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Intensity Threshold (intensity + threshold)
Selected AbstractsRunoff and soil loss under individual plants of a semi-arid Mediterranean shrubland: influence of plant morphology and rainfall intensityEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2006E. Bochet Abstract The influence of plant morphology and rainfall intensity on soil loss and runoff was determined at the plant scale for three representative species of a semi-arid patchy shrubland vegetation of east Spain, representing contrasting canopy structures and plant phenologies (Rosmarinus officinalis, Anthyllis cytisoides and Stipa tenacissima). Twenty-seven microplots of less than 1 m2, each containing one single plant, were built to quantify runoff volume and sediment yield under the canopies of the three species. Runoff and rates of soil loss measured in these plots under natural rainfall conditions were compared with control microplots built in the bare inter-plant areas. Precipitation was automatic-ally recorded and rainfall intensity calculated over a two-year period. Results indicated that individual plants played a relevant role in interrill erosion control at the microscale. Compared with a bare soil surface, rates of soil loss and runoff reduction varied strongly depending on the species. Cumulative soil loss was reduced by 94·3, 88·0 and 30·2 per cent, and cumulative runoff volume was reduced by 66·4, 50·8 and 18·4 per cent under the Rosmarinus, Stipa and Anthyllis canopies, respectively, compared with a bare surface. Anthyllis was significantly less efficient than the two other species in reducing runoff volume under its canopy. Differences between species could only be identified above a rainfall intensity threshold of 20 mm h,1. The different plant morphologies and plant compon-ents explained the different erosive responses of the three species. Canopy cover played a major role in runoff and soil loss reduction. The presence of a second layer of protection at the soil surface (litter cover) was fundamental for erosion control during intense rainfall. Rainfall intensity and soil water status prior to rainfall strongly influenced runoff and soil loss rates. The possible use of these species in restoration programmes of degraded areas is discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Definition of an exercise intensity threshold in a challenge test to diagnose food-dependent exercise-induced anaphylaxisALLERGY, Issue 10 2009M. Loibl No abstract is available for this article. [source] Modelling cross-hybridization on phylogenetic DNA microarrays increases the detection power of closely related speciesMOLECULAR ECOLOGY RESOURCES, Issue 1 2009JULIA C. ENGELMANN Abstract DNA microarrays are a popular technique for the detection of microorganisms. Several approaches using specific oligomers targeting one or a few marker genes for each species have been proposed. Data analysis is usually limited to call a species present when its oligomer exceeds a certain intensity threshold. While this strategy works reasonably well for distantly related species, it does not work well for very closely related species: Cross-hybridization of nontarget DNA prevents a simple identification based on signal intensity. The majority of species of the same genus has a sequence similarity of over 90%. For biodiversity studies down to the species level, it is therefore important to increase the detection power of closely related species. We propose a simple, cost-effective and robust approach for biodiversity studies using DNA microarray technology and demonstrate it on scenedesmacean green algae. The internal transcribed spacer 2 (ITS2) rDNA sequence was chosen as marker because it is suitable to distinguish all eukaryotic species even though parts of it are virtually identical in closely related species. We show that by modelling hybridization behaviour with a matrix algebra approach, we are able to identify closely related species that cannot be distinguished with a threshold on signal intensity. Thus this proof-of-concept study shows that by adding a simple and robust data analysis step to the evaluation of DNA microarrays, species detection can be significantly improved for closely related species with a high sequence similarity. [source] Temporal correlations and clustering of landslidesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2010Annette Witt Abstract This paper examines temporal correlations and temporal clustering of a proxy historical landslide time series, 2255 reported landslides 1951,2002, for an area in the Emilia-Romagna Region, Italy. Landslide intensity is measured by the number of reported landslides in a day (DL) and in an ,event' (Sevent) of consecutive days with landsliding. The non-zero values in both time series DL and Sevent are unequally spaced in time, and have heavy-tailed frequency-size distributions. To examine temporal correlations, we use power-spectral analysis (Lomb periodogram) and surrogate data analysis, confronting our original DL and Sevent time series with 1000 shuffled (uncorrelated) versions. We conclude that the landslide intensity series DL has strong temporal correlations and Sevent has likely temporal correlations. To examine temporal clustering in DL and Sevent, we consider extremes over different landslide intensity thresholds. We first examine the statistical distribution of interextreme occurrence times, ,, and find Weibull distributions with parameter , << 1·0 [DL] and , < 1·0 [Sevent]; thus DL and Sevent each have temporal correlations, but Sevent to a lesser degree. We next examine correlations between successive interextreme occurrence times, ,. Using autocorrelation analysis applied to ,, combined with surrogate data analysis, we find for DL linear correlations in ,, but for Sevent inconclusive results. However, using Kendall's rank correlation analysis we find for both DL and Sevent the series of , are strongly correlated. Finally, we apply Fano Factor analysis, finding for both DL and Sevent the timings of extremes over a given threshold exhibit a fractal structure and are clustered in time. In this paper, we provide a framework for examining time series where the non-zero values are strongly unequally spaced and heavy-tailed, particularly important in the Earth Sciences due to their common occurrence, and find that landslide intensity time series exhibit temporal correlations and clustering. Many landslide models currently are designed under the assumption that landslides are uncorrelated in time, which we show is false. Copyright © 2010 John Wiley & Sons, Ltd. [source] Bigger is better: implications of body size for flight ability under different light conditions and the evolution of alloethism in bumblebeesFUNCTIONAL ECOLOGY, Issue 6 2007A. KAPUSTJANSKIJ Summary 1In social insects, reproductive success and survival of the colony critically depend on the colony's ability to efficiently allocate workers to the various tasks which need to be performed. In bumblebees, workers show a large variation of body size within a colony. Large workers tend to leave the nest and forage for nectar and pollen, whereas small workers stay inside the nest and fulfill nest duties. It was speculated that size-related differences of the sensory system might contribute to alloethism found in bumblebee colonies. 2In the first part, we investigated how body size determines eye morphology. We measured several eye parameters of Bombus terrestris workers and drones. In both, workers and drones, larger individuals had larger eyes with larger facet diameters, more ommatidia and larger ocelli. At similar body size, drones exhibited larger eyes and ocelli compared to workers. Due to theoretical considerations, we predict that large individuals with large eyes should be better able to operate in illumination conditions of lower intensity than small individuals, since ommatidial sensitivity is proportional to the square of facet diameter. 3In the second part, we tested this prediction. In a behavioural experiment, we first caught bumblebees of various sizes in the field and then determined the lowest light intensity level at which they are just able to fly under controlled laboratory conditions. We tested workers of B. terrestris and B. pascuorum, and workers and drones of B. lapidarius. Large bumblebees were able to fly under lower light levels compared to small bees, with light intensity thresholds ranging from 1·1 to 5·5 lux. 4Our results indicate that the increased light sensitivity of the visual system of large bumblebees allows them to fly under poor light conditions, for example, very early in the morning or late at dusk. This is of potential benefit to the survival of a bumblebee colony since flowers that open early in the morning usually have accumulated a relatively high amount of nectar and pollen throughout the night, and large bumblebees can utilize these resources earlier than most other bees. Thus, our findings have important implications for the understanding of the functional significance and evolution of alloethism in bumblebee colonies. [source] Photothermal and accompanied phenomena of selective nanophotothermolysis with gold nanoparticles and laser pulsesLASER PHYSICS LETTERS, Issue 11 2008V.K. Pustovalov Abstract In medical applications of laser and nanotechnology to diagnosis and treat cancer or microorganisms, understanding of lased-induced photothermal (PT) and accompanied phenomena around nanoparticles are crucial for optimization and bringing this promising technology to bedside. We analyzed the main Ptbased effects in and around gold nanoparticles under action of short (nano-, pico-, and femtosecond) laser pulses with focus on photoacoustic effects due to the thermal expansion of nanoparticles and liquid around them, thermal protein denaturation, explosive liquid vaporization, melting and evaporation of nanoparticle, optical breakdown initiated by nanoparticles and accompanied to shock waves and explosion (fragmentation) of gold nanoparticles. Characteristic parameters for these processes such as the temperature and pressures levels, and laser intensity thresholds among others are summarized to provide basis for comparison of different mechanisms of selective nanophotothermolysis and diagnostics of different targets (e.g., cancer cells, bacteria, viruses). (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] | ||||||||||