1,930 research outputs found
Five Debris Disks Newly Revealed in Scattered Light from the HST NICMOS Archive
We have spatially resolved five debris disks (HD 30447, HD 35841, HD 141943,
HD 191089, and HD 202917) for the first time in near-infrared scattered light
by reanalyzing archival Hubble Space Telescope (HST)/NICMOS coronagraphic
images obtained between 1999 and 2006. One of these disks (HD 202917) was
previously resolved at visible wavelengths using HST/Advanced Camera for
Surveys. To obtain these new disk images, we performed advanced point-spread
function subtraction based on the Karhunen-Loeve Image Projection (KLIP)
algorithm on recently reprocessed NICMOS data with improved detector artifact
removal (Legacy Archive PSF Library And Circumstellar Environments Legacy
program). Three of the disks (HD 30447, HD 35841, and HD 141943) appear
edge-on, while the other two (HD 191089 and HD 202917) appear inclined. The
inclined disks have been sculpted into rings; in particular, the disk around HD
202917 exhibits strong asymmetries. All five host stars are young (8-40 Myr),
nearby (40-100 pc) F and G stars, and one (HD 141943) is a close analog to the
young sun during the epoch of terrestrial planet formation. Our discoveries
increase the number of debris disks resolved in scattered light from 19 to 23
(a 21% increase). Given their youth, proximity, and brightness (V = 7.2 to
8.5), these targets are excellent candidates for follow-up investigations of
planet formation at visible wavelengths using the HST/STIS coronagraph, at
near-infrared wavelengths with the Gemini Planet Imager (GPI) and Very Large
Telescope (VLT)/SPHERE, and at thermal infrared wavelengths with the James Webb
Space Telescope NIRCam and MIRI coronagraphs.Comment: 6 pages, 1 figure, 1 tabl
An Efficient Solution Method for Multibody Systems with Loops Using Multiple Processors
This paper describes a multibody dynamics algorithm formulated for parallel implementation on multiprocessor computing platforms using the divide-and-conquer approach. The system of interest is a general topology of rigid and elastic articulated bodies with or without loops. The algorithm divides the multibody system into a number of smaller sets of bodies in chain or tree structures, called "branches" at convenient joints called "connection points", and uses an Order-N (O (N)) approach to formulate the dynamics of each branch in terms of the unknown spatial connection forces. The equations of motion for the branches, leaving the connection forces as unknowns, are implemented in separate processors in parallel for computational efficiency, and the equations for all the unknown connection forces are synthesized and solved in one or several processors. The performances of two implementations of this divide-and-conquer algorithm in multiple processors are compared with an existing method implemented on a single processor
Microwave and Quantum Magnetics
Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Institutes of Health (Grant 1 P01 CA3 1303-01
Microwave and Quantum Magnetics
Contains research objectives and reports on five research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)National Institutes of Health (Grant 1 P01 CA3 1303-01
Human health risk assessment of temporal and spatial variations of ground water quality at a densely industrialized commercial complex at Haridwar, India
The observations of present investigation revealed that the groundwater regime at State Infrastructure and Industrial Development Corporation of Uttarakhand Limited (SIDCUL) Industrial Estate (IE) was highly responsive to the anthropogenic stress of recharge and discharge parameters concerning the distressing industrial activities. The present study on groundwater characteristics of SIDCUL-IE, Haridwar in year 2013-2014 showed that the water of Sampling station-D (SSD) had relatively poor quality in comparison to the groundwater collected from Sampling station-A (SSA), Sampling station-B (SSB) and Sampling station-C (SSC). The samples had a high mineral load with relatively wider pH range. The physico-chemical parameters like pH (6.35 in October) at SSA, TDS (553.5 mg/l in November) at SSC, TH (600.0 mg/l in July) at SSB and alkalinity (525.0 mg/l in October) at SSD were beyond the prescribed limits of Bureau of Indian Standards (BIS). The Karl Pearson correlation matrix showed moderate to significantly positive correlation between various parameters like COD-phosphorus (r=0.629), temperature-DO (r=-0.477) at SSA; pH and bicarbonate (r=0.668) at SSB; pH-temperature (r=-0.551),turbidity-BOD (r=0.467), BOD-phosphorus (r=0.518), bicarbonate-acidity (r=-0.833) at SSC and TSS-turbidity (r=0.616), BOD-COD (r=0.6771) at SSD and temperature-DO (r=-0.666), hardness-acidity (r=-0.6542) BOD-COD (r=0.654) at control site. The overall quality of groundwater, though hard, was found acceptable for drinking purpose. The divergence in the results of groundwater samples taken from SIDCUL-IE and the Control site, 2 km away from SIDCUL-IE, indicated that groundwater pollution is increasing alarmingly which may have serious threats to human health in near future
Microwave and Quantum Magnetics
Contains research objectives and reports on six research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020)Joint Services Electronics Program (Contract DAAG29-80-C-0104)United States Air Force (Contract F19628-79-C-0047
Two-color widefield fluorescence microendoscopy enables multiplexed molecular imaging in the alveolar space of human lung tissue
We demonstrate a fast two-color widefield fluorescence microendoscopy system capable of simultaneously detecting several disease targets in intact human ex vivo lung tissue. We characterize the system for light throughput from the excitation light emitting diodes, fluorescence collection efficiency, and chromatic focal shifts. We demonstrate the effectiveness of the instrument by imaging bacteria (Pseudomonas aeruginosa) in ex vivo human lung tissue. We describe a mechanism of bacterial detection through the fiber bundle that uses blinking effects of bacteria as they move in front of the fiber core providing detection of objects smaller than the fiber core and cladding (∼3 μm ∼3 μm ). This effectively increases the measured spatial resolution of 4 μm 4 μm . We show simultaneous imaging of neutrophils, monocytes, and fungus (Aspergillus fumigatus) in ex vivo human lung tissue. The instrument has 10 nM and 50 nM sensitivity for fluorescein and Cy5 solutions, respectively. Lung tissue autofluorescence remains visible at up to 200 fps camera acquisition rate. The optical system lends itself to clinical translation due to high-fluorescence sensitivity, simplicity, and the ability to multiplex several pathological molecular imaging targets simultaneously.</p
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