The food and feeding habit of Penaeus monodon Fabricius collected from Makato River, Aklan, Philippines

The food of Penaeus monodon collected from Makato R., from Sept 1977 to Jan 1978 is described with preliminary observations on its feeding habit and rate of foregut clearance. Feeding behaviour appears to be associated with the tidal phase. Foregut clearance rate is rapid, with 95% of food transported from the foregut 4 h after feeding. Frequency of occurrence and proportion of total food of various foregut contents are shown, as are dry weight, percentage mineral, organic and crude protein nitrogen from individual and pooled samples of gut contents, and foregut index in P. monodon collected during different phases of one tidal cycle

Research activities and accomplishments of the SEAFDEC Aquaculture Department, 1988-1991

Research studies conducted from 1988 to 1991 focused on breeding, seed production, and farming of thirteen aquaculture species of regional importance. Studies aimed at developing economical feeds, as well as disease prevention and control were undertaken. Guided by the recommendations of ADSEA I (Seminar-Workshop on Aquaculture Development in Southeast Asia; 8-12 Sept. 1987; Iloilo City, Philippines), workshops to review the previous years' progress and identify specific studies for implementation were held annually since 1989 with the participation of academic institutions, government and private sectors. Some 212 studies were implemented. Majority were on tiger shrimp, milkfish, and sea bass. Studies on other species of fishes, crustaceans, molluscs, and seaweeds, as well as larval food organisms, seafarming and economics of hatchery and grow-out culture systems were also undertaken. As of December 1991, 168 studies were completed. Research results were published in 204 scientific journals, proceedings, and other publications. In addition, 27 papers were in press and 63 manuscripts had been submitted. That research output is gaining recognition in the international scientific community can be gleaned from the number of papers published in refereed journals covered by Current Contents (CC). Of the 142 papers published in scientific journals in 1988-1991, 115 (81%) appeared in CCcovered journals. This has increased from 58.8% (124 of 211) in 1976-1987. The active participation of the research staff in scientific meetings is equally evident from the number of publications in proceedings of scientific meetings from 1988-1991 (63)

Testis-Sparing Surgery for Benign Pathologies in Children: A Report of Two Cases

Abstract Aim: The aim of this report is to describe two cases of testis-sparing surgery and to discuss the feasibility, safety and outcome of this treatment modality. Patients and Methods: We here present the cases of two boys, a 12-year-old and a 7-year-old, exhibiting a Large-Cell Calcifying Sertoli Cell Tumor (LCCSCT) and a Leydig Cell Tumor (LCT) respectively. All operations were performed through an inguinal approach by cold ischemia and with organ-sparing surgery. Results: Neither of the patients exhibited intraoperative or postoperative complications. After a mean follow-up of 25 months (range 16–34) the patients were free of disease. Conclusion: Testis-sparing surgery by cold ischemia and frozen-section examination is advisable for pediatric patients with benign testicular masses

Marine fish hatchery: developments and future trends

The basic procedures for producing marine fish fry in hatcheries developed for milkfish fry production nearly 3 decades ago are the basis of fry production systems for all other marine fish species that are now reared in hatcheries in the Philippines and other Southeast Asian countries. These include large-scale microalgae production in outdoor tanks, feeding of appropriate sized rotifer grown on microalgae such as Nannochlorum during the first feeding phase, and shifting to larger prey such as Artemia towards the latter stages of production. In recent years, the increasing demand for high-value species such as groupers, sea bass, red snapper, and pompano in both local and export markets has encouraged a number of hatcheries to produce fry to supply the requirements of fish cage farmers. Techniques are modified using information from research institutions and multi-national firms active in developing products and equipment to improve commercial production of these species. Larval feeds of appropriate sizes, forms and presentation for various larval stages incorporating essential nutrients, micronutrients, and feed stimulants are now available in the market. Diseases in marine fish hatcheries have become common occurrences such that various chemotherapeutants, vaccines, and immunostimulants are now available and increasingly being applied in fish hatcheries. Technological developments in hatchery systems, such as the use of recirculating systems, water pretreatment protocols (ozonation, mircrofiltration, UV light treatment) are also increasingly being adopted by commercial establishments. A critical link between fry production and production of marketable fish is fingerling/ juvenile production in nurseries. Fry are commonly grown in brackishwater fishponds to appropriate size for stocking in fish cages. Methods to improve growth through proper feeding and nutrition, eliminate or reduce disease occurrence and parasite infestation, reduce cannibalism in cannibalistic species such as sea bass, grouper and snappers are active areas of research. Nursery production is integrated with fry production in large commercial facilities but is also done by small-scale fish farmers who have access to fry either from the wild or hatcheries. Commercial hatcheries adopt fingerling production from well-studied species in developed countries. Smallscale farmers however still rely on zooplanktons collected from the wild such as copepods, Moina, mysids, and trash fish as feed. Production is dependent on availability of feed sources and susceptibility to pathogens and parasites that come with the feed. It can also be erratic since smallscale farms are vulnerable to changes in climate and weather conditions. Further technological advancement in marine fish hatcheries will increasingly be led by commercial establishments and industries developing equipment like photobioreactor for microalgae to produce algal paste, or methods to develop intensive systems for rotifer culture. Research institutions will however need to support the needs of the small-scale farmers and hatchery operators who may not be able to apply costly products from these companies by developing innovative simple techniques that can improve culture systems such as producing fry and fingerlings in mesocosm pond system, appropriate use of probiotics as water stabilizer, and production of zooplankton in ponds

Optomechanical deformation and strain in elastic dielectrics

Light forces induced by scattering and absorption in elastic dielectrics lead to local density modulations and deformations. These perturbations in turn modify light propagation in the medium and generate an intricate nonlinear response. We generalise an analytic approach where light propagation in one-dimensional media of inhomogeneous density is modelled as a result of multiple scattering between polarizable slices. Using the Maxwell stress tensor formalism we compute the local optical forces and iteratively approach self-consistent density distributions where the elastic back-action balances gradient- and scattering forces. For an optically trapped dielectric we derive the nonlinear dependence of trap position, stiffness and total deformation on the object's size and field configuration. Generally trapping is enhanced by deformation, which exhibits a periodic change between stretching and compression. This strongly deviates from qualitative expectations based on the change of photon momentum of light crossing the surface of a dielectric. We conclude that optical forces have to be treated as volumetric forces and that a description using the change of photon momentum at the surface of a medium is inappropriate

A guide to the establishment and maintenance of milkfish broodstock

The manual describes methods used at the SEAFDEC Aquaculture Department in order to establish milkfish broodstock. It is presented under the following major section headings: Establishing broodstock farms; Farms for rearing bangus juveniles; Maturation cages for rearing broodstock to maturity; Gathering data; Spawning and egg collection; and Larval rearing.This study as well as the publication of this guide was partly supported by the International Development Research Centre of Canada under Project No. 3-P78-0033 (Phase II) and No. 3-P81-0171 (Phase III)

Wave Packet Echoes in the Motion of Trapped Atoms

We experimentally demonstrate and systematically study the stimulated revival (echo) of motional wave packet oscillations. For this purpose, we prepare wave packets in an optical lattice by non-adiabatically shifting the potential and stimulate their reoccurence by a second shift after a variable time delay. This technique, analogous to spin echoes, enables one even in the presence of strong dephasing to determine the coherence time of the wave packets. We find that for strongly bound atoms it is comparable to the cooling time and much longer than the inverse of the photon scattering rate

Applications of aerospace technology to petroleum extraction and reservoir engineering

Through contacts with the petroleum industry, the petroleum service industry, universities and government agencies, important petroleum extraction problems were identified. For each problem, areas of aerospace technology that might aid in its solution were also identified, where possible. Some of the problems were selected for further consideration. Work on these problems led to the formulation of specific concepts as candidate for development. Each concept is addressed to the solution of specific extraction problems and makes use of specific areas of aerospace technology

Characterization of elastic scattering near a Feshbach resonance in rubidium 87

The s-wave scattering length for elastic collisions between 87Rb atoms in the state |f,m_f>=|1,1> is measured in the vicinity of a Feshbach resonance near 1007 G. Experimentally, the scattering length is determined from the mean-field driven expansion of a Bose-Einstein condensate in a homogeneous magnetic field. The scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. The position and the width of the resonance are determined to be 1007.40 G and 0.20 G, respectively.Comment: 4 pages, 2 figures minor revisions: added Ref.6, included error bar