1,623 research outputs found
Temperature chaos in 3D Ising Spin Glasses is driven by rare events
Temperature chaos has often been reported in literature as a rare-event
driven phenomenon. However, this fact has always been ignored in the data
analysis, thus erasing the signal of the chaotic behavior (still rare in the
sizes achieved) and leading to an overall picture of a weak and gradual
phenomenon. On the contrary, our analysis relies on a large-deviations
functional that allows to discuss the size dependencies. In addition, we had at
our disposal unprecedentedly large configurations equilibrated at low
temperatures, thanks to the Janus computer. According to our results, when
temperature chaos occurs its effects are strong and can be felt even at short
distances.Comment: 5 pages, 5 figure
Post-Newtonian Dynamics in Dense Star Clusters: Highly-Eccentric, Highly-Spinning, and Repeated Binary Black Hole Mergers
We present models of realistic globular clusters with post-Newtonian dynamics
for black holes. By modeling the relativistic accelerations and
gravitational-wave emission in isolated binaries and during three- and
four-body encounters, we find that nearly half of all binary black hole mergers
occur inside the cluster, with about 10% of those mergers entering the
LIGO/Virgo band with eccentricities greater than 0.1. In-cluster mergers lead
to the birth of a second generation of black holes with larger masses and high
spins, which, depending on the black hole natal spins, can sometimes be
retained in the cluster and merge again. As a result, globular clusters can
produce merging binaries with detectable spins regardless of the birth spins of
black holes formed from massive stars. These second-generation black holes
would also populate any upper mass gap created by pair-instability supernovae.Comment: 9 pages, 3 figures, 2 appendices. To appear in Physical Review
Letter
Bounded and unbounded polynomials and multilinear forms: Characterizing continuity
In this paper we prove a characterization of continuity for polynomials on a
normed space. Namely, we prove that a polynomial is continuous if and only if
it maps compact sets into compact sets. We also provide a partial answer to the
question as to whether a polynomial is continuous if and only if it transforms
connected sets into connected sets. These results motivate the natural question
as to how many non-continuous polynomials there are on an infinite dimensional
normed space. A problem on the \emph{lineability} of the sets of non-continuous
polynomials and multilinear mappings on infinite dimensional normed spaces is
answered.Comment: 8 page
Poblaciones y comunidades de algas bentĂłnicas en la costa catalana
Las poblaciones de algas bentĂłnicas forman comunidades que en unos lugares están poco diferenciadas y en otros constituyen comunidades definidas de un cierto valor indicativo. En este trabajo se comentan diversos perfiles de la costa catalana, confeccionadas segĂşn esquemas tomados sobre el terreno y auxiliados por fotografĂas submarinas.Los perfiles, tomados en varias localidades de la costa, revelan algunos horizontes y facies caracterĂsticos del Mediterráneo occidental, lo que nos permite a modo de sĂntesis, tabular segĂşn su exposiciĂłn al oleaje y a la luz, las facies más conspicuas y mejor caracterizadas.The populations of benthic algae form communities which are little differenciated in some spots while in others they constitute definite communities with some indicative value. Several profiles of the catalan coast are treated in this paper they have been drawn in accordance with outlines taken on the ground and with the aid of submarine pictures.The profiles, taken at several spots of the coast, reveal some horizonts and facieswhich are characteristic of the west Mediterranean, this allows us to tabulate the facies more evidents and better characterized according to their exposure to the swell and to the light
Separation and fractionation of order and disorder in highly polydisperse systems
Microcanonical Monte Carlo simulations of a polydisperse soft-spheres model
for liquids and colloids have been performed for very large polydispersity, in
the region where a phase-separation is known to occur when the system (or part
of it) solidifies. By studying samples of different sizes, from N=256 to N=864,
we focus on the nature of the two distinct coexisting phases. Measurements of
crystalline order in particles of different size reveal that the solid phase
segregates between a crystalline solid with cubic symmetry and a disordered
phase. This phenomenon is termed fractionation.Comment: 8 pages, 5 figure
Sesgos en la obtención de estimas de densidad obtenidas por medio de transectos lineales en ambientes estepáricos de las Islas Canarias
We studied bias in density estimations derived from strip transects in dry open–country in the Canary Islands. We also present some critical remarks on GarcĂa–del–Rey’s (2005) paper regarding strip transects and the validity of comparisons based on population densities of birds in scrublands on Tenerife island using two different methods: territory mapping and strip transect sampling. Although strip transects with census belts of 25 m do not account for detectability, this method only slightly undervalues true density estimates, and allowed to detect more than 85% of birds present in poorly vegetated environments in the Canary Islands. Previously published works on distribution and abundance of terrestrial birds in the Canary Islands using the strip transect sampling with belts of 25 m on both sides of the observer, thus provide reliable information that only slightly underestimates true densities.
Key words: Birds, Canary Islands, Census methods, Strip transects, Open–country environments, Population
density, Territory mapping.We studied bias in density estimations derived from strip transects in dry open–country in the Canary Islands. We also present some critical remarks on GarcĂa–del–Rey’s (2005) paper regarding strip transects and the validity of comparisons based on population densities of birds in scrublands on Tenerife island using two different methods: territory mapping and strip transect sampling. Although strip transects with census belts of 25 m do not account for detectability, this method only slightly undervalues true density estimates, and allowed to detect more than 85% of birds present in poorly vegetated environments in the Canary Islands. Previously published works on distribution and abundance of terrestrial birds in the Canary Islands using the strip transect sampling with belts of 25 m on both sides of the observer, thus provide reliable information that only slightly underestimates true densities.
Key words: Birds, Canary Islands, Census methods, Strip transects, Open–country environments, Population
density, Territory mapping.Se estudian los sesgos derivados del empleo del mĂ©todo del taxiado (transectos lineales con bandas de 25 m a cada lado del observador) para obtener densidades en ambientes estepáricos de las Islas Canarias. TambiĂ©n se presentan algunos comentarios crĂticos al trabajo de GarcĂa–del–Rey (2005) que compara estimas de densidad obtenidas en Tenerife utilizando dos mĂ©todos diferentes: mapeo de territorios y transecto lineal. Aunque el mĂ©todo del taxiado estima densidades relativas no corregidas por la detectabilidad de las especies, este mĂ©todo proporciona valores de densidad muy parecidos a los reales, ya que permite detectar en ambientes con poca cobertura vegetal a más del 85% de los individuos dentro de bandas de 25 m a cada lado del observador. Por tanto, los trabajos previamente publicados sobre densidades de aves en Canarias proporcionan estimas fiables sĂłlo ligeramente infravaloradas.
Palabras clave: Aves, Islas Canarias, Métodos de censo, Transecto lineal, Ambientes estepáricos, Densidad
de poblaciĂłn, Mapeo de territorios
Gravitational waves from intermediate-mass black holes in young clusters
Massive young clusters (YCs) are expected to host intermediate-mass black
holes (IMBHs) born via runaway collapse. These IMBHs are likely in binaries and
can undergo mergers with other compact objects, such as stellar mass black
holes (BHs) and neutron stars (NSs). We derive the frequency of such mergers
starting from information available in the Local Universe. Mergers of IMBH-NS
and IMBH-BH binaries are sources of gravitational waves (GWs), which might
allow us to reveal the presence of IMBHs. We thus examine their detectability
by current and future GW observatories, both ground- and space-based. In
particular, as representative of different classes of instruments we consider
Initial and Advanced LIGO, the Einstein gravitational-wave Telescope (ET) and
the Laser Interferometer Space Antenna (LISA). We find that IMBH mergers are
unlikely to be detected with instruments operating at the current sensitivity
(Initial LIGO). LISA detections are disfavored by the mass range of IMBH-NS and
IMBH-BH binaries: less than one event per year is expected to be observed by
such instrument. Advanced LIGO is expected to observe a few merger events
involving IMBH binaries in a 1-year long observation. Advanced LIGO is
particularly suited for mergers of relatively light IMBHs (~100 Msun) with
stellar mass BHs. The number of mergers detectable with ET is much larger: tens
(hundreds) of IMBH-NS (IMBH-BH) mergers might be observed per year, according
to the runaway collapse scenario for the formation of IMBHs. We note that our
results are affected by large uncertainties, produced by poor observational
constraints on many of the physical processes involved in this study, such as
the evolution of the YC density with redshift.[abridged]Comment: 29 pages, 4 figures, accepted for publication in Ap
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