565 research outputs found
Futur dels estudis de fonètica experimental del catalÃ
Proposta d'un pla de recerca sobre fonètica experimental: estat actual dels estudis, metodologia i instrumentació. Aspectes essencials que cal tenir en compte en el tractament del vocalisme i el consonantisme
Mètodes de normalització i de representació de dades acústiques i articulatòries
Aquest treball revisa alguns mètodes de normalització i de representació de dades acústiques i articulatòries. Pel que fa als mètodes de normalització de dades acústiques, el mètode Lobanov redueix de forma més satisfactòria que el mètode CILH les dades F1 x F2 de cinc, sis i set vocals de dialectes majors i menors del català . També s’apunten alguns mètodes de normalització i de representació de dades de contacte linguopalatal i de moviment lingual obtingudes mitjançant l’electropalatografia i l’articulometria midsagital electromagnètica.The present study reviews several normalization methods of acoustic and articulatory data. It is shown that the Lobanov normalization procedure performs better than CILH when F1 x F2 frequency data for five, six and seven vowel systems of major and minor Catalan dialects are taken into consideration. Several ways of normalizing and representing linguopalatal contact and tongue movement data obtained by means of electropalatography and electromagnetic midsagittal articulometry are also discussed
A methodology for the characterization of land use using medium-resolution spatial images
Introducción: La caracterización de los usos del suelo representa uno de los insumos indispensables para el manejo de los recursos naturales a diferentes escalas. Objetivo: Desarrollar una metodologÃa para caracterizar el uso del suelo en la cuenca superior del arroyo del Azul (Buenos Aires, Argentina), a través de la fusión de imágenes satelitales de media resolución espacial. Materiales y métodos: Se utilizó una serie temporal de 23 imágenes del Ãndice de vegetación de diferencia normalizada (NDVI, por sus siglas en inglés) del satélite MODIS-Terra (producto MOD13Q1) para el periodo mayo 2015 - mayo 2016. Además, se emplearon imágenes Landsat 8 para discriminar algunas categorÃas difÃciles de clasificar con NDVI-MODIS. El mapa final de coberturas se validó considerando puntos de verificación independientes al proceso de clasificación; su precisión se evaluó a través del estadÃstico Kappa. Resultados y discusión: La serie temporal de NDVI permitió reconocer los patrones fenológicos de las coberturas y usos del suelo de mayor representatividad en la región. Se discriminaron siete coberturas; los usos agrÃcolas representaron 81.5 % de la superficie, siendo el sistema de doble cultivo trigo-soya (soja en Argentina) el predominante (39.4 %). La precisión global del mapa final fue alta (88.9 %, coeficiente Kappa = 0.86). Conclusión: La metodologÃa empleada tiene la ventaja de ser rápida y replicable, para caracterizar los usos del suelo de una región determinada y evaluar sus cambios potenciales a lo largo del tiempo.Introduction: The characterization of land uses represents one of the essential inputs for the management of natural resources at different scales. Objective: To develop a methodology to characterize land use in the upper creek basin from the Azul stream (Buenos Aires, Argentina), through the fusion of satellite images with a medium spatial resolution. Materials and methods: A time-series of 23 images was used from the Normalized Difference Vegetation Index (NDVI) of the MODIS-Terra satellite (product MOD13Q1) for the period May 2015 - May 2016. Landsat 8 images were used to discriminate some categories difficult to classify with NDVI-MODIS. The final cover map was validated regarding verification points independent to the classification process; its accuracy was evaluated by means of the Kappa statistic. Results and discussion: The NDVI time series allowed to recognize the phenological patterns of the covers and land use of greater representativeness in the region. Seven land cover were discriminated; the agricultural uses represented 81.5 % of the surface, double-crop wheat-soya (soybean in Argentina) system predominated (39.4 %). The overall accuracy of the final map was high (88.9 %, Kappa coefficient = 0.86). Conclusion: The methodology used has the advantage of being quick and replicable, to characterize the land uses of a given region and to evaluate its potential changes over time.Fil: Guevara Ochoa, Cristian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Rectorado. Instituto de HidrologÃa de Llanuras - Sede Azul. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones CientÃficas. Instituto de HidrologÃa de Llanuras - Sede Azul; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Lara, Bruno Daniel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de AgronomÃa. Departamento Ciencias Básicas Agronómicas y Biológicas. Laboratorio de Investigación y Servicios en Teledetección de Azul; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Vives, Luis Sebastián. Universidad Nacional del Centro de la Provincia de Buenos Aires. Rectorado. Instituto de HidrologÃa de Llanuras - Sede Azul. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones CientÃficas. Instituto de HidrologÃa de Llanuras - Sede Azul; ArgentinaFil: Zimmermann, Erik Daniel. Universidad Nacional de Rosario. Facultad de Ciencias Exactas IngenierÃa y Agrimensura. Centro Universidad Rosario de Investigaciones Hidroambientales; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Gandini, Marcelo Luciano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de AgronomÃa. Departamento Ciencias Básicas Agronómicas y Biológicas. Laboratorio de Investigación y Servicios en Teledetección de Azul; Argentin
Optimal investment and hedging under partial and inside information
This article concerns optimal investment and hedging for agents who must use trading strategies which are adapted to the filtration generated by asset prices, possibly augmented with some inside information related to the future evolution of an asset price. The price evolution and observations are taken to be continuous, so the partial (and, when applicable, inside) information scenario is characterised by asset price processes with an unknown drift parameter, which is to be filtered from price observations. We first give an exposition of filtering theory, leading to the Kalman-Bucy filter. We outline the dual approach to portfolio optimisation, which is then applied to the Merton optimal investment problem when the agent does not know the drift parameter of the underlying stock. This is taken to be a random variable with a Gaussian prior distribution, which is updated via the Kalman filter. This results in a model with a stochastic drift process adapted to the observation filtration, and which can be treated as a full information problem, and an explicit solution to the optimal investment problem is possible. We also consider the same problem when the agent has noisy knowledge at time of the terminal value of the Brownian motion driving the stock. Using techniques of
enlargement of filtration to accommodate the insider's additional knowledge, followed by filtering the asset price drift, we are again able to obtain an explicit solution. Finally we treat an incomplete market hedging problem. A claim on a non-traded asset is hedged using a correlated traded asset. We summarise the full information case, then treat the partial information scenario in which the hedger is uncertain of the true values of the asset price
drifts. After filtering, the resulting problem with random drifts is solved in the case that each asset's prior distribution has the same variance, resulting in analytic approximations for the optimal hedging strategy
Estudi experimental de les consonants fricatives del mallorquà i del valenciÃ
Dades electropalatogrà fiques i acústiques indiquen que /s/ i /ʃ/són més anteriors en valencià que en mallorquÃ. A més a més, la /s/ valenciana és menys palatalitzada que la mallorquina per tal com s'articula amb menys contacte dorsopalatal i una constricció lingual més ampla en el primer dialecte. En qualsevol cas, els parlants valencians distingeixen les dues fricatives, sobretot pel que fa al grau de contacte dorsopalatal i a l'indret i a la llargada de la constricció alveolar, si bé aquesta diferència és clarament inferior a la que exhibeixen els parlants mallorquins. En valencià (però no pas en mallorquÃ), la realització de /s/ final de mot darrera de consonant palatal en mots com alls i anys està generalment a mig camà entre la corresponent a la /s/ de permÃs i a la /ʃ/ de guix. El fet que, en relació amb el mallorquÃ, la /s/ valenciana sigui menys palatalitzada de forma general però més palatalitzada (sense igualarse amb /ʃ/) en posició final de mot darrera de consonant palatal, suggereix que els grups finals de alls i anys experimenten coarticulació retardatòria en valencià . S'adiu amb aquesta possibilitat el fet que l'epèntesi d'oclusiva pugui actuar més freqüentment en el grup que en la seqüència /ʃs/ en aquest dialecte. A la llum de les dades articulatòries i acústiques d'aquest estudi, proposem una interpretació d'alguns aspectes relatius a l'evolució històrica de les dues fricatives linguals en català dialectal.Electropalatographic and acoustic data show that /s/ and /ʃ/ are fronter in Valencian than in Majorcan. Moreover, Valencian /s/ is less palatalized than Majorcan /s/ because it is articulated with less dorso-palatal contact and the tongue constriction is produced over a wider area. In any case, Valencian speakers distinguish the two fricatives, especially as regards the degree of dorso-palatal contact, and the place and length of the alveolar constriction, although this difference is clearly less pronounced than for Majorcan speakers. In Valencian (but not Majorcan), the realization of word-final /s/ after a palatal consonant, as in alls and anys, is generally half way between that of the /s/ of permÃs and the /ʃ/ of guix. The fact that, in comparison with Majorcan, Valencian /s/ is less palatalized on the whole, but more palatalized (without merging with /ʃ/) in word-final position after a palatal consonant, suggests that the final clusters of alls and anys undergo carryover co-articulation in Valencian. This possibility is supported by the fact that stop epenthesis operates more frequently in the cluster /s/ than in the sequence /ʎs/ in this dialect. In the light of the articulatory and acoustic data in this study, we propose an interpretation of some aspects about the historical evolution of lingual fricatives in Catalan dialects
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Chylous Leak During Posterior Approach to Juvenile Scoliosis Surgery: A Case Report.
CaseWe report the first documented case of chylous leak recognized intraoperatively during posterior spinal instrumentation and fusion for juvenile scoliosis in a female patient with a history of thoracotomy and decortication for an empyema.ConclusionsThoracic duct injury can lead to severe morbidity and mortality because of chylothorax formation. Although chylous leaks are a well-documented complication of the anterior approach to spine surgery, leaks during the posterior approach are rarely reported. When these chylous leaks are recognized intraoperatively, the likelihood of serious complications may be minimized by drain placement before closure
Modulation of pain threshold by virtual body ownership
Appropriate sensorimotor correlations can result in the illusion of ownership of exogenous body parts. Nevertheless, whether and how the illusion of owning a new body part affects human perception, and in particular pain detection, is still poorly investigated. Recent findings have shown that seeing one's own body is analgesic, but it is not known whether this effect is transferable to newly embodied, but exogenous, body parts. In recent years, results from our laboratory have demonstrated that a virtual body can be felt as one's own, provided realistic multisensory correlations
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