Data processing and online reconstruction

In the upcoming upgrades for Run 3 and 4, the LHC will significantly increase Pb--Pb and pp interaction rates. This goes along with upgrades of all experiments, ALICE, ATLAS, CMS, and LHCb, related to both the detectors and the computing. The online processing farms must employ faster, more efficient reconstruction algorithms to cope with the increased data rates, and data compression factors must increase to fit the data in the affordable capacity for permanent storage. Due to different operating conditions and aims, the experiments follow different approaches, but there are several common trends like more extensive online computing and the adoption of hardware accelerators. This paper gives an overview and compares the data processing approaches and the online computing farms of the LHC experiments today in Run 2 and for the upcoming LHC Run 3 and 4.Comment: 6 pages, 0 figures, contribution to LHCP2018 conferenc

Propiedad y libertad: una crítica a la teoría de la justicia de Hume desde el pensamiento de Simone de Beauvoir y una respuesta humeana

David Hume and Simone de Beauvoir agree that human beings have a great deal of control over their moral and political lives, which is well captured in Hume’s assertion that “mankind is an inventive species”. But Hume argues that the most important thing needed to settle our social lives and determine justice is the agreement on rules of property, while Beauvoir thinks that the rules of property will never be enough to establish the best life, but rather that we should be focusing on freedom. In this article we reconstruct Hume’s argument for property, then develop a Beauvoirian critique of Hume that brings out the weakness of any theory of property that does not prevent inequalities of property from interfering with freedom. And then we give the last word to a Humean response to Beauvoir that would insist that there can be no freedom but only violence without rules of property, which she ignores. Both thinkers appeal to humanity as an overriding goal, and perhaps that is the way to reconcile the two: we need both property and freedom to achieve our humanity.David Hume y Simone de Beauvoir están de acuerdo en que los seres humanos tienen un grado muy importante de control sobre sus vidas morales y políticas; lo que está muy bien captado en la afirmación de Hume de que “la humanidad es una especie inventiva”. Pero Hume argumenta que lo más importante a la hora de constituir nuestras vidas sociales y establecer la justicia es el acuerdo sobre las reglas de la propiedad, mientras que Beauvoir piensa que las reglas de propiedad nunca serán suficientes para establecer la vida mejor, sino que más bien deberíamos centrarnos en la libertad. En este artículo reconstruimos el argumento de Hume a favor de la propiedad, para desarrollar después una crítica basada en la perspectiva de Simone de Beauvoir que saca a la luz la debilidad de cualquier teoría de la propiedad que no evite que las desigualdades de propiedad interfieran con la libertad, Y después damos la última palabra a una respuesta humeana a Beauvoir que insistiría en que no puede haber libertad –sino solo violencia- sin reglas de propiedad, algo que ella ignora. Ambos pensadores recurren a la humanidad como el objetivo predominante, y quizás esta es la forma de reconciliarlos: necesitamos tanto de la propiedad como de la libertad para lograr nuestra humanidad

Full Configuration Interaction wave function as a formal solution to the Optimized Effective Potential and Kohn-Sham models in finite basis sets

Using finite basis sets, it is shown how to construct a local Hamiltonian, such that one of its infinitely many degenerate eigenfunctions is the ground state full configuration interaction (FCI) wave function in that basis set. Formally, the local potential of this Hamiltonian is the optimized effective potential and the exact Kohn-Sham potential at the same time, because the FCI wave function yields the exact ground-state density and energy. It is not the aim of this paper to provide a new algorithm for obtaining FCI wave functions. A new potential is the goal

Fixing the shadows while moving the gnomon

It is a common practice to fix a vertical gnomon and study the moving shadow cast by it. This shows our local solar time and gives us a hint regarding the season in which we perform the observation. The moving shadow can also tell us our latitude with high precision. In this paper we propose to exchange the roles and while keeping the shadows fixed on the ground we will move the gnomon. This lets us understand in a simple way the relevance of the tropical lines of latitude and the behavior of shadows in different locations. We then put these ideas into practice using sticks and threads during a solstice on two sites located on opposite sides of the Tropic of Capricorn.Comment: Published version available at http://cms.iafe.uba.ar/gangui/didaastro/#Publication

Combining Density Functional Theory and Density Matrix Functional Theory

We combine density-functional theory with density-matrix functional theory to get the best of both worlds. This is achieved by range separation of the electronic interaction which permits to rigorously combine a short-range density functional with a long-range density-matrix functional. The short-range density functional is approximated by the short-range version of the Perdew-Burke-Ernzerhof functional (srPBE). The long-range density-matrix functional is approximated by the long-range version of the Buijse-Baerends functional (lrBB). The obtained srPBE+lrBB method accurately describes both static and dynamic electron correlation at a computational cost similar to that of standard density-functional approximations. This is shown for the dissociation curves of the H$_{2}$, LiH, BH and HF molecules.Comment: 4 pages, 5 figure

Superconductivity in rubidium substituted Ba1-xRbxTi2Sb2O

We report on the synthesis and the physical properties of Ba1-xRbxTi2Sb2O (x < 0.4) by x-ray diffraction, SQUID magnetometery, resistivity and specific heat measurements. Upon hole doping by substituting Ba with Rb, we find superconductivity with a maximum Tc = 5.4 K. Simultaneously, the charge-density-wave (CDW) transition temperature is strongly reduced from T_CDW 55 K in the parent compound BaTi2Sb2O and seems to be suppressed for x > 0.2. The bulk character of the superconducting state for the optimally doped sample (x = 0.2) is confirmed by the occurrence of a well developed discontinuity in the specific heat at Tc, with \DeltaC/Tc = 22 mJ/mol K2, as well as a large Meissner-shielding fraction of approximately 40 %. The lower and the upper critical fields of the optimally doped sample (x = 0.2) are estimated to \mu0Hc1(0) = 3.8 mT and \mu0Hc2(0) = 2.3 T, respectively, indicating that these compounds are strongly type-II superconductors