The classical limit of the time dependent Hartree-Fock equation. I. The Weyl symbol of the solution

We study the time evolution of the Weyl symbol of a solution of the time dependent Hartree Fock equation, assuming that for t=0, it has a Weyl symbol which is integrable in the phase space, such as all its derivatives. We prove that the solution has the same property for all t, and we give an asymptotic expansion, in L1 sense, of this Weyl symbol

Race, Ethnicity, and American Views of Climate Change

Asian, Hispanic, and Black Americans are more likely to view climate change as a threat than Americans as a whole, data show.In the United States, definitions of national security threats are shifting, highly politicized, and closely tied to identity. At the same time, the US is more racially diverse than at any time in its past. To better understand how this diversity feeds into threat perception, the Chicago Council on Global Affairs and the New America Foundation have partnered to conduct novel research on the views of white, Black, Asian, Hispanic, and Native Americans as part of the 2022 Chicago Council Survey

Parler and the Road to the Capitol Attack: Investigating Alt-Tech Ties to January 6

The January 6, 2021 mob assault on the U.S. Capitol exposed deep fissures between Americans and shook the very foundations of the country. The violence that day and the tech industry's response to the tsunami of polarizing content triggered a major public debate over how social media and tech companies manage their platforms and services and the impact of content moderation policies on polarization, extremism, and political violence in the United States. That debate is also now playing out in Congress where the House Select Committee to Investigate the January 6th Attack on the United States Capitol is now underway. One big question is: How did niche social media sites geared toward far-right audiences, like Parler, contribute to polarization around the 2020 presidential election and to what extent did Parler and other platforms factor into the January 6 attack? The first in a series of investigations into the impact of the alt-tech movement on U.S. national security, this report provides an initial snapshot of observations culled from an ongoing analysis of open source data related to the Capitol attack.Based, in part, on an early assessment of a cache of an estimated 183 million Parler posts publicly archived after Parler was temporarily deplatformed, the analysis in this report offers unique insights into online and offline early warning signs of the potential for election-related violence in the year-long run up to the Capitol attack. On the streets and online, the networked effects of poor platform governance across the internet during the 2020 presidential election were notable on mainstream and fringe social media sites. Nevertheless, the combined impact of Parler's loose content moderation scheme as well as data-management practices and platform features—either by design or neglect, or both—may have made the social media startup especially vulnerable to strategic influence campaigns that relied heavily on inauthentic behavior like automated content amplification and deceptive techniques like astroturfing

The Human beyond Digitalization: Rethinking workspaces, skills, and HR practices

The aim of the Les Cahiers du Digital collection, published by the Digital Lab of HEC-Liège, is to enrich the teaching provided at HEC Liège thanks to the contribution of experts who possess proven field knowledge on key topics related to digital transformation. Three LENTIC researchers (Marine Franssen, Grégory Jemine, Giseline Rondeaux) have collaborated in the writing of the third issue of this collection, in which they share their expertise in the field of digitalization in human resources.La collection Les Cahiers du Digital, du Digital Lab d’HEC-Liège, a pour but d’enrichir les enseignements prodigués au sein de HEC Liège, grâce à la contribution d’experts qui détiennent une connaissance de terrain reconnue sur des sujets phares liés à la transformation numérique. Trois chercheurs du LENTIC (Marine Franssen, Grégory Jemine, Giseline Rondeaux) ont collaborés à l’écriture du troisième numéro de cette collection, dans lequel ils partagent leurs expertises en matière de digitalisation dans le domaine des ressources humaines

Design, construction, and quality tests of the large Al-alloy mandrels for the CMS coil

The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. Almost all large indirectly cooled solenoids constructed to date (e.g., Zeus, Aleph, Delphi, Finuda, Babar) comprise Al-alloy mandrels fabricated by welding together plates bent to the correct radius. The external cylinder of CMS will consist of five modules having an inner diameter of 6.8 m, a thickness of 50 mm and an individual length of 2.5 m. It will be manufactured by bending and welding thick plates (75 mm) of the strain hardened aluminum alloy EN AW-5083-H321. The required high geometrical tolerances and mechanical strength (a yield strength of 209 MPa at 4.2 K) impose a critical appraisal of the design, the fabrication techniques, the welding procedures and the quality controls. The thick flanges at both ends of each module will be fabricated as seamless rolled rings, circumferentially welded to the body of the modules. The developed procedures and manufacturing methods will be validated by the construction of a prototype mandrel of full diameter and reduced length (670 mm). (7 refs)

Semiclassical approximations for Hamiltonians with operator-valued symbols

We consider the semiclassical limit of quantum systems with a Hamiltonian given by the Weyl quantization of an operator valued symbol. Systems composed of slow and fast degrees of freedom are of this form. Typically a small dimensionless parameter $\varepsilon\ll 1$ controls the separation of time scales and the limit $\varepsilon\to 0$ corresponds to an adiabatic limit, in which the slow and fast degrees of freedom decouple. At the same time $\varepsilon\to 0$ is the semiclassical limit for the slow degrees of freedom. In this paper we show that the $\varepsilon$-dependent classical flow for the slow degrees of freedom first discovered by Littlejohn and Flynn, coming from an \epsi-dependent classical Hamilton function and an $\varepsilon$-dependent symplectic form, has a concrete mathematical and physical meaning: Based on this flow we prove a formula for equilibrium expectations, an Egorov theorem and transport of Wigner functions, thereby approximating properties of the quantum system up to errors of order $\varepsilon^2$. In the context of Bloch electrons formal use of this classical system has triggered considerable progress in solid state physics. Hence we discuss in some detail the application of the general results to the Hofstadter model, which describes a two-dimensional gas of non-interacting electrons in a constant magnetic field in the tight-binding approximation.Comment: Final version to appear in Commun. Math. Phys. Results have been strengthened with only minor changes to the proofs. A section on the Hofstadter model as an application of the general theory was added and the previous section on other applications was remove

Development and Coil Fabrication Test of the Nb3Sn Dipole Magnet PRESCA2

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