The larval stages of Periclimenes (Periclimenes) Indicus Kemp

Larva of several species of Periclimenes have been described before; but all of them belong to the subgenus Ancylocaris. Periclimenes indicus Kemp comes under the subgenus Periclimenes (Kemp, 1922), and an account of its larvre should not be without interest, as it would serve to bring out the differences among the larvre of a genus whose species are so numerous and so diverse in habit

Molecular emission near metal interfaces: the polaritonic regime

The strong coupling of a dense layer of molecular excitons with surface-plasmon modes in a metal gives rise to polaritons (hybrid light-matter states) called plexcitons. Surface plasmons cannot directly emit into (or be excited by) free-space photons due to the fact that energy and momentum conservation cannot be simultaneously satisfied in photoluminescence. Most plexcitons are also formally non-emissive, even though they can radiate via molecules upon localization due to disorder and decoherence. However, a fraction of them are bright even in the presence of such deleterious processes. In this letter, we theoretically discuss the superradiant emission properties of these bright plexcitons, which belong to the upper energy branch and reveal huge photoluminescence enhancements compared to bare excitons. Our study generalizes the well-known problem of molecular emission next to a metal interface to collective molecular states and provides new design principles for the control of photophysical properties of molecular aggregates using polaritonic strategies.Comment: Replaced previous version, noticing that van Hove anomalies are only observed in the direct and reflected contributions of photoluminescence, but they cancel out when added up in the total photoluminescence. The correct phenomenology is that enhancements of photoluminescence are still huge (not infinite) and are near (not exactly at) the critical poin

A Note on the Bionomics and Fishery of the Swimming Crab Neptunus sanguinolenlus (Herbst) on the Malabar Coast

Large numbers of the swimming crab Neptumts sanguinolentus are caught and marketed at Kozhikode and the neighbouring places on the West Coast of the Madras State from January to April or.May. It has been obtained in fairly good numbers during these months in the regular departmental catches of fish. Two other species also, N. pelagicus (Linn.) and Charybdis natator (Herbst) have been captured sporadically; but they were always few and did not make any appreciable contribution to the crab fishery at this place during the seasons of 1950 and 1951

Contributions to the biology of penaeid prawns of the south-west coast of India I. Sex ratio and movements

The biology and fishery of Indian Penaeid prawns of commercial importance particularly of the south-west coast, are being studied in detail by the Central Marine Fisheries Research Station and some of the results obtained so far have been already published (Menon 1951, 1953, 1954, 1955 and Panikkar and Menon, 1955). The present contribution deals with the sex ratio at successive stages of life in four species, namely, Metapenceus dobsoni, Pentms indicus, Metapenceus affinis and Parapemeopsis stylifera. Some observations on this aspect in relation to M. dobsoni have been included in the second of the two, papers dealing with its biology (1955). The discovery of the wide disparity in the proportion of the sexes in the third year of life of this species provided the incentive for a more extensive study of the problem in the same species as well as in three other species also

On the paddy field prawn fishery of Travancore-Cochin and an experiment in prawn culture

The extensive paddy fields on both sides of the backwaters and many of the connected canals in tt the northern ports of the Travancore-Cochin State, which are single crop lands, have been used for the past several decades for prawn fishing

Observations on the prawn fishery of the Cochin backwaters with special reference to the stake net catches

The long chain of backwaters extending along the central and southern parts of the Kerala State provides rich prawn fishing grounds, where fishing is carried out practically all the year round. The fishery is not confined to the backwaters only, but extends into the extensive networks of canals connected with them and also to the paddy fields bordering the' Vembanad Kayal' at about the middle of the chain. Though reliable statistics are y~t lacking there is little doubt that the annual production may amount to several' thousands of tons

The Nuclear Activity of the Galaxies in the Hickson Compact Groups

In order to investigate the nuclear activity of galaxies residing in compact groups of galaxies, we present results of our optical spectroscopic program made at Okayama Astrophysical Observatory. We have performed optical spectroscopy of 69 galaxies which belong to 31 Hickson Compact Groups (HCGs) of Galaxies. Among them, three galaxies have discordant redshifts. Further, spectral quality is too poor to classify other three galaxies. Therefore, we describe our results for the remaining 63 galaxies. Our main results are summarized below. (1) We have found in our sample; 28 AGN, 16 HII nuclei, and 19 normal galaxies which show no emission line. We used this HCG sample for statistical analyses. (2) Comparing the frequency distributions of activity types between the HCGs and the field galaxies whose data are taken from Ho, Filippenko, & Sargent (382 field galaxies), we find that the frequency of HII nuclei in the HCGs is significantly less than that in the field. However, this difference may be due to selection bias that our HCG sample contains more early-type galaxies than the field, because it is known that HII nuclei are rarer in early-type galaxies than in later ones. (3) Applying correction this morphological bias to the HCG sample, we find that there is no statistically significant difference in the frequency of occurrence of emission-line galaxies between the HCGs and the field. This implies that the dense galaxy environment in the HCGs does not affect triggering both the AGN activity and the nuclear starburst. We discuss some implications on the nuclear activity in the HCG galaxies.Comment: 33 pages (3 aasms4 LaTeX files), 5 figures (5 Postscript files: excluded Figure 1), Accepted for publication in The Astronomical Journa

Nonlinear maneuver autopilot for the F-15 aircraft

A methodology is described for the development of flight test trajectory control laws based on singular perturbation methodology and nonlinear dynamic modeling. The control design methodology is applied to a detailed nonlinear six degree-of-freedom simulation of the F-15 and results for a level accelerations, pushover/pullup maneuver, zoom and pushover maneuver, excess thrust windup turn, constant thrust windup turn, and a constant dynamic pressure/constant load factor trajectory are presented