Efficient quantum computing using coherent photon conversion

Single photons provide excellent quantum information carriers, but current schemes for preparing, processing and measuring them are inefficient. For example, down-conversion provides heralded, but randomly timed single photons, while linear-optics gates are inherently probabilistic. Here, we introduce a deterministic scheme for photonic quantum information. Our single, versatile process---coherent photon conversion---provides a full suite of photonic quantum processing tools, from creating high-quality heralded single- and multiphoton states free of higher-order imperfections to implementing deterministic multiqubit entanglement gates and high-efficiency detection. It fulfils all requirements for a scalable photonic quantum computing architecture. Using photonic crystal fibres, we experimentally demonstrate a four-colour nonlinear process usable for coherent photon conversion and show that current technology provides a feasible path towards deterministic operation. Our scheme, based on interacting bosonic fields, is not restricted to optical systems, but could also be implemented in optomechanical, electromechanical and superconducting systems which exhibit extremely strong intrinsic nonlinearities.Comment: 12 pages, 9 figure

The association of serum calprotectin (S100A8/S100A9) levels with disease relapses in PR3-ANCA-associated vasculitis

OBJECTIVES: S100A8/A9 (calprotectin) has shown promise as a biomarker for predicting relapse in AAV. This study investigated serum S100A8/A9 levels as a biomarker predicting future relapse in a large cohort of patients with severe ANCA-associated vasculitis (AAV). METHODS: Serum levels of S100A8/A9 were measured at baseline, months 2, and 6 following treatment initiation in 144 patients in the RAVE trial (cyclophosphamide/azathioprine vs. rituximab for induction of remission) who attained complete remission. RESULTS: Patients were divided into 4 groups: PR3-ANCA with (n=37), and without (n=56) relapse, and MPO-ANCA with (n=6) and without (n=45) relapse. Serum S100A8/A9 levels decreased in all groups during the first 6 months of treatment. The percentage reduction from baseline to month 2 was significantly different between relapsers and non-relapsers in the PR3-AAV group (p=0.046). A significantly higher risk of relapse was associated with an increase in S100A8/A9 between baseline and month 2 (p=0.006) and baseline and month 6 (p=0.0099) for all patients. Subgroup analysis demonstrated it was patients treated with rituximab and who increased levels of S100A8/A9 who were at greatest risk of future relapse (p=0.028). CONCLUSION: An increase in serum S100A8/A9 by month 2 or 6 compared to baseline identifies a subgroup of PR3-ANCA patients treated with rituximab at higher risk of relapse by 18 months. As rituximab is increasingly used for remission induction in relapsing PR3-ANCA patients, S100A8/A9 may assist in identifying those patients requiring more intensive or prolonged treatment

Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices

By stacking various two-dimensional (2D) atomic crystals [1] on top of each other, it is possible to create multilayer heterostructures and devices with designed electronic properties [2-5]. However, various adsorbates become trapped between layers during their assembly, and this not only affects the resulting quality but also prevents the formation of a true artificial layered crystal upheld by van der Waals interaction, creating instead a laminate glued together by contamination. Transmission electron microscopy (TEM) has shown that graphene and boron nitride monolayers, the two best characterized 2D crystals, are densely covered with hydrocarbons (even after thermal annealing in high vacuum) and exhibit only small clean patches suitable for atomic resolution imaging [6-10]. This observation seems detrimental for any realistic prospect of creating van der Waals materials and heterostructures with atomically sharp interfaces. Here we employ cross sectional TEM to take a side view of several graphene-boron nitride heterostructures. We find that the trapped hydrocarbons segregate into isolated pockets, leaving the interfaces atomically clean. Moreover, we observe a clear correlation between interface roughness and the electronic quality of encapsulated graphene. This work proves the concept of heterostructures assembled with atomic layer precision and provides their first TEM images

Prolonged Depression-Like Behavior Caused by Immune Challenge: Influence of Mouse Strain and Social Environment

Immune challenge by bacterial lipopolysaccharide (LPS) causes short-term behavioral changes indicative of depression. The present study sought to explore whether LPS is able to induce long-term changes in depression-related behavior and whether such an effect depends on mouse strain and social context. LPS (0.83 mg/kg) or vehicle was administered intraperitoneally to female CD1 and C57BL/6 mice that were housed singly or in groups of 4. Depression-like behavior was assessed with the forced swim test (FST) 1 and 28 days post-treatment. Group-housed CD1 mice exhibited depression-like behavior 1 day post-LPS, an effect that leveled off during the subsequent 28 days, while the behavior of singly housed CD1 mice was little affected. In contrast, singly housed C57BL/6 mice responded to LPS with an increase in depression-like behavior that was maintained for 4 weeks post-treatment and confirmed by the sucrose preference test. Group-housed C57BL/6 mice likewise displayed an increased depression-like behavior 4 weeks post-treatment. The behavioral changes induced by LPS in C57BL/6 mice were associated with a particularly pronounced rise of interleukin-6 in blood plasma within 1 day post-treatment and with changes in the dynamics of the corticosterone response to the FST. The current data demonstrate that immune challenge with LPS is able to induce prolonged depression-like behavior, an effect that depends on genetic background (strain). The discovery of an experimental model of long-term depression-like behavior after acute immune challenge is of relevance to the analysis of the epigenetic and pathophysiologic mechanisms of immune system-related affective disorders

A CD8+ T cell transcription signature predicts prognosis in autoimmune disease.

Autoimmune diseases are common and debilitating, but their severe manifestations could be reduced if biomarkers were available to allow individual tailoring of potentially toxic immunosuppressive therapy. Gene expression-based biomarkers facilitating such tailoring of chemotherapy in cancer, but not autoimmunity, have been identified and translated into clinical practice. We show that transcriptional profiling of purified CD8(+) T cells, which avoids the confounding influences of unseparated cells, identifies two distinct subject subgroups predicting long-term prognosis in two autoimmune diseases, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a chronic, severe disease characterized by inflammation of medium-sized and small blood vessels, and systemic lupus erythematosus (SLE), characterized by autoantibodies, immune complex deposition and diverse clinical manifestations ranging from glomerulonephritis to neurological dysfunction. We show that the subset of genes defining the poor prognostic group is enriched for genes involved in the interleukin-7 receptor (IL-7R) pathway and T cell receptor (TCR) signaling and those expressed by memory T cells. Furthermore, the poor prognostic group is associated with an expanded CD8(+) T cell memory population. These subgroups, which are also found in the normal population and can be identified by measuring expression of only three genes, raise the prospect of individualized therapy and suggest new potential therapeutic targets in autoimmunity

Female gamers’ experience of online harassment and social support in online gaming: a qualitative study

Female gaming is a relatively under-researched area, and female gamers often report experiencing harassment whilst playing online. The present study explored female experiences of social support while playing online video games, because of the previous research suggesting that females often experience harassment and negative interactions during game play. Data were collected from an online discussion forum, and comprised posts drawn from 271 female gamers. Thematic analysis of the discussions suggested that a lack of social support and harassment frequently led to female gamers playing alone, playing anonymously, and moving groups regularly. The female gamers reported experiencing anxiety and loneliness due to this lack of social support, and for many, this was mirrored in their experiences of social support outside of gaming. The female gamers frequently accepted the incorporation into their gaming of specific coping strategies to mitigate online harassment, including actively hiding their identity and avoiding all forms of verbal communication with other players. These themes are discussed in relation to relevant research in the area, along with recommendations for future research and consideration of possible explanations for the themes observed