497 research outputs found
SGPN: Similarity Group Proposal Network for 3D Point Cloud Instance Segmentation
We introduce Similarity Group Proposal Network (SGPN), a simple and intuitive
deep learning framework for 3D object instance segmentation on point clouds.
SGPN uses a single network to predict point grouping proposals and a
corresponding semantic class for each proposal, from which we can directly
extract instance segmentation results. Important to the effectiveness of SGPN
is its novel representation of 3D instance segmentation results in the form of
a similarity matrix that indicates the similarity between each pair of points
in embedded feature space, thus producing an accurate grouping proposal for
each point. To the best of our knowledge, SGPN is the first framework to learn
3D instance-aware semantic segmentation on point clouds. Experimental results
on various 3D scenes show the effectiveness of our method on 3D instance
segmentation, and we also evaluate the capability of SGPN to improve 3D object
detection and semantic segmentation results. We also demonstrate its
flexibility by seamlessly incorporating 2D CNN features into the framework to
boost performance
Improved Arene Fluorination Methodology for I(III) Salts
The use of low polarity aromatic solvents (benzene or toluene) and/or the removal of inorganic salts results in dramatically improved yields of fluorinated arenes from diaryliodonium salts. This methodology is shown to “scale down” to the conditions used typically for radiotracer synthesis
ROTATIONAL-DYNAMICS OF SOLID C-70 - A NEUTRON-SCATTERING STUDY
PMID: 10011126PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.PMID: 10011126 This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K.We report the results of neutron-diffraction and low-energy neutron-inelastic-scattering experiments on high-purity solid C-70 between 10 and 640 K. Thermal hysteresis effects are found to accompany structural changes both on cooling and on heating. The observed diffuse scattering intensity does not change with temperature. At 10 K broad librational peaks are observed at 1.82(16) meV [full width at half maximum=1.8(5) meV]. The peaks soften and broaden further with increasing temperature. At and above room temperature, they collapse into a single quasielastic line. At 300 K, the diffusive reorientational motion appears to be somewhat anisotropic, becoming less so with increasing temperature. An isotropic rotational diffusion model, in which the motions of adjacent molecules are uncorrelated, describes well the results at 525 K. The temperature dependence of the rotational diffusion constants is consistent with a thermally activated process having an activation energy of 32(7) meV.This work at the University of Sussex at supported by the Science and Engineering Research Council, U.K
Allele quantification using molecular inversion probes (MIP)
Detection of genomic copy number changes has been an important research area, especially in cancer. Several high-throughput technologies have been developed to detect these changes. Features that are important for the utility of technologies assessing copy number changes include the ability to interrogate regions of interest at the desired density as well as the ability to differentiate the two homologs. In addition, assessing formaldehyde fixed and paraffin embedded (FFPE) samples allows the utilization of the vast majority of cancer samples. To address these points we demonstrate the use of molecular inversion probe (MIP) technology to the study of copy number. MIP is a high-throughput genotyping technology capable of interrogating >20 000 single nucleotide polymorphisms in the same tube. We have shown the ability of MIP at this multiplex level to provide copy number measurements while obtaining the allele information. In addition we have demonstrated a proof of principle for copy number analysis in FFPE samples
Demonstration of entanglement-by-measurement of solid state qubits
Projective measurements are a powerful tool for manipulating quantum states.
In particular, a set of qubits can be entangled by measurement of a joint
property such as qubit parity. These joint measurements do not require a direct
interaction between qubits and therefore provide a unique resource for quantum
information processing with well-isolated qubits. Numerous schemes for
entanglement-by-measurement of solid-state qubits have been proposed, but the
demanding experimental requirements have so far hindered implementations. Here
we realize a two-qubit parity measurement on nuclear spins in diamond by
exploiting the electron spin of a nitrogen-vacancy center as readout ancilla.
The measurement enables us to project the initially uncorrelated nuclear spins
into maximally entangled states. By combining this entanglement with
high-fidelity single-shot readout we demonstrate the first violation of Bells
inequality with solid-state spins. These results open the door to a new class
of experiments in which projective measurements are used to create, protect and
manipulate entanglement between solid-state qubits.Comment: 6 pages, 4 figure
Absence of lattice strain anomalies at the electronic topological transition in zinc at high pressure
High pressure structural distortions of the hexagonal close packed (hcp)
element zinc have been a subject of controversy. Earlier experimental results
and theory showed a large anomaly in lattice strain with compression in zinc at
about 10 GPa which was explained theoretically by a change in Fermi surface
topology. Later hydrostatic experiments showed no such anomaly, resulting in a
discrepancy between theory and experiment. We have computed the compression and
lattice strain of hcp zinc over a wide range of compressions using the
linearized augmented plane wave (LAPW) method paying special attention to
k-point convergence. We find that the behavior of the lattice strain is
strongly dependent on k-point sampling, and with large k-point sets the
previously computed anomaly in lattice parameters under compression disappears,
in agreement with recent experiments.Comment: 9 pages, 6 figures, Phys. Rev. B (in press
Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond
We investigate spin-dependent decay and intersystem crossing in the optical
cycle of single negatively-charged nitrogen-vacancy (NV) centres in diamond. We
use spin control and pulsed optical excitation to extract both the
spin-resolved lifetimes of the excited states and the degree of
optically-induced spin polarization. By optically exciting the centre with a
series of picosecond pulses, we determine the spin-flip probabilities per
optical cycle, as well as the spin-dependent probability for intersystem
crossing. This information, together with the indepedently measured decay rate
of singlet population provides a full description of spin dynamics in the
optical cycle of NV centres. The temperature dependence of the singlet
population decay rate provides information on the number of singlet states
involved in the optical cycle.Comment: 11 pages, 5 figure
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Implementing evidence-based interventions in health care: application of the replicating effective programs framework
Background: We describe the use of a conceptual framework and implementation protocol to prepare effective health services interventions for implementation in community-based (i.e., non-academic-affiliated) settings. Methods: The framework is based on the experiences of the U.S. Centers for Disease Control and Prevention (CDC) Replicating Effective Programs (REP) project, which has been at the forefront of developing systematic and effective strategies to prepare HIV interventions for dissemination. This article describes the REP framework, and how it can be applied to implement clinical and health services interventions in community-based organizations. Results: REP consists of four phases: pre-conditions (e.g., identifying need, target population, and suitable intervention), pre-implementation (e.g., intervention packaging and community input), implementation (e.g., package dissemination, training, technical assistance, and evaluation), and maintenance and evolution (e.g., preparing the intervention for sustainability). Key components of REP, including intervention packaging, training, technical assistance, and fidelity assessment are crucial to the implementation of effective interventions in health care. Conclusion: REP is a well-suited framework for implementing health care interventions, as it specifies steps needed to maximize fidelity while allowing opportunities for flexibility (i.e., local customizing) to maximize transferability. Strategies that foster the sustainability of REP as a tool to implement effective health care interventions need to be developed and tested
The Risks of Key Recovery, Key Escrow, and Trusted Third-Party Encryption
A variety of "key recovery," "key escrow," and "trusted third-party" encryption requirements have been suggested in recent years by government agencies seeking to conduct covert surveillance within the changing environments brought about by new technologies. This report examines the fundamental properties of these requirements and attempts to outline the technical risks, costs, and implications of deploying systems that provide government access to encryption keys
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