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The programming method used to adapt an existing time-domain electrical circuit simulator to the parallel computation is presented. The originality of the simulator results in the semiconductor device numerical physical modeling. Thus, the organization of the existing software, initially developed to be run on a monoprocessor sequential Unix workstation, is firstly detailed. Accounting for specifications at once regarding the effort necessary to modify the software, the wished simulator application field and the constraints resulting from the available computer, two levels of parallelization have been pointed out and implemented by means of the message passing interface parallel programming tool. As an illustration, some results concerning the simulation of a microwave monolithic integrated circuit (MMIC), especially a 2–40 GHz HEMT transistor cascode stage distributed amplifier, are presented. Circuits of increasing complexity have been considered. The evaluation of the sequential/parallel computation ratio demonstrates that significant gains can be expected from the parallel computation opening the way to analysis of the operation of MMICs of mean complexity by means of a numerical physical approach. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background and Objectives: Block of the hyperpolarization-activated inward current (I h) reduces excitability of peripheral axons during stimulation and decreases ectopic discharges in axotomized sensory neurons. Changes in I h expression in DRG neurons have been suggested to partially underlie sensitization after nerve injury and inflammation. We hypothesized that peripheral block of I h on axons would produce an antiallodynic effect in postoperative as well as neuropathic conditions, and we tested perineural administration of ZD 7288, a specific blocker of I h , on pain-associated behavior in animal models of neuropathic and postoperative pain.Methods: Under halothane anesthesia, partial sciatic nerve injury or hind-paw incision were performed on adult male rats as previously described. Mechanical allodynia was inferred by demonstration of a decrease in paw withdrawal threshold by application of calibrated von Frey filaments. After surgery, animals received either a saline or a ZD 7288 solution either by sciatic perineural injection or by intraplantar injection.Results: Perineural administration of ZD 7288 (100 microM) significantly reduced mechanical allodynia induced by partial sciatic nerve injury and hind-paw incision. Saline and 10 microM of ZD 7288 had no significant effect on mechanical allodynia. Contralateral administration of ZD 7288, 100 microM, did not affect ipsilateral paw withdrawal threshold after nerve injury. Intraplantar injection of ZD 7288 failed to reduce mechanical allodynia after nerve injury. Sedation and motor effects were not observed.Conclusions: The current study shows that peripheral block of I h produces an antiallodynic effect, which suggests that I h channels represent a novel target for nerve block treatment of postoperative and neuropathic pain. [ABSTRACT FROM AUTHOR]

A numerical frequency-domain modelling of two-terminal, non-linear microwave circuits is presented. It basically relies on a process allowing the solution of the frequency-domain circuit harmonic balance equations while accounting for the semiconductor device by means of an accurate numerical macroscopic physical model. In its present state of development, the model allows the study of a single two-terminal device circuit operating in harmonic mode. Its capabilities are illustrated by means of the results of a study devoted to the optimization of the load circuit configuration of a millimetre-wave avalanche diode frequency multiplier. The influence of the output load impedance level on the circuit output RF performance has been investigated for different input power levels in direct frequency multiplication mode and in the presence of additional circuit tunings at low harmonic rank idler frequencies. [ABSTRACT FROM AUTHOR]

A numerical time-domain modelling of non-linear microwave circuits is presented. It is based on a numerical procedure allowing the solution of the integro-differential equation driving the instantaneous electrical behaviour of a lumped-element circuit while accounting for the semiconductor device by means of an accurate numerical macroscopic model. This modelling is firstly validated by studying the DC turn-on and DC forward-reverse commutation of a PIN diode. The diode voltage and current waveform are qualitatively consistent with experimental ones. Moreover, the predicted recovery time values are found to be in good agreement with those issued from the classical analytical theory. Secondly, in order to illustrate the present capabilities of the model, the whole transient response of a back-to-back silicon PIN diode passive power limiter to a high-input-RF-power pulse is described. It is demonstrated that in the present case of a 2 p.m- long PIN diode, the high-input-power steady-state operation only relies on one diode. To our knowledge, it is the first time this kind of simulation is applied to a two-diode circuit. [ABSTRACT FROM AUTHOR]

A new P-N junction device model is presented. It consists of two numerical un-idimensional macroscopic models. The first is a drift-diffusion model. The second is an energy model accounting for the carrier energy relaxation effects. Because device optimization requires systematic investigations, the computing time is of paramount importance and, so an accurate comparison between these two models was undertaken under both static steady-state and dynamic 94 GHz conditions in order to point out the relative interest of the energy model. This study is mainly devoted to silicon millimetre-wave IMPATFs. This comparison has highlighted the superiority of the energy model for the description of low field transport phenomena. But as IMPA1T RF properties are mainly governed by high field transport, the RF power levels predicted by the two models have been found to be similar. Moreover it has shown that the energy model tends to underestimate both the efficiency and the diode terminal negative resistance level. This parasitic effect is inherent to the description of the carrier generation process by impact ionization which in this model is assumed to be governed by the carrier energy. [ABSTRACT FROM AUTHOR]

This letter describes the analysis of GaN Gunn oscillations by means of a physical-thermal modeling based on the coupling of an energy-balance model for the description of electron transport in the active area with a thermal model for the description of the lattice temperature everywhere in the device. The most important aspect of the model is the possibility to take into account the local temperature at each point of the device and its influence on transport properties. Electric behaviors (static and microwave characterizations), as well as thermal behaviors are described, thus making it possible to optimize the device. [ABSTRACT FROM AUTHOR]

Abstract Background RT-PCR has been widely used for the analysis of gene expression in many systems, including tumor samples. GAPDH (Glyceraldehyde-3-phosphate dehydrogenase) has been frequently considered as a constitutive housekeeping gene and used to normalize changes in specific gene expression. However, GAPDH has been shown to be up-regulated in many cancers and down-regulated by chemotherapic drugs. Bisphosphonates, potent inhibitors of bone resorption, have recently shown a direct and indirect antitumor effect in vitro and in animal models. They exert their effects mainly by inhibiting the mevalonate pathway but also by modulating the expression of many genes not only in osteoclasts but also in cancer cells. Methods We evaluated GAPDH gene expression by real time RT PCR in breast (MCF-7 and T47D) and prostate (PC3 and DU-145) cancer cell lines treated with amino and non-amino bisphosphonates. Results Our results showed that amino-bisphosphonates significantly decrease in a dose-dependent manner the expression of GAPDH gene. Conclusion Therefore, GAPDH is inaccurate to normalize mRNA levels in studies investigating the effect of bisphosphonates on gene expression and it should be avoided. On the other hand, this gene could be considered a potential target to observe the effects of bisphosphonates on cancer cells.