DSIM: A distributed simulator

Discrete event-driven simulation makes it possible to model a computer system in detail. However, such simulation models can require a significant time to execute. This is especially true when modeling large parallel or distributed systems containing many processors and a complex communication network. One solution is to distribute the simulation over several processors. If enough parallelism is achieved, large simulation models can be efficiently executed. This study proposes a distributed simulator called DSIM which can run on various architectures. A simulated test environment is used to verify and characterize the performance of DSIM. The results of the experiments indicate that speedup is application-dependent and, in DSIM's case, is also dependent on how the simulation model is distributed among the processors. Furthermore, the experiments reveal that the communication overhead of ethernet-based distributed systems makes it difficult to achieve reasonable speedup unless the simulation model is computation bound

Ge growth on ion-irradiated Si self-affine fractal surfaces

We have carried out scanning tunneling microscopy experiments under ultrahigh vacuum condition to study the morphology of ultrathin Ge films eposited on pristine Si(100) and ion-irradiated Si(100) self-affine fractal surfaces. The pristine and the ion-irradiated Si(100) surface have roughness exponents of alpha=0.19+/-0.05 and alpha=0.82+/-0.04 respectively. These measurements were carried out on two halves of the same sample where only one half was ion-irradiated. Following deposition of a thin film of Ge (~6 A) the roughness exponents change to 0.11+/-0.04 and 0.99+/-0.06, respectively. Upon Ge deposition, while the roughness increases by more than an order of magnitude on the pristine surface, a smoothing is observed for the ion-irradiated surface. For the ion-irradiated surface the correlation length xi increases from 32 nm to 137 nm upon Ge deposition. Ge grows on Si surfaces in the Stranski-Krastanov or layer-plus-island mode where islands grow on a wetting layer of about three atomic layers. On the pristine surface the islands are predominantly of square or rectangular shape, while on the ion-irradiated surface the islands are nearly diamond shaped. Changes of adsorption behaviour of deposited atoms depending on the roughness exponent (or the fractal dimension) of the substrate surface are discussed.Comment: 5 pages, 2 figures and 1 tabl

Optimal L2-error estimates for the semidiscrete Galerkin\ud approximation to a second order linear parabolic initial and\ud boundary value problem with nonsmooth initial data

In this article, we have discussed a priori error estimate for the semidiscrete Galerkin approximation of a general second order parabolic initial and boundary value problem with non-smooth initial data. Our analysis is based on an elementary energy argument without resorting to parabolic duality technique. The proposed technique is also extended to a semidiscrete mixed method for parabolic problems. Optimal L2-error estimate is derived for both cases, when the initial data is in L2

Backward Euler method for the Equations of Motion Arising in Oldroyd Fluids of Order One with Nonsmooth Initial Data

In this paper, a backward Euler method is discussed for the equations of motion arising in the 2D Oldroyd model of viscoelastic fluids of order one with the forcing term independent of time or in $L^{\infty}$ in time. It is shown that the estimates of the discrete solution in Dirichlet norm is bounded uniformly in time. Optimal a priori error estimate in L2-norm is derived for the discrete problem with non-smooth initial data. This estimate is shown to be uniform in time, under the assumption of uniqueness condition

RNA Vaccine: novel approach for cancer treatment

Cancer is still an unsolved puzzle and a major cause of mortality and morbidity in the world. Today, about one in every thousand people is dying due to cancer. No effective agent has yet been found which can cure cancer in its metastatic stage. However, attempts in the shape of chemotherapy, immunotherapy and vaccines are made worldwide to find a remedy through a proper regimen. In continuation, tumor specific mRNA has been introduced as part of vaccines in recent days. It is mostly used in transfection with Dendritic Cells (DCs) for better effectiveness and safety. The DCs are selected for transfection because they are highly potent Antigen Presenting Cells (APCs) with the ability to take up & process tumor antigen in peripheral blood & tissues and can also migrate to the draining lymph nodes to present antigen to naïve T lymphocytes & induce the immune response.
Although initially the RNA vaccination was administered alone, due to its unstable and easily degradable nature, it was found to be quite less effective, which led it to be used in combination with some stability enhancers’ viz. RNA packaging in liposomes. They not only increased its stability, but even worked as active immune stimulators as well. RNA could remain stable. Although it showed significant promise in cancer treatment, immune suppression was noticed after vaccination. To enhance the effectiveness it is now being used in combination with few drugs viz. SUNITINIB which can reduce the suppressive effect of suppressor cells. It might be a good choice for combined therapy with RNA vaccine.
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