169 research outputs found
Wideband and on-chip excitation for dynamical spin injection into graphene
Graphene is an ideal material for spin transport as very long spin relaxation
times and lengths can be achieved even at room temperature. However, electrical
spin injection is challenging due to the conductivity mismatch problem. Spin
pumping driven by ferromagnetic resonance is a neat way to circumvent this
problem as it produces a pure spin current in the absence of a charge current.
Here, we show spin pumping into single layer graphene in micron scale devices.
A broadband on-chip RF current line is used to bring micron scale permalloy
(NiFe) pads to ferromagnetic resonance with a magnetic field
tunable resonance condition. At resonance, a spin current is emitted into
graphene, which is detected by the inverse spin hall voltage in a close-by
platinum electrode. Clear spin current signals are detected down to a power of
a few milliwatts over a frequency range of 2 GHz to 8 GHz. This compact device
scheme paves the way for more complex device structures and allows the
investigation of novel materials.Comment: 7 pages, 4 figure
Improved limits on nuebar emission from mu+ decay
We investigated mu+ decays at rest produced at the ISIS beam stop target.
Lepton flavor (LF) conservation has been tested by searching for \nueb via the
detection reaction p(\nueb,e+)n. No \nueb signal from LF violating mu+ decays
was identified. We extract upper limits of the branching ratio for the LF
violating decay mu+ -> e+ \nueb \nu compared to the Standard Model (SM) mu+ ->
e+ nue numub decay: BR < 0.9(1.7)x10^{-3} (90%CL) depending on the spectral
distribution of \nueb characterized by the Michel parameter rho=0.75 (0.0).
These results improve earlier limits by one order of magnitude and restrict
extensions of the SM in which \nueb emission from mu+ decay is allowed with
considerable strength. The decay \mupdeb as source for the \nueb signal
observed in the LSND experiment can be excluded.Comment: 10 pages, including 1 figure, 1 tabl
Multipartite Entanglement in Rabi Driven Superconducting Qubits
Exploring highly connected networks of qubits is invaluable for implementing
various quantum algorithms and simulations as it allows for entangling qubits
with reduced circuit depth. Here, we demonstrate a multi-qubit STAR (Sideband
Tone Assisted Rabi driven) gate. Our scheme is inspired by the ion qubit
M{\o}lmer-S{\o}rensen gate and is mediated by a shared photonic mode and
Rabi-driven superconducting qubits, which relaxes restrictions on qubit
frequencies during fabrication and supports scalability. We achieve a two-qubit
gate with maximum state fidelity of 0.95 in 310 ns, a three-qubit gate with
state fidelity 0.905 in 217 ns, and a four-qubit gate with state fidelity 0.66
in 200 ns. Furthermore, we develop a model of the gate that show the four-qubit
gate is limited by shared resonator losses and the spread of qubit-resonator
couplings, which must be addressed to reach high-fidelity operations.Comment: 16 pages, 14 figure
Modularity and hormone sensitivity of the Drosophila melanogaster insulin receptor/target of rapamycin interaction proteome
First systematic analysis of the evolutionary conserved InR/TOR pathway interaction proteome in Drosophila.Quantitative mass spectrometry revealed that 22% of identified protein interactions are regulated by the growth hormone insulin affecting membrane proximal as well as intracellular signaling complexes.Systematic RNA interference linked a significant fraction of network components to the control of dTOR kinase activity.Combined biochemical and genetic data suggest dTTT, a dTOR-containing complex required for cell growth control by dTORC1 and dTORC2 in vivo
Spin glasses and algorithm benchmarks: A one-dimensional view
Spin glasses are paradigmatic models that deliver concepts relevant for a
variety of systems. However, rigorous analytical results are difficult to
obtain for spin-glass models, in particular for realistic short-range models.
Therefore large-scale numerical simulations are the tool of choice. Concepts
and algorithms derived from the study of spin glasses have been applied to
diverse fields in computer science and physics. In this work a one-dimensional
long-range spin-glass model with power-law interactions is discussed. The model
has the advantage over conventional systems in that by tuning the power-law
exponent of the interactions the effective space dimension can be changed thus
effectively allowing the study of large high-dimensional spin-glass systems to
address questions as diverse as the existence of an Almeida-Thouless line,
ultrametricity and chaos in short range spin glasses. Furthermore, because the
range of interactions can be changed, the model is a formidable test-bed for
optimization algorithms.Comment: 10 pages, 8 figures (two in crappy quality due to archive
restrictions). Proceedings of the International Workshop on
Statistical-Mechanical Informatics 2007, Kyoto (Japan) September 16-19, 200
Guidelines for Clinical Studies with Compression Devices in Patients with Venous Disorders of the Lower Limb
Digitalitzat per Artypla
The Drosophila FoxA Ortholog Fork Head Regulates Growth and Gene Expression Downstream of Target of Rapamycin
Forkhead transcription factors of the FoxO subfamily regulate gene expression programs downstream of the insulin signaling network. It is less clear which proteins mediate transcriptional control exerted by Target of rapamycin (TOR) signaling, but recent studies in nematodes suggest a role for FoxA transcription factors downstream of TOR. In this study we present evidence that outlines a similar connection in Drosophila, in which the FoxA protein Fork head (FKH) regulates cellular and organismal size downstream of TOR. We find that ectopic expression and targeted knockdown of FKH in larval tissues elicits different size phenotypes depending on nutrient state and TOR signaling levels. FKH overexpression has a negative effect on growth under fed conditions, and this phenotype is not further exacerbated by inhibition of TOR via rapamycin feeding. Under conditions of starvation or low TOR signaling levels, knockdown of FKH attenuates the size reduction associated with these conditions. Subcellular localization of endogenous FKH protein is shifted from predominantly cytoplasmic on a high-protein diet to a pronounced nuclear accumulation in animals with reduced levels of TOR or fed with rapamycin. Two putative FKH target genes, CG6770 and cabut, are transcriptionally induced by rapamycin or FKH expression, and silenced by FKH knockdown. Induction of both target genes in heterozygous TOR mutant animals is suppressed by mutations in fkh. Furthermore, TOR signaling levels and FKH impact on transcription of the dFOXO target gene d4E-BP, implying a point of crosstalk with the insulin pathway. In summary, our observations show that an alteration of FKH levels has an effect on cellular and organismal size, and that FKH function is required for the growth inhibition and target gene induction caused by low TOR signaling levels
Prevalence and overlap of different lipid abnormalities in statin-treated patients at high cardiovascular risk in clinical practice in Germany
Construction of a large scale integrated map of macrophage pathogen recognition and effector systems
<p>Abstract</p> <p>Background</p> <p>In an effort to better understand the molecular networks that underpin macrophage activation we have been assembling a map of relevant pathways. Manual curation of the published literature was carried out in order to define the components of these pathways and the interactions between them. This information has been assembled into a large integrated directional network and represented graphically using the modified Edinburgh Pathway Notation (mEPN) scheme.</p> <p>Results</p> <p>The diagram includes detailed views of the toll-like receptor (TLR) pathways, other pathogen recognition systems, NF-kappa-B, apoptosis, interferon signalling, MAP-kinase cascades, MHC antigen presentation and proteasome assembly, as well as selected views of the transcriptional networks they regulate. The integrated pathway includes a total of 496 unique proteins, the complexes formed between them and the processes in which they are involved. This produces a network of 2,170 nodes connected by 2,553 edges.</p> <p>Conclusions</p> <p>The pathway diagram is a navigable visual aid for displaying a consensus view of the pathway information available for these systems. It is also a valuable resource for computational modelling and aid in the interpretation of functional genomics data. We envisage that this work will be of value to those interested in macrophage biology and also contribute to the ongoing Systems Biology community effort to develop a standard notation scheme for the graphical representation of biological pathways.</p
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