1,172 research outputs found
Nesting Substrate Preference and Breeding of Common Terns (Sterna hirundo) and Black Skimmers (Rynchops niger) on the Hampton Roads Bridge-Tunnel
The Beilinson Equivalence for Differential Operators and Lie Algebroids
Let D be the ring of differential operators on a smooth irreducible affine
variety X over the complex numbers; or, more generally, the enveloping algebra
of any locally free Lie algebroid on X. The category of finitely-generated
graded modules of the Rees algebra D has a natural quotient category qgr(D)
which imitates the category of modules on Proj of a graded commutative ring. We
show that the derived category D^b(qgr(D)) is equivalent to the derived
category of finitely-generated modules of a sheaf of algebras E on X which is
coherent over X. This generalizes the usual Beilinson equivalence for
projective space, and also the Beilinson equivalence for differential operators
on a smooth curve used by Ben-Zvi and Nevins to describe the moduli space of
left ideals in D
Learning to Create Jazz Melodies Using Deep Belief Nets
We describe an unsupervised learning technique to facilitate automated creation of jazz melodic improvisation over chord sequences. Specifically we demonstrate training an artificial improvisation algorithm based on unsupervised learning using deep belief nets, a form of probabilistic neural network based on restricted Boltzmann machines. We present a musical encoding scheme and specifics of a learning and creational method. Our approach creates novel jazz licks, albeit not yet in real-time. The present work should be regarded as a feasibility study to determine whether such networks could be used at all. We do not claim superiority of this approach for pragmatically creating jazz
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Heritability of Unilateral Elbow Dysplasia in the Dog: A Retrospective Study of Sire and Dam Influence.
Canine elbow dysplasia is a significant health issue affecting many breeds. Unfortunately, treatments remain relatively limited, so control of this disease often falls to selectively breeding for dogs with normal elbows. The objectives of this study were to evaluate the heritability of left-sided vs. right-sided elbow dysplasia, and to assess potential differential sire and the dam influence on offspring elbow status. In a retrospective study, elbow data from 130,117 dogs over 2 years old representing 17 breeds were obtained from the database of the Orthopedic Foundation for Animals and included in the study. Heritability estimates for unilateral elbow dysplasia varied between breeds (ranging from 0.01 to 0.36) and were similar between the left and right elbows. The estimated genetic correlation between disease in the left and right elbow ~1 in the majority of breeds, with the exception of the hybrids, Australian Shepherds, and the Australian Cattle Dogs, likely due to low numbers of affected individuals. The sire and dam had equal impact on the offspring's elbow status. Furthermore, there was no increased risk for the sire or dam to pass on the same unilaterality of their elbow dysplasia to their offspring. However, the overall risk of elbow dysplasia in the offspring did increase when one or both parents were affected, though this also varied based on breed. Understanding of the impact that the sire and dam have on the offspring and of the overall heritability of both bilateral and unilateral elbow dysplasia is important in guiding breeding decisions to reduce the incidence in future generations of dogs
NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations
We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects)
cosmological simulations to study the effects of galaxy formation on key
properties of dark matter (DM) haloes. NIHAO consists of
high-resolution SPH simulations that include (metal-line) cooling, star
formation, and feedback from massive stars and SuperNovae, and cover a wide
stellar and halo mass range: ( ). When compared to DM-only simulations,
the NIHAO haloes have similar shapes at the virial radius, R_{\rm vir}, but are
substantially rounder inside . In NIHAO simulations
increases with halo mass and integrated star formation efficiency,
reaching at the Milky Way mass (compared to 0.5 in DM-only),
providing a plausible solution to the long-standing conflict between
observations and DM-only simulations. The radial profile of the phase-space
parameter () is best fit with a single power law in DM-only
simulations, but shows a flattening within for NIHAO
for total masses . Finally, the global velocity
distribution of DM is similar in both DM-only and NIHAO simulations, but in the
solar neighborhood, NIHAO galaxies deviate substantially from Maxwellian. The
distribution is more symmetric, roughly Gaussian, with a peak that shifts to
higher velocities for Milky Way mass haloes. We provide the distribution
parameters which can be used for predictions for direct DM detection
experiments. Our results underline the ability of the galaxy formation
processes to modify the properties of dark matter haloes.Comment: 19 pages, 17 figures, analysis strongly improved, main conclusions
unchanged, accepted for publication in MNRA
NIHAO IV: Core creation and destruction in dark matter density profiles across cosmic time
We use the NIHAO simulations to investigate the effects of baryonic physics
on the time evolution of Dark Matter central density profiles. The sample is
made of independent high resolution hydrodynamical simulations of
galaxy formation and covers a wide mass range: 1e10< Mhalo <1e12, i.e., from
dwarfs to L* . We confirm previous results on the dependence of the inner dark
matter density slope, , on the ratio between stellar-to-halo mass. We
show that this relation holds approximately at all redshifts (with an intrinsic
scatter of ~0.18 in ). This implies that in practically all haloes the
shape of their inner density profile changes quite substantially over cosmic
time, as they grow in stellar and total mass. Thus, depending on their final
stellar-to-halo mass ratio, haloes can either form and keep a substantial
density core (size~1 kpc), or form and then destroy the core and re-contract
the halo, going back to a cuspy profile, which is even steeper than CDM
predictions for massive galaxies (~1e12 Msun). We show that results from the
NIHAO suite are in good agreement with recent observational measurements of
in dwarf galaxies. Overall our results suggest that the notion of a
universal density profile for dark matter haloes is no longer valid in the
presence of galaxy formation.Comment: 11 pages, 13 figures. Corrected typo in table 2 (middle row) with
respect to the version published in MNRA
Period-color and amplitude-color relations in classical Cepheid variables V: The Small Magellanic Cloud Cepheid models
Period-colour (PC) and amplitude-colour (AC) relations at maximum, mean and
minimum light are constructed from a large grid of full amplitude hydrodynamic
models of Cepheids with a composition appropriate for the SMC (Small Magellanic
Cloud). We compare these theoretical relations with those from observations.
The theoretical relations are in general good agreement with their
observational counterparts though there exist some discrepancy for short period
(log [P] < 1) Cepheids. We outline a physical mechanism which can, in
principle, be one factor to explain the observed PC/AC relations for the long
and short period Cepheids in the Galaxy, LMC and SMC. Our explanation relies on
the hydrogen ionization front-photosphere interaction and the way this
interaction changes with pulsation period, pulsation phase and metallicity.
Since the PC relation is connected with the period-luminosity (PL) relation, it
is postulated that such a mechanism can also explain the observed properties of
the PL relation in these three galaxies.Comment: 10 pages, 6 figures and 6 tables, MNRAS accepte
Transformative climate change education and the school caretaker: a more-than-human analysis with young people
Schools are central to climate change education and climate-friendly transformations both as places which actually produce CO2 emissions and, above all, as educational institutions. Following a new materialist, transdisciplinary approach, we research here some of the
entanglements that constitute schools as whole institutions. As part of the research-education-cooperation k.i.d.Z.21_aCtiOn2 (Austrian Climate Research Program), our innovative approach meant that the situational analyses were conducted both by young people and collaborating researchers. The experiences and accounts were captured in situational maps that illustrate the entangled agencies of people, discussions, places
and matter relevant to CO2 reductions and transformation attempts. The analysis of those maps led to new perspectives on the intra-actions between the material and the discursive in schools. In particular, the caretakers’ entanglements with areas relevant to climate-friendly transformations are revealed as critical to transformative climate change education. We conclude with an outlook on schools becoming transformative, climate-friendly places by building on these kinds of entanglements and explicitly incorporating non-pedagogical aspects as part of a whole-school approach
High-Performance Wide-Area Optical Tracking: The HiBall Tracking System
Since the early 1980s, the Tracker Project at the University of North Carolina at Chapel Hill has been working on wide-area head tracking for virtual and augmented environments. Our long-term goal has been to achieve the high performance required for accurate visual simulation throughout our entire laboratory, beyond into the hallways, and eventually even outdoors. In this article, we present results and a complete description of our most recent electro-optical system, the HiBall Tracking System. In particular, we discuss motivation for the geometric configuration and describe the novel optical, mechanical, electronic, and algorithmic aspects that enable unprecedented speed, resolution, accuracy, robustness, and flexibility. </jats:p
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