Microwave Susceptibility Observation of Interacting Many-Body Andreev States

Electrostatic charging affects the many-body spectrum of Andreev states, yet its influence on their microwave properties has not been elucidated. We developed a circuit quantum electrodynamics probe that, in addition to transition spectroscopy, measures the microwave susceptibility of different states of a semiconductor nanowire weak link with a single dominant (spin-degenerate) Andreev level. We found that the microwave susceptibility does not exhibit a particle-hole symmetry, which we qualitatively explain as an influence of Coulomb interaction. Moreover, our state-selective measurement reveals a large, π-phase shifted contribution to the response common to all many-body states which can be interpreted as arising from a phase-dependent continuum in the superconducting density of states.

Coherent manipulation of an Andreev spin qubit

Two promising architectures for solid-state quantum information processing are based on electron spins electrostatically confined in semiconductor quantum dots and the collective electrodynamic modes of superconducting circuits. Superconducting electrodynamic qubits involve macroscopic numbers of electrons and offer the advantage of larger coupling, whereas semiconductor spin qubits involve individual electrons trapped in microscopic volumes but are more difficult to link. We combined beneficial aspects of both platforms in the Andreev spin qubit: the spin degree of freedom of an electronic quasiparticle trapped in the supercurrent-carrying Andreev levels of a Josephson semiconductor nanowire. We performed coherent spin manipulation by combining single-shot circuit-quantum-electrodynamics readout and spin-flipping Raman transitions and found a spin-flip time T _S = 17 microseconds and a spin coherence time T _2E = 52 nanoseconds. These results herald a regime of supercurrent-mediated coherent spin-photon coupling at the single-quantum level.

Direct Microwave Measurement of Andreev-Bound-State Dynamics in a Semiconductor-Nanowire Josephson Junction

The modern understanding of the Josephson effect in mesosopic devices derives from the physics of Andreev bound states, fermionic modes that are localized in a superconducting weak link. Recently, Josephson junctions constructed using semiconducting nanowires have led to the realization of superconducting qubits with gate-tunable Josephson energies. We have used a microwave circuit QED architecture to detect Andreev bound states in such a gate-tunable junction based on an aluminum-proximitized indium arsenide nanowire. We demonstrate coherent manipulation of these bound states, and track the bound-state fermion parity in real time. Individual parity-switching events due to nonequilibrium quasiparticles are observed with a characteristic timescale T_{parity}=160±10  μs. The T_{parity} of a topological nanowire junction sets a lower bound on the bandwidth required for control of Majorana bound states.

Fusion of two novel genes, RBM15 and MKL1, in the t(1;22)(p13;q13) of acute megakaryoblastic leukemia

t(1;22) is the principal translocation of acute megakaryoblastic leukemias. Here we show this chromosomal rearrangement to result in the fusion of two novel genes, RNA-binding motif protein-15 (RBM15), an RNA recognition motif-encoding gene with homology to Drosophila spen, and Megakaryoblastic Leukemia-1 (MKL1), a gene encoding an SAP (SAF-A/B, Acinus and PIAS) DNA-binding domain.

Spontaneous blastomere fusion after freezing and thawing of early human embryos leads to polyploidy and chromosomal mosaicism

The incidence of blastomere fusion after cryopreservation of early human embryos (day 2 and day 3) was investigated using the standard propanediol technique. The process of fusion was observed in all developmental stages (from 2 to 10 cells) and the frequency of this event was 4.6% in day 2 (41/889) and 1.5% in day 3 (10/646) embryos that survived the thawing (embryos with 50-100% intact cells). Fusion of two, and occasionally of several, blastomeres resulted in the formation of multinucleated hybrid cells, which clearly indicated that the ploidy of these newly created cells had been altered. This event, depending on the number of fused cells per embryo, transformed the embryos into either entirely polyploid embryos (complete fusion at 2- or 3-cell stage) or into mosaics being a mixture of polyploid and normal cells. Chromosomal preparations of embryos affected by blastomere fusion indicated the presence of tetraploid mitotic plates. Also, fluorescence in-situ hybridization (FISH) analysis using DNA probes targeting unique sequences on chromosomes 9, 15, 17 and 22 indicated the existence of tetraploid and diploid fluorescence signals in the interphase nuclei within mosaics. Therefore, observations on live and fixed embryos suggested that tetraploid (4n) or hexaploid (6n) and tetraploid-diploid or more complex aberrations of ploidy might be formed as a consequence of blastomere fusion. Furthermore, this demonstrates that freezing and thawing may induce numerical chromosomal changes in human embryos.

Clonal heterogeneity of dendritic cells derived from patients with chronic myeloid leukemia and enhancement of their T-cells stimulatory activity by IFN-alpha

Adoptive immunotherapy in form of donor leukocyte infusions is effective in a significant number of patients with chronic myeloid leukemia (CML) that have relapsed after allogeneic bone marrow transplantation (BMT). However, the therapy is associated with clinically significant side effects such as graft-versus-host disease (GVHD) and bone marrow (BM) hypoplasia that may be avoided through the administration of T cells with specific antileukemic activity. Dendritic cells (DC) functioning as potent antigen presenting cells (APC) may play an important role in the generation of T cells with specificity against CML. We examined a subpopulation of CD1a+/CD14- DC generated in vitro from BM of normal subjects and patients with CML using granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4). These DC derived from both the BM of normal subjects and of patients with CML, differentiated and matured in culture in a similar way. However, DC derived from patients with CML, displayed decreased activity when tested with allogeneic T cells in a mixed lymphocyte reaction (MLR). Addition of interferon-alpha (IFN-alpha) to DC cultures significantly upregulated the expression of major histocompatibility complex (MHC) molecules (class I and class II) and costimulatory molecules (B7.1 and B7.2) on DC from normal donors and CML patients. However, DC grown from CML patients required a higher concentration of IFN-alpha. IFN-alpha also significantly improved the capacity of CML DC to stimulate T-lymphocyte responses. Fluorescence in situ hybridization (FISH) showed that only some CD1a+/CD14- DC derived from BM of patients with CML expressed the bcr/abl fusion gene. Incubation with INF-alpha decreased the proportion of bcr/abl positive DC.

Frequent monoallelic loss of D13S319 in multiple myeloma patients shown by interphase fluorescence in situ hybridization

Deletions or monosomy of chromosome 13 are frequent in multiple myeloma (MM). A candidate tumor suppressor gene might reside telomeric of the retinoblastoma gene (RBl) at band 13q14 and to play a role in B cell neoplasm. The D13S319 locus, between RB1 and D13S25 loci at 13q14 is the most commonly deleted marker in chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL). We evaluated the D13S319 locus in 24 MM cases by fluorescence in situ hybridization (FISH). We observed monosomy for D13S319 in 6/20 (30%) MM patients with an apparently normal karyotype. As expected, in four karyotypically abnormal MM cases with partial or complete monosomy for chromosome 13, all of them had monoallelic loss of D13S319. Our results indicated that the loss of D13S319 is commonly found in MM, even at diagnosis, and is more frequent than predicted based on conventional cytogenetic analysis of metaphase spreads. This finding implicates a candidate tumor suppressor gene at 13q14 in the pathogenesis of MM.

Pictorial superiority during verbal learning tasks in moderate to severe closed head injury: additional evidence

Evidence for picture superiority in verbal learning following moderate to severe closed head injury (CHI) was found in a study involving 31 participants with CHI and 31 noninjured participants. A multitrial free-recall paradigm was implemented incorporating three modalities: Auditory, visual, and simultaneous auditory plus visual. Participants with moderate to severe CHI learned fewer words and at a slower rate than the noninjured participants. The visual presentation of objects (with or without the simultaneous auditory presentation of names) resulted in better learning than the auditory presentation alone.