990 resultados para 126-792
Resumo:
The broad scale features in the horizontal, vertical, and seasonal distribution of phytoplankton chlorophyll a on the northeast U.S. continental shelf are described based on 57,088 measurements made during 78 oceanographic surveys from 1977 through 1988. Highest mean water column chlorophyll concentration (Chlw,) is usually observed in nearshore areas adjacent to the mouths of the estuaries in the Middle Atlantic Bight (MAB), over the shallow water on Georges Bank, and a small area sampled along the southeast edge of Nantucket Shoals. Lowest Chlw «0.125 ug l-1) is usually restricted to the most seaward stations sampled along the shelf-break and the central deep waters in the Gulf of Maine. There is at least a twofold seasonal variation in phytoplankton biomass in all areas, with highest phytoplankton concentrations (m3) and highest integrated standing stocks (m2) occurring during the winter-spring (WS) bloom, and the lowest during summer, when vertical density stratification is maximal. In most regions, a secondary phytoplankton biomass pulse is evident during convective destratification in fall, usually in October. Fall bloom in some areas of Georges Bank approaches the magnitude of the WS-bloom, but Georges Bank and Middle Atlantic Bight fall blooms are clearly subordinate to WS-blooms. Measurements of chlorophyll in two size-fractions of the phytoplankton, netplankton (>20 um) and nanoplankton «20 um), revealed that the smaller nanoplankton are responsible for most of the phytoplankton biomass on the northeast U.S. shelf. Netplankton tend to be more abundant in nearshore areas of the MAB and shallow water on Georges Bank, where chlorophyll a is usually high; nanoplankton dominate deeper water at the shelf-break and deep water in the Gulf of Maine, where Chlw is usually low. As a general rule, the percent of phytoplankton in the netplankton size-fraction increases with increasing depth below surface and decreases proceeding offshore. There are distinct seasonal and regional patterns in the vertical distribution of chlorophyll a and percent netplankton, as revealed in composite vertical profiles of chlorophyll a constructed for 11 layers of the water column. Subsurface chlorophyll a maxima are ubiquitous during summer in stratified water. Chlorophyll a in the subsurface maximum layer is generally 2-8 times the concentration in the overlying and underlying water and approaches 50 to 75% of the levels observed in surface water during WS-bloom. The distribution of the ratio of the subsurface maximum chlorophyll a to surface chlorophyll a (SSR) during summer parallels the shelfwide pattern for stability, indexed as the difference in density (sigma-t) between 40 m and surface (stability 40. The weakest stability and lowest SSR's are found in shallow tidally-mixed water on Georges Bank; the greatest stability and highest SSR's (8-12:1) are along the mid and outer MAB shelf, over the winter residual water known as the "cold band." On Georges Bank, the distribution of SSR and the stability40 are roughly congruent with the pattern for maximum surface tidal current velocity, with values above 50 cms-1 defining SSR's less than 2:1 and the well-mixed area. Physical factors (bathymetry, vertical mixing by strong tidal currents, and seasonal and regional differences in the intensity and duration of vertical stratification) appear to explain much of the variability in phytoplankton chlorophyll a throughout this ecosystem. (PDF file contains 126 pages.)
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The Alaska Fisheries Science Center (AFSC), National Marine Fisheries Service (NMFS), hosted an international workshop, 'The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems," from 28 to 30 October 1993. This workshop was held in conjunction with the annual International North Pacific Marine Science Organization (PICES) meeting held in Seattle. Nearly 100 representatives from government agencies, universities, and the fishing industry in Canada, Japan, the People's Republic of China, Russia, and the United States took part in the workshop to review and discuss current knowledge on juvenile pollock from the postlarval period to the time they recruit to the fisheries. In addition to its importance to humans as a major commercial species, pollock also serves as a major forage species for many marine fishes, birds, and mammals in the North Pacific region. (PDF file contains 236 pages.)
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Áudio MP3 do texto da Lei nº 11.126, de 27 de junho de 2005, que dispõe sobre o direito do portador de deficiência visual de ingressar e permanecer em ambientes de uso coletivo, acompanhado de cão guia e do Decreto nº 5.904, de 21 de setembro de 2006, que regulamenta a Lei nº 11.126.
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[ES] En este artículo se exponen los resultados obtenidos en una investigación descriptiva sobre la feminización del ámbito lector en la Literatura Infantil y Juvenil (LIJ) vasca. La tesis que desde el principio sostuvo esta investigación se fundamentó en que el progresivo aumento de la presencia de la mujer en el sistema literario vasco tendría que reflejarse también de alguna manera en el ámbito lector. Se utilizó el cuestionario como instrumento metodológico y se eligió una población escolar de 300 niños y niñas de edades comprendidas entre los 11 y 12 años en Vitoria. Se verificó la hipótesis preliminar; no obstante, se detectó una tendencia clara a una mayor presencia femenina en las lecturas de las niñas que en la de los niños. Las lectoras leen un mundo imaginario en un 21.6% más femenino que los lectores.
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Zebrafish (Danio rerio) embryos have been used to quantify the teratogenic potential of environmental samples and harmful substances respectively. The short spawning interval renders this species a good test organism in toxicological research. Due to the transparency of the eggs several lethal and non-lethal endpoints can be detected in parallel after 48 h of embryonic development. Zebrafishembryos have been shown to be sensitive to a number of environmental relevant contaminants, as well as to ex-tracts from polluted sediments
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The spring session of ACFM gave advice for a number of stocks in the North Atlantic, North Sea and Baltic. The present assessment of the situation is given here for stocks of higher importance for the German fishery. These are: Blue Whiting: the stock is still relatively high, this, however, will not last very long, due to too intense fishing. Cod in Kattegat: stock is outside safe biological limits. No immediate recovery in sight. Cod in 22–24 (Baltic): stock is inside save biological limits. F, however, is above the recommendation of the IBSFC. Greenland Halibut: state of the stock not quite clear. The present fishing intensity seems to be sustainable. Herring (Atlanto- scandian, Norwegian spring spawner): stock is within safe biological limits, weak recruitment of the recent years will lead to a reduction of biomass. Herring: for Baltic spring spawner in 22–24 and IIIa still no increasing tendency detectable. North Sea Herring: further increasing tendency, with 900 000 t over B lim, good recruitment. Herring in VIa: stable. Redfish: generally decreasing tendency observed, a reduction of the fishery is recommended. Signs of recovery, however, visible for some units
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398 p. : il., col.
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Capítulo 4 del libro: Guisasola, Jenaro ; Garmendia, Mikel (eds.) "Aprendizaje basado en problemas, proyectos y casos: diseño e implementación de experiencias en la universidad" (ISBN: 978-84-9860-959-2)
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(ES) En el presente artículo trata de poner de relieve los mecanismos utilizados por Aristófanes en Lisístrata para presentar de forma paródica el sacrificio juratorio con el que las mujeres sellan el pacto para obligar a sus maridos a que firmen la paz. Se analiza en este trabajo la utilización del vocabulario específico y la organización básica de este ritual, que Aristófanes conserva intacto, en contraste con la sustitución operada en cuanto a la persona que realiza el sacrificio y a la víctima sacrificial, una jarra de vino de Tasos. Esta elección entronca con el motivo cómico del amor de las mujeres al vino, al que se dedica la segunda parte de este trabajo.
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Twenty four matured samples of Bagrus bayad macropterus from the wild (Shiroro Lake, Nigeria) and under captivity, size ranging from 412.69-3300.00 g total body weight, were analysed for sexual maturity,fecundity and egg size. The average fecundity obtained were 53352.59 and 21028.32 eggs for the wild and cultured fish respectively.Positive relationship was observed between fecundity, body size and gonad weight. Fecundity increased as body size increased. A more positive and linear relationship was observed between fecundity and gonad weight than fecundity and total body weight. Egg diameter,length and weight were determined from the egg samples. The mean size range of eggs for cultured fish was 0.74-1.05 mm of diameter; 1.01-1.20 mm of length and 0.25-0.40 mg of weight. Wild samples had mean size range of 0.68-l.09 mm of diameter, 0.85-1.38 mm of length and egg mean weight range was 0.15- 0.40 mg. Sexual maturity is dependent on size (1 kg and above). The egg diameter, egg length and weight bear no relationship with each other. Gonad development study indicated that gonad development was faster under captivity than in wild
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Limnological studies in Lake Victoria (Kenyan portion) have been sporadic. Water quality and nutrient dynamics studies are being undertaken in fifteen sampling sites that have been divided into four ecological zones namely: Nyanza Gulf, Rusinga Channel, open waters inshore and open waters. The ongoing study will show how the physical and chemical paramenters affect fish distribution and abundance.
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采用透射电镜及附带能谱(TEM-EDS)对K418高温合金涡轮盘和42CrMo合金钢转轴激光焊焊缝的微观组织进行了分析.结果表明:焊缝主要由树枝状非平衡凝固的FeCrNiC(γ)固溶体组成,此外,还有少量细小、弥散的Ni_3Alγ'相、Laves颗粒和少量MC碳化物分布在树枝晶之间区域;根据热动力学原理对形成这一组织特征的原因进行了简要讨论.
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The density distribution of inhomogeneous dense deuterium-tritium plasmas in laser fusion is revealed by the energy loss of fast protons going through the plasma. In our simulation of a plasma density diagnostics, the fast protons used for the diagnostics may be generated in the laser-plasma interaction. Dividing a two-dimensional area into grids and knowing the initial and final energies of the protons, we can obtain a large linear and ill-posed equation set. for the densities of all grids, which is solved with the Tikhonov regularization method. We find that the accuracy of the set plan with four proton sources is better than those of the set plans with less than four proton sources. Also we have done the density reconstruction especially. for four proton sources with and without assuming circularly symmetrical density distribution, and find that the accuracy is better for the reconstruction assuming circular symmetry. The error is about 9% when no noise is added to the final energy for the reconstruction of four proton sources assuming circular symmetry. The accuracies for different random noises to final proton energies with four proton sources are also calculated.
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[EN] Some authors have suggested that body weight dissatisfaction may be high in students majoring in dietetics. Therefore, this study was conducted to examine the extent of body weight and image dissatisfaction in a sample of women in dietetics major. Additionally, predictors of magnitude of body weight dissatisfaction were analyzed. Participants were 62 volunteers with normalweight whose mean age was 21.87±1.89 years old (nonrandom sample). The assessment instruments included anthropometric measurements, a somatomorphic matrix test and an eating disorders inventory (EDI-2). Data were analyzed using SPSS vs. 15.0. A larger proportion of students chose an ideal body weight lower than actual weight (67.7%) and body image with less body fat and more muscle mass than actual values (56.4%). The magnitude of body weight dissatisfaction was associated with muscle mass and body fat dissatisfaction, and with the subscale of EDI-2 “body dissatisfaction”. So, from a public health standpoint, we consider important to continue working in this line of research with the aim of better understanding the extent of body weight dissatisfaction in women dietitians, and how this dissatisfaction could interfere with their professional practice.