2,699 research outputs found
Lightning location system supervising Swedish power transmission network
For electric utilities, the ability to prevent or minimize lightning damage on personnel and power systems is of great importance. Therefore, the Swedish State Power Board, has been using data since 1983 from a nationwide lightning location system (LLS) for accurately locating lightning ground strikes. Lightning data is distributed and presented on color graphic displays at regional power network control centers as well as at the national power system control center for optimal data use. The main objectives for use of LLS data are: supervising the power system for optimal and safe use of the transmission and generating capacity during periods of thunderstorms; warning service to maintenance and service crews at power line and substations to end operations hazardous when lightning; rapid positioning of emergency crews to locate network damage at areas of detected lightning; and post analysis of power outages and transmission faults in relation to lightning, using archived lightning data for determination of appropriate design and insulation levels of equipment. Staff have found LLS data useful and economically justified since the availability of power system has increased as well as level of personnel safety
The Planck SZ Cluster Catalog: Expected X-ray Properties
Surveys based on the Sunyaev-Zel'dovich (SZ) effect provide a fresh view of
the galaxy cluster population, one that is complementary to X-ray surveys. To
better understand the relation between these two kinds of survey, we construct
an empirical cluster model using scaling relations constrained by current X-ray
and SZ data. We apply our model to predict the X-ray properties of the Planck
SZ Cluster Catalog (PCC) and compare them to existing X-ray cluster catalogs.
We find that Planck should significantly extend the depth of the previous
all-sky cluster survey, performed in the early 1990s by the ROSAT satellite,
and should be particularly effective at finding hot, massive clusters (T > 6
keV) out to redshift unity. These are rare objects, and our findings suggest
that Planck could increase the observational sample at z > 0.6 by an order of
magnitude. This would open the way for detailed studies of massive clusters out
to these higher redshifts. Specifically, we find that the majority of
newly-detected Planck clusters should have X-ray fluxes 10^{-13} ergs/s/cm^2 <
f_X[0.5-2 keV] < 10^{-12} ergs/s/cm^2, i.e., distributed over the decade in
flux just below the ROSAT All Sky Survey limit. This is sufficiently bright for
extensive X-ray follow-up campaigns. Once Planck finds these objects,
XMM-Newton and \textit{Chandra} could measure temperatures to 10% for a sample
of ~ 100 clusters in the range 0.5 < z < 1, a valuable increase in the number
of massive clusters studied over this range.Comment: 8 pages, 7 figures submitted to A&A; accepted 29 May 201
Scalp cooling with adjuvant/neoadjuvant chemotherapy for breast cancer and the risk of scalp metastases: systematic review and meta-analysis.
PurposeThe risk of scalp metastases in patients using scalp cooling for preservation of hair during chemotherapy has been a concern but is poorly described.MethodsA systematic review and meta-analysis of longitudinal studies was undertaken to evaluate the effect of scalp cooling versus no scalp cooling on the risk of scalp metastasis in patients treated for breast cancer with chemotherapy. Electronic databases, journal specific, and hand searches of articles identified were searched. Patients were matched based on disease, treatment, lack of metastatic disease, and sex.ResultsA total of 24 full-text articles were identified for review. Of these articles, ten quantified the incidence of scalp metastasis with scalp cooling over time. For scalp cooling, 1959 patients were evaluated over an estimated mean time frame of 43.1 months. For no scalp cooling, 1238 patients were evaluated over an estimated mean time frame of 87.4 months. The incidence rate of scalp metastasis in the scalp cooling group versus the no scalp cooling group was 0.61% (95% CI 0.32-1.1%) versus 0.41% (95% CI 0.13-0.94%); P = 0.43.ConclusionThe incidence of scalp metastases was low regardless of scalp cooling. This analysis suggests that scalp cooling does not increase the incidence of scalp metastases
An SZ/X-ray galaxy cluster model and the X-ray follow-up of the Planck clusters
Sunyaev-Zel'dovich (SZ) cluster surveys will become an important cosmological
tool over next few years, and it will be essential to relate these new surveys
to cluster surveys in other wavebands. We present an empirical model of cluster
SZ and X-ray observables constructed to address this question and to motivate,
dimension and guide X-ray follow-up of SZ surveys. As an example application of
the model, we discuss potential XMM-Newton follow-up of Planck clusters.Comment: 4 pages, 5 figures. To appear in the proceedings of the XXXXIIIrd
Rencontres de Morion
Ambipolar charge injection and transport in a single pentacene monolayer island
Electrons and holes are locally injected in a single pentacene monolayer
island. The two-dimensional distribution and concentration of the injected
carriers are measured by electrical force microscopy. In crystalline monolayer
islands, both carriers are delocalized over the whole island. On disordered
monolayer, carriers stay localized at their injection point. These results
provide insight into the electronic properties, at the nanometer scale, of
organic monolayers governing performances of organic transistors and molecular
devices.Comment: To be published in Nano Letter
Assessment of Satellite Radiometry in the Visible Domain
Marine reflectance and chlorophyll-a concentration are listed among the Essential Climate Variables by the Global Climate Observing System. To contribute to climate research, the satellite ocean color data records resulting from successive missions need to be consistent and well characterized in terms of uncertainties. This chapter reviews various approaches that can be used for the assessment of satellite ocean color data. Good practices for validating satellite products with in situ data and the current status of validation results are illustrated. Model-based approaches and inter-comparison techniques can also contribute to characterize some components of the uncertainty budget, while time series analysis can detect issues with the instrument radiometric characterization and calibration. Satellite data from different missions should also provide a consistent picture in scales of variability, including seasonal and interannual signals. Eventually, the various assessment approaches should be combined to create a fully characterized climate data record from satellite ocean color
Semi-classical Green kernel asymptotics for the Dirac operator
We consider a semi-classical Dirac operator in arbitrary spatial dimensions
with a smooth potential whose partial derivatives of any order are bounded by
suitable constants. We prove that the distribution kernel of the inverse
operator evaluated at two distinct points fulfilling a certain hypothesis can
be represented as the product of an exponentially decaying factor involving an
associated Agmon distance and some amplitude admitting a complete asymptotic
expansion in powers of the semi-classical parameter. Moreover, we find an
explicit formula for the leading term in that expansion.Comment: 46 page
- …