2,801 research outputs found
Assessment of Unmanned Aerial Systems and lidar for the Utility Vegetation Management of Electrical Distribution Rights-of-Ways
Utility Vegetation Management (UVM) is often the largest maintenance expense for many utilities. However, with advances in Unmanned Aerial Systems (UAS; or more commonly, “drones”) and lidar technologies, vegetation managers may be able to more rapidly and accurately identify vegetation threats to critical infrastructures. The goal of this study was to assess the utility of Geodetics’ UAS-lidar system for vegetation threat assessment for 1.6 km of a distribution electric circuit. We investigated factors which contribute to accurate tree crown detection and segmentation of trees from within an UAS-lidar derived point cloud, and the factors which contribute to accurate tree risk assessment. The study adapted the International Society of Arboriculture’s (ISA) tree risk assessment methodology to the application of remotely sensed tree inventory. We utilized the lidar detected and segmented tree crowns for tree risk analysis based upon each tree’s height, elevation, and location in relation to the electrical infrastructure. The individual tree detection and segmentation results show that our canopy type parameter and the routine used for field- and lidar-derived tree matching to have the largest effect on the classification agreement of field and lidar derived datasets. The Threat Detection classification also demonstrated a significant effect due to our canopy modeling parameter, where single canopy models possessed higher average Kappa agreement statistic and divided canopy models detected a larger number of threats on average. Ultimately, our best model was capable of the correct detection, segmentation, matching, and classification of half of the field trees which were determined to be vegetation threats
Mpemba effect in terms of mean first passage time
The Mpemba effect occurs when a system prepared at a hot temperature cools
down faster to the bath temperature than an identical system starting at a warm
temperature. We derive the condition for the Mpemba effect in the
small-diffusion limit of overdamped Langevin dynamics on a double-well
potential. Our results show the strong Mpemba effect occurs when the
probability of being in a well at initial and bath temperature match, which
agrees with experiments. We also derive the conditions for the weak Mpemba
effect and express the conditions for the effects in terms of mean first
passage time
Transcriptional profiling of colicin-induced cell death of Escherichia coli MG1655 identifies potential mechanisms by which bacteriocins promote bacterial diversity
We report the transcriptional response of Escherichia coli MG1655 to damage induced by colicins E3 and E9, bacteriocins that kill cells through inactivation of the ribosome and degradation of chromosomal DNA, respectively. Colicin E9 strongly induced the LexA-regulated SOS response, while colicin E3 elicited a broad response that included the induction of cold shock genes, symptomatic of translational arrest. Colicin E3 also increased the transcription of cryptic prophage genes and other laterally acquired mobile elements. The transcriptional responses to both these toxins suggest mechanisms that may promote genetic diversity in E. coli populations, pointing to a more general role for colicins in adaptive bacterial physiology than has hitherto been realized
Dijet Cross Section and Longitudinal Double Spin Asymmetry Measurements in Polarized Proton-proton Collisions at \sqrt{s}=200 GeV at STAR
These proceedings show the preliminary results of the dijet cross sections
and the dijet longitudinal double spin asymmetries A_LL in polarized
proton-proton collisions at \sqrt{s} = 200 GeV at the mid-rapidity |eta| < 0.8.
The integrated luminosity of 5.39 pb^{-1} collected during RHIC Run-6 was used
in the measurements. The preliminary results are presented as functions of the
dijet invariant mass M_jj. The dijet cross sections are in agreement with
next-to-leading-order pQCD predictions. The A_LL is compared with theoretical
predictions based on various parameterizations of polarized parton
distributions of the proton. Projected precision of data analyzed to date from
Run-9 are shown.Comment: 8 pages, 5 figures, Proceedings of the SPIN2010 conference (Juelich,
Germany, 2010
Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569
Photometric and spectroscopic analyses have shown that the Galactic bulge
cluster Terzan 5 hosts several populations with different metallicities and
ages that manifest as a double red horizontal branch (HB). A recent
investigation of the massive bulge cluster NGC 6569 revealed a similar, though
less extended, HB luminosity split, but little is known about the cluster's
detailed chemical composition. Therefore, we have used high-resolution spectra
from the Magellan-M2FS and VLT-FLAMES spectrographs to investigate the chemical
compositions and radial velocity distributions of red giant branch and HB stars
in NGC 6569. We found the cluster to have a mean heliocentric radial velocity
of -48.8 km/s (sigma = 5.3 km/s; 148 stars) and a mean [Fe/H] =-0.87 dex (19
stars), but the cluster's 0.05 dex [Fe/H] dispersion precludes a significant
metallicity spread. NGC 6569 exhibits light- and heavy-element distributions
that are common among old bulge/inner Galaxy globular clusters, including clear
(anti)correlations between [O/Fe], [Na/Fe], and [Al/Fe]. The light-element data
suggest that NGC 6569 may be composed of at least two distinct populations, and
the cluster's low mean [La/Eu] = -0.11 dex indicates significant pollution with
r-process material. We confirm that both HBs contain cluster members, but
metallicity and light-element variations are largely ruled out as sources for
the luminosity difference. However, He mass fraction differences as small as
delta Y ~ 0.02 cannot be ruled out and may be sufficient to reproduce the
double HB.Comment: 72 pages, 14 figures, 8 tables; published in The Astronomical
Journal; electronic versions of all tables are available in the published
versio
A Chemical Composition Survey of the Iron-Complex Globular Cluster NGC 6273 (M 19)
Recent observations have shown that a growing number of the most massive
Galactic globular clusters contain multiple populations of stars with different
[Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been
recognized as a member of this "iron-complex" cluster class, and we provide
here a chemical and kinematic analysis of > 300 red giant branch (RGB) and
asymptotic giant branch (AGB) member stars using high resolution spectra
obtained with the Magellan-M2FS and VLT-FLAMES instruments. Multiple lines of
evidence indicate that NGC 6273 possesses an intrinsic metallicity spread that
ranges from about [Fe/H] = -2 to -1 dex, and may include at least three
populations with different [Fe/H] values. The three populations identified here
contain separate first (Na/Al-poor) and second (Na/Al-rich) generation stars,
but a Mg-Al anti-correlation may only be present in stars with [Fe/H] > -1.65.
The strong correlation between [La/Eu] and [Fe/H] suggests that the s-process
must have dominated the heavy element enrichment at higher metallicities. A
small group of stars with low [alpha/Fe] is identified and may have been
accreted from a former surrounding field star population. The cluster's large
abundance variations are coupled with a complex, extended, and multimodal blue
horizontal branch (HB). The HB morphology and chemical abundances suggest that
NGC 6273 may have an origin that is similar to omega Cen and M 54.Comment: Accepted for Publication in The Astrophysical Journal; 50 pages; 18
figures; 8 tables; higher resolution figures are available upon request or in
the published journal articl
Risk of venous thromboembolism in hospitalised cancer patients in England—a cohort study
Background
Venous thromboembolism (VTE) is a well-recognised and life-threatening complication in patients with cancer. However, the precise risk of VTE in hospitalised cancer patients in England has not been previously reported.
Methods
We conducted a cohort study using linked Hospital Episodes Statistics and Office for National Statistics mortality data. We determined the risk of VTE separately for 24 cancer sites following first hospitalisation for cancer (index date) and how this varied by age, proximity from hospital admission, administration of chemotherapy and calendar time.
Results
Between 1998 and 2012, 3,558,660 patients were hospitalised for cancer. The cancer sites with the highest risk of VTE during initial hospitalisation for cancer were pancreatic (4.9 %), ovarian (4 %) and liver (3.8 %). The three cancer sites with the highest risk of first VTE event within 6 months from discharge were pancreatic (3.7 %), oesophagus (3 %) and stomach (2.8 %). For most cancers, the risk of VTE within 6 months from discharge was higher amongst patients who underwent chemotherapy compared to those who did not. The impact of age on risk of VTE varied considerably between cancer sites.
Conclusions
The risk of VTE amongst patients hospitalised for cancer varies greatly by cancer site, age, proximity from hospital admission, and chemotherapy administration.</p
The Nature of the Density Clump in the Fornax Dwarf Spheroidal Galaxy
We have imaged the recently discovered stellar overdensity located
approximately one core radius from the center of the Fornax dwarf spheroidal
galaxy using the Magellan Clay 6.5m telescope with the Magellan Instant Camera
(MagIC). Superb seeing conditions allowed us to probe the stellar populations
of this overdensity and of a control field within Fornax to a limiting
magnitude of R=26. The color-magnitude diagram of the overdensity field is
virtually identical to that of the control field with the exception of the
presence of a population arising from a very short (less than 300 Myr in
duration) burst of star formation 1.4 Gyr ago. Coleman et al. have argued that
this overdensity might be related to a shell structure in Fornax that was
created when Fornax captured a smaller galaxy. Our results are consistent with
this model, but we argue that the metallicity of this young component favors a
scenario in which the gas was part of Fornax itself.Comment: 24 pages including 8 figures and 3 tables. Accepted by Astronomical
Journa
Comparison of location, depth, quality and intensity of experimentally induced pain in six low back muscles
Introduction: The pattern of pain originating from experimentally induced low back pain appears diffuse. This may be because sensory information from low back muscles converges, sensory innervation extends over multiple vertebral levels, or people have difficulty accurately representing the painful location on standardized pain maps
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