79 research outputs found
Observation of a local gravity potential isosurface by airborne lidar of Lake Balaton, Hungary
Airborne lidar is a remote sensing method commonly
used for mapping surface topography in high resolution.
A water surface in hydrostatic equilibrium theoretically
represents a gravity potential isosurface. Here we compare
lidar-based ellipsoidal water surface height measurements all
around the shore of a major lake with a local high-resolution
quasi-geoid model. The ellipsoidal heights of the 87 km2 we
sampled all around the shore of the 597 km2 lake surface vary
by 0.8m and strong spatial correlation with the quasi-geoid
undulation was calculated (R2 = 0.91). After subtraction of
the local geoid undulation from the measured ellipsoidal water
surface heights, their variation was considerably reduced.
Based on a network of water gauge measurements, dynamic
water surface heights were also successfully corrected for.
This demonstrates that the water surface heights of the lake
were truly determined by the local gravity potential.We conclude
that both the level of hydrostatic equilibrium of the lake
and the accuracy of airborne lidar were sufficient for identifying
the spatial variations of gravity potential
RIGOROUS STRIP ADJUSTMENT OF AIRBORNE LASERSCANNING DATA BASED ON THE ICP ALGORITHM
Airborne Laser Scanning (ALS) is an efficient method for the acquisition of dense and accurate point clouds over extended areas. To
ensure a gapless coverage of the area, point clouds are collected strip wise with a considerable overlap. The redundant information
contained in these overlap areas can be used, together with ground-truth data, to re-calibrate the ALS system and to compensate for
systematic measurement errors. This process, usually denoted as strip adjustment, leads to an improved georeferencing of the ALS
strips, or in other words, to a higher data quality of the acquired point clouds. We present a fully automatic strip adjustment method that
(a) uses the original scanner and trajectory measurements, (b) performs an on-the-job calibration of the entire ALS multisensor system,
and (c) corrects the trajectory errors individually for each strip. Like in the Iterative Closest Point (ICP) algorithm, correspondences
are established iteratively and directly between points of overlapping ALS strips (avoiding a time-consuming segmentation and/or
interpolation of the point clouds). The suitability of the method for large amounts of data is demonstrated on the basis of an ALS block
consisting of 103 strips
Primary succession and its driving variables – a sphere-spanning approach applied in proglacial areas in the upper Martell Valley (Eastern Italian Alps)
Climate change and the associated glacier retreat lead to
considerable enlargement and alterations of the proglacial systems. The
colonisation of plants in this ecosystem was found to be highly dependent on
terrain age, initial site conditions and geomorphic disturbances. Although
the explanatory variables are generally well understood, there is little
knowledge on their collinearities and resulting influence on proglacial
primary succession. To develop a sphere-spanning understanding of vegetation
development, a more interdisciplinary approach was adopted. In the
proglacial areas of FĂĽrkeleferner, Zufallferner and Langenferner (Martell
Valley, Eastern Italian Alps), in total 65 plots of 5×2 m were
installed to perform the vegetation analysis on vegetation cover, species
number and species composition. For each of those, 39 potential explanatory
variables were collected, selected through an extensive literature review.
To analyse and further avoid multicollinearities, 33 of the explanatory
variables were clustered via principal component analysis (PCA) to five
components. Subsequently, generalised additive models (GAMs) were used to
analyse the potential explanatory factors of primary succession. The results
showed that primary succession patterns were highly related to the first
component (elevation and time), the second component (solar radiation),
the third component (soil chemistry), the fifth component
(soil physics) and landforms. In summary, the analysis of all explanatory
variables together provides an overview of the most important influencing
variables and their interactions; thus it provides a basis for the debate on future
vegetation development in a changing climate.</p
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Open science, communal culture, and women’s participation in the movement to improve science
Science is undergoing rapid change with the movement to improve science focused largely on reproducibility/replicability and open science practices. This moment of change—in which science turns inward to examine its methods and practices—provides an opportunity to address its historic lack of diversity and noninclusive culture. Through network modeling and semantic analysis, we provide an initial exploration of the structure, cultural frames, and women’s participation in the open science and reproducibility literatures (n = 2,926 articles and conference proceedings). Network analyses suggest that the open science and reproducibility literatures are emerging relatively independently of each other, sharing few common papers or authors. We next examine whether the literatures differentially incorporate collaborative, prosocial ideals that are known to engage members of underrepresented groups more than independent, winner-takes-all approaches. We find that open science has a more connected, collaborative structure than does reproducibility. Semantic analyses of paper abstracts reveal that these literatures have adopted different cultural frames: open science includes more explicitly communal and prosocial language than does reproducibility. Finally, consistent with literature suggesting the diversity benefits of communal and prosocial purposes, we find that women publish more frequently in high-status author positions (first or last) within open science (vs. reproducibility). Furthermore, this finding is further patterned by team size and time. Women are more represented in larger teams within reproducibility, and women’s participation is increasing in open science over time and decreasing in reproducibility. We conclude with actionable suggestions for cultivating a more prosocial and diverse culture of science
Construcción de una cámara anecoica para la caracterización de la pérdida de transmisión sonora
A candidate ion-retaining state in the inward-facing conformation of sodium/galactose symporter: Clues from atomistic simulations
The recent Vibrio parahaemolyticus sodium/galactose (vSGLT) symporter crystal structure captures the protein in an inward-facing substrate-bound conformation, with the sodium ion placed, by structural alignment, in a site equivalent to the Na2 site of the leucine transporter (LeuT). A recent study, based on molecular dynamics simulations, showed that the sodium ion spontaneously leaves its initial position diffusing outside vSGLT, toward the intracellular space. This suggested that the crystal structure corresponds to an ion-releasing state of the transporter. Here, using metadynamics, we identified a more stable Na+ binding site corresponding to a putative ion-retaining state of the transporter. In addition, our simulations, consistently with mutagenesis studies, highlight the importance of D189 that, without being one of the NA(+)-coordinating residues, regulates its binding/release
Probabilistic fire spread forecast as a management tool in an operational setting
Background: An approach to predict fire growth in an operational setting, with the
potential to be used as a decision-support tool for fire management, is described and
evaluated. The operational use of fire behaviour models has mostly followed a deterministic
approach, however, the uncertainty associated with model predictions needs
to be quantified and included in wildfire planning and decision-making process during
fire suppression activities. We use FARSITE to simulate the growth of a large wildfire.
Probabilistic simulations of fire spread are performed, accounting for the uncertainty
of some model inputs and parameters. Deterministic simulations were performed for
comparison. We also assess the degree to which fire spread modelling and satellite
active fire data can be combined, to forecast fire spread during large wildfires events.
Results: Uncertainty was propagated through the FARSITE fire spread modelling system
by randomly defining 100 different combinations of the independent input variables
and parameters, and running the correspondent fire spread simulations in order
to produce fire spread probability maps. Simulations were initialized with the reported
ignition location and with satellite active fires. The probabilistic fire spread predictions
show great potential to be used as a fire management tool in an operational setting,
providing valuable information regarding the spatial–temporal distribution of burn
probabilities. The advantage of probabilistic over deterministic simulations is clear
when both are compared. Re-initializing simulations with satellite active fires did not
improve simulations as expected.
Conclusion: This information can be useful to anticipate the growth of wildfires
through the landscape with an associated probability of occurrence. The additional
information regarding when, where and with what probability the fire might be in the
next few hours can ultimately help minimize the negative environmental, social and
economic impacts of these firesinfo:eu-repo/semantics/publishedVersio
Fleas as parasites of the family Canidae
Historically, flea-borne diseases are among the most important medical diseases of humans. Plague and murine typhus are known for centuries while the last years brought some new flea-transmitted pathogens, like R. felis and Bartonella henselae. Dogs may play an essential or an accidental role in the natural transmission cycle of flea-borne pathogens. They support the growth of some of the pathogens or they serve as transport vehicles for infected fleas between their natural reservoirs and humans. More than 15 different flea species have been described in domestic dogs thus far. Several other species have been found to be associated with wild canids. Fleas found on dogs originate from rodents, birds, insectivores and from other Carnivora. Dogs therefore may serve as ideal bridging hosts for the introduction of flea-borne diseases from nature to home. In addition to their role as ectoparasites they cause nuisance for humans and animals and may be the cause for severe allergic reactions
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