2,011 research outputs found

    Triple-Star Candidates Among the Kepler Binaries

    Get PDF
    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

    Full text link
    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

    Get PDF
    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

    Get PDF
    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-pTp_T ψψ\psi\psi production as signals for Double Parton scattering at hadron colliders

    Full text link
    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

    Get PDF
    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

    Get PDF
    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 Υ\Upsilon vector resonances of bottomonium below BBˉB\bar{B} 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

    Get PDF
    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 pppp and ppˉp\bar{p} 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

    Full text link
    [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). Dynamic capacity provision for wireless sensors connectivity: A profit optimization approach. International Journal of Distributed Sensor Networks (Online). 14(4):1-14. https://doi.org/10.1177/1550147718772544S114144Weiser, M. (1991). The Computer for the 21st Century. Scientific American, 265(3), 94-104. doi:10.1038/scientificamerican0991-94Gubbi, J., Buyya, R., Marusic, S., & Palaniswami, M. (2013). Internet of Things (IoT): A vision, architectural elements, and future directions. Future Generation Computer Systems, 29(7), 1645-1660. doi:10.1016/j.future.2013.01.010Perera, C., Zaslavsky, A., Christen, P., & Georgakopoulos, D. (2013). Sensing as a service model for smart cities supported by Internet of Things. Transactions on Emerging Telecommunications Technologies, 25(1), 81-93. doi:10.1002/ett.2704Wang, N., Hossain, E., & Bhargava, V. K. (2016). Joint Downlink Cell Association and Bandwidth Allocation for Wireless Backhauling in Two-Tier HetNets With Large-Scale Antenna Arrays. IEEE Transactions on Wireless Communications, 15(5), 3251-3268. doi:10.1109/twc.2016.2519401Chowdhury, M. Z., Jang, Y. M., & Haas, Z. J. (2013). Call admission control based on adaptive bandwidth allocation for wireless networks. Journal of Communications and Networks, 15(1), 15-24. doi:10.1109/jcn.2013.000005Nan, G., Mao, Z., Yu, M., Li, M., Wang, H., & Zhang, Y. (2014). Stackelberg Game for Bandwidth Allocation in Cloud-Based Wireless Live-Streaming Social Networks. IEEE Systems Journal, 8(1), 256-267. doi:10.1109/jsyst.2013.2253420Zhu, K., Niyato, D., Wang, P., & Han, Z. (2012). Dynamic Spectrum Leasing and Service Selection in Spectrum Secondary Market of Cognitive Radio Networks. IEEE Transactions on Wireless Communications, 11(3), 1136-1145. doi:10.1109/twc.2012.010312.110732Vamvakas, P., Tsiropoulou, E. E., & Papavassiliou, S. (2017). Dynamic Provider Selection & Power Resource Management in Competitive Wireless Communication Markets. Mobile Networks and Applications, 23(1), 86-99. doi:10.1007/s11036-017-0885-yNiyato, D., Hoang, D. T., Luong, N. C., Wang, P., Kim, D. I., & Han, Z. (2016). Smart data pricing models for the internet of things: a bundling strategy approach. IEEE Network, 30(2), 18-25. doi:10.1109/mnet.2016.7437020Guijarro, L., Pla, V., Vidal, J. R., & Naldi, M. (2016). Maximum-Profit Two-Sided Pricing in Service Platforms Based on Wireless Sensor Networks. IEEE Wireless Communications Letters, 5(1), 8-11. doi:10.1109/lwc.2015.2487259Romero, J., Guijarro, L., Pla, V., & Vidal, J. R. (2017). Price competition between a macrocell and a small-cell service provider with limited resources and optimal bandwidth user subscription: a game-theoretical model. Telecommunication Systems, 67(2), 195-209. doi:10.1007/s11235-017-0331-2Al Daoud, A., Alanyali, M., & Starobinski, D. (2010). Pricing Strategies for Spectrum Lease in Secondary Markets. IEEE/ACM Transactions on Networking, 18(2), 462-475. doi:10.1109/tnet.2009.2031176Do, C. T., Tran, N. H., Huh, E.-N., Hong, C. S., Niyato, D., & Han, Z. (2016). Dynamics of service selection and provider pricing game in heterogeneous cloud market. Journal of Network and Computer Applications, 69, 152-165. doi:10.1016/j.jnca.2016.04.012Tsiropoulou, E. E., Vamvakas, P., & Papavassiliou, S. (2017). Joint Customized Price and Power Control for Energy-Efficient Multi-Service Wireless Networks via S-Modular Theory. IEEE Transactions on Green Communications and Networking, 1(1), 17-28. doi:10.1109/tgcn.2017.2678207Sanchis-Cano, A., Romero, J., Sacoto-Cabrera, E., & Guijarro, L. (2017). Economic Feasibility of Wireless Sensor Network-Based Service Provision in a Duopoly Setting with a Monopolist Operator. Sensors, 17(12), 2727. doi:10.3390/s17122727Weber, T. A. (2011). Optimal Control Theory with Applications in Economics. doi:10.7551/mitpress/9780262015738.001.0001Mandjes, M. (2003). Pricing strategies under heterogeneous service requirements. Computer Networks, 42(2), 231-249. doi:10.1016/s1389-1286(03)00191-9Shariatmadari, H., Ratasuk, R., Iraji, S., Laya, A., Taleb, T., Jäntti, R., & Ghosh, A. (2015). Machine-type communications: current status and future perspectives toward 5G systems. IEEE Communications Magazine, 53(9), 10-17. doi:10.1109/mcom.2015.7263367Ng, C.-H., & Soong, B.-H. (2008). Queueing Modelling Fundamentals. doi:10.1002/9780470994672Mendelson, H. (1985). Pricing computer services: queueing effects. Communications of the ACM, 28(3), 312-321. doi:10.1145/3166.3171Altman, E., Boulogne, T., El-Azouzi, R., Jiménez, T., & Wynter, L. (2006). A survey on networking games in telecommunications. Computers & Operations Research, 33(2), 286-311. doi:10.1016/j.cor.2004.06.005Belleflamme, P., & Peitz, M. (2015). Industrial Organization. doi:10.1017/cbo9781107707139Reynolds, S. S. (1987). Capacity Investment, Preemption and Commitment in an Infinite Horizon Model. International Economic Review, 28(1), 69. doi:10.2307/2526860Barron, E. N. (2013). Game Theory. doi:10.1002/9781118547168Sandholm, W. (2009). Pairwise Comparison Dynamics and Evolutionary Foundations for Nash Equilibrium. Games, 1(1), 3-17. doi:10.3390/g1010003Schlag, K. H. (1998). Why Imitate, and If So, How? Journal of Economic Theory, 78(1), 130-156. doi:10.1006/jeth.1997.234

    Induction heating of planetary interiors in white dwarf systems

    Get PDF
    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
    corecore