Dynamical behaviour of intrinsic Josephson junctions

Intrinsic Josephson Junctions (IJJs) are the subject of much of research due to their potential applications as high frequency oscillators and detectors in the THz range. A number of previous studies use a single junction model to explain their observations, as no fully agreed model for coupled IJJs exists. The influence of one or more IJJs in the voltage state on other junctions in the IJJ array is not yet fully understood. I have studied the dynamical behaviour of Tl_2Ba_2CaCu_2O_8 thin film IJJ arrays, focussing on how one junction in the voltage state influences the other junctions. This I have done by measuring (a) the switching current distributions, and (b) the influence of r.f. irradiation on the DC current-voltage characteristics. I have compared the switching current distributions when switching from the supercurrent branch with those when switching from the first quasiparticle branch. The supercurrent branch was found to be overdamped at the escape frequency whereas the first quasiparticle branch is underdamped, resulting in a larger switching current for the former than the latter. RF irradiation suppresses the mean switching current on the supercurrent branch accompanied by the appearance of a low-voltage flux flow branch. There is however no effect on the switching current of the quasiparticle branches. I explain these results in terms of the dissipative environment in which the junctions are embedded, and, furthermore, that switching of a single IJJ into the voltage state significantly changes the dissipation. IJJs were sub sequently isolated from their environment by FIB-deposited tungsten resistors of resistance between 100 and 500 Ω. The complete resistor-junction-resistor (RJR) structure is multibranched and shows a change in the DC current-voltage characteristics below and above the T^c of the tungsten. However, the presence of high resistance in the RJR structure at 4.2 K needs further investigation

Effects of Trade Openness on Economic Growth: The Case of African Countries

The relationship between trade and productivity has not been established theoretically. Some researchers have indeed found some, if not complete, support for the view that increasing openness has a positive impact on productivity. This study used a Cobb-Douglas production function as in Miller and Upadhyay (2000) to estimate the impact of FDI, exchange rate, capital-labor ratio and trade openness on GDP for 38 African countries from 1980 to 2008. Data were transformed to natural logs and estimated using alternative panel models; which included one- or-two-way fixed or random effects models. The results found trade openness having a positive relationship with GDP; which is comparable to findings of Ahmed et al.; (2008).Trade Openness, Productivity, Africa, Cobb Douglas Production Function., International Development, International Relations/Trade, Productivity Analysis,

Qualitative Assessment Of Bottled Water In The Middle East

Many brands of bottled water are being produced in the Middle East including the Gulf Cooperation Council (GCC) countries. Over fourteen brands of bottled water could be found in the market of Doha. Use of bottled water has kept on increasing in this region. Reasons for the increase in use of bottled water for drinking have been discussed. The raw water source for the bottled water is groundwater. Most of the manufacturers of the bottled water claim bottled water as "Natural Mineral Water" which is contrary to the definition suggested by the International Bottled Water Association of Washington D.C. In fact there is no such thing as "mineral water" and the term is a misnomer. Samples of various brands of bottled water available in Doha and municipal water were collected during 1993 and 1994 for physical, chemical, and bacteriological analysis. All the samples were found potable and safe for drinking and conform to various drinking water standards. The physical and chemical composition of bottled water varies with time but the concentration of constituents printed on the labels of bottles is always the same. It may be preferable to print the range of concentration on the labels rather than a single value. Moreover the analysis should be monitored and certified by a competent authority, and should be displayed on the label

Study protocol: Delayed intervention randomised controlled trial within the Medical Research Council (MRC) Framework to assess the effectiveness of a new palliative care service

Background: Palliative care has been proposed to help meet the needs of patients who suffer progressive non-cancer conditions but there have been few evaluations of service development initiatives. We report here a novel protocol for the evaluation of a new palliative care service in this context. Methods/Design: Using the MRC Framework for the Evaluation of Complex Interventions we modelled a new palliative care and neurology service for patients severely affected by Multiple Sclerosis (MS). We conducted qualitative interviews with patients, families and staff, plus a literature review to model and pilot the service. Then we designed a delayed intervention randomised controlled trial to test its effectiveness as part of phase II of the MRC framework. Inclusion criteria for the trial were patients identified by referring clinicians as having unresolved symptoms or psychological concerns. Referrers were advised to use a score of greater than 8 on the Expanded Disability Scale was a benchmark. Consenting patients newly referred to the new service were randomised to either receive the palliative care service immediately (fast-track) or after a 12-week wait (standard best practice). Face to face interviews were conducted at baseline (before intervention), and at 4–6, 10–12 (before intervention for the standard-practice group), 16– 18 and 22–24 weeks with patients and their carers using standard questionnaires to assess symptoms, palliative care outcomes, function, service use and open comments. Ethics committee approval was granted separately for the qualitative phase and then for the trial. Discussion: We publish the protocol trial here, to allow methods to be reviewed in advance of publication of the results. The MRC Framework for the Evaluation of Complex Interventions was helpful in both the design of the service, methods for evaluation in convincing staff and the ethics committee to accept the trial. The research will provide valuable information on the effects of palliative care among non-cancer patients and a method to evaluate palliative care in this context

Risk Factors of Diarrhoea in Malnourished Children Under Age of 5 Years

Background: Acute infectious enteritis remains one of the commonest causes of death among infants and children in developing countries. Acute enteritis is defined as a loss of stool consistency with pasty or liquid stools, and/or an increase in stool frequency to more than three stools in 24 hours with or without fever or vomiting. Human survival depends on the secretion and reabsorption of fluid and electrolytes in the intestinal tract. The objective of the study is to evaluate the risk factors of diarrhoea in children under age of 5 years. Methodology: It was an observational study. Study was completed in about six months. Non-probability purposive sampling technique was used. In this study, 270 samples were taken from Diarrheal ward of The Children Hospital Lahore, Pakistan. Results: In this study, out of 270 patients, 58.52% were males and 41.48% were females. 90.37% patients were vaccinated. 54.81% had weaning history. 91.85% patients had feeding history. 29.26% had blood in stool. 96.67% patients were dehydrated. 95.56% patients had loose watery diarrhoea. 62.96% patients used boiled water. 58.52% patients consumed less than half litre of water, 30.00% patients consumed 1 litre of water and 11.48% patients consumed > 1 litre of water. 49.18% patients had proper hygiene. 38.15% mothers of patients were well educated. 40.37% patients had model household condition. 57.41% patients lived in rural area and 42.59% patients lived in urban area. Conclusion: The variation in the level of diarrheal morbidity was well explained by maternal education, income, personal hygiene, refuse disposal system and the effect of health extension programme

Wiener Reconstruction of Large-Scale Structure from Peculiar Velocities

We present an alternative, Bayesian method for large-scale reconstruction from observed peculiar velocity data. The method stresses a rigorous treatment of the random errors and it allows extrapolation into poorly sampled regions in real space or in k-space. A likelihood analysis is used to determine the fluctuation power spectrum, followed by a Wiener Filter (WF) analysis to obtain the minimum-variance mean fields of velocity and mass density. Constrained Realizations (CR) are then used to sample the statistical scatter about the WF mean field. The WF/CR method is applied as a demonstration to the Mark III data with 1200 km/s, 900 km/s, and 500 km/s resolutions. The main reconstructed structures are consistent with those extracted by the POTENT method. A comparison with the structures in the distribution of IRAS 1.2Jy galaxies yields a general agreement. The reconstructed velocity field is decomposed into its divergent and tidal components relative to a cube of +/-8000 km/s centered on the Local Group. The divergent component is very similar to the velocity field predicted from the distribution of IRAS galaxies. The tidal component is dominated by a bulk flow of 194 +/- 32 km/s towards the general direction of the Shapley concentration, and it also indicates a significant quadrupole.Comment: 28 pages and 8 GIF figures, Latex (aasms4.sty), submitted to ApJ. Postscript version of the figures can be obtained by anonymous ftp from: ftp://alf.huji.ac.il/pub/saleem