Milkfish nursery pond and pen culture in the Indo-Pacific region

In culturing milkfish (Chanos chanos ) to marketable size, the fry (total length = 12-15 mm) are usually reared first in nursery ponds or pens (hapa nets) until they become fingerlings (total length = 2 cm or more). The fingerlings are then transferred to the grow-out ponds or pens where they are reared to marketable size. In some countries like the Philippines, fingerling production has become an industry by itself. This paper reviews the state of the art and constraints to and suggests future research directions for milkfish fingerling production in nursery ponds and pens

Environment-friendly schemes in intensive shrimp farming.

International environmental pressure groups call for shrimp importing countries to impose a trade embargo against farmed shrimps produced in a manner considered deleterious to the environment. In fact, Europe had banned in 2000 the importation of shrimps from some Asian countries. The subject of such protest actions included: (1) discharge of substances potentially harmful to marine organisms (chemicals used during pond preparation and therapeutants used during culture period); (2) discharge of excessive organic load during regular water change and harvests; and (3) chemical residues in shrimps harvested and marketed. In the Philippines, a mandate from the national government was given to SEAFDEC in 1996 to rehabilitate the shrimp industry, which almost reached the brink of virtual collapse due to diseases brought about by some environmentally destructive practices. Mangrove-friendly aquaculture or what is sometimes referred to as the environment-friendly aquaculture was launched by AQD as a five-year program starting in 1998. The focus was later changed to shrimp culture and made part of the ASEAN-SEAFDEC Fisheries Consultative Group (FCG) collaborative project with AQD as Lead Department for technology development and verification, and Thailand as Lead Country for promoting the technology within the Southeast Asian region

A simple, analytical, axisymmetric microburst model for downdraft estimation

A simple analytical microburst model was developed for use in estimating vertical winds from horizontal wind measurements. It is an axisymmetric, steady state model that uses shaping functions to satisfy the mass continuity equation and simulate boundary layer effects. The model is defined through four model variables: the radius and altitude of the maximum horizontal wind, a shaping function variable, and a scale factor. The model closely agrees with a high fidelity analytical model and measured data, particularily in the radial direction and at lower altitudes. At higher altitudes, the model tends to overestimate the wind magnitude relative to the measured data

An open dataset for research on audio field recording archives: freefield1010

We introduce a free and open dataset of 7690 audio clips sampled from the field-recording tag in the Freesound audio archive. The dataset is designed for use in research related to data mining in audio archives of field recordings / soundscapes. Audio is standardised, and audio and metadata are Creative Commons licensed. We describe the data preparation process, characterise the dataset descriptively, and illustrate its use through an auto-tagging experiment

Energetics of rocked inhomogeneous ratchets

We study the efficiency of frictional thermal ratchets driven by finite frequency driving force and in contact with a heat bath. The efficiency exhibits varied behavior with driving frequency. Both nonmonotonic and monotonic behavior have been observed. In particular the magnitude of efficiency in finite frequency regime may be more than the efficiency in the adiabatic regime. This is our central result for rocked ratchets. We also show that for the simple potential we have chosen, the presence of only spatial asymmetry (homogeneous system) or only frictional ratchet (symmetric potential profile), the adiabatic efficiency is always more than in the nonadiabatic case.Comment: 5 figure

Addendum to `Gravitational Geons in 1+1 Dimensions'

In a recent paper [arXiv:0807.0611] I found gravitational geons in two classes of 1+1 dimensional theories of gravity. In this paper I examine these theories, with the possibility of a cosmological constant, and find strong field gravitational geons. In the spacetimes in [arXiv:0807.0611] a test particle that is reflected from the origin suffers a discontinuity in $d^2t/d\tau^2$. The geons found in this paper do not suffer from this problem.Comment: To appear in Classical and Quantum Gravit

A Lack of Resolved Near-Infrared Polarization Across the Face of M51

The galaxy M51 was observed using the Mimir instrument on the Perkins telescope to constrain the resolved H-band (1.6 $\mu$m) polarization across the galaxy. These observations place an upper limit of $P_H<0.05$ on the $H$-band polarization across the face of M51, at 0.6 arcsecond pixel sampling. Even with smoothing to coarser angular resolutions, to reduce polarization uncertainty, the $H$-band polarization remains undetected. The polarization upper limit at $H$-band, when combined with previous resolved optical polarimetry, rules out a Serkowski-like polarization dependence on wavelength. Other polarization mechanisms cannot account for the observed polarization ratio ($P_H/P{VRI} \lesssim 0.05$) across the face of M51.Comment: 4 pages, 2 figures, Accepted for publication in ApJ