Amino acid substitution during functionally constrained divergent evolution of protein sequences

In aligning homologous protein sequences, it is generally assumed that amino acid substitutions subsequent in time occur independently of amino acid substitutions previous in time, i.e. that patterns of mulation are similar at low and high sequence divergence. This assumption is examined here and shown to be incorrect in an interesting way. Separate mutation matrices were constructed for aligned protein sequence pairs at divergences ranging from 5 to 100 PAM units (point accepted mutations per 100 aligned positions). From these, the corresponding log-odds (Day-hoff) matrices, normalized to 250 PAM units, were constructed. The matrices show that the genetic code influences accepted point mutations strongly at early stages of divergence, while the chemical properties of the side chains dominate at more advanced stage

Distribution of sound pressure around a singing cricket: radiation pattern and asymmetry in the sound field

Male field crickets generate calls to attract distant females through tegminal stridulation: the rubbing together of the overlying right wing which bears a file of cuticular teeth against the underlying left wing which carries a sclerotised scraper. During stridulation, specialised areas of membrane on both wings are set into oscillating vibrations to produce acoustic radiation. The location of females is unknown to the calling males and thus increasing effective signal range in all directions will maximise transmission effectiveness. However, producing an omnidirectional sound field of high sound pressure levels may be problematic due to the mechanical asymmetry found in this sound generation system. Mechanical asymmetry occurs by the right wing coming to partially cover the left wing during the closing stroke phase of stridulation. As such, it is hypothesised that the sound field on the left-wing side of the animal will contain lower sound pressure components than on the right-wing side as a result of this coverage. This hypothesis was tested using a novel method to accurately record a high resolution, three dimensional mapping of sound pressure levels around restrained Gryllus bimaculatus field crickets singing under pharmacological stimulation. The results indicate that a bilateral asymmetry is present across individuals, with greater amplitude components present in the right wing side of the animal. Individual variation in sound pressure to either the right or left-wing side is also observed. However, statistically significant differences in bilateral sound field asymmetry as presented here may not affect signalling in the field

Present status of perch fishery resources in India and its prospects

The perch resources and fisheries In India have been dealt with. As seen from the statewise perch production during 1969-19Q1, on an average 27,184 tonnes of parches were landed in India with fluctuation from 12,865 In 1969 to 49,312 in 1978. The gearwise and statewise perch production from 1982-83 to 1984-85 indicates that the mechanised units contributed 72.4 % and nonmechanised 27.6 %. Among mechanised units, the trawlers have landed the major portion of the catch (68 4 % ) . The State wise species composition of perch landings indicate that the threadtin breams formed more than 50% of the catch- During 1982-83 and 1S83-84. the perch production of Tamil Nadu was higher than all other states whereas during 1984 85, Kerala was the first in perch production followed by Andhrapradesh and Tamil Nadu- The different groups of perches landed by trawl and gill net units at different important landing centres on the east and west coast of Indian show that in all the centres the catch rates of trawlers were higher. The higher catch rate in trawl net operations In Sasoons Dock and New ferry Wharf was due to voyage fishing for more than a da

Marine fish calendar. 6. Tuticorin

Tuticorin is one of the well known, age old, fishery ports of India especially by virtue of the production of valuable, good quality, natural pearls and chanks in addition to marine fish production. Early in the 19I1-'15 periods the marine fish production here was to the tune of 663,592 pounds (296.3 tonnes). The fishermen strength was 520 who operated conventional 'valavalai', 'kolavalai', 'madivalai', offshore lining, inshore lining, trolling and other minor nets with the traditional fishing crafts like Tuticorin type of plank built boats called 'Vallam' and 'catamarans'. Over the two decades, mechanized fishing has changed not only the fishing pattern but also the constituent catches. The progress of fishing industry can still be augmented by motorising the plank built boats and 'catamarans'. Present assessment of fishery resources reveals that in a year 19,850 t of fish are landed by trawlers and 9,275 t by traditional fishing units

Geometry of the 3-Qubit State, Entanglement and Division Algebras

We present a generalization to 3-qubits of the standard Bloch sphere representation for a single qubit and of the 7-dimensional sphere representation for 2 qubits presented in Mosseri {\it et al.}\cite{Mosseri2001}. The Hilbert space of the 3-qubit system is the 15-dimensional sphere $S^{15}$, which allows for a natural (last) Hopf fibration with $S^8$ as base and $S^7$ as fiber. A striking feature is, as in the case of 1 and 2 qubits, that the map is entanglement sensitive, and the two distinct ways of un-entangling 3 qubits are naturally related to the Hopf map. We define a quantity that measures the degree of entanglement of the 3-qubit state. Conjectures on the possibility to generalize the construction for higher qubit states are also discussed.Comment: 12 pages, 2 figures, final versio

Quantum Cryptography Based on the Time--Energy Uncertainty Relation

A new cryptosystem based on the fundamental time--energy uncertainty relation is proposed. Such a cryptosystem can be implemented with both correlated photon pairs and single photon states.Comment: 5 pages, LaTex, no figure

Digging the optimum pit: Antlions, spirals and spontaneous stratification

Most animal traps are constructed from self-secreted silk, so antlions are rare among trap builders because they use only materials found in the environment. We show how antlions exploit the properties of the substrate to produce very effective structures in the minimum amount of time. Our modelling demonstrates how antlions: (i) exploit self-stratification in granular media differentially to expose deleterious large grains at the bottom of the construction trench where they can be ejected preferentially, and (ii) minimize completion time by spiral rather than central digging. Both phenomena are confirmed by our experiments. Spiral digging saves time because it enables the antlion to eject material initially from the periphery of the pit where it is less likely to topple back into the centre. As a result, antlions can produce their pits—lined almost exclusively with small slippery grains to maximize powerful avalanches and hence prey capture—much more quickly than if they simply dig at the pit’s centre. Our demonstration, for the first time to our knowledge, of an animal using self-stratification in granular media exemplifies the sophistication of extended phenotypes even if they are only formed from material found in the animal’s environment

Entangled photon pairs produced by a quantum dot strongly coupled to a microcavity

We show theoretically that entangled photon pairs can be produced on demand through the biexciton decay of a quantum dot strongly coupled to the modes of a photonic crystal. The strong coupling allows to tune the energy of the mixed exciton-photon (polariton) eigenmodes, and to overcome the natural splitting existing between the exciton states coupled with different linear polarizations of light. Polariton states are moreover well protected against dephasing due to their lifetime ten to hundred times shorter than that of a bare exciton. Our analysis shows that the scheme proposed can be achievable with the present technology

Environment and classical channels in categorical quantum mechanics

We present a both simple and comprehensive graphical calculus for quantum computing. In particular, we axiomatize the notion of an environment, which together with the earlier introduced axiomatic notion of classical structure enables us to define classical channels, quantum measurements and classical control. If we moreover adjoin the earlier introduced axiomatic notion of complementarity, we obtain sufficient structural power for constructive representation and correctness derivation of typical quantum informatic protocols.Comment: 26 pages, many pics; this third version has substantially more explanations than previous ones; Journal reference is of short 14 page version; Proceedings of the 19th EACSL Annual Conference on Computer Science Logic (CSL), Lecture Notes in Computer Science 6247, Springer-Verlag (2010

Multiphoton localization and propagating quantum gap solitons in a frequency gap medium

The many-particle spectrum of an isotropic frequency gap medium doped with impurity resonance atoms is studied using the Bethe ansatz technique. The spectrum is shown to contain pairs of quantum correlated ``gap excitations'' and their heavy bound complexes (``gap solitons''), enabling the propagation of quantum information within the classically forbidden gap. In addition, multiparticle localization of the radiation and the medium polarization occurs when such a gap soliton is pinned to the impurity atom.Comment: 8 pages, RevTEX, to appear in Phys. Rev. Let