolo district, Malawi. METHODS: Over a 2-year period (April 2003 to April 2005) mortality within the first 3 and 6 months of starting ART was determined and risk factors were examined. RESULTS: A total of 1507 individuals (517 men and 990 women), whose median age was 35 years were included in the study. There were a total of 190 (12.6%) deaths on ART of which 116 (61%) occurred within the first 3 months (very early mortality) and 150 (79%) during the first 6 months of initiating ART. Significant risk factors associated with such mortality included WHO stage IV disease, a baseline CD4 cell count under 50 cells/mul and increasing grades of malnutrition. A linear trend in mortality was observed with increasing grades of malnutrition (chi for trend = 96.1, P </= 0.001) and decreasing CD4 cell counts (chi for trend = 72.4, P </= 0.001). Individuals who were severely malnourished [body mass index (BMI) < 16.0 kg/m] had a six times higher risk of dying in the first 3 months than those with a normal nutritional status. CONCLUSIONS: Among individuals starting ART, the BMI and clinical staging could be important screening tools for use to identify and target individuals who, despite ART, are still at a high risk of early death

Novel genetic engineering technology which increases leaf lipid content modifies the ensiling properties of perennial ryegrass : a thesis presented in partial fulfillment of the requirements for the degree of Masters in Agricultural Science at Massey University, Palmerston North

A novel strategy to increase the metabolisable energy (ME) yield of pastures has been the development of a genetic engineering technology which increases the leaf lipid content and biomass production of perennial ryegrass (PRG). Outdoor plot/feeding trials of genetically engineered crops are prohibited under the current New Zealand (NZ) regulatory framework. However, this high lipid PRG may become available to farmers and eventually be used to make silage, which could fulfill an important role as a high ME, inexpensive, supplementary feed for livestock. Ensiling preserves a crop’s nutrients at a high moisture content and at a low pH, by microbial fermentation of plant sugars into lactic acid under anaerobic conditions. In a preliminary investigation into the ensiling biochemistry of this high lipid PRG, glasshouse-grown materials were wilted and inoculated, and then ensiled on a miniature scale. A series of method development ensiling experiments revealed that non-transgenic PRG grown in glasshouse conditions during the NZ spring/summer was very difficult to ensile naturally, due to its low water soluble sugar to buffering capacity ratio. In order to generate well-preserved silage in the main experiment, glucose was added (post-harvest) to a non-transgenic PRG genotype (WT) and two transgenic PRG genotypes containing ‘medium’ and ‘high’ leaf lipid levels (ML and HL). The HL plants produced 51% more dry biomass than WT during the regrowth period. Pre-ensiled HL had 31% higher fatty acid content, 70% higher nitrate content and a 17% lower water soluble sugar to crude protein ratio than WT. ML was intermediate. The glasshouse growth environment resulted in an atypical overall PRG nutritional composition. WT, ML and HL underwent a similar fermentation, and nutrients were well-preserved. The nutritional differences in the ensiled material largely reflected those in their fresh counterparts, although a longer wilt caused greater overall digestible nutrient losses in HL. In an in vitro rumen incubation experiment the fatty acids in HL silage exhibited less complete biohydrogenation than in fresh and ensiled WT. Experiments using a range of high lipid PRG lines grown in a range of environments will be needed to validate these results