活体肺部组织的三维重建及其临床意义

活体肺部组织的三维重建对医学解剖和临床有重要的意义。本文针对活体肺器官三维重建存在的困难，在图象预处理和重建方法上，采用了一系列新颖的技术，首次得到了能进行剖割，旋转，透明和彩色明暗化的肺部及其内部管道的三维显示。临床评价说明，重建结果是有意义的．     

Plant macroscopic remains from recent sediments of Banks Island,Northwest Territories,and Bathurst Island,Nunavut, Canada,and the interpretation of Quaternary cold stage plant macroscopic assemblages

Macroscopic plant remains were extracted from recent sediments of streams on Banks Island and Bathurst Island. Analyses of the samples are given and their general relation to the vegetation is described. Problems of interpretation of the contemporary and Quaternary cold stage macroscopic assemblages include the variation of the representation of taxa, the significance of taphonomy, especially under fluvial conditions, and the origin of the assemblages in a mosaic of vegetation. The contribution of analyses of macroscopic remains to interpretations of vegetation and environment based on pollen analysis is emphasised. Copyright © 2000 John Wiley & Sons, Ltd.     

Sources of organic matter in surface sediments of the Louisiana Continental margin: Effects of major depositional/transport pathways and Hurricane Ivan

Lignin and pigment biomarkers were analyzed in surface sediments of the Louisiana Continental margin (LCM) to distinguish differences in the degradative state of sedimentary organic matter along and between two major depositional pathways (along shore and offshore to the Mississippi Canyon) from Southwest (SW) Pass in July 2003. Barataria Bay, an inter-distributary estuary, was also assessed as a potential source of terrestrial organic matter to the LCM. Sediment signatures taken along the same pathways after Hurricane Ivan (October 2004) were compared with the pre-Ivan signature to elucidate carbon dynamics after major hurricane events. Density fractions were investigated at key stages across the LCM. Mississippi Canyon sediments are a depocenter for labile and refractory organic matter derived from river and previously deposited shelf sediments. Barataria Bay material may be a contributing source of sedimentary organic matter in shallow shelf areas bordering the bay and is thus potentially important in carbon cycling in sediments of these shallow areas; however, our results show that organic matter inputs from the bay were likely rapidly decomposed and/or diluted. Hurricane Ivan mobilized sedimentary organic carbon (SOC) offshore and homogenized terrestrial sediment parameters and gradients. As observed through pigment concentrations sediments tended to equilibrate to a more steady-state condition within months of the disturbance. Insights from density fractions show that selective degradation and aggregation/flocculation processes were also very important processes during cross-shelf transport. Zooplankton grazing, largely on diatoms and other algae, was a shelf wide phenomenon, however, grazing products dominated the marine-derived SOC in margin sediments west of the birdsfoot delta indicated by the abundance of steryl chlorin esters (SCEs).     

Pliocene flora and paleoenvironment of Zanda Basin,Tibet, China

This paper describes a plant megafossil assemblage from the Pliocene strata of Xiangzi, Zanda Basin in the western Qinghai-Tibet Plateau. Twenty-one species belonging to 12 genera and 10 families were identified. Studies show that the Pliocene vegetation in Zanda Basin was mostly deciduous shrub composed of Cotoneaster, Spiraea, Caragana, Hippophae,Rhododendron, Potentilla fruticosa, etc. Leaf sizes of these taxa were generally small. Paleoclimate reconstruction using Coexistence Analysis and CLAMP showed that this area had higher temperature and precipitation in the Pliocene than today, and distinct seasonal precipitation variability was established. The reconstructed paleoelevation of Zanda Basin in the Pliocene was similar to modern times. In the context of central Asian aridification, the gradual drought in the area beginning in the late Cenozoic caused vegetation to transition from shrub to desert, and the flora composition also changed.     

Long-term perspective on the relationship between phytoplankton and nutrient concentrations in a southeastern Australian estuary

Sixteen years (1997–2013) of physicochemical, nutrient and phytoplankton biomass (Chlorophyll-a (Chl-a)) data and a decade (2003-2013) of phytoplankton composition and abundance data were analyzed to assess how the algal community in a temperate southeastern Australian estuary has responded to decreased chronic point source nitrogen loading following effluent treatment upgrade works in 2003. Nitrogen concentrations were significantly lower (P < 0.05) following enhanced effluent treatment and Chl-a levels decreased (P < 0.05) during the warmer months. Temperature and nutrient concentrations significantly influenced temporal changes of Chl-a (explaining 55% of variability), while salinity, temperature, pH and nutrient concentrations influenced phytoplankton abundance and composition (25% explained). Harmful Algal Bloom (HAB) dynamics differed between sites likely influenced by physical attributes of the estuary. This study demonstrates that enhanced effluent treatment can significantly decrease chronic point source nitrogen loading and that Chl-a concentrations can be lowered during the warmer months when the risk of blooms and HABs is greatest.     

Hydrocarbon micro-seepage detection from airborne hyper-spectral images by plant stress spectra based on the PROSPECT model

Hydrocarbon micro-seepage can result in vegetation spectral anomalies. Early detection of spectral anomalies in plants stressed by hydrocarbon micro-seepage could help reveal oil and gas resources. In this study, the origin of plant spectral anomalies affected by hydrocarbon micro-seepage was measured using indoor simulation experiments. We analyzed wheat samples grown in a simulated hydrocarbon micro-seepage environment in a laboratory setting. The leaf mesophyll structure (N) values of plants in oil and gas micro-seepage regions were measured according to the content of measured biochemical parameters and spectra simulated by PROSPECT, a model for extracting hydrocarbon micro-seepage information from hyper-spectral images based on plant stress spectra. Spectral reflectance was simulated with N, chlorophyll content (C_ab), water content (C_w) and dry matter content (C_m). Multivariate regression equations were established using varying gasoline volume as the dependent variable and spectral feature parameters exhibiting a high rate of change as the independent variables. We derived a regression equation with the highest correlation coefficient and applied it to airborne hyper-spectral data (CASI/SASI) in Qingyang Oilfield, where extracted information regarding hydrocarbon micro-seepage was matched with known oil-producing wells.     

油蒿群落植物多样性动态

油蒿为鄂尔多斯高原植被的优势种和建群种,油蒿群落的植物多样性有向顶极阶段增加的趋势。植物多样性的季节变化与气候的季节变化密切相关。人类活动特别是过度放牧,引起油蒿群落的退化,导致植物多样性降低。围育可使退化的油蒿群落向正向演替进行,使群落的植物多样性提高。     

巢湖4种蚌类不同组织中5种微量元素含量及其空间变化

蚌类在湿地生态系统元素的富集与转化过程中发挥重要作用.以巢湖常见扭蚌（Arconaia lanceolata）、三角帆蚌（Hyriopsis cumingii）、褶纹冠蚌（Cristaria plicata）和圆顶珠蚌（Unio douglasiae）为对象,分析其内脏团、外套膜（包含鳃,下同）和斧足中5种微量元素（Cu、Zn、As、Cd、Pb）的含量.结果表明：5种元素在4种蚌体内均有检出,除Zn在圆顶珠蚌组织间表现为外套膜>内脏团>斧足外,4种蚌体组织间5种微量元素含量均表现为内脏团 > 外套膜 > 斧足;4种蚌类各微量元素平均含量均表现为Zn > Cu > As > Pb > Cd;Cu和Pb在4种蚌类中的平均含量表现为扭蚌 > 褶纹冠蚌 > 圆顶珠蚌 > 三角帆蚌,扭蚌各组织中Pb含量是其他3种蚌类的2.62~6.99倍,Zn的各平均含量表现为圆顶珠蚌 > 扭蚌 > 三角帆蚌 > 褶纹冠蚌,As表现为圆顶珠蚌 > 三角帆蚌 > 褶纹冠蚌 > 扭蚌,Cd表现为扭蚌 > 圆顶珠蚌 > 三角帆蚌 > 褶纹冠蚌,Cd在圆顶珠蚌和扭蚌中的含量是三角帆蚌和褶纹冠蚌的2.75~6.08倍.不同种类之间微量元素含量的差异大于同一种类微量元素含量的空间差异.微量元素污染较重的河口区蚌体组织具有较高的微量元素含量,污染较轻的河口中蚌体组织各微量元素含量也相对较低,表明蚌类可作为巢湖水体微量元素污染监测的指示生物.4种蚌类中Pb、Cd、As含量均未超出国家食品安全标准的限定值.     

Middle Westphalian plant fossils from the West Cumberland Coalfield,UK

Twenty-six form-species of plant macrofossils occur in the Coal Measures exposed in the Howgill Head Quarry, Whitehaven, Cumbria, UK. They belong to the Neuropteris semireticulata Subzone in the lower part of the Paripteris linguaefolia Zone, indicating the uppermost Duckmantian. They confirm that the sandstones exposed in this part of the West Cumberland Coalfield are part of the Whitehaven Sandstone Formation, and not a stratigraphically lower unit as previously suggested. The Howgill head fossils represent the only well documented example of a N. semireticulata Subzone assemblage in Britain, although comparable assemblages are known from coeval strata in northern France, Belgium, northern Germany and Poland.