Temperature dependence of femtosecond laser induced refractive index change in Nd3+-doped phosphate glass

We report refractive index change in a femtosecond laser irradiated Nd3+-doped phosphate glass. The effects of annealing temperature on the refractive index change of the glass have been investigated. Absorption spectra of the glass sample before and after femtosecond laser irradiation and subsequent annealing were measured. The results indicate that multiphoton absorption can undertake although there are intrinsic absorption for the glass in irradiation wavelength. The results may be useful for fabrication of three-dimensional integrated optics devices and waveguide laser devices in this glass. (c) 2004 Elsevier B.V. All rights reserved.

Graded index 532HR/1064HT filter by glancing angle deposition

Glancing angle deposition is a novel method to prepare graded index coatings. By using this method and physical vapour deposition, ZrO2 is used to engineer graded index filter on BK7 glass substrate. Controlling the deposition rate and the periodic oscillation of oblique angle of deposited material, a 10-period graded index ZrO2 filter with high reflection near 532 nm and high transmittance at wavelength 1064 nm is fabricated. The causes of difference between the theoretical and experimental results are discussed in detail. The material properties and electron gun nonlinearity are possibly the main origins of the difference, which result in the variations in both thickness control and deposition rate of the Elm material.

High refractive index TiO2 film deposited by electron beam evaporation

The well known 'crystal seed' theory is first applied in this work to prepare TiO2 film: a high refractive index rutile TiO2 film is grown by electron beam evaporation on the rutile seed formed by 1100 degrees C annealing. The average n is larger than 2.4, by far the highest in all the authors' TiO2 films. The films are characterised by optical properties, microstructure and surface morphologies. It is found that the refractive index shows positive relation with the crystal structure, grain size, and packing density and roughness of the film. The film has lower density of granularity and nodule defects on the surface than those of the film deposited by magnetron sputtering. The result shows attractive application in complex filter and laser coatings.

A Novel Scheduling Index Rule Proposal for QoE Maximization in Wireless Networks

This paper deals with the resource allocation problem aimed at maximizing users' perception of quality in wireless channels with time-varying capacity. First of all, we model the subjective quality-aware scheduling problem in the framework of Markovian decision processes. Then, given that the obtaining of the optimal solution of this model is unachievable, we propose a simple scheduling index rule with closed-form expression by using a methodology based on Whittle approach. Finally, we analyze the performance of the achieved scheduling proposal in several relevant scenarios, concluding that it outperforms the most popular existing resource allocation strategies.

Prediction of discard mortality for Alaskan crabs after exposure to freezing temperatures, based on a reflex impairment index

Millions of crabs are sorted and discarded in freezing conditions each year in Alaskan fisheries for Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio). However, cold exposures vary widely over the fishing season and among different vessels, and mortalities are difficult to estimate. A shipboard experiment was conducted to determine whether simple behavioral observations can be used to evaluate crab condition after low-temperature exposures. Crabs were systematically subjected to cold in seven different exposure treatments. They were then tested for righting behavior and six different ref lex actions and held to monitor mortality. Crabs lost limbs, showed ref lex impairment, and died in direct proportion to increases in cold exposure. Righting behavior was a poor predictor of mortality, whereas reflex impairment (scored as the sum of reflex actions that were lost) was an excellent predictor. This composite index could be measured quickly and easily in hand, and logistic regression revealed that the relationship between reflex impairment and mortality correctly predicted 80.0% of the mortality and survival for C. bairdi, and 79.4% for C. opilio. These relationships provide substantial improvements over earlier approaches to mortality estimation and were independent of crab size and exposure temperature.

Biodiversity as an index of regime shift in the eastern Bering Sea

Data collected from an annual groundf ish survey of the eastern Bering Sea shelf from 1975 to 2002 were used to estimate biomass and biodiversity indexes for two fish guilds: f latfish and roundfish. Biomass estimates indicated that several species of f latfish (particularly rock sole, arrowtooth flounder, and f lathead sole), several large sculpins (Myoxocephalus spp.), bigmouth (Hemitripterus bolini), and skates (Bathyraja spp.) had increased. Declining species included several f latfish species and many smaller roundfish species of sculpins, eelpouts (Lycodes spp.), and sablefish (Anoplopoma fimbria). Biodiversity indexes were calculated by using biomass estimates for both guilds from 1975 through 2002 within three physical domains on the eastern Bering Sea shelf. Biodiversity trends were found to be generally declining within the roundfish guild and generally increasing within the f latfish guild and varied between inner, middle, and outer shelf domains. The trends in biodiversity indexes from this study correlated strongly with the regime shift reported for the late 1970s and 1980s.

Use of a fishery independant index to predict recruitment and catches of the spiny lobster

This paper presents a review of recruitment and catch predictions based on an index of abundance of juveniles and pre-recruits (fishery independent index) in the Cuban lobster fisheries. This methodology can provide information based on fisheries data that can improve the management of the fishery.

A simple and objective bioeconomic index for choosing species for culture

Details are given of the development of a bioeconomic culture index that may be used to assist in choosing fish for culture. This index takes into account growth performance indexes and mean annual prices of the fish. Examples are given of the culture indices of some of Kuwait's commercially important fish species. The proposed indices given realistic output for these fish and allow comparison and evaluation of different taxa with widely differing biological and economic characteristics.

An Index of Abundance for Coastal Species of Juvenile Sharks from the Northeast Gulf of Mexico

A fishery-independent assessment of juvenile coastal shark populations in U.S. waters of the northeast Gulf of Mexico was conducted using two methods: gillnets and longlines. Surveys were conducted monthly during April–October in two fixed sampling areas from 1996 to 1998. The Atlantic sharpnose shark, Rhizoprionodon terraenovae, and the blacktip shark, Carcharhinus limbatus, were the most common species captured with either longlines or gillnets. An additional 14 shark species were captured, and juvenile indices of abundance were developed for 8 species with gillnets and 6 species of sharks with longlines. Trends in catch-per-unit-effort were found to vary depending on species. Length-frequency information revealed that the majority of sharks captured were juveniles. Given the direct relationship between stock and recruitment for sharks, continued monitoring of juvenile abundance will aid in determining the strength of the parental stock size and for predicting future population strength.