Search results for "Rafa"
showing 8 items of 268 documents
Ultrafast Coherent THz Lattice Dynamics Coupled to Spins in the van der Waals Antiferromagnet FePS3
2022
Coherent THz optical lattice and hybridized phonon–magnon modes are triggered by femtosecond laser pulses in the antiferromagnetic van der Waals semiconductor FePS3. The laser-driven lattice and spin dynamics are investigated in a bulk crystal as well as in a 380 nm-thick exfoliated flake as a function of the excitation photon energy, sample temperature and applied magnetic field. The pump-probe magneto-optical measurements reveal that the amplitude of a coherent phonon mode oscillating at 3.2 THz decreases as the sample is heated up to the Néel temperature. This signal eventually vanishes as the phase transition to the paramagnetic phase occurs, thus revealing its connection to the long-ra…
Higher-order Nonnegative CANDECOMP/PARAFAC Tensor Decomposition Using Proximal Algorithm
2019
Tensor decomposition is a powerful tool for analyzing multiway data. Nowadays, with the fast development of multisensor technology, more and more data appear in higherorder (order > 4) and nonnegative form. However, the decomposition of higher-order nonnegative tensor suffers from poor convergence and low speed. In this study, we propose a new nonnegative CANDECOM/PARAFAC (NCP) model using proximal algorithm. The block principal pivoting method in alternating nonnegative least squares (ANLS) framework is employed to minimize the objective function. Our method can guarantee the convergence and accelerate the computation. The results of experiments on both synthetic and real data demonstrate …
Molecule-like photodynamics of Au102(pMBA)44 nanocluster.
2015
Photophysical properties of a water-soluble cluster Au102(pMBA)44 (pMBA = para-mercaptobenzoic acid) are studied by ultrafast time-resolved mid-IR spectroscopy and density functional theory calculations in order to distinguish between molecular and metallic behavior. In the mid-IR transient absorption studies, visible or near-infrared light is used to electronically excite the sample, and the subsequent relaxation is monitored by studying the transient absorption of a vibrational mode in the ligands. Based on these studies, a complete picture of energy relaxation dynamics is obtained: (1) 0.5-1.5 ps electronic relaxation, (2) 6.8 ps vibrational cooling, (3) intersystem crossing from the low…
Sparse nonnegative tensor decomposition using proximal algorithm and inexact block coordinate descent scheme
2021
Nonnegative tensor decomposition is a versatile tool for multiway data analysis, by which the extracted components are nonnegative and usually sparse. Nevertheless, the sparsity is only a side effect and cannot be explicitly controlled without additional regularization. In this paper, we investigated the nonnegative CANDECOMP/PARAFAC (NCP) decomposition with the sparse regularization item using l1-norm (sparse NCP). When high sparsity is imposed, the factor matrices will contain more zero components and will not be of full column rank. Thus, the sparse NCP is prone to rank deficiency, and the algorithms of sparse NCP may not converge. In this paper, we proposed a novel model of sparse NCP w…
Ultrafast solvent-assisted level crossing in 1-Naphthol
2013
The nonadiabatic inversion dynamics of the energetic order of the electronic excited states of the photoacid 1-naphthol have been revealed by ultrafast spectroscopy on a femtosecond timescale (see picture; IC=internal conversion). The energetic order of the excited states La and Lb of 1-naphthol is reversed in 60 fs in polar dimethyl sulfoxide solvent.
Unges egne erfaringer med frafall fra videregående opplæring : en kvalitativ intervjustudie med ungdom i frafallsforebyggende tiltak
2016
Masteroppgave psykisk helsearbeid - Universitetet i Agder 2016 Konfidensiell til / confidential until 01.01.2022
Historias de vida de menores vulnerables: procesos y factores de exclusión social de género
2020
Este artículo es fruto de un trabajo de campo etnográfico realizado en distintos centros de protección de mujeres de la Comunidad Valenciana (España). Su objetivo es analizar los procesos y factores de exclusión social de las mujeres institucionalizadas cuando eran menores de edad. La metodología de investigación utilizada ha sido de índole cualitativa. Así, a través de observación participante, informes sociales, documentos personales y, sobre todo, entrevistas informales y en profundidad, se han podido elaborar quince historias de vida. Aunque, en esta aproximación sólo se analizan las de las menores que inician su trayectoria vital en la situación de vulnerabilidad (Castel, 1995). Respec…
Entre la exclusión y la violencia. Las mujeres institucionalizadas en los centros de protección de mujeres de la Comunidad Valenciana
2013
El objeto de estudio de esta tesis doctoral son las mujeres inmersas en procesos de exclusión social institucionalizadas en los centros de protección de mujeres de la Comunidad Valenciana. La investigación tiene una profundidad temporal de unos 30 años. Se extiende desde la transferencia de las competencias estatales en materia de protección a la mujer a la mencionada Comunidad Autónoma hasta el momento actual. La estrategia general y las más importantes técnicas de investigación utilizadas en este trabajo son de índole cualitativa. Así, se ha efectuado una amplia observación participante, entrevistas individuales y grupales a informantes clave y entrevistas en profundidad que, junto con lo…