Quantum Quench from a Thermal Initial State

We consider a quantum quench in a system of free bosons, starting from a thermal initial state. As in the case where the system is initially in the ground state, any finite subsystem eventually reaches a stationary thermal state with a momentum-dependent effective temperature. We find that this can, in some cases, even be lower than the initial temperature. We also study lattice effects and discuss more general types of quenches.Comment: 6 pages, 2 figures; short published version, added references, minor change

Dynamics of a Quantum Phase Transition and Relaxation to a Steady State

We review recent theoretical work on two closely related issues: excitation of an isolated quantum condensed matter system driven adiabatically across a continuous quantum phase transition or a gapless phase, and apparent relaxation of an excited system after a sudden quench of a parameter in its Hamiltonian. Accordingly the review is divided into two parts. The first part revolves around a quantum version of the Kibble-Zurek mechanism including also phenomena that go beyond this simple paradigm. What they have in common is that excitation of a gapless many-body system scales with a power of the driving rate. The second part attempts a systematic presentation of recent results and conjectures on apparent relaxation of a pure state of an isolated quantum many-body system after its excitation by a sudden quench. This research is motivated in part by recent experimental developments in the physics of ultracold atoms with potential applications in the adiabatic quantum state preparation and quantum computation.Comment: 117 pages; review accepted in Advances in Physic

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Study of the K*/K Yield Ratio in Relativistic Heavy Ion Collisions

No presente trabalho estudamos as abundâncias dos mésons K* e K em colisões de íons pesados relativísticos e como elas mudam durante a fase de gás hadrônico que aparece após o resfriamento do plasma de quarks e glúons. Como fatores que potencialmente influenciam a abundâncias destes mésons, foram explorados: a dinâmica microscópica, ou seja, as interações que ocorrem no gás de hádrons; a temperatura de freeze-out térmico, na qual o sistema deixa de interagir e as abundâncias são fixadas e a evolução da temperatura do sistema conforme este se expande. Por fim, comparamos os valores obtidos com valores experimentais da razão K*/K medidos no experimento ALICE do LHC.In this work, we present a study of the abundances of K* and K mesons in heavy ion collision and how they are affected by the hadron gas phase that arises once the initial quark gluon plasma has cooled enough. We explore the influence of three main factors over these abundances: the microscopic dynamics that describe the mesons\' interactions in the medium; the kinetic freeze-out temperature at which the interactions cease and the abundances are fixed; and the temperature evolution of the system as it expands. Finally, we present a comparison between the results from these calculations and the observed yield ratios measured in LHC\'s ALICE experiment

Chronique "Conseil européen - Conseil de l'UE", sous la direction de Rostane Mehdi

International audienc

A recurrent point mutation in PRKCA is a hallmark of chordoid gliomas

International audienceChordoid glioma (ChG) is a characteristic, slow growing, and well-circumscribed diencephalic tumor, whose mutational landscape is unknown. Here we report the analysis of 16 ChG by whole-exome and RNA-sequencing. We found that 15 ChG harbor the same PRKCA$^{D463H}$ mutation. PRKCA encodes the Protein kinase C (PKC) isozyme alpha (PKC$\alpha$) and is mutated in a wide range of human cancers. However the hot spot PRKCA$^{D463H}$ mutation was not described in other tumors. PRKCA$^{D463H}$ is strongly associated with the activation of protein translation initiation (EIF2) pathway. PKC$\alpha$$^{D463H}$ mRNA levels are more abundant than wild-type PKC$\alpha$ transcripts, whilePKC$\alpha$$^{D463H}$ is less stable than the PCK$\alpha$WT protein. Compared to PCK$\alpha$WT, the PKC$\alpha$$^{D463H}$ protein is depleted from the cell membrane. The PKC$\alpha$$^{D463H}$ mutant enhances proliferation of astrocytes and tanycytes, the cells of origin of ChG. In conclusion, our study identifies the hallmark mutation for chordoid gliomas and provides mechanistic insights on ChG oncogenesis