Unconventional superconductivity in CuxBi2Se3

We report point contact measurements in high quality single crystals of Cu0.2Bi2Se3. We observe three different kinds of spectra: (1) Andreev-reflection spectra, from which we infer a superconducting gap size of 0.6mV; (2) spectra with a large gap which closes above Tc at about 10K; and (3) tunneling-like spectra with zero-bias conductance peaks. These tunneling spectra show a very large gap of ~2meV (2Delta/KTc ~ 14)

Proximity induced superconductivity by Bi in topological Bi2Te2SeBi_2Te_2Se and Bi2Se3Bi_2Se_3 films: Evidence for a robust zero energy bound state possibly due to Majorana Fermions

Point contact conductance measurements on topological $Bi_2Te_2Se$ and $Bi_2Se_3$ films reveal a signature of superconductivity below 2-3 K. In particular, critical current dips and a robust zero bias conductance peak are observed. The latter suggests the presence of zero energy bound states which could be assigned to Majorana Fermions in an unconventional topological superconductor. We attribute these novel observations to proximity induced local superconductivity in the films by small amounts of superconducting Bi inclusions or segregation to the surface, and provide supportive evidence for these effects.Comment: Accepted for publication in Physical Review B (Dec. 20, 2011), 15 figures. Version V1: arXiv:1111.3445v1 [cond-mat.supr-con] 15 Nov 201

Probing the surface states in Bi2Se3 using the Shubnikov-de Haas effect

Shubnikov-de Haas (SdH) oscillations are observed in Bi2Se3 flakes with high carrier concentration and low bulk mobility. These oscillations probe the protected surface states and enable us to extract their carrier concentration, effective mass and Dingle temperature. The Fermi momentum obtained is in agreement with angle resolved photoemission spectroscopy (ARPES) measurements performed on crystals from the same batch. We study the behavior of the Berry phase as a function of magnetic field. The standard theoretical considerations fail to explain the observed behavior.Comment: 6 pages, 8 figures. Accepted to Physical Review

Mouse Plasmacytoid Cells: Long-lived Cells, Heterogeneous in Surface Phenotype and Function, that Differentiate Into CD8+ Dendritic Cells Only after Microbial Stimulus

The CD45RAhiCD11cint plasmacytoid predendritic cells (p-preDCs) of mouse lymphoid organs, when stimulated in culture with CpG or influenza virus, produce large amounts of type I interferons and transform without division into CD8+CD205− DCs. P-preDCs express CIRE, the murine equivalent of DC-specific intercellular adhesion molecule 3 grabbing nonintegrin (DC-SIGN). P-preDCs are divisible by CD4 expression into two subgroups differing in turnover rate and in response to Staphylococcus aureus. The kinetics of bromodeoxyuridine labeling and the results of transfer to normal recipient mice indicate that CD4− p-preDCs are the immediate precursors of CD4+ p-preDCs. Similar experiments indicate that p-preDCs are normally long lived and are not the precursors of the short-lived steady-state conventional DCs. However, in line with the culture studies on transfer to influenza virus-stimulated mice the p-preDCs transform into CD8+CD205− DCs, distinct from conventional CD8+CD205+ DCs. Hence as well as activating preexistant DCs, microbial infection induces a wave of production of a new DC subtype. The functional implications of this shift in the DC network remain to be determined

Oligodendrocyte-myelin glycoprotein is present in lipid rafts and caveolin-1-enriched membranes

The oligodendrocyte-myelin glycoprotein is a ligand of the neuronal Nogo receptor and a potent inhibitor of neurite outgrowth, but its physiological function remains to be elucidated. The oligodendrocyte-myelin glycoprotein is anchored solely in the outer leaflet of the plasma membrane via its glycosylphosphatidylinositol anchor, and through its leucine-rich repeat domain, it likely interacts with other proteins. In the present study, we compare its buoyancy and detergent solubility characteristics with those of other myelin proteins. Based on its detergent solubility profile and membrane fractionation using established ultracentrifugation procedures, we conclude that the oligodendrocyte-myelin glycoprotein is a lipid raft component that is closely associated with the axolemma. Moreover, it associates with caveolin-1 and caveolin-1-enriched membranes. We postulate that, by virtue of its concentration in lipid rafts and perhaps through interactions with caveolin-1, the oligodendrocyte-myelin glycoprotein may influence signaling pathways. © 2005 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48768/1/20237_ftp.pd

Safety Assessment for Explosive Risk (SAFER) peer review report.

At the direction of the Department of Defense Explosives Safety Board (DDESB), a Peer Review Team was established to review the status of development of the risk-based explosives safety siting process and criteria as currently implemented in the software 'Safety Assessment for Explosive Risk (SAFER)' Version 2.1. The objective of the Peer Review Team was to provide an independent evaluation of the components of the SAFER model, the ongoing development of the model and the risk assessment process and criteria. This peer review report addressed procedures; protocols; physical and statistical science algorithms; related documents; and software quality assurance, validation and verification. Overall, the risk-based method in SAFER represents a major improvement in the Department of Defense (DoD) approach to explosives safety management. The DDESB and Risk Based Explosives Safety Criteria Team (RBESCT) have made major strides in developing a methodology, which over time may become a worldwide model. The current status of all key areas of the SAFER code has been logically developed and is defensible. Continued improvement and refinement can be expected as implementation proceeds. A consistent approach to addressing and refining uncertainty in each of the primary areas (probability of event, consequences of event and exposure) will be a very beneficial future activity

Human CLEC9A antibodies deliver Wilms' tumor 1 (WT1) antigen to CD141+ dendritic cells to activate naïve and memory WT1‐specific CD8+ T cells

Objectives Vaccines that prime Wilms' tumor 1 (WT1)‐specific CD8+ T cells are attractive cancer immunotherapies. However, immunogenicity and clinical response rates may be enhanced by delivering WT1 to CD141+ dendritic cells (DCs). The C‐type lectin‐like receptor CLEC9A is expressed exclusively by CD141+ DCs and regulates CD8+ T‐cell responses. We developed a new vaccine comprising a human anti‐CLEC9A antibody fused to WT1 and investigated its capacity to target human CD141+ DCs and activate naïve and memory WT1‐specific CD8+ T cells. Methods WT1 was genetically fused to antibodies specific for human CLEC9A, DEC‐205 or β‐galactosidase (untargeted control). Activation of WT1‐specific CD8+ T‐cell lines following cross‐presentation by CD141+ DCs was quantified by IFNγ ELISPOT. Humanised mice reconstituted with human immune cell subsets, including a repertoire of naïve WT1‐specific CD8+ T cells, were used to investigate naïve WT1‐specific CD8+ T‐cell priming. Results The CLEC9A‐WT1 vaccine promoted cross‐presentation of WT1 epitopes to CD8+ T cells and mediated priming of naïve CD8+ T cells more effectively than the DEC‐205‐WT1 and untargeted control‐WT1 vaccines. Conclusions Delivery of WT1 to CD141+ DCs via CLEC9A stimulates CD8+ T cells more potently than either untargeted delivery or widespread delivery to all Ag‐presenting cells via DEC‐205, suggesting that cross‐presentation by CD141+ DCs is sufficient for effective CD8+ T‐cell priming in humans. The CLEC9A‐WT1 vaccine is a promising candidate immunotherapy for malignancies that express WT1