共查询到20条相似文献,搜索用时 31 毫秒
1.
B. Kopp 《Biometrical journal. Biometrische Zeitschrift》1978,20(5):495-501
This is the first part of a survey of hierarchical clustering algorithms using joining methods: the Single-Linkage algorithm. Complete-Linkage and general algorithms defined by d(Ai, B) = = α,d(Ai, Ar)±αsd(Ai, As)±βd(Ar, As) will be discussed in two subsequent papers. 相似文献
2.
Christopher S. Campbell 《American journal of botany》1982,69(10):1625-1635
Eleven species of Andropogon produce single-stamened flowers, and all but one of these species bear some cleistogamous flowers. Nine of the species, all diploid perennials, make up the Andropogon virginicus complex. Cleistogamy in the virginicus complex results from precocious maturation of the flowers, which leaves them confined within their spikelets at anthesis. Variation in flowering mode (expressed as mean % chasmogamy) is correlated significantly (P < 0.01) with variation in peduncle length (rs = 0.67), spikelet length (rs = 0.49), and anther length (rs = 0.69). The strength of the correlation (r = 0.94) between pollen grain number per anther and anther length makes the latter a good measure of pollen-ovule ratios in the single-stamened flowers of this group. Taxa with the highest frequency of cleistogamous flowering are also the most successful colonizers of disturbed habitats. It is suggested that cleistogamy is important in the reproductive isolation of the numerous, closely related subspecific taxa of the virginicus complex. 相似文献
3.
Joseph Hitimana James Kiyiapi Joseph Njunge Rosemary Bargerei 《African Journal of Ecology》2010,48(3):699-708
Mount (Mt) Elgon forest in western Kenya is important for biodiversity, environmental protection and socio‐economic development. Characterizing forest conditions is essential for evaluation of sustainable management and conservation activities. This paper covers findings of a study which determined and analysed indicators useful in monitoring disturbance levels in the Mt Elgon Forest. A systematic survey was carried out and covered 305 plots of 0.02 ha and 250 smaller nested regeneration plots along 10 belt transects that were distributed in five blocks within the moist lower montane forest type. Collected and analysed data include types of disturbance, tree species composition, abundance and logged species. Correlation breakdown among disturbance types revealed that, paths were indicators of the number of tree harvesting sites (rs =1.00, P < 0.01) and of de‐vegetated areas through grass harvesting (rs = 0.90, P = 0.04). Solanum mauritianum Scop. was an indicator of old‐charcoal production sites. Logging targeted 13 tree species and harvested trees with diameter at breast height above 20 cm. The most exploited species were Olea capensis L. and Deinbolia kilimandscharica Taub. All exploited species had low regeneration but tree regeneration was not an effective indicator of logging. 相似文献
4.
Abstract 1 Two new concepts describing the origin of insects caught in an attractive trap are presented. 2 Male European pine sawflies Neodiprion sertifer Geoffroy (Hymenoptera: Diprionidae) were marked and released from 50, 100, 200, 400 and 800 m in the four cardinal directions around a centrally placed pheromone trap. 3 Based on linear regression of transformed data, we calculated the seasonal sampling range (rs) as 1040 m. 4 We estimated the previously defined ‘effective sampling area’ (α) at 4.9 ha, assuming that the insects are evenly distributed around the trap and that they are attracted from a circular area around it. This is the area from which all insects originate if the trap is 100% effective within the area but captures nothing outside of it. The effective sampling area reveals nothing about the origin of the insects caught. We defined the Cumulative Proportional Catch (CPC) that gives the proportion of the trap catch that originates from an area within a distance r from the trap. At r = rs CPC = 1, and in our study 50% of the captured insects originated up to 450 m from the trap. Thus, for the trap used in this study, a relatively large proportion of the catch originates some distance from the trap. 5 We also defined the Catch Concentration (CC), which is the ratio of the radius of the effective sampling area (rα) to rs. For our data, CC = 0.12, which is intermediate to high compared to the few other studies that we have extracted information from. If rα is considerably lower than rs, then only a small proportion of the insects caught originate from close proximity to the trap. When rα is close to rs, the catch adequately mirrors the population within most of its sampling range. 6 By using these two new concepts, we will better understand why monitoring traps mirror the local population in some cases but not in others. This will help in designing more reliable monitoring programmes. 相似文献
5.
U. Mühlenhardt-Siegel 《Helgoland Marine Research》1981,34(4):427-437
The macrofauna of a dumping area in the eastern part of the German Bight (North Sea) was investigated in July, August and November, 1978 at five stations situated on a transect including central and peripheral areas of the dumping region. Abundance and biomass (ash free dry weight) of the macrofauna and its variation from July to November were analysed as well as the biomass of different taxa. Molluscs dominated over polychaetes, crustaceans and echinoderms. A positive correlation seemed to exist between mud content and biomass at the peripherally situated stations. In the central sewage sludge area, however, the biomass values were reduced. In late autumn the biomass decreased in the entire area due to the death ofDiastylis rathkei, Abra alba andPectinaria koreni. These species were replaced by the molluscNucula turgida and polychaeteNephtys hombergii. In autumn the biomass values also showed a distinct minimum at the central stations. 相似文献
6.
Structural effects of bottom and surface water samples from two dumping grounds in the inner German Bight on the development of three meroplanktonic organisms(Pomatoceros triqueter: Polychaeta,Psammechinus miliaris: Echinodermata andCrassostrea gigas, Mollusca) were investigated. The titaniumdioxide dumping site was sampled immediately after dumping (within the visible waste trail 1 km behind the vessel), and 10 h after dumping. Samples were taken in the sewage sludge deposition area in the intervals between the usual dumping activities, regardless of the exact dumping schedule. The preserved bioassay test organisms were inspected microscopically to count percentages of normal larval hatch in test water samples, reference water samples and laboratory aged control water samples (5 to 10 replicates). The relative water quality at various dumping sites was expressed in terms of net risk-values (Woelke, 1972) compared to hatching rates observed in the controls. Larval development ofP. triqueter was significantly suppressed (up to –22 % net risk) in trail water of the titanium dioxide dump site while the development of sea urchin larvae was still affected in the 10 h surface samples. Hatching of all test organisms in bottom-water samples from the centre of the sewage sludge dump site was affected to different degrees when compared to reference areas about 4 km north or 6 km northwest of the dumping area. The general usefulness of standardized bioassay procedures in pollution monitoring programmes is discussed. The results presented here call for further verification to minimize experimental background variability and to enlarge the catalogue of suitable effects criteria. 相似文献
7.
A systematic comparison of summary characteristics for quantifying point patterns in ecology 总被引:1,自引:0,他引:1
Many functional summary characteristics such as Ripley's K function have been used in ecology to describe the spatial structure of point patterns to aid understanding of the underlying processes. However, their use is poorly guided in ecology because little is understood how well single summary characteristics, or a combination of them, capture the spatial structure of real world patterns. Here, we systematically tested the performance of combinations of eight summary characteristics [i.e. pair correlation function g(r), K‐function K(r), the proportion E(r) of points with no neighbor at distance r, the nearest neighbor distribution function D(r), the spherical contact distribution Hs(r), the kth nearest‐neighbor distribution functions Dk(r), the mean distance nn(k) to the kth neighbor, and the intensity function λ( x )]. To this end we used point pattern data covering a wide range of spatial structures including simulated (stationary) as well as real, possibly non‐stationary, patterns on tree species in a tropical forest in Panamá. To measure the information contained in a given combination of summary characteristics we used simulated annealing to reconstruct the observed patterns based only on the limited information provided by this combination and assessed how well other characteristics of the observed pattern were recovered. We found that the number of summary characteristics required to capture the spatial structure of stationary patterns varied between one (for patterns with near random structures) and three (for patterns with complex cluster and superposition structures), but with a robust ranking g(r), Dk(r), and Hs(r) that was largely independent on pattern idiosyncrasies. Stationary summary characteristics [with ranking g(r), Dk(r), Hs(r), E(r)] captured small‐ to intermediate scale properties of non‐stationary patterns, but for describing large‐scale spatial structures the intensity function was required. Our finding revealed that the current practice in ecology of using only one or two summary characteristics bears danger that essential characteristics of more complex patterns would not be detected. The technique of pattern reconstruction presented here has wide applications in ecology. 相似文献
8.
The study of well-preserved Pliocene and Pleistocene s from Emi from Emilia is used to analyze the morphological variations of Mediterranean populations, to depict the relationship between fasciole shape and other morphological characteristics and to describe previously unpublished pedicellar valves. These new data allow to be two species distinguished: s (Müller) a (Müller) and s Pomel; six s Pomel; six species closely related to s are synonymi are synonymized: s and it and s Pomel, i Pomel, i and itS. and s Checchia-R Checchia-Rispoli, x Simonelli a Simonelli and the recent species from Mediterranean, s Mortensen Mortensen. s can be disti can be distinguished from s by its hear by its heart-shaped subanal fasciole, when the s one is reni one is reniform. Moreover, the frontal groove of s is deeper, t is deeper, the primary tubercles of the interambulacra 1 and 4 are less numerous, the petals are shorter and narrower, the labrum is shorter. As far as pedicellariae are concerned, the jags of the large tridentate ones are stronger and the base of the globiferous ones is bigger. Palaeoecological observations on outcrops of the Stirone River, in Parme region, show similar environmental affinities between fossil populations and recent populations from Mediterranean. The s fossils fossils seem to be preserved within their life environment, that is to say in shore sandy substrates.
Résumé
L'étude d'un groupe de spécimens bien conservés appartenant au genre Spatangus, trouvés, dans des localités pliocènes et pléistocènes de l'Émilie, permet d'exposer l'étendue de la variation dans les populations fossiles méditerranéennes, de rechercher les relations entre la forme du fasciole sous-anal et les autres caractères morphologiques et de décrire les valves des pédicellaires, qui n'étaient pas connues jusqu'alors. Ces nouvelles données conduisent à reconnaître deux espèces différentes : s (Müller) e (Müller) et s Pomel ; six Pomel ; six espèces voisines de s doivent prob doivent probablement tomber en synonymie : s et itS et s Pomel, i Pomel, i et itS. a et s Checchia-R Checchia-Rispoli, x Simonelli e Simonelli et l'espèce vivant actuellement en Méditerranée, s Mortensen Mortensen. Des observations paléoécologiques sur un échantillon fossile récolté sur les bords de la rivière Stirone près de Parme montrent des affinités bionomiques semblables chez les populations fossiles et celles vivant en Méditerranée. 相似文献9.
The main aim of this study was to examine the influence of soil properties on the leaching of Cd, Cr, Cu, Ni, Pb, and Zn following the application of polluted sewage sludge to contrasting topsoils. Seventy agricultural soil samples from different parts of Spain were amended with a single dose of sewage sludge (equivalent to 50 t dry weight ha?1) and a column study was performed under controlled conditions. After two, four, and six months of incubation, 283 ml of distilled water (equivalent to a rainfall event of 25 l m?2) was applied. The leachates were then collected and analyzed for metals. For all of the soils considered, the pH was the most important parameter for the control of mobility metals (except for Cu, determined by the sand and soil organic carbon and only to a lesser extent by the soil pH r2 = 0.604, p < 0.001) and was negatively related to all of the studied metals. For Pb and Zn, soil pH was the single soil property explaining their mobility (r2 = 0.411, p < 0.001 for Pb; r2 = 0.713, p < 0.001 for Zn) while for Cd, Cr and Ni, EC, sand and silt also appeared in the statistical models (r2 = 0.753, p < 0.001 for Cd; r2 = 0.366, p < 0.001 for Cr; r2 = 0.784, p < 0.001 for Ni). In the basic soils, soil texture was the most important soil property controlling the mobility of metals (except for that of Pb, which it only weakly predicted). For the acidic-neutral soils, the soil pH was the most important soil property controlling metal mobility (except for that of Cr, which was mainly determined by the pseudo-total Cr content). 相似文献
10.
Erika Chavira-Suárez Alejandro Sandoval Ricardo Felix Mónica Lamas 《Biochemical and biophysical research communications》2011,404(2):678
Normal vision depends on the correct function of retinal neurons and glia and it is impaired in the course of diabetic retinopathy. Müller cells, the main glial cells of the retina, suffer morphological and functional alterations during diabetes participating in the pathological retinal dysfunction. Recently, we showed that Müller cells express the pleiotropic protein potassium channel interacting protein 3 (KChIP3), an integral component of the voltage-gated K+ channels KV4. Here, we sought to analyze the role of KChIP3 in the molecular mechanisms underlying hyperglycemia-induced phenotypic changes in the glial elements of the retina. The expression and function of KChIp3 was analyzed in vitro in rat Müller primary cultures grown under control (5.6 mM) or high glucose (25 mM) (diabetic-like) conditions. We show the up-regulation of KChIP3 expression in Müller cell cultures under high glucose conditions and demonstrate a previously unknown interaction between the KV4 channel and KChIP3 in Müller cells. We show evidence for the expression of a 4-AP-sensitive transient outward voltage-gated K+ current and an alteration in the inactivation of the macroscopic outward K+ currents expressed in high glucose-cultured Müller cells. Our data support the notion that induction of KChIP3 and functional changes of KV4 channels in Müller cells could exert a physiological role in the onset of diabetic retinopathy. 相似文献
11.
Effect of low power ultrasonic radiation on anaerobic biodegradability of sewage sludge 总被引:1,自引:0,他引:1
Chang Liu Bo Xiao Alain Dauta Guifen Peng Shiming Liu Zhiquan Hu 《Bioresource technology》2009,100(24):6217-6222
The effect of low power ultrasonic radiation on anaerobic biodegradability of sewage sludge was investigated. For this purpose, soluble substances and variation of microbial system of sewage sludge subjected to low power ultrasonic radiation were tested. The well known hydromechanical shear forces and heating effect of low frequency ultrasound plays a major role in the sludge pre treatment process. More, the increase of soluble substance may partly result from the destruction of microbial cell by excess ultrasonic pretreatment, which will inhibit the anaerobic process. By orthogonal tests, the optimal parameters were found to be an exposure time of 15 min, ultrasonic intensity of 0.35 W/cm2 and ultrasonic power density of 0.25 W/ml. Under the optimal condition, anaerobic biodegradability of sewage sludge (R(vss/ss) %) was increased by 67.6%. Consequently, it can be concluded that low power ultrasonic pretreatment is a valid method for improving anaerobic biodegradability of sewage sludge. 相似文献
12.
Peter Burt Michel H. Littlewood Simon F. Morgan Brian N. Dancer John C. Fry 《Applied microbiology and biotechnology》1990,33(6):721-724
Summary The aeration performance of two venturi aeration reactors (operating volumes 381 and 251) was studied for an air-water system. It was found that the mass transfer coefficient (k
la) could be described in terms of the superficial gas velocity (V
s) alone by the simple expressionk
La=aV
infb
supS
with constantsa=0.313,b=0.579 for the 38-1 reactor anda=0.214,b=0.534 for the 25-1 reactor. A similar relationship was obeyed when the 38-1 reactor was aerated with a diffuser tile (a=17.0,b=1.52). A linear relationship betweenk
La and gas hold-up was observed for the 38-1 reactor with both venturi and diffuser aeration. The 25-1 reactor was used successfully for the thermophilic aerobic digestion of sewage sludge. A mean sludge temperature rise of 30°C was observed. Chemical oxygen demand, pH, and total solids content of the digested sludge differed significantly from the feed sludge and were similar to values obtained for full-scale thermophilic aerobic digestion. No significant differences between inorganic solids content, dissolved oxygen concentration, or redox potential were observed between feed and digested sludge. 相似文献
13.
Ute Mühlenhardt-Siegel 《Helgoland Marine Research》1990,44(2):189-217
Macrobenthic fauna and sediment parameters were studied at 40 stations representing a 494 km2 survey area in the eastern part of the German Bight and encompassing the sewage sludge dumping site. Data were taken in July
1980, one month after dumping ended, and in April 1981. pH-value, redox potential of the interstitial water, amount of sand
in the sediment as well as total number of species and diversity were lower in the dumping area than outside, whereas alkalinity
and water content of the sediment were higher. Due to mass development of a few species around the dumping site, biomass and
number of individuals were high in July. Abundance and biomass values were lower in April. 2 communities are described and
related to abiotic parameters such as sediment structure. Due to disturbance effects of sewage sludge, 2 stages of the second
successional phase (Pearson & Rosenberg, 1978) were ascertained, described by one of these communities each time. The first
faunal community, characterized by anAbra alba assemblage, describes an early stage of the second successional phase. In summer (July) theAbra alba community showed a wider spatial range than in spring. The other, dominated byNucula nitida, indicated a later stage of the second succession phase that was passing to the third phase.
相似文献
14.
Andrzej Ślęzak 《Journal of biological physics》2000,26(3):235-254
The solute flows were studied in a double-membrane osmotic-diffusive cell, in which two membranes mounted in horizontal planes separate three compartments (l,m,r) containing the non-homogeneous, non-electrolytic binary and ternary solutions. The volume of inter-membrane compartment (m), which is the infinitesimally layer of solution, and volume of external compartments (l and r) fulfill the conditions V
m 0 and V
l =V
r , respectively. In an initial moment, the solution concentrations satisfy the condition (C
o
s
)
l < (C
o
s
)
m >(C
o
s
)
r. The double-membrane osmotic-diffusive cell is composed of two complexes: boundary layer/membrane/boundary layer, mounted in horizontal planes. In the cell, solute flux was measured as a function of concentration and gravitational configuration. The linear dependencies of the solute flux on concentration difference in binary solutions and nonlinear – in ternary solutions were obtained. It was shown that the double-membrane osmotic-diffusive cell has rectifying and amplifying properties of solute flows. 相似文献
15.
Akihiro Ohnishi Akihiro Nagano Naoshi Fujimoto Masaharu Suzuki 《World journal of microbiology & biotechnology》2011,27(2):333-340
The phylogenetic and physiological characteristics of mesophilic and thermophilic bacteria isolated from a field-scale sewage
sludge composter were determined by 16S rDNA and phenotype analyses. Of the 34 mesophilic isolates, 5 (15%), 16 (47%), and
3 (9%) displayed amylase, protease, and lipase activities, respectively. Among these isolates, the following species were
identified based on their 16S rRNA gene sequences: Aneurinibacillus aneurinilyticus, Bacillus fortis, Bacillus subtilis, Brachybacterium paraconglomeratum, Brevibacterium otitidis, Dietzia maris, Pseudomonas xiamenensis, Staphylococcus lentus, Thermobifida fusca, Ureibacillus thermosphaericus, and Vagococcus lutrae. However, 15 isolates could not be identified as known taxa, thus indicating new bacterial taxa. Of these new taxa, it is
likely that NoID A plays an important role in organic matter decomposition during composting based on its physiological characteristics.
Sapporo sewage sludge compost contains a microbial ecosystem with novel bacterial biodiversity, comprising a high percentage
of previously unrecognized species. This study improves our knowledge of the unique bacteria in sewage sludge compost, providing
a future resource for bacterial genetic information and bacterial species of agricultural benefit. 相似文献
16.
Variations in the occurrence of gastrointestinal metazoan parasites in flatfish were examined in relation to sewage sludge dumping at an 'accumulating' and two 'dispersing' dump sites in Scottish coastal waters. The gross disturbance of the benthic communities at the Garroch Head disposal site in the Firth of Clyde and absence of the intermediate hosts of particular parasites was not reflected in the parasite fauna of the long rough dab, Hippoglossoides platessoides . Results indicate that this flatfish host is highly mobile and intermixing within the population masked any localized effects of sludge dumping on parasite transmission at the dump site. The common dab, Limanda limanda , is considered to be relatively static at the St Abb's Head and Bell Rock disposal sites off the Firth of Forth where no evidence of effects of sewage sludge dumping on its metazoan parasite fauna was detected. This is consistent with the results of chemical and biological monitoring of the sites. The value of a parasite-based index of the biological effects of sewage sludge dumping is discussed. 相似文献
17.
Counts of acidophilic iron‐oxidizing bacteria, ratios of S2O3=—S/SO4=—S and Fe+3/Fe+2, and S2O3=—S oxidation potentials were examined over a two‐year period in coal refuse (acid gob) treated with limestone and/or sewage sludge. A non‐amended treatment was used as a control. No significant difference in population counts of acidophilic iron‐oxidizing bacteria were observed between treatments in either year of the study. S2O3=—S/SO4=—S and Fe+3/Fe+2 ratios indicated active sulfur and iron oxidation suggesting that limestone and/or sewage sludge may be ineffective in suppressing pyrite oxidation. Under optimal conditions, S2O3=—S oxidation potentials (in vitro) showed a logarithmic increase in SO4=—S formation for all four treatments over time. The final pH of the treatments following twenty days of perfusion ranged from 3.06 to 3.59. 相似文献
18.
In this segment of a larger multidisciplinary study of the movement and fate of creosote derived compounds in a sand-and-gravel aquifer, we present evidence that the methanogenic degradation of the major biodegradable phenolic compounds and concomitant microbial growth in batch microcosms derived from contaminated aquifer material can be described using Monod kinetics. Substrate depletion and bacterial growth curves were fitted to the Monod equations using nonlinear regression analysis. The method of Marquardt was used for the determination of parameter values that best fit the experimental data by minimizing the residual sum of squares. The Monod kinetic constants (
max
, K
s, Y, and k
d) that describe phenol, 2-, 3-, and 4-methylphenol degradation and concomitant microbial growth were determined under conditions that were substantially different from those previously reported for microcosms cultured from sewage sludge. The K
s values obtained in this study are approximately two orders of magnitude lower than values obtained for the anaerobic degradation of phenol in digesting sewage sludge, indicating that the aquifer microorganisms have developed enzyme systems that are adapted to low nutrient conditions. The values for k
d are much less than
max, and can be neglected in the microcosms. The extremely low Y values, approximately 3 orders of magnitude lower than for the sewage sludge derived cultures, and the very low numbers of microorganisms in the aquifer derived microcosms suggest that these organisms use some unique strategies to survive in the subsurface environment.Abbreviations GC
gas chromatography
- HPLC
high performance liquid chromatography
- LBSSB
likelihood based sum of squares boundaries
- MPN
most probable number
- NLR
nonlinear regression analysis
- OFAG
oxygen free Argon gas
- PCP
pentachlorophenol
- RSS
residual sum of squares
- SRB
sulfate reducing bacteria 相似文献
19.
Drug-resistant bacteria in Continental Shelf sediments 总被引:1,自引:0,他引:1
Fecal indicator bacteria were isolated from water and sediment samples obtained from a sewage sludge disposal site in the Middle Atlantic. Some were found to be resistant to several antimicrobial agents. Isolation of these microbes 30 months after cessation of sludge dumping indicates their survivability in the environment. 相似文献
20.
Fecal indicator bacteria were isolated from water and sediment samples obtained from a sewage sludge disposal site in the Middle Atlantic. Some were found to be resistant to several antimicrobial agents. Isolation of these microbes 30 months after cessation of sludge dumping indicates their survivability in the environment. 相似文献