1,400 research outputs found
Keck and Gemini spectral characterization of Lucy mission fly-by target (152830) Dinkinesh
Recently, the inner main belt asteroid (152830) Dinkinesh was identified as
an additional fly-by target for the Lucy mission. The heliocentric orbit and
approximate absolute magnitude of Dinkinesh are known, but little additional
information was available prior to its selection as a target. In particular,
the lack of color spectrophotometry or spectra made it impossible to assign a
spectral type to Dinkinesh from which its albedo could be estimated. We set out
to remedy this knowledge gap by obtaining visible wavelength spectra with the
Keck telescope on 2022 November 23 and with Gemini-South on 2022 December 27.
The spectra measured with the Keck I/Low Resolution Imaging Spectrometer (LRIS)
and the Gemini South/Gemini Multi-Object Spectrograph South (GMOS-S) are most
similar to the average spectrum of S- and Sq-type asteroids. The most
diagnostic feature is the 151 silicate absorption feature at
0.9-1.0~micron. Small S- and Sq-type asteroids have moderately high
albedos ranging from 0.17-0.35. Using this albedo range for Dinkinesh in
combination with measured absolute magnitude, it is possible to derive an
effective diameter and surface brightness for this body. The albedo, size and
surface brightness are important inputs required for planning a successful
encounter by the Lucy spacecraft.Comment: 7 pages, 1 figure. Under review in Icaru
Evaluation of a Simplified Measurement for Low Glomerular Filtration Rates With lndium-111 DTPA
A rapid new method for measuring glomerular filtration rates using 111In diethylenetriamine pentaacetic acid (111In- DTPA) was evaluated with 39 patients who showed marked impairment of renal function (creatinine clearance less than 20 ml/min). A simple, single compartment system was assumed. For comparison, parallel inulin and creatinine clearances were performed. High linear correlations (r = 0.96-0.97) were demonstrated when 111In- DTPA clearances were compared with the standard nonisotopic tests. Initial data indicate that reliable isotopic clearance values could be obtained for low clearances by withdrawing only two blood samples for assay at 6 and 48 hours after isotope injection (without urine assay)
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Geologic Evaluation of Critical Production Parameters for Coalbed Methane Resources, Black Warrior Basin - Final Report
Characterization of coalbed methane occurrence and producibility in the Black Warrior basin of Alabama indicates that geologic factors are the principal controls on the occurrence and producibility of coalbed methane. Results of engineering analysis indicate that application of completion and stimulation techniques may be used to increase recovery once favorable well sites are chosen. Sedimentologic and coal-quality parameters may be used to locate regions for coalbed methane development by characterizing the occurrence, rank, and grade of coal resources. However, high-productivity trends within those regions are localized, and geologic data suggest that productivity trends may be predictable on the basis of structural and hydrologic parameters.
Several highly productive trends occur along northeast-oriented lineaments. These trends evidently are the surface expression of zones of enhanced permeability which apparently are related to fractures. Productive trends also are associated with areas of low reservoir pressure, and salinity maps indicate that fresh water has migrated toward these areas from the southeast margin of the basin. The available data indicate that structure and hydrology are critical production parameters that may be used to identify favorable well sites within regions containing significant, high-quality coal resources.Bureau of Economic Geolog
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Geologic Evaluation of Critical Production Parameters for Coalbed Methane Resources, Part II, Black Warrior Basin
Geologic evaluation of critical production parameters for coalbed-methane resources in the Black Warrior basin of Alabama employed an interdisciplinary approach that utilized structural, coal-quality, sedimentologic, hydrologic, and engineering data. Results indicate that geologic factors are a major control on the producibility of coalbed methane and that completion techniques may be used to increase recovery if tailored to specific geologic settings. Sedimentologic and coal-quality parameters may be used to locate regions for coalbed methane development by characterizing the occurrence, rank, and grade of coal resources. However, high-productivity trends within those regions are localized, and geologic data suggest that productivity trends may be predictable. Several highly productive trends occur along northeast-oriented lineaments. These lineaments are the inferred surface expression of zones of enhanced permeability which are related to fractures. Productive trends also are associated with areas of low reservoir pressure, and salinity maps indicate that fresh water has migrated toward areas with low reservoir pressure. The available data indicate that structure and hydrology are critical production parameters that may be used to identify favorable well sites within regions containing significant coalbed-methane resources.Bureau of Economic Geolog
SALVAGING VALUE FROM PROJECT FAILURE
PERFORMANCE CONSULTANTS SHOULD expect many of their improvement projects to fail. No one knows how many performance improvement projects fail, but DEFINING FAILURE Project failure is somewhat subjectively defined by the project manager and the project sponsor, but a strict definition of project failure would allow no deviations in the project schedule, budget, or scope
Structural Characterization of Pandoraea pnomenusa B-356 Biphenyl Dioxygenase Reveals Features of Potent Polychlorinated Biphenyl-Degrading Enzymes
The oxidative degradation of biphenyl and polychlorinated biphenyls (PCBs) is initiated in Pandoraea pnomenusa B-356 by biphenyl dioxygenase . , a heterohexameric Rieske oxygenase (RO), catalyzes the insertion of dioxygen with stereo- and regioselectivity at the 2,3-carbons of biphenyl, and can transform a broad spectrum of PCB congeners. Here we present the X-ray crystal structures of with and without its substrate biphenyl 1.6-Å resolution for both structures. In both cases, the Fe(II) has five ligands in a square pyramidal configuration: H233 Nε2, H239 Nε2, D386 Oδ1 and Oδ2, and a single water molecule. Analysis of the active sites of and related ROs revealed structural features that likely contribute to the superior PCB-degrading ability of certain BPDOs. First, the active site cavity readily accommodates biphenyl with minimal conformational rearrangement. Second, M231 was predicted to sterically interfere with binding of some PCBs, and substitution of this residue yielded variants that transform 2,2′-dichlorobiphenyl more effectively. Third, in addition to the volume and shape of the active site, residues at the active site entrance also apparently influence substrate preference. Finally, comparison of the conformation of the active site entrance loop among ROs provides a basis for a structure-based classification consistent with a phylogeny derived from amino acid sequence alignments
Towards Efficient Detection of Small Near-Earth Asteroids Using the Zwicky Transient Facility (ZTF)
We describe ZStreak, a semi-real-time pipeline specialized in detecting
small, fast-moving near-Earth asteroids (NEAs) that is currently operating on
the data from the newly-commissioned Zwicky Transient Facility (ZTF) survey.
Based on a prototype originally developed by Waszczak et al. (2017) for the
Palomar Transient Factory (PTF), the predecessor of ZTF, ZStreak features an
improved machine-learning model that can cope with the data rate
increment between PTF and ZTF. Since its first discovery on 2018 February 5
(2018 CL), ZTF/ZStreak has discovered confirmed new NEAs over a total of
232 observable nights until 2018 December 31. Most of the discoveries are small
NEAs, with diameters less than m. By analyzing the discovery
circumstances, we find that objects having the first to last detection time
interval under 2 hr are at risk of being lost. We will further improve
real-time follow-up capabilities, and work on suppressing false positives using
deep learning.Comment: PASP in pres
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