4,750 research outputs found
Separation of Ground and Low Vegetation Signatures in LiDAR Measurements of Salt-Marsh Environments
No full textLight detection and ranging (LiDAR) has been shown to have a great potential in the accurate characterization of forest systems; however, its application to salt-marsh environments is challenging because the characteristic short vegetation does not give rise to detectable differences between first and last LiDAR returns. Furthermore, the lack of precisely identifiable references (e.g., buildings, roads, etc.) in marsh areas makes the registration and bias correction of the LiDAR data much more difficult than in conventional urban- or forested-area applications. In this paper, we introduce reliable methods to remove random and systematic errors and to register raw data, as well as a new procedure, to determine the optimal filter window size to separate ground and canopy returns. A limited amount of field observations is used to determine the size of the filtering window which produces the minimally biased estimates of the digital terrain model (DTM). The digital surface model (DSM, representing the canopy top) is then obtained in a similar manner, and the digital vegetationmodel (DVM, representing the vegetation height) is computed as the difference between the DSM and the DTM. We apply this procedure to a study marsh within the Venice Lagoon, Italy, and obtain a high-accuracy DTM. The error (z_LiDAR ? z_field) is 2.2 cm, with a standard deviation of 6.4 cm. The comparison of the estimated DVM with field observations shows an underestimation of the height of the canopy top (17.7 cm, on average). The height of the lowest canopy elements (e.g., basal leaves), however, is significantly correlated to the LiDAR-derived DVM, showing that this contains useful information on the canopy structure.Remote SensingAerospace Engineerin
Syngamia florella Stoll 1781
No full textSyngamia florella (Stoll, 1781) Figs 64, 132, 178 Tinea florella Stoll in Cramer & Stoll, 1781: 114, pl. 348 fig. L. Syngamia florella (Stoll): Peck et al. 1998: 227. ‒ Causton et al., 2006: 141. ‒ Roque-Albelo & Landry, 2015. Material examined: 9 ♂, 11 ♀, 46 of undetermined sex from the Galápagos Islands: – Floreana: Charles [no precise locality]; Punta Cormoran; close to Loberia, GPS: elev[ation]. 6 m, S 01° 17.002’, W 90° 29.460’. – Genovesa: Bahía Darwin. – Isabela: Alcedo, lado NE, low arid zone bosq[ue]. palo santo; V[olcan]. Darwin, 300 m elev.; 1 km W P[uer]to Villamil; 2 km Puerto Villamil; 8.5 km N Pto Villamil; ± 15 km N Pto Villamil; Sierra Negra, 1000 m alt[itude]. – San Cristóbal: Chatham [no precise locality]; 1 km S El Progreso; El Junco, east side, GPS: 654 m elev., S 00° 53.734’, W 89° 28.727’; pampa zone. – Santa Cruz: Agr[iculture]. Zone; Tortuga Res[erve]. W S[an]ta Rosa; Horneman Farm, 220 m elev.; agriculture zone, near (NNW) Bella Vista, GPS: 223 m elev., S 00° 41.297’, W 90° 19.670’; NNW Bella Vista, GPS: 225 m elev., S 00° 41.293’, W 90° 19.665’; Finca Vilema, 2 km W Bella Vista; 2 km W Bella Vista; Los Gemelos; Media Luna, pampa zone. – Santiago: Bahía Espumilla; La Bomba, 6 m elev., S 00° 11.151’, W 90° 42.052’; 200 m elev.; Aguacate [camp], 520 m elev.; Central [camp], 700 m; Jaboncillo [camp], ± 850 m elev. Deposited in BMNH, CAS, CDRS, CNC, MCZ, and MHNG. Diagnosis: The diminutive Syngamia florella (Stoll) is one of the most strikingly patterned and coloured species of Spilomelinae in the Galápagos (Fig. 64). The broad orange yellow markings of the thorax and both wings over a dark brown ground colour as well as the bright orange abdomen with patches of shining blue scales are not found in any other species. The wingspan is between 15 and 19 mm. Biology: The known host plants of this species are in the Rubiaceae genera Borreria and Spermacoce (Heppner, 2003; Robinson et al., 2014). In the Galápagos specimens have been collected from the littoral zone to higher zones up to about 1000 m, in cultivated as well as pristine habitats, and from February until June and October. Distribution: Described from Surinam this species is widespread in the Western Hemisphere as attest the countries recorded from the labels of specimens in the BMNH: USA, Bahamas, Grand Cayman, Jamaica, St Vincent, Dominica, Cuba, Santo Domingo, Grenada, Tobago, Trinidad, Mexico, Costa Rica, Guatemala, Honduras, Panama, Venezuela, British Guiana, Brazil, Ecuador, Paraguay, Argentina. In addition, the MHNG has specimens from Martinique and French Guiana. Patterson et al. (2015) report it from several US States of the south east, with most records from Florida, Georgia, and Texas. Already in 1854, Guenée wrote that this species was very common in all of Meridional America. In the Galápagos specimens were collected on several islands as noted above in the Material examined. In addition, a CDRS specimen labelled simply ‘92’ refers to notes in a notebook in the CDRS adding the localities of Cerro Azul on Isabela and Media Luna on Santa Cruz. Remarks: The original description was checked to identify the Galapagos specimens, but there is no real description, rather an illustration that is not very convincing. Stoll (1781) mentioned that he was told that this species was found in Surinam on many different sorts of flowers and in great abundance. My Galápagos specimens match the specimens identified as this species in the BMNH.Published as part of Bernard Landry, 2016, Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador, pp. 315-399 in Revue suisse de Zoologie 123 (2) on pages 389-391, DOI: 10.5281/zenodo.15530
Comparison of two simple high-frequency earthing electrodes
No full textLightning strikes on high-voltage transmission lines may create hazardous touch potentials on adjacent substation equipment and damage to control equipment. When designing suitable substation earthing electrodes to overcome this problem and safely dissipate the transient fault currents to ground, it is essential to consider the behaviour of the current flow. The steady-state frequency equivalent to a lightning strike is at least 0.25 MHz, which corresponds to a current skin depth d of about 10m in homogeneous soil of conductivity 0.01 Sm-1. This surface effect causes the impedance of an electrode system to be considerably larger than the power frequency resistance. Thus, a dedicated electrode is normally placed in parallel with the low-frequency earthing system, usually taking the form of a simple vertical rod of copper-coated steel about 5m long. However, the work presented in this paper suggests that a long rod is not ideal for the purpose. Using a relatively simple numerical finite-difference procedure it has been found that a flat disc electrode parallel to the surface of the ground achieves a significant improvement over the performance of a vertical rod. Both rod and disc have been solved in the frequency domain, but the rod has also been analysed in time-stepping form so that the peak voltage for a given imposed current can be compared with that deduced from the equivalent steady-state complex impedance
CALCULATED SPECTROSCOPIC PROPERTIES FOR CLUSTER ANIONS OF TYPE (Hal: F, Cl, Br, and I)
No full textP. Botschwina, T. Dutoi, M. Mladenovi\'c, Rainer Oswald, S. Schmatz and H. Stoll, Faraday Discuss., in press. P. Botschwina and H. Stoll, Phys. Chem. Chem. Phys., in press.Author Institution: Universit\""at G\""ottingen; Institut f\""ur Physikalische Chemie, Universit\""at G\""ottingen; Institut f\""ur Physikalische Chemie, Universit\""at StuttgartLarge-scale coupled cluster calculations were carried out for the complexes formed by a halide anion and an acetylene molecule, all of which have linear equilibrium . The complex is most strongly bound extremely anharmonic. A comparative discussion of various spectroscopic properties is given
Politikberatung im Vogelgrippendilemma
No full textWeingart P. Politikberatung im Vogelgrippendilemma. In: Kraul M, Stoll P-T, eds. Wissenschaftliche Politikberatung. Göttingen: Wallstein; 2011: 133-145
Dataset supplementing Stoll, J., Thrun, M., Nuthmann, A., & Einhäuser, W. (2015). Overt attention in natural scenes: Objects dominate features. Vision Research, 107, 36-48. doi: 10.1016/j.visres.2014.11.006
No full text<p>These data supplement the publication</p>
<p>Stoll, J., Thrun, M., Nuthmann, A., & Einhäuser, W. (2015). Overt attention in natural scenes: Objects dominate features. Vision Research, 107, 36-48. doi: 10.1016/j.visres.2014.11.006</p>
<p>and be used freely for scientific purposes provided the aforementioned paper is appropriately cited.</p>
<p>Note that the image files cannot be provided on this site due to copyright restrictions.</p>
<p>The dataset contains the following files:</p>
<p>maps_01.mat - maps_72.mat:</p>
<p>For each image the 6 maps used in the paper are contained, the maps of experiment 1 are labelled as in the paper (AWS, OOM, nOOM, PVL,UNI), AWS2 is the AWS map for the modified stimuli of experiments 2 and 3.</p>
<p>exp?_fixations.mat contains all fixations of the respective experiment.</p>
<p>For experiment 1, there are the variables xFix, yFix, durFix, which contain the x position, the y condition, and the fixation duration of each fixation. Dimensions are images x subjects x fixation number, where the first fixation is the 0th (initial) fixation. The variable condition (image x subject) contains the condition in which the respective image was shown to the subject. For the main analysis only the "0" condition was used, refer to the paper's appendix for the other conditions.</p>
<p>For experiment 2 and 3, variables are called xFixByImage, yFixByImage, dFixByImage and the dimensions are subject x image x fixation number. In addition tFixByImage contains the start of the fixation relative to trial onset (negative for the 0th fixation).<br>
In both cases, empty entries are filled with nans.</p>
<p><br>
computeROC.m is a helper function called by other functions.</p>
<p><br>
figure1.m through figure7.m reproduce the figures from the paper to exemplify data usage.</p>
<p> </p>The research was supported by the German Research Foundation (DFG; grants: EI 852/1 and SFB/TRR 135)
Technikfolgenabschätzung - Ein utopisches Projekt?
No full textBora A. Technikfolgenabschätzung - Ein utopisches Projekt? In: Kraul M, Stoll P-T, eds. Wissenschaftliche Politikberatung. Göttingen: Wallstein; 2011: 189-206
Treatment of mobile vertebral instability with Dynesys
No full textThe goal of dynamic stabilization with Dynesis is to realign and stabilize one or more intervertebral lumbar or lumbosacral segments in a position close to the normal anatomical position, with the intent of encouraging return to improve physiology while enabling a certain degree of range of motion.
At present time, more than 15,000 surgical procedures have been performed in over 15 different countries. The longest follow-up period is 10 year
Microbiome Dynamics Associated With the Atacama Flowering Desert
No full textIn a desert, plants as holobionts quickly respond to resource pulses like precipitation. However, little is known on how environment and plants modulate the rhizosphere-associated microbiome. As a model species to represent the Atacama Desert bloom, Cistanthe longiscapa (Montiaceae family) was selected to study the influence of abiotic and biotic environment on the diversity and structure of the microbiota associated to its rhizosphere. We analyzed the rhizosphere and soil microbiome along a North-South precipitation gradient and between a dry and rainy year by using Illumina high−throughput sequencing of 16S rRNA gene fragments and ITS2 regions for prokaryotes and fungi, respectively. In the rhizosphere of C. longiscapa the microbiota clearly differs in composition and structure from the surrounding bulk soil. The fungal and bacterial communities respond differently to environmental conditions. The diversity and richness of fungal OTUs were negatively correlated with aridity, as predicted. The community structure was predominantly influenced by other soil characteristics (pH, organic matter content) but not by aridity. In contrast, diversity, composition, and structure of the bacterial community were not influenced by aridity or any other evaluated soil parameter. These findings coincide with the identification of mainly site-specific microbial communities, not shared along the sites. These local communities contain a group of OTUs, which are exclusive to the rhizosphere of each site and presumably vertically inherited as seed endophytes. Their ecological functions and dispersal mechanisms remain unclear. The analysis of co-occurrence patterns highlights the strong effect of the desert habitat over the soil- and rhizosphere-microbiome. The site-independent enrichment of only a small bacterial cluster consistently associated with the rhizosphere of C. longiscapa further supports this conclusion. In a rainy year, the rhizosphere microbiota significantly differed from bulk and bare soil, whereas in a dry year, the community structure of the former rhizosphere approximates to the one found in the bulk. In the context of plant–microbe interactions in desert environments, our study contributes new insights into the importance of aridity in microbial community structure and composition, discovering the influence of other soil parameters in this complex dynamic network, which needs further to be investigated
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