2,011 research outputs found
Triple-Star Candidates Among the Kepler Binaries
We present the results of a search through the photometric database of
eclipsing Kepler binaries (Prsa et al. 2011; Slawson et al. 2011) looking for
evidence of hierarchical triple star systems. The presence of a third star
orbiting the binary can be inferred from eclipse timing variations. We apply a
simple algorithm in an automated determination of the eclipse times for all
2157 binaries. The "calculated" eclipse times, based on a constant period
model, are subtracted from those observed. The resulting O-C (observed minus
calculated times) curves are then visually inspected for periodicities in order
to find triple-star candidates. After eliminating false positives due to the
beat frequency between the ~1/2-hour Kepler cadence and the binary period, 39
candidate triple systems were identified. The periodic O-C curves for these
candidates were then fit for contributions from both the classical Roemer delay
and so-called "physical" delay, in an attempt to extract a number of the system
parameters of the triple. We discuss the limitations of the information that
can be inferred from these O-C curves without further supplemental input, e.g.,
ground-based spectroscopy. Based on the limited range of orbital periods for
the triple star systems to which this search is sensitive, we can extrapolate
to estimate that at least 20% of all close binaries have tertiary companions.Comment: 19 pages, 13 figures, 3 tables; ApJ, 2013, 768, 33; corrected Fig. 7,
updated references, minor fixes to tex
Cosmological analogies in the search for new physics in high-energy collisions
In this paper, analogies between multiparticle production in high-energy
collisions and the time evolution of the early universe are discussed. A common
explanation is put forward under the assumption of an unconventional early
state: a rapidly expanding universe before recombination (last scattering
surface), followed by the CMB, later evolving up to present days, versus the
formation of hidden/dark states in hadronic collisions followed by a
conventional QCD parton shower yielding final-state particles. In particular,
long-range angular correlations are considered pointing out deep connections
between the two physical cases potentially useful for the discovery of new
physics.Comment: 9 pages, 5 figure
M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems
We have searched the Kepler light curves of ~3900 M-star targets for evidence
of periodicities that indicate, by means of the effects of starspots, rapid
stellar rotation. Several analysis techniques, including Fourier transforms,
inspection of folded light curves, 'sonograms', and phase tracking of
individual modulation cycles, were applied in order to distinguish the
periodicities due to rapid rotation from those due to stellar pulsations,
eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets
with rotation periods, P_rot, of < 2 days, and 110 with P_rot < 1 day. Some 30
of the 178 systems exhibit two or more independent short periods within the
same Kepler photometric aperture, while several have three or more short
periods. Adaptive optics imaging and modeling of the Kepler pixel response
function for a subset of our sample support the conclusion that the targets
with multiple periods are highly likely to be relatively young physical binary,
triple, and even quadruple M star systems. We explore in detail the one object
with four incommensurate periods all less than 1.2 days, and show that two of
the periods arise from one of a close pair of stars, while the other two arise
from the second star, which itself is probably a visual binary. If most of
these M-star systems with multiple periods turn out to be bound M stars, this
could prove a valuable way of discovering young hierarchical M-star systems;
the same approach may also be applicable to G and K stars. The ~5% occurrence
rate of rapid rotation among the ~3900 M star targets is consistent with spin
evolution models that include an initial contraction phase followed by magnetic
braking, wherein a typical M star can spend several hundred Myr before spinning
down to periods longer than 2 days.Comment: 17 pages, 12 figures, 2 tables; accepted for publication in The
Astrophysical Journa
Understanding Blood versus Blond Orange Consumption: A Cross-Cultural Study in Four Countries
Understanding consumer perceptions and attitudes to specific fruit is key information for not only increasing fruit consumption, but also for marketing reasons. It may also give clues to breeders to set quality objectives. This study explores different aspects that help to explain blood vs. blond orange consumption: availability and consumption habit, satisfaction attributes, facilitators and consumption barriers, consumption contexts, expectations and purchase intention. The study was conducted in China, Mexico, Spain and Italy, where citrus fruit consumers were invited to respond an online questionnaire. Our results revealed Italy as the country with the highest availability and consumption of blood oranges, followed by China, Mexico and Spain. "Liking" and "healthy properties" were the most important reasons for consumption irrespectively of orange type, but certain differences among countries were detected in secondary reasons. In all the countries, "juicy" was the most relevant attribute for consumer satisfaction, followed by flavour/taste attributes. "Aromatic" and "unfibrous" were substantial requirements for Italians and Chinese, while Spaniards attached importance to the blood oranges colour. Regarding consumption contexts, "eat with salt or chilly powder" was specific for Mexico, while "to improve health", "as a gift" or "at a restaurant" were contexts mainly cited in China. Despite taste preferences for other fruit being the main consumption barrier in all the countries for both orange types, the relevance of other barriers depended on culture and orange type. Mexican participants seemed to take a more neophobic attitude to blood oranges, while "inconvenient" was reported as a barrier for consuming blond ones in Spain and China. We conclude that blond and blood oranges can co-exist on markets at a high consumption rate, as in Italy. Specific interventions are needed in other countries because consumer attitudes to oranges, mainly blood ones, depend on culture
High- production as signals for Double Parton scattering at hadron colliders
We present an analysis of the \psi\psi production from double parton (DP)
sacttering and single parton (SP) scattering in the large p_T region via
color-octet gluon fragmentation. We find that at the Tevatron the DP \psi\psi
production is at the edge of the detectability at present, and at the LHC the
DP cross section will dominate over the SP cross section in the lower p_T(min)
region (i.e., p_T(min)<7GeV). We also conclude that the color-octet mechanism
is of crucial importance to the double j/psi production at high energy hadron
colliders.Comment: Revtex, 12 pages, 3 Postscript figure
Uncovering Trait Associations Resulting in Maximal Seed Yield in Winter and Spring Oilseed Rape
Seed yield is a complex trait for many crop species including oilseed rape (OSR) (Brassica napus), the second most important oilseed crop worldwide. Studies have focused on the contribution of distinct factors in seed yield such as environmental cues, agronomical practices, growth conditions, or specific phenotypic traits at the whole plant level, such as number of pods in a plant. However, how female reproductive traits contribute to whole plant level traits, and hence to seed yield, has been largely ignored. Here, we describe the combined contribution of 33 phenotypic traits within a B. napus diversity set population and their trade-offs at the whole plant and organ level, along with their interaction with plant level traits. Our results revealed that both Winter OSR (WOSR) and Spring OSR (SOSR); the two more economically important OSR groups in terms of oil production; share a common dominant reproductive strategy for seed yield. In this strategy, the main inflorescence is the principal source of seed yield, producing a good number of ovules, a large number of long pods with a concomitantly high number of seeds per pod. Moreover, we observed that WOSR opted for additional reproductive strategies than SOSR, presenting more plasticity to maximise seed yield. Overall, we conclude that OSR adopts a key strategy to ensure maximal seed yield and propose an ideal ideotype highlighting crucial phenotypic traits that could be potential targets for breeding
Searching for New Physics in Leptonic Decays of Bottomonium
New Physics can show up in various well-known processes already studied in
the Standard Model, in particular by modifying decay rates to some extent. In
this work, I examine leptonic decays of vector resonances of
bottomonium below production, subsequent to a magnetic dipole
radiative structural transition of the vector resonance yielding a pseudoscalar
continuum state, searching for the existence of a light Higgs-like neutral
boson that would imply a slight but experimentally measurable breaking of
lepton universality.Comment: LaTeX, 12 pages, 1 EPS figur
Fragmentation production of doubly heavy baryons
Baryons with a single heavy quark are being studied experimentally at
present. Baryons with two units of heavy flavor will be abundantly produced not
only at future colliders, but also at existing facilities. In this paper we
study the production via heavy quark fragmentation of baryons containing two
heavy quarks at the Tevatron, the LHC, HERA, and the NLC. The production rate
is woefully small at HERA and at the NLC, but significant at and
machines. We present distributions in various kinematical variables
in addition to the integrated cross sections at hadron colliders.Comment: 13 pages, macro package epsfig needed, 6 .eps figure files in a
separate uuencoded, compressed and tarred file; complete paper available at
http://www.physics.carleton.ca/~mad/papers/paper.p
Dynamic capacity provision for wireless sensors connectivity: A profit optimization approach
[EN] We model a wireless sensors' connectivity scenario mathematically and analyze it using capacity provision mechanisms, with the objective of maximizing the profits of a network operator. The scenario has several sensors' clusters with each one having one sink node, which uploads the sensing data gathered in the cluster through the wireless connectivity of a network operator. The scenario is analyzed both as a static game and as a dynamic game, each one with two stages, using game theory. The sinks' behavior is characterized with a utility function related to the mean service time and the price paid to the operator for the service. The objective of the operator is to maximize its profits by optimizing the network capacity. In the static game, the sinks' subscription decision is modeled using a population game. In the dynamic game, the sinks' behavior is modeled using an evolutionary game and the replicator dynamic, while the operator optimal capacity is obtained solving an optimal control problem. The scenario is shown feasible from an economic point of view. In addition, the dynamic capacity provision optimization is shown as a valid mechanism for maximizing the operator profits, as well as a useful tool to analyze evolving scenarios. Finally, the dynamic analysis opens the possibility to study more complex scenarios using the differential game extension.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Spanish Ministry of Economy and Competitiveness through project TIN2013-47272-C2-1-R; AEI/FEDER, UE through project TEC2017-85830-C2-1-P; and co-supported by the European Social Fund BES-2014-068998.Sanchis-Cano, Á.; Guijarro, L.; Condoluci, M. (2018). 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Induction heating of planetary interiors in white dwarf systems
Context. White dwarfs are the last evolutionary stage for the majority of main-sequence stars. With nuclear burning having ceased, these stars are slowly cooling. There is observational evidence indicating that planetary remnants, and possibly even planets, orbit a considerable fraction of the known white dwarf population. These objects are interesting targets for transit observations due to their large planet-to-star radius ratio. Especially interesting is the possible outgassing from such objects and their eventual observational prospects.
Aims. Here, we investigate whether electromagnetic induction heating can drive additional volcanic outgassing from small planetary remnants orbiting white dwarfs. This mechanism can be important for such bodies in addition to tidal heating due to the extremely strong magnetic fields of some white dwarfs and close orbital distances of planets to their host stars.
Methods. We calculated the heating and related magmatic effects for a Moon-sized body around a magnetized white dwarf using an analytical model for induction heating and a numerical model for interior processes. We also calculated induction heating inside asteroid-sized bodies.
Results. We show that induction heating can melt the mantle of a Moon-sized object within a geologically short time and contribute to desiccation of small asteroids on extremely tight orbits. These findings can have important implications for the evolution of rocky bodies orbiting white dwarfs and the potential detection of their outgassing
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