Active elastic dimers: self-propulsion and current reversal on a featureless track

We present a Brownian inchworm model of a self-propelled elastic dimer in the absence of an external potential. Nonequilibrium noise together with a stretch-dependent damping form the propulsion mechanism. Our model connects three key nonequilibrium features -- position-velocity correlations, a nonzero mean internal force, and a drift velocity. Our analytical results, including striking current reversals, compare very well with numerical simulations. The model unifies the propulsion mechanisms of DNA helicases, polar rods on a vibrated surface, crawling keratocytes and Myosin VI. We suggest experimental realizations and tests of the model.Comment: 4 page

Elastic constants from microscopic strain fluctuations

Fluctuations of the instantaneous local Lagrangian strain $\epsilon_{ij}(\bf{r},t)$, measured with respect to a static ``reference'' lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse- grained by averaging them within subsystems (of size $L_b$) of a system (of total size $L$) in the canonical ensemble. Using a simple finite size scaling theory we predict the behaviour of the fluctuations $$ as a function of $L_b/L$ and extract elastic constants of the system {\em in the thermodynamic limit} at nonzero temperature. Our method is simple to implement, efficient and general enough to be able to handle a wide class of model systems including those with singular potentials without any essential modification. We illustrate the technique by computing isothermal elastic constants of the ``soft'' and the hard disk triangular solids in two dimensions from molecular dynamics and Monte Carlo simulations. We compare our results with those from earlier simulations and density functional theory.Comment: 24 pages REVTEX, 10 .ps figures, version accepted for publication in Physical Review

Farm-economics of genetically improved carp strains in major Asian countries and carp seed price policy model

The study has conducted the micro level analysis of hatchery operators, fishseed-rearing farmers and carp farmers with respect to their socio-economic characteristics, infrastructural development, husbandry practices and economics returns, based on the survey and on-farm trial data collected by the research partners in six Asian countries, viz. Bangladesh, China, India, Indonesia, Thailand and Vietnam. The genetically-improved carp strain is economically viable and socially acceptable. The attractive profits to hatchery operators and nursery and carp farmers have created conducive environment for the dissemination of improved carp strain. Price policy models for improved strains have been developed. The premium price for fingerlings and broodstock with improved strain has been assessed. The high price of genetically-improved nuclear seed and broodstock would build self-supportive research and extension systems in the country. A business plan for Jayanti rohu has been worked out, as an example for replacement of rohu by Jayanti rohu.Livestock Production/Industries,

Study of dynamical charge fluctuations in the hadronic medium

The dynamical charge fluctuations have been studied in ultra-relativistic heavy-ion collisions by using hadronic model simulations, such as UrQMD and HIJING. The evolution of fluctuations has been calculated at different time steps during the collision as well as different observation window in pseudorapidity (\DelEta). The final state effects on the fluctuations have been investigated by varying $\bigtriangleup\eta$~ and the time steps with the aim of obtaining an optimum observation window for capturing maximum fluctuations. It is found that $\bigtriangleup\eta$~ between 2.0 and 3.5 gives the best coverage for the fluctuations studies. The results of these model calculations for Au+Au collisions at $\sqrt{s_{\rm NN}}$~=~7.7 to 200~GeV and for Pb+Pb collisions at 2.76 TeV are presented and compared with available experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).Comment: 6 pages, 4 Figure

Spawning biology of the skipjack, Katsuwonus pelamis (Linnaeus) from Minicoy waters

One of the important technical approaches to investigate the resource characteristics of oceanic species of tunas is to study the phases of its life history. Subsequent to the results of investigations on spawning of skipjack in Minicoy waters by Raju (1964), there is no further information available on this aspect from the area. The present paper deals with the spawning of skipjack, Katsuwonus pelamis in Minicoy waters with particular reference to the reproductive process. Ova diameter measurements have been used to demonstrate the developmental changes that take place in the female gonads during the breeding season

Biology of the bait fishes Spratelloides delicatulvs (Bennet) and S. Japonicus (Houttuyn) from Minicoy waters

Spratelloides delicatulus is considered to be an excellent bait fish by Hawaiian fishermen (June 1951, Ikehara 1953, June and Reintjes 1953). This species, however, does not contribute to a good percentage of the bait\ud fish catch in Hawaii but whenever Stolephorus purpureus is not available as bait sufficiently, sprats are captured and made use as bait (Welsh 1950). S. delicatulus is the widely used sprat in the Indo-Pacific. Its poor survival in captivity is the main handicap (Ikehara 1953, June and Reintjes 1953, Wilson 1971, Lee 1973). Occurrence of this species is very seasonal in the Pacific Ocean and is available more during summer months (Welsh 1950, June 1951 Wilson 1963). Hida (1971) noted that S. delicatulus was abundant in lagoons of large atolls in Micronesia

Primjene teorije grafova: topologijski modeli za predvi|anje CDK-1 inhibicijske aktivnosti aloizina

Relationship between the topological indices and cyclin-dependent kinase-1 (CDK-1/cyclin B) inhibitory activity of 6-phenyl[5H]pyrrolo[2,3-b]pyrazines (aloisines) was investigated. Three topological indices – the Wiener Index, a distance-based topological descriptor, the Zagreb group parameter, an adjacency based topological descriptor, and the eccentric connectivity index, an adjacency-cum-distance based topological descriptor were used in the study. A data set comprising 51 analogues of aloisine was selected for the present study. Values of the Wiener index, the Zagreb group parameter and the eccentric connectivity index for each of the 51 analogues included in the data set were computed using an in-house computer program. Resultant data was analyzed and suitable models were developed after identification of active ranges. A biological activity was then assigned to each compound using these models, which was then compared with the reported CDK-1 inhibitory activity. Accuracy of prediction using these models was found to vary from a minimum of ≈82 % to a maximum of 84 %. .Istraživan je odnos izmđ|u topologijskih indeksa i CDK-1 inhibicijske aktivnosti 5-fenil[5H]pirolo[2,3-b]- pirazina (aloizina). Upotrebljena su tri topologijska indeksa: Wienerov indeks, zagrebački indeks i ekscentrični indeks povezanosti, koji su izračunani za 51 aloizin. Dobiveni modeli predviđaju inhibijsku aktivnosti aloizina s točnošću od 82–84 %