3,846 research outputs found
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The First Supernova Explosions: Energetics, Feedback, And Chemical Enrichment
We perform three-dimensional smoothed particle hydrodynamics simulations in a realistic cosmological setting to investigate the expansion, feedback, and chemical enrichment properties of a 200M(circle dot) pair-instability supernova in the high-redshift universe. We find that the SN remnant propagates for a Hubble time at z similar or equal to 20 to a final mass-weighted mean shock radius of 2.5 kpc (proper), roughly half the size of the H II region, and in this process sweeps up a total gas mass of 2: 5; 10(5) M-circle dot. The morphology of the shock becomes highly anisotropic once it leaves the host halo and encounters filaments and neighboring minihalos, while the bulk of the shock propagates into the voids of the intergalactic medium. The SN entirely disrupts the host halo and terminates further star formation for at least 200 Myr, while in our specific case it exerts positive mechanical feedback on neighboring minihalos by shock-compressing their cores. In contrast, we do not observe secondary star formation in the dense shell via gravitational fragmentation, due to the previous photoheating by the progenitor star. We find that cooling by metal lines is unimportant for the entire evolution of the SN remnant, while the metal-enriched, interior bubble expands adiabatically into the cavities created by the shock, and ultimately into the voids with a maximum extent similar to the final mass-weighted mean shock radius. Finally, we conclude that dark matter halos of at least M-vir greater than or similar to 10(8) M-circle dot must be assembled to recollect all components of the swept-up gas.Astronom
Relaxed Bell inequalities and Kochen-Specker theorems
The combination of various physically plausible properties, such as no
signaling, determinism, and experimental free will, is known to be incompatible
with quantum correlations. Hence, these properties must be individually or
jointly relaxed in any model of such correlations. The necessary degrees of
relaxation are quantified here, via natural distance and information-theoretic
measures. This allows quantitative comparisons between different models in
terms of the resources, such as the number of bits, of randomness,
communication, and/or correlation, that they require. For example, measurement
dependence is a relatively strong resource for modeling singlet state
correlations, with only 1/15 of one bit of correlation required between
measurement settings and the underlying variable. It is shown how various
'relaxed' Bell inequalities may be obtained, which precisely specify the
complementary degrees of relaxation required to model any given violation of a
standard Bell inequality. The robustness of a class of Kochen-Specker theorems,
to relaxation of measurement independence, is also investigated. It is shown
that a theorem of Mermin remains valid unless measurement independence is
relaxed by 1/3. The Conway-Kochen 'free will' theorem and a result of Hardy are
less robust, failing if measurement independence is relaxed by only 6.5% and
4.5%, respectively. An appendix shows the existence of an outcome independent
model is equivalent to the existence of a deterministic model.Comment: 19 pages (including 3 appendices); v3: minor clarifications, to
appear in PR
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Investigating the Role of Social Return on the Understanding of Craft Brewery Visitors in British Columbia, Canada
Contributing to the Conference Theme: The role of social media in the development of Canada as a destination has been widely discussed locally, regionally, provincially, and federally. This research examines the role of using social media using a newly developed mechanism by which to consider how the use of social media relates to social involvement, memories, loyalty, place attachment, and authenticity. The context for this research is craft brewery tourism, one of the fastest growing aspects of tourism in many provinces. This abstract directly relates to multiple themes and sub-themes of the conference, including âVisitor experience design and measurement,â âMarketing and place promotion strategies and techniques,â and âConsumer demand for authentic places and experiences.
The Bulk Motion of Flat Edge-On Galaxies Based on 2MASS Photometry
We report the results of applying the 2MASS Tully-Fisher (TF) relations to
study the galaxy bulk flows. For 1141 all-sky distributed flat RFGC galaxies we
construct J, H, K_s TF relations and find that Kron magnitudes show
the smallest dispersion on the TF diagram. For the sample of 971 RFGC galaxies
with V_{3K} < 18000 km/s we find a dispersion and an
amplitude of bulk flow V= 199 +/-61 km/s, directed towards l=301 degr +/-18
degr, b=-2 degr +/-15 degr. Our determination of low-amplitude coherent flow is
in good agreement with a set of recent data derived from EFAR, PSCz, SCI/SCII
samples. The resultant two- dimensional smoothed peculiar velocity field traces
well the large-scale density variations in the galaxy distributions. The
regions of large positive peculiar velocities lie in the direction of the Great
Attractor and Shapley concentration. A significant negative peculiar velocity
is seen in the direction of Bootes and in the direction of the Local void. A
small positive peculiar velocity (100 -- 150 km/s) is seen towards the
Pisces-Perseus supercluster, as well as the Hercules - Coma - Corona Borealis
supercluster regions.Comment: 10 pages, 5 figures. A&A/2003/3582 accepted 15.05.200
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Understanding the Impacts of Festivals on Resident Attendees Before and During COVID-19: A First Look at the Vancouver Queer Film Festival
Although festivals and events have been identified as a growth segment within tourism, smaller cultural festivals have received much less attention. These smaller cultural festivals aim to bring cultural contributions and increased well-being to attendees and the host community in addition to their economic value. More specifically, queer film festivals have increased in number and size within the last decade and have an important history and purpose within the LGBT2Q+ community. As such, the current study investigated the attendees of the 2019 & 2020 Vancouver Queer Film Festival (VQFF), Western Canadaâs largest queer film festival. The survey instrument asked attendees questions about subjective well-being, cultural/educational impacts, community benefits, future programming, and demographics. Preliminary results comparing demographic, behavioural, perceived benefit, and outcome characteristics between the 2019 in-person version and the 2020 virtual pandemic version of VQFF are discussed. Industry and academic implications and areas for future study are also considered
Optical Spectroscopic Survey of High-latitude WISE-selected Sources
We report on the results of an optical spectroscopic survey at high Galactic latitude (|b| â„ 30°) of a sample of WISE-selected targets, grouped by WISE W1 (λ_eff = 3.4 ÎŒm) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30 ± 0.02 galaxies arcminâ2 with a median redshift of z = 0.33 ± 0.01 for the sample with W1 â„ 120 ÎŒJy. The foreground stellar densities in our survey range from 0.23 ± 0.07 arcminâ2 to 1.1 ± 0.1 arcminâ2 for the same sample. We obtained spectra that produced science grade redshifts for â„90% of our targets for sources with W1 flux â„120 ÎŒJy that also had an i-band flux gsim 18 ÎŒJy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies
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