14,275 research outputs found
Nine new species of Begonia (Begoniaceae) from South and West Sulawesi, Indonesia
Nine new species of Begonia (Begoniaceae), Begonia comestibilis D.C.Thomas & Ardi, B. insueta D.C.Thomas & Ardi, B. lasioura D.C.Thomas & Ardi, B. nobmanniae D.C.Thomas & Ardi, B. prionota D.C.Thomas & Ardi, B. rantemarioensis D.C.Thomas & Ardi, B. sanguineopilosa D.C.Thomas & Ardi, B. torajana D.C.Thomas & Ardi and B. vermeulenii D.C.Thomas, are described from South and West Sulawesi, Indonesia. All belong to Begonia section Petermannia. Proposed conservation categories for these species are Vulnerable (VU) for Begonia comestibilis, B. nobmanniae, B. prionota, B. sanguineopilosa and B. vermeulenii; Least Concern (LC) for B. lasioura, B. rantemarioensis and B. torajana; and Data Deficient (DD) for B. insueta. An identification key to Begonia in South and West Sulawesi (Sulawesi Selatan and Sulawesi Barat) is provided. © 2011 Trustees of the Royal Botanic Garden Edinburgh.published_or_final_versio
An isogeometric finite element formulation for phase transitions on deforming surfaces
This paper presents a general theory and isogeometric finite element
implementation for studying mass conserving phase transitions on deforming
surfaces. The mathematical problem is governed by two coupled fourth-order
nonlinear partial differential equations (PDEs) that live on an evolving
two-dimensional manifold. For the phase transitions, the PDE is the
Cahn-Hilliard equation for curved surfaces, which can be derived from surface
mass balance in the framework of irreversible thermodynamics. For the surface
deformation, the PDE is the (vector-valued) Kirchhoff-Love thin shell equation.
Both PDEs can be efficiently discretized using -continuous interpolations
without derivative degrees-of-freedom (dofs). Structured NURBS and unstructured
spline spaces with pointwise -continuity are utilized for these
interpolations. The resulting finite element formulation is discretized in time
by the generalized- scheme with adaptive time-stepping, and it is fully
linearized within a monolithic Newton-Raphson approach. A curvilinear surface
parameterization is used throughout the formulation to admit general surface
shapes and deformations. The behavior of the coupled system is illustrated by
several numerical examples exhibiting phase transitions on deforming spheres,
tori and double-tori.Comment: fixed typos, extended literature review, added clarifying notes to
the text, added supplementary movie file
The distribution of interstellar dust in CALIFA edge-on galaxies via oligochromatic radiative transfer fitting
We investigate the amount and spatial distribution of interstellar dust in
edge-on spiral galaxies, using detailed radiative transfer modeling of a
homogeneous sample of 12 galaxies selected from the CALIFA survey. Our
automated fitting routine, FitSKIRT, was first validated against artificial
data. This is done by simultaneously reproducing the SDSS -, -, - and
-band observations of a toy model in order to combine the information
present in the different bands. We show that this combined, oligochromatic
fitting, has clear advantages over standard monochromatic fitting especially
regarding constraints on the dust properties. We model all galaxies in our
sample using a three-component model, consisting of a double exponential disc
to describe the stellar and dust discs and using a S\'ersic profile to describe
the central bulge. The full model contains 19 free parameters, and we are able
to constrain all these parameters to a satisfactory level of accuracy without
human intervention or strong boundary conditions. Apart from two galaxies, the
entire sample can be accurately reproduced by our model. We find that the dust
disc is about 75% more extended but only half as high as the stellar disc. The
average face-on optical depth in the V-band is and the spread of
within our sample is quite substantial, which indicates that some spiral
galaxies are relatively opaque even when seen face-on.Comment: 18 pages, 6 figures, 4 tables, Accepted for publication in MNRA
Study and simulation results for video landmark acquisition and tracking technology (Vilat-2)
The results of several investigations and hardware developments which supported new technology for Earth feature recognition and classification are described. Data analysis techniques and procedures were developed for processing the Feature Identification and Location Experiment (FILE) data. This experiment was flown in November 1981, on the second Shuttle flight and a second instrument, designed for aircraft flights, was flown over the United States in 1981. Ground tests were performed to provide the basis for designing a more advanced version (four spectral bands) of the FILE which would be capable of classifying clouds and snow (and possibly ice) as distinct features, in addition to the features classified in the Shuttle experiment (two spectral bands). The Shuttle instrument classifies water, bare land, vegetation, and clouds/snow/ice (grouped)
Age, Growth, Relative Abundance, and Scuba Capture of a New or Recovering Spawning Population of Lake Sturgeon in the Lower Niagara River, New York
The objective of our study was to collect age, growth, and catch-per-unit-effort information from a new or recovering population of lake sturgeon Acipenser fulvescens in the lower Niagara River, New York. From July 1998 through August 2000, we captured 67 lake sturgeon by use of gill nets, baited setlines, and scuba diving. Active capture by scuba divers (1.50 fish/ h) was much more effective than passive capture with gill nets (0.07 fish/h) and setlines (0.06 fish/h). Eggs of Chinook salmon Oncorhynchus tshawytscha were more effective as setline bait than were alewives Alosa pseudoharengus, but neither bait differed in effectiveness from rainbow smelt Osmerus mordax. Ages of captured lake sturgeon ranged from 1 to 23 years; 47 of the 61 aged fish were younger than age 10. Strong relationships were found between weight, W, and length, L (W = 0.0000005 L3.5564: R2 = 0.977) and between L and age (L = 394.05.log e[age] + 248.77; R2 = 0.878). The lake sturgeon population in the lower Niagara River is probably small relative to its historic abundance. This naturally reproducing population should remain listed as threatened by New York State, and commercial and recreational fisheries should remain closed so that the population can rebuild adult numbers and reproductive potential
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