751 research outputs found
Astro2020 Science White Paper: Toward Finding Earth 2.0: Masses and Orbits of Small Planets with Extreme Radial Velocity Precision
Having discovered that Earth-sized planets are common, we are now embarking
on a journey to determine if Earth-like planets are also common. Finding
Earth-like planets is one of the most compelling endeavors of the 21st century
- leading us toward finally answering the question: Are we alone? To achieve
this forward-looking goal, we must determine the masses of the planets; the
sizes of the planets, by themselves, are not sufficient for the determination
of the bulk and atmospheric compositions. Masses, coupled with the radii, are
crucial constraints on the bulk composition and interior structure of the
planets and the composition of their atmospheres, including the search for
biosignatures. Precision radial velocity is the most viable technique for
providing essential mass and orbit information for spectroscopy of other
Earths. The development of high quality precision radial velocity instruments
coupled to the building of the large telescope facilities like TMT and GMT or
space-based platforms like EarthFinder can enable very high spectral resolution
observations with extremely precise radial velocities on minute timescales to
allow for the modeling and removal of radial velocity jitter. Over the next
decade, the legacy of exoplanet astrophysics can be cemented firmly as part of
humankind's quest in finding the next Earth - but only if we can measure the
masses and orbits of Earth-sized planets in habitable zone orbits around
Sun-like stars.Comment: Science White Paper Submitted to the Astro2020 Decadal Survey (35
co-signers in addition to co-authors
The Weiss conjecture on admissibility of observation operators for contraction semigroups
We prove the conjecture of George Weiss for contraction semigroups on Hilbert spaces, giving a characterization of infinite-time admissible observation functionals for a contraction semigroup, namely that such a functional C is infinite-time admissible if and only if there is an M > 0 such that parallel to IC(sI - A)(-1)parallel to less than or equal to M/root Re s for all s in the open right half-plane. Here A denotes the infinitesimal generator of the semigroup. The result provides a simultaneous generalization of several celebrated results from the theory of Hardy spaces involving Carleson measures and Hankel operators
Comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry for screening of organohalogenated compounds in cat hair
The coupling of comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry offers the best separation efficiency combined with accurate mass measurements over a wide mass range. The tremendous power of this screening tool is illustrated by trace qualitative screening analysis of organohalogenated compounds (OHCs) in pet cat hair. Tentative identification was supported by mass spectral database searches and elemental formula prediction from the experimentally determined accurate mass data. This screening approach resulted in the first tentative identification of pentabromoethylbenzene, decabromodiphenyl ethane, hexabromocyclododecane, trisbromoneopentyl alcohol, tris(2-chloroethyl) phosphate and tris(2-chloroisopropyl)phosphate in the South African indoor environment. A total of seventy-two OHCs were identified in the samples and include known flame retardants, such as polybrominated diphenyl ethers, and legacy contaminants such as polychlorinated biphenyls and organochlorine, organophosphorous and pyrethroid pesticides. The results obtained from cat hair indicate that these pets are exposed to complex mixtures of OHCs and the detection of these compounds suggests that non-invasive cat hair samples can be used to model indoor exposure with reference to external deposition of OHCs present in the air and dust surrounding people. Toddlers share the same environment as pet cats and therefore also the same health risks
The Development of an Open Source Intelligence Gathering Exercise for Teaching Information Security & Privacy
This research-in-progress paper describes the development of a pedagogical exercise on open source intelligence gathering (OSINT). Exercise materials will include instructions, teaching notes, assessment criteria, and a preconfigured virtual machine (VM), which acts as a local web server. The VM will host multiple websites containing vulnerable information pertinent to a fictitious target organization, in effect creating a capture the flag (CTF) scenario. The exercise will not only teach students how to find public information, but also help students realize the importance of protecting such information. While this exercise is primarily geared towards those pursuing a career in information security, the exercise is appropriate for all students as it shows how personal information could be used against them, as well as their organizations
The utilisation of health research in policy-making: Concepts, examples and methods of assessment
The importance of health research utilisation in policy-making, and of understanding the
mechanisms involved, is increasingly recognised. Recent reports calling for more resources to
improve health in developing countries, and global pressures for accountability, draw greater
attention to research-informed policy-making. Key utilisation issues have been described for at
least twenty years, but the growing focus on health research systems creates additional dimensions.
The utilisation of health research in policy-making should contribute to policies that may eventually
lead to desired outcomes, including health gains. In this article, exploration of these issues is
combined with a review of various forms of policy-making. When this is linked to analysis of
different types of health research, it assists in building a comprehensive account of the diverse
meanings of research utilisation.
Previous studies report methods and conceptual frameworks that have been applied, if with varying
degrees of success, to record utilisation in policy-making. These studies reveal various examples of
research impact within a general picture of underutilisation.
Factors potentially enhancing utilisation can be identified by exploration of: priority setting;
activities of the health research system at the interface between research and policy-making; and
the role of the recipients, or 'receptors', of health research. An interfaces and receptors model
provides a framework for analysis.
Recommendations about possible methods for assessing health research utilisation follow
identification of the purposes of such assessments. Our conclusion is that research utilisation can
be better understood, and enhanced, by developing assessment methods informed by conceptual
analysis and review of previous studies
Charging Ultrasmall Tunnel Junctions in Electromagnetic Environment
We have investigated the quantum admittance of an ultrasmall tunnel junction
with arbitrary tunneling strength under an electromagnetic environment. Using
the functional integral approach a close analytical expression of the quantum
admittance is derived for a general electromagnetic environment. We then
consider a specific controllable environment where a resistance is connected in
series with the tunneling junction, for which we derived the dc quantum
conductance from the zero frequency limit of the imaginary part of the quantum
admittance. For such electromagnetic environment the dc conductance has been
investigated in recent experiments, and our numerical results agree
quantitatively very well with the measurements. Our complete numerical results
for the entire range of junction conductance and electromagnetic environmental
conductance confirmed the few existing theoretical conclusions.Comment: 7 pages, 3 ps-figure
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