12 research outputs found

    The EBLM project: VI. Mass and radius of five low-mass stars in F+M binaries discovered by the WASP survey

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    Some M-dwarfs around F-/G-type stars have been measured to be hotter and larger than predicted by stellar evolution models. Inconsistencies between observations and models need to be addressed with more mass, radius, and luminosity measurements of low-mass stars to test and refine evolutionary models. Our aim is to measure the masses, radii and ages of the stars in five low-mass eclipsing binary systems discovered by the WASP survey. We used WASP photometry to establish eclipse-time ephemerides and to obtain initial estimates for the transit depth and width. Radial velocity measurements were simultaneously fitted with follow-up photometry to find the best-fitting orbital solution. This solution was combined with measurements of atmospheric parameters to interpolate evolutionary models and estimate the mass of the primary star, and the mass and radius of the M-dwarf companion. We assess how the best fitting orbital solution changes if an alternative limb-darkening law is used and quantify the systematic effects of unresolved companions. We also gauge how the best-fitting evolutionary model changes if different values are used for the mixing length parameter and helium enhancement. We report the mass and radius of five M-dwarfs and find little evidence of inflation with respect to evolutionary models. The primary stars in two systems are near the “blue hook” stage of their post sequence evolution, resulting in two possible solutions for mass and age. We find that choices in helium enhancement and mixing-length parameter can introduce an additional 3−5% uncertainty in measured M-dwarf mass. Unresolved companions can introduce an additional 3−8% uncertainty in the radius of an M-dwarf, while the choice of limb-darkening law can introduce up to an additional 2% uncertainty. The choices in orbital fitting and evolutionary models can introduce significant uncertainties in measurements of physical properties of such systems

    Greenberger-Horne-Zeilinger states and few-body Hamiltonians

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    The generation of Greenberger-Horne-Zeilinger (GHZ) states is a crucial problem in quantum information. We derive general conditions for obtaining GHZ states as eigenstates of a Hamiltonian. We find that a necessary condition for an n-qubit GHZ state to be a nondegenerate eigenstate of a Hamiltonian is the presence of m-qubit couplings with m[(n+1)/2]m \geq [(n+1)/2]. Moreover, we introduce a Hamiltonian with a GHZ eigenstate and derive sufficient conditions for the removal of the degeneracy

    QUANTUM IMAGING FOR SPACE OBJECTS

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    We aim at developing novel imaging instruments that exploit the intrinsic spatio-temporal correlations of astronomical light sources to bring the quantum advantage in space imaging. These novel instruments differ from standard imaging systems in the way images are retrieved. Conventional images are obtained from direct measurement of the intensity of light coming from the object of interest and recorded by a sensor. Here, instead, we first register optical intensities on two disjoint sensors, and then measure correlations between them. After a brief overview on the state of the art of quantum imaging for space objects, we describe the working principle of Correlation Plenoptic Imaging, which enables to perform 3D imaging and refocusing of outof-focus objects, and a possible application to satellite imaging

    Unearthing wave-function renormalization effects in the time evolution of a Bose-Einstein condensate

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    We study the time evolution of a Bose-Einstein condensate in an accelerated optical lattice. When the condensate has a narrow quasi-momentum distribution and the optical lattice is shallow, the survival probability in the ground band exhibits a step-like structure. In this regime, we establish a connection between the wave-function renormalization parameter Z and the phenomenon of resonantly enhanced tunneling

    EGFR mutations detected on cytology samples by a centralized laboratory reliably predict response to gefitinib in non-small cell lung carcinoma patients.

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    BACKGROUND: Epidermal growth factor receptor (EGFR) mutations are reliably detected by referral laboratories, even if most lung cancer cytology specimens sent to such laboratories contain very few cells. However, EGFR mutations may be distributed heterogeneously within tumors, thereby raising concerns that mutations detected on cytology are not representative of the entire tumor and, thus, are less reliable in predicting response to tyrosine kinase inhibitor (TKI) treatment than mutations detected on histology. To address this issue, the authors reviewed their clinical practice archives and compared the outcome of TKI treatment among patients who were selected by cytology versus patients who were selected by histology. METHODS: From July 2010 to July 2012, 364 cytology samples and 318 histology samples were received. Exon 19 deletions and the L858R point mutation in exon 21, detected by fragment assay and TaqMan assay, respectively, were confirmed by direct sequencing; discrepancies were resolved by cloning polymerase chain reaction products. The response rate (RR) and progression-free survival (PFS) at 12 months (range, 3-34 months) were evaluable in 13 EGFRmutated patients who were selected for treatment by cytology and 13 patients who were selected by histology. RESULTS: The mutation rate was similar in histology samples (8.5%) and cytology samples (8.8%). The RR (54%) and PFS (9.2 months) were similar in histologically selected patients and cytologically selected patients (RR, 62%; PFS, 8.6 months; P5.88). The disease control rate (responsive plus stable disease) was 92% in histologically selected patients and 100% in cytologically selected patients. CONCLUSIONS: EGFR mutations detected on cytology specimens by a centralized laboratory can predict TKI treatment response equally well as mutations identified on histology samples

    Electroweak parameters of the z0 resonance and the standard model

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    Contains fulltext : 124399.pdf (publisher's version ) (Open Access

    Measurement of B - anti-B mixing at the Z

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    From more than 175 000 hadronic Z decays observed with the ALEPH detector at LEP, we select 823 events with pairs of leptons in the final state. From these we measure χ, the probability thata b hadron which is observed to decay originated as a hadron. We find χ=0.132−0.026+0.027
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