134 research outputs found
Element history of the Laplace resonance: A dynamical approach
No full textContext. We consider the three-body mean motion resonance defined by the Jovian moons Io, Europa, and Ganymede, which is commonly known as the Laplace resonance. In terms of the moons' mean longitudes lambda(1) (Io), lambda(2) (Europa), and lambda(3) (Ganymede), this resonance is described by the librating argument phi(L) lambda(1) - 3 lambda(2) + 2 lambda(3)( )approximate to 180 degrees, which is the sum of phi(12) lambda(1) - 2 lambda(2) + pi(2) approximate to 180 degrees and phi(23) lambda(2) - 2 lambda(3) pi(2)( )approximate to 0 degrees, where pi(2) denotes Europa's longitude of perijove.Aims. In particular, we construct approximate models for the evolution of the librating argument phi(L) over the period of 100 yr, focusing on its principal amplitude and frequency, and on the observed mean motion combinations n(1) - 2n(2) and n(2) - 2n(3) associated with the quasi-resonant interactions above.Methods. First, we numerically propagated the Cartesian equations of motion of the Jovian system for the period under examination, and by comparing the results with a suitable set of ephemerides, we derived the main dynamical effects on the target quantities. Using these effects, we built an alternative Hamiltonian formulation and used the normal forms theory to precisely locate the resonance and to semi-analytically compute its main amplitude and frequency.Results. From the Cartesian model we observe that on the timescale considered and with ephemerides as initial conditions, both phi(L) and the diagnostics n(1) - 2n(2) and n(2) - 2n(3) are well approximated by considering the mutual gravitational interactions of Jupiter and the Galilean moons (including Callisto), and the effect of Jupiter's J(2) harmonic. Under the same initial conditions, the Hamiltonian formulation in which Callisto and J(2) are reduced to their secular contributions achieves larger errors for the quantities above, particularly for phi(L) . By introducing appropriate resonant variables, we show that these errors can be reduced by moving in a certain action-angle phase plane, which in turn implies the necessity of a tradeoff in the selection of the initial conditions.Conclusions. In addition to being a good starting point for a deeper understanding of the Laplace resonance, the models and methods described are easily generalizable to different types of multi-body mean motion resonances. Thus, they are also prime tools for studying the dynamics of extrasolar systems
The dynamics of the de Sitter resonance
No full textWe study the dynamics of the de Sitter resonance, namely the stable equilibrium configuration of the first three Galilean satellites. We clarify the relation between this family of configurations and the more general Laplace resonant states. In order to describe the dynamics around the de Sitter stable equilibrium, a one-degree of freedom Hamiltonian normal form is constructed and exploited to identify initial conditions leading to the two families.
The normal form Hamiltonian is used to check the accuracy in the location of the equilibrium positions. Besides, it gives a measure of how sensitive it is with respect to the different perturbations acting on the system. By looking at the phase-plane of the normal form, we can identify a \sl Laplace-like \rm configuration, which highlights many substantial aspects of the observed one
The dynamics of Laplace-like resonances
No full textThe three inner Galilean satellites of Jupiter-Io, Europa, and Ganymede-are observed to move in a particular dynamical configuration, which is commonly known as the Laplace resonance. These satellites are characterized by a 2:1 ratio between the mean longitudes of Io-Europa and Europa-Ganymede. Another dynamical configuration, known as the de Sitter resonance, occurs when the longitude of Ganymede is fixed, instead of rotating like in the Laplace resonance. Besides studying the Laplace and de Sitter resonances, we also consider their generalizations to the case in which the mean longitudes of the first two satellites are in a ratio k:j, while those of the second and third satellites are in a ratio m:n with k,j,m,n∈Z+ and |j-k|, |n-m|≤2. We derive a model apt to describe such resonant configurations. We make an extensive study of the structural stability of the resonances; we show that the libration of the Laplace resonant angle is deeply affected by small variations of some quantities, most notably the semimajor axes and the oblateness. A remarkable result is that in several cases, the standard Laplace resonance of the Galilean satellites displays a regular behavior in comparison to other resonances characterized by different mean longitude ratios, which instead show a rather chaotic behavior even on short time scales. This result provides a motivation to support why the Galilean satellites are found in the actual Laplace resonance
Centro per la qualificazione di sistemi di navigazione Galileo per UAV (Unmanned Aerial Vehicle): Studio di fattibilità
No full textRapporto finale su contratto di ricerc
Phytoplankton abundance in surface water in October 1997, Paita, Peru
No full textN=none, R=rare, F=few, C=common, A=abundan
Phytoplankton abundance in surface water in October 1996, Paita, Peru
No full textN=none, R=rare, F=few, C=common, A=abundan
Absentismo y estrés laboral en trabajadores del Hospital Nuestra Señora las Mercedes- Paita,2023
No full textEsta investigación se realizó con la finalidad de determinar la correlación que existe
entre el Absentismo y estrés laboral en trabajadores del Hospital Nuestra Señora
de las Mercedes, Paita.
El estudio fue de tipo básico y de diseño no experimental de corte transversal. La
muestra estuvo conformada por 260 colaboradores de un nosocomio en la provincia
de Paita, en un intervalo de 25 a 60 años, el tipo de muestreo fue no probabilístico.
Aplicando como instrumento de recolección de datos, Encuesta de Absentismo
Jiménez, F. (2014) que fue adaptado por Velásquez K. (2019). Por otro lado, el
cuestionario de estrés laboral Castillo (2017). Así mismo para el análisis de datos
se utilizó el coeficiente de correlación de Rho de Spearman. Obteniendo como
resultados que existe correlación significativa baja entre la variable Absentismo y la
variable estrés laboral, con (.035) de significancia correlativa, evidenciando que se
anula la hipótesis planteada. En cuanto a las dimensiones de Factores externos de
absentismo laboral, específicamente en el indicador de agotamiento emocional, con
estrés laboral, se evidenció que existe correlación significativa (.153), determinando
correlación significativa
Estudio comparativo del clima laboral en la sede central y las jefaturas zonales de Piura, Talara y Paita- El Arenal de la EPS GRAU SA
No full textEn el presente estudio se determinan las diferencias significativas del Clima Laboral
entre la Sede Central y las Jefaturas Zonales de Piura, Talara Y Paita- El Arenal de la
EPS GRAU SA. Para determinar la muestra, se utilizo un muestreo intencional
obteniéndose una muestra de 219 trabajadores(39 de la Sede Central, 66 de la Jefatura
Zonal Piura, 45 de la Jefatura Zonal Paita- El Arenal y 69 de la Jefatura Zonal Talara).
Se utilizó como instrumento la Escala de Clima Laboral de Sonia Palma CL SPC la
cual esta compuesta por cinco factores: Autorrealización, Involucramiento laboral,
Supervisión, Comunicación y Condiciones laborales. Se hicieron comparaciones entre
estos factores, así como también de las variables edad, género, grado de instrucción y
tiempo de Servicio.
Al procesar la información, solo se encontraron diferencias significativas (F> 3.98) en
el factor II: Involucramiento Laboral y en el factor IV: Comunicación
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