Application of ERS-1 and Topex/Poseidon altimetry using precise orbits

The work described in this thesis concerns the application of radar altimetry, collected from the ERS-1 and TOPEX/POSEIDON missions, to precise satellite orbits computed at Aston University. The data is analysed in a long arc fashion to determine range biases, time tag biases, sea surface topographies and to assess the radial accuracy of the generated orbits through crossover analysis. A sea surface variability study is carried out for the North Sea using repeat altimeter profiles from ERS-1 and TOPEX/POSEIDON in order to verify two local U.K. models for ocean tide and storm surge effects. An on-side technique over the English Channel is performed to compute the ERS-1, TOPEX and POSEIDON altimeter range biases by using a combination of altimetry, precise orbits determined by short arc methods, tide gauge data, GPS measurements, geoid, ocean tide and storm surge models. The remaining part of the thesis presents some techniques for the short arc correction of long arc orbits. Validation of this model is achieved by way of comparison with actual SEASAT short arcs. Simulations are performed for the ERS-1 microwave tracking system, PRARE, using the range data to determine time dependent orbit corrections. Finally, a brief chapter is devoted to the recovery of errors in station coordinates by the use of multiple short arcs

An application of recent developments of Data Envelopment Analysis to the evaluation of secondary schools in Portugal

This paper highlights the potentialities of Data Envelopment Analysis to evaluate the performance of organisations, using the concept of super-efficiency - an extension of DEA which increases its performance - and presents an example from the public sector to illustrate the method. The example selected is that of a school network where a place in a school can be seen as a perishable good, as places which are not occupied during an academic year are wasted. Results for the Portuguese Secondary school network show that the average efficiency of overcrowded schools, that is, those exceeding their capacity, is lower than that of schools which are less crowded. This shows clearly that overcrowded schools, on average, are less efficient in transforming their inputs into academic performance. It is this conviction, seldom proved scientifically, which leads governments and international organisations to recommend planning criteria for public facilities

Short-term effects of a gain-focused reappraisal intervention for dementia caregivers: A double-blind cluster-randomized controlled trial

Objectives To examine the effects of a benefit-finding intervention, the key feature being the use of gain-focused reappraisal strategies to find positive meanings and benefits in caring for someone with dementia. Design: Cluster-randomized double-blind controlled trial. Setting: Social centers and clinics. Participants: 129 caregivers. Inclusion criteria were (a) primary caregiver aged 18+ and without cognitive impairment, (b) providing ≥14 care hours per week to a relative with mild-to-moderate Alzheimer's disease, and (c) scoring ≥3 on the Hamilton Depression Rating Scale. Exclusion criterion was care-recipient having parkinsonism or other forms of dementia. Interventions: The benefit-finding intervention was evaluated against two treatment-as-usuals, namely, simplified psychoeducation (lectures only) and standard psychoeducation. Each intervention lasted eight weeks, with a 2-hour session per week. Randomization into these conditions was based on center/clinic membership. Measurements: Primary outcome was depressive symptom. Secondary outcomes were Zarit Burden Interview, role overload, and psychological well-being. Self-efficacy beliefs and positive gains were treated as mediators. Measures were collected at baseline and posttreatment. Results: Regression analyses showed BF treatment effects on all outcomes when compared with SIM-PE, and effects on depressive symptoms and Zarit burden when compared with STD-PE. Effect sizes were medium-to-large for depressive symptoms (d=-0.77– -0.96), and medium for the secondary outcomes (d=|0.42–0.65|). Furthermore, using the bootstrapping method, we found significant mediating effects by self-efficacy in controlling upsetting thoughts and positive gains, with the former being the primary mediator. Conclusions: Finding positive gains reduces depressive symptoms and burden and promotes psychological well-being primarily through enhancing self-efficacy in controlling upsetting thoughts

Education and awareness of modern health care amongst aboriginal people: the case of the Jakuns of Peninsular Malaysia

Previous studies have indicated that the resettlement of the Orang Asli communities into areas nearer to towns was with the intention of improving the health conditions of the aboriginals. Subsequent researches have since focused on the relation between mainstream orthodox medical approaches and traditional healing practices in search of improved approaches to advance further the health cause of the aboriginal communities. However, none of these works have addressed the central question of how the Orang Asli have been adapting themselves to the mainstream healthcare system while still holding strong beliefs in their traditional medicine. To close the gap this study examined the readiness and intentions of the Orang Asli in adapting to modern health care approach amidst old traditional health beliefs and healings practices. A qualitative study based on in-depth interviews and field observations was carried out at a Jakun village of Kampung Kedaik, Rompin, Pahang involving 12 male and 13 female informants between 18 – 70 years old. Results of the study showed that as the Orang Asli people received proper education they appeared to think about health differently. Most of the informants preferred modern over traditional medicine predominantly because of their deteriorating faith in, and relative inaccessibility to traditional medicine. The findings implied that in this modern day most of the indigenous communities were open to social change which in this context included modern health care so as to improve their health conditions

Robust transmission and reconstruction of fragile optical states

We propose a scheme by which signals carried by a coherent optical source close to the quantum noise limit can be amplified, making them more robust against losses, and then reconstructed at a remote site. The amplitude signal-to-noise ratio, the absolute amplitude noise level, and optical coherence are preserved. The scheme utilizes electro-optic feedforward and laser injection locking. We investigate the performance of the scheme as a quantum nondemolition device. [S1050-2947(97)02411-6]

Aetiology of allergic rhinitis in Hong Kong

ABSTRACTIn a 1993 survey, allergic rhinitis was identified as the most common allergic disease in Hong Kong, affecting 29.1% of schoolchildren. Recently (1995), the International Study of Asthma and Allergies in Childhood (ISAAC) also reported 44.5% current rhinitis among Hong Kong teenagers. Our objective was to study the aetiology of allergic rhinitis in Hong Kong using serological tests of allergen sensitization. In 57 allergic rhinitis patients and in the same number of age- and sex-matched controls the following were measured: serum total IgE, mixed aeroallergen IgE (Phadiatop™) and specific IgE versus house dust mite (HDM), cockroach, cat and dog dander, mould mixture (Penicillium, Cladosporium, Aspergillus and Alternaria species) and four local pollens (Bermuda grass, Timothy, ragweed and mugwort). Compared with controls, allergic rhinitis patients (26 males, 31 females; mean (± SD) age 25 ±11 years) had a significantly elevated serum total IgE concentration (mean ± SEM: 496 ± 88 vs 179 ± 38 kU/L) and an increased proportion of positive Phadiatop (95 vs 33%) and specific IgE tests versus HDM (90 vs 44%) and cockroach (42 vs 9%; Mann-Whitney U-test and χ2 tests all P < 0.005). There was no significant difference in sensitization to other allergens tested. House dust mite and cockroach are ubiquitous in Hong Kong with a warm, humid climate and crowded living conditions. Their identification as aetiological agents of allergic rhinitis should help in the development of environmental strategies for reducing the inhalant allergen load to prevent and control this prevalent and costly health problem in our community

Genotype Distribution and Sequence Variation of Hepatitis E Virus, Hong Kong

Most acute cases of infection with hepatitis E virus (HEV) in Hong Kong were autochthonous, sporadic, and occurred in older adults. All except 1 isolate belonged to genotype 4; most were phylogenetically related to swine isolates. The epidemiology is similar to that in industrialized countries, where zoonosis is the major source of HEV infection in humans

Characterization of the QUartz Photon Intensifying Detector (QUPID) for Noble Liquid Detectors

Dark Matter and Double Beta Decay experiments require extremely low radioactivity within the detector materials. For this purpose, the University of California, Los Angeles and Hamamatsu Photonics have developed the QUartz Photon Intensifying Detector (QUPID), an ultra-low background photodetector based on the Hybrid Avalanche Photo Diode (HAPD) and entirely made of ultraclean synthetic fused silica. In this work we present the basic concept of the QUPID and the testing measurements on QUPIDs from the first production line. Screening of radioactivity at the Gator facility in the Laboratori Nazionali del Gran Sasso has shown that the QUPIDs safely fulfill the low radioactive contamination requirements for the next generation zero background experiments set by Monte Carlo simulations. The quantum efficiency of the QUPID at room temperature is > 30% at the xenon scintillation wavelength. At low temperatures, the QUPID shows a leakage current less than 1 nA and a global gain of 10^5. In these conditions, the photocathode and the anode show > 95% linearity up to 1 uA for the cathode and 3 mA for the anode. The photocathode and collection efficiency are uniform to 80% over the entire surface. In parallel with single photon counting capabilities, the QUPIDs have a good timing response: 1.8 +/- 0.1 ns rise time, 2.5 +/- 0.2 ns fall time, 4.20 +/- 0.05 ns pulse width, and 160 +/- 30 ps transit time spread. The QUPIDs have also been tested in a liquid xenon environment, and scintillation light from 57Co and 210Po radioactive sources were observed.Comment: 15 pages, 22 figure