Self-irradiation enhanced tritium solubility in hydrogenated amorphous and crystalline silicon

Experimental results on tritium effusion, along with the tritium depth profiles, from hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) tritiated in tritium (T2) gas at various temperatures and pressures are presented. The results indicate that tritium incorporation is a function of the material microstructure of the as-grown films, rather than the tritium exposure condition. The highest tritium concentration obtained is for a-Si:H deposited at a substrate temperature of 200°C. The tritium content is about 20 at. % on average with a penetration depth of about 50 nm. In contrast, tritium occluded in the c-Si is about 4 at. % with penetration depth of about 10 nm. The tritium concentration observed in a-Si:H and c-Si is much higher than the reported results for the post-hydrogenation process. β irradiation appears to catalyze the tritiation process and enhance tritium dissolution in the silicon matrix. The combination of tritium decay and β-induced ionizations results in formation of reactive species of tritium (tritium atoms, radicals, and ions) that readily adsorb on silicon. The electron bombardment of the silicon surface and subsurface renders it chemically active thereby promoting surface adsorption and subsurface diffusion of tritium, thus leading to tritium occlusion in the silicon matrix. Gaussian deconvolution of tritium effusion spectra yields two peaks for a-Si:H films tritiated at high temperature (250°C), one low temperature (LT) peak which is attributed to tritiated clusters and higher order tritides, and another high temperature peak which is attributed to monotritides. Activation energy of 2.6-4.0 eV for the LT peak was found. © 2011 American Institute of Physics

Application of a valveless impedance pump in a liquid cooling system

2012-2013 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A practical and open source implementation of IEC 61850-7-2 for IED monitoring applications

A new open source mapping of IEC 61850-7-2 to web services has been defined and implemented. This work is useful for rapidly implementing user interfaces—particularly web-based interfaces—for monitoring and controlling Intelligent Electronic Devices (IEDs) from multiple vendors. The web service mapping has been implemented using the Hypertext Transfer Protocol (HTTP), with a message format in JavaScript Object Notation (JSON). This approach requires a simple and ubiquitous software stack for its implementation, which is a significant advantage over existing client-server communications mappings. The use of an open source paradigm allows for the rapid iteration and refinement of the design, implementation, and testing of the internal details of the proposed protocol stack, in a collaborative manner. These developments are of immediate interest to users of IEC 61850 and are particularly relevant to the IEC 61850 standardization process

An exploration of patient-reported symptoms in systemic lupus erythematosus and the relationship to health-related quality of life

Objective: The aim of this study was to explore the most distressing symptoms of systemic lupus erythematosus (SLE) and determine how these relate to health-related quality of life (HRQoL), anxiety/depression, patient demographics and disease characteristics (duration, activity, organ damage). Methods: In a cross-sectional study, patients with SLE (n=324, age 18-84 years) gave written responses regarding which SLE-related symptoms they experienced as most difficult. Their responses were categorized. Within each category, patients reporting a specific symptom were compared with non-reporters and analyzed for patient demographics, disease duration, results from the questionnaires: Medical Outcomes Study Short-Form 36, Hospital Anxiety and Depression Scale, Systemic Lupus Activity Measure, SLE disease activity index and the Systemic Lupus International Collaboration Clinics/American College of Rheumatology damage index. Results: 23 symptom categories were identified. Fatigue (51%), Pain (50%) and Musculoskeletal distress (46%) were most frequently reported. Compared with non-reporters, only patients reporting Fatigue showed statistically significant impact on both mental and physical components of HRQoL.. Patients with no present symptoms (10%) had higher HRQoL (p<0.001) and lower levels of depression (p<0.001), anxiety (p<0.01) and disease activity (SLAM) (p<0.001). Conclusion: Fatigue, pain or musculoskeletal distress dominated the reported symptoms in approximately half of the patients. Only patients reporting Fatigue scored lower on both mental and physical aspects of HRQoL. Our results emphasize the need for further support and interventions to ease the symptom load and improve HRQoL in patients with SLE. Our findings further indicate that this need is particularly urgent for patients with symptoms of pain or fatigue

Physicists attempt to scale the ivory towers of finance

Physicists have recently begun doing research in finance, and even though this movement is less than five years old, interesting and useful contributions have already emerged. This article reviews these developments in four areas, including empirical statistical properties of prices, random-process models for price dynamics, agent-based modeling, and practical applications.Comment: 13 pages, 5 figure

A Computational and Experimental Study of the Regulatory Mechanisms of the Complement System

The complement system is key to innate immunity and its activation is necessary for the clearance of bacteria and apoptotic cells. However, insufficient or excessive complement activation will lead to immune-related diseases. It is so far unknown how the complement activity is up- or down- regulated and what the associated pathophysiological mechanisms are. To quantitatively understand the modulatory mechanisms of the complement system, we built a computational model involving the enhancement and suppression mechanisms that regulate complement activity. Our model consists of a large system of Ordinary Differential Equations (ODEs) accompanied by a dynamic Bayesian network as a probabilistic approximation of the ODE dynamics. Applying Bayesian inference techniques, this approximation was used to perform parameter estimation and sensitivity analysis. Our combined computational and experimental study showed that the antimicrobial response is sensitive to changes in pH and calcium levels, which determines the strength of the crosstalk between CRP and L-ficolin. Our study also revealed differential regulatory effects of C4BP. While C4BP delays but does not decrease the classical complement activation, it attenuates but does not significantly delay the lectin pathway activation. We also found that the major inhibitory role of C4BP is to facilitate the decay of C3 convertase. In summary, the present work elucidates the regulatory mechanisms of the complement system and demonstrates how the bio-pathway machinery maintains the balance between activation and inhibition. The insights we have gained could contribute to the development of therapies targeting the complement system.Singapore. Ministry of Education (Grant T208B3109)Singapore. Agency for Science, Technology and Research (BMRC 08/1/21/19/574)Singapore-MIT Alliance (Computational and Systems Biology Flagship Project)Swedish Research Counci

Sentinel surveillance for human enterovirus 71 in Sarawak, Malaysia: lessons from the first 7 years

BACKGROUND: A major outbreak of human enterovirus 71-associated hand, foot and mouth disease in Sarawak in 1997 marked the beginning of a series of outbreaks in the Asia Pacific region. Some of these outbreaks had unusually high numbers of fatalities and this generated much fear and anxiety in the region. METHODS: We established a sentinel surveillance programme for hand, foot and mouth disease in Sarawak, Malaysia, in March 1998, and the observations of the first 7 years are described here. Virus isolation, serotyping and genotyping were performed on throat, rectal, vesicle and other swabs. RESULTS: During this period Sarawak had two outbreaks of human enterovirus 71, in 2000 and 2003. The predominant strains circulating in the outbreaks of 1997, 2000 and 2003 were all from genogroup B, but the strains isolated during each outbreak were genetically distinct from each other. Human enterovirus 71 outbreaks occurred in a cyclical pattern every three years and Coxsackievirus A16 co-circulated with human enterovirus 71. Although vesicles were most likely to yield an isolate, this sample was not generally available from most cases and obtaining throat swabs was thus found to be the most efficient way to obtain virological information. CONCLUSION: Knowledge of the epidemiology of human enterovirus 71 transmission will allow public health personnel to predict when outbreaks might occur and to plan interventions in an effective manner in order to reduce the burden of disease

The socioeconomic burden of SLE.

Systemic lupus erythematosus (SLE) is a chronic, relapsing-remitting, multisystemic autoimmune inflammatory disorder that predominantly affects women of childbearing age. Much has been written about the clinical course and long-term damage associated with SLE, as well as the reduced life expectancy of patients with this condition. In addition, studies have emphasized the socioeconomic and psychosocial impact of SLE, although the monetary cost of caring for patients with the disorder has only been evaluated in a modest number of studies and a restricted number of countries. SLE has a negative impact on quality of life and is associated with high health-care costs and significant productivity loss. Factors associated with increased cost of SLE include long disease duration, high disease activity and damage, poor physical and mental health, and high education and employment levels. Similarly, high disease activity and damage, poor physical health, certain disease manifestations, as well as poor family and social support are associated with poor health-related quality of life outcomes. SLE incurs a great burden on both the patient and society. Long-term prospective studies should be encouraged to monitor the costs and psychosocial impact of this condition, and to better understand the factors that are associated with poor outcomes.postprin

Validation of two generic patient-reported outcome measures in patients with type 2 diabetes

<p>Abstract</p> <p>Background</p> <p>Prior to using a generic patient-reported outcome measure (PRO), the measure should be validated within the target population. The purpose of the current study was to validate two generic measures in patients with type 2 diabetes.</p> <p>Methods</p> <p>Patients with type 2 diabetes in Scotland and England completed two generic measures: EQ-5D and Psychological General Well-Being Index (PGWB). Two diabetes-specific measures were administered: ADS and DSC-R. Analyses assessed reliability and validity.</p> <p>Results</p> <p>There were 130 participants (53 Scotland; 77 England; 64% male; mean age = 55.7 years). Responses on the EQ-5D and PGWB reflected moderate impairment consistent with previous diabetes samples: mean EQ-5D Index score, 0.75; EQ-5D VAS, 68.8; PGWB global score, 67.9. All scales of the PGWB demonstrated good internal consistency reliability (Cronbach's alpha = 0.77 to 0.97). The EQ-5D and PGWB demonstrated convergent validity through significant correlations with the ADS (r = 0.48 to 0.61), DSC-R scales (r = 0.33 to 0.81 except ophthalmology subscale), and Body Mass Index (r = 0.15 to 0.38). The EQ-5D and PGWB discriminated between groups of patients known to differ in diabetes-related characteristics (e.g., history of hypoglycemia).</p> <p>Conclusion</p> <p>Results support the use of the EQ-5D and PGWB among patients with type 2 diabetes, possibly in combination with condition-specific measures.</p