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31.
The selective pressures associated with flight are significant factors in shaping the morphology of volant forms. Tropical seabirds are of particular interest because of their long foraging bouts, which can last hundreds of kilometers in search of unpredictable (spatially and temporally) resources. Here, we contrast wing loading (WL), aspect ratio (AR), and planform shape among five pelecaniform seabirds and correlate morphological diversity with known differences in flight strategies. Overall, WL and AR scaled with body mass. The Great Frigratebird had lower WL than that predicted, whereas the Red-tailed Tropicbird had higher WL than that predicted. The tropicbird also exhibited a lower AR than that predicted. Visualization of planform shape was accomplished by using Thin-plate spline relative warp analysis (TPS/RWA), and three major regions of variations were discovered: wing base, mid-wing, and distal wing/wing tip. As expected, the three boobies were more similar than either the tropicbird or the frigatebird. The tropicbird had a broader distal wing and more rounded wing tip, associated with its greater use of flapping flight. The frigatebird showed the greatest deviation in the distal wing and wing tip associated with the high maneuverability required for aerial pursuit and kleptoparasitism. By using TPS/RWA, important differences were detected in planform shape that would have otherwise gone unnoticed when using only WL and AR. These differences correlated strongly with parameters such as maneuverability, flapping, and soaring flight. 相似文献
32.
Sedat Altug Orhan Uludag Bahar Tunctan Iclal Cakici Hakan Zengil 《Chronobiology international》2013,30(3):583-591
We previously demonstrated the rhythmic pattern of L‐arginine/nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) cascade in nociceptive processes. The coupled production of excess NO and superoxide leads to the formation of an unstable intermediate peroxynitrite, which is primarily responsible for NO‐mediated toxicity. In the present study, we evaluated the biological time‐dependent effects of exogenously administered peroxynitrite on nociceptive processes and peroxynitrite‐induced changes in the analgesic effect of morphine using the mouse hot‐plate pain model. Experiments were performed at four different times of day (1, 7, 13, and 19 hours after lights on, i.e., HALO) in mice of both sexes synchronized to a 12 h:12 h light‐dark cycle. Animals were injected intraperitoneally (i.p.) with saline or 10 mg/kg morphine 30 min before and 0.001 mg/kg peroxynitrite 30 sec before hot‐plate testing, respectively. The analgesic effect of morphine exhibited significant biological time‐dependent differences in the thermally‐induced algesia; whereas, administration of peroxynitrite alone exhibited either significant algesic or analgesic effect, depending on the circadian time of its injection. Concomitant administration of peroxynitrite and morphine reduced morphine‐induced analgesia at three of the four different study time points. In conclusion, peroxynitrite displayed nociceptive and antinociceptive when administered alone according to the circadian time of treatment, while it diminished analgesic activity when administered in combination with morphine at certain biological times. 相似文献
33.
A new species of Psychodidae, Syntomoza amaliae is described from Nicaragua and compared to all the type material of this genus. Besides head and wing structures, the subgenital plates provide taxonomic characters by which the ♀ ♀ can be determined. Drawings of the respective details are presented for 4 neotropical Syntomoza species. 相似文献
34.
Mazoyerella gen. nov., based on Corynospora arachnoidea Harvey from Tasmania, is placed provisionally in the Compsothamnieae tribe of the Ceramiaceae. All plants can produce elongate-ovoid monosporangia which reproduce the same phase. Sporophytes also bear polysporangia and sexual plants are dioecious, bearing either spermatangial heads or subterminal procarps followed by carposporophytes with nearly all gonimoblast cells becoming carposporangia and an involucrum of sterile filaments developing from sterile cells associated with the procarp. The life-history has been followed through successive generations in culture. 相似文献
35.
洋蒲桃次生木质部中导管分子的解剖学 总被引:6,自引:0,他引:6
运用细胞图像分析系统和显微照相的方法对洋蒲桃(Syzygium samarangense)次生木质部导管分子进行了观察研究。次生木质部导管分子类型有:两端具尾导管、一端具尾导管和无尾导管。导管分子穿孔板存在着4种类型:两端均为具2个单穿孔的复穿孔板;一端为1个单穿孔板,另1端为具2个单穿孔的复穿孔板;两端均为单穿孔板:两单穿孔板位于同一端壁两侧相互对应以及一些过渡类型穿孔板。根据观察结果,分析了各类型穿孔板之间的演化关系。 相似文献
36.
Shi Wei-ping Ren Lu-quan Tian Li-mei 《仿生工程学报(英文版)》2005,2(3):145-150
Adhesive forces exist between soil and the surfaces of soil-engaging components; they increase working resistance and energy consumption. This paper tries to find an approach to reduce the adhesion and resistance of bulldozing plate. A simplified mechanical model of adhesion and resistance between soil and a non-smooth bulldozing plate is proposed. The interaction force between moist soil and a non-smooth bulldozing plate is analyzed. The pressure and friction distribution on the bulldozing plate are computed, and the anti-adhesive effect of a corrugated bulldozing plate is simulated numerically. Numerical results show that the wavy bulldozing plate achieves an effective drag reduction in moist soil. The optimal wavy shape of the corrugated bulldozing plate with the minimal resistance is designed. The basic principle of reducing soil adhesion of the non-smooth surface is discovered. 相似文献
37.
Robert A. Fenton Wing‐Kee Lee Frank Thévenod Craig P. Smith 《Journal of cellular and molecular medicine》2011,15(2):209-219
Ferroportin 1 (FPN1) is an iron export protein expressed in liver and duodenum, as well as in reticuloendothelial macrophages. Previously, we have shown that divalent metal transporter 1 (DMT1) is expressed in late endosomes and lysosomes of the kidney proximal tubule (PT), the nephron segment responsible for the majority of solute reabsorption. We suggested that following receptor mediated endocytosis of transferrin filtered by the glomerulus, DMT1 exports iron liberated from transferrin into the cytosol. FPN1 is also expressed in the kidney yet its role remains obscure. As a first step towards determining the role of renal FPN1, we localized FPN1 in the PT. FPN1 was found to be located in association with the basolateral PT membrane and within the cytosolic compartment. FPN1 was not expressed on the apical brush‐border membrane of PT cells. These data support a role for FPN1 in vectorial export of iron out of PT cells. Furthermore, under conditions of iron loading of cultured PT cells, FPN1 was trafficked to the plasma membrane suggesting a coordinated cellular response to export excess iron and limit cellular iron concentrations. 相似文献
38.
Smith LG 《Current opinion in plant biology》1999,2(6):447-453
Plant cells divide in two by constructing a new cell wall (cell plate) between daughter nuclei after mitosis. Golgi-derived vesicles are transported to the equator of a cytoskeletal structure called a phragmoplast, where they fuse together to form the cell plate. Orientation of new cell walls involves actindependent guidance of phragmoplasts and associated cell plates to cortical sites established prior to mitosis. Recent work has provided new insights into how actin filaments and other proteins in the phragmoplast and cell plate contribute to cytokinesis. Newly discovered mutations have identified a variety of genes required for cytokinesis or its spatial regulation. 相似文献
39.
Hangil Chang Naohide Yamashita Hiroshi Matsunaga Kiyoshi Kurokawa 《The Journal of membrane biology》1988,103(3):263-271
Summary We have previously reported hyperpolarizing membrane potential changes in a monkey kidney cell line (JTC-12) which has characteristics resembling proximal tubular cells. These hyperpolarizations could be observed spontaneously or evoked by mechanically touching adjacent cells. In this report, we have shown further evidence that these hyperpolarizations are elicited by an increase in membrane conductance to K+ which is caused by an increase in cytosolic Ca2+ concentration. In addition, we have found another type of hyperpolarization which is evoked by applying flow of extracellular fluid to the cell. Intracellular injection of Ca2+ and Sr2+ evoked hyperpolarizations, while intracellular injection of Mn2+ and Ba2+ did not. Intracellular injection of EGTA suppressed both spontaneous and mechanically evoked hyperpolarizations. In Ca2+-free medium, both spontaneous and flow-evoked hyperpolarizations were not observed, while mechanical stimuli consistently evoked hyperpolarization. In Na+-free medium, the incidence of cells showing the spontaneous or flow-evoked hyperpolarization increased, and the amplitude and the duration of the mechanically evoked hyperpolarization became greater. Quinidine inhibited all types of hyperpolarization. These data suggest that hyperpolarizations in JTC-12 cells are due to an increase in Ca2+-activated K+ conductance. 相似文献
40.
摘要 目的:探讨老年踝关节骨折患者的内固定方式的选择情况及不同内固定方式的疗效,进而指导临床医师根据患者的具体情况选择合适的内固定方式。方法:本研究为回顾性研究,选取我院2016年1月~2018年12月期间收治的老年踝关节骨折患者40例作为研究对象,统计患者一般情况,内容包括骨折块情况、骨折类型、骨质疏松情况、软组织情况与体质。术后随访12个月,评价所有患者末次随访时的踝关节跖屈度、踝关节背伸度、美国足踝外科协会(AOFAS)踝-后足功能评分,记录所有患者的骨折愈合时间。结果:40例研究对象中,使用克氏针张力带11例,Herbert螺钉10例,解剖锁定钢板7例,解剖复合钢板6例,1/3管型钢板6例。骨折块较小、外踝撕脱性骨折的患者主要应用克氏针张力带;伴有骨质疏松的患者主要应用解剖锁定钢板;软组织条件不佳或受损的患者主要应用Herbert螺钉或1/3管型钢板;超重或肥胖患者主要应用解剖复合钢板;瘦弱患者主要应用1/3管型钢板。末次随访时,5种内固定方式患者的踝关节背伸度、踝关节跖屈度、AOFAS踝-后足功能评分比较未见显著性差异(P>0.05)。5种内固定方式的骨折愈合时间对比差异存在统计学意义(P<0.05)。结论:老年踝关节骨折应根据患者具体情况选择合理的内固定方式,不同内固定方式患者的骨折愈合时间虽存在差异,但最终均可获得较为满意的疗效。 相似文献