969 resultados para Aikin, Lucy, 1781-1864
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Essa pesquisa é um estudo de caso sobre a interação do aluno com a interface da plataforma Moodle. Para tal, foram utilizadas técnicas consolidadas de avaliação da usabilidade de interfaces digitais. Assim, com respaldo na Semiótica do americano Charles Sanders Peirce, verificou-se e discutiu-se questões subjetivas dos processos comunicativos envolvidos nos problemas interacionais identificados. Uma vez analisado o impacto desses problemas, desenhou-se um quadro geral, denominado experiência do usuário, no qual as interfaces avaliadas são arenas das frustrações e ações que esta proposta de inspeção foi capaz de descrever. A partir desse quadro, foram fundadas as bases para compreensão do modelo mental do usuário para propor soluções. Essas soluções são baseadas, principalmente, em prescrições de usabilidade de Jakob Nielsen, Donald Norman e Steve Krug Nesse cenário, é demonstrado como o design contribui para a elaboração de uma interface que convida à ação e reflexão, de forma a proporcionar um ambiente de interação satisfatório e consonante com as novas tendências educacionais e da cibercultura. Deste modo, também demonstra-se de que forma a Semiótica pode instrumentalizar o profissional de design a resolver situações de projeto. Por meio da documentação de metodologias e resultados, esta pesquisa apoia a boa comunicação entre projetistas, ressalta a importância da subjetividade no estudo interacional, além de propor soluções para os problemas encontrados. Em virtude dos fatos supracitados, essa pesquisa tem como produto final um acervo de informações relevantes para o histórico de projetos em design. Contemplados os requisitos de usabilidade propostos por essa pesquisa, espera-se que, no futuro, tais requisitos sejam validados, para que o impacto produzido pelas mudanças implementadas possam ser avaliados. Assim, poderá ser verificado como essas mudanças impactarão no processo comunicativo da nova proposta interacional e se elas se converteram realmente em satisfação na experiência do usuário. Com isso, pretende-se que o foco da interface passe a ser a associação da satisfação do uso ao processo de aprendizagem.
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Background: The rising temperature of the world’s oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings: Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers’ field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance: Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch’s Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate
Resumo:
绣球科绣球族包含9属:草绣球属、叉叶蓝属、Broussaisia、常山属、绣球属、蛛网萼属、赤壁木属、冠盖藤属和钻地风属。到目前为止,绣球族内的属间关系还不清楚,族内的系统发育关系还有争论。本研究的目的是在前人研究的基础上,进一步发现新的系统学性状,为绣球族乃至绣球科补充新的证据;并综合多学科的研究结果进行分析,探讨绣球族的系统学关系。 本文研究了绣球族的外部形态学、花发育形态学、解剖学、分子系统学和分支系统学。 主要内容包括: 1. 形态学 通过标本室研究和野外观察,对绣球族植物的形态分化进行了分析。发现习性、地上茎的生存期限、花冠卷叠式、花瓣联合与否、花柱的联合程度、雄蕊的数目及排列具有系统学价值;放射花和果实是很好的分类性状,但并非可靠的系统学性状。 2. 花发育形态学 在扫描电子显微镜下,研究了绣球族常山属、绣球属、冠盖藤属、蛛网萼属共4种植物花器官发生和发育的全过程。发现它们的花萼均为螺旋式相继发生,花瓣的发生近乎同时。冠盖藤、马桑绣球及常山具两轮雄蕊,第一轮雄蕊发生于花瓣内轮正对萼片中部的位置,随后第二轮雄蕊发生于正对花瓣中部的位置。在第一轮雄蕊略靠内的位置形成第二轮雄蕊的时候,多数情况下,相邻的对萼雄蕊之间只形成1个对瓣雄蕊,但有时却形成2个对瓣雄蕊,使雄蕊群的数目略多于花被的数目。对萼雄蕊与对瓣雄蕊的分化方式基本一致,但它们在花芽中空间取向不同。 蛛网萼雄蕊数目极多,雄蕊群的发生式样较为独特,并不始于对萼三联体。最早的雄蕊于杯状体近基部发生,之后雄蕊的发生大致沿杯状体壁向上,具离心趋势。在雄蕊发生过程中杯状体继续伸长,为众多雄蕊的发生提供了空间。蛛网萼雌蕊的发生明显早于雄蕊,其它3种植物雌蕊的发生晚于雄蕊。4种植物的雌蕊在发生上较为相似,发育却不同。在常山、马桑绣球和蛛网萼中,花柱从开始到发育成熟始终分离,柱头在每个花柱的顶端形成;而冠盖藤属的花柱裂片从开始就是联合的,最终形成单一的花柱,柱头从合生花柱顶端远轴面分化形成。 3. 解剖学 在光学显微镜和扫描电子显微镜下,观察了绣球族9属42种1变种及近缘8属11种共53种1变种的叶表皮特征。发现气孔的分布、气孔器的类型、表皮细胞的形状及其垂周壁式样、毛被等具有一定的系统学意义和分类价值。绣球族各属的气孔仅散生于下表皮;而在绣球族的几个近缘属中,上下表皮均有气孔分布。气孔器在多数类群中为无规则型,仅常山属和绣球属离瓣组的成员为平列型。气孔多为椭圆形,稀近圆形;外拱盖表面通常光滑,仅在钻地风属中具条状纹饰;外拱盖内缘具环状加厚,近全缘、不规则波状或浅波状。表皮细胞在多数种中为不规则形,垂周壁波状、浅波状或深波状;在有些种中为(近)多边形,垂周壁平直或弓形。叶表皮细胞形状、垂周壁式样在绣球族寡种属属级水平比较稳定,但在绣球属中变化较大。表皮角质膜纹饰形态多样,有网纹、粗网纹、浅波状条纹、波状条纹、条纹、粗条纹及丝状条纹;在钻地风属及绣球属的少数种中,角质膜条纹有时汇集呈球形或玫瑰型。表皮毛状附属物有单细胞2分枝毛(黄山梅属)、多细胞星状毛(星毛冠盖藤)、单细胞星状毛(溲疏属)和单细胞不分枝毛四种。对钻地风属所有种的观察结果表明,仅在椭圆钻地风的下表皮细胞中央观察到乳突状结构,而在白背钻地风和圆叶钻地风中并未观察到前人描述的附属物。 4. 叶绿体DNA trnL-F序列的分析 首次对绣球族9属23种及近缘类群3属3种的trnL-F序列进行了测定。序列长度在860 bp~970 bp范围内变化。在以山梅花属、溲疏属和黄山梅属为外类群,基于trnL-F序列构建的系统树上,绣球族作为一个单系群得到很高的支持率。绣球属的种出现在不同的分支上,表明该属不是一个单系群。绣球族被分为两大支:第一支由绣球属离瓣组的中国绣球、绣球、以及常山和Broussaisia arguta组成;第二支由绣球属另外的9个种与草绣球属、叉叶蓝属、蛛网萼属、赤壁木属、冠盖藤属以及钻地风属组成。在第二支中,下列类群的近缘关系得到支持:① 草绣球与叉叶蓝属;② 绣球属挂苦子组的东陵绣球、圆锥绣球和挂苦绣球。③ 钻地风属、赤壁木属和冠盖藤属;④ 蜡莲绣球、莼兰绣球、马桑绣球、粗枝绣球。 5. 分支分析 以山梅花属为外类群,基于形态、解剖、花发育、孢粉等32个性状(或性状状态)对绣球族9属的系统发育关系进行了分支分析。结果表明:草绣球属和叉叶蓝属为基出类群,这两个属有多个共同特征;绣球族其余的成员聚成一支,该支又有5个分支。其中蛛网萼属和绣球属冠盖组各为单独的分支,它们有多个自衍征,可能有各自独立的演化线;绣球属离瓣组与常山属聚成一分支,二者的密切关系得到解剖学证据的支持;绣球属绣球组和星毛组聚成一分支,这两个组包含了绣球属的多数种类;钻地风属、赤壁木属、冠盖藤属、Broussaisia和绣球属挂苦子组聚成一分支。其中钻地风属、赤壁木属与冠盖藤属具多个近裔衍征,表明它们是绣球族的晚出类群。 通过对绣球族植物外部形态、花器官发生、叶表皮微形态特征、叶绿体DNA trnL-F区的研究以及基于形态性状的分支分析,并综合已有的研究结果,我们认为: 1. 绣球族是一个单系群;绣球属不是一个单系群。 2. 在绣球族中,草绣球属和叉叶蓝属关系密切,它们可能是绣球族其余成员的姐妹群。 3. 绣球组和星毛组可能是绣球属的核心成员;离瓣组和常山属关系密切;冠盖组有单独的演化线。 4. 赤壁木属、冠盖藤属和钻地风属为单系群,它们在绣球族处于较高的演化位置。 5. 绣球属需重新界定。
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We employed ultrasonic transmitters to follow (for up to 48 h) the horizontal and vertical movements of five juvenile (6.8–18.7 kg estimated body mass) bluefin tuna (Thunnus thynnus) in the western North Atlantic (off the eastern shore of Virginia). Our objective was to document the fishes’ behavior and distribution in relation to oceanographic conditions and thus begin to address issues that currently limit population assessments based on aerial surveys. Estimation of the trends in adult and juvenile Atlantic bluefin tuna abundance by aerial surveys, and other fishery-independent measures, is considered a priority. Juvenile bluefin tuna spent the majority of their time over the continental shelf in relatively shallow water (generally less then 40 m deep). Fish used the entire water column in spite of relatively steep vertical thermal gradients (≈24°C at the surface and ≈12°C at 40 m depth), but spent the majority of their time (≈90%) above 15 m and in water warmer then 20°C. Mean swimming speeds ranged from 2.8 to 3.3 knots, and total distance covered from 152 to 289 km (82–156 nmi). Because fish generally remained within relatively con-fined areas, net displacement was only 7.7–52.7 km (4.1–28.4 nmi). Horizontal movements were not correlated with sea surface temperature. We propose that it is unlikely that juvenile bluefin tuna in this area can detect minor horizontal temperature gradients (generally less then 0.5°C/km) because of the steep vertical temperature gradients (up to ≈0.6°C/m) they experience during their regular vertical movements. In contrast, water clarity did appear to influence behavior because the fish remained in the intermediate water mass between the turbid and phytoplankton-rich plume exiting Chesapeake Bay (and similar coastal waters) and the clear oligotrophic water east of the continental shelf.
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本发明涉及眼镜王蛇毒蛋白酶抑制剂及其衍生物,与其它天然来源小分子量蛋白酶抑制剂相比,具有结构简单、基因表达产量高、活性特殊的有益特点。本发明眼镜王蛇毒蛋白酶抑制剂的制备方法可以是从蛇毒粗毒进行分离纯化获得,也可以通过基因工程表达获得。本发明还提供眼镜王蛇毒蛋白酶抑制剂及其衍生物的应用,其具有同时抑制胰蛋白酶以及胰凝乳蛋白酶的双重抑制活性,且对二种蛋白酶的抑制常数基本在同一个数量级,还具有钠通道的抑制活性。
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A brief description is given of the milkfish (Chanos chanos) farming industry in the Philippines. Over the past 20 years, the relative importance of milkfish has declined with the expansion of tilapia, tiger shrimp and seaweed farming. In 1975, some 141,461 mt of milkfish made up 10% of the total fish production, whereas in 1995, the total milkfish harvest of 150,858 mt made up only 5.5% of the total fish production. Milkfish are harvested and marketed mostly fresh or chilled, whole or deboned, but some are canned or smoked. The domestic markets, mainly in Metro Manila, absorb most of the production. Milkfish is also absorbed in different product forms: dried, canned, smoked, or marinated. An export market for quick-frozen deboned milkfish fillets has begun to develop and fish processing companies are responding fast. The milkfish farming industry has important linkages with the various sectors that supply the inputs, and those that transport, store, market or process the harvest. For intensive milkfish farming to be both profitable and sustainable, more value-added products must be developed and marketed.
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Hybrid glass-carbon 2D braided composites with varying carbon contents are impacted using a gas gun by impactors of masses 12.5 and 44.5. g, at impact energies up to 50. J. The damage area detected by ultrasound C-scan is found to increase roughly linearly with impact energy, and is larger for the lighter impactor at the same impact energy. The area of whitening of the glass tows on the distal side corresponds with the measured C-scan damage area. X-ray imaging shows more intense damage, at the same impact energy, for a higher-mass impactor. Braids with more glass content have a modest increase in density, decrease in modulus, and reduction in the C-scan area and dent depth at the impact site, particularly at the higher impact energies. Impact damage is found to reduce significantly the compressive strength, giving up to a 26% reduction at the maximum impact energy. © 2012 Elsevier Ltd.
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研究了稀土元素Ce4+对铜绿微囊藻生长效应及其被铜绿微囊藻富集的动力学过程。结果表明:当Ce4+的添加浓度小于0.2mg/L时,对铜绿微囊藻的生长有促进作用,当Ce4+的添加浓度大于0.2mg/L时铜绿微囊藻的生长受到抑制。Ce4+在铜绿微囊藻中富集的动力学过程可用二级吸附动力学模型表征。
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The present study was carried out to investigate the influence of water temperature on the growth performance and digestive enzyme (pepsin, trypsin and lipase) activities of Chinese longsnout catfish. Triplicate groups of Chinese longsnout catfish (35.6 +/- 0.48 g, mean +/- SE) were reared at different water temperatures (20, 24, 28 and 32 degrees C). The feeding rate (FR), specific growth rate (SGR) and feed efficiency ratio (FER) were significantly affected by water temperatures and regression relationships between water temperature and FI, SGR as well as FER were expressed as FR=-0.016T2+0.91T-10.88 (n=12, R2=0.8752), SGR=-0.026T2+1.39T-17.29 (n=12, R2=0.7599) and FER=-0.013T2+0.70T-8.43 (n=12, R2=0.7272). Based on these, the optimum temperatures for FR, SGR and FER were 27.66, 26.69 and 26.44 degrees C respectively. The specific activities of digestive enzymes at 24 or 28 degrees C were significantly higher than that at 20 or 32 degrees C. In addition, there was a significant linear regression between FR or SGR and specific activities of pepsin and lipase, which indicated that pepsin and lipase played important roles in regulating growth through nutrient digestion in Chinese longsnout catfish.