Coupling Between Helix-Coil and Coil-Globule Transitions in Helical Polymers

We explore the coupling between the helix-coil and coil-globule transitions of a helical polymer using Monte Carlo simulations. A very rich state diagram is found. Each state is characterized by a specific configuration of the chain which could be a helix, a random coil, an amorphous globule, or one of various other globular states which carry residual helical strands. We study the boundaries between states and provide further insight into the physics of the system with a detailed analysis of the order parameter and other properties

High frequency induction of somatic embryos and plantlet regeneration from nodal explants of Hygrophila spinosa T. Anders

An efficient protocol is described for the rapid in vitro plant regeneration of a medicinally important plant, Hygrophila spinosa through direct somatic embryogenesis from nodal explants excised from 4 week old aseptic seedlings. Somatic embryos differentiated directly from nodal explants on Murashige and Skoog (MS) medium supplemented with 1.0 ìM 6- benzyladenine (BA) after 1 week of culture. The highest number (110.40 ± 3.55) of somatic embryos were recorded on MS medium supplemented with 1.0 ìM BA and 0.5 ìM NAA, growth regulator free half strength MS medium was found suitable for maturation and conversion of somatic embryos into complete plantlets. The well developed in vitro regenerated plantlets were successfully established in pots containing garden soil and grown in agreenhouse with 85% survival rate. The regenerants present an appearance similar to the seedlings obtained from normal seeds. The described method can be successfully employed for large scale multiplication and long term in vitro conservation of H. spinosa

How Does the Coupling of Secondary and Tertiary Interactions Control the Folding of Helical Macromolecules?

The authors study how the simultaneous presence of short-range secondary and long-range tertiary interactions controls the folding and collapse behavior of a helical macromolecule. The secondary interactions stabilize the helical conformation of the chain, while the tertiary interactions govern its overall three-dimensional shape. The authors have carried out Monte Carlo simulations to study the effect of chain length on the folding and collapse behavior of the chain. They have calculated state diagrams for four chain lengths and found that the physics is very rich with a plethora of stable conformational states. In addition to the helix-coil and coil-globule transitions, their model describes the coupling between them which takes place at low temperatures. Under these conditions, their model predicts a cascade of continuous, conformational transitions between states with an increase in the strength of the tertiary interactions. During each transition the chain shrinks, i.e., collapses, in a rapid and specific manner. In addition, the number of the transitions increases with increasing chain length. They have also found that the low-temperature regions of the state diagram between the transition lines cannot be associated with specific structures of the chain, but rather, with ensembles of various configurations of the chain with similar characteristics. Based on these results the authors propose a mechanism for the folding and collapse of helical macromolecules which is further supported by the analysis of configurational, configurational, and thermodynamic properties of the chain

Geo-Skip List Data Structure ? Implementation and Solving Spatial Queries

A major portion of the queries fired on the internet have spatial keywords in them, the storage and retrieval of spatial data has become an important task in today?s era. Given a geographic query that is composed of query keywords and a location, a geographic search engine retrieves documents that are the most textually and spatially relevant to the query keywords and the location, respectively, and ranks the retrieved documents according to their joint textual and spatial relevance to the query. The lack of an efficient index that can simultaneously handle both the textual and spatial aspects of the documents makes existing geographic search engines inefficient in answering geographic queries. There are data structures which facilitate storage and retrieval of geographical data like R-trees, R* trees, KD trees etc. We propose Geo-Skip list data structure which is also one such data structure which is inspired from the skip list data structure. It is simple, dynamic, partly deterministic and partly randomized data structure. This structure brings out the hierarchy of administrative divisions of a region very well. Also it shows an improvement in the search efficiency as compared with R-trees. In this paper, we propose algorithms for the implementation of basic spatial queries with the help of Geo-Skip List data structure ? namely, point query, range query, finding the nearest neighbour query and kth nearest neighbour query