Band and correlated insulators of cold fermions in a mesoscopic lattice

We investigate the transport properties of neutral, fermionic atoms passing through a one-dimensional quantum wire containing a mesoscopic lattice. The lattice is realized by projecting individually controlled, thin optical barriers on top of a ballistic conductor. Building an increasingly longer lattice, one site after another, we observe and characterize the emergence of a band insulating phase, demonstrating control over quantum-coherent transport. We explore the influence of atom-atom interactions and show that the insulating state persists as contact interactions are tuned from moderately to strongly attractive. Using bosonization and classical Monte-Carlo simulations we analyze such a model of interacting fermions and find good qualitative agreement with the data. The robustness of the insulating state supports the existence of a Luther-Emery liquid in the one-dimensional wire. Our work realizes a tunable, site-controlled lattice Fermi gas strongly coupled to reservoirs, which is an ideal test bed for non-equilibrium many-body physics.Comment: 8 + 10 pages, 5 + 7 figure

Quantized conductance through a spin-selective atomic point contact

We implement a microscopic spin filter for cold fermionic atoms in a quantum point contact (QPC) and create fully spin-polarized currents while retaining conductance quantization. Key to our scheme is a near-resonant optical tweezer inducing a large effective Zeeman shift inside the QPC while its local character limits dissipation. We observe a renormalization of this shift due to interactions of a few atoms in the QPC. Our work represents the analog of an actual spintronic device and paves the way to studying the interplay between spin-splitting and interactions far from equilibrium.Comment: see also companion paper arXiv:1907.0643

POSITIONEN: Kinderrechte in der Vollzeitpflege – Reformbedarf zur Verwirklichung von Schutzkonzepten in der Infrastruktur der Pflegekinderhilfe

Das Team "Foster Care" benennt in diesem Positionspapier wichtige Forderungen für die SGB VIII Reform in Bezug auf die Umsetzung von Schutzkonzepten in der Pflegekinderhilfe

Monitoring and modelling of debris-flow erosion in the Rebaixader catchment (Pyrenees, Spain)

Debris flow and other torrential processes can entrain large volumes of sediments along their runout path. Since the debris-flow hazard strongly depends on the volume, the research on the entrainment is relevant and has been analysed by multiple approaches in the past. In this study, the erosion volume due to torrential processes has been monitored in the Rebaixader catchment (Spain) by digital elevation models obtained from Uncrewed Aerial Vehicle (UAV) surveys and by the instrumental monitoring system installed in the channel reach. In addition, the entrainment of debris flows has been modelled by the numerical code FLATModel. The results of both approaches show that debris flows in the studied catchment are characterised by a large entrainment and the assumption of landslide-triggered debris flows has been refuted. Important erosion in the gullies of the initiation area has been detected by the UAV data and the numerical modelling. An average annual erosion volume of about 6100 m3/y has been determined

Novel Structurally Designed Vaccine for S. aureus α-Hemolysin: Protection against Bacteremia and Pneumonia

Staphylococcus aureus (S. aureus) is a human pathogen associated with skin and soft tissue infections (SSTI) and life threatening sepsis and pneumonia. Efforts to develop effective vaccines against S. aureus have been largely unsuccessful, in part due to the variety of virulence factors produced by this organism. S. aureus alpha-hemolysin (Hla) is a pore-forming toxin expressed by most S. aureus strains and reported to play a key role in the pathogenesis of SSTI and pneumonia. Here we report a novel recombinant subunit vaccine candidate for Hla, rationally designed based on the heptameric crystal structure. This vaccine candidate, denoted AT-62aa, was tested in pneumonia and bacteremia infection models using S. aureus strain Newman and the pandemic strain USA300 (LAC). Significant protection from lethal bacteremia/sepsis and pneumonia was observed upon vaccination with AT-62aa along with a Glucopyranosyl Lipid Adjuvant-Stable Emulsion (GLA-SE) that is currently in clinical trials. Passive transfer of rabbit immunoglobulin against AT-62aa (AT62-IgG) protected mice against intraperitoneal and intranasal challenge with USA300 and produced significant reduction in bacterial burden in blood, spleen, kidney, and lungs. Our Hla-based vaccine is the first to be reported to reduce bacterial dissemination and to provide protection in a sepsis model of S. aureus infection. AT62-IgG and sera from vaccinated mice effectively neutralized the toxin in vitro and AT62-IgG inhibited the formation of Hla heptamers, suggesting antibody-mediated neutralization as the primary mechanism of action. This remarkable efficacy makes this Hla-based vaccine a prime candidate for inclusion in future multivalent S. aureus vaccine. Furthermore, identification of protective epitopes within AT-62aa could lead to novel immunotherapy for S. aureus infection

Impact de la mémoire de travail sur la suppression de stimuli menaçants

Selon l'hypothèse de la capture attentionnelle de la menace, les stimuli liés à la colère ont une capture attentionnelle élevée. De ce fait, des stimuli non pertinents mais menaçants, comme des visages de colère, interfèrent davantage lors d'une tâche de recherche visuelle. Ce biais attentionnel vers la menace est décrit selon la théorie par un processus bottom-up, c'est-à-dire automatique et involontaire. Parallèlement à cela, le processus top-down décrit que l'attention peut être guidée de manière volontaire selon notamment le contenu retenu en mémoire de travail. Or, certaines recherches récentes ont démontré que la capture par des visages menaçants pouvait être en lien avec l'information en mémoire de travail. Ainsi, un distracteur non pertinent ne capture donc pas de manière systématique l'attention, mais peut être activement supprimé et le contenu de la mémoire de travail influence donc la capture attentionnelle. Par exemple, Sawaki a démontré une suppression de l'attention, en direction d'un distracteur de la même couleur que l'objet retenu en mémoire de travail. Afin de déterminer si des stimuli menaçants peuvent être également activement supprimés, nous avons adapté le paradigme de Sawaki en remplaçant les pastilles de couleurs par des visages valencés émotionnellement (Joie et Colère). Nos résultats électrophysiologiques ne révèlent aucune suppression de l'attention (PD), mais une capture de l'attention (N2pc). Bien, qu'aucune différence significative n'a été retrouvée entre les visages de joie et colère, contrecarrant les théories du biais attentionnel vers la menace (Expérience n° 1), l'Expérience n° 2 démontre que la N2pc est absente si la tâche implique de garder en mémoire des stimuli non-visages. Nos résultats apportent donc de nouvelles preuves en faveur de la théorie de la capture attentionnelle contingente.</p

Breakdown of the Wiedemann–Franz law in a unitary Fermi gas

ISSN:0027-8424ISSN:1091-649

Quantized conductance through a dissipative atomic point contact

ISSN:1094-1622ISSN:0556-2791ISSN:1050-294

POSITIONEN: Kinderrechte in der Vollzeitpflege – Reformbedarf zur Verwirklichung von Schutzkonzepten in der Infrastruktur der Pflegekinderhilfe

Das Team "Foster Care" benennt in diesem Positionspapier wichtige Forderungen für die SGB VIII Reform in Bezug auf die Umsetzung von Schutzkonzepten in der Pflegekinderhilfe

Wir waren eine glueckliche Familie : Die Familie Horwitz aus Harburg (1885-2007).

A collection of articles, clippings, and photographs compiled by seven high school students from Harburg about a Jewish family that used to live in that town.digitizedLotte BlausteinCelia J. LeeCelia J. Lee2008050