5,084 research outputs found
Lexical and phonological processing in visual word recognition by stuttering children: Evidence from Spanish
A number of studies have pointed out that stuttering-like disfluencies could be the result of failures in central and linguistic processing. The goal of the present paper is to analyze if stuttering implies deficits in the lexical and phonological processing in visual word recognition. This study compares the performance of 28 children with and without stuttering in a standard lexical decision task in a transparent orthography: Spanish. Word frequency and syllable frequency were manipulated in the experimental words. Stutterers were found to be considerably slower (in their correct responses) and produced more errors than the non- stutterers (?(1) = 36.63, p and lt;.001, ?2 =.60). There was also a facilitation effect of syllable frequency, restricted to low frequency words and only in the stutterers group (t1(10) = 3.67, p and lt;.005; t2(36) = 3.10, p and lt;.001). These outcomes appear to suggest that the decoding process of stutterers exhibits a deficit in the interface between the phonological-syllabic level and the word level. Copyright © Universidad Complutense de Madrid and Colegio Oficial de Psicólogos de Madrid 2014
Designing the physical metallurgy of a bainitic microalloyed steel with a dilatometer
During the past decade, medium carbon microalloyed steels have become increasingly important in the automotive sector. These steels are especially suitable for automobile components such as connecting rods, crankshafts and wheel hubs. Their mechanical properties are generally adequate in most cases although their toughnesses are consistently low. High toughness can be obtained in medium carbon microalloyed bainitic steel (38MnV7) after a careful control of the chemistry and heat thermal treatment. An specific chemical composition of a 38MnV7 steel has been developed, providing impact energies after Charpy-V tests at room temperature as high as 40J (the steel in bainitic state). Present work is oriented to an optimization of the above chemical composition by control of the Transformation Time Temperature (TTT) curves as well as the Precipitation Time Temperatures (PTT) curves of the present microallying elements. To attain this purpose six different casting were prepared, ranging the chemical composition as follows %C: 0.35-0.46, %Mn: 1.33-1.84, %V: 0.066-0.14% and %Ti: 0.010- 0.025. To appropriate design the thermal cycle, TTT curves were determined for each steel at two austenitization conditions, in order to promote fine and large initial grain sizes.. PTT curves were determined by the stress relaxation technique, a method which can be also be used to derive recrystrallization kinetics. All curves, TTT and PTT curves where derived by using a quenching dilatometer Bahr DIL805A/D.
While the TTT curves were obtained in a classical way, the relaxation test consist in sample austenization followed by cooling down to the testing temperature. After a short stabilization period of 10s, samples are deformed to different strain levels and then relaxed, i.e. deformation is kept constant and the variation of the stress with the time is recorded. The different deformation levels are selected to evaluate the effect of deformation on precipitation characteristics. The relaxation curves under these conditions gave information about the kinetics of precipitation when there is no plastic deformation and, thus, generation of dislocations involved. Results are finally discussed in terms of the chemical composition, initial microstructure and precipitates interaction.Peer Reviewe
Toxicity of several d-endotoxins of Bacillus thuringiensis against Helicoverpa armigera (Lepidoptera: Noctuidae) from Spain
Toxicity and larval growth inhibition of eleven insecticidal proteins of Bacillus thuringiensis were evaluated against neonate larvae of Helicoverpa armigera, a major pest of important crops in Spain and other countries, by a whole-diet contamination method. The most active toxins were Cry1Ac4 and Cry2Aa1, with LC50 values of 3.5 and 6.3 μg/ml, respectively. At the concentrations tested, Cry1Ac4, Cry2Aa1, Cry9Ca, Cry1Fa1, Cry1Ab3, Cry2Ab2, Cry1Da, and Cry1Ja1, produced a significant growth inhibition, whereas Cry1Aa3, Cry1Ca2, and Cry1Ea had no effect
Temporal stimulated intersubband emission of photoexcited electrons
We have studied the transient evolution of electrons distributed over two
levels in a wide quantum well, with the two levels below the optical phonon
energy, after an ultrafast interband excitation and cascade emission of optical
phonons. If electrons are distributed near the top of the passive region, a
temporal negative absorption appears to be dominant in the intersubband
response. This is due to the effective broadening of the upper level state
under the optical phonon emission. We have then considered the amplification of
the ground mode in a THz waveguide with a multiquantum well placed at the
center of the cavity. A huge increase of the probe signal is obtained, which
permits the temporal stimulated emission regime of the photoexcited electrons
in the THz spectral region.Comment: 5 pages, 5 figures, brief repor
Effects of Jatropha lubricant thermo-oxidation on the tribological behaviour of engine cylinder liners as measured by a reciprocating friction test
Bio-lubricants have emerged as a potential and viable way to replace, totally or partially, mineral oils due to their effectiveness in the boundary lubrication regime for different applications, including, automotive engine operation. However, the effect of thermo-oxidation caused by the long-term use of the bio-lubricants on their tribological properties has been scarcely analysed. In this work, the effect of thermo-oxidation of Jatropha oil (JO), an engine mineral oil (EMO) and a blend made up of 80%vol. EMO and 20%vol. JO (B20) on the tribological behaviour of a simulated piston ring/engine cylinder liner interface was studied in reciprocating friction tests at 26 and 100 °C. The oils were thermally oxidized and characterized in terms of carbonyl compounds, depletion of ZDDP additives, changes in kinematic viscosity and viscosity index. Friction coefficients, wear rates and scar morphologies were assessed. Thermo-oxidation resulted in significant viscosity increases in JO compared to EMO and B20. Also, it generated increased friction coefficients for JO and B20. However, they were lower than those for fresh and aged EMO. EMO increased the wear rate after thermo-oxidation in contrast to JO. Smearing was generated using most oil samples while severe scuffing was only produced by using fresh JO at 100 °C
On the implementation of a dynamic direction modulation system with vector modulators
Dynamic directional modulation (DDM) has already proven to be an efficient technique to achieve physical layer security in wireless communications. System architectures based on vector modulators provide a flexible framework to implement synthesis methods that allow us to obtain increased security and/or independent multichannel transmissions. However, the implementation of DDM with vector modulators requires an accurate calibration (amplitude and phase) of every component in the RF path. In this contribution, we study the sensitivity of the response of a DDM system based on commercial vector modulators showing how to correct the nonideal behavior of all the components thanks to the flexibility provided by the vector modulator
Experimental measurement of the quality factor of a Fabry-P\'erot open-cavity axion haloscope
The axion is a hypothetical boson arising from the most natural solution to
the problem of charge and parity symmetry in the strong nuclear force.
Moreover, this pseudoscalar emerges as a dark matter candidate in a parameter
space extending several decades in mass. The Dark-photons \& Axion-Like
particles Interferometer (DALI) is a proposal to search for axion dark matter
in a range that remains under-examined. Currently in a design and prototyping
phase, this haloscope is a multilayer Fabry-P\'erot interferometer. A
proof-of-principle experiment is performed to observe the resonance in a
prototype. The test unveils a quality factor per open cavity of a few hundred
over a bandwidth of the order of dozens of megahertz. The result elucidates a
physics potential to find the, so far elusive, axion, in a sector which can
simultaneously solve the symmetry problem in the strong interaction and the
enigma of dark matter.Comment: 5 pages, 6 figure
Cultura y clima de la seguridad como factores de protección frente a los riesgos ocupacionales
La presente revisión bibliográfica es una contextualización acerca del Clima y la Cultura de
Seguridad Organizacional, así como también algunos de los instrumentos y formas de medición
más utilizados para evaluar estas temáticas. Se pretendió afirmar o probar que tanto la Cultura
como el Clima de Seguridad en las distintas organizaciones, pueden convertirse en factores de
protección ante los riesgos ocupacionales; e incluso como factores predictores ante la ocurrencia
de la accidentalidad y siniestralidad laboral. Para llevar a cabo esta monografía fue necesario
revisar muchos artículos, teniendo preferencia aquellos estudios que fueron realizados y
publicados en los últimos quince años. Como resultado, se puede decir que las investigaciones
realizadas al respecto muestran algunas limitaciones, nuevas direcciones a tomar, además
apuntan a confirmar que tan protectores pueden llegar a ser la cultura y el clima de seguridad
frente a la percepción que tengan los empleados sobre los riesgos a los que están expuestos a
diario en sus sitios de trabajo.Incluye bibliografí
- …