4,831 research outputs found
Effect of cell density on thrombin binding to a specific site on bovine vascular endothelial cells.
We studied thrombin binding to proliferating and confluent endothelial cells derived from bovine vascular endothelium. [125]thrombin was incubated with nonconfluent or confluent endothelial cells and both the total amount bound and the amount linked in a 77,000-dalton thrombin-cell complex were determined. Approximately 230,000 molecules of thrombin bound per cell in nonconfluent cultures compared to 12,800 molecules per cell in confluent cultures. Approximately 67,7000 thrombin molecules were bound in an apparently covalent complex, Mr = 77,000, with each cell in sparse cultures, whereas only 4,600 thrombin molecules per cell were bound in this complex with confluent cultures. Similar studies with [125I]thrombin and endothelial cells derived from bovine cornea revealed no difference either in the total amount of thrombin bound or in the amount bound in the 77,000-dalton complex using sparse or confluent cultures. When confluent vascular endothelial cultures were wounded, additional cellular binding sites for the 77,000-dalton complex with thrombin appeared within 24 h. A 237% increase in the amount of thrombin bound to these sites was induced by a wound which resulted in a 20% decrease in cell number in the monolayer. There was no significant increase in thrombin binding to other cellular sites at 24 h. These experiments provide evidence that the first change in thrombin binding after injury is an increase in the cellular sites involved in the 77,000-dalton complex, and suggest that thrombin binding to endothelial cells may be important in the vascular response to injury
Hybrid Atom--Photon Quantum Gate in a Superconducting Microwave Resonator
We propose a novel hybrid quantum gate between an atom and a microwave photon
in a superconducting coplanar waveguide cavity by exploiting the strong
resonant microwave coupling between adjacent Rydberg states. Using
experimentally achievable parameters gate fidelities are possible on
sub-s timescales for waveguide temperatures below 40 mK. This provides a
mechanism for generating entanglement between two disparate quantum systems and
represents an important step in the creation of a hybrid quantum interface
applicable for both quantum simulation and quantum information processing.Comment: 4 pages, 4 figure
Interplay of charge and spin correlations in nickel perovskites
Analyzing the motion of low--spin holes in a high--spin
background, we derive a sort of generalized t--J Hamiltonian for the planes of Sr--doped nickelates. In addition to the rather complex
carrier--spin and spin--spin couplings we take into account the coupling of the
doped holes to in--plane oxygen breathing modes by a Holstein--type interaction
term. Because of strong magnetic confinement effects the holes are nearly
entirely prelocalized and the electron--phonon coupling becomes much more
effective in forming polarons than in the isostructural cuprates. In the light
of recent experiments on we discuss how the variety of
the observed transport and charge/spin--ordering phenomena can be qualitatively
understood in terms of our model Hamiltonian.Comment: 2 pages, LTpaper.sty, Proc. XXI Int. Conf. on Low Temp. Phys. Prague
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Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface
We describe the design and characterization of superconducting coplanar
waveguide cavities tailored to facilitate strong coupling between
superconducting quantum circuits and single trapped Rydberg atoms. For initial
superconductor-atom experiments at 4.2 K, we show that resonator quality
factors above can be readily achieved. Furthermore, we demonstrate that
the incorporation of thick-film copper electrodes at a voltage antinode of the
resonator provides a route to enhance the zero-point electric fields of the
resonator in a trapping region that is 40 m above the chip surface,
thereby minimizing chip heating from scattered trap light. The combination of
high resonator quality factor and strong electric dipole coupling between the
resonator and the atom should make it possible to achieve the strong coupling
limit of cavity quantum electrodynamics with this system.Comment: 4 pages, 4 figure
Estimation of the geophysical properties of the ocean surface using aircraft microwave measurements
An improved model of the effects of sea state on microwave signature has been developed which incorporates the different effects of whitecaps and streaks to define the response of microwave channels to wind speed. This model has been demonstrated to agree with recent measurements. An approximation model has also been incorporated to describe the effects of precipitation on microwave radiation through a computationally rapid routine. The use of these models and a new technique to allow the selection of the most climatologically appropriate D-matrix is demonstrated in the inversion of data collected over the bering Sea. Surface wind speed agrees very well with observations while good results are obtained for integrated water vapor, and liquid water
Antiferromagnetic Domain Wall Engineering in Chromium Films
We have engineered an antiferromagnetic domain wall by utilizing a magnetic
frustration effect of a thin iron cap layer deposited on a chromium film.
Through lithography and wet etching we selectively remove areas of the Fe cap
layer to form a patterned ferromagnetic mask over the Cr film. Removing the Fe
locally removes magnetic frustration in user-defined regions of the Cr film. We
present x-ray microdiffraction microscopy results confirming the formation of a
90{\deg} spin-density wave propagation domain wall in Cr. This domain wall
nucleates at the boundary defined by our Fe mask.Comment: submitted to AP
Multi-stakeholder process of co-designing small-scale fisheries policy in South Africa.
In 2005, a group of researchers, community-based organizations and lawyers got together with small-scale fishers to launch a class action law suit against the government of South Africa in its allocation system of Individual Transferable Quotas, on the ground that the system was unfair to small-scale fishing communities and threatened their right to practise their livelihoods. This effort resulted in the cabinet adoption of a new small-scale fisheries policy in 2014, with amendments being made to fisheries law (the Marine Living Resource Act 18 of 1998) to accommodate the issues and concerns of small-scale fisheries. Draft regulations and an implementation plan have recently been released, paving the way for the implementation of small-scale fisheries allocations in 2016. These legal and policy shifts are of great significance for small-scale fisheries, both in South Africa and elsewhere, and deserve careful examination. This paper discusses the processes leading to the development of a new small-scale fisheries policy and what has followed since. Specifically, the analysis focuses on a variety of collaborations between scholars from different disciplines; researchers from multiple fields; community practitioners representing diverse professional and community perspectives; and community organizations across local, state, national and international levels. The paper uses a model of change that crosses research and practitioner boundaries based on three key strategies: getting noticed; organizing at scale; and getting a seat at the negotiation table. It also considers the “transdisciplinary” process of involving all relevant actors in strategic, collective, reflection–action–reflection–action “from below”, which was crucial in the co-designing of this small-scale policy formulation in South Africa
Resonant Inelastic X-Ray Scattering from Valence Excitations in Insulating Copper-Oxides
We report resonant inelastic x-ray measurements of insulating LaCuO
and SrCuOCl taken with the incident energy tuned near the Cu K
absorption edge. We show that the spectra are well described in a shakeup
picture in 3rd order perturbation theory which exhibits both incoming and
outgoing resonances, and demonstrate how to extract a spectral function from
the raw data. We conclude by showing {\bf q}-dependent measurements of the
charge transfer gap.Comment: minor notational changes, discussion of anderson impurity model
fixed, references added; accepted by PR
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