Nagaoka ferromagnetism observed in a quantum dot plaquette

Engineered, highly-controllable quantum systems hold promise as simulators of emergent physics beyond the capabilities of classical computers. An important problem in many-body physics is itinerant magnetism, which originates purely from long-range interactions of free electrons and whose existence in real systems has been subject to debate for decades. Here we use a quantum simulator consisting of a four-site square plaquette of quantum dots to demonstrate Nagaoka ferromagnetism. This form of itinerant magnetism has been rigorously studied theoretically but has remained unattainable in experiment. We load the plaquette with three electrons and demonstrate the predicted emergence of spontaneous ferromagnetic correlations through pairwise measurements of spin. We find the ferromagnetic ground state is remarkably robust to engineered disorder in the on-site potentials and can induce a transition to the low-spin state by changing the plaquette topology to an open chain. This demonstration of Nagaoka ferromagnetism highlights that quantum simulators can be used to study physical phenomena that have not yet been observed in any system before. The work also constitutes an important step towards large-scale quantum dot simulators of correlated electron systems.Comment: This version: main (8 pages, 6 figures) + supplementary (15 pages, 8 figures

A capacitance spectroscopy-based platform for realizing gate-defined electronic lattices

Electrostatic confinement in semiconductors provides a flexible platform for the emulation of interacting electrons in a two-dimensional lattice, including in the presence of gauge fields. This combination offers the potential to realize a wide host of quantum phases. Here we present a measurement and fabrication scheme that builds on capacitance spectroscopy and allows for the independent control of density and periodic potential strength imposed on a two-dimensional electron gas. We characterize disorder levels and (in)homogeneity and develop and optimize different gating strategies at length scales where interactions are expected to be strong. A continuation of these ideas might see to fruition the emulation of interaction-driven Mott transitions or Hofstadter butterfly physics

Medial Patellofemoral Ligament Repair With Suture Tape Augmentation

The medial patellofemoral ligament (MPFL) is the main restraining force in the first 20° of flexion against lateral patellar displacement and is disrupted after patellar subluxation or dislocation. MPFL reconstruction is frequently performed when conservative management fails and the patient has recurrent patellar dislocations. However, a variety of complications have been reported in the literature with this procedure. Internal bracing with suture tape augmentation encourages healing and allows early mobilization. This article describes, with video illustration, MPFL repair with suture tape augmentation

Blocking entry of hepatitis B and D viruses to hepatocytes as a novel immunotherapy for treating chronic infections

Background. Chronic hepatitis B and D virus (HBV/HDV) infections can cause cancer. Current HBV therapy using nucleoside analogues (NAs) is life-long and reduces but does not eliminate the risk of cancer. A hallmark of chronic hepatitis B is a dysfunctional HBV-specific T-cell response. We therefore designed an immunotherapy driven by naive healthy T cells specific for the HDV antigen (HDAg) to bypass the need for HBV-specific T cells in order to prime PreS1-specific T cells and PreS1 antibodies blocking HBV entry. Methods. Ten combinations of PreS1 and/or HDAg sequences were evaluated for induction of PreS1 antibodies and HBV- and HDV-specific T cells in vitro and in vivo. Neutralization of HBV by PreS1-specific murine and rabbit antibodies was evaluated in cell culture, and rabbit anti-PreS1 were tested for neutralization of HBV in mice repopulated with human hepatocytes. Results. The best vaccine candidate induced T cells to PreS1 and HDAg, and PreS1 antibodies blocking HBV entry in vitro. Importantly, adoptive transfer of PreS1 antibodies prevented, or modulated, HBV infection after a subsequent challenge in humanized mice. Conclusions. We here describe a novel immunotherapy for chronic HBV/HDV that targets viral entry to complement NAs and coming therapies inhibiting viral maturation

Nonnulla de taeniis, imprimis de bothriocephalo lato, ejusque expellendi methodo peculiari : dissertatio inauguralis pathologico-therapeutica / quam consensu et auctoritate amplissimi medicorum ordinis in Universitate Literarum Caesarea Dorpatensi, ut gradum medicinae doctoris rite adipiscatur, conscripsit et loco consueto publice defendet auctor Samuel P. Lieven, Livonus

http://tartu.ester.ee/record=b1920901~S1*es

Anterior Cruciate Ligament Repair Using Independent Suture Tape Reinforcement

Recently there has been renewed interest in primary repair of the anterior cruciate ligament (ACL). Repair of the acute proximal ruptured ACL can be achieved with the independent suture tape reinforcement ACL repair technique. The independent suture tape reinforcement technique reinforces the ligament as a secondary stabilizer, encouraging natural healing of the ligament by protecting it during the healing phase and supporting early mobilization. The purpose of this article is to describe, with video illustration, this ACL repair technique

Anterolateral Ligament Repair With Suture Tape Augmentation

Recent insights into the structure and function of the anterolateral ligament (ALL) of the knee has resulted in a recognition of its contribution in rotational control of the knee. Several ALL reconstruction techniques have been described in the literature. This article describes, with video illustration, a percutaneous repair technique using suture tape augmentation. A tendon graft is not needed. This technique allows early mobilization and encourages natural healing of the ligament by protecting the ligament during the healing phase as a secondary stabilizer