892 resultados para tooth attrition


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角蟾科(Megophryidae)是以角蟾属(Megophrys Kuhl and Van Hasselt, 1822)为模式属而建立的,隶于无尾目(Anura),变凹型亚目(Anomocoela)。角蟾科包括2 亚科11 属142 种,分布于东洋界,从巴基斯坦、中国西部向东直到菲律宾和苏达群岛;中国有9 属75 种分布于华中和华南地区。角蟾科被认为是原始的两栖动物之一,其分类学、系统学、生态学、动物地理学的研究均深受中外科学家的瞩目。近年来,通过形态学、古生物学、细胞学、生态学、支序系统学的研究,角蟾科的分类与系统学研究取得了较大进展。与成体形态和分子系统学研究结果相比较,蝌蚪的研究存在更多的问题和挑战,尚需深入研究:(1)角蟾科蝌蚪的形态多样性分析;(2)角蟾科的系统发育关系与蝌蚪的演化,以及口漏斗的起源;(3)角蟾科蝌蚪表型分化与栖息环境和觅食行为的适应演化。针对上述问题,本文对角蟾科9 属30 种蝌蚪的形态特征,包括外部宏观形态和口器外部结构特征、口器内部显微结构、唇齿和角质颌的亚显微结构作了深入细致、多层次的比较研究;通过12s rRNA 和cytochrome b 基因构建最大简约树,采用贝叶斯系统发育进行分析,蝌蚪型的演化采用祖先性状的重建方法分析;得到如下结论:1)初步将角蟾科蝌蚪分为4 种类型;并且建立了2 种新的角蟾科蝌蚪类型。A 型:拟髭蟾型蝌蚪,该型蝌蚪包括拟髭蟾属、髭蟾属、齿蟾属和齿突蟾属的物种;B 型:新类型,掌突蟾型蝌蚪,该型蝌蚪在本文中包括掌突蟾属、小臂蟾属的物种;C 型:新类型,短腿蟾型蝌蚪,一种特化类型,该型蝌蚪在本文中仅包括短腿蟾属的物种;D 型:角蟾型蝌蚪,该型蝌蚪在本文中包括无耳蟾属、小口拟角蟾属和异角蟾属的物种。2)对角蟾科的分类进行了修订:(1)支持角蟾科两个亚科的分类系统;(2)角蟾亚科包括拟角蟾属、异角蟾属、无耳蟾属和短腿蟾属;该亚科形态差异小,系统学关系比较复杂,暂不作族级分类的再划分;(3)拟髭蟾亚科分为2 个族:拟髭蟾族,该族物种具有类型A 的蝌蚪,包括4 个属:拟髭蟾属、髭蟾属、齿蟾属、齿突蟾属;掌突蟾族,该族物种具有类型B 的蝌蚪,包括2 个属:掌突蟾属和小臂蟾属。3)结合分子系统进化关系探讨了4 种蝌蚪类型的演化。(1)角蟾科蝌蚪的最近共同祖先来自于一类具有拟髭蟾型蝌蚪性状的蝌蚪;(2)掌突蟾型蝌蚪和角蟾亚科的蝌蚪是由具有拟髭蟾型蝌蚪性状的祖先蝌蚪分别演化而来;(3)短腿蟾型蝌蚪是角蟾型蝌蚪的一种特化类型;(4)外群蝌蚪具有与拟髭蟾型蝌蚪相似的性状,进一步印证了类拟髭蟾型蝌蚪是角蟾科蝌蚪的最近共同祖先的假说;(5)具有口漏斗的蝌蚪类型是由不具口漏斗的蝌蚪类型演化而来,在角蟾科中口漏斗是一种衍生性状。4)分析了角蟾科四种蝌蚪类型与栖息环境的适应演化。(1)角蟾科蝌蚪的口部和体形的变化反映了该科蝌蚪由缓流向类似静水生境的回水凼的渐变式适应,角蟾科蝌蚪的形态显示了多方面的适应变化;(2)随着蝌蚪类型由A 向D的演化,当水速较大时,拟髭蟾型的蝌蚪营流水攀吸型生活方式;当水速递减时,掌突蟾型蝌蚪营流水附着型生活方式;当水速进一步递减时,具有较小口漏斗的短腿蟾型蝌蚪和具有大漏斗的角蟾型蝌蚪营流水浮泳型生活。角蟾科蝌蚪对于水流递减的适应演化说明蝌蚪的生态学适应是具有进化意义的;(3)蝌蚪口器内部结构的分化揭示了蝌蚪和食性的适应关系,蝌蚪以口部的唇齿与角质颌刮取或吞吸水中的物质,然后,通过口乳突有选择地过滤进入口腔中食物。拟髭蟾亚科蝌蚪的唇齿多而窄,唇齿间距宽,颌鞘粗而稀,反映了其植食性为主的特点;它们的舌前乳突一般为指状,在口腔入口处所占面积小,其机械过滤的作用很多被唇齿和角质颌分担了;而角蟾亚科的蝌蚪,其角质颌弱,其舌前乳突一般为匙状,几乎填满了口腔入口处,因此舌前乳突起了主要的机械过滤作用。The family Megophryidae is the largest and most diverse families inArchaeobatrachia, and most of its species occur in India, Pakistan, and eastward intoChina, Southeast Asia, Borneo and the Philippines to the Sunda Islands. Currently thefamily includes 142 species have been grouped into two subfamilies, Megophryinaeand Leptobrachiinae. The mountains of central and southern China are rich in speciesof Megophryidae, 75 species belong to 9 genera and two subfamilies.The family was supposed to be ideal materials of studies in many fields of biology,such as taxonomy, evolution, systematics, ecology, and biogeography. Recently, therehave a great development in taxonomy and systematics of megophryids throughstudied by morphology, paleontology, cytology, ecology, and cladistics. However,larvae of megophryids were generally unknown, although the tadpoles might be veryimportant for above studies.In this paper, we examined the evolutionary scenario of the tadpoles’ morphologyin the context of a phylogenetic framework. Our objectives are (1) to evaluate thedivergence of larval body shape and oral discs in the family Megophryidae, (2) toexplore the evolutionary trends of the larvae in megophryidae, and test if thefunnel-shaped oral disc is apomorphic, and (3) to explore the relationship of the larvalstructure, diet and microhabitat.We examined larval morphology of 30 megophryid species, the larval body shape,oral discs, the buccopharyngeal cavity, and jaw sheaths and denticles of the Chinesemegophryid frogs were re-examined. We constructed a phylogeny of the species on thebasis of published mitochondrial cytochrome b and 16S rRNA gene segments usingpartitioned Bayesian analyses. Furthermore, hypothetical changes of larval morphologywere inferred using parsimony principle on the phylogeny. The results showed that:1) Four tadpole types in Megophryidae. The larval morphological charactersseries in Chinese megophryids fall into four general categories according to the bodyshape and oral discs: (A) Leptobrachiini type, species from genera Leptobrachium,Oreolalax, Scutiger and, Vibrissaphora share this type of tadpoles. (B) Leptolalax type,species of genus Leptolalax have this type of tadpoles. (C) Brachytarsophrys type,species of the genus Brachytarsophrys have this type of tadpoles. (D) Megophryinitype, species of the genera Atympanophrys, Ophryophryne, and Xenophrys share this type of tadpoles. Of which B and C are two novel types.2)Taxonomic implications. The present study leads us to reconsider the generalclassification of tribes attributed to members of Megophryidae. More specifically,concerning the phylogenetic relationships and the two novel tadpole types describedherein, we propose a provisional taxonomy for the family but suggest that further taxasampling of other megophryids be performed to confirm this taxonomic change. TheMegophryidae is composed of two subfamilies (Leptobrachiinae and Megophryinae).The Leptobrachiinae was recogonized the two tribes: (1) tribe Leptobrachiini sensuDubois, corresponding to the tadpole of type A, including four genera, i.e.,Leptobrachium, Oreolalax, Scutiger and, Vibrissaphora; (2) tribe Leptolalaxini,corresponding to the tadpole of novel type B, including two genera, i.e., Leptolalaxand Leptobrachella. However, the relationships among the genera of Megophryinaewere largely unresolved, they recognized no monophyletic groups above the generalevel. A more thorough sampling will likely foster a better taxonomic solution.3) The larval evolutionary scenario in Megophryidae.Type A is characteristicof normal-mouthed with multiple tooth rows, representing the tadpole type of theMRCA of Chinese megophryids. Type B is characteristic of normal-mouthed withreduced tooth rows, prolonging labium, and integumetary glands. Type C ischaracteristic of no labial teeth and smaller umbeliform oral disc. Type D ischaracteristic of no labial teeth, enlarged umbeliform oral disc, representing the tadpoleof the MRCA of subfamily Megophryinae. A previous hypothesis, referring tofunnel-shaped oral discs as an apomorphy, is supported.4) The larval adaptation to habitats in Megophryidae. Tadpoles generallyadhere to substrates using their mouths, and the microhabitat that the tadpoles occupyreflects the degree of adhesion and oral complexity. The morphological changes inmegophryid tadpoles virtually allow a progressive adaptation to a changing habitatfrom faster water to slower water. Within the tadpoles of Type A to type D, the TOTbecomes smaller and smaller, and the oral disc orientates from anteroventral toumbelliform upturned, and eye position orientates from dorsal to lateral, and the trunkis more and more depressed and tail becomes relatively longer and slender. Within therunning water, the normal-mouthed with multiple tooth rows of Leptobrachiini tadpoles are correlated with lotic-suctorial, benthic feeders with anteroventral oraldisc and the largest body. With the water’s velocity decreasing, the lotic-adherentfeeders of Leptolalax tadpoles have tube-shaped labium with reduced tooth rows andintegumetary glands. And then, the smaller umbeliform in Brachytarsophrys tadpolesand the enlarged umbeliform oral disc in the Megophryini tadpoles are inhabitmicrohabitats of non-flowing backwaters of rivers, indicative of adaptive traits oflotic-neustonic surface feeders. The scheme of megophryid tadpoles andmicrohabitats provided the first clear evidence which congruent with the hypothesis ofAltig and Johnston (1989). The ecological divergence plays a general role in thedivergence and evolution of megophrid larvae. There is a definite correlation amongthe buccopharyngeal cavity, diet and feeding mechanisms, the tadpole graze orswallow the food particles, then through papillae which like a sieve and sort out foodparticles to the oesophagus. The tadpole of Leptobrachiinae possess multiple toothrows, wide intertooth distance as well as thick and sparse jaw sheath, these tadpolesinhabit bottom of the streams and graze on epiphyton or major detritus of organicmatter on the substrates, their prelingual papillae like single finger, the mechanicalpurpose of papillae served share in by tooth and jaw. The tadpoles of Megophryinaeoccur near the water surface of small streams and are the filter feeder, their dietincludes plankton and organic debris floating on the water surface, those tadpolepossess weak jaw, their prelingual papillae like spoon, the mechanical purpose ofpapillae served mostly for sieve.

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A new species, Axianassa sinica, from the Beibu Gulf (Gulf of Tonkin), northern South China Sea, is described and illustrated. The new species is readily distinguished from A. australis Rodrigues & Shimizu, 1992, by its acute rostrum, merus of pereopod 1 with a tooth distally on lower margin and an elongated telson.

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A number of proxy records of paleoenvironment using stable isotopes could show the history of past environmental changes. These archives include peat and lake sediments, loess-paleosot sequence, fossil mammals and stalagmite, and so on. The stable isotopic composition of carbonate and organic matter and frequency magnetic susceptibility from Tianshuigou and Yuanlei loess-palesol sequence can be used to give estimates of the paleoenvironmental history of Dali, and even of the whole Chinese Loess Plateau during the last 250ka. Features of the High Temperature and Large Precipitation Event in the Tibet Plateau and its adjacent area during 40~30kaBP had been studied by Professor Shi Y. In this dissertation, its impact on Chinese Loess Plateau has been discussed again. Carbon and oxygen isotopic ratios, magnetic susceptibility and frequency magnetic susceptibility in Tianshuigou and Yuanlei profiles show that the Event in this area is not so stronger as the Tibet Plateau. The carbon isotopic composition of organic matter in Tianshuigou, Yuanlei, dingcun and Jingcun loess-palesol sequences are indicative of major changes in the paleovagetation between terrace and plain of the Chinese Loess Plateau. Water is one of the most important factors adjusting the relative biomass of C4 plant in terrestrial ecosystems. Stable carbon isotope ratio of vertebrate tooth enamel is used increasingly to reconstruct environmental and ecological information modern and ancient ecosystems. The SI3C value of tooth enamel bioapatites can distinguish between browsers and grazers. Data from typical grassland of Inter Mongolia, the Alpine meadow of Qinghai-Tibet Plateau and the Yaluzangbu Great Canyon indicate that diets of mammals could record the relative biomass of C4 plant only in the C4 dominated ecosystem. In a C3 dominated ecosystem, diet of mammals would include more C3 plants than vegetation. According to Professor Cerling, proxy records from North and South America, Africa and Pakistan show that at the end of the Miocene (between 8Ma to 6 Ma) there was a global expansion of CA biomass, probably when atmospheric CO2 levels declined. Thus, "C4 world" and "CO2 starvation" are put forward. In this dissertation, carbon isotopes of fossil tooth such as Equus sanmeniensis and Hipparion chiai from Linxia, China reveal that there is a C3 dominated ecosystem in the late Miocene. Diets of ancient mammals in Linxia are not evidence of global expansion of C4 biomass.

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The carbon isotope compositions of plants in Xilinguole, Haibei and Jilong and the tooth enamel of animals in Jilong have been analyzed. The study of carbon isotope discrimination of plants along altitude gradient among the three areas has found decreased discrimination.The eolian deposits of Heyeping can be used to reconstruct Holocene climate variability in the region. Some proxies indicates that the 8. 2 ka event can be found in north China, and it is warm and arid in the 4900~6800(or 6900) cal. a BP.

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In my research, I have performed an extensive experimental investigation of harmonic-drive properties such as stiffness, friction, and kinematic error. From my experimental results, I have found that these properties can be sharply non-linear and highly dependent on operating conditions. Due to the complex interaction of these poorly behaved transmission properties, dynamic response measurements showed surprisingly agitated behavior, especially around system resonance. Theoretical models developed to mimic the observed response illustrated that non-linear frictional effects cannot be ignored in any accurate harmonic-drive representation. Additionally, if behavior around system resonance must be replicated, kinematic error and transmission compliance as well as frictional dissipation from gear-tooth rubbing must all be incorporated into the model.

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BackgroundMechanical ventilation is important in caring for patients with critical illness. Clinical complications, increased mortality, and high costs of health care are associated with prolonged ventilatory support or premature discontinuation of mechanical ventilation. Weaning refers to the process of gradually or abruptly withdrawing mechanical ventilation. the weaning process begins after partial or complete resolution of the underlying pathophysiology precipitating respiratory failure and ends with weaning success (successful extubation in intubated patients or permanent withdrawal of ventilatory support in tracheostomized patients).ObjectivesTo evaluate the effectiveness and safety of two strategies, a T-tube and pressure support ventilation, for weaning adult patients with respiratory failure that required invasive mechanical ventilation for at least 24 hours, measuring weaning success and other clinically important outcomes.Search methodsWe searched the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 6); MEDLINE (via PubMed) (1966 to June 2012); EMBASE (January 1980 to June 2012); LILACS (1986 to June 2012); CINAHL (1982 to June 2012); SciELO (from 1997 to August 2012); thesis repository of CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior) (http://capesdw.capes.gov.br/capesdw/) (August 2012); and Current Controlled Trials (August 2012).We reran the search in December 2013. We will deal with any studies of interest when we update the review.Selection criteriaWe included randomized controlled trials (RCTs) that compared a T-tube with pressure support (PS) for the conduct of spontaneous breathing trials and as methods of gradual weaning of adult patients with respiratory failure of various aetiologies who received invasive mechanical ventilation for at least 24 hours.Data collection and analysisTwo authors extracted data and assessed the methodological quality of the included studies. Meta-analyses using the random-effects model were conducted for nine outcomes. Relative risk (RR) and mean difference (MD) or standardized mean difference (SMD) were used to estimate the treatment effect, with 95% confidence intervals (CI).Main resultsWe included nine RCTs with 1208 patients; 622 patients were randomized to a PS spontaneous breathing trial (SBT) and 586 to a T-tube SBT. the studies were classified into three categories of weaning: simple, difficult, and prolonged. Four studies placed patients in two categories of weaning. Pressure support ventilation (PSV) and a T-tube were used directly as SBTs in four studies (844 patients, 69.9% of the sample). in 186 patients (15.4%) both interventions were used along with gradual weaning from mechanical ventilation; the PS was gradually decreased, twice a day, until it was minimal and periods with a T-tube were gradually increased to two and eight hours for patients with difficult and prolonged weaning. in two studies (14.7% of patients) the PS was lowered to 2 to 4 cm H2O and 3 to 5 cm H2O based on ventilatory parameters until the minimal PS levels were reached. PS was then compared to the trial with the T-tube (TT).We identified 33 different reported outcomes in the included studies; we took 14 of them into consideration and performed meta-analyses on nine. With regard to the sequence of allocation generation, allocation concealment, selective reporting and attrition bias, no study presented a high risk of bias. We found no clear evidence of a difference between PS and TT for weaning success (RR 1.07, 95% CI 0.97 to 1.17, 9 studies, low quality of evidence), intensive care unit (ICU) mortality (RR 0.81, 95% CI 0.53 to 1.23, 5 studies, low quality of evidence), reintubation (RR 0.92, 95% CI 0.66 to 1.26, 7 studies, low quality evidence), ICU and long-term weaning unit (LWU) length of stay (MD -7.08 days, 95% CI -16.26 to 2.1, 2 studies, low quality of evidence) and pneumonia (RR 0.67, 95% CI 0.08 to 5.85, 2 studies, low quality of evidence). PS was significantly superior to the TT for successful SBTs (RR 1.09, 95% CI 1.02 to 1.17, 4 studies, moderate quality of evidence). Four studies reported on weaning duration, however we were unable to combined the study data because of differences in how the studies presented their data. One study was at high risk of other bias and four studies were at high risk for detection bias. Three studies reported that the weaning duration was shorter with PS, and in one study the duration was shorter in patients with a TT.Authors' conclusionsTo date, we have found evidence of generally low quality from studies comparing pressure support ventilation (PSV) and with a T-tube. the effects on weaning success, ICU mortality, reintubation, ICU and LWU length of stay, and pneumonia were imprecise. However, PSV was more effective than a T-tube for successful spontaneous breathing trials (SBTs) among patients with simple weaning. Based on the findings of single trials, three studies presented a shorter weaning duration in the group undergoing PS SBT, however a fourth study found a shorter weaning duration with a T-tube.

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Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em em Biotecnologia e Saúde, Epidemiologia e Saúde Pública.

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Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária.

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Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária

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Monografia apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em Medicina Dentária

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Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária.

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária