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We report on this work a model to accurately predict the electrical behavior of double-heterostructure GaN/SiC blue light-emitting diodes up to microwave frequencies. A procedure to extract the series resistance (Rs) from the reflection coefficient is suggested. This procedure offers the advantage of using measurements without any bias current and therefore the obtained values of Rs are influenced neither by the device heating nor by inaccuracies in the calculation of the ideality factor. The junction capacitance and conductance measured in the range 1 kHz–10 MHz shows two different relaxation mechanisms, and the total capacitance can be fitted very accurately to a double Lorentzian function. Blue light-emitting diodes and lasers based on gallium nitride (GaN) semiconductor compounds represent one of the most important breakthroughs in electronics and optoelectronics of recent years. The combination of silicon carbide (SiC) and GaN has recently enabled low-cost blue-emitting diodes to be introduced in industry. [ABSTRACT FROM AUTHOR]

The aim of this study is to calculate the membrane elastic energy for the different shapes observed in the discocyte-stomatocyte sequence. This analysis can provide a better quantitative understanding of the hypothesis put forward over the last decades to explain how red blood cells produce and maintain their typical shape. For this purpose, we use geometrical models based on parametric equations. The energy model considered for the elastic properties of RBC membrane includes the local and nonlocal resistance effects of the bilayer to bending. In particular, the results confirm the discocyte as the lowest energy value configuration among the sets of different red blood cell deformations considered in the sequence., (© 2013.)

We present simple parametric equations in terms of Jacobi elliptic functions that provide a realistic model of abnormal variations in size which maintain the biconcave shape of a normal erythrocyte (anisocytosis) and abnormal variations in shape which maintain the original volume of the erythrocyte (poikilocytosis), as well as continuous deformations from the normal to the altered shapes. We illustrate our results with parameterizations of microcytes, macrocytes, and stomatocytes, and we apply these parameterizations to the numerical calculation of the induced transmembrane voltage in microcytes, macrocytes, and stomatocytes exposed to an external electromagnetic field of 1800 MHz.

In this article, the transmembrane voltage induced on erythrocyte, codocyte, ovalocyte and spherocyte cell models exposed to a linearly polarised electromagnetic plane wave of frequency 1800 MHz is calculated. For this purpose, a finite element (FE) numerical technique with adaptive meshing is used. The results show that the value of the induced voltage on the original erythrocyte shape is higher than the one observed on the rest of the altered cell geometries studied. The erythrocyte shape and the membrane electric permittivity are shown to play a fundamental role on the values of the induced transmembrane voltage.

This paper studies the internal electric field distribution in human erythrocytes exposed to MW radiation. For this purpose, an erythrocyte cell model is exposed to linearly polarized electromagnetic (EM) plane waves of frequency 900 MHz and the electric field within the cell is calculated by using a finite element (FE) technique with adaptive meshing. The results obtained show the dependence of the induced electric field distribution on the main modelling parameters, i.e., the electrical properties (permittivity and conductivity) of the membrane and cytoplasm and the orientation of the cell with respect to the applied field. It is found that for certain orientations, the field amplification within the membrane of the erythrocyte shape cell can be higher than the one observed in an equivalent simple spheroidal geometry cell, commonly used in bioelectromagnetism. The present work shows that a better insight of the interaction of electromagnetic fields with basic biological structures is obtained when the most possible realistic cell shape is used.

This paper shows the importance of using realistic cell shapes with the proper geometry and orientation to study the mechanisms of direct cellular effects from radiofrequency (RF) exposure. For this purpose, the electric field distribution within erythrocyte, rod and ellipsoidal cell models is calculated by using a finite element technique with adaptive meshing. The three cell models are exposed to linearly polarized electromagnetic plane waves of frequencies 900 and 2450 MHz. The results show that the amplification of the electric field within the membrane of the erythrocyte shape cell is more significant than that observed in other cell geometries. The results obtained show the dependence of the induced electric field distribution on frequency, electrical properties of membrane and cytoplasm and the orientation of the cell with respect to the applied field. The analysis of the transition of an erythrocyte shape to an ellipsoidal one shows that a uniformly shelled ellipsoid model is a rough approximation if a precise simulation of bioeffects in cells is desired.

Objectives: To determine the efficacy of a three-fold reduced dose (RD, 27 mg) of intravesical bacille Calmette-Guérin (BCG) against the standard dose (81 mg) in patients with superficial bladder cancer, assessing recurrence, progression and differences in toxicity., Patients and Methods: Five hundred patients with superficial bladder cancer (Ta, T1, Tis) were enrolled and randomly assigned to be treated after transurethral resection of all visible lesions with intravesical BCG Connaught strain (weekly x six and thereafter fortnightly x six) either with the standard or RD instillation., Results: All but one of the 500 patients were evaluable for efficacy and toxicity (252 in the standard arm and 247 in the RD arm). The median follow-up was 69 months (maximum 104); 71 (28%) patients in the standard arm and 76 (31%) in the RD arm developed recurrences; the median time to recurrence has not yet been attained, but at 5 years the mean (sd) percentage of recurrence-free patients was 70.5 (3.12) and 70.4 (3.1) for the standard and RD arms, respectively. In patients presenting with multifocal tumours, the standard dose was more effective against recurrences than the RD (P=0.0151). In those with G3 and high-risk tumours overall, the superiority of the standard dose was marginal (P=0.060 and P=0.082). Twenty-nine (11.5%) tumours in the standard arm and 33 (13.3%) in the RD arm progressed to invasive disease; the median time to progression has not yet been attained, but the percentage of progression-free patients at 5 years was 88.8 (2.23) and 86.9 (2.31) for the standard and RD arms, respectively. The standard dose was more effective than the RD against progression only in patients with multifocal disease (P=0.048). Twelve (4.8%) cystectomies were performed in the standard and 15 (6.1%) in the RD arm. Currently, 106 (21.2%) patients have died, but only 38 (7.6%) from bladder cancer, i.e. 20 (7.9%) in the standard and 18 (7.5%) in RD arm. Overall the disease-specific death rate was lower for those patients who completed the scheduled treatment. The cause-specific survival at 5 years did not differ between the arms (P=0.76) but there was a trend toward better cause-specific survival for patients with multifocal tumours in the standard arm. Toxicity differed between the arms, significantly more patients having no toxicity in the RD arm, and fewer having delayed instillations or withdrawing. However, severe systemic toxicity occurred even in patients treated with the RD, in a similar proportion to those receiving the standard dose., Conclusion: Overall, the RD gave similar results for recurrence and progression but with significantly less toxicity. However, patients with multifocal tumours fared better with the standard dose and there was a trend towards better recurrence rates in patients with high-risk tumours. We recommend continuing to use the standard dose for high-risk tumours, while we consider the reduced dose safe and effective for intermediate-risk lesions and for maintenance schedules.

We present a review of the treatments of the urinary calculations carried out in the Lithotrity Unit in its first five years of working with the Dornier lithotriptor MFL-5000. We describe the location and size of the calculations, distribution by age and sex of the patients, energy applied and time employed, and we compare our retreatment index and the number of sessions per calculation with those published by other authors.

We present a case of hypercalcemia associated with a renal pelvis squamous neoplasm. Severe hyperleukocytosis was also present, resembling a leukaemoid reaction. After failure of standard therapy, we performed a trial of low dose epirubicin in this patient, obtaining a short-term clinical remission. Although a palliative non-toxic effect seems to be achievable with this approach, further studies are needed to ascertain the role of chemotherapy in the long-term control of this condition.

Sclerosant therapy for different pathological conditions (testicular hydrocele, pneumothorax) is a little known and scantily used procedure in the clinical setting. We have developed a surgical procedure in the dog that permits reproducing adult hydrocele. This experimental model is useful for morphometric assessment of the sclerosant effects of the commonly used agents (magnesium silicate hydrate, carbolic acid, ethanolamine oleate, hydroxytetracycline chlorhydrate and quinacrine chlorhydrate). Our results show that the degree of sclerosis achieved with quinacrine and hydrotetracycline is significantly superior to that obtained with other agents.

We present a case of a double left ureter, one of which branched with one blind branch, which has not been described in the literature.

A case is presented of spontaneous rupture in a pathological bladder. The authors point out the importance of retrograde cystographies to reveal intraperitoneal ruptures in te bladder and to check for the existence of associated lesions. A review is made of the etiology, clinical picture and treatment of spontaneous, intraperitoneal rupture of the bladder.