8,582 research outputs found
Health Research Participants' Preferences for Receiving Research Results
BACKGROUND: Participants in health research studies typically express interest in receiving results from the studies in which they participate. However, participantsâ preferences and experiences related to receiving results are not well understood. In general, existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. METHODS: The present study used an online survey to explore attitudes and experiences of registrants in ResearchMatch, a large database of past, present, and potential health research participants. Survey respondents provided information related to whether or not they received research results from studies in which they participated, the methods used to communicate results, their satisfaction with results, and when and how they would like to receive research results from future studies. 70,699 ResearchMatch registrants were notified of the studyâs topic. Of the 5,207 registrants who requested full information about the study, 3,381 respondents completed the survey. RESULTS: Approximately 33% of respondents with previous health research participation reported receiving results. Approximately half of respondents with previous research participation reported no opportunity to request results. However, almost all respondents said researchers should always or sometimes offer results to participants. Respondents expressed particular interest in results related to their (or a loved one's) health, as well as information about studiesâ purposes and any medical advances based on the results. In general, respondentsâ most preferred dissemination methods for results were email and website postings. The least desirable dissemination methods for results included Twitter, conference calls, and text messages. Across all results, we compare the responses of respondents with and without previous research participation experience, and those who have worked in research organizations vs. those who have not. Compared to respondents who have previous participation experience, a greater proportion of respondents with no participation experience indicated that results should always be shared with participants. Likewise, respondents with no participation experience placed higher importance on the receipt of each type of results information included in the survey. CONCLUSIONS: We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participantsâ preferences for receiving results. The studyâs findings highlight the potential for inconsistency between respondentsâ expressed preferences to receive specific types of results via specific methods and researchersâ unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participantsâ preferences for receiving research results
Strategic Network Formation with Attack and Immunization
Strategic network formation arises where agents receive benefit from
connections to other agents, but also incur costs for forming links. We
consider a new network formation game that incorporates an adversarial attack,
as well as immunization against attack. An agent's benefit is the expected size
of her connected component post-attack, and agents may also choose to immunize
themselves from attack at some additional cost. Our framework is a stylized
model of settings where reachability rather than centrality is the primary
concern and vertices vulnerable to attacks may reduce risk via costly measures.
In the reachability benefit model without attack or immunization, the set of
equilibria is the empty graph and any tree. The introduction of attack and
immunization changes the game dramatically; new equilibrium topologies emerge,
some more sparse and some more dense than trees. We show that, under a mild
assumption on the adversary, every equilibrium network with agents contains
at most edges for . So despite permitting topologies denser
than trees, the amount of overbuilding is limited. We also show that attack and
immunization don't significantly erode social welfare: every non-trivial
equilibrium with respect to several adversaries has welfare at least as that of
any equilibrium in the attack-free model.
We complement our theory with simulations demonstrating fast convergence of a
new bounded rationality dynamic which generalizes linkstable best response but
is considerably more powerful in our game. The simulations further elucidate
the wide variety of asymmetric equilibria and demonstrate topological
consequences of the dynamics e.g. heavy-tailed degree distributions. Finally,
we report on a behavioral experiment on our game with over 100 participants,
where despite the complexity of the game, the resulting network was
surprisingly close to equilibrium.Comment: The short version of this paper appears in the proceedings of WINE-1
Applying black hole perturbation theory to numerically generated spacetimes
Nonspherical perturbation theory has been necessary to understand the meaning
of radiation in spacetimes generated through fully nonlinear numerical
relativity. Recently, perturbation techniques have been found to be successful
for the time evolution of initial data found by nonlinear methods. Anticipating
that such an approach will prove useful in a variety of problems, we give here
both the practical steps, and a discussion of the underlying theory, for taking
numerically generated data on an initial hypersurface as initial value data and
extracting data that can be considered to be nonspherical perturbations.Comment: 14 pages, revtex3.0, 5 figure
Head-on collisions of black holes: the particle limit
We compute gravitational radiation waveforms, spectra and energies for a
point particle of mass falling from rest at radius into a
Schwarzschild hole of mass . This radiation is found to lowest order in
with the use of a Laplace transform. In contrast with numerical
relativity results for head-on collisions of equal-mass holes, the radiated
energy is found not to be a monotonically increasing function of initial
separation; there is a local radiated-energy maximum at . The
present results, along with results for infall from infinity, provide a
complete catalog of waveforms and spectra for particle infall. We give a
representative sample from that catalog and an interesting observation: Unlike
the simple spectra for other head-on collisions (either of particle and hole,
or of equal mass holes) the spectra for show a series of
evenly spaced bumps. A simple explanation is given for this. Lastly, our energy
vs. results are compared with approximation methods used elsewhere, for
small and for large initial separation.Comment: 15 pages, REVTeX, 25 figure
Radiation recoil from highly distorted black holes
We present results from numerical evolutions of single black holes distorted
by axisymmetric, but equatorially asymmetric, gravitational (Brill) waves. Net
radiated energies, apparent horizon embeddings, and recoil velocities are shown
for a range of Brill wave parameters, including both even and odd parity
distortions of Schwarzschild black holes. We find that a wave packet initially
concentrated on the black hole throat, a likely model also for highly
asymmetric stellar collapse and late stage binary mergers, can generate a
maximum recoil velocity of about 150 (23) km/sec for even (odd) parity
perturbations, significantly less than that required to eject black holes from
galactic cores.Comment: 15 pages, 8 figure
On the Discovery of the GZK Cut-off
The recent claim of the '5 sigma' observation of the Greisen and Zatzepin and
Kuzmin cut-off by the HiRes group based on their nine years data is a
significant step toward the eventual solution of the one of the most intriguing
questions which has been present in physics for more than forty years. However
the word 'significance' is used in the mentioned paper in the sense which is
not quite obvious. In the present paper we persuade that this claim is a little
premature.Comment: 10 page
Head--on Collision of Two Unequal Mass Black Holes
We present results from the first fully nonlinear numerical calculations of
the head--on collision of two unequal mass black holes. Selected waveforms of
the most dominant l=2, 3 and 4 quasinormal modes are shown, as are the total
radiated energies and recoil velocities for a range of mass ratios and initial
separations. Our results validate the close and distant separation limit
perturbation studies, and suggest that the head--on collision scenario is not
likely to produce an astrophysically significant recoil effect.Comment: 5 pages, 3 figure
Cryogenic and room temperature strength of sapphire jointed by hydroxide-catalysis bonding
Hydroxide-catalysis bonding is a precision technique used for jointing components in opto-mechanical systems and has been implemented in the construction of quasi-monolithic silica suspensions in gravitational wave detectors. Future detectors are likely to operate at cryogenic temperatures which will lead to a change in test mass and suspension material. One candidate material is mono-crystalline sapphire. Here results are presented showing the influence of various bonding solutions on the strength of the hydroxide-catalysis bonds formed between sapphire samples, measured both at room temperature and at 77 K, and it is demonstrated that sodium silicate solution is the most promising in terms of strength, producing bonds with a mean strength of 63 MPa. In addition the results show that the strengths of bonds were undiminished when tested at cryogenic temperatures
Finding Distant Galactic H Ii Regions
The WISE Catalog of Galactic H ii Regions contains ~2000 H ii region candidates lacking ionized gas spectroscopic observations. All candidates have the characteristic H ii region mid-infrared morphology of WISE 12 emission surrounding 22 emission, and additionally have detected radio continuum emission. We here report Green Bank Telescope hydrogen radio recombination line and radio continuum detections in the X-band (9 GHz; 3 cm) of 302 WISE H ii region candidates (out of 324 targets observed) in the zone , Here we extend the sky coverage of our H ii region Discovery Survey, which now contains nearly 800 H ii regions distributed across the entire northern sky. We provide LSR velocities for the 302 detections and kinematic distances for 131 of these. Of the 302 new detections, 5 have coordinates consistent with the Outer ScutumâCentaurus Arm (OSC), the most distant molecular spiral arm of the Milky Way. Due to the Galactic warp, these nebulae are found at Galactic latitudes \u3e1° in the first Galactic quadrant, and therefore were missed in previous surveys of the Galactic plane. One additional region has a longitude and velocity consistent with the OSC but lies at a negative Galactic latitude (G039.183â01.422; â54.9 ). With Heliocentric distances \u3e22 kpc and Galactocentric distances \u3e16 kpc, the OSC H ii regions are the most distant known in the Galaxy. We detect an additional three H ii regions near whose LSR velocities place them at Galactocentric radii \u3e19 kpc. If their distances are correct, these nebulae may represent the limit to Galactic massive star formation
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