Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold

We study the imaginary part of the effective $ac$ conductivity as well as its distribution probability for vanishing losses in 2D composites. This investigation showed that the effective medium theory provides only informations about the average conductivity, while its fluctuations which correspond to the field energy in this limit are neglected by this theory.Comment: 6 pages, 2 figures, submitted to Phys.Rev.

Localization and Absorption of Light in 2D Composite Metal-Dielectric Films at the Percolation Threshold

We study in this paper the localization of light and the dielectric properties of thin metal-dielectric composites at the percolation threshold and around a resonant frequency where the conductivities of the two components are of the same order. In particular, the effect of the loss in metallic components are examined. To this end, such systems are modelized as random $L-C$ networks, and the local field distribution as well as the effective conductivity are determined by using two different methods for comparison: an exact resolution of Kirchoff equations, and a real space renormalization group method. The latter method is found to give the general behavior of the effective conductivity but fails to determine the local field distribution. It is also found that the localization still persists for vanishing losses. This result seems to be in agreement with the anomalous absorption observed experimentally for such systems.Comment: 14 page latex, 3 ps figures. submitte

The Influence of Gravity on Fluid-Structure Impact

Fluid-structure interaction is a well-known and complicated problem. Its formulation requires simpli�cations in modelling, and usually the presence of gravity is one aspect which is neglected, especially in violent impact. In this thesis we account for the in uence of gravity on two physically di�erent but mathematically similar two-dimensional ows. First (in Chapters 2{4), sloshing impact of a standing wave on the lid of a rigid tank, and second (in Chapter 5), impact of a rigid blunt body entering water which is initially at rest. Chapter 1 presents the motivation, literature, aim and structure of the thesis. In Chapter 2, gravity is neglected and model equations are solved analytically, in particular the linearised hydrodynamic problem with and without the lid using the Wagner approximation, time and coordinate stretching, and displacement potential. Chapter 3, introduces gravity into the formulation and the model is solved semi-analytically to determine its in uence on the width of the wetted region and on the pressure distribution on the lid during impact. We numerically �nd the e�ect of gravity on the moving contact points, hydrodynamic pressure, and surface elevation in Chapter 4. Chapter 5 studies the in uence of gravity on the impact of a blunt body entering vertically with a constant speed into an initially at water. All problems are formulated and solved within the Wagner model. In both problems we found visible e�ects of gravity on the positions of moving contact points after the early stage of impact. Gravity shortens the size of the wetted region. Consequently, the velocities of the contact points are decreased by gravity. The effect of gravity on the surface elevation is shown for both problems. Negative hydrodynamic pressures and forces are found during the ii sloshing impact stage when gravity is neglected. Numerically, it was found that gravity decreases the hydrodynamic pressure on the lid of the tank. Similarly the hydrodynamic pressure is found to be decreased by gravity in the water-entry problem. Also in the waterentry problem it is shown that gravity increases both the thickness and the mass ux into the spray jets. Also the total energy (potential and kinetic) of the system, and t

Relative Hypocalcaemia and Muscle Cramps in Patients Receiving Imatinib for Gastrointestinal Stromal Tumour

Purpose. Imatinib treatment causes muscle cramps in up to 40% of patients, but their pathogenesis is unknown. We present a case series illustrating an association between imatinib, relative hypocalcaemia, and the development of cramps. Patients. The index patient developed muscle spasms and cramps after receiving imatinib for gastrointestinal stromal tumour (GIST) for 5 months. The adjusted serum calcium had dropped to the lower limit of normal. The low serum calcium and muscle cramps improved on stopping imatinib and recurred on rechallenge. We reviewed the medical records of 16 further patients. Results. Two patients reported muscle cramps (12%). There was a rapid and sustained reduction in adjusted serum calcium in the first 6 months from 2.45 ± 0.11 mmol/L (mean ± SD) to 2.30 ± 0.08 mmol/L (p = 0.025). Conclusion. Imatinib treatment of GIST is associated with reduction in serum calcium which may explain the development of neuromuscular symptoms. In patients receiving imatinib, serum electrolytes should be monitored and muscle cramps treated by correction of serum calcium, or an empirical trial of quinine sulphate

Monte Carlo simulation of the transmission of measles: Beyond the mass action principle

We present a Monte Carlo simulation of the transmission of measles within a population sample during its growing and equilibrium states by introducing two different vaccination schedules of one and two doses. We study the effects of the contact rate per unit time $\xi$ as well as the initial conditions on the persistence of the disease. We found a weak effect of the initial conditions while the disease persists when $\xi$ lies in the range 1/L-10/L ($L$ being the latent period). Further comparison with existing data, prediction of future epidemics and other estimations of the vaccination efficiency are provided. Finally, we compare our approach to the models using the mass action principle in the first and another epidemic region and found the incidence independent of the number of susceptibles after the epidemic peak while it strongly fluctuates in its growing region. This method can be easily applied to other human, animals and vegetable diseases and includes more complicated parameters.Comment: 15 pages, 4 figures, 1 table, Submitted to Phys.Rev.

Markers of bone turnover for the management of patients with bone metastases from prostate cancer

Although increased bone formation is a prominent feature of patients with osteosclerotic metastases from prostate cancer, there is also some evidence for increased bone resorption. The aim of this study was to compare the clinical utility of new bone resorption markers to that of bone formation in patients with bone metastases from prostate cancer before and after bisphosphonate treatment. Thirty-nine patients with prostate cancer and bone metastasis, nine patients with prostate cancer without bone metastases, nine patients with benign prostatic hyperplasia and 355 healthy age-matched men were included. Urinary non-isomerized (α CTX) and β isomerized (β CTX) type I collagen C-telopeptides (CTX) and a new assay for serum CTX were used to assess bone resorption. Bone formation was determined by serum osteocalcin, serum total (T-ALP) and bone (BAP) alkaline phosphatase and serum type I collagen C-terminal propeptide (PICP). Fourteen patients with bone metastases were also evaluated 15 days after a single injection of the bisphosphonate pamidronate (120 mg). Levels of all bone formation and bone resorption markers were significantly (P< 0.006–0.0001) higher in patients with prostate cancer and bone metastasis than in patients with benign prostatic hyperplasia, patients with prostate cancer without bone metastases and healthy controls. In patients with bone metastases the median was increased by 67% for serum osteocalcin, 128% for T-ALP, 138% for BAP, 79% for PICP, 220% for urinary α CTX, 149% for urinary β CTX and 214% for serum CTX. After bisphosphonate treatment all three resorption markers significantly decreased by an average of 65% (P = 0.001), 71% (P = 0.0010) and 61% (P = 0.0015) for urinary α CTX, urinary β CTX and serum CTX, respectively, whereas no significant change was observed for any bone formation markers. Patients with prostate cancer and bone metastases exhibit a marked increase in bone resorption, which decreases within a few days of treatment with pamidronate. These findings suggest that these new resorption markers may be useful for the management of these patients. © 2000 Cancer Research Campaig