Phase dynamics of InAs/GaAs quantum dot semiconductor optical amplifiers

The gain and phase dynamics of InAs/GaAs quantum dot amplifiers are studied using single and two-color heterodyne pump probe spectroscopy. The relaxation of the wetting layer carrier density is shown to have a strong effect on the phase dynamics of both ground and excited state transients, while having a much weaker effect on the gain dynamics. In addition, the dynamical alpha factor may also display a constant value after an initial transient. Such behavior is strongly encouraging for reduced pattern effect operation in high speed optical networks. (c) 2007 American Institute of Physics.(DOI: 10.1063/1.2823589

Comparison of indoor contact time data in Zambia and Western Cape, South Africa suggests targeting of interventions to reduce Mycobacterium tuberculosis transmission should be informed by local data.

BACKGROUND: In high incidence settings, the majority of Mycobacterium tuberculosis (M.tb) transmission occurs outside the household. Little is known about where people's indoor contacts occur outside the household, and how this differs between different settings. We estimate the number of contact hours that occur between adults and adult/youths and children in different building types in urban areas in Western Cape, South Africa, and Zambia. METHODS: Data were collected from 3206 adults using a cross-sectional survey, on buildings visited in a 24-h period, including building function, visit duration, and number of adults/youths and children (5-12 years) present. The mean numbers of contact hours per day by building function were calculated. RESULTS: Adults in Western Cape were more likely to visit workplaces, and less likely to visit shops and churches than adults in Zambia. Adults in Western Cape spent longer per visit in other homes and workplaces than adults in Zambia. More adults/youths were present at visits to shops and churches in Western Cape than in Zambia, and fewer at homes and hairdressers. More children were present at visits to shops in Western Cape than in Zambia, and fewer at schools and hairdressers. Overall numbers of adult/youth indoor contact hours were the same at both sites (35.4 and 37.6 h in Western Cape and Zambia respectively, p = 0.4). Child contact hours were higher in Zambia (16.0 vs 13.7 h, p = 0.03). Adult/youth and child contact hours were highest in workplaces in Western Cape and churches in Zambia. Compared to Zambia, adult contact hours in Western Cape were higher in workplaces (15.2 vs 8.0 h, p = 0.004), and lower in churches (3.7 vs 8.6 h, p = 0.002). Child contact hours were higher in other peoples' homes (2.8 vs 1.6 h, p = 0.03) and workplaces (4.9 vs 2.1 h, p = 0.003), and lower in churches (2.5 vs 6.2, p = 0.004) and schools (0.4 vs 1.5, p = 0.01). CONCLUSIONS: Patterns of indoor contact between adults and adults/youths and children differ between different sites in high M.tb incidence areas. Targeting public buildings with interventions to reduce M.tb transmission (e.g. increasing ventilation or UV irradiation) should be informed by local data

Age- and Sex-Specific Social Contact Patterns and Incidence of Mycobacterium tuberculosis Infection: Interview Questionnaire

Questionnaire used in a study of Mycobacterium tuberculosis infection incidences among adults in the Western Cape, South Africa. The questionnaire was piloted in Zambia in early 2011, before being used in face-to-face interviews with random selected adults who were enrolled in the Zambia-South Africa TB and AIDS Reduction (ZAMSTAR) Study

Age- and Sex-Specific Social Contact Patterns and Incidence of Mycobacterium tuberculosis Infection.

We aimed to model the incidence of infection with Mycobacterium tuberculosis among adults using data on infection incidence in children, disease prevalence in adults, and social contact patterns. We conducted a cross-sectional face-to-face survey of adults in 2011, enumerating "close" (shared conversation) and "casual" (shared indoor space) social contacts in 16 Zambian communities and 8 South African communities. We modeled the incidence of M. tuberculosis infection in all age groups using these contact patterns, as well as the observed incidence of M. tuberculosis infection in children and the prevalence of tuberculosis disease in adults. A total of 3,528 adults participated in the study. The reported rates of close and casual contact were 4.9 per adult per day (95% confidence interval: 4.6, 5.2) and 10.4 per adult per day (95% confidence interval: 9.3, 11.6), respectively. Rates of close contact were higher for adults in larger households and rural areas. There was preferential mixing of close contacts within age groups and within sexes. The estimated incidence of M. tuberculosis infection in adults was 1.5-6 times higher (2.5%-10% per year) than that in children. More than 50% of infections in men, women, and children were estimated to be due to contact with adult men. We conclude that estimates of infection incidence based on surveys in children might underestimate incidence in adults. Most infections may be due to contact with adult men. Treatment and control of tuberculosis in men is critical to protecting men, women, and children from tuberculosis

Increased Oxidative Burden Associated with Traffic Component of Ambient Particulate Matter at Roadside and Urban Background Schools Sites in London

As the incidence of respiratory and allergic symptoms has been reported to be increased in children attending schools in close proximity to busy roads, it was hypothesised that PM from roadside schools would display enhanced oxidative potential (OP). Two consecutive one-week air quality monitoring campaigns were conducted at seven school sampling sites, reflecting roadside and urban background in London. Chemical characteristics of size fractionated particulate matter (PM) samples were related to the capacity to drive biological oxidation reactions in a synthetic respiratory tract lining fluid. Contrary to hypothesised contrasts in particulate OP between school site types, no robust size-fractionated differences in OP were identified due high temporal variability in concentrations of PM components over the one-week sampling campaigns. For OP assessed both by ascorbate (OPAA m−3) and glutathione (OPGSH m−3) depletion, the highest OP per cubic metre of air was in the largest size fraction, PM1.9–10.2. However, when expressed per unit mass of particles OPAA µg−1 showed no significant dependence upon particle size, while OPGSH µg−1 had a tendency to increase with increasing particle size, paralleling increased concentrations of Fe, Ba and Cu. The two OP metrics were not significantly correlated with one another, suggesting that the glutathione and ascorbate depletion assays respond to different components of the particles. Ascorbate depletion per unit mass did not show the same dependence as for GSH and it is possible that other trace metals (Zn, Ni, V) or organic components which are enriched in the finer particle fractions, or the greater surface area of smaller particles, counter-balance the redox activity of Fe, Ba and Cu in the coarse particles. Further work with longer-term sampling and a larger suite of analytes is advised in order to better elucidate the determinants of oxidative potential, and to fuller explore the contrasts between site types.\ud \u

Improving the reach of vaccines to low-resource regions, with a needle-free vaccine delivery device and long-term thermostabilization

Dry-coated microprojections can deliver vaccine to abundant antigen-presenting cells in the skin and induce efficient immune responses and the dry-coated vaccines are expected to be thermostable at elevated temperatures. In this paper, we show that we have dramatically improved our previously reported gas-jet drying coating method and greatly increased the delivery efficiency of coating from patch to skin to from 6.5% to 32.5%, by both varying the coating parameters and removing the patch edge. Combined with our previous dose sparing report of influenza vaccine delivery in a mouse model, the results show that we now achieve equivalent protective immune responses as intramuscular injection (with the needle and syringe), but with only 1/30th of the actual dose. We also show that influenza vaccine coated microprojection patches are stable for at least 6 months at 23 degrees C. inducing comparable immunogenicity with freshly coated patches. The dry-coated microprojection patches thus have key and unique attributes in ultimately meeting the medical need in certain low-resource regions with low vaccine affordability and difficulty in maintaining "cold-chain" for vaccine storage and transport. (C) 2011 Elsevier B.V. All rights reserved

WDM transmission at 2μm over low-loss hollow core photonic bandgap fiber

World's first demonstration of WDM transmission in a HC-PBGF at the predicted low loss region of 2m is presented. A total capacity of 16 Gbit/s is achieved using 1×8.5 Gbit/s and 3×2.5 Gbit/s channels modulated using NRZ OOK over 290 meters of hollow core fiber

Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits

We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations refined the transit ephemerides of K2-3 b, c, and d by over a factor of 10. We analyze ground-based photometry from the Evryscope and Fairborn Observatory to determine the characteristic stellar activity timescales for our Gaussian Process fit, including the stellar rotation period and activity region decay timescale. The stellar rotation signals for both stars are evident in the radial velocity data and is included in our fit using a Gaussian process trained on the photometry. We find the masses of K2-3 b, K2-3 c, and GJ3470 b to be 6.48{}-0.93+0.99, 2.14{}-1.04+1.08, and 12.58{}-1.28+1.31 M ⊕, respectively. K2-3 d was not significantly detected and has a 3σ upper limit of 2.80 M ⊕. These two systems are training cases for future TESS systems; due to the low planet densities (ρ < 3.7 g cm-3) and bright host stars (K < 9 mag), they are among the best candidates for transmission spectroscopy in order to characterize the atmospheric compositions of small planets

Skin Vaccination against Cervical Cancer Associated Human Papillomavirus with a Novel Micro-Projection Array in a Mouse Model

Background: Better delivery systems are needed for routinely used vaccines, to improve vaccine uptake. Many vaccines contain alum or alum based adjuvants. Here we investigate a novel dry-coated densely-packed micro-projection array skin patch (Nanopatch (TM)) as an alternate delivery system to intramuscular injection for delivering an alum adjuvanted human papillomavirus (HPV) vaccine (Gardasil (R)) commonly used as a prophylactic vaccine against cervical cancer