3,714 research outputs found
Big Data for a Deep Problem: Exploring Natural Deep Eutectic Solvent (NADES) Properties through RDKIT and Data Analytics
https://tigerprints.clemson.edu/csrp/1014/thumbnail.jp
Structure of the outer layers of cool standard stars
Context: Among late-type red giants, an interesting change occurs in the
structure of the outer atmospheric layers as one moves to later spectral types
in the Hertzsprung-Russell diagram: a chromosphere is always present, but the
coronal emission diminishes and a cool massive wind steps in.
Aims: Where most studies have focussed on short-wavelength observations, this
article explores the influence of the chromosphere and the wind on
long-wavelength photometric measurements.
Methods: The observational spectral energy distributions are compared with
the theoretical predictions of the MARCS atmosphere models for a sample of 9 K-
and M-giants. The discrepancies found are explained using basic models for flux
emission originating from a chromosphere or an ionized wind.
Results: For 7 out of 9 sample stars, a clear flux excess is detected at
(sub)millimeter and/or centimeter wavelengths. The precise start of the excess
depends upon the star under consideration. The flux at wavelengths shorter than
about 1 mm is most likely dominated by an optically thick chromosphere, where
an optically thick ionized wind is the main flux contributor at longer
wavelengths.
Conclusions: Although the optical to mid-infrared spectrum of the studied K-
and M-giants is well represented by a radiative equilibrium atmospheric model,
the presence of a chromosphere and/or ionized stellar wind at higher altitudes
dominates the spectrum in the (sub)millimeter and centimeter wavelength ranges.
The presence of a flux excess also has implications on the role of these stars
as fiducial spectrophotometric calibrators in the (sub)millimeter and
centimeter wavelength range.Comment: 13 pages, 6 figures, 7 pages of online material, submitted to A&
A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455-282, WD0621-376, and WD2211-495
Using newly obtained high-resolution data () from the
\textit{Hubble Space Telescope}, and archival UV data from the \textit{Far
Ultraviolet Spectroscopic Explorer} we have conducted a detailed UV survey of
the three hot, metal-polluted white dwarfs WD0455-282, WD0621-376, and
WD2211-495. Using bespoke model atmospheres we measured , log
, and photospheric abundances for these stars. In conjunction with data from
Gaia we measured masses, radii, and gravitational redshift velocities for our
sample of objects. We compared the measured photospheric abundances with those
predicted by radiative levitation theory, and found that the observed Si
abundances in all three white dwarfs, and the observed Fe abundances in
WD0621-376 and WD2211-495, were larger than those predicted by an order of
magnitude. These findings imply not only an external origin for the metals, but
also ongoing accretion, as the metals not supported by radiative levitation
would sink on extremely short timescales. We measured the radial velocities of
several absorption features along the line of sight to the three objects in our
sample, allowing us to determine the velocities of the photospheric and
interstellar components along the line of sight for each star. Interestingly,
we made detections of circumstellar absorption along the line of sight to
WD0455-282 with three velocity components. To our knowledge, this is the first
such detection of multi-component circumstellar absorption along the line of
sight to a white dwarf.Comment: 19 pages, 23 figures, 8 tables. Accepted for publication in the
Monthly Notices of the Royal Astronomical Societ
The Dynamic Shift to Green Chemistry: Investigating the Spectral Behavior of Natural Deep Eutectic Solvents (NADES) and their Performance as MALDI-TOF Matrices
https://tigerprints.clemson.edu/csrp/1013/thumbnail.jp
Recoilless resonant neutrino capture and basics of neutrino oscillations
It is shown that the experiment on recoilless resonant emission and
absorption of , proposed recently by Raghavan, could have an
important impact on our understanding of the physics of neutrino oscillations.Comment: Additional information in the last chapte
Clone flow analysis for a theory inspired Neutrino Experiment planning
The presence of several clone solutions in the simultaneous measurement of
() has been widely discussed in literature. In this letter
we write the analytical formulae of the clones location in the
() plane as a function of the physical input pair
(). We show how the clones move with changing
. The "clone flow" can be significantly different if computed
(naively) from the oscillation probabilities or (exactly) from the
probabilities integrated over the neutrino flux and cross-section.
Using our complete computation we compare the clone flow of a set of possible
future neutrino experiments: the CERN SuperBeam, BetaBeam and Neutrino Factory
proposals. We show that the combination of these specific BetaBeam and
SuperBeam does not help in solving the degeneracies. On the contrary, the
combination of one of them with the Neutrino Factory Golden and Silver channel
can be used, from a theoretical point of view, to solve completely the
eightfold degeneracy.Comment: 23 pages, using epsfi
Biomass fuel use and indoor air pollution in homes in Malawi
Background: Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from biomass fuel in Malawian homes.
Methods: Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire.
Results: Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m3 (206 μg/m3). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m3 for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes.
Conclusions: Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health
Cyprus' image—a sun and sea destination—as a detrimental factor to seasonal fluctuations. Exploration into motivational factors for holidaying in Cyprus
Cyprus is established as a summer destination. To aid the destination in developing its winter season as well, this research uses a qualitative inductive approach to explore the tourists’ current image of the island and their motivations of visiting it. The research indicates that the current image, which essentially portrays Cyprus as a sun-and-sea destination is thought to dissuade tourists from perceiving the island as a year-round destination. Nonetheless, increasing the pull factors of the destination through the development of unique special interest products can help in extending the tourism season as well as broaden its narrow image
ArgoNeuT and the Neutrino-Argon Charged Current Quasi-Elastic Cross Section
ArgoNeuT, a Liquid Argon Time Projection Chamber in the NuMI beamline at
Fermilab, has recently collected thousands of neutrino and anti-neutrino events
between 0.1 and 10 GeV. The experiment will, among other things, measure the
cross section of the neutrino and anti-neutrino Charged Current Quasi-Elastic
interaction and analyze the vertex activity associated with such events. These
topics are discussed along with ArgoNeuT's automated reconstruction software,
currently capable of fully reconstructing the muon and finding the event vertex
in neutrino interactions.Comment: 6 pages, 4 figures, presented at the International Nuclear Physics
Conference, Vancouver, Canada, July 4-9, 2010, to be published in Journal of
Physics: Conference Series (JPCS
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