The Johns Hopkins University Applied Physics Laboratory (APL) is working to realize a variety of nanostructured designs via top-down nanofabrication techniques. We leverage electron beam lithography, ...nanoimprint lithography, and focused ion beam deposition to pattern nanoscale features on semiconductor and optical material substrates. We combine these with other traditional microfabrication techniques as well as a few unique ones, including an atomic layer deposition–enabled nanomolding process to create high-aspect-ratio nanopillars from materials such as titanium dioxide (TiO2). We apply these techniques on a wide variety of nontraditional substrate and film materials, including optical, phase-change, and superconducting materials, to create novel optical and electronic devices.
2-D Electrostatic Actuation of Microshutter Arrays Burns, Devin E.; Oh, Lance H.; Li, Mary J. ...
Journal of microelectromechanical systems,
2016-Feb., 2016-2-00, 20160201, Volume:
25, Issue:
1
Journal Article
Peer reviewed
Electrostatically actuated microshutter arrays consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and ...experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. The analysis of the resonant behavior of the microshutters demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25 V. The 2-D electrostatic latching and addressing was demonstrated using both a resonant and a pulsed addressing scheme.
An electrostatically actuated microshutter array consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and ...experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters, while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. Analysis of the resonant behavior of the microshutter arrays demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25V. 2D electrostatic latching and addressing was demonstrated using both a resonant and pulsed addressing scheme.
Small changes in the radiation budget at the earth's surface can lead to large climatological responses when persistent over time. With the increasing debate on anthropogenic influences on climatic ...processes during the 1980s the need for accurate radiometric measurements with higher temporal resolution was identified, and it was determined that the existing measurement networks did not have the resolution or accuracy required to meet this need. In 1988 the WMO therefore proposed the establishment of a new international Baseline Surface Radiation Network (BSRN), which should collect and centrally archive high-quality ground-based radiation measurements in 1 min resolution. BSRN began its work in 1992 with 9 stations; currently (status 2018-01-01), the network comprises 59 stations (delivering data to the archive) and 9 candidates (stations recently accepted into the network with data forthcoming to the archive) distributed over all continents and oceanic environments. The BSRN database is the World Radiation Monitoring Center (WRMC). It is hosted at the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, and now offers more than 10 300 months of data from the years 1992 to 2017. All data are available at https://doi.org/10.1594/PANGAEA.880000 free of charge.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Purpose: To further assess preclinical and early clinical evidence that imatinib mesylate, a platelet-derived growth factor receptor
(PDGFR) inhibitor, modulates taxane activity in prostate cancer ...and bone metastases, a randomized study was conducted.
Experimental Design: Men with progressive castration-resistant prostate cancer with bone metastases ( n = 144) were planned for equal randomization to i.v. 30 mg/m 2 docetaxel on days 1, 8, 15, and 22 every 42 days with 600 mg imatinib daily or placebo, for an improvement in median progression-free
survival from 4.5 to 7.5 months (two-sided α = 0.05 and β = 0.20). Secondary end points included differential toxicity and bone turnover markers, tumor phosphorylated PDGFR (p-PDGFR)
expression, and modulation of p-PDGFR in peripheral blood leukocytes.
Results: Accrual was halted early because of adverse gastrointestinal events. Among 116 evaluable men (57 docetaxel + imatinib; 59
docetaxel + placebo), respective median times to progression were 4.2 months (95% confidence interval, 3.1-7.5) and 4.2 months
(95% confidence interval, 3.0-6.8; P = 0.58, log-rank test). Excess grade 3 toxicities ( n = 23) in the docetaxel + imatinib group were principally fatigue and gastrointestinal. Tumor p-PDGFR expression was observed
in 12 of 14 (86%) evaluable bone specimens. In peripheral blood leukocytes, p-PDGFR reduction was more likely in docetaxel
+ imatinib–treated patients compared with docetaxel + placebo ( P < 0.0001), as were reductions in urine N-telopeptides ( P = 0.004) but not serum bone-specific alkaline phosphatase ( P = 0.099).
Conclusions: These clinical and translational results question the value of PDGFR inhibition with taxane chemotherapy in prostate cancer
bone metastases and are at variance with the preclinical studies. This discordance requires explanation.
Pruned Multiangle Resolution Fast Beamforming Yoon, Yeo-Sun; Kaplan, Lance M.; Oh, Seung-Mok ...
EURASIP Journal on Advances in Signal Processing,
01/2008, Volume:
2008, Issue:
1
Journal Article
Peer reviewed
Open access
Delay-and-sum (DS) beamforming is a simple processing method that can estimate the direction-of-arrival from multiple signal sources. The major advantage of DS beamforming is that it can handle ...wideband as well as narrowband signals. However, DS beamforming exhibits high computational complexity. The multiangle resolution fast beamformer was proposed as a computationally efficient approximation of DS beamforming, reducing the computational order of complexity from
to
. In this paper, we introduce the
pruned
multiangle resolution fast beamformer to further reduce the computational complexity. The new algorithm includes an energy detector at intermediate stages of the fast beamformer to prune sectors that do not exhibit increasing energy consistent with coherent integration. Simulations are provided to assess the performance of the pruned fast beamformer. One use for the estimates from the pruned fast beamformer is to initialize high-resolution direction-of-arrival (DOA) estimators such as coherent signal subspace methods.
Standard radar image formation techniques waste computational resources by full resolving all areas of the scene, even regions of benign clutter. We introduce a multiscale prescreener algorithm that ...runs as part of the image formation processing step for ultrawideband (UWB) synthetic aperture radar (SAR) systems. The prescreener processes intermediate radar data generated by a quadtree backprojection image former. As the quadtree algorithm iterates, it is resolving increasingly finer subpatches of the scene. After each quadtree stage, the prescreener makes an estimate of the signal-to-background ratio of each subpatch and applies a constant false alarm rate (CFAR) detector to decide which ones might contain a target of interest. Whenever the prescreener determines that a subpatch is not near a detection, it cues the image former to terminate further processing of that subpatch. Using a small database of UWB radar field data, we demonstrate that the prescreener is able to decrease the overall computational load of the image formation process. We also show that the new multiscale prescreener method produces fewer false alarms than the conventional two-parameter CFAR prescreener applied to the completely formed image.
The Delmarva fox squirrel, Sciurus niger cinereus, is a federally listed endangered subspecies whose range has been reduced by 90%. In an attempt to increase both population size and range, ...translocation sites were established beginning in the 1960's by moving squirrels from the natural range to sites outside the current range. Although translocations have served as the primary component of the DFS recovery program, there has been very little post-release examination of the genetics of the translocation sites. In this study, we developed ten microsatellite loci, screened the three polymorphic loci, and sequenced a 330 bp fragment of the mitochondrial control region in order to assess levels of genetic variation in natural and translocated regions of Delmarva fox squirrels and to compare them to Southeastern fox squirrels (S. n. niger). Although we found low levels of microsatellite polymorphism, there were no differences in heterozygosity between natural and translocated regions, or between Delmarva and Southeastern fox squirrels. We found high levels of polymorphism in the mitochondrial control region. Our patterns of haplotype diversity suggest incomplete lineage sorting of the two subspecies. In general, our data suggest that the current levels of genetic variation in the translocated sites are representative of those found in the natural population, and we encourage the continued use of translocations as a major component of Delmarva fox squirrel recovery.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
10.
Pruned Multiangle Resolution Fast Beamforming YOON, Yeo-Sun; KAPLAN, Lance M; OH, Seung-Mok ...
EURASIP journal on advances in signal processing,
2008, Volume:
2008, Issue:
12
Journal Article
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