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Footprint-weighted tile approach for a spruce forest and a nearby patchy clearing using the ACASA model
The ACASA (Advanced Canopy-Atmosphere-Soil Algorithm) model, with a higher-order closure for tall vegetation, has already been successfully tested and validated for homogeneous spruce forests. The aim of this paper is to test the model using a footprint-weighted tile approach for a clearing with a heterogeneous structure of the underlying surface. The comparison with flux data shows a good agreement with a footprint-aggregated tile approach of the model. However, the results of a comparison with a tile approach on the basis of the mean land use classification of the clearing is not significantly different. It is assumed that the footprint model is not accurate enough to separate small-scale heterogeneities. All measured fluxes are corrected by forcing the energy balance closure of the test data either by maintaining the measured Bowen ratio or by the attribution of the residual depending on the fractions of sensible and latent heat flux to the buoyancy flux. The comparison with the model, in which the energy balance is closed, shows that the buoyancy correction for Bowen ratios > 1.5 better fits the measured data. For lower Bowen ratios, the correction probably lies between the two methods, but the amount of available data was too small to make a conclusion. With an assumption of similarity between water and carbon dioxide fluxes, no correction of the net ecosystem exchange is necessary for Bowen ratios > 1.5
The Rigidly Rotating Magnetosphere of Sigma Ori E
We attempt to characterize the observed variability of the magnetic
helium-strong star sigma Ori E in terms of a recently developed rigidly
rotating magnetosphere model. This model predicts the accumulation of
circumstellar plasma in two co-rotating clouds, situated in magnetohydrostatic
equilibrium at the intersection between magnetic and rotational equators. We
find that the model can reproduce well the periodic modulations observed in the
star's light curve, H alpha emission-line profile, and longitudinal field
strength, confirming that it furnishes an essentially correct, quantitative
description of the star's magnetically controlled circumstellar environment.Comment: 4 pages, 3 figures, accepted by Ap
Generation of HBsAg-reactive T- and B-cells following HBV vaccination in serological non-responders under hemodialysis treatment
Magnetic Rotator Winds and Keplerian Disks of Hot Stars
We consider rotating magnetic stars with winds and disks. We establish a
theorem that relates the angular velocity of a disk region with no meridional
motion to the angular velocity of the star. Also, we show that for a given
value of the magnetic field strength, if the rotation rate is too high or the
flow velocity into the shock boundary is too low, a Keplerian disk region will
not be formed. We develop a model for the formation of disks in magnetic
rotators through the processes of fill-up and diffusion into Keplerian orbits.
At the end of the fill-up stage the density of the disk increases significantly
and the magnetic force in the disk becomes negligible. We derive analytical
expressions for the inner and outer radii of Keplerian disks in terms of the
stellar rotation rate. A disk can form if the meridional component Bm of the
field at the stellar surface is larger than a minimum value. The radial extent
of the Keplerian region becomes larger for larger values of Bm and is largest
when Bm equals an optimal value. The strengths of the minimum fields required
for Keplerian disk formation in B-type stars varies from order 1G to 10G. In
O-type stars they must be of order 500G. Also, we suggest that the stellar
magnetic fields may be affected by rotationally driven meridional circulation
leading to some of the the observed variations of disks with time.Comment: 44 pages, 1 figure, accepted by Ap
New Perspectives on the X-ray Emission of HD 104237 and Other Nearby Herbig Ae/Be Stars from XMM-Newton and Chandra
We present new X-ray observations of the nearby Herbig Ae star HD 104237 (=
DX Cha) with XMM-Newton, whose objective is to clarify the origin of the
emission. Several X-ray emission lines are clearly visible in the CCD spectra,
including the high-temperature Fe K-alpha complex. The emission can be
accurately modeled as a multi-temperature thermal plasma with cool (kT < 1 keV)
and hot (kT > 3 keV) components. The presence of a hot component is compelling
evidence that the X-rays originate in magnetically confined plasma, either in
the Herbig star itself or in the corona of an as yet unseen late-type
companion. The X-ray temperatures and luminosity (log Lx = 30.5 ergs/s) are
within the range expected for a T Tauri companion, but high resolution Chandra
and HST images constrain the separation of a putative companion to less than 1
arcsec. We place these new results into broader context by comparing the X-ray
and bolometric luminosities of a sample of nearby Herbig stars with those of T
Tauri stars and classical main-sequence Be stars. We also test the predictions
of a model that attributes the X-ray emission of Herbig stars to magnetic
activity that is sustained by a shear-powered dynamo.Comment: To appear in ApJ (part 1); 43 pages, 8 figures, 5 table
Chandra Observations of Variable Embedded X-ray sources in Orion. Paper I: Resolving Orion Trapezium
We used the High Energy Transmission Grating Spectrometer (HETGS) onboard the
Chandra X-ray Observatory to perform two observations, separated by three
weeks, of the Orion Trapezium region. The zeroth order images on the Advanced
CCD Imaging Spectrometer (ACIS) provide spatial resolution of 0.5" and moderate
energy resolution. Within a 160"x140" region around the Orion Trapezium we
resolve 111 X-ray sources with luminosities between 7x10^{28} ergs/s and
2x10^{32} ergs/s. We do not detect any diffuse emission. Many sources appear
much more heavily absorbed, with N_H in the range of 10^22 to 10^23 cm^-2. The
main objective of this paper is to study the Orion Trapezium and its close
vicinity. Most spectra of the very early type members can be fit with a
two-temperature thermal spectrum with a soft component of kT ~ 0.8 keV and a
hard component of kT ~ 2 to 3 keV. We discuss these results in the context of
stellar wind models. We detect eight additional, mostly variable X-ray sources
in the close vicinity of the Trapezium. Five of these X-rays sources are
identified with proplyds and we argue that the X-ray emission originates from
class I, II and III protostars at the cores of the proplyds.Comment: 12 pages, 3 figures, accepted for publication in The Astrophysical
Journa
The view from above: the relevance of shared aerial drone videos for destination marketing
The use of drones to produce videos has generated a large amount of visually appealing footage of various destinations. They attract much attention, but there are issues that affect their production, and their relevance to destination marketing. This research examines YouTube meta-data and spatial overlay analysis of shared aerial drone videos from the United Kingdom (UK). The results suggest that shared aerial drone videos have some unique user-generated content (UGC) characteristics and their spatial distribution tend to favor more populated areas. Theoretical and practical implications for destination marketing are further discussed
Photoemission Spectroscopy and Atomic Force Microscopy Investigation of Vapor Phase Co-Deposited Silver/Poly(3-hexylthiophene) Composites
Nanocomposite matrices of silver/poly(3-hexylthiophene) (P3HT) were prepared
in ultrahigh vacuum through vapor-phase co-deposition. Change in
microstructure, chemical nature and electronic properties with increasing
filler (Ag) content were investigated using in-situ XPS and UPS, and ambient
AFM. At least two chemical binding states occur between Ag nanoparticles and
sulfur in P3HT at the immediate contact layer but no evidence of interaction
between Ag and carbon (in P3HT) was found. AFM images reveal a change in Ag
nanoparticles size with concentration which modifies the microstructure and the
average roughness of the surface. Under co-deposition, P3HT largely retains its
conjugated structures, which is evidenced by the similar XPS and UPS spectra to
those of P3HT films deposited on other substrates. We demonstrate here that the
magnitude of the barrier height for hole injection and the position of the
highest occupied band edge (HOB) with respect to the Fermi level of Ag can be
controlled and changed by adjusting the metal (Ag) content in the composite.
Furthermore, UPS reveals distinct features related to the C 2p (Sigma states)
in the 5-12 eV regions, indicating the presence of ordered P3HT which is
different from solution processed films.Comment: Scudier and Wei provided equal contributio
Single-cell clonal tracking of persistent T-cells in allogeneic hematopoietic stem cell transplantation
The critical balance between intended and adverse effects in allogeneic hematopoietic stem cell transplantation (alloHSCT) depends on the fate of individual donor T-cells. To this end, we tracked αβT-cell clonotypes during stem cell mobilization treatment with granulocyte-colony stimulating factor (G-CSF) in healthy donors and for six months during immune reconstitution after transfer to transplant recipients. More than 250 αβT-cell clonotypes were tracked from donor to recipient. These clonotypes consisted almost exclusively of CD8+ effector memory T cells (CD8TEM), which exhibited a different transcriptional signature with enhanced effector and cytotoxic functions compared to other CD8TEM. Importantly, these distinct and persisting clonotypes could already be delineated in the donor. We confirmed these phenotypes on the protein level and their potential for selection from the graft. Thus, we identified a transcriptional signature associated with persistence and expansion of donor T-cell clonotypes after alloHSCT that may be exploited for personalized graft manipulation strategies in future studies
Comparação da matéria orgânica e de outros atributos do solo entre plantações de Acacia mangium e Eucalyptus grandis
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