Stabilisation of Seven Directions in an Early Universe M -- theory Model

Our model consists of intersecting 22'55' branes in M theory distributed uniformly in the common transverse space. Equations of state follow from U duality symmetries. In this model, three spatial directions expand, and seven directions stabilise to constant sizes. From string theory perspective, the dilaton is hence stabilised. The constant sizes depend on certain imbalance among initial values. One naturally obtains M_{11} \simeq M_s \simeq M_4 and g_s \simeq 1 within a few orders of magnitude. Smaller numbers, for example M_s \simeq 10^{- 16} M_4, are also possible but require fine tuning.Comment: 11 Pagesl. Latex file. Version 2: Minor changes and a reference added. Version 3: Title changed; many textual modifications, mainly to keep within journal's length constraints, and to explain the differences between brane gas models and intersecting brane configurations used here; references added. To appear in Physical Review D (Rapid communications

10 + 1 to 3 + 1 in an Early Universe with mutually BPS Intersecting Branes

We assume that the early universe is homogeneous, anisotropic, and is dominated by the mutually BPS 22'55' intersecting branes of M theory. The spatial directions are all taken to be toroidal. Using analytical and numerical methods, we study the evolution of such an universe. We find that, asymptotically, three spatial directions expand to infinity and the remaining spatial directions reach stabilised values. Any stabilised values can be obtained by a fine tuning of initial brane densities. We give a physical description of the stabilisation mechanism. Also, from the perspective of four dimensional spacetime, the effective four dimensional Newton's constant G_4 is now time varying. Its time dependence will follow from explicit solutions. We find in the present case that, asymptotically, G_4 exhibits characteristic log periodic oscillations.Comment: Latex file, 59 pages, 7 figures. Version 2: A minor correction and a reference added. Version 3: Critical discussion of the main assumptions is added in sections I and VIII; two references added. To appear in Physical Review

Development of data store search engine for surface water pathway criteria list

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1997.Includes bibliographical references (leaf 54).by S. Rony Mukhopadyay.M.Eng

APOBEC3G Interacts with ssDNA by Two Modes: AFM Studies.

APOBEC3G (A3G) protein has antiviral activity against HIV and other pathogenic retroviruses. A3G has two domains: a catalytic C-terminal domain (CTD) that deaminates cytidine, and a N-terminal domain (NTD) that binds to ssDNA. Although abundant information exists about the biological activities of A3G protein, the interplay between sequence specific deaminase activity and A3G binding to ssDNA remains controversial. We used the topographic imaging and force spectroscopy modalities of Atomic Force Spectroscopy (AFM) to characterize the interaction of A3G protein with deaminase specific and nonspecific ssDNA substrates. AFM imaging demonstrated that A3G has elevated affinity for deaminase specific ssDNA than for nonspecific ssDNA. AFM force spectroscopy revealed two distinct binding modes by which A3G interacts with ssDNA. One mode requires sequence specificity, as demonstrated by stronger and more stable complexes with deaminase specific ssDNA than with nonspecific ssDNA. Overall these observations enforce prior studies suggesting that both domains of A3G contribute to the sequence specific binding of ssDNA