933 research outputs found
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Reproductive Ecology of Ospreys and Peregrine Falcons
Because ospreys (Pandion haliaetus) nesting along Delaware Bay have retained low productivity and little population growth since the mid-1970s, during 1987 and 1988 we compared reproductive dynamics of Bay ospreys with a recovering colony nesting along the Atlantic Coast. Productivity of Delaware Bay ospreys remains low because 48% of nests initiated along the Bay failed, compared to only 23% of nests along the Atlantic Coast. Only 49% of eggs laid in the Bay colony hatched, compared to 66% along the Atlantic, and 25% of those young successfully hatched near the Bay were preyed upon by great horned owls (Bubo virginianus). Higher frequence of unhatched eggs and thinner eggshells indicate that Bay ospreys may still be affected by environmental contaminants present in the Delaware estuary.
Many factors may affect differential rates of growth within a species, including food supply, weather, and parental ability. We examined growth rate and brood reduction of ospreys nesting in an area supporting abundant, available prey along the Mid-Atlantic Coast. Growth of ospreys from this area was best explained by a logistic growth curve (k = 0.173). We found little difference in growth related to year, clutch size, and brood reduction, although brood reduction occurred most often in larger broods, probably because of large disparities in within-brood size of nestlings. We believe large geographic differences in osprey growth are a function of food availability, while smaller differences -- reflected in brood reduction -- may be a function of a male\u27s age, experience, or ability to supply food.
Reestablishment of peregrine falcons (Falco peregrinus) as breeding birds in the eastern United States has been a highlight in endangered species management and recovery. To assess this reestablished population in New Jersey, we examined numbers, reproductive success, and eggshell thinning of peregrines during 1979-1988. From several pairs studied intensively during 1987 and 1988, we describe regional differences in reproductive success, nestling behaviors, and prey of these falcons. Although productivity compares favorably with stable populations, eggshells of New Jersey peregrines are thinning with time. This decrease in statewide-eggshell thinning and low hatching success of eggs along Delaware Bay indicates continued exposure to environmental contaminants, probably from their migratory prey
Data on geochemical and hydraulic properties of a characteristic confined/unconfined aquifer system of the younger Pleistocene in northeast Germany
The paper presents a database of hydrochemical and hydraulic groundwater
measurements of a younger Pleistocene multilayered, unconfined/confined
aquifer system in NE Germany. The Institute of Landscape Hydrology of the
Leibniz Centre for Agricultural Landscape Research (ZALF) operates seven
groundwater monitoring wells in the Quillow catchment located in the Uckermark
region (federal state of Brandenburg, Germany). From July 2000 to March 2014,
water samples were collected periodically on different days of the year and at
depths between 3 and 5 m (shallow wells) and 16 and 24 m (deeper wells) below
the surface. The parameters pH value, redox potential, electric conductivity,
water temperature, oxygen content, spectral absorption coefficient and
concentration of hydrogen carbonate, ammonium, phosphate, chloride, bromide,
nitrite, sulfate, sodium, potassium, magnesium, calcite, dissolved organic
carbon, iron(II) and manganese were determined for each sample
(doi:10.4228/ZALF.2000.266). The measurements, taken over a period of 14
years, include a high variation of hydraulic situations represented by a
corresponding database of 19 000 recorded groundwater heads. The hydraulic
head was measured between 2000 and 201
Hybrid Wavelet-Support Vector Classifiers
The Support Vector Machine (SVM) represents a new and very promising technique for machine learning tasks involving classification, regression or novelty detection. Improvements of its generalization ability can be achieved by incorporating prior knowledge of the task at hand. We propose a new hybrid algorithm consisting of signal-adapted wavelet decompositions and SVMs for waveform classification. The adaptation of the wavelet decompositions is tailormade for SVMs with radial basis functions as kernels. It allows the optimization Of the representation of the data before training the SVM and does not suffer from computationally expensive validation techniques. We assess the performance of our algorithm against the background of current concerns in medical diagnostics, namely the classification of endocardial electrograms and the detection of otoacoustic emissions. Here the performance of SVMs can significantly be improved by our adapted preprocessing step
Parameter Detection of Thin Films From Their X-Ray Reflectivity by Support Vector Machines
Reflectivity measurements are used in thin film investigations for determining the desity and the thickness of layered structures and the roughness of external and internal surfaces. From the mathematical point of view the deduction of these parameters from a measured reflectivity curve represents an inverSe ptoblem. At present, curve fitting procedures, based to a large extent on expert knowledge are commonly used in practice. These techniques suffer from a low degree of automation. In this paper we present a new approach to the evaluation of reflectivity measurements using support vector machines. For the estimation of the different thin film parameters we provide sparse approximations of vector-valued functions, where we work in parallel on the same data sets. Our support vector machines were trained by simulated reflectivity curves generated by the optical matrix method. The solution of the corresponding quadratic programming problem makes use of the SVMTorch algorithm. We present numerical investigations to assess the performance of our method using models of practical relevance. It is concluded that the approximation by support vector machines represents a very promising tool in X-ray reflectivity investigations and seems also to be applicable for a much broader range of parameter detection problems in X-ray analysis
Lagrangian Motion Magnification with Double Sparse Optical Flow Decomposition
Motion magnification techniques aim at amplifying and hence revealing subtle
motion in videos. There are basically two main approaches to reach this goal,
namely via Eulerian or Lagrangian techniques. While the first one magnifies
motion implicitly by operating directly on image pixels, the Lagrangian
approach uses optical flow techniques to extract and amplify pixel
trajectories. Microexpressions are fast and spatially small facial expressions
that are difficult to detect. In this paper, we propose a novel approach for
local Lagrangian motion magnification of facial micromovements. Our
contribution is three-fold: first, we fine-tune the recurrent all-pairs field
transforms for optical flows (RAFT) deep learning approach for faces by adding
ground truth obtained from the variational dense inverse search (DIS) for
optical flow algorithm applied to the CASME II video set of faces. This enables
us to produce optical flows of facial videos in an efficient and sufficiently
accurate way. Second, since facial micromovements are both local in space and
time, we propose to approximate the optical flow field by sparse components
both in space and time leading to a double sparse decomposition. Third, we use
this decomposition to magnify micro-motions in specific areas of the face,
where we introduce a new forward warping strategy using a triangular splitting
of the image grid and barycentric interpolation of the RGB vectors at the
corners of the transformed triangles. We demonstrate the very good performance
of our approach by various examples
Disparity and optical flow partitioning using extended Potts priors
This paper addresses the problems of disparity and optical flow partitioning based on the brightness invariance assumption. We investigate new variational approaches to these problems with Potts priors and possibly box constraints. For the optical flow partitioning, our model includes vector-valued data and an adapted Potts regularizer. Using the notion of asymptotically level stable (als) functions, we prove the existence of global minimizers of our functionals. We propose a modified alternating direction method of multipliers. This iterative algorithm requires the computation of global minimizers of classical univariate Potts problems which can be done efficiently by dynamic programming. We prove that the algorithm converges both for the constrained and unconstrained problems. Numerical examples demonstrate the very good performance of our partitioning method
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Human impacts on the ecology of bald eagles in interior Alaska
To assess the consequences of increased recreational activity on bald eagles (Haliaeetus leucocephalus), we studied factors that influenced their behavior and reproductive success in the Gulkana River basin, Alaska, from 1989 to 1993. Both extrinsic and intrinsic factors were associated with reproductive success. Productivity averaged 0.86 young fledged per occupied territory (SE = 0.05) with 59% nest success (n = 274), but productivity varied among years and subdrainages (P < 0.02). Further, productivity and nest success, but not density, of pairs along the river corridor were negatively associated with levels of human activity (P = 0.037). Pairs that were successful one year were more likely to occupy the same territories, less likely to change nest locations within a territory, more likely to be successful, and fledged more offspring the following year compared to pairs that were previously unsuccessful. Most nesting failure (92%) occurred during incubation. Annual and regional variability in reproductive success of northern bald eagle populations may result from susceptibility to severe spring weather conditions during incubation. Behavior of breeding eagles changed when humans camped near ( 100 m) versus far ( 500 m) from nests (P = 0.0036). Adults decreased the time they fed nestlings and themselves (-30%), preened (-53%), slept (-5 6%) and maintained nests (-50%), but increased the time they brooded nestlings (14%). Further, adults decreased the frequency with which they performed most nesting behaviors, including the amount of prey they consumed at nests (-26%) and fed to nestlings (-29%). Our results show that human activity near nests altered breeding behavior, and suggest that if disturbances in nesting territories were sustained, eagle populations could be affected adversely. The context in which human-eagle encounters occurred affected eagle responses to boating activity. The distance a disturbance was first visible to eagles, the distance they perched from the river, perch height, eagle age, julian date, and ambient temperature were among those factors that influenced both flush response and flush distance of nonbreeding eagles. Breeding adults were less likely to flush and flushed at shorter distances (87.5 ± 10.2 m) than nonbreeding adults (113.0 ± 4.5 in) to approaching boats (P < 0.024). Based on our studies, we recommend a series of strategies to minimize the adverse effects of human activity on breeding and nonbreeding eagles
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