44 research outputs found
850 μm Observations of the 11 July 1991 Total Solar Eclipse
We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimeter Observatory. The 850 μm limb is extended 3380±140 km above the visible limb, and there is a 10% brightening at the extreme limb. The measured limb height agrees with previous work at shorter and longer wavelengths. The run of limb heights with wavelength is well fit by a single electron density scale height. We argue that there is no need to invoke spicule geometry to explain the observations
850 μm Observations of the 11 July 1991 Total Solar Eclipse
We present observations of the 11 July 1991 total solar eclipse made from the Caltech Submillimeter Observatory. The 850 μm limb is extended 3380±140 km above the visible limb, and there is a 10% brightening at the extreme limb. The measured limb height agrees with previous work at shorter and longer wavelengths. The run of limb heights with wavelength is well fit by a single electron density scale height. We argue that there is no need to invoke spicule geometry to explain the observations
Tomographic 3D-Modeling of the Solar Corona with FASR
The "Frequency-Agile Solar Radiotelescope" (FASR) litteraly opens up a new
dimension in addition to the 3D Euclidian geometry: the frequency dimension.
The 3D geometry is degenerated to 2D in all images from astronomical
telescopes, but the additional frequency dimension allows us to retrieve the
missing third dimension by means of physical modeling. We call this type of 3D
reconstruction "Frequency Tomography". In this study we simulate a realistic 3D
model of an active region, composed of 500 coronal loops with the 3D geometry
[x(s),y(s),z(s)] constrained by magnetic field extrapolations and the physical
parameters of the density n_e(s) and temperature T_e(s) given by hydrostatic
solutions. We simulate a series of 20 radio images in a frequency range of
f=0.1-10 GHz, anticipating the capabilities of FASR, and investigate what
physical information can be retrieved from such a dataset. We discuss also
forward-modeling of the chromospheric and Quiet Sun density and temperature
structure, another primary goal of future FASR science.Comment: 10 Figure
Display of probability densities for data from a continuous distribution
Based on cumulative distribution functions, Fourier series expansion and
Kolmogorov tests, we present a simple method to display probability densities
for data drawn from a continuous distribution. It is often more efficient than
using histograms.Comment: 5 pages, 4 figures, presented at Computer Simulation Studies XXIV,
Athens, GA, 201
Explaining Andean Potato Weevils in Relation to Local and Landscape Features: A Facilitated Ecoinformatics Approach
BACKGROUND: Pest impact on an agricultural field is jointly influenced by local and landscape features. Rarely, however, are these features studied together. The present study applies a "facilitated ecoinformatics" approach to jointly screen many local and landscape features of suspected importance to Andean potato weevils (Premnotrypes spp.), the most serious pests of potatoes in the high Andes. METHODOLOGY/PRINCIPAL FINDINGS: We generated a comprehensive list of predictors of weevil damage, including both local and landscape features deemed important by farmers and researchers. To test their importance, we assembled an observational dataset measuring these features across 138 randomly-selected potato fields in Huancavelica, Peru. Data for local features were generated primarily by participating farmers who were trained to maintain records of their management operations. An information theoretic approach to modeling the data resulted in 131,071 models, the best of which explained 40.2-46.4% of the observed variance in infestations. The best model considering both local and landscape features strongly outperformed the best models considering them in isolation. Multi-model inferences confirmed many, but not all of the expected patterns, and suggested gaps in local knowledge for Andean potato weevils. The most important predictors were the field's perimeter-to-area ratio, the number of nearby potato storage units, the amount of potatoes planted in close proximity to the field, and the number of insecticide treatments made early in the season. CONCLUSIONS/SIGNIFICANCE: Results underscored the need to refine the timing of insecticide applications and to explore adjustments in potato hilling as potential control tactics for Andean weevils. We believe our study illustrates the potential of ecoinformatics research to help streamline IPM learning in agricultural learning collaboratives
Measurement of the Generalized Polarizabilities of the Proton in Virtual Scattering at Q2=0.92 and 1.76 GeV2: I. Low Energy Expansion Analysis
Virtual Compton Scattering is studied at the Thomas Jefferson National
Accelerator Facility at low Center-of-Mass energies, below pion threshold.
Following the Low Energy Theorem for the process, we obtain
values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum
transfer squared Q2=0.92 and 1.76 GeV2.Comment: 4 pages, 2 figures, to be submitted to PRL. Figs 1 and 2, lettering
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A ‘VISUAL’ APPROACH TO MENANDER - (A.K.) Petrides Menander, New Comedy and the Visual. Pp. xii + 322, ills. Cambridge: Cambridge University Press, 2014. Cased, £65, US$99. ISBN: 978-1-107-06843-8.
High-energy X-rays and gamma-rays from solar flares were discovered just over
fifty years ago. Since that time, the standard for the interpretation of
spatially integrated flare X-ray spectra at energies above several tens of keV
has been the collisional thick-target model. After the launch of the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in early 2002, X-ray
spectra and images have been of sufficient quality to allow a greater focus on
the energetic electrons responsible for the X-ray emission, including their
origin and their interactions with the flare plasma and magnetic field. The
result has been new insights into the flaring process, as well as more
quantitative models for both electron acceleration and propagation, and for the
flare environment with which the electrons interact. In this article we review
our current understanding of electron acceleration, energy loss, and
propagation in flares. Implications of these new results for the collisional
thick-target model, for general flare models, and for future flare studies are
discussed.Comment: This is an article from a monograph on the physics of solar flares,
inspired by RHESSI observations. The individual articles are to appear in
Space Science Reviews (2011
Bases conceituais para a aplicação de biomonitoramento em programas de avaliação da qualidade da água de rios
Hospital Governance and Quality of Care: A Critical Review of Transitional Roles
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68899/2/10.1177_002570879305000402.pd