546 research outputs found

    Phonological representations and repetition priming

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    An ubiquitous phenomenon in psychology is the `repetition effect': a repeated stimulus is processed better on the second occurrence than on the first. Yet, what counts as a repetition? When a spoken word is repeated, is it the acoustic shape or the linguistic type that matters? In the present study, we contrasted the contribution of acoustic and phonological features by using participants with different linguistic backgrounds: they came from two populations sharing a common vocabulary (Catalan) yet possessing different phonemic systems. They performed a lexical decision task with lists containing words that were repeated verbatim, as well as words that were repeated with one phonetic feature changed. The feature changes were phonemic, i.e. linguistically relevant, for one population, but not for the other. The results revealed that the repetition effect was modulated by linguistic, not acoustic, similarity: it depended on the subjects' phonemic system

    Dimensionality reduction for probabilistic movement primitives

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    Humans as well as humanoid robots can use a large number of degrees of freedom to solve very complex motor tasks. The high-dimensionality of these motor tasks adds difficulties to the control problem and machine learning algorithms. However, it is well known that the intrinsic dimensionality of many human movements is small in comparison to the number of employed DoFs, and hence, the movements can be represented by a small number of synergies encoding the couplings between DoFs. In this paper, we want to apply Dimensionality Reduction (DR) to a recent movement representation used in robotics, called Probabilistic Movement Primitives (ProMP). While ProMP have been shown to have many benefits, they suffer with the high-dimensionality of a robotic system as the number of parameters of a ProMP scales quadratically with the dimensionality. We use probablistic dimensionality reduction techniques based on expectation maximization to extract the unknown synergies from a given set of demonstrations. The ProMP representation is now estimated in the low-dimensional space of the synergies. We show that our dimensionality reduction is more efficient both for encoding a trajectory from data and for applying Reinforcement Learning with Relative Entropy Policy Search (REPS)

    Near-Infrared Light Curves of the Black Hole Binary A0620-00

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    We measured the near-infrared orbital light curve of the black hole binary A0620-00 in 1995 and 1996. The light curves show an asymmetric, double-humped modulation with extra emission in the peak at orbital phase 0.75. There were no significant changes in the shape of the light curve over the one-year observation period. There were no sharp dips in the light curves nor reversals of the asymmetry between the two peaks as seen in earlier observations. The light curves are well fit by models incorporating ellipsoidal variations from the mass-losing K-type star plus a beamed bright spot on the accretion disk around the compact star. The long-term stability of the light curve shape rules out superhumps and star spots as sources of asymmetry when we observed A0620-00. The ellipsoidal variations yield a lower limit i >= 38 deg on the orbital inclination. The light curves show no eclipse features, which places an upper limit i <= 75 deg. This range of inclinations constrains the mass of the compact object to 3.3 < M_1 < 13.6 Msun. The light curves do not further constrain the orbital inclination because the contribution of the accretion disk to the observed flux is unknown. We argue that a previous attempt to measure the near-infrared flux from the accretion disk using the dilution of the 12CO(2,0) bandhead in the spectrum of the K star is not reliable because the band strength depends strongly on surface gravity.Comment: Accepted for publication in the Astronomical Journal. 17 pages, 4 figures. Prepared using AASTEX V. 5.

    Status and Plans for the Array Control and Data Acquisition System of the Cherenkov Telescope Array

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    The Cherenkov Telescope Array (CTA) is the next-generation atmospheric Cherenkov gamma-ray observatory. CTA will consist of two installations, one in the northern, and the other in the southern hemisphere, containing tens of telescopes of different sizes. The CTA performance requirements and the inherent complexity associated with the operation, control and monitoring of such a large distributed multi-telescope array leads to new challenges in the field of the gamma-ray astronomy. The ACTL (array control and data acquisition) system will consist of the hardware and software that is necessary to control and monitor the CTA arrays, as well as to time-stamp, read-out, filter and store -at aggregated rates of few GB/s- the scientific data. The ACTL system must be flexible enough to permit the simultaneous automatic operation of multiple sub-arrays of telescopes with a minimum personnel effort on site. One of the challenges of the system is to provide a reliable integration of the control of a large and heterogeneous set of devices. Moreover, the system is required to be ready to adapt the observation schedule, on timescales of a few tens of seconds, to account for changing environmental conditions or to prioritize incoming scientific alerts from time-critical transient phenomena such as gamma ray bursts. This contribution provides a summary of the main design choices and plans for building the ACTL system.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

    Condición nutricional en la puna argentina

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    The purpose of the present study is to assess the nutritional status of two populations of the Argentinean Puna that hold different socioeconomic conditions: Susques (Jujuy province) and Antofagasta de la Sierra (Catamarca province). The sample consisted of 491 children aged 5 to 18 years old. It was measured weight, height and body mass index (BMI). The weight/age, height/age and BMI/age indexes were estimated and compared with the Frisancho´s (1990) and Cole´s et al. (2000) standard growth tables. Most of the subjects fell below the 50th percentile. The results of the direct anthropometric measurement showed high frequencies of underweight and stunting amongst both populations. Lower percentages of underweight and stunting were obtained when comparing the BMI. Boys and girls of Susques have a better nutritional condition than those from Antofagasta. These results could be explained for disparities in the socioeconomic conditions of both communities.El objetivo de este trabajo es evaluar la condición nutricional en dos poblaciones de la Puna argentina: Susques (provincia de Jujuy) y Antofagasta de la Sierra (provincia de Catamarca). Se analizaron 491 individuos entre 5 y 18 años de edad. Se obtuvieron el peso, la talla y el índice de masa corporal (IMC) y se calcularon los indicadores peso/edad, talla/edad e IMC/edad en relación a los estándares de Frisancho (1990) y Cole et al. (2000). La mayor parte de la población se encuentra concentrada por debajo del percentil 50. Los resultados muestran porcentajes relativamente altos de desnutrición aguda y crónica en función de las medidas directas, y más bajos al comparar el IMC. Los chicos y chicas de Susques muestran una situación nutricional algo mejor que Antofagasta, lo que se interpreta como consecuencia de mejores condiciones socioeconómicas

    Dollar exchange rate variability and agricultural policy: consequences on world agricultural prices with reference to Aargentina

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    The purpose of this paper is to analyze the consequences of dollar real exchange rate changes in agricultural markets with special reference to Argentina. This is done under different assumptions concerning exchange rate policies for Argentina and other countries involved, and also under different assumptions on market structure. Another main interest is also to know how U.S, agricultural and trade policies influence the markets in which Argentina sells its products.Facultad de Ciencias Económica

    Empirical Study of Carbon Dioxide Released to the Atmosphere during Commercial Red Grape Fermentation

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    Carbon dioxide (CO2) is a pollutant (greenhouse gas) that is emitted during winemaking but not currently regulated by the Environmental Protection Agency. While winery CO2 emissions have been modeled, they have never been measured continuously or confirmed during a commercial fermentation. As international interest increases in greenhouse gases, it is important to know the amount of CO2 release and the determining factors; yeast strain, temperature, and dissolved CO2 are potentially important parameters. The study was designed to quantify emissions and test a theoretical model for atmospheric release of CO2 during alcoholic fermentation in a commercial winery. Gas release was channeled through a manifold system with an in-line mass flow meter calibrated for CO2, providing real-time and integrated measurement of atmospheric emission. Intermittent use of a hot-wire anemometer was used as a check on the mass-flow measurements. Initial results indicate that integrated mass of CO2 release is dependent on total Brix decrease and not duration of fermentation, consistent with the Williams and Boulton model. However, the time course of release and the shape of the release curves differed substantially among ferments and were primarily dependent on the length of active fermentation
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