3,197 research outputs found
Compact multi-aperture imaging with high-angular-resolution
Previous reports have demonstrated that it is possible to emulate the imaging function of a single conventional
lens with an NxN array of identical lenslets to provide an N-fold reduction in imaging-system track length. This
approach limits the application to low-resolution imaging. We highlight how using an array of dissimilar lenslets,
with an array width that can be much wider than the detector array, high-resolution super-resolved imaging is
possible. We illustrate this approach with a ray-traced design and optimization of a long-wave infrared system
employing a 3x3 array of free-form lenslets to provide a four-fold reduction in track length compared to a baseline
system. Simulations of image recovery show that recovered image quality is comparable to that of the baseline
system
Multi-aperture foveated imaging
Foveated imaging, such as that evolved by biological systems to provide high angular resolution with a reduced space–bandwidth product, also offers advantages for man-made task-specific imaging. Foveated imaging systems using exclusively optical distortion are complex, bulky, and high cost, however. We demonstrate foveated imaging using a planar array of identical cameras combined with a prism array and superresolution reconstruction of a mosaicked image with a foveal variation in angular resolution of 5.9:1 and a quadrupling of the field of view. The combination of low-cost, mass-produced cameras and optics with computational image recovery offers enhanced capability of achieving large foveal ratios from compact, low-cost imaging systems
Synthetic Applications and Methodological Developments of Donor-Acceptor Cyclopropanes and Related Compounds
Donor-acceptor cyclopropanes are convenient precursors to reactive and versatile 1,3-dipoles, and have found application in the synthesis of a variety of carbo- and heterocyclic scaffolds. This perspective review details our laboratory’s use of donor-acceptor cyclopropanes as intermediates toward the total synthesis of various natural products. We also discuss our work in the development of novel cycloadditions and rearrangements of donor-acceptor cyclopropanes and aziridines, as well as an example of an aryne insertion proceeding via fragmentation of a transient donor-acceptor cyclobutane
Reparametrising the Skyrme Model using the Lithium-6 Nucleus
The minimal energy B=6 solution of the Skyrme model is a static soliton with
symmetry. The symmetries of the solution imply that the quantum
numbers of the ground state are the same as those of the Lithium-6 nucleus.
This identification is considered further by obtaining expressions for the mean
charge radius and quadrupole moment, dependent only on the Skyrme model
parameters (a dimensionless constant) and (the pion decay
constant). The optimal values of these parameters have often been deliberated
upon, and we propose, for , changing them from those which are most
commonly accepted. We obtain specific values for these parameters for B=6, by
matching with properties of the Lithium-6 nucleus. We find further support for
the new values by reconsidering the -particle and deuteron as quantized
B=4 and B=2 Skyrmions.Comment: 18 page
Two Foraging Algorithms for Robot Swarms Using Only Local Communication
Large collections of robots have the potential to perform tasks collectively using distributed control algorithms. These algorithms require communication between robots to allow the robots to coordinate their behavior and act as a collective. In this paper we describe two algorithms which allow coordination between robots, but do not require physical environment marks such as pheromones. Instead, these algorithms rely on simple, local, low bandwidth, direct communication between robots. We describe the algorithms and measure their performance in worlds with and without obstacles.Engineering and Applied Science
Utility of the new Movement Disorder Society clinical diagnostic criteria for Parkinson's disease applied retrospectively in a large cohort study of recent onset cases
Objective:
To examine the utility of the new Movement Disorder Society (MDS) diagnostic criteria in a large cohort of Parkinson's disease (PD) patients.
Methods:
Recently diagnosed (<3.5 years) PD cases fulfilling United Kingdom (UK) brain bank criteria in Tracking Parkinson's, a UK multicenter prospective natural history study were assessed by retrospective application of the MDS criteria.
Results:
In 2000 cases, 1835 (91.7%) met MDS criteria for PD, either clinically established (n = 1261, 63.1%) or clinically probable (n = 574, 28.7%), leaving 165 (8.3%) not fulfilling criteria. Clinically established cases were significantly more likely to have limb rest tremor (89.3%), a good l-dopa response (79.5%), and olfactory loss (71.1%), than clinically probable cases (60.6%, 44.4%, and 34.5% respectively), but differences between probable PD and ‘not PD’ cases were less evident. In cases not fulfilling criteria, the mean MDS UPDRS3 score (25.1, SD 13.2) was significantly higher than in probable PD (22.3, SD 12.7, p = 0.016) but not established PD (22.9, SD 12.0, p = 0.066). The l-dopa equivalent daily dose of 341 mg (SD 261) in non-PD cases was significantly higher than in probable PD (250 mg, SD 214, p < 0.001) and established PD (308 mg, SD 199, p = 0.025). After 30 months' follow-up, 89.5% of clinically established cases at baseline remained as PD (established/probable), and 86.9% of those categorized as clinically probable at baseline remained as PD (established/probable). Cases not fulfilling PD criteria had more severe parkinsonism, in particular relating to postural instability, gait problems, and cognitive impairment.
Conclusion:
Over 90% of cases clinically diagnosed as early PD fulfilled the MDS criteria for PD. Those not fulfilling criteria may have an atypical parkinsonian disorder or secondary parkinsonism that is not correctly identified by the UK Brain Bank criteria, but possibly by the new criteria
Alpha-Synuclein Oligomers Interact with Metal Ions to Induce Oxidative Stress and Neuronal Death in Parkinson's Disease
Protein aggregation and oxidative stress are both key pathogenic processes in Parkinson's disease, although the mechanism by which misfolded proteins induce oxidative stress and neuronal death remains unknown. In this study, we describe how aggregation of alpha-synuclein (α-S) from its monomeric form to its soluble oligomeric state results in aberrant free radical production and neuronal toxicity
Vascular disease and vascular risk factors in relation to motor features and cognition in early Parkinson's disease
Funded by Parkinson's UK National Institute for Health Research (NIHR) DeNDRoN network NIHR Newcastle Biomedical Research Unit Newcastle University NIHR funded Biomedical Research Centre in CambridgePeer reviewedPublisher PD
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