著者

edited by Lucy Grig and Gavin Kelly

出版者

Oxford University Press

巻号頁・発行日

2012

著者

edited by H.C.G. Matthew and Brian Harrison

出版者

Oxford University Press

巻号頁・発行日

2004

著者

Michael Anesko

出版者

Oxford University Press

巻号頁・発行日

1986

著者

Ohashi Kazuharu Leslie Alison Thomson James D.

出版者

Oxford University Press

雑誌

Behavioral ecology (ISSN:10452249)

巻号頁・発行日

vol.24, no.3, pp.768-778, 2013-05

被引用文献数

9

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Animals collecting food from renewable resource patches scattered in space often establish small foraging areas to which they return faithfully. Such area fidelity offers foraging advantages through selection of profitable patches, route minimization, and regular circuit visits to these patches (“trapline foraging”). Resource distribution under field conditions may often vary in time, however, especially when competitors suddenly vanish and a number of patches become available for their neighbors. Previous studies suggested that site-faithful foragers of bumble bees quickly respond to such unexpected events by readjusting their foraging areas, although it is not clear how much their foraging performance was improved, beyond the simple relaxation of competitive pressure, or how they manifest such flexibility while persistently using certain foraging areas or paths. Here, we conducted indoor flight-cage experiments with bumble bees and found that a bee, when encountering a loss of its competitor, improved its foraging performance to a greater extent than expected from a simple relaxation of competitive pressure by increasing the size of its foraging area. Moreover, bees with better-established traplines achieved greater foraging areas after the loss of competitors, suggesting that bees do not necessarily need to “sample” neighboring patches to monitor temporal changes in environments. We discuss how periodical returns and route memory associated with accurate reward values could allow inherently conservative trapliners to make flexible adjustments, by effectively monitoring their circumstances and quickly readjusting to detected changes.

著者

Umemura Masayuki Susa Hajime Hasegawa Kenji Suwa Tamon Semelin Benoit

出版者

Oxford University Press

雑誌

Progress of theoretical and experimental physics (ISSN:20503911)

巻号頁・発行日

vol.1, pp.01A306, 2012-10

被引用文献数

8

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Firstly, the formation of first objects driven by dark matter is revisited by high-resolution hydrodynamic simulations. It is revealed that dark matter halos of ∼104 M⊙ can produce first luminous objects with the aid of dark matter cusps. Therefore, the mass of first objects is smaller by roughly two orders of magnitude than in the previous prediction. This implies that the number of Population III stars formed in the early universe could be significantly larger than hitherto thought. Secondly, feedback by photo-ionization and photo-dissociation photons in the first objects is explored with radiation hydrodynamic simulations, and it is demonstrated that multiple stars can form in a 105 M⊙ halo. Thirdly, the fragmentation of an accretion disk around a primordial protostar is explored with photo-dissociation feedback. As a result, it is found that photo-dissociation can reduce the mass accretion rate onto protostars. Also, protostars as small as 0.8 M⊙ may be ejected and evolve while keeping their mass, which might be detected as the “real first stars” in the Galactic halo. Finally, state-of-the-art radiation hydrodynamic simulations are performed to investigate the internal ionization of first galaxies and the escape of ionizing photons. We find that UV feedback by forming massive stars enhances the escape fraction even in a halo as massive as > 6 × 109 M⊙, while it reduces the star formation rate significantly. This may have a momentous impact on cosmic reionization.

著者

Ozawa A. Uesaka T. Wakasugi M.

出版者

Oxford University Press

雑誌

Progress of theoretical and experimental physics (ISSN:20503911)

巻号頁・発行日

vol.2012, no.1, pp.03C009, 2012-12

被引用文献数

54

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We describe the rare-RI (radioactive isotope) ring at the RI Beam Factory (RIBF). The main purpose of the rare-RI ring is to measure the mass of very neutron-rich nuclei, the production rates of which are very small (hence ‘rare RI’) and the lifetimes of which are predicted to be very short. In the rare-RI ring, there are two innovative pieces of apparatus: individual injection, which can realize the injection of 200 A MeV rare RIs one by one, and a cyclotron-like storage ring, which allows high isochronous magnetic fields with large angular and momentum acceptances. With these devices, we will achieve a 10−6 mass resolution, and will be able to access rare RIs, the production rate of which is down to 1 event/day/pnA. Construction of the rare-RI ring started in fiscal year 2012.

著者

Ejiri Shinji Kanaya Kazuyuki Umeda Takashi

出版者

Oxford University Press

雑誌

Progress of theoretical and experimental physics (ISSN:20503911)

巻号頁・発行日

vol.2012, no.1, pp.01A104, 2012-09

被引用文献数

5 5

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The WHOT-QCD Collaboration is pushing forward a series of lattice studies of quantum chromodynamics (QCD) at finite temperatures and densities using improved Wilson quarks. Because Wilson-type quarks require more computational resources than the more widely used staggered-type quarks, various theoretical and computational techniques have to be developed and applied. In this paper, we introduce a fixed-scale approach armed with a T-integration method, a Gaussian method based on cumulant expansion, and a histogram method combined with the reweighting technique. Using these methods, we have carried out the first study of finite-density QCD with Wilson-type quarks and the first calculation of the equation of state with 2+1 flavors of Wilson-type quarks. We present the results of these studies and discuss perspectives towards clarification of the properties of 2+1 flavor QCD at the physical point at finite temperatures and densities.

著者

edited by Nicholas Thieberger

出版者

Oxford University Press

巻号頁・発行日

2012

著者

Terry Crowley edited and prepared for publication by Nick Thieberger

出版者

Oxford University Press

巻号頁・発行日

2007

著者

Annabel Robinson

出版者

Oxford University Press

巻号頁・発行日

2002

著者

Sun Lue Moritake Takashi Zheng Yun-Wen Suzuki Kenshi Gerelchuluun Ariungerel Hong Zhengshan Zenkoh Junko Taniguchi Hideki Tsuboi Koji

出版者

Oxford University Press

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.54, no.1, pp.61-69, 2013-01

被引用文献数

13

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One-third of patients with medulloblastoma die due to recurrence after various treatments including radiotherapy. Although it has been postulated that cancer stem-like cells are radio-resistant and play an important role in tumor recurrence, the “stemness” of medulloblastoma cells surviving irradiation has not yet been elucidated. Using a medulloblastoma cell line ONS-76, cells that survived gamma irradiation were investigated on their “stemness” in vitro. From 10 500 cells, 20 radio-resistant clones were selected after gamma ray irradiation (5 Gy × two fractions) using the replica micro-well technique. These 20 resistant clones were screened for CD133 positivity by flow cytometry followed by side population assay, tumor sphere formation assay and clonogenic survival assay. Results revealed CD133 fractions were significantly elevated in three clones, which also exhibited significantly increased levels of tumor sphere formation ability and side population fraction. Clonogenic survival assay demonstrated that their radio-resistance was significantly higher than the parental ONS-76. This may support the hypothesis that a small number of cancer stem-like cells (CSCs) are the main culprits in local recurrence after radiotherapy, and disruption of the resistance mechanism of these CSCs is a critical future issue in improving the outcome of patients with medulloblastoma.

著者

David Cunningham

出版者

Oxford University Press

巻号頁・発行日

2013

著者

Alan Cameron

出版者

Oxford University Press

巻号頁・発行日

2011

著者

William A. Johnson

出版者

Oxford University Press

巻号頁・発行日

2010

著者

John H. McWhorter

出版者

Oxford University Press

巻号頁・発行日

2005

著者

edited by Mark Durie Malcolm Ross

出版者

Oxford University Press

巻号頁・発行日

1996

著者

Ronald Chase

出版者

Oxford University Press

巻号頁・発行日

2002

著者

edited by David Shulman and Guy G. Stroumsa

出版者

Oxford University Press

巻号頁・発行日

1999

著者

Herbert A. Davidson

出版者

Oxford University Press

巻号頁・発行日

1992

著者

Athenagoras edited and translated by William R. Schoedel

出版者

Oxford University Press

巻号頁・発行日

1972