51 research outputs found
Performance of the ground-based total ozone network assessed using satellite data
Dobson and Brewer spectrophotometer and filter ozonometer data available from the World Ozone and Ultraviolet Data Centre (WOUDC) were compared with satellite total ozone measurements from TOMS (onboard Nimbus 7, Meteor 3, and Earth Probe satellites), OMI (AURA satellite) and GOME (ERS-2 satellite) instruments. Five characteristics of the difference with satellite data were calculated for each site and instrument type: the mean difference, the standard deviation of daily differences, the standard deviation of monthly differences, the amplitude of the seasonal component of the difference, and the range of annual values. All these characteristics were calculated for five 5-year-long bins and for each site separately for direct sun (DS) and zenith sky (ZS) ozone measurements. The main percentiles were estimated for the five characteristics of the difference and then used to establish criteria for “suspect” or “outlier” sites for each characteristic. About 61% of Dobson, 46% of Brewer, and 28% of filter stations located between 60°S and 60°N have no “suspect” or “outlier” characteristics. In nearly 90% of all cases, Dobson and Brewer sites demonstrated 5-year mean differences with satellites to be within ±3% (for DS observations). The seasonal median difference between all Brewer DS measurements at 25°–60°N and GOME and OMI overpasses remained within ±0.5% over a period of more than 10 years (...
The double-mode nature of the HADS star GSC 00144-03031 and the Petersen diagram of the class
The double--mode pulsation of GSC 00144-03031 has been detected when
searching for COROT targets. A very large dataset composed of 4722 photometric
measurements was collected at six observatories in Europe and America. There is
no hint of the excitation of additional modes (down to 0.6 mmag) and therefore
GSC 00144-03031 seems to be a pure double--mode pulsator, with a very short
fundamental radial mode (P=84 min). From Stromgren photometry and evolutionary
tracks it appears to be a Pop. I star with M=1.75 solar masses, located in the
middle of the instability strip, close to the Zero--Age Main Sequence. We also
discovered other new double--mode pulsators in the databases of large--scale
projects: OGLE BW2_V142, OGLE BW1_V207, ASAS3 094303-1707.3, ASAS3
000116-6037.0, NSVS 3234596 and NSVS 3324715. An observational Petersen diagram
is presented and explained by means of new models. A common sequence connecting
Pop. I stars from the shortest to the longest periods is proposed and the
spreads in the period ratios are ascribed to different metallicities (at the
shortest periods) and to different masses (at the longest ones). The paper is
based on data collected at S. Pedro Martir and Sierra Nevada Observatories and
on the contributions from several amateur astronomers.Comment: 9 pages, 5 pages, accepted for publication in Astronomy and
Astrophysic
Discovery and application of Frequency Ratio Method to the new multiperiodic gamma Dor star HD 218427
gamma Dor-type oscillations have been discovered in the star HD218427 through
simultaneous uvby photometric observations carried out in the year 2003. A few
Hbeta-Crawford measurements were also collected for calibration purposes which
place this star well-located inside the gamma Dor instability region.
Deficiency in metal content, similar to other well-defined gamma Dor stars, is
found in HD218427 and the possibility of a lambda Boo nature is discussed.
Frequency analysis was carried out for different filters, the combined "vby"
filter was also used and five frequencies were found as significant with
periods ranging between 0.3 and 0.8 days. The recently developed Frequency
Ratio Method is used in order to perform an identification of the excited
modes. The results are consistent with an l=2 identification for all the modes
and high radial quantum numbers (n~40) for the three main observed
periodicities. The possibility of multiplet structures is also discussed.
However, no consistency is found when the Time-Dependent Convection treatment
is used for modes discrimination. The disagreement can be due to the large
rotation velocity taking place in HD218427 and, consequently, the significant
coupling between the modes.Comment: 10 pages, 3 figures. Accepted by A&
Internet of Things for Sustainable Human Health
The sustainable health IoT has the strong potential to bring tremendous improvements in human health and well-being through sensing, and monitoring of health impacts across the whole spectrum of climate change. The sustainable health IoT enables development of a systems approach in the area of human health and ecosystem. It allows integration of broader health sub-areas in a bigger archetype for improving sustainability in health in the realm of social, economic, and environmental sectors. This integration provides a powerful health IoT framework for sustainable health and community goals in the wake of changing climate. In this chapter, a detailed description of climate-related health impacts on human health is provided. The sensing, communications, and monitoring technologies are discussed. The impact of key environmental and human health factors on the development of new IoT technologies also analyzed
On-the-Fly ab initio Semiclassical Evaluation of Electronic Coherences in Polyatomic Molecules Reveals a Simple Mechanism of Decoherence
Irradiation of a molecular system by an intense laser field can trigger dynamics of both electronic and nuclear subsystems. The lighter electrons usually move on much faster, attosecond timescale but the slow nuclear rearrangement damps ultrafast electronic oscillations, leading to the decoherence of the electronic dynamics within a few femtoseconds. We show that a simple, single-trajectory semiclassical scheme can evaluate the electronic coherence time in polyatomic molecules accurately by demonstrating an excellent agreement with full-dimensional quantum calculations. In contrast to numerical quantum methods, the semiclassical one reveals the physical mechanism of decoherence beyond the general blame on nuclear motion. In the propiolic acid, the rate of decoherence and the large deviation from the static frequency of electronic oscillations are quantitatively described with just two semiclassical parameters-the phase space distance and signed area between the trajectories moving on two electronic surfaces. Because it evaluates the electronic structure on the fly, the semiclassical technique avoids the "curse of dimensionality" and should be useful for preselecting molecules for experimental studies
Contaminant transport in the host rock. Numerical modelling and laboratory experiments.
Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi
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