Measuring the Surface Roughness of Stream Stones

Measuring the fine-scale heterogeneity of stones and other substrates is a challenge for benthic ecologists. I describe a method for measuring the roughness of stones that is based on the ratio of two surface area measurements: one that follows substrate contours and one based on a similar-sized modified spheroid. This roughness index is easily measured, assesses the entire surface of stones, and enables the measurement of replicate stones. Roughness measurements of 14 rock types demonstrated that values obtained were consistent with perceived roughness and porosity. Application of the roughness index to a published data set produced a curvilinear relationship between stone roughness and the biomass of algae in roughness-associated crevices.     

Diel changes in stream benthos density on stones and artificial substrates

Diel changes in stream benthos density were studied by comparing faunal densities on naturally occurring stones collected at noon and at midnight and on artificial substrates (bricks) collected at 2 hr intervals for 24 hr. Over all dates and all rivers, on stones, nighttime densities were higher in 37 cases, lower in 35 cases and unchanged in three cases. The magnitude of nocturnal density increases (expressed as a proportion of daytime density) ranged between 0.03 and 1.08 and the magnitude of nocturnal density decreases ranged between 0.01 and 0.81. Diel density changes on bricks generally were variable and not synchronized with changes in light intensity, but in most cases (60%) densities were greater at night.A new, accurate and rapid method to estimate the area of stone surface is also described.     

A quick method of determining rock surface area for quantification of the invertebrate community

Stone and rock substrates provide important habitat for many types of stream-dwelling invertebrates. Measures of the invertebrate communities inhabiting rock substrates are often an important component of ecological, monitoring and disturbance studies in streams. A major obstacle to researchers examining rock-inhabiting invertebrates is the time and effort expended on currently used methods of determining rock surface area to derive invertebrate densities on these substrates. In an attempt to more efficiently determine invertebrate densities from rock substrates in streams, we tested a direct method of calculating rock surface area from rock weight or displacement volume. This method allows very quick determinations of rock surface area in the field. Surface area estimates made using this technique were highly correlated to those from a widely used and more time-consuming method. Measurements made using this new method should theoretically give better surface area estimates than any other commonly used technique.     

Macroinvertebrate community in the lower Ebro river (NE Spain)

We examine the macroinvertebrate community composition and dynamics in the last 60 km of the Ebro river (NE Spain). Different sampling methods (individual stones, Surber, kick samplers and artificial substrate) were used depending on the characteristics of the sites chosen (substrate, current velocity, saline influence).The high nutrient content and the abundance of UFPOM is the origin of a high density in stones although no clear pattern exists between stone surface area and density or species richness. The high spatial heterogeneity and moderate disturbance intensity and frequency because of river regulation explains the relatively rich macroinvertebrate community and the low temporal changes in the community.     

Measurement of surface area of stones

The surface area of stones can be quickly, accurately, and precisely estimated from linear regression equations of area on a two-dimensional term of the form (xy + yz + zx) where x, y, and z are either the axial dimensions or the axial perimeters of stones. Dimension measurements are made with calipers, and perimeters are measured with a tape measure or a mapping wheel. The best fit slopes for the equations are determined from a representative sample of stones whose surface areas are measured by mapping. Estimates of surface areas of river-worn cobbles by these methods had mean percentage absolute errors of about 4%, considerably better than other methods examined.     

Metabolism in marine flatfish--III. Measurement of elastase activity in the digestive tract of Dover sole (Solea solea L.)

A critical assessment of different methods for measuring elastase activity in crude preparations has been made using whole intestinal homogenates of Dover sole. The use of the natural substrate elastin or its dyed derivatives gave optimal pH values in the alkaline region (pH 9.4-9.8) whereas artificial substrates showed optimal hydrolysis nearer neutrality in the region pH 8.1-8.2. Exoproteases may interfere with certain assay procedures. The properties of Dover sole elastase have been further investigated using chromatographic techniques which indicated that the main elastase activity has a molecular weight of approximately 19,500 and an isoelectric point in the region of pH 5.7.     

A critical examination of four methods of estimating the surface area of stone substrate from streams in relation to sampling Simuliidae (Diptera)

Four methods of calculating stone surface area are examined for their value in estimating simuliid larval density. All methods produced area estimates highly correlated with each other. Stone surface area poorly correlated with simuliid abundance, which we concluded was the result of a highly variable microhabitat and the inability to estimate the surface area actually occupied by larvae. Therefore, if an estimate of stone surface area is required, the simplest methods are sufficient (e.g., maximum length × 90° maximum width).     

Sampling harmful benthic dinoflagellates: Comparison of artificial and natural substrate methods

This study compared two collection methods for Gambierdiscus and other benthic harmful algal bloom (BHAB) dinoflagellates, an artificial substrate method and the traditional macrophyte substrate method. Specifically, we report the results of a series of field experiments in tropical environments designed to address the correlation of benthic dinoflagellate abundance on artificial substrate and those on adjacent macrophytes. The data indicated abundance of BHAB dinoflagellates associated with new, artificial substrate was directly related to the overall abundance of BHAB cells on macrophytes in the surrounding environment. There was no difference in sample variability among the natural and artificial substrates. BHAB dinoflagellate abundance on artificial substrates reached equilibrium with the surrounding population within 24 h. Calculating cell abundance normalized to surface area of artificial substrate, rather than to the wet weight of macrophytes, eliminates complications related to the mass of different macrophyte species, problems of macrophyte preference by BHAB dinoflagellates and allows data to be compared across studies. The protocols outlined in this study are the first steps to a standardized sampling method for BHAB dinoflagellates that can support a cell-based monitoring program for ciguatera fish poisoning. While this study is primarily concerned with the ciguatera-associated genus Gambierdiscus, we also include data on the abundance of benthic Prorocentrum and Ostreopsis cells.     

An AFM determination of the effects on surface roughness caused by cleaning of fused silica and glass substrates in the process of optical biosensor preparation

The covalent attachment of organic films and of biological molecules to fused silica and glass substrates is important for many applications. For applications such as biosensor development, it is desired that the immobilised molecules be assembled in a uniform layer on the surface so as to provide for reproducibility and speed of surface interactions. For optimal derivatisation the surface must be appropriately cleaned to remove contamination, to create surface attachment sites such as hydroxyl groups, and to control surface roughness. The irregularity of the surface can be significant in defining the integrity and density of immobilised films. Numerous cleaning methods exist for fused silica and glass substrates and these include gas plasmas, and combinations of acids, bases and organic solvents that are allowed to react at varying temperatures. For many years, we have used a well established method based on a combination of washing with basic peroxide followed by acidic peroxide to clean and hydroxylate the surface of fused silica and glass substrates before oligonucleotide immobilisation. Atomic force microscopy (AFM) has been used to evaluate the effect of cleaning on surface roughness for various fused silica and glass samples. The results indicate that surface roughness remains substantial after use of this common cleaning routine, and can provide a surface area that is more than 10% but less than 30% larger than anticipated from geometric considerations of a planar surface.     

Discoidals and Problematical Stones from Mississippian Sites in Minnesota

Abstract

There is no conclusive evidence that discoidals, chunkey stones or similar problematical stones were used exclusively or intermittently for games, ceremonials, food preparation or other village purposes, but the weight of evidence from eyewitness accounts suggests the dominance of game use. There are several eyewitness records of the game as olaved by the tribes of the Southeast and by some Siouan tribes of the plains and the Missouri Valley. Discoidals are found most frequently at late prehistoric Mississippian sites.

Recent Minnesota finds include: a single artifact with unusual features (Fig. 1), identified tentatively as a chunkey game piece, recovered by the author in 1976 from the Bryan site; a broken, more conventional game stone discovered at the neighboring site of Silvernale in 1975 (Harrison, 1978); a surface find at the Bartron site in 1978 by John Barnett; and an artifact, either a chunkey stone or a grinding stone, also found by John Barnett near the entrance of Belle Creek into the Cannon River. All of these sites are in the Red Wing area and these recent finds, together with other known discoidals from Goodhue County, link the Mississippian villages of the Red Wing area to the chunkey playing region further south.     

Habitat and shelter requirements of the stone crayfish,Austropotamobius torrentium Schrank

The attractiveness of shelters and the relationship between crayfish size and refuge size were investigated in the stone crayfish Austropotamobius torrentium. Shelter suitability was mainly determined by water velocity, stone surface area and stone width. Water depth and stone height had no influence on crayfish occupancy of stones. Austropotamobius torrentium avoided shelters in areas of water velocities exceeding 25 cm s^–1. They preferred large stones with a bearing surface greater than 300 cm². The probability of crayfish occupation rose quickly as stones' bearing surface increased up to 900 cm². Crayfish were exclusively caught underneath stones at least 3.19 times longer and 1.25 times wider than the carapace length of the refuge occupant. Large males occupied larger stones, where no relationship was detected between female size and stone refuge size.     

A technique for assessing the composition and density of the macroinvertebrate fauna of large stones in streams

A device for quantitatively sampling the macroinvertebrates of large stones in streams is described. In comparison to the usual method for sampling the fauna of large stones, (the lifting of stones upstream of a hand net), the present method accurately samples stonedwelling animals that are good swimmers. Details are given of a reliable method to measure the surface area of stream stones using thin plastic sheeting.     

大批量测定植物(互花米草)叶面积的一种新方法

叶面积的准确测定是评价生态系统能流、碳流和水分利用的重要基础.目前常用的叶面积测定方法都有其局限性,有些方法快捷、准确,但仅适用于小批量测定;大多数方法很难在较短时间内准确进行大批量测定.本文以互花米草叶面积测定为例,探讨了以扫描仪和叶片干重为基础,结合PHOTOSHOP图像处理技术,大批量、快捷、准确测定植物叶面积的方法--扫描-干重法.结果表明:虚拟正方形叶片边长与叶子像素成幂函数曲线关系,公式为419.85x^1.9693,R≈1.00;用此公式验证扫描-干重法,相对误差仅为3.651%.用扫描-干重法测得的结果与方格法相比无显著差异(P=0.473),表明该方法是可行的.     

An inexpensive,accurate method for measuring leaf area and defoliation through digital image analysis

We report a protocol using a common desk-top scanner and public domain software for measuring existing leaf area and leaf area removed as a result of herbivory. We compared the accuracy and precision of this method to that of a standard leaf area meter. Both methods were used to measure metal disks of a known area, the area of soybean (Glycine max L.) leaves, and the area removed by simulating leaf feeding with a hole-punch. We varied the amount of injury across a low, medium, and high degree of simulated feeding. The mean area of 10 cm2 and 50 cm2 metal disks was more accurately estimated with the leaf area meter than the desk-top scanner. Leaf area estimates from both methods were highly correlated. The desk-top scanner accurately estimated the leaf area removed from the low, medium, or high degree of simulated leaf feeding. However, the leaf area meter overestimated low levels of simulated feeding injury. Though measuring a leaf's surface area with a desk-top scanner requires two steps (creating a digital image file and calculating the area represented by that image), the overall time required to measure leaf injury is shorter than with a leaf area meter. This relatively simple and inexpensive method of estimating leaf area and feeding damage has advantages in certain experimental situations where a prefeeding measurement of the leaf is impossible or undesirable, or when small amounts of feeding occur.     

Microform bed clusters: are they preferred habitats for invertebrates in a flood‐prone stream?

SUMMARY 1. Microform bed clusters are bedform microunits in streams. They consist of an obstacle clast (a large surface stone) against which other stones are stacked in a specific manner. Stream ecologists have suggested that these clusters are better flood refugia and more valuable habitats for invertebrates than single surface stones because of their higher stability during high‐flow events and their greater diversity of microhabitats available for colonisation. 2. To test these predictions in the Schmiedlaine, a flood‐prone prealpine stream, we sampled invertebrates on clustered and single stones on a total of seven occasions including before and after a moderate spate, two major floods and a minor spate. We also monitored surface particle stability during the second major flood and the minor spate. 3. Before the second flood (return period 1–2 years), we determined the exact positions of 60 clusters (60 obstacle clasts with 136 associated smaller particles) and 50 single stones in a 250‐m reach. We sampled the fauna on stones in the clusters, on well‐embedded single stones, and on loose single stones. Only six obstacle clasts and one single stone remained after the flood, implying movement of almost the entire surface layer. Therefore, we sampled the invertebrates on stones in newly formed clusters, on well‐embedded and single loose stones 3 and 11 days after the flood. The minor spate, in contrast to the second flood, moved only one of 495 monitored surface particles. 4. Three days after the flood, invertebrate density on clustered stones and both single stone categories were similar and equalled 34% of the mean pre‐flood density. Eight days later, density had almost doubled. The relatively high survival and rapid recovery suggest that invertebrates found refugia during the flood. However, the very low stability of clusters and single stones implied that surface particles were unimportant as refugia. 5. Total invertebrate density and taxon richness were never higher on clustered than on single stones (regardless of the timing of sampling relative to the last previous high‐flow event). Densities of the seven most common taxa and invertebrate community structure were also generally similar between particle types. We conclude that microform bed clusters cannot be regarded as more valuable invertebrate habitats than single surface stones in the Schmiedlaine.     

SPECIALTY CONFERENCE: The Treatment of Retained Gallstones

Various techniques are available to evaluate patients suspected of having common duct stones before an operation on the biliary tract. In patients without jaundice, intravenous cholangiography with tomography may provide satisfactory visualization of the biliary system and its contents. Sonography and computerized axial tomography are useful noninvasive methods. Endoscopic retrograde and transhepatic cholangiography are invasive techniques; but, when successful, they provide the most precise preoperative information obtainable about the presence or absence of stones in the biliary system. The most appropriate diagnostic procedures must be carefully selected for each patient. Each year in 3,000 to 4,000 cases, stones are found remaining in the bile ducts after common duct exploration for the removal of stones. Retained stones can be treated by nonoperative extraction, by irrigation techniques and by surgical removal. Extraction methods probably deserve first consideration, if experienced personnel are available. The technique of irrigation of the common bile duct with cholic acid or other solutions, although limited in success, may also be tried; if these procedures fail, then reoperation is indicated.     

A precise and non-destructive method to calculate the surface area in living scleractinian corals using X-ray computed tomography and 3D modeling

The surface area of corals represents a major reference parameter for the standardization of flux rates, for coral growth investigations, and for investigations of coral metabolism. The methods currently used to determine the surface area of corals are rather approximate approaches lacking accuracy, or are invasive and often destructive methods that are inapplicable for experiments involving living corals. This study introduces a novel precise and non-destructive technique to quantify surface area in living coral colonies by applying computed tomography (CT) and subsequent 3D reconstruction. Living coral colonies of different taxa were scanned by conventional medical CT either in air or in sea water. Resulting data volumes were processed by 3D modeling software providing realistic 3D coral skeleton surface reconstructions, thus enabling surface area measurements. Comparisons of CT datasets obtained from calibration bodies and coral colonies proved the accuracy of the surface area determination. Surface area quantifications derived from two different surface rendering techniques applied for scanning living coral colonies showed congruent results (mean deviation ranging from 1.32 to 2.03%). The validity of surface area measurement was verified by repeated measurements of the same coral colonies by three test persons. No significant differences between all test persons in all coral genera and in both surface rendering techniques were found (independent sample t-test: all n.s.). Data analysis of a single coral colony required approximately 15 to 30 min for a trained user using the isosurface technique regardless of the complexity and growth form of the latter, rendering the method presented in this study as a time-saving and accurate method to quantify surface areas in both living coral colonies and bare coral skeletons. Communicated by Biology Editor Dr Michael Lesser     

不同因子驱动下通过不同途径发生的红树林斑块数量和面积变化量的计量方法

为深入阐明区域红树林空间演变机理,需对红树林斑块数量和面积在不同因子驱动下通过不同途径发生的变化量进行准确计量。提出了在GIS平台支持下的通过空间叠置分析方法进行斑块数量和面积变化量计量的两种方法——精确计量法和整体计量法。首先将前后两期通过遥感图像提取的红树林斑块分布图、遥感图像进行叠合,采用视觉信息叠合方法,将全部斑块划分为众多具有相同主要驱动因子和变化途径的分析单元;若前后期遥感图像能够精确配准,采用精确计量法计量:通过线与多边形叠置方法,用前期斑块的线状图对后斑块的面状图、后期斑块的线状图对前斑块的面状图分别进行切割,每个分析单元得到多个亚斑块,逐一确定每个亚斑块的驱动因子、变化途径,据此统计每个分析单元中斑块数量和面积在不同因子驱动下通过不同途径发生的变化量;若前后期遥感图像难以精确配准,采用整体计量法计量:对于每个分析单元,根据斑块恢复的难易程度、面积和斑块数量变化量的大小,确定其主要驱动因子和主要变化途径,该分析单元前、后期斑块数量和面积之差即为其在监测期间由该因子驱动通过该途径发生的斑块数量和面积变化量。尽管整体计量法对红树林空间演变机制分析的结果与精确计量法存在一定差异,但也属于定量分析范畴,都能深刻阐明红树林空间演变机制,能够全面、准确地反映了区域红树林斑块数量和面积在监测期内增加、减少的动态过程。     

石质文物微生物检测技术的研究进展

本论文针对国内外最新的石质文物微生物的检测技术进行了论述,主要包括核酸分析鉴定方法、细胞膜分析法、次级代谢产物分析法和传统培养法等。并综合比较各种方法的优势和不足,对石质文物的生物保护提出展望。石质文物微生物的无损或微损快速检测技术的建立,对于进一步清理石质文物的微生物污染,有效防治微生物对石质文物的腐蚀,保护我国宝贵的文化遗产具有重要的意义。     

肝外胆管结石微创治疗的研究进展

肝外胆管结石是肝胆外科临床常见病,严重威胁患者健康。目前该病治疗主要以手术治疗为主,以往的手术方式主要以剖腹胆总管切开取石为主,但创伤较大,恢复较慢,后遗症较多。随着微创技术的发展,腹腔镜、胆道镜及十二指肠镜等微创治疗技术以其创伤小、恢复快等优势越来越多的被肝外胆管结石患者采用。微创治疗肝外胆管结石的方法也日趋多样化,如经消化内镜治疗,经腹腔镜治疗,腹腔镜联合消化内镜治疗及腹腔镜、胆道镜、十二指肠镜三镜联合治疗等。本文就肝外胆管结石治疗中各种微创技术的研究进展做一综述。