17,234 research outputs found
Constant of Motion for several one-dimensional systems and outlining the problem associated with getting their Hamiltonians
The constants of motion of the following systems are deduced: a relativistic
particle with linear dissipation, a no-relativistic particle with a time
explicitly depending force, a no-relativistic particle with a constant force
and time depending mass, and a relativistic particle under a conservative force
with position depending mass. The problem of getting the Hamiltonian for these
systems is determined by getting the velocity as an explicit function of
position and generalized linear momentum, and this problem can be solved a
first approximation for the first above system.Comment: 15 pages, Te
Inter-band B(E2) transition strengths in odd-mass heavy deformed nuclei
Inter-band B(E2) transition strengths between different normal parity bands
in 163Dy and 165Er are described using the pseudo-SU(3) model. The Hamiltonian
includes Nilsson single-particle energies, quadrupole-quadrupole and pairing
interactions with fixed, parametrized strengths, and three extra rotor terms
used to fine tune the energy spectra. In addition to inter-band transitions,
the energy spectra and the ground state intra-band B(E2) strengths are
reported. The results show the pseudo-SU(3) shell model to be a powerful
microscopic theory for a description of the normal parity sector in heavy
deformed odd-A nuclei.Comment: 4 figures, 2 table
MODELO BIDIMENSIONAL DE RIESGOS DEL MANTENIMIENTO DE SISTEMAS INTEGRADOS DE GESTIÓN (ERP)
La adopción y expansión de las Tecnologías de la Información y la Comunicación en el ámbito empresarial se está produciendo a gran velocidad. De la mano de las más innovadoras TIC y de los sistemas informáticos, surgen y se desarrollan los sistemas ERP. Éstos han sido implantados por empresas de todo el mundo. Tras su implantación, comienza su mantenimiento. Para que el resultado de estos proyectos sea satisfactorio, los riesgos que lo afectan tienen que ser gestionados. Una pobre gestión de estos riesgos, con frecuencia origina fallos en el sistema, lo que hace que las compañías tengan que asumir altas pérdidas. Para gestionar adecuadamente los riesgos, los profesionales deben comenzar identificándolos y clasificándolos. Para apoyar su labor, hemos realizado un estudio formal de los riesgos que afectan al mantenimiento de ERPs. La investigación finaliza con la elaboración de un Modelo de dos dimensiones compuesto por los riesgos identificados en la literatura
Efectos de salinidad de tres cultivares de mandarina en dos patrones diferentes
Citrus, one of the most important fruit crops in the world and also they are sensitive to salt stress. The negative effects of stresses often lead to reductions in fruit yield and quality. To assess the effects of salinity on some growth traits, a greenhouse test was performed with the cultivars ‘Mihowase’, ‘Primosole’ and ‘W. Murcott’ as grafted on ‘Cleopatra’ and ‘Swingle citrumelo’ as rootstocks. The experiment was conducted at the Agrarian Experimental Station of National Institution for Agricultural Innovation in Donoso-Huaral, ubicated 90 km north of Lima. The plants were irrigated with water plus NaCl with an Electrical Conductivity of 0.5 or 4.5 dS/m as salt stress. The variables under evaluation were leave losses, fresh and dry weight of stem, leaves and roots as well as relative water content in the plants. The results showed that the rootstocks ‘Cleopatra’ was more tolerant than ‘Swingle citrumelo’. The cultivars used as scions affected both rootstocks in all the evaluated traits being more notorious in the amount of feeding roots. Selection of mandarin trees for production shout take in consideration the combination scion/rootstock
Impaired Spatial Reorientation in the 3xTg-AD Mouse Model of Alzheimer's Disease.
In early Alzheimer's disease (AD) spatial navigation is impaired; however, the precise cause of this impairment is unclear. Recent evidence suggests that getting lost is one of the first impairments to emerge in AD. It is possible that getting lost represents a failure to use distal cues to get oriented in space. Therefore, we set out to look for impaired use of distal cues for spatial orientation in a mouse model of amyloidosis (3xTg-AD). To do this, we trained mice to shuttle to the end of a track and back to an enclosed start box to receive a water reward. Then, mice were trained to stop in an unmarked reward zone to receive a brain stimulation reward. The time required to remain in the zone for a reward was increased across training, and the track was positioned in a random start location for each trial. We found that 6-month female, but not 3-month female, 6-month male, or 12-month male, 3xTg-AD mice were impaired. 6-month male and female mice had only intracellular pathology and male mice had less pathology, particularly in the dorsal hippocampus. Thus, AD may cause spatial disorientation as a result of impaired use of landmarks
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