九段沙上沙湿地植物N、P、K的分布特征与季节动态

2005年4-12月逐月对长江口九段沙上沙湿地生态系统主要植物进行定位样品采集与生态环境因子监测.通过对该区典型湿地植物群落海三棱蔗草(Scirpusmariqueter)、互花米草(Spartina aherniflora)和芦苇(Phragmites australis)3种植物样品中N、P、K元素含量的分析,揭示了上沙主要类型湿地植物N、P、K元素的分布特征与季节变化规律.结果表明:3种湿地植物N、P、K元素分布特征不同,不同植物以及同一植物的不同构件营养元素含量随植物生长节律发生变化.植物中元素贮量与含量之间分布特征并不相同,其原因主要在于生物量是制约元素贮量的主要因素,N、P、K贮量排序均为芦苇＞互花米草＞海三棱蔗草.不同构件营养元素含量的变化规律存在差异:4-5月茎中K含量逐渐减少,N含量呈现增加趋势;5-6月各构件P含量呈减少趋势;6-10月叶中N含量普遍高于其他构件.     

长江河口九段沙互花米草湿地生态系统N、P、K的循环特征

研究了九段沙外来入侵种互花米草（Spartina alterniflora）湿地生态系统的营养元素含量、分布规律与循环特征。结果表明,九段沙的上沙、中沙和下沙互花米草湿地土壤全量养分含量差异相对较小,而速效性养分含量差异相对较大。土壤剖面中TK含量大大高于TN和TP含量,排序为:TK＞TN＞TP。各沙洲速效性养分含量排序为：速效K＞速效N＞速效P。土壤速效性养分与全量养分的空间分布规律并不一致,土壤剖面营养元素的垂直分布差异比较明显,速效性养分土壤剖面垂直分异比全量养分显著。各深度土壤营养元素含量均存在差异,不同沙洲同一深度土壤营养元素含量也存在差异。各沙洲不同深度土壤TN含量的差异明显大于TP和TK含量差异。植物中3种营养元素含量以K最高,N其次,P最低。湿地生态系统营养元素归还量远大于存留量。吸收系数排序为：N＞P＞K。不同沙洲营养元素的利用系数和循环系数存在明显差异,上沙P元素、中沙与下沙K元素利用系数最大,上沙K元素、中沙P元素与下沙N元素循环系数最大。     

长江河口九段沙海三棱藨草湿地生态系统N、P、K的循环特征

研究了九段沙海三棱蔗草湿地生态系统的营养元素(N、P、K)的含量特征、分布规律与循环特点.结果表明:随下沙-中沙-上沙海拔高程依次缓慢上升,土壤全剖面中P、K含量逐渐下降,N含量不受海拔高程影响.土壤剖面全量养分TN平均含量排序为:中沙>下沙>上沙;TP与TK排序均为:下沙>中沙>上沙.速效性养分AN含量排序为:中沙>下沙>上沙,AP与AK排序均为:下沙>中沙>上沙.土壤全量与速效性养分排序分别为:TK>TP>TN、AK>AN>AP.随土壤剖面深度增加,营养元素含量呈减少趋势.土壤剖面营养元素分布显示N、K的表聚性比P明显.上沙、中沙与下沙海三棱蔗草湿地植物K和N的吸收量均大于P.海三棱蔗草对土壤营养元素的吸收量排序上沙和下沙均为:K>N>P;中沙为:N>K>P.上沙海三棱蔗草吸收营养元素总量最多,中沙其次,下沙最少.各沙洲海三棱蕨草湿地生态系统的营养元素吸收系数排序为:N>P>K;循环系数排序为:K>N>P.上沙海三棱蔗草湿地生态系统N的利用系数最大,中沙和下沙湿地生态系统K的利用系数最大.     

九段沙芦苇湿地生态系统N、P、K的循环特征

对九段沙(上沙、中沙、下沙)芦苇湿地土壤、植物中N、P、K含量进行了测定,研究其分布规律.结果表明:水平分布上,湿地土壤全量养分与速效性养分含量均是中沙最低,并以中沙为中心向两端递增,速效性养分的这种变化尤为显著.垂直分布上,土壤全N和全K含量的分布规律一致,为上层＞下层＞中层;全P含量分布为中层＞上层＞下层.速效N含量分布为上层＞中层＞下层;速效P含量上层土壤最高,中、下层土壤含量因湿地类型而异;速效K含量多以中层土壤最低,上、下层土壤含量变化不稳定,以不同湿地而异.不同芦苇湿地的土壤速效性养分含量差异显著大于全量养分的差异,0～60 cm深度土壤的全量养分和速效性养分含量排序均为K＞N＞P.中沙湿地植物中养分含量最低,与土壤中营养元素总体水平分布一致;多数芦苇湿地植物中营养元素含量排序为N＞K＞P,与土壤养分含量排序不一致.不同芦苇湿地的吸收系数排序均为N＞P＞K;芦苇湿地利用系数排序为P＞K＞N;循环系数排序为N＞K＞P.     

羊草草原植物-土壤之间主要营养元素动态的研究

羊草草原土壤中N、P、K含量的季节变化规律是生长季初期较高,6—8月生长旺季较低,生长季末再度升高。营养元素在植物体内的分配是地下部分大于地上部分。地下部分N的贮量为地上部分的3.6倍,K为2.9倍,P为2.8倍。地上部分3种元素含量的季节变化曲线呈单峰型,从生长初期开始上升,最大值出现在8月,生长末期逐渐下降。地下部分的季节变化规律,大体上在整个生长季内呈上升趋势,随着根系的生长,营养元素的积累量不断增加。对植物—土壤之间营养元素动态分析结果表明,随着时间的推移,N、P、K在各状态中的比例趋于恒定。在稳定状态下,3种元素在土壤中的比例逐渐减少,与初始量相比N、P、K的含量分别减少21.23%、5.14%和2.99%。在其它状态中,3种元素的含量均有提高,特别在枯枝落叶和死根中增加的幅度较大。     

滨海盐地碱蓬不同生长阶段叶片C、N、P化学计量特征

盐地碱蓬(Suaeda salsa)是滨海湿地典型植被之一, 研究其化学计量特征变化对于了解滨海湿地植被健康状况具有重要意义。该文比较了盐地碱蓬生长期、成熟期和衰退期内叶片C、N、P营养元素的化学计量特征, 并做了相关性分析。结果表明, 叶片C含量在不同生长阶段差异性显著, 生长期最低, 衰退期最高; 叶片N含量在衰退期较生长期和成熟期显著降低; 叶片P含量较为稳定, 在不同生长阶段无显著性差异。C:N、C:P在植物整个生长发育期内呈现逐渐增大的趋势, 而N:P表现出逐渐减小的趋势。相关性分析显示, 在盐地碱蓬3个不同的生长阶段, C:N和C:P与相应的N、P含量呈显著负相关, 随着N、P的变化以对数方程的形式减小; N含量与P含量之间呈显著正相关, 体现了植物体内两营养元素含量需求变化的相对一致性。同时发现, N元素已经成为滨海湿地盐地碱蓬生长发育过程中的主要限制性因子。     

毛果苔草湿地营养元素的积累、分配及其生物循环特征

毛果苔草(Carex lasiocarpa)湿地地上部分积累量小于地下部分的积累量,在地上几个构件中,叶片比叶鞘积累量大,而穗的积累量最小;地下部分中细根比根茎的积累量大.土壤分室营养元素贮量在系统的各分室中占绝对优势,毛果苔草湿地土壤中各种营养元素总贮量的顺序为K＞Fe＞N＞Ca＞P＞Mg＞Mn＞Zn＞Cu;它们的吸收系数的排序是Mn＞N＞P＞Zn＞Mg＞Cu＞Ca＞Fe＞K;几种营养元素的利用系数的排序是Mn＞N＞P＞Zn＞Mg＞Cu＞Ca＞Fe＞K;几种营养元素的循环系数的排序为Ca＞K＞Mg＞N＞P＞Mn＞Zn＞Cu＞Fe;因此,该系统中钙、钾的存留比例最小,而流动性较大,而铁则相反,存留比例大,流动性较小.     

三江平原湿地生态系统P、K分布特征及季节动态研究

对三江平原毛果苔草,狭叶甜茅（Carex lasixarpa-Glyeria spiculosa)湿地和小叶章（Deyeuxia angusti,folia)湿地的值物,土壤和地表积水进行P,K含量测定,运用一元非线性回归分析对P,K元素含量季节动态特征进行了探讨,结果表明,不同种类的湿地植物,同种植物的不同器官其P,K含量存在的差异,但部特点是K含量高于P含量,说明湿地植物具有富集K的特性,两类湿地土壤P,K全量,速效果的剖面分布特征也不同,名层土壤全K含量均高于全P含量,植物,土壤和地表积水中P,K含量均有明的季节动态变化,一元非线性回归模拟均得到较理想的模拟模型,相关系数大多在0．9以上,F检验较显著。     

鼎湖山黄果厚壳桂、鼎湖钓樟群落主要营养元素的分配和生物循环

较系统地研究了鼎湖山黄果厚壳桂(Cryptocaryaconcinna)-鼎湖钓樟(Linderachunii)群落植物主要营养元素(P、K、Ca、Mg)的分配和生物循环特征。营养元素含量随群落层次、组分(器官)和元素不同而异。群落植物营养元素贮量为(kghm-2):P61.253,K928.764,Ca1212.771和Mg79.349。各元素贮量在不同层次中的大小分布序列为:乔木(94.3%-97.8%)>藤本(1.3%-4.1%)>灌木(0.8%-1.4%)>草本(0.05%-0.15%)。在乔木层,元素贮量则主要分布在树干和树枝两组分(38.6%-61.7%)。各元素在植物组分中的贮量序列为:Ca>K>Mg>P(根、干和皮)和K>Ca>Mg>P(其余器官)。群落植物营养元素年积累量为(kghm-2):P2.677,K41.550,Ca63.309和Mg3.693,其在群落植物中的分配格局与贮量的相类似。群落植物营养元素利用系数为:P0.18,K0.11,Ca0.09和Mg0.28;循环系数:P0.76,K0.61,Ca0.41和Mg0.84;周转期(a):P7.36,K15.12,Ca28.05和Mg4.30。     

上海金泽水库典型挺水植物碳、氮、磷化学计量特征的季节变化

为探究不同水生植物碳(C)、氮(N)、磷(P)含量及其化学计量比随季节的变化特征,本研究以上海金泽水库库区四种典型挺水植物旱伞草(Cyperus alternifolius),芦苇(Phragmites australis),千屈菜(Lythrum salicaria),水葱(Scirpus validus)为例,开展了季节性取样及室内分析,结果显示:(1)四种植物碳氮磷含量的变化规律不同。其中,对于植物碳含量,旱伞草和芦苇均无显著差异,千屈菜和水葱仅在冬季显著降低。对于植物氮含量,除旱伞草外,其他植物均在春季生长初期显著降低,在夏季生长旺盛时期显著升高,而旱伞草四季无显著差异。对于植物磷含量,水葱在四季均无显著差异,芦苇和千屈菜在冬季植物休眠期显著降低,旱伞草和芦苇磷含量在夏季显著降低。(2)四种植物C/N/P的季节性变化特征不同。其中,旱伞草C/N四季间无显著差异,其他3种植物C/N在春季生长初期显著升高;在C/P方面,水葱四季间无显著差异,芦苇和千屈菜在春季显著降低,旱伞草和芦苇C/P在夏季显著升高;常绿植物旱伞草N/P在四季无显著差异,其他3种植物N/P均在冬季生物量低时显著升高,春季N/P显著降低,而夏季生物量增长时N/P显著升高。(3)季节变化对四种植物C、P、N/P的影响远大于物种差异的影响,而植物N、C/N、C/P受物种差异的影响程度略大于季节变化。(4)四种植物C/N和C/P分别与N和P呈显著负相关,表明植物C/N和C/P分别受N和P主导;植物C与N、P二者在夏、秋季均无显著相关性,表明起支撑作用的C元素在夏、秋季独立于起生化作用的N、P元素;而营养元素N、P二者含量仅在植物生长的春、夏季显著相关。综上所述,不同植物碳氮磷含量及其化学计量比的季节变化特征不尽相同。今后的研究,可结合相关的生境因子,更好地探究其变化的内在机理。     

Cadmium,cobalt, chromium,and experimental myocardial infarction

In the case of experimental heart muscle infarction, the infarcted tissue of 18 pigs had a cadmium content of 0.38 μg/g dry weight and a cobalt content of 0.45 μg/g dry weight. In 25 non-infarcted pig hearts, the cadmium concentration amounted to 0.27 μg/g dry weight and the cobalt concentration to 0.37 μg/g dry weight. Thus, as far as the infarcted heart muscle tissue is concerned, there is a highly significant increase in the cadmium content (p<0.01) and a significant increase in cobalt content (p<0.05) compared to a non-infarcted heart. No differences were established with regard to chromium concentrations.     

Thermodynamics,the structure of integral membrane proteins,and transport

Membranes are structures whose lipid and protein components are at, or close to, equilibrium in the plane of the membrane, but are not at equilibrium across the membrane. The thermodynamic tendency of ionic and highly polar molecules to be in contact with water rather than with nonpolar media (hydrophilic interactions) is important in determining these equilibrium and nonequilibrium states. In this paper, we speculate about the structures and orientations of integral proteins in a membrane, and about how the equilibrium and nonequilibrium features of such structures and orientations might be influenced by the special mechanisms of biosynthesis, processing, and membrane insertion of these proteins. The relevance of these speculations to the mechanisms of the translocation event in membrane transport is discussed, and specific protein models of transport that have been proposed are analyzed.     

脱氮除硫菌株的分离鉴定和功能确认

从长期稳定运行的脱氮除硫反应器污泥中,分离获得两株具有脱氮除硫功能的芽孢杆菌。经形态观察、生理试验和16SrDNA序列比对,将两菌株归入芽孢杆菌属,菌株CB归类于Bacillus pseudofirmus,菌株CS则与Bacillus hemicellulosilytus和Bacillus halodurans最为接近。以Biolog板检测,菌株CB的基质多样性不明显,菌株CS则可利用Biolog板中多种碳源。菌株CB和菌株CS都能以硝酸盐氧化硫化物,其中菌株CB对硝酸盐、硫化物的转化能力大于CS,菌株CB对硝酸盐的亲和力也大于菌株CS。     

Sex determination,longevity, and the birth and death of reptilian species

Vertebrate sex‐determining mechanisms (SDMs) are triggered by the genotype (GSD), by temperature (TSD), or occasionally, by both. The causes and consequences of SDM diversity remain enigmatic. Theory predicts SDM effects on species diversification, and life‐span effects on SDM evolutionary turnover. Yet, evidence is conflicting in clades with labile SDMs, such as reptiles. Here, we investigate whether SDM is associated with diversification in turtles and lizards, and whether alterative factors, such as lifespan's effect on transition rates, could explain the relative prevalence of SDMs in turtles and lizards (including and excluding snakes). We assembled a comprehensive dataset of SDM states for squamates and turtles and leveraged large phylogenies for these two groups. We found no evidence that SDMs affect turtle, squamate, or lizard diversification. However, SDM transition rates differ between groups. In lizards TSD‐to‐GSD surpass GSD‐to‐TSD transitions, explaining the predominance of GSD lizards in nature. SDM transitions are fewer in turtles and the rates are similar to each other (TSD‐to‐GSD equals GSD‐to‐TSD), which, coupled with TSD ancestry, could explain TSD's predominance in turtles. These contrasting patterns can be explained by differences in life history. Namely, our data support the notion that in general, shorter lizard lifespan renders TSD detrimental favoring GSD evolution in squamates, whereas turtle longevity permits TSD retention. Thus, based on the macro‐evolutionary evidence we uncovered, we hypothesize that turtles and lizards followed different evolutionary trajectories with respect to SDM, likely mediated by differences in lifespan. Combined, our findings revealed a complex evolutionary interplay between SDMs and life histories that warrants further research that should make use of expanded datasets on unexamined taxa to enable more conclusive analyses.     

Automatic preparation,calibration, and simulation of deformable objects

Many simulation environments – particularly those intended for medical simulation – require solid objects to deform at interactive rates, with deformation properties that correspond to real materials. Furthermore, new objects may be created frequently (for example, each time a new patient's data is processed), prohibiting manual intervention in the model preparation process. This paper provides a pipeline for rapid preparation of deformable objects with no manual intervention, specifically focusing on mesh generation (preparing solid meshes from surface models), automated calibration of models to finite element reference analyses (including a novel approach to reducing the complexity of calibrating nonhomogeneous objects), and automated skinning of meshes for interactive simulation.     

The Biology of Arctic Charr, Salvelinus Alpinus, of Gander Lake, A Large, Deep, Oligotrophic Lake in Newfoundland, Canada

Resident Arctic charr, Salvelinus alpinus, are widespread throughout the island of Newfoundland. This study examines aspects of the biology and spatial and temporal distributions of the charr of Gander Lake, the third largest in Newfoundland (surface area = 11320ha, maximum depth = 288m, mean depth = 105.4m). The deepest part of the lake is approximately 258m below sea level. The lake is well oxygenated from the surface to the bottom during all seasons. Sampling was conducted with Lundgren multiple-mesh experimental gillnets and baited hooks. There appears to be two morphs present, based on colour (dark and pale) and certain meristic characteristics. Dark charr were caught mainly in benthic nets (at depths from 1 to 100m inclusive) with only a few pelagic captures. Pale charr were caught only in benthic nets at depths between 20 and 100m inclusive. The maximum depth sampled was 196m, but there was no catch. There was a tendency for dark charr to be found in deeper, cooler water as the upper water column and inshore areas warmed during summer. There was no apparent trend in size of charr with depth sampled. Dark and pale charr both fed on benthic macroinvertebrates; sticklebacks were consumed only by dark charr and the importance of this prey item increased with size of predator. Zooplankton and surface food were not utilised by Gander Lake charr. Results of the study are compared with findings reported for other water bodies in Newfoundland and Labrador, North America, and Europe, particularly Loch Ness which has similarities in morphometry and trophic status to Gander Lake.     

Cadmium,copper, and zinc levels in the rice and rice field soil of Houston,Texas

Fifty-one pairs of hulled rice samples and the soil from which each rice sample was grown were analyzed for heavy metals in August, 1979, in order to estimate the background contamination of cadmium (Cd), copper (Cu), and zinc (Zn) in rice grown in the Houston, Texas area. Both samples were divided into three groups by soil types and colors. The cadmium concentration in Texas rice was only one-half to one-quarter lower than that of Asian rice. However, the levels of Cu and Zn in rice in Texas were similar to those reported. Soil heavy metals were lower than ever reported, but these values were consistent with the geochemical characteristics of the Texas Houston area. No particular relationship was found between the three metals in rice and the metals in soil where the sampled rice was grown.     

Magnesium,calcium, copper,and zinc in meals

Meals of 12 diets were prepared from conventional foods with precautions against contamination by metallic elements because of epidemiologic associations between ischemic heart disease and the metabolism of magnesium, calcium, copper, and zinc. Magnesium, calcium, copper, and zinc were measured by atomic absorption spectrometry with satisfactory accuracy and precision. The mean daily amount of copper in the diets was less than the apparent adult requirement. Mean amounts of magnesium and zinc were close to apparent requirements; however, adults consuming amounts less than one standard deviation below these means may be depleting body stores and be at risk of pathology. Magnesium and copper were highly correlated (r=0.849,P=0.0001) in meals. This and other significant correlations probably will prevent the relationships of these elements to ischemic heart disease from being elucidated by epidemiology. Metabolic experiments will be necessary to differentiate among several hypotheses.     

Erythrocyte Indices, Microminerals and Ratios, Antioxidants and Lipids in Centrum Materna Diet-Supplemented Omani Mothers

Venous (maternal) and cord blood (neonatal) samples of Omani women who had a daily supplement of Centrum Materna multivitamin and multimineral tablet throughout pregnancy were investigated at late preterm (n=37) and at term (n=37) delivery for erythrocyte indices, micromineral, antioxidant, and lipid values. Hemoglobin (Hb), hematocrit (HCT), mean cell volume (MCV), red cell distribution width (RDW), copper (Cu), zinc (Zn), ceruloplasmin, erythrocyte Cu-Zn superoxide dismutase (Cu-Zn SOD), cholesterol, apolipoprotein (apo) A-I and apo B were measured by appropriate analytical systems. Cu/zinc and Cu/ceruloplasmin ratios were calculated. The erythrocyte indices were normal in neonatal blood but showed borderline anemia in maternal blood of both groups. There were significantly decreased values of Cu (P=0.012), Zn (P=0.001), apo A-I (P=0.029), and Cu/ceruloplasmin ratio (P=0.032) in late preterm compared to term mothers. Significantly decreased values of Cu (P=0.003), ceruloplasmin (P<0.0001), apo A-I (P=0.024), and Cu/Zn ratio (P=007) were observed in late preterm relative to term neonates. Late preterm mothers were significantly younger (P=0.027) than term mothers. Maternal age correlated positively with apo A-I (r=0.424, P=0.012) and negatively with Cu/Zn ratio (r=-0.353, P=0.040). The findings suggest that with daily dietary Centrum Materna supplementation throughout pregnancy, hematological indices were maintained within normal in mothers and neonates, but the levels of microminerals and micromineral ratios were subnormal in late preterm mothers and their neonates.