23,651 research outputs found
What do cells actually want?
Genome-scale models require an objective function representing what an organism strives for. A method has been developed to infer this fundamental biological function from data.Please see related Research article: www.dx.doi.org/10.1186/s13059-016-0968-2
Bounding invariants of fat points using a coding theory construction
Let Z \subseteq \proj{n} be a fat points scheme, and let be the
minimum distance of the linear code constructed from . We show that
imposes constraints (i.e., upper bounds) on some specific shifts in the graded
minimal free resolution of , the defining ideal of . We investigate
this relation in the case that the support of is a complete intersection;
when is reduced and a complete intersection we give lower bounds for
that improve upon known bounds.Comment: 18 pages, 1 figure; accepted in J. Pure Appl. Algebr
Orientations of hamiltonian cycles in large digraphs
We prove that, with some exceptions, every digraph with n ≥ 9 vertices and at least (n - 1) (n - 2) + 2 arcs contains all orientations of a Hamiltonian cycle
Subjective evaluation of an emerging theory of low-frequency sound source localization in closed acoustic spaces
An earlier reported theory of low-frequency sound-source localization within closed acoustic spaces proposed that virtual image acuity is strongly dependent on sufficient inter-arrival time between a direct sound and its first reflection. This current study aims to test the theory’s predictions by subjective experiment where participants are required to indicate perceived sound source direction, but without knowledge of loudspeaker location. Test signals of frequencies 40 Hz to 115 Hz take the form of either windowed sine or square waves. Results confirm broad agreement with theoretical expectations and support the conjecture, contrary to common expectation, that low-frequency sound localization within the context of closed acoustic spaces is possible, although strongly dependent on system configuration and size of a listening space
Low-frequency sound source localization as a function of closed acoustic spaces
Further development of an emerging generalized theory of low-frequency sound localization in closed listening spaces is presented that aims to resolve the ambiguities inherent in previous research. The approach takes a robust set of equations based on source/listener location, reverberation time and room dimensions and tests them against a set of evaluation procedures to explore image location against theoretical expectations. Phantom imaging is germane to the methodology and its match within the theoretical framework is investigated. Binaural recordings are used to inspect a range of closed environments for localization clues each with a range of source-listener placements. A complementary series of small-scale listening tests are included for perceptual validation
Integrable subsystem of Yang--Mills dilaton theory
With the help of the Cho-Faddeev-Niemi-Shabanov decomposition of the SU(2)
Yang-Mills field, we find an integrable subsystem of SU(2) Yang-Mills theory
coupled to the dilaton. Here integrability means the existence of infinitely
many symmetries and infinitely many conserved currents. Further, we construct
infinitely many static solutions of this integrable subsystem. These solutions
can be identified with certain limiting solutions of the full system, which
have been found previously in the context of numerical investigations of the
Yang-Mills dilaton theory. In addition, we derive a Bogomolny bound for the
integrable subsystem and show that our static solutions are, in fact, Bogomolny
solutions. This explains the linear growth of their energies with the
topological charge, which has been observed previously. Finally, we discuss
some generalisations.Comment: 25 pages, LaTex. Version 3: appendix added where the equivalence of
the field equations for the full model and the submodel is demonstrated;
references and some comments adde
Hairy black holes in the general Skyrme model
We study the existence of hairy black holes in the generalized
Einstein-Skyrme model. It is proven that in the BPS model limit there are no
hairy black hole solutions, although the model admits gravitating (and flat
space) solitons. Furthermore, we find strong evidence that a necessary
condition for the existence of black holes with Skyrmionic hair is the
inclusion of the Skyrme term . As an example, we show that there
are no hairy black holes in the
model and present a new kind of black hole solutions with compact Skyrmion hair
in the model.Comment: Latex file, 19 pages, 9 ps figures; v2: minor changes, some comments
added, coincides with published versio
Asteroids in GALEX: Near-ultraviolet photometry of the major taxonomic groups
We present ultraviolet photometry (NUV band, 180--280 nm) of 405 asteroids
observed serendipitously by the Galaxy Evolution Explorer (GALEX) from
2003--2012. All asteroids in this sample were detected by GALEX at least twice.
Unambiguous visible-color-based taxonomic labels (C type versus S type) exist
for 315 of these asteroids; of these, thermal-infrared-based diameters are
available for 245. We derive NUV-V color using two independent models to
predict the visual magnitude V at each NUV-detection epoch. Both V models
produce NUV-V distributions in which the S types are redder than C types with
more than 8-sigma confidence. This confirms that the S types' redder spectral
slopes in the visible remain redder than the C types' into the NUV, this
redness being consistent with absorption by silica-containing rocks. The GALEX
asteroid data confirm earlier results from the International Ultraviolet
Explorer, which two decades ago produced the only other sizeable set of UV
asteroid photometry. The GALEX-derived NUV-V data also agree with previously
published Hubble Space Telescope (HST) UV observations of asteroids 21 Lutetia
and 1 Ceres. Both the HST and GALEX data indicate that NUV band is less useful
than u band for distinguishing subgroups within the greater population of
visible-color-defined C types (notably, M types and G types).Comment: 13 pages, 11 figures, accepted 2015-May-6 to The Astrophysical
Journal. Includes one machine-readable table of NUV asteroid detections.
Version 2 includes a corrected citation to Waszczak et al. (2015) arXiv
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