Dynamics of Diblock Copolymers in Dilute Solutions

We consider the dynamics of freely translating and rotating diblock (A-B), Gaussian copolymers, in dilute solutions. Using the multiple scattering technique, we have computed the diffusion and the friction coefficients D_AB and Zeta_AB, and the change Eta_AB in the viscosity of the solution as functions of x = N_A/N and t = l_B/l_A, where N_A, N are the number of segments of the A block and of the whole copolymer, respectively, and l_A, l_B are the Kuhn lengths of the A and B blocks. Specific regimes that maximize the efficiency of separation of copolymers with distinct "t" values, have been identified.Comment: 20 pages Revtex, 7 eps figures, needs epsf.tex and amssymb.sty, submitted to Macromolecule

Simulation of structural and electronic properties of amorphous tungsten oxycarbides

Electron beam induced deposition with tungsten hexacarbonyl W(CO)6 as precursors leads to granular deposits with varying compositions of tungsten, carbon and oxygen. Depending on the deposition conditions, the deposits are insulating or metallic. We employ an evolutionary algorithm to predict the crystal structures starting from a series of chemical compositions that were determined experimentally. We show that this method leads to better structures than structural relaxation based on guessed initial structures. We approximate the expected amorphous structures by reasonably large unit cells that can accommodate local structural environments that resemble the true amorphous structure. Our predicted structures show an insulator to metal transition close to the experimental composition at which this transition is actually observed. Our predicted structures also allow comparison to experimental electron diffraction patterns.Comment: 17 Pages, 11 figure

THERAPEUTIC EFFECTIVENESS OF A SIDDHA FORMULATION NILAVAAGAI CHOORANAM: A REVIEW

Siddha system of medicine is one of the ancient systems of medicine practiced among Tamil speaking community particularly in southern parts of India. The medicine in this system prepared from raw drugs which is obtained from herbals, mineral, metals and animal products. “Nilavaagaichooranam” is one of the Sastric Siddha herbo-mineral preparation with ingredients of 18 herbal and one mineral ingredient. It is used to treat the skin disorders particularly for “Karappan (Eczema)”. This review is aimed to bring out scientific evidence for the therapeutic usuage of “Nilavaagaichooranam” in skin disorders particularly in Karappan (Eczema) and focused on the pharmacological activity responsible for the curative nature of the drug in Karappan (Eczema). Most of the raw drugs used for the preparation of Nilavaagai chooranam have antihistamine activity, anti-inflammatory activity, immunomodulatory activity hence justifying its usage in Karappan (Eczema)

What drives the translocation of stiff chains?

We study the dynamics of the passage of a stiff chain through a pore into a cell containing particles that bind reversibly to it. Using Brownian Molecular Dynamics simulations we investigate the mean-first-passage time as a function of the length of the chain inside, for different concentrations of binding particles. As a consequence of the interactions with these particles, the chain experiences a net force along its length whose calculated value from the simulations accounts for the velocity at which it enters the cell. This force can in turn be obtained from the solution of a generalized diffusion equation incorporating an effective Langmuir adsorption free energy for the chain plus binding particles. These results suggest a role of binding particles in the translocation process which is in general quite different from that of a Brownian ratchet. Furthermore, non-equilibrium effects contribute significantly to the dynamics, \emph{e.g.}, the chain often enters the cell faster than particle binding can be saturated, resulting in a force several times smaller than the equilibrium value.Comment: 7 pages, 4 figure

ATTAI VIDAL (LEECH THERAPY) IN SIDDHA SYSTEM OF MEDICINE AND THEIR CURRENT CONCEPT IN THERAPEUTIC APPLICATION - A REVIEW

The Siddha system of medicine is an unique traditional system of medicine practiced in Tamil speaking countries particularly India. In Siddha system of medicine the diseases were treated through internal and external medicine. In external medicine, the leech therapy is one which is used to treat various non-surgical and surgical cases. The leeches have been used for therapeutic purposes since their beginning of civilisation. Ancient Indian, Egyptian, Greek and Arab physicians were used the leeches for wide range of diseases such as inflammatory condition, skin diseases, respiratory disorders, eye diseases, cardiac diseases, urinary and reproductive diseases and dental diseases. The leeches are also used as one of the bloodletting methods in Unani, Ayurveda, and Modern science for various clinical conditions. Recently, researches on leech saliva revealed the presence nearly 100 biologically active compounds such as Hirudin, vasodilators, hyaluronidase, anaesthetics, fibrinases, antibacterial, collagenase etc. The above mentioned pharmacological compounds are injected into human body while sucking of the blood and are responsible for the anaesthetic, anti-inflammatory, anticoagulant and analgesic effect of leech application. In current scenario, the leech therapy is used for various diseases including life threatening diseases such as cardiovascular diseases, cancer, etc. in different system of medicine including modern medicine. Leech therapy is used in plastic and microsurgery as a protective tool against vascular congestion in modern medicine. The Scientific studies on leech saliva were proven and support the leech application in Siddha system of medicine

Mycorrhizae in sedges as related to root character and its ecological significance

Twenty four sedges were examined to assess the role of root characters on mycorrhizal status. Vesicular-arbuscular mycorrhizal (VAM) injection was positively related to root thickness and negatively to root hair number and length. Dried mycorrhizal roots of Bulbostylis barbata, Cyperus cyperinus. C. kyllingia and Fimbristylis ovata served as inocula oj VAMJungi in pot culture study indicating that mycorrhizal sedge roots could act as inocula in initiating and reviving mycorrhizae in natural soils

An overview of the ciao multiparadigm language and program development environment and its design philosophy

We describe some of the novel aspects and motivations behind the design and implementation of the Ciao multiparadigm programming system. An important aspect of Ciao is that it provides the programmer with a large number of useful features from different programming paradigms and styles, and that the use of each of these features can be turned on and off at will for each program module. Thus, a given module may be using e.g. higher order functions and constraints, while another module may be using objects, predicates, and concurrency. Furthermore, the language is designed to be extensible in a simple and modular way. Another important aspect of Ciao is its programming environment, which provides a powerful preprocessor (with an associated assertion language) capable of statically finding non-trivial bugs, verifying that programs comply with specifications, and performing many types of program optimizations. Such optimizations produce code that is highly competitive with other dynamic languages or, when the highest levéis of optimization are used, even that of static languages, all while retaining the interactive development environment of a dynamic language. The environment also includes a powerful auto-documenter. The paper provides an informal overview of the language and program development environment. It aims at illustrating the design philosophy rather than at being exhaustive, which would be impossible in the format of a paper, pointing instead to the existing literature on the system

Simple Exactly Solvable Models of non-Fermi Liquids

We generalize the model of Hatsugai and Kohmoto [J. Phys. Soc. Jpn, 61, 2056 (1992)] and find ground states which do not show the properties of Fermi liquids. We work in two space dimensions, but it is straightforward to generalize to higher dimensions. The ground state is highly degenerate and there is no discontinuity in the momentum distribution; i.e., there is no Fermi surface. The Green's function generically has a branch cut.Comment: Revte

Anomalous Dynamics of Translocation

We study the dynamics of the passage of a polymer through a membrane pore (translocation), focusing on the scaling properties with the number of monomers $N$. The natural coordinate for translocation is the number of monomers on one side of the hole at a given time. Commonly used models which assume Brownian dynamics for this variable predict a mean (unforced) passage time $\tau$ that scales as $N^2$, even in the presence of an entropic barrier. However, the time it takes for a free polymer to diffuse a distance of the order of its radius by Rouse dynamics scales with an exponent larger than 2, and this should provide a lower bound to the translocation time. To resolve this discrepancy, we perform numerical simulations with Rouse dynamics for both phantom (in space dimensions $d=1$ and 2), and self-avoiding (in $d=2$) chains. The results indicate that for large $N$, translocation times scale in the same manner as diffusion times, but with a larger prefactor that depends on the size of the hole. Such scaling implies anomalous dynamics for the translocation process. In particular, the fluctuations in the monomer number at the hole are predicted to be non-diffusive at short times, while the average pulling velocity of the polymer in the presence of a chemical potential difference is predicted to depend on $N$.Comment: 9 pages, 9 figures. Submitted to Physical Review