5,583 research outputs found
The Segment Ontology: Bridging Music-generic and Domain-specific
Existing semantic representations of music analysis encapsulate narrow sub-domain concepts and are frequently scoped by the context of a particular MIR task. Segmentation is a crucial abstraction in the investigation of phenomena which unfold over time; we present a Segment Ontology as the backbone of an approach that models properties from the musicological domain independently from MIR implementations and their signal processing foundations, whilst maintaining an accurate and complete description of the relationships that link them. This framework provides two principal advantages which are explored through several examples: a layered separation of concerns that aligns the model with the needs of the users and systems that consume and produce the data; and the ability to link multiple analyses of differing types through transforms to and from the Segment axis
Implementation of classical communication in a quantum world
Observations of quantum systems carried out by finite observers who
subsequently communicate their results using classical data structures can be
described as "local operations, classical communication" (LOCC) observations.
The implementation of LOCC observations by the Hamiltonian dynamics prescribed
by minimal quantum mechanics is investigated. It is shown that LOCC
observations cannot be described using decoherence considerations alone, but
rather require the \textit{a priori} stipulation of a positive operator-valued
measure (POVM) about which communicating observers agree. It is also shown that
the transfer of classical information from system to observer can be described
in terms of system-observer entanglement, raising the possibility that an
apparatus implementing an appropriate POVM can reveal the entangled
system-observer states that implement LOCC observations.Comment: 17 pages, 2 figures; final versio
Structure and Composition of Tree Islands and Krummholz within the Forest-Tundra Ecotone in Central and Eastern Canada
The forest-tundra ecotone is expected to experience some of the initial effects of climate change. At the forefront of this transition zone, we find clonal growth forms of stunted and deformed trees with and without taller erect trees, called tree islands and krummholz, respectively. We sought to assess the potential effects of expansion of these clonal growth forms on tundra plant species at two Canadian locations, one in the Mealy Mountains of Labrador and the other near Churchill, Manitoba. Our objectives were 1) to analyze the structure (height distribution and shape) of these clonal growth forms to determine whether they are expanding; 2) to compare tree cover on the leeward and windward sides of clonal growths and 3) to assess patterns in individual plant species across these growth forms. Cover of trees and other plant species was measured at both locations, while tree stems were mapped near Churchill only. The presence of seedlings and symmetric patterns of tree height suggest that half of the tree islands near Churchill may be expanding. The edges of tree islands and krummholz may harbour safe sites for tundra plant species, as shown by peaks in cover of individual species at these edges. Our results suggest that expansion of tree islands and krummholz would affect the abundance of tundra plant species, which could lead to changes in species composition and biodiversity.On sâattend Ă ce que lâĂ©cotone de la toundra forestiĂšre subisse dans une certaine mesure les premiers effets du changement climatique. Ă lâavant-plan de cette zone de transition se trouvent des formes de croissance clonales dâarbres rabougris et difformes parfois assortis ou non assortis de plus grands arbres dressĂ©s, ce que lâon appelle des Ăźlots boisĂ©s et des krummholz, respectivement. Nous avons cherchĂ© Ă Ă©valuer les effets potentiels de lâexpansion de ces formes de croissance clonales sur les espĂšces vĂ©gĂ©tales de la toundra Ă deux emplacements situĂ©s au Canada, un aux monts Mealy du Labrador et lâautre prĂšs de Churchill, au Manitoba. Nos objectifs Ă©taient les suivants : 1) analyser la structure (rĂ©partition des hauteurs et formes) de ces formes de croissance clonales afin de dĂ©terminer si elles prennent de lâexpansion; 2) comparer la couverture arborescente en aval et en amont des croissances clonales; et 3) Ă©valuer les modĂšles se dessinant chez les diverses espĂšces vĂ©gĂ©tales individuelles au sein de ces formes de croissance. Les couvertures arborescentes et dâautres espĂšces vĂ©gĂ©tales ont Ă©tĂ© mesurĂ©es aux deux endroits, tandis que les tiges dâarbres nâont Ă©tĂ© relevĂ©es quâĂ lâemplacement de Churchill. La prĂ©sence de semis et de modĂšles symĂ©triques en ce qui a trait Ă la hauteur des arbres suggĂšre que la moitiĂ© des Ăźlots boisĂ©s prĂšs de Churchill pourraient ĂȘtre en expansion. Le bord des Ăźlots boisĂ©s et des krummholz pourrait constituer des lieux sĂ»rs pour les espĂšces vĂ©gĂ©tales de la toundra, comme lâindiquent les crĂȘtes caractĂ©risant la couverture des espĂšces individuelles situĂ©es en bordure. Nos rĂ©sultats laissent entendre que lâexpansion des Ăźlots boisĂ©s et des krummholz aurait des incidences sur lâabondance des espĂšces vĂ©gĂ©tales de la toundra, ce qui pourrait entraĂźner des changements sur le plan de la composition et de la biodiversitĂ© des espĂšces
Refractive Corneal Lenticule Extraction on Previous Photorefractive Keratectomy, with Optical Coherence Tomography Study
We report the first case of refractive corneal lenticule extraction with the femtosecond laser application CLEAR as retreatment technique after previous laser vision correction. A 42-year-old woman, operated by bilateral photorefractive keratectomy (PRK) 19 years previously, with moderate dry eye, came for post-PRK regression and underwent correction of a residual myopia of â3 â0.5 Ă 159° D in the left eye by CLEAR. Surgery was uneventful, with a regular laser pattern and a normal dissection of the lenticule. At day 1, uncorrected visual acuity was 20/25; at 3 months, it was 20/20, with a refraction of +0.25 Ă 115° D. The cornea and interface were regular and transparent; no dry eye symptoms occurred. At 3 months, on optical coherence tomography, the treatment was well centered, the surgical interface was centrally regular, whereas the anterior profile of the stromal surface was slightly corrugated, compensated by a smooth epithelial surface. The present case demonstrates that myopia after PRK can be achieved by CLEAR; an irregular stromal surface may occur, not affecting the visual result in virtue of epithelial remodeling
Dark matter from cosmic defects on galactic scales?
We discuss the possible dynamical role of extended cosmic defects on galactic
scales, specifically focusing on the possibility that they may provide the dark
matter suggested by the classical problem of galactic rotation curves. We
emphasize that the more standard defects (such as Goto-Nambu strings) are
unsuitable for this task, but show that more general models (such as transonic
wiggly strings) could in principle have a better chance. In any case, we show
that observational data severely restricts any such scenarios.Comment: Submitted to Phys. Rev. D (Brief Reports). v2: Reference added and
some typos corrected, matches published versio
Primordial Nucleosynthesis with CMB Inputs: Probing the Early Universe and Light Element Astrophysics
Cosmic microwave background (CMB) determinations of the baryon-to-photon
ratio will remove the last free
parameter from (standard) big bang nucleosynthesis (BBN) calculations. This
will make BBN a much sharper probe of early universe physics, for example,
greatly refining the BBN measurement of the effective number of light neutrino
species, . We show how the CMB can improve this limit, given
current light element data. Moreover, it will become possible to constrain
independent of \he4, by using other elements, notably deuterium;
this will allow for sharper limits and tests of systematics. For example, a 3%
measurement of , together with a 10% (3%) measurement of primordial D/H,
can measure to a 95% confidence level of \sigma_{95%}(N_\nu) =
1.8 (1.0) if . If instead, one adopts the
standard model value , then one can use (and its
uncertainty) from the CMB to make accurate predictions for the primordial
abundances. These determinations can in turn become key inputs in the
nucleosynthesis history (chemical evolution) of galaxies thereby placing
constraints on such models.Comment: 17 pages, 13 figures, plain LaTe
Complete Genome Sequence of Pelosinus fermentans JBW45, a Member of a Remarkably Competitive Group of Negativicutes in the Firmicutes Phylum.
The genome of Pelosinus fermentans JBW45, isolated from a chromium-contaminated site in Hanford, Washington, USA, has been completed with PacBio sequencing. Nine copies of the rRNA gene operon and multiple transposase genes with identical sequences resulted in breaks in the original draft genome and may suggest genomic instability of JBW45
Observation of interstellar lithium in the low-metallicity Small Magellanic Cloud
The primordial abundances of light elements produced in the standard theory
of Big Bang nucleosynthesis (BBN) depend only on the cosmic ratio of baryons to
photons, a quantity inferred from observations of the microwave background. The
predicted primordial 7Li abundance is four times that measured in the
atmospheres of Galactic halo stars. This discrepancy could be caused by
modification of surface lithium abundances during the stars' lifetimes or by
physics beyond the Standard Model that affects early nucleosynthesis. The
lithium abundance of low-metallicity gas provides an alternative constraint on
the primordial abundance and cosmic evolution of lithium that is not
susceptible to the in situ modifications that may affect stellar atmospheres.
Here we report observations of interstellar 7Li in the low-metallicity gas of
the Small Magellanic Cloud, a nearby galaxy with a quarter the Sun's
metallicity. The present-day 7Li abundance of the Small Magellanic Cloud is
nearly equal to the BBN predictions, severely constraining the amount of
possible subsequent enrichment of the gas by stellar and cosmic-ray
nucleosynthesis. Our measurements can be reconciled with standard BBN with an
extremely fine-tuned depletion of stellar Li with metallicity. They are also
consistent with non-standard BBN.Comment: Published in Nature. Includes main text and Supplementary
Information. Replaced with final title and abstrac
A Study of the Decays of 194,195,196-Pb
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
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