Search results for "symmetry"
showing 10 items of 3576 documents
Theoretical and computational studies of magnetic anisotropy and exchange coupling in molecular systems
2018
The field of molecular magnetism studies the magnetic properties of molecular systems as opposed to conventional metal-based magnets. The high chemical modifiability of the constituting molecules makes such materials highly versatile, and the small size of the building blocks leads to the rise of various quantum mechanical phenomena, such as tunneling and entanglement. These phenomena can then be further utilized in the construction of nanoscale quantum devices. This dissertation describes computational and theoretical studies in the field of molecular magnetism using state-of-the-art quantum chemical methods based on ab initio multireference approaches and broken symmetry density functional t…
Measurement of the average shape of longitudinal profiles of cosmic-ray air showers at the Pierre Auger Observatory
2019
The profile of the longitudinal development of showers produced by ultra-high energy cosmic rays carries information related to the interaction properties of the primary particles with atmospheric nuclei. In this work, we present the first measurement of the average shower profile in traversed atmospheric depth at the Pierre Auger Observatory. The shapes of profiles are well reproduced by the Gaisser-Hillas parametrization within the range studied, for E>10 17.8 eV .A detailed analysis of the systematic uncertainties is performed using ten years of data and a full detector simulation. The average shape is quantified using two variables related to the width and asymmetry of the profile, and …
Modele ustrojowe opozycji parlamentarnej w strukturze systemu politycznego Zjednoczonego Królestwa, Republiki Federalnej Niemiec i V Republiki Francu…
2017
The right to oppose the current government is an indispensable element of the pluralist system of liberal democracy. A parliamentary opposition may function in various organisational forms. It comprises political groups and factions which do not participate in the formation of the government, adopt a critical attitude towards the programme of the executive branch, and offer alternative solutions with respect to programmes and the staffi ng of ministerial positions. This study of the three cases of the United Kingdom, Germany and France confi rms that, besides the common attribute of representing a political orientation different from that of the current government, an opposition is distingu…
Supersymmetry searches in ATLAS at the LHC
2017
La Física de Partículas es la rama de la ciencia que estudia los componentes elementales del Universo y sus interacciones fundamentales. La teoría de las partículas fundamentales y sus interacciones es conocida como el Modelo Estándar (SM). Éste proporciona la descripción más precisa, hasta la fecha, de la fenomenología de la Física de Partículas Elementales. Su validez ha sido demostrada hasta escalas de energía del orden de TeV. No obstante, el SM no se considera la teoría fundamental definitiva ya que existe evidencia de Nueva Física imposible de describir con el SM como la existencia de Materia Oscura, la asimetría entre materia y antimateria del Universo, las masas de los neutrinos o e…
Assessment of the lower limb biomechanics in patients after tibiofibular syndesmosis injury treatment
2021
Purpose: There is no consensus as to the number of bone cortices engaged in tibiofibular syndesmosis treatment. The purpose of our study was to assess the weight distribution on the lower limbs after tricortical or quadricortical syndesmosis fixation and different timing of screw removal. Methods: A total of 55 patients who underwent treatment for acute tibiofibular syndesmosis injury were analyzed in this study. The Zebris pedobarographic platform was used to measure the distribution of body weight on the lower limbs. The study population was stratified by the time to syndesmotic screw removal (8–15 weeks versus 16–22 weeks) and the number of bone cortices involved in fixation (three [tric…
A first-order phase transition for pulsar surface
2012
In this paper, we explain the existence of a possible first-order phase transition that may occur over the external solid crust of a pulsar, by means of an interpretation of a particular formal model (drawn from Theoretical Astrophysics) whose thermodynamical phenomenology shows a possible first-order phase transition (according to Landau’s Phenomenological Theory).
Dark matter and baryogenesis in Higgs portal models
2016
This work focuses on two of the main issues in current understanding of particle physics described by the Standard Model. The Standard Model, despite of its success, is not complete. Existence of dark matter has been clearly verified, but its nature is unknown. Also, the baryon asymmetry in the Universe hints that the Standard Model has to be extended. In this thesis we study Higgs portal models which both contain dark matter candidates, and can provide for a successful production of the baryon asymmetry.
Comparing proton momentum distributions in A = 2 and 3 nuclei via 2H 3H and 3He (e,e′p) measurements
2019
We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ …
Radial symmetry of p-harmonic minimizers
2017
"It is still not known if the radial cavitating minimizers obtained by Ball [J.M. Ball, Discontinuous equilibrium solutions and cavitation in nonlinear elasticity, Phil. Trans. R. Soc. Lond. A 306 (1982) 557--611] (and subsequently by many others) are global minimizers of any physically reasonable nonlinearly elastic energy". The quotation is from [J. Sivaloganathan and S. J. Spector, Necessary conditions for a minimum at a radial cavitating singularity in nonlinear elasticity, Ann. Inst. H. Poincare Anal. Non Lineaire 25 (2008), no. 1, 201--213] and seems to be still accurate. The model case of the $p$-harmonic energy is considered here. We prove that the planar radial minimizers are indee…
economics in the mirror of the financial crisis
2011
The structure of the Chapter is as follows. In Section 2 I discuss some of the factors that may have played a role in causing the crisis and emphasise that supporters of different economic theories will assign different weights to each factor in their analyses. As a consequence, suggested economic policies are highly sensitive to the economic theory employed in evaluating the set of causes. In Section 3 I seek to defend economists from the common charge that their inability to foresee the crisis is a clear sign of the lack of scientific status of their discipline. In my view, the main liability of mainstream economics lies elsewhere, in its excessive trust on the self-equilibrating mechanis…