bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Transfer Analysis of the Curing Process on an Organic Paint Strip Line
Authors: Lavery Nick P. , Brown Steve G. R.
Published: August 2008

A strip of galvanised steel passes at high speed down a large-scale paint line. The strip is coated with various organic or polymer based paints that are cured as the strip is passed through a series of chambers in a convection oven. Each oven chamber is lined above and below by nozzles which blow heated air at high velocity over the strip, serving the dual purpose of curing the paint and maintaining the strip in flotation. The purpose of this work has been to generate a greater understanding of the transient heat transfer mechanisms taking place in the micro layers of the strip by developing a 1-D finite element computer model. This model allows sensitivity analyses to be performed in real time on process parameters with the ultimate goal of optimising the curing rate of the paint for a more economical running of the process. Heat transfer coefficients for the convective heating are derived from film theory, and a comparative empirical model has also been derived for comparison. Further comparison has also been obtained from a full-scale three-dimensional Computational Fluid Dynamic (CFD) model of the ovens using FLUENT. The CFD modelling has allowed existing heat transfer coefficients to be refined taking into account complicating factors such as turbulence of the hotair flow impinging upon the strip and the rapid movement of the strip itself. Results have highlighted the sensitivity of the finite element and empirical models to the heat transfer coefficients being used. Using the model, a matrix of over temperatures for required peak metal temperature (PMT) of the strip was obtained. These temperatures were significantly lower than currently used values allowing long-term cost savings for the running process to be calculated.
Three-Dimensional Numerical Simulation and Performance Study of an Industrial Static Mixer Using Pseudo-Plastic Fluids
Authors: Rahmani Ramin K. , Keith Theo G. , Ayasoufi Anahita
Published: August 2008

Mixing is an essential component of nearly all industrial chemical processes, ranging from simple blending to complex multi-phase reaction systems for which the reaction rate, the yield and the selectivity are highly dependent upon the mixing performance. Consequences of improper mixing include nonreproducible processing conditions and lowered product quality, resulting in the need for more elaborate downstream purification processes and increased waste disposal costs. A wide range of working fluids in industrial mixers are non-Newtonian. The non-Newtonian fluid studied here is a member of the pseudo-plastic fluids group, characterized by a progressively decreasing slope or shear stress versus shear rate. These fluids are termed shear thinning; the viscosity decreases with increasing velocity gradient. In this paper, a previous study by the authors on an industrial helical static mixer is extended to illustrate how static mixing processes of single-phase pseudo-plastic liquids can be simulated numerically. A further aim is to provide an improved understanding of the flow pattern of pseudo-plastic single-phase liquids through the mixer. A three-dimensional finite volume simulation is used to study the performance of the mixer. A commercial software, FLUENT, is used in a part of the numerical simulation. The flow velocities, pressure drops, etc. are calculated for various flow rates, using the Carreau and the power law models for non-Newtonian fluids. The numerical predictions by these two models are compared to existing experimental data. Also, a comparison of the mixer performance for both Newtonian and pseudo-plastic fluids is presented.
A New Formulation for Solids Suitable for a Unified Solution Method for Fluid-Structure Interaction Problems
Authors: Giannopapa C. G. , Papadakis G.
Published: August 2008

In fluid-structure interaction problems, the fluid and solid components are solved separately and information is exchanged along the interface. This work shows the first stage of development and validation of a novel unified solution method suitable for computing fluid-structure interaction problems. In the new method, a single set of equations is used to describe both fluid and solid, while the interface between them is contained within the solution domain itself. This can be achieved by reformulating the solid equations to solve for the same primitive variables used in fluids i.e. velocity and pressure. The PISO algorithm is used to handle the velocity-pressure coupling. Although this is a standard approach for fluids, validation is needed for solids. Two cases are examined: wave propagation in a one-dimensional rod and oscillation of a 2D cantilevered beam. Appropriate set of boundary conditions is chosen for the free surface. The new formulation for solids is stable and robust, thus it can be used in the next stage in the development of a robust algorithm for coupled fluid-structure interaction problems.
Impact of Cavity on Sunroof Buffeting: A Two Dimensional CFD Study
Authors: An Chang-Fa , Alaie Seyed Mehdi , Scislowicz Michael S.
Published: August 2008

Driven by fluid dynamics principles, the concept for buffeting reduction, a cavity installed at the leading edge of the sunroof opening, is analyzed. The cavity provides a room to hold the vortex, shed from upstream, and prevents the vortex from escaping and from directly intruding into the cabin. The concept has been verified by means of a two dimensional simulation for a production SUV using the CFD software — FLUENT. The simulation results show that the impact of the cavity is crucial to reduce buffeting. It is shown that the buffeting level may be reduced by 3 dB by adding a cavity to the sunroof configuration. Therefore, the cavity could be considered as a means of buffeting reduction, in addition to the three currently-known concepts: wind deflector, sunroof glass comfort position and cabin venting. Thorough understanding of the buffeting mechanism helps explain why and how the cavity works to reduce buffeting. Investigation of the buffeting-related physics provides a deep insight into the flow nature and, therefore, a useful hint to geometry modification for buffeting reduction. The buffeting level may be further reduced by about 4 dB or more by cutting the corners of the sunroof opening into smooth ramps, guided by ideas coming from careful examining the physics of flow. More work including three dimensional simulation and wind tunnel experiment should follow in order to develop more confidence in the functionality of the cavity to hopefully promote this idea to the level that it can be utilized in a feasible way to address sunroof buffeting.
CFD Analysis of the Mixing Behaviour of a Stable Stratification in a Cylindrical Tank With a Side-Entry Mixer
Authors: van Looy R. , Kenjeres S. , Hanjalic K. , Al Bataineh K. , Hollander E. , Colenbrander G.
Published: August 2008

Blending of liquids with different densities is often performed by the oil industry. Side-entry mixers are frequently used to homogenize the contents of storage tanks. Normally, empirical correlations are used to determine the mixing time of these mixers. The objective of the work, discussed in this paper is to establish the potential of CFD in determining these mixing times. A buoyancy extended standard k-ε model has been used to model the mixing behaviour in a tank containing two miscible liquids of different density, which are stratified before the mixer is switched on. The agreement with the experiments was not good: the model in some cases underestimated the mixing time by an order of magnitude. In another attempt, LES technique was used to model this problem. The agreement with the experiments became better but still the mixing time in the low Froude number range was seriously underestimated. Work is in progress to refine the LES simulations.
Simulation of the Heat Transfer to a Laminar Flow in a PRIMIX Static Mixer
Authors: Mudde R. F. , Van de Kleij R. J. R. , Beugels R.
Published: August 2008

The heat transfer from the wall to the process fluid in a PRIMIX helical static mixer has been investigated using numerical simulations. The flow is in the laminar regime, Re = 7 to 18. The simulations concentrate on heat transfer from a heated wall to the process fluid. Two different mixers are examined. A conventional one in which the elements are not connected to the wall of the tube and a special one, in which the elements are soldered to the tube wall. In the latter case the heat transfer is enhanced by about 23% which is attractive when dealing with fluids with a low thermal conductivity. The results of the numerical simulations are compared to experiments, both with soldered and without soldered elements. The comparison is good, showing the capabilities of numerical simulations for studying and optimizing heat transfer in static mixers.
Investigation of the Water Flow Into a Mesoporous Matrix From Hydrophobized Silica Gel
Authors: Suciu Claudiu V. , Iwatsubo Takuzo , Yaguchi Kazuhiko , Ikenaga Masayoshi
Published: August 2008

In this work a generalized hydrodynamic theory for the water flow into a mesoporous matrix from hydrophobized silica gel is suggested. Although we examine a fluid dynamics problem, i.e., the motion of the water-gas-solid contact line, motivation for such research derives from the investigation of a novel principle of mechanical energy dissipation, called colloidal damper. Similar to hydraulic damper, this absorber has a cylinder-piston structure, but oil is replaced by a colloid consisted of a mesoporous matrix and a lyophobic liquid. Here, the mesoporous matrix is from silica gel modified by linear chains of alkyldimethylchlorosilanes and water is the associated lyophobic liquid. Mainly, the colloidal damper energy loss can be explained by the dynamic contact angle hysteresis in advancing (liquid displaces gas) and receding (gas displaces liquid); such hysteresis occurs due to the geometrical and chemical heterogeneities of the solid surface. Measuring technique of the hysteresis loop is described. From experimental data one calculates the dissipated energy, damper efficiency and the damping coefficient versus the length of the grafted molecule on the silica gel surface. Experimental results are justified by the flow analysis. Generalized hydrodynamic theory means here that the basic structure of Navier-Stokes equations is kept, but in order to include the relation between macroscopic flow and molecular interactions, slip is allowed on the solid wall. Nano-pillar architecture of the silica gel hydrophobic coating is described. During adsorption, water penetrates the pore space by maintaining contact with the top of the coating molecules (region of -CH3 groups); after that, water is forced into and partially or totally fills the space between molecules (region of -CH2 groups); in such circumstances, at the release of the external pressure, desorption occurs. Mechanism of energy dissipation is discussed. Results obtained are useful for the appropriate design of the hydrophobic coating of a mesoporous matrix which is destined to colloidal damper use.
A Renewed CFD Model for Prediction of Gas-Solid Flow in Downer Reactors
Authors: Ropelato Karolline , Meier Henry F. , Cremasco Marco A.
Published: August 2008

This work provides a renewed space-time muitiphase model known as “insviscid model”, according to terminology of the multiphase flows theory, where the gas-solid modeling presents some special characteristics such as: unsteady and 3D flow for two fluid on an Eulerian-Eulerian appoach; dissipation of turbulent kinetic energy only on the gas as real fluid; and with assumption of solid phase behaves like some kind of hypothetical fluid without shear stress from molecular causes. By using Computational Fluid Dynamics Techniques (CFD), it was carried out the development of the model with studies of Verification and Validation in Computational Fluid Dynamics (V&V in CFD), in order to predict the main fluid dynamic features of down flow reactors of petroleum industry. Despite the simplified modeling, the renewed gas-solid model has shown a good representation of the main phenomenological characteristics of the turbulent gas-solid flow. Numerically, the model does not present difficulties for convergence with traditional finite volume methods with collocated grids and body fitted arrangement of the control volumes. The model considers, as initial condition for space-time integration, the flow of the single phase (gas) to guarantee stability and to achieve the steady state condition. Experimental data obtained in the literature, Cheng et al. [1], were used for model validation, and three others cases for verification of the fluid dynamics effects from different gas-solid inlet condition. By comparison between the model predictions with experimental data, it is possible to conclude there is a good agreement. CFD techniques proved to be also a powerful tool to predict the fluid dynamic of inlet changing of the down flow reactors, and it can be used with success in chemical process optimization.
Germline Allele-Specific Expression of
TGFBR1
Confers an Increased Risk of Colorectal Cancer
Authors: Valle Laura , Serena-Acedo Tarsicio , Liyanarachchi Sandya , Hampel Heather , Comeras Ilene , Li Zhongyuan , Zeng Qinghua , Zhang Hong-Tao , Pennison Michael J. , Sadim Maureen , Pasche Boris , Tanner Stephan M. , de la Chapelle Albert
Published: August 2008

Much of the genetic predisposition to colorectal cancer (CRC) in humans is unexplained. Studying a Caucasian-dominated population in the United States, we showed that germline allele-specific expression (ASE) of the gene encoding transforming growth factor–β (TGF-β) type I receptor,
TGFBR1
, is a quantitative trait that occurs in 10 to 20% of CRC patients and 1 to 3% of controls. ASE results in reduced expression of the gene, is dominantly inherited, segregates in families, and occurs in sporadic CRC cases. Although subtle, the reduction in constitutive
TGFBR1
expression alters SMAD-mediated TGF-β signaling. Two major
TGFBR1
haplotypes are predominant among ASE cases, which suggests ancestral mutations, but causative germline changes have not been identified. Conservative estimates suggest that ASE confers a substantially increased risk of CRC (odds ratio, 8.7; 95% confidence interval, 2.6 to 29.1), but these estimates require confirmation and will probably show ethnic differences.
Polymer Pen Lithography
Authors: Huo Fengwei , Zheng Zijian , Zheng Gengfeng , Giam Louise R. , Zhang Hua , Mirkin Chad A.
Published: August 2008

We report a low-cost, high-throughput scanning probe lithography method that uses a soft elastomeric tip array, rather than tips mounted on individual cantilevers, to deliver inks to a surface in a “direct write” manner. Polymer pen lithography merges the feature size control of dip-pen nanolithography with the large-area capability of contact printing. Because ink delivery is time and force dependent, features on the nanometer, micrometer, and macroscopic length scales can be formed with the same tip array. Arrays with as many as about 11 million pyramid-shaped pens can be brought into contact with substrates and readily leveled optically to ensure uniform pattern development.
Conformational Switch of Syntaxin-1 Controls Synaptic Vesicle Fusion
Authors: Gerber Stefan H. , Rah Jong-Cheol , Min Sang-Won , Liu Xinran , de Wit Heidi , Dulubova Irina , Meyer Alexander C. , Rizo Josep , Arancillo Marife , Hammer Robert E. , Verhage Matthijs , Rosenmund Christian , Südhof Thomas C.
Published: August 2008

During synaptic vesicle fusion, the soluble
N
-ethylmaleimide-sensitive factor–attachment protein receptor (SNARE) protein syntaxin-1 exhibits two conformations that both bind to Munc18-1: a “closed” conformation outside the SNARE complex and an “open” conformation in the SNARE complex. Although SNARE complexes containing open syntaxin-1 and Munc18-1 are essential for exocytosis, the function of closed syntaxin-1 is unknown. We generated knockin/knockout mice that expressed only open syntaxin-1B. Syntaxin-1B
Open
mice were viable but succumbed to generalized seizures at 2 to 3 months of age. Binding of Munc18-1 to syntaxin-1 was impaired in syntaxin-1B
Open
synapses, and the size of the readily releasable vesicle pool was decreased; however, the rate of synaptic vesicle fusion was dramatically enhanced. Thus, the closed conformation of syntaxin-1 gates the initiation of the synaptic vesicle fusion reaction, which is then mediated by SNARE-complex/Munc18-1 assemblies.
Diagnosing overtraining in athletes using the two-bout exercise protocol
Authors: Meeusen R , Nederhof E , Buyse L , Roelands B , de Schutter G , Piacentini M F
Published: August 2008

Objective

In this work, whether a two-bout exercise protocol can be used to make an objective, immediately available distinction between non-functional over reaching (NFO) and overtraining syndrome (OTS) was studied.

Design

Underperforming athletes who were diagnosed with the suspicion of NFO or OTS were included in the study. Recovery of the athletes was monitored by a sports physician to retrospectively distinguish NFO from OTS.

Setting

Sports medicine laboratory

Participants

The protocol was started and completed by 10 underperforming athletes. NFO was retrospectively diagnosed in five athletes, and OTS was diagnosed in five athletes.

Interventions

A two-bout maximal exercise protocol was used to measure physical performance and stressinduced hormonal reactions.

Main outcome measurements

Exercise duration, heart rate and blood lactate concentration were measured at the end of both exercise tests. Venous concentrations cortisol, adrenocorticotrophic hormone (ACTH), prolactin and growth hormone were measured both before and after both exercise tests.

Results

Maximal blood lactate concentration was lower in OTS compared with NFO, while resting concentrations of cortisol, ACTH and prolactin concentrations were higher. However, sensitivity of these measures was low. The ACTH and prolactin reactions to the second exercise bout were much higher in NFO athletes compared with OTS and showed the highest sensitivity for making the distinction.

Conclusions

NFO might be distinguished from OTS based on ACTH and prolactin reactions to a two-bout exercise protocol. This protocol could be a useful tool for diagnosing NFO and OTS; however, more data should be collected before this test can be used as the gold standard.
Intraductal papillary mucinous neoplasms of the pancreas: clinical and pathological features and diagnostic approach
Authors: Katabi N , Klimstra D S
Published: August 2008

Pancreatic intraductal papillary mucinous neoplasms (IPMNs) are mucin-producing neoplasms with a frequent papillary architecture that arise within the pancreatic ducts and are increasingly being recognised. Because they exhibit a spectrum of dysplasia ranging from low grade to high grade and may also have associated invasive carcinoma, and because they are clinically detectable, they are now intensively studied. There is marked overlap between IPMNs and pancreatic intraepithelial neoplasia (PanIN), such that the distinction between these two lesions is nearly impossible in certain cases. In addition, IPMNs sometimes can be confused with other primary cystic lesions of the pancreas. As a result, the correct diagnosis of IPMN can be challenging. This review addresses the clinical and pathological features of IPMNs, emphasising their diagnostic criteria, differential diagnosis and biological behaviour. Problematic issues in the pathological evaluation of IPMNs are discussed.
Power and Evolutionary Fitness of Teleosts
Authors: Ware D. M.
Published: August 2008

The use of optimization arguments in evolutionary biology has been criticized because the methodology requires an assumption about what is being maximized by natural selection. As optimality arguments are often a priori and always speculative, the critics point out that there is no theoretical basis for any maximization principles in biology. They contend that only empirical work can establish if there are some properties of species that are generally maximized by natural selection. I accept this standard for evaluation, and argue that the concept of surplus power, which provides a physiological basis for optimal foraging and life history theory, is related to fitness. Evidence in the form of specific morphological and behavioral traits in teleost fishes is presented to demonstrate that natural selection has increased surplus power. Life history theory is concerned with how power is allocated by organisms to various vital functions; therefore, the specific problem of stock and recruitment in fisheries can be treated as a special application of life history theory. Some implications about the dynamics and possible survival value of different reproductive strategies exhibited by teleosts are discussed.Key words: surplus power, evolutionary biology, optimal foraging, life history theory, fitness
Chemical Communication in Fish
Authors: Liley N. R.
Published: August 2008

Chemical signals (pheromones) have been shown to be involved in schooling, territorial marking, species, sex and individual recognition, courtship, the induction of physiological readiness for mating, and in parent–young interactions. Alarm substances released from damaged skin elicit avoidance behavior. Pheromones may also be involved in homestream recognition in some anadromous species. Most pheromones investigated act as "releasers"; a few "priming" effects have been observed. In most of the chemically mediated interactions surveyed it is not clear that communication in a generally accepted sense is involved, or whether fish are simply responding adaptively to those metabolic products which inevitably "leak" into the environment and only fortuitously provide "information" to conspecifics. In a few cases, specializations in chemical secretions or secretory structures indicate that they have evolved for communication. It is proposed that a combination of factors — the availability of a wide array of soluble biochemical products, the diffuse nature of the sites from which such products might be released, and the lack of strong selection for complex chemical messages — has resulted in the relatively simple "unritualized" systems of chemical communication which appear to be characteristic of fish.Key words: chemical signals, pheromones, reproduction, schooling, homing, parental behavior, fright reaction
Neuroendocrine Control of Reproduction in Teleosts
Authors: Peter R. E.
Published: August 2008

Gonadotropin releasing hormone (GnRH) activity has been demonstrated in crude extracts of the hypothalamus of several teleost species. Teleost GnRH is similar to the GnRH in elasmobranchs, reptiles, and birds. Luteinizing hormone–releasing hormone (LH–RH) or its superactive analogues stimulate gonadotropin (GtH) secretion in teleosts and can induce ovulation. The actions of LH–RH or its analogues can be self-potentiated or self-suppressed by previous exposure to low and high doses, respectively, and the fish may also be able to modulate its response by other means. There is no agreement on the distribution in the brain of LH–RH immunoreactive perikarya and nerve fibers in teleosts, but the main sites for perikarya are the nucleus lateral tuberis (NLT), preoptic region and telencephalon. Lesioning the NLT by electrical current or monosodium L-glutamate demonstrates that it has functional involvement in the stimulation of GtH release, presumably via GnRH. The NLT and pineal are involved in regulation of daily cycles of GtH secretion, which have importance in stimulating gonadal activity. A GtH release-inhibitory factor (GRIF) apparently originates in the anteroventral preoptic region. Abolition of GRIF action on the pituitary by destruction of its origin or its neural pathways to the pituitary cause very high serum levels of GtH in sexually mature females and males, and ovulation of the females; regulation of the ovulatory surge of secretion of GtH probably involves abatement of GRIF and stimulation by GnRH. Sex steroids have a negative feedback effect during gonadal recrudescence; the greatest negative feedback influence is during the spawning period. In sexually immature fish estrogens and androgens aromatizable to estrogens have a positive feedback effect to stimulate accumulation of GtH in the pituitary; this positive feedback effect may be part of the mechanism of onset of sexual maturity or gonadal recrudescence in teleosts. Binding sites in the brain for sex steroids have been investigated by autoradiography, and active locations were found in the NLT, preoptic region, area ventralis of the telencephalon, and parts of the posterior hypothalamus, as well as the pituitary. The functional significance of most of these binding sites is not known.Key words: teleosts, gonadotropin, gonadotropin releasing hormone, gonadotropin release-inhibitory hormone, steroid feedback, nucleus lateral tuberis, nucleus preopticus
Cellular Sources of Sex Steroids in Teleost Gonads
Authors: Nagahama Y. , Kagawa H. , Young G.
Published: August 2008

Histochemical and ultrastructural data on the cellular source of gonadal steroids are reviewed, together with some recent observations on in vitro steroidogenesis by the ovarian follicles of the amago salmon, Oncorhynchus rhodurus. The interstitial cells of the testis appear to be homologous with mammalian Leydig cells and are considered to be the major site of androgen synthesis. Studies on lobule boundary cells suggest that in some species they may be involved in phagocytosis and transport of metabolites while in others they may be steroidogenic. The granulosa cells and the special thecal cells are the major sites of steroid synthesis in the teleost ovary. Studies on the amago salmon using isolated thecal and granulosa layers indicate that both follicle layers are necessary for estradiol-17β production in vitro in response to salmon gonadotropin. The role of the thecal layer during the major part of vitellogenesis is postulated to be the production of estrogen precursors which are converted to estradiol-17β in the granulosa layer. Histochemical and ultrastructural evidence from a number of species for steroid biosynthesis by postovulatory follicles is supported by our recent radioimmunoassay data from white-spotted char, Salvelinus leucomaenis, and the amago salmon showing that young postovulatory follicles can secrete progesterone; the physiological significance of this observation remains to be explained.Key words: teleosts, gonad, steroidogenesis, in vitro, morphology
Endocrine Control of Spermatogenesis in Teleost Fish
Authors: Billard R. , Fostier A. , Weil C. , Breton B.
Published: August 2008

Very different testicular structures and spermatogenetic patterns have been found in fish of the teleost group. Two types of structures may be identified: (i) a tubular type with no lumen (in cyprinodonts); the cysts migrate from the blind end to the vas efferens during the process of spermatogenesis; (ii) a lobular type having a central lumen receiving the spermatozoa released from cysts which remain stationary along the lobule during spermatogenesis. Different spermatogenetic patterns are distinguished in salmonids and cyprinids. In the latter (carp, Cyprinus carpio, and goldfish, Carassius auratus), some germ cell types (e.g. type B spermatogonia and spermatozoa) are present throughout the year, allowing nearly continuous production of good-quality sperm. Studies of their endocrine patterns suggest that the GTH involved is controlled by external (mainly temperature but also photoperiod) and gonadal factors. The GTH stimulates androgen production and eventually controls spermatogenesis and spermiation. In salmonids, the two major events of the testicular cycle, spermatogenesis and spermiation, are temporally separated by a stage of spermatozoal "maturation" during which the spermatozoa undergo physiological changes. Sperm quality declines during the period of spermiation. The initiation of a new spermatogenetic cycle seems possible only when the spermatozoa have been eliminated from the testis, either by the normal process of spermiation or by intratesticular resorption. This also illustrates the spatial independence of spermatogenesis and spermiation. The endocrine pattern of spermatogenesis in salmonids is similar to that in carp but seems different as regards spermiation. This spermiation process includes two steps, initiation and amplification, which require different GTH levels and steroid balance. Among the steroids, 11-ketotestosterone is the major androgen found in the plasma, but its superiority over other androgens in regard to spermiation remains to be demonstrated. Environmental factors (photoperiodic changes and temperature) may act directly on the central nervous system to control gonadotropin secretion. Temperature may also directly influence the gonad, somatic or germ cells, and steroid metabolism which acts either locally on the gonad or more centrally. The regulation of spermatogenesis in fish appears to be more subtle than previously believed. Major unknowns are whether there is a second GTH and, if so, its site of action; which steroids are directly involved in the control of spermatogenesis in the lobules, and which are the target cells; and which factors regulate testicular size and which pituitary GTH secretion. Finally, the poor yield of spermiation is intriguing and requires further study, considering its practical implication in fish-farming.Key words: spermatogenesis, teleosts, salmonids, cyprinids
Chemical Data on Pituitary Gonadotropins and Their Implication to Evolution
Authors: Burzawa-Gerard E.
Published: August 2008

Chemical data on gonadotropins from several vertebrate species are summarized and discussed from an evolutionary point of view. A high degree of homology has been observed between mammalian gonadotropins (LH and FSH) and thyrotropin (TSH). In non-mammalian species the existence of LH and FSH-like hormones has been demonstrated except for squamate and fish species. Especially in fish the number of GTHs is still controversial. One pituitary glycoprotein assumes various gonadotropic functions of the pituitary, and a second pituitary hormone (carbohydrate-poor) acts on fish ovarian growth. GTHs from bird, reptile, amphibian, and fish pituitaries have been purified and chemically characterized (amino acid composition, carbohydrate content). The existence of a quaternary structure has been demonstrated for several tetrapod LHs and fish GTHs. The amino acid composition of α and β subunits purified from turkey (Meleagris gallopavo), and turtle (Chelydra serpentira, Chelonia mydas) LHs and from common carp (Cyprinus carpio) and sturgeon (Acipenser stellatus) GTHs showed homology with the mammalian α and β subunits. The partial sequences of carp GTH subunits have shown that the carp GTH β was more closely related to mammalian LH β than to FSH β. Hybrid molecules could be obtained by association of heterologous subunits. The kinetics of subunit association has been studied in vitro. As compared to ovine LH, subunit association of carp GTH was more rapid and thermodependent. The subunit β seemed to determine the thermodependence. The various GTH subunits in living vertebrate probably derive from a common ancestral molecule.Key words: vertebrate gonadotropins, chemical characterizations, GTHs subunits, amino acid sequences, hybrid molecules, evolution.
Role of Prostaglandins in Fish Reproduction
Authors: Stacey N. E. , Goetz F. W.
Published: August 2008

Prostaglandins (PGs) have been identified in gonads, semen, ovarian fluid, blood, and in vitro ovarian incubates from a variety of teleosts. In teleosts, PGs appear to be involved in ovulation (follicular rupture) and female sexual behavior, and possibly in gonadotropin (GtH) secretion. An increase in prostaglandin F (PGF) levels associated with GtH-induced ovulation occurs in vivo in the pond loach (Misgurnus anguillicaudatus) and goldfish (Carassius auratus). Indomethacin (PG synthesis inhibitor) blocks ovulation in these species and, in goldfish, PG injection reverses this blockade. PGF2α stimulates in vitro ovulation in rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), and yellow perch (Perca flavescens); however, in perch, PGE2 is the most potent prostaglandin. Addition of melatonin to incubation medium both inhibits ovulation and decreases PGE and PGF synthesis in yellow perch, while addition of epinephrine and theophylline both enhances ovulation and increases PGE and PGF synthesis. Several studies indicate that PG, released from the ovaries or oviduct in response to the presence of ovulated oocytes, acts on the brain to stimulate female spawning behavior in the goldfish. Other externally fertilizing teleosts may use similar mechanisms to synchronize female sexual behavior with ovulation.Key words: prostaglandins, fish reproduction, ovulation, sexual behavior
Sex Control in Fish with Particular Reference to Salmonids
Authors: Donaldson Edward M. , Hunter George A.
Published: August 2008

Techniques for sex control in trout, char, and salmon are reviewed in the context of their application to salmonid culture. Procedures for the production of all female, male, or sterile salmonids using estrogen or androgen treatment, respectively, are described and compared for Salmo, Salvelinus, and Oncorhynchus species. The production of homozygous monosex salmonids by radiation gynogenesis and techniques for the production of potentially sterile triploid and polyploid salmonids arc discussed. Finally, alternative sterilization techniques which do not depend on steroid administration or zygote manipulation are reviewed including irradiation, and autoimmune and surgical procedures. Direct and indirect hormonal techniques for production of all female salmonid groups are now sufficiently developed to permit pilot application as is the direct androgen sterilization technique. The procedure of radiation gynogenesis is available for the rapid experimental production of inbred lines. On the other hand, further work is required to determine the effectiveness of induced triploidy and polyploidy as sterilization procedures.Key words: sex reversal, estrogen, androgen, sterilization, gynogenesis, androgenesis, polyploidy, Salmo, Oncorhynchus, Salvelinus
Applications of Endocrinology to Fish Culture
Authors: Lam T. J.
Published: August 2008

Endocrinology has, or may have, important applications in four major activities of fish culture viz induced breeding, larval rearing, "grow-out," and broodstock development and management. The current state of knowledge regarding these applications is reviewed and discussed. For induced breeding, this includes discussion of the use of fish pituitary extract ± HCG (human chorionic gonadotropin); HCG alone; partially purified teleost gonadotropins; LH–RH (luteinizing hormone–releasing hormone) and its superactive analogues; clomiphene citrate and other antiestrogens; corticosteroids ± pituitary extract; progestogens ± pituitary extract; and prostaglandins. In larval rearing, use of thyroxine (Eltroxin), which accelerates larval and fry development and growth in a few teleosts, is suggested. In "grow-out" (growth of fry to marketable size), the use of hormones to enhance fish growth and the use of steroids in sex control to facilitate monosex culture are briefly reviewed. Finally, in broodstock development and management, the use of hormones to induce spermatogenesis or vitellogenesis in broodfish is considered.Key words: endocrinology, hormones, fish culture, induced breeding, larval rearing, fish growth enhancement, sex control, induced gonadal development
Fish Culture in Southeast Asia
Authors: Lam T. J.
Published: August 2008

This paper is a brief review of fish culture in the Association of Southeast Asian Nations (ASEAN) countries (Indonesia, Malaysia, Philippines, Singapore, and Thailand) based on latest available data.Key words: fish culture, southeast Asia, ASEAN
Polycultural System of Freshwater Fish in China
Authors: Hao-Ren Lin
Published: August 2008

China is a country in which fish culture is closely integrated with conventional agriculture. Its success depends on the firm base of traditional practices as well as the introduction of many innovations. Among them, polyculture is probably the most important reason for fish culture's success. The major advantage of polyculture is to utilize fully the space and food available in the pond and to optimize interactions between compatible species with different feeding habits and ecology. The different types of polycultural pond stocking are adapted in accordance with (1) the climate, (2) quality of water supply and fertility of pond, (3) availability of fish fry and fingerlings, (4) availability of food and fertilizer, and (5) market requirements. The artificial propagation of cultured fishes and large-scale production of fry and fingerlings are the major development of Chinese fish culture in recent years. The application of LH–RH analogue as a new highly effective ovulating agent for fish reproduction has been carried furthest in China.Key words: China, fish polyculture, Chinese carp, induced spawning, LH–RH analogue, fry, fingerling, fish production
Influence of Temperature Selection upon the Chlorine Avoidance of Cold-Water and Warmwater Fishes
Authors: Cherry Donald S. , Larrick Stephan R. , Giattina James D. , Cairns Jr. John , Hassel John Van
Published: August 2008

The avoidance response of selected cold-water (stenothermal) and warmwater (eurythermal) fish species to total residual chlorine (TRC) was found to be species specific, influenced by temperature, and dependent upon the constituents within the TRC. The first significant avoidance of TRC (primarily free chlorine) at 12 and 18 °C occurred at concentrations ranging from 0.05 to 0.10 mg/L for salmonids — rainbow trout (Salmo gairdneri), and coho salmon (Oncorhynchus kisutch) — and 0.10 to 0.40 mg/L at 12 and 24 °C for the eurythermal species — largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), and mosquitofish (Gambusia affinis). A greater concentration of TRC was necessary to initiate avoidance at the highest acclimation temperature for most fish species tested although the amount of hypochlorous acid (HOCl) within the TRC was approximately the same regardless of the acclimation temperature at each avoidance concentration. For exposures comprised mainly of monochloramine (MONOCl), initial avoidance concentrations were generally equal to or greater than concentrations avoided in the TRC trials. After attraction into heated water, bluegill and largemouth bass avoided some TRC or MONOCl concentrations which were either equal to or twofold greater than the concentrations determined in tests without temperature attraction; for mosquitofish, the differences were as much as three to four times greater. Temperature attraction into chlorinated water was less influential for salmonids in elevating the avoidance response of chlorine with only a twofold increase in the avoidance concentration of TRC and none for MONOCl.Key words: chlorine avoidance, chlorine toxicity, temperature selection, stenothermal fish, eurythermal fish
Dosage automatique de l'urée dans l'eau de mer: une méthode très sensible à la diacétylmonoxime
Authors: Aminot A. , Kerouel R.
Published: August 2008

The determination of urea in sea water was performed by an automated method based on the reaction of urea with diacetyl-monoxime. The sensitivity, which has been greatly enhanced compared to previous methods, by using reagents containing thiosemicarbazide and iron III, is 0.044 absorbance units/μg-at urea-N/L with the 50 mm flow cell. The precision is ±0.01 μg-at urea-N/L and the limit of detection (2 SD) is 0.02 μg-at urea-N/L. The absorbance–concentration relationship is linear up to 15 μg-at urea-N/L. The analytical blanks have been strictly determined and the interferences studied. Citrulline is the main compound that interferes. However, in attempting to remove this compound from the samples by a chelating resin, we demonstrated its absence from the analyzed coastal waters. The color development with urea does not depend on the salt concentration. The problems of contamination and storage are discussed: great care must be taken in handling the samples; quickly freezing the samples is proved very suitable for storage during a long time. Some examples of application of the method to oceanic, coastal and estuarine waters show concentrations ranging from 0.00 to 3.0 μg-at urea-N/L.
Effects of Temperature on Utilization of Yolk by Chinook Salmon (Oncorhynchus tshawytscha) Eggs and Alevins
Authors: Heming T. A.
Published: August 2008

Growth, development and survival of chinook salmon (Oncorhynchus tshawytscha) during the yolk absorption period (fertilization to complete yolk absorption) were examined at 6, 8, 10, and 12 °C. Higher rearing temperatures reduced both the duration of the yolk absorption period and the overall amount of energy available for tissue growth during that period. Salmon encountered a metabolic energy deficit before yolk reserves were exhausted; tissues were resorbed during absorption of the last 10 mg (dry weight) of yolk. Salmon held above 10 °C experienced reduced survival, hatched and emerged precociously, and were smaller at hatching, at emergence, at maximum tissue weight and at complete yolk absorption than fish at lower temperatures.Key words: temperature, yolk utilization, Oncorhynchus tshawytscha, fish eggs, alevins
Environmental Factors Affecting Predation Rates of Mysis relicta
Authors: Cooper Scott D. , Goldman Charles R.
Published: August 2008

Mysis relicta was fed Epischura nevadensis late instars or Diaptomus tyrrelli males in a series of feeding experiments. Mysis clearance rates were not affected by the time of day mysids were collected, the time of day experiments were conducted, or conditioning of experimental water by predators and prey. Mysis fed as efficiently in the dark as in bright light, and exhibited increasing clearance rates with increasing container size. When Diaptomus males were used as prey Mysis clearance rates were significantly higher at 5 °C than 10 and 15 °C; temperature did not affect clearance rates with Epischura as prey. Mean clearance rates tended to decline with increasing prey density, but the only significant differences were recorded when Epischura was used as prey. Prior acclimation to experimental light and temperature conditions had no effect on the results. When presented with an abundant food supply, freshly collected Mysis fed at initially low rates. Subsequent feeding rate peaks were followed by feeding rate declines to low levels over a 24-h period. Individual Mysis consumption rates remained relatively constant from day to day.Key words: Mysis relicta, predation, copepods, clearance rates, opossum shrimp
Variable Kinematics of Sacramento Perch (Archoplites interruptus) Capturing Evasive and Nonevasive Prey
Authors: Vinyard Gary L.
Published: August 2008

Kinematic analysis of the prey attack behavior of Sacramento perch (Archoplites interruptus) for familiar nonevasive prey (Daphnia magna), and for novel evasive prey (Diaphanosoma brachyurum) was undertaken using video taping. The fish use two distinct attack modes. The attack on nonevasive prey is characterized by leisurely approach and relatively conservative attack motions. Attacks on evasive prey are very vigorous and energetically more demanding. Vigorous attacks on the evasive prey which were successful 55% of the time required approximately four times as much energy per attack as did the always successful attacks on the nonevasive prey. Differences between the evasive and nonevasive prey were rapidly learned as shown by the development of the vigorous attack in naive fish, which generally occurred in 10–20 encounters.Key words: predation, behavior, learning, evasion, kinematics, Archoplites interruptus
Optimal Utilization of Fisheries with Increasing Costs of Effort
Authors: Anderson Lee G.
Published: August 2008

The effect that using increasing cost of effort functions will have on economic efficiency conditions as compared to constant cost functions is demonstrated. Except in special circumstances it is only when the increasing cost function is due to an average cost supply curve do these conditions differ. In this case proper regulation must control for the physical production externality as well as a cost externality concerning the production of effort.Key words: fisheries economics, fisheries management, effort costs
A Simplified Preparation for Adenosine Triphosphatase Determination in Gill Tissue
Authors: Zaugg W. S.
Published: August 2008

A simplified preparation from gill tissue that yields adenosine triphosphatase activities comparable to some microsomal fractions is described. The procedure uses two short (6 and 7 min), low speed (2000 Relative Centrifugal Force) centrifugations at room temperature in contrast to long, high speed, refrigerated centrifugations usually associated with microsomal preparations.Key words: gill ATPase, ATPase, fish
Immunization of Brook Trout (Salvelinus fontinalis) against Aeromonas salmonicida: Immunogenicity of Virulent and Avirulent Isolates and Protective Ability of Different Antigens
Authors: Cipriano Rocco C.
Published: August 2008

Brook trout (Salvelinus fontinalis) passively immunized with antisera from rainbow trout (Salmo gairdneri) prepared against virulent or avirulent cultures of Aeromonas salmonicida were equally protected from challenges with concentrated suspensions (109 cells/mL) of A. salmonicida. Brook trout immunized with washed or unwashed formalin-killed virulent cells of A. salmonicida had mean humoral agglutinating antibody titers of 14 (washed cells) and 205 (unwashed cells) after 21 d. However, fish so immunized were not protected when exposed to a virulent challenge. Trout inoculated with crude extracellular material extracted from culture supernatants had a mean agglutinin titer of 122, and fish so immunized were resistant to challenge. Keywords: Aeromonas salmonicida, Salvelinus fontinalis, Salmo gairdneri, immunization, antigens, extracellular material, protection, challenge, fishes
Cluster Sampling Estimation of the Variance of Abundance Estimates Derived from Quantitative Echo Sounder Surveys
Authors: Williamson Neal J.
Published: August 2008

Serial correlation in data collected from fisheries acoustic surveys may have an effect on the precision and accuracy of fish abundance estimates. A simple random sample approach to the data analysis yields unreliable confidence intervals for mean population density when the degree of serial correlation in the data is high. The results of a simulation analysis indicate that more reliable confidence intervals can be obtained using cluster sampling estimation techniques.Key words: acoustic surveys, fish abundance estimates, cluster sampling, serial correlation
DO SUBLEADING CORRECTIONS TO BEKENSTEIN–HAWKING ENTROPY HOLD THE KEY TO QUANTUM GRAVITY?
Authors: SHANKARANARAYANAN S.
Published: August 2008

Black-holes are considered to be theoretical laboratories for testing models of quantum gravity. It is usually believed that any candidate for quantum gravity must explain the microscopic origin of the Bekenstein–Hawking (S BH ) entropy. In this letter, we argue (i) the requirement for a candidate approach to go beyond S BH and provide generic subleading corrections, and (ii) the importance to disentangle and identify the degrees of freedom leading to S BH and its subleading corrections. Using the approach of entanglement of modes across the horizon, we show that the microscopic degrees of freedom that lead to S BH and subleading corrections are different. We further show, using microcanonical and canonical ensemble approaches, that the quantum entanglement predicts generic power-law corrections to S BH and that the corrections can be identified with the kinematical properties of the event-horizon.