51,242 research outputs found
dilemas Ă©ticos
Ficha de anĂĄlisis de dilemas Ă©ticos en Trabajo SocialSe presenta una ficha con los diferentes parĂĄmetros necesarios para el abordaje y anĂĄlisis de los dilemas Ă©ticos que se presentan en la intervenciĂłn social
Hamiltonisation, measure preservation and first integrals of the multi-dimensional rubber Routh sphere
We consider the multi-dimensional generalisation of the problem of a sphere,
with axi-symmetric mass distribution, that rolls without slipping or spinning
over a plane. Using recent results from Garc\'ia-Naranjo (arXiv: 1805:06393)
and Garc\'ia-Naranjo and Marrero (arXiv: 1812.01422), we show that the reduced
equations of motion possess an invariant measure and may be represented in
Hamiltonian form by Chaplygin's reducing multiplier method. We also prove a
general result on the existence of first integrals for certain Hamiltonisable
Chaplygin systems with internal symmetries that is used to determine conserved
quantities of the problem.Comment: 23 pages, 1 figure. Submitted to the special issue of Theor. Appl.
Mech. in honour of Chaplygin's 150th anniversar
ConversiĂłn hidrotermal de biomasa en bioproductos valiosos
Los procesos hidrotérmicos son una excelente alternativa para convertir desechos de biomasa en productos de alto valor energético. El alcance de este proyecto ofrece el estudio de 5 tipos de biomasa distintos: café, madera blanca, arroz, lignina y madera negra (Zilkha).
La reacciĂłn se llevĂł a cabo en un reactor continĂșo cambiando las condiciones de presiĂłn y temperatura. El cafĂ© demostrĂł ser la materia primar de mayor rendimiento, alcanzando valores de hasta el 70% y, por el contrario, la lignina alcanzĂł muy bajos rendimientos, no sobrepasando el 13%.
Para analizar el bioproducto solido obtenido se realizĂł un anĂĄlisis termogravimĂ©trico. A partir de estos datos, se propuso un nuevo mĂ©todo denominado âdesplazamientoâ que refleja las diferencias entre los perfiles del producto sĂłlido logrado y la biomasa no tratada.
TambiĂ©n se utilizaron tĂ©cnicas de HPLC y MALDI-TOF-MS que demostraron mayores concentraciones en los bioproductos lĂquidos obtenidos segĂșn aumentaba la temperatura de reacciĂłn.University of NottinghamGrado en IngenierĂa QuĂmic
Measuring dispersion in the context of ordered qualitative scales
ProducciĂłn CientĂficaThe main purpose of this contribution is to measure the dispersion associated with the different results of a variable when they form a set of linguistic terms obtained after examining different qualities of people, services, etc, ordered, but with a non-homogeneous and non-quantifiable distance between the linguistic terms.Ministerio de EconomĂa, Industria y Competitividad (project ECO2016-77900-P
The impact of student loans on educational attainment: the case of a program at the pontifical catholic university of Peru
During the past decades, the Pontifical Catholic University of Peru (known as PUCP) has been giving student loans to some of its students with satisfactory academic performance but who face certain economic problems which might interrupt their studies. Although this program was created more than forty years ago, its results have not been rigorously evaluated. This document attempts to assess to what extent the program has benefited students. Because the collected data come from academic and social records, the completion of this task requires using modern techniques specifically designed to work with non experimental data. After estimating by propensity score matching with multiple treatments, I find a statistically significant impact of this program on the time a student employs to complete the course of study at PUCP (measured in semesters) only when a student was awarded with a loan for 6 semesters or more. That effect is not significantly different from zero when the loan lasts less than 6 semesters. Similar results were found when I analyzed the impact on the probability of degree completion of student loans, where students with loan were more likely to meet all graduation requirements by 6 years and a half after they start studying at PUCP. Again this effect was significant only when the student participates in the program for six semesters or more. However, the impact on that probability was small.Student Loans, Matching, Treatment Effect
Gauge Transformations, Twisted Poisson Brackets and Hamiltonization of Nonholonomic Systems
In this paper we study the problem of Hamiltonization of nonholonomic systems
from a geometric point of view. We use gauge transformations by 2-forms (in the
sense of Severa and Weinstein [29]) to construct different almost Poisson
structures describing the same nonholonomic system. In the presence of
symmetries, we observe that these almost Poisson structures, although gauge
related, may have fundamentally different properties after reduction, and that
brackets that Hamiltonize the problem may be found within this family. We
illustrate this framework with the example of rigid bodies with generalized
rolling constraints, including the Chaplygin sphere rolling problem. We also
see how twisted Poisson brackets appear naturally in nonholonomic mechanics
through these examples
Hitchin-Kobayashi correspondence, quivers, and vortices
A twisted quiver bundle is a set of holomorphic vector bundles over a complex
manifold, labelled by the vertices of a quiver, linked by a set of morphisms
twisted by a fixed collection of holomorphic vector bundles, labelled by the
arrows. When the manifold is Kaelher, quiver bundles admit natural
gauge-theoretic equations, which unify many known equations for bundles with
extra structure. In this paper we prove a Hitchin--Kobayashi correspondence for
twisted quiver bundles over a compact Kaehler manifold, relating the existence
of solutions to the gauge equations to a stability criterion, and consider its
application to a number of situations related to Higgs bundles and dimensional
reductions of the Hermitian--Einstein equations.Comment: 28 pages; larger introduction, added references for the introduction,
added a short comment in Section 1, typos corrected, accepted in Comm. Math.
Phy
Past observable dynamics of a continuously monitored qubit
Monitoring a quantum observable continuously in time produces a stochastic
measurement record that noisily tracks the observable. For a classical process
such noise may be reduced to recover an average signal by minimizing the mean
squared error between the noisy record and a smooth dynamical estimate. We show
that for a monitored qubit this usual procedure returns unusual results. While
the record seems centered on the expectation value of the observable during
causal generation, examining the collected past record reveals that it better
approximates a moving-mean Gaussian stochastic process centered at a distinct
(smoothed) observable estimate. We show that this shifted mean converges to the
real part of a generalized weak value in the time-continuous limit without
additional postselection. We verify that this smoothed estimate minimizes the
mean squared error even for individual measurement realizations. We go on to
show that if a second observable is weakly monitored concurrently, then that
second record is consistent with the smoothed estimate of the second observable
based solely on the information contained in the first observable record.
Moreover, we show that such a smoothed estimate made from incomplete
information can still outperform estimates made using full knowledge of the
causal quantum state.Comment: 11 pages, 4 figure
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