2,958 research outputs found

    Scaling properties of delay times in one-dimensional random media

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    The scaling properties of the inverse moments of Wigner delay times are investigated in finite one-dimensional (1D) random media with one channel attached to the boundary of the sample. We find that they follow a simple scaling law which is independent of the microscopic details of the random potential. Our theoretical considerations are confirmed numerically for systems as diverse as 1D disordered wires and optical lattices to microwave waveguides with correlated scatterers.Comment: 5 pages, 4 figures Submitted to Physical Review B Revision 2: 1) Theoretical curve fits added to Figures 1-4. 2) Scaling parameter added to inset of Figure 2. 3) Minor text changes to reflect referee comments. 4) Some extra refereces were adde

    Expected exponential loss for gaze-based video and volume ground truth annotation

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    Many recent machine learning approaches used in medical imaging are highly reliant on large amounts of image and ground truth data. In the context of object segmentation, pixel-wise annotations are extremely expensive to collect, especially in video and 3D volumes. To reduce this annotation burden, we propose a novel framework to allow annotators to simply observe the object to segment and record where they have looked at with a \$200 eye gaze tracker. Our method then estimates pixel-wise probabilities for the presence of the object throughout the sequence from which we train a classifier in semi-supervised setting using a novel Expected Exponential loss function. We show that our framework provides superior performances on a wide range of medical image settings compared to existing strategies and that our method can be combined with current crowd-sourcing paradigms as well.Comment: 9 pages, 5 figues, MICCAI 2017 - LABELS Worksho

    Scattering at the Anderson transition: Power--law banded random matrix model

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    We analyze the scattering properties of a periodic one-dimensional system at criticality represented by the so-called power-law banded random matrix model at the metal insulator transition. We focus on the scaling of Wigner delay times τ\tau and resonance widths Γ\Gamma. We found that the typical values of τ\tau and Γ\Gamma (calculated as the geometric mean) scale with the system size LL as τtypLD1\tau^{\tiny typ}\propto L^{D_1} and ΓtypL(2D2)\Gamma^{\tiny typ} \propto L^{-(2-D_2)}, where D1D_1 is the information dimension and D2D_2 is the correlation dimension of eigenfunctions of the corresponding closed system.Comment: 6 pages, 8 figure

    Mesoscopic mean-field theory for spin-boson chains in quantum optical systems

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    We present a theoretical description of a system of many spins strongly coupled to a bosonic chain. We rely on the use of a spin-wave theory describing the Gaussian fluctuations around the mean-field solution, and focus on spin-boson chains arising as a generalization of the Dicke Hamiltonian. Our model is motivated by experimental setups such as trapped ions, or atoms/qubits coupled to cavity arrays. This situation corresponds to the cooperative (E⊗β) Jahn-Teller distortion studied in solid-state physics. However, the ability to tune the parameters of the model in quantum optical setups opens up a variety of novel intriguing situations. The main focus of this paper is to review the spin-wave theoretical description of this problem as well as to test the validity of mean-field theory. Our main result is that deviations from mean-field effects are determined by the interplay between magnetic order and mesoscopic cooperativity effects, being the latter strongly size-dependent

    «Y de estas escogí catorce»: la versión española de las «Novelle» de Bandello

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    In this article we unravel the reasons why Vincent de Millis translated Matteo Bandello’s Novelle (1554) from the French translation of Pierre Boaistuau and François de Belleforest; how he manipulated the source text and what changes separate the Historias trágicas ejemplares (1589) from the Histoires tragiques (1559) and the Novelle. To do so, we focus on the comparison of some particularly violent scenes and their denouements, a true sample of the strategies used by Boaistuau, Belleforest, and Millis, to carry out the truculent adaptation of the Italian material to the new context where they write and translate.A lo largo del presente artículo intentaremos desgranar las razones por las que Vicente de Millis tradujo las Novelle (1554) de Matteo Bandello a partir de la traducción francesa de Pierre Boaistuau y François de Belleforest; de qué manera manipuló el texto de partida y qué cambios separan las Historias trágicas ejemplares (1589) de las Histoires tragiques (1559) y las Novelle. Para ello, nos centraremos en el cotejo de algunas escenas particularmente violentas y sus desenlaces, verdadero muestrario de las estrategias utilizadas por Boaistuau, Belleforest y, finalmente, Millis, para la adaptación truculenta de la materia italiana al nuevo contexto desde el que escriben y traducen.

    SJM: Un simulador de jerarquías de memoria orientado a la docencia de arquitectura de computadores

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    El concepto de jerarquía de memoria de un computador es uno de los más importantes en el ámbito de la docencia en arquitectura de computadores. Habitualmente, los distintos aspectos de la estructura y el funcionamiento de la jerarquía de memoria (memoria cache, memoria virtual, algoritmos de reemplazo, tasas de fallos, etc.) se explican primero a los alumnos de manera teórica, y posteriormente se realizan prácticas basadas en programas que simulan dicha jerarquía. En este trabajo se presenta un nuevo simulador pedagógico, SJM, que permite modelar de forma amigable distintas jerarquías de memoria, modificar fácilmente sus características y obtener medidas de sus prestaciones, de cara a que los alumnos, mediante la evaluación de distintas configuraciones de la jerarquía de memoria, afiancen su comprensión de los distintos aspectos de ésta.Peer Reviewe

    Laboratory Characterization and Astrophysical Detection of Vibrationally Excited States of Vinyl Cyanide in Orion-KL

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    New laboratory data of CH2_2CHCN (vinyl cyanide) in its ground and vibrationally excited states at the microwave to THz domain allow searching for these excited state transitions in the Orion-KL line survey. Frequency-modulated spectrometers combined into a single broadband 50-1900 GHz spectrum provided measurements of CH2_2CHCN covering a spectral range of 18-1893 GHz, whose assignments was confirmed by Stark modulation spectra in the 18-40 GHz region and by ab-initio anharmonic force field calculations. For analyzing the emission lines of CH2_2CHCN species detected in Orion-KL we used the excitation and radiative transfer code (MADEX) at LTE conditions. The rotational transitions of the ground state of this molecule emerge from four cloud components of hot core nature which trace the physical and chemical conditions of high mass star forming regions in the Orion-KL Nebula. The total column density of CH2_2CHCN in the ground state is (3.0±\pm0.9)x1015^{15} cm2^{-2}. We report on the first interstellar detection of transitions in the v10=1/(v11=1,v15=1) dyad in space, and in the v11=2 and v11=3 states in Orion-KL. The lowest energy vibrationally excited states of vinyl cyanide such as v11=1 (at 328.5 K), v15=1 (at 478.6 K), v11=2 (at 657.8 K), the v10=1/(v11=1,v15=1) dyad (at 806.4/809.9 K), and v11=3 (at 987.9 K) are populated under warm and dense conditions, so they probe the hottest parts of the Orion-KL source. Column density and rotational and vibrational temperatures for CH2_2CHCN in their ground and excited states, as well as for the isotopologues, have been constrained by means of a sample of more than 1000 lines in this survey. Moreover, we present the detection of methyl isocyanide (CH3_3NC) for the first time in Orion-KL and a tentative detection of vinyl isocyanide (CH2_2CHNC) and give column density ratios between the cyanide and isocyanide isomers.Comment: 46 pages, 22 figures, 14 tables, 9 online table
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