7,688 research outputs found
A spatially-structured PCG method for content diversity in a Physics-based simulation game
This paper presents a spatially-structured evolutionary algorithm (EA) to procedurally generate game maps of di ferent levels of di ficulty to be solved, in Gravityvolve!, a physics-based simulation videogame that we have implemented and which is inspired by the n-
body problem, a classical problem in the fi eld of physics and mathematics. The proposal consists of a steady-state EA whose population is partitioned into three groups according to the di ficulty of the generated content (hard, medium or easy) which can be easily adapted to handle the automatic creation of content of diverse nature in other games. In addition, we present three fitness functions, based on multiple criteria (i.e:, intersections, gravitational acceleration and simulations), that were used experimentally to conduct the search process for creating a database of
maps with di ferent di ficulty in Gravityvolve!.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Time series of high resolution spectra of SN 2014J observed with the TIGRE telescope
We present a time series of high resolution spectra of the Type Ia supernova
2014J, which exploded in the nearby galaxy M82. The spectra were obtained with
the HEROS echelle spectrograph installed at the 1.2 m TIGRE telescope. We
present a series of 33 spectra with a resolution of R = 20, 000, which covers
the important bright phases in the evolution of SN 2014J during the period from
January 24 to April 1 of 2014. The spectral evolution of SN 2014J is derived
empirically. The expansion velocities of the Si II P-Cygni features were
measured and show the expected decreasing behaviour, beginning with a high
velocity of 14,000 km/s on January 24. The Ca II infrared triplet feature shows
a high velocity component with expansion velocities of > 20, 000 km/s during
the early evolution apart from the normal component showing similar velocities
as Si II. Further broad P-Cygni profiles are exhibited by the principal lines
of Ca II, Mg II and Fe II. The TIGRE SN 2014J spectra also resolve several very
sharp Na I D doublet absorption components. Our analysis suggests interesting
substructures in the interstellar medium of the host galaxy M82, as well as in
our Milky Way, confirming other work on this SN. We were able to identify the
interstellar absorption of M82 in the lines of Ca II H & K at 3933 and 3968 A
as well as K I at 7664 and 7698 A. Furthermore, we confirm several Diffuse
Interstellar Bands, at wavelengths of 6196, 6283, 6376, 6379 and 6613 A and
give their measured equivalent widths.Comment: 11 pages, 10 figures, accepted for publication in MNRA
The ELAIS Deep X-ray Survey
We present initial follow-up results of the ELAIS Deep X-ray Survey which is
being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray
sources are detected in our two 75 ks ACIS-I observations in the well-studied
ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to
R=26 with a median magnitude of R=24. We show that objects which are unresolved
optically (i.e. quasars) follow a correlation between their optical and X-ray
fluxes, whereas galaxies do not. We also find that the quasars with fainter
optical counterparts have harder X-ray spectra, consistent with absorption at
both wavebands. Initial spectroscopic follow-up has revealed a large fraction
of high-luminosity Type 2 quasars. The prospects for studying the evolution of
the host galaxies of X-ray selected Type 2 AGN are considered.Comment: 9 pages, 5 figures, To appear in Proceedings of XXI Moriond
Conference: "Galaxy Clusters and the High Redshift Universe Observed in
X-rays", edited by D. Neumann, F.Durret, & J. Tran Thanh Va
Visible and near-infrared observations of asteroid 2012 DA14 during its closest approach of February 15, 2013
Near-Earth asteroid 2012 DA14 made its closest approach on February 15, 2013,
when it passed at a distance of 27,700 km from the Earth's surface. It was the
first time an asteroid of moderate size was predicted to approach that close to
the Earth, becoming bright enough to permit a detailed study from ground-based
telescopes. Asteroid 2012 DA14 was poorly characterized before its closest
approach. We acquired data using several telescopes on four Spanish
observatories: the 10.4m Gran Telescopio Canarias (GTC) and the 3.6m Telescopio
Nazionale Galileo (TNG), both in the El Roque de los Muchachos Observatory
(ORM, La Palma); the 2.2m CAHA telescope, in the Calar Alto Observatory
(Almeria); the f/3 0.77m telescope in the La Hita Observatory (Toledo); and the
f/8 1.5m telescope in the Sierra Nevada Observatory (OSN, Granada). We obtained
visible and near-infrared color photometry, visible spectra and time-series
photometry. Visible spectra together with color photometry of 2012 DA14 show
that it can be classified as an L-type asteroid, a rare spectral type with a
composition similar to that of carbonaceous chondrites. The time-series
photometry provides a rotational period of 8.95 +- 0.08 hours after the closest
approach, and there are indications that the object suffered a spin-up during
this event. The large amplitude of the light curve suggests that the object is
very elongated and irregular, with an equivalent diameter of around 18m. We
obtain an absolute magnitude of H_R = 24.5 +- 0.2, corresponding to H_V = 25.0
+- 0.2. The GTC photometry also gives H_V = 25.29 +- 0.14. Both values agree
with the value listed at the Minor Planet Center shortly after discovery. From
the absolute photometry, together with some constraints on size and shape, we
compute a geometric albedo of p_V = 0.44 +- 0.20, which is slightly above the
range of albedos known for L-type asteroids (0.082 - 0.405).Comment: 7 pages, 4 figures, 1 table. Accepted in A&A (June 17 2013
LEAN maintenance model based on change management allowing the reduction of delays in the production line of textile SMEs in Peru
This article examines the problem of production line delays in a textile small- and medium-sized enterprise (SME) that produces polyester fibre from recycled bottles, based on orders. Factors that have resulted in production line delays include prolonged unscheduled maintenance time, and preparations and adjustments prior to operating the equipment. To address the problem, a model was developed applying lean manufacturing tools through change management, with the aim of increasing equipment availability and useful life. To validate the model, a pilot was developed to determine how the increase in equipment availability helps reduce delays in the production line, which eventually improves completion of customer orders
Optical and X-ray properties of the RIXOS AGN: II - Emission lines
We present the optical and UV emission line properties of 160 X-ray selected
AGN taken from the RIXOS survey (including Halpha, Hbeta, [OIII]5007, MgII2798
and CIII]1909). This sample is believed to contain a mixture of absorbed and
unabsorbed objects, with column densities up to 4e21 cm-2. Although the
distribution of the [OIII] EW for the RIXOS AGN is typical of optically
selected samples, the Balmer line EWs are relatively low. This is consistent
with the presence of a dust absorber between the broad and narrow line regions
(eg. a molecular torus), and intrinsically weak optical line emission. We find
Baldwin effects in CIII] and MgII, and a positive response of the MgII line to
its ionizing continuum. There is a strong correlation between the EW and FWHM
of MgII, which may be similar to that seen in other samples for Hbeta. We
demonstrate that this is consistent with models which suggest two line-emitting
zones, a `very broad line region' (VBLR) and an `intermediate line region'
(ILR). The correlation between EW and FWHM in MgII may be a physical
characteristic of the ILR or it may reflect a geometric dependence. We found no
correlation between the Hbeta FWHM and the slope of the X-ray spectrum, however
this may be due to the effects of dust absorption which suppresses the broad
Hbeta component, masking any relationship. The Halpha FWHM does tend to be
narrow when alpha_X is soft, and broadens as alpha_X hardens, although the
formal probability for this correlation is low (91 per cent). If the
distribution of alpha_X in the RIXOS sample reflects the level of intrinsic
absorption in these AGN, the data suggest a possible link between the velocity
of the Balmer line-emitting region and the amount of absorbing material beyond.Comment: 29 pages, 14 figures, to be published in Monthly Notices of the Royal
Astronomical Society. Also available from
http://www.mssl.ucl.ac.uk/www_astro/preprints/preprints.htm
Spain's Budget Neglects Research
Letter.-- Carlos Fenollosa et al.Peer Reviewe
Elevated synaptic vesicle release probability in synaptophysin/gyrin family quadruple knockouts
Synaptophysins 1 and 2 and synaptogyrins 1 and 3 constitute a major family of
synaptic vesicle membrane proteins. Unlike other widely expressed synaptic vesicle proteins such
as vSNAREs and synaptotagmins, the primary function has not been resolved. Here, we report
robust elevation in the probability of release of readily releasable vesicles with both high and low
release probabilities at a variety of synapse types from knockout mice missing all four family
members. Neither the number of readily releasable vesicles, nor the timing of recruitment to the
readily releasable pool was affected. The results suggest that family members serve as negative
regulators of neurotransmission, acting directly at the level of exocytosis to dampen connection
strength selectively when presynaptic action potentials fire at low frequency. The widespread
expression suggests that chemical synapses may play a frequency filtering role in biological
computation that is more elemental than presently envisioned
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