187 research outputs found
Use of sentinel snails for the detection of Schistosoma haematobium transmission on Zanzibar and observations on transmission patterns
No full textUrogenital schistosomiasis is an important public health issue in Zanzibar. Transmission of the parasite to the human population is related to the distribution of the intermediate snail host, Bulinus globosus. We measured B. globosus abundance and Schistosoma haematobium prevalence within snails in a series of naturally occurring populations and compared prevalence detected by observing cercarial shedding for patent infections, and by PCR using DraI repeat. A total of 2146 B. globosus were collected throughout the study period from 2003 to 2007; of these 85 (3.96%) were shedding cercariae. The levels of infection detected by PCR were consistently higher (40-100 percent). Levels of exposure to miracidia in the field were measured using sentinel snails. B. globosus (a susceptible host) and B. nasutus (a non-susceptible host) were placed in cages at transmission sites for 72h to observe rates of penetration by miracidia. Both B. globosus and B. nasutus tested positive for S. haematobium by PCR (up to 24% infected) indicating frequent contamination of the waterbodies with S. haematobium miracidia. The use of sentinel snails coupled with PCR diagnostics could be a sensitive tool for mapping and monitoring transmission of schistosomiasis in areas of low prevalence
Mid-infrared photonic crystal waveguides in SOI
No full textWe demonstrate the design, fabrication and characterization of mid-infrared photonic crystal waveguides on a silicon-on-insulator platform, showing guided modes in the wavelength regime between 2.9 and 3.9 μm.</p
HTLV-I and Strongyloides in Australia: The worm lurking beneath
No full textStrongyloidiasis and HTLV-I (human T-lymphotropic virus-1) are important infections that are endemic in many countries around the world with an estimated 370 million infected with Strongyloides stercoralis alone, and 5–10 million with HTVL-I. Co-infections with these pathogens are associated with significant morbidity and can be fatal. HTLV-I infects T-cells thus causing dysregulation of the immune system which has been linked to dissemination and hyperinfection of S. stercoralis leading to bacterial sepsis which can result in death. Both of these pathogens are endemic in Australia primarily in remote communities in Queensland, the Northern Territory, and Western Australia. Other cases in Australia have occurred in immigrants and refugees, returned travellers, and Australian Defence Force personnel. HTLV-I infection is lifelong with no known cure. Strongyloidiasis is a long-term chronic disease that can remain latent for decades, as shown by infections diagnosed in prisoners of war from World War II and the Vietnam War testing positive decades after they returned from these conflicts. This review aims to shed light on concomitant infections of HTLV-I with S. stercoralis primarily in Australia but in the global context as well
Development of continuous-wave pump-enhanced optical parametric oscillators and their application to photo-thermal spectroscopy
No full textThe development of both a spectrally tunable radiation source and a sensitive detection transducer for spectroscopic applications are described in this thesis. The emission source is an optical parametric oscillator operating in the continuous-wave regime with a pump-enhanced singly-resonant architecture and involves the separate development of two constituent parts: A continuous-wave pump laser operating at 1064 nm based on neodymium-doped crystals focused on achieving high power whilst maintaining single-frequency operation; and a split-ring pump-enhanced optical parametric oscillator operating from this pump source focused on fine-tuning in mode-hops. This source was capable of coarsely tuning in the mid-infrared over 3 – 4 μm with an average of 140 mW of power with the ability of automated mode-hop tuning continuously over 90 cm⁻¹ in 0.07 cm⁻¹ steps. The detection transducer is based upon photo-thermal interferometric spectroscopy which employs a phase-sensitive method to detect the heating of a gas sample under radiation from the appropriately tuned source. Utilisation of a spectrally-independent probe beam permits samples with strong absorption features in the mid/deep-infrared to be examined whilst utilising the low-cost, high-sensitivity photodetectors in the visible/near-infrared region. This work implements both a Mach-Zehnder and a Sagnac interferometer, where the latter holds the potential to minimise the effects of the environment and simplify the associated experimental steps by removing stabilising electronic circuitry. Combined utilisation of this transducer alongside the excitation source has demonstrated an ability to detect the presence of ethane down to 100 parts-per-billion. Further development considered the interferometer inherent in photo-thermal spectroscopy, where this provides an avenue for employing optical squeezing techniques to increase the ultimate sensitivity of this technique. Construction of a squeezed light generator to use as a probe beam based on second-order nonlinearity has additionally been attempted in this work and has been shown to exhibit anti-squeezing characteristic behaviour."This work was supported by the EPSRC in association with the Centre for Doctoral Training in
Applied Photonics [grant number: EP/L01596X/1]; and Fraunhofer UK." -- Fundin
Study and implementation of urogenital schistosomiasis elimination in Zanzibar (Unguja and Pemba islands) using an integrated multidisciplinary approach
No full textABSTRACT: BACKGROUND: Schistosomiasis is a parasitic infection that continues to be a major public health problem in many developing countries being responsible for an estimated burden of at least 1.4 million disability-adjusted life years (DALYs) in Africa alone. However, morbidity due to schistosomiasis has been greatly reduced in some parts of the world, including Zanzibar. The Zanzibar government is now committed to eliminate urogenital schistosomiasis. Over the next 3--5 years, the whole at-risk population will be administered praziquantel (40 mg/kg) biannually. Additionally, snail control and behaviour change interventions will be implemented in selected communities and the impact measured in a randomized intervention trial. METHODS: In this 5-year research study, on both Unguja and Pemba islands, urogenital schistosomiasis will be assessed in 45 communities with urine filtration and reagent strips in 4,500 schoolchildren aged 9--12 years annually, and in 4,500 first-year schoolchildren and 2,250 adults in years 1 and 5. Additionally, from first-year schoolchildren, a finger-prick blood sample will be collected and examined for Schistosoma haematobium infection biomarkers. Changes in prevalence and infection intensity will be assessed annually. Among the 45 communities, 15 were randomized for biannual snail control with niclosamide, in concordance with preventive chemotherapy campaigns. The reduction of Bulinus globosus snail populations and S. haematobium-infected snails will be investigated. In 15 other communities, interventions triggering behaviour change have been designed and will be implemented in collaboration with the community. A change in knowledge, attitudes and practices will be assessed annually through focus group discussions and in-depth interviews with schoolchildren, teachers, parents and community leaders. In all 45 communities, changes in the health system, water and sanitation infrastructure will be annually tracked by standardized questionnaire-interviews with community leaders. Additional issues potentially impacting on study outcomes and all incurring costs will be monitored and recorded. DISCUSSION: Elimination of schistosomiasis has become a priority on the agenda of the Zanzibar government and the international community. Our study will contribute to identifying what, in addition to preventive chemotherapy, needs to be done to prevent, control, and ultimately eliminate schistosomiasis, and to draw lessons for current and future schistosomiasis elimination programmes in Africa and elsewhere.Trial registrationISRCTN4883768
A critique of the technical and structural flaws in the legal aid scheme: and an analysis of the proposals for reform contained in the legal aid act 1988
No full textThe critique of the Legal Aid scheme is on two levels. Firstly ‘technical’ problems are discussed. It is in the nature of these problems that they can be resolved within the present structural arrangement of the scheme. The administrative procedures, use and coverage of the scheme are examined, taking into account the view point of the consumer. Privately paying and legal aid clients are compared in terms of the quality of the service they receive, solicitors’ attitudes to them, and the differing nature of the problems of poor people. The argument then concentrates on the 'structural’ defects of the scheme, avoiding the minutiae of its workings. The proprietry of a scheme created to provide legal services to poor people through solicitors in private practice is questioned. The legally orientated theory underlying the Legal Aid scheme is contrasted to social and consumer based theories, and to the practical model of the American Neighbourhood Law Firm. Empirical research is used to highlight the deficiency in the distribution of private practice solicitors to meet the needs of the poor; and the compensatory role of advice agencies in providing the relevant legal services to them. The Legal Aid Act 1988 is subjected to a close analysis with particular emphasis on the Lord Chancellor's powers, and the creation of the Legal Aid Board. The role and agenda of the Board, and future of the Legal Aid scheme are considered by outlining and examining the proposals contained in the preceding White Paper. Conclusions are drawn as to the possible results of the Act, and its value in relation to the previous critique of the Legal Aid scheme
An intracavity optical parametric oscillator with very high repetition rate and broad tunability based upon room temperature periodically-poled MgO:LiNbO3 with fanned grating design
No full textWe report a low-pump-threshold, very high-repetition-rate, singly resonant optical parametric oscillator (OPO) pumped internally to a diode-pumped, Q-switched Nd : YVO4 laser. The OPO, based upon a 27.0-32.5-mu m periodically poled MgO : LiNbO3 crystal with fan grating design, exhibits a broad tunability range of 1.38-1.79 mu m (Delta lambda(s) = 411 nm) and 2.62-4.64 mu m (Delta lambda(i) = 2019 nm) in the signal and idler fields, respectively. For an external diode pump power of only 3 W, up to 150 mW of idler were extracted from the device or, when the signal field was output coupled, 330 and 100 mW of signal and idler, respectively, were simultaneously obtained. By taking advantage of the intracavity parametric cavity dumping process, repetition rates in excess of 350 kHz were achieved whilst maintaining high down-conversion efficiency. We demonstrate the potential of this device in spectroscopic applications with an absorption measurement of low concentration CH4 .</p
Mid-infrared photonic crystal waveguides in silicon
No full textWe demonstrate the design, fabrication and characterization of mid-infrared photonic crystal waveguides on a silicon-on-insulator platform, showing guided modes in the wavelength regime between 2.9 and 3.9 µm. The characterization is performed with a proprietary intra-cavity Optical Parametric Oscillator in a free space optical setup and with a fibre coupled setup using a commercial Quantum Cascade Laser. We discuss the use of an integrated Mach-Zehnder interferometer for dispersion measurements and report a measured group velocity of up to a value of ng = 12, and determine the propagation loss to be 20 dB/cm.<br/
Epidemiological interactions between urogenital and intestinal human schistosomiasis in the context of praziquantel treatment across three West African countries
No full text© 2015 Knowles et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
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