998 resultados para 543.8


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Esta es una colección de 10 vídeos tutoriales que pueden ser empleados como material educativo en los cursos de fonética básica en el ámbito universitario. Los vídeos 1-3 tratan aspectos relacionados con la grabación: el tipo de micrófonos que se emplean, las clases de espacios en las que se suelen llevar a cabo la captura de señales de audio y las grabadoras que se suelen emplear. El vídeo 4 explora técnicas de captura y observación de datos de flujo y presión en fonética aerodinámica. Los vídeos 5-10 presentan información sobre los principales usos que se le brindan al programa Praat (Boersma y Weenink, 2014) en los estudios actuales de fonética acústica, desde la clase de información sobre modos de articulación de las consonantes que se puede identificar en oscilogramas hasta la creación de señales sonoras sintetizadas por medio de unos procedimientos que tiene el programa para tal propósito, los cuales son susceptibles de ser empleados en experimentos de percepción auditiva.

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In studying a proposed carbon monoxide reduction scheme an attempt has been made to synthesize bifunctional group 8 transition metal carbonyl complexes containing intramolecular nucleophiles. The incorporation of alkoxide nucleophiles through cyclopentadienyl ligands was hoped to encourage attack on carbonyl ligands thereby forming cyclic metallaesters. The attempts to synthesize these substituted cyclopentadienyl group 8 transition metal complexes have thus far been unsuccessful.

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The first synthesis of the cembranoid natural product (±)-7,8-epoxy-4-basmen-6- one (1) is described. Key steps of the synthetic route include the cationic cyclization of the acid chloride from 15 to provide the macrocycle 16, and the photochemical transannular radical cyclization of the ester 41 to form the tricyclic product 50. Product 50 was transformed into 1 in ten steps. Transition-state molecular modeling studies were found to provide accurate predictions of the structural and stereochemical outcomes of cyclization reactions explored experimentally in the development of the synthetic route to 1. These investigations should prove valuable in the development of transannular cyclization as a strategy for synthetic simplification.

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8-12 urte bitarteko umeen surf entrenamendu prozesua nola planifikatu behar da, murgilduta dauden etapa sentikorra kontuan hartuz.

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We report on the conversion of near-ultraviolet radiation of 250-350 nm into near-infrared emission of 970-1100 nm in Yb3+-doped transparent glass ceramics containing Ba2TiSi2O8 nanocrystals due to the energy transfer from the silicon-oxygen-related defects to Yb3+ ions. Efficient Yb3+ emission (F-2(5/2)-> F-2(7/2)) was detected under the excitation of defects absorption at 314 nm. The occurrence of energy transfer is proven by both steady state and time-resolved emission spectra, respectively, at 15 K. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 65% for 8 mol % Yb2O3 doped glass ceramic. These materials are promising for the enhancement of photovoltaic conversion efficiency of silicon solar cells via spectra modification.

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The purpose of this thesis is to present new observations of thermal-infrared radiation from asteroids. Stellar photometry was performed to provide standards for comparison with the asteroid data. The details of the photometry and the data reduction are discussed in Part 1. A system of standard stars is derived for wavelengths of 8.5, 10.5 and 11.6 µm and a new calibration is adopted. Sources of error are evaluated and comparisons are made with the data of other observers.

The observations and analysis of the thermal-emission observations of asteroids are presented in Part 2. Thermal-emission lightcurve and phase effect data are considered. Special color diagrams are introduced to display the observational data. These diagrams are free of any model-dependent assumptions and show that asteroids differ in their surface properties.

On the basis of photometric models, (4) Vesta is thought to have a bolometric Bond albedo of about 0.1, an emissivity greater than 0.7 and a true radius that is close to the model value of 300^(+50)_(-30)km. Model albedos and model radii are given for asteroids 1, 2, 4, 5, 6, 7, 15, 19, 20, 27, 39, 44, 68, 80, 324 and 674. The asteroid (324) Bamberga is extremely dark with a model (~bolometric Bond) albedo in the 0.01 - 0.02 range, which is thought to be the lowest albedo yet measured for any solar-system body. The crucial question about such low-albedo asteroids is their number and the distribution of their orbits.

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In this thesis we build a novel analysis framework to perform the direct extraction of all possible effective Higgs boson couplings to the neutral electroweak gauge bosons in the H → ZZ(*) → 4l channel also referred to as the golden channel. We use analytic expressions of the full decay differential cross sections for the H → VV' → 4l process, and the dominant irreducible standard model qq ̄ → 4l background where 4l = 2e2μ,4e,4μ. Detector effects are included through an explicit convolution of these analytic expressions with transfer functions that model the detector responses as well as acceptance and efficiency effects. Using the full set of decay observables, we construct an unbinned 8-dimensional detector level likelihood function which is con- tinuous in the effective couplings, and includes systematics. All potential anomalous couplings of HVV' where V = Z,γ are considered, allowing for general CP even/odd admixtures and any possible phases. We measure the CP-odd mixing between the tree-level HZZ coupling and higher order CP-odd couplings to be compatible with zero, and in the range [−0.40, 0.43], and the mixing between HZZ tree-level coupling and higher order CP -even coupling to be in the ranges [−0.66, −0.57] ∪ [−0.15, 1.00]; namely compatible with a standard model Higgs. We discuss the expected precision in determining the various HVV' couplings in future LHC runs. A powerful and at first glance surprising prediction of the analysis is that with 100-400 fb-1, the golden channel will be able to start probing the couplings of the Higgs boson to diphotons in the 4l channel. We discuss the implications and further optimization of the methods for the next LHC runs.

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The Nostoc 'Fa Tsai' is sometimes seen in Chinese cooking materials stores. It is investigated what 'Fa Tsai' consists of and where it originates.

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Eudiaptomus vulgaris Schmeil is the most abundant copepod in Lake Maggiore and forms also, in respect to other entomostraca, the most important element, through its average biomass and because it is fairly numerous throughout the year. Plankton samples collected in a systematic and quantitative way, gave the opportunity to study some aspects of the dynamics of the population of this copepod, in safety in view of the uncertainty which in this kind of study can ensue when samples are taken only at a single station - in consequence of the changes in size of population between different water masses. The results of the biometrical observations are of the population of Eudiaptomus vulgaris is presented.

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In freshwater environments of modest size and without notable ecological structure, there is usually present only one diaptomid species. When two or more diaptomid species are present in the same habitat, generally their body dimensions are distinctly different. There are only four examples of co-existence of Arctodiaptomus bacillifer (Koelb.) and Acanthodiaptomus denticornis (Wierz.) situated at higher altitudes alpine lakes. The article discusses the results of sampling in the summer of 1953 and the problem of the co-existence of Arctodiaptomus bacillifer, Acanthodiaptomus denticornis and Heterocope saliens.

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Glandular cells, other than the mucous cells, have been described in the skin of various groups of fish (Teleosts, Ganoids, Selachii) and they have been called 'albuminose' by various authors. The authors propose to study the albuminose cells in the skin of Torpedo ocellata Raf. from a histochemical point of view. The albuminose cells have a complex morphological structure and a correspondingly complicated histochemical make-up. One must treat them as an example of cell with secretions of a particular type, which must and will be better incorporated when more is known of characteristics existent in other species.

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This short translation presents the conclusions only of a study of the proposed method of rearing cyprinid fry in cages and how this method can increase the amount of material produced of the stocked fry.

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We describe high-efficiency diffraction gratings fabricated in fused silica at the wavelength of 632.8 nm by rigorous coupled-wave analysis (RCWA). High-density holographic gratings, if the groove density falls within the range of 1575-1630 lines/mm and the groove depth within the range of 1.1-1.3 microns, can realize high diffraction efficiencies at the wavelength of 632.8 nm, e.g., the first Bragg diffraction efficiency can theoretically achieve more than 93% both in TE- and TM-polarized incidences, which greatly reduces the polarization-dependent losses. Note that with different groove profiles further optimized, the maximum efficiency of more than 99.69% can be achieved for TM-polarized incidence, or 97.81% for TE-polarized incidence.

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We measured the differential cross section of the process γp → pƞ at the 1.5 GeV Caltech electron synchrotron, at photon energies from 0.8 to 1.45 GeV, at various angles between 45° and 100° in the center of mass. A counter-spark chamber array was used to determine the kinematics of all particles in the final state of the partial mode γp → pƞ (ƞ → 2γ). Analysis of 40,000 pictures yielded 6,000 events above a background which varied with energy from 5% to 30% of foreground. The cross section shows an energy dependence confirming earlier results up to 1000 MeV, but with improved statistics; it then remains roughly constant (at 50° C.M.), to 1.45 GeV. The data show a small angular variation, within the limited range covered, at energies between 1000 and 1100 MeV.

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La presente Tesis Doctoral está encaminada hacia el estudio de las cicloadiciones y su aplicación a la síntesis de moléculas marcadas y sensores de ADN fluorescentes. La primera línea de trabajo se basará en el diseño y síntesis de dos nuevos grupos de moléculas fluorescentes basadas en las benzo[a]imidazo[5,1,2-cd]indolizinas y en las 2,3,9c-triazociclo-penta[j,k]fluorenos mediante la cicloadición [8 + 2]. También se lleva a cabo la síntesis de los derivados los aductos [8+2] que pudieran interaccionar con el ADN y posteriores experimentos de unión al ADN de los compuestos sintetizados. Por otro lado, la segunda línea de investigación consistirá en la búsqueda de estrategias sintéticas para la obtención de un precursor de un inhibidor de HDAC para su utilización en estudios de biodistribución mediante técnicas basados en radioactividad, como son la de tomografía por emisión de positrones y el método de disección.