2,118 research outputs found
ELEVATED Î-FETOPROTEIN IN ASSOCIATION WITH LOSS OF SERUM HBeAg
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73663/1/j.1572-0241.1993.tb07621.x.pd
Temperate Eurasian Origins of Hawaiian Chenopodium (Amaranthaceae) plus description of a new species endemic to Molokaâi
Chenopodium taxa of Hawaiâi are tetraploids distinguished from other members of the circumglobally distributed genus by minute morphological characters. Because of these reasons, the geographic origin of Hawaiian Chenopodium has remained unclear. Across the Hawaiian Archipelago, Chenopodium taxa are morphologically variable and grow in highly disparate xeric habitats, especially in terms of precipitation, temperature, wind, salt spray, and solar irradiation. Habitats include dry subalpine shrublands, sandy beach strand of atolls in the Northwest Hawaiian Islands, dry forests, and precipitously tall sea cliffs of northwestern Molokaâi. From the Molokaâi sea cliffs, which are battered by high energy winds, salt spray, and strong seasonal precipitation, we describe C. oahuense subspecies ilioensis as segregated from the widespread Hawaiian C. oahuense s.l. Morphometric analyses distinguish C. oahuense ssp. ilioensis through its strongly prostrate to scandent habit, thick succulent leaves, smaller average leaf sizes, limited leaf margin lobing, and smaller seeds. Phylogenetic analyses using two DNA regions (the plastid gene rpl32-trnL and nuclear ITS1-5.85 rDNA-ITS2) of newly sequenced C. oahuense s.l. and C. oahuense ssp. ilioensis individuals plus outgroup taxa support monophyly of Hawaiian Chenopodium and reveal a geographic origin of temperate Eurasia. Two equivocal hypothetical scenarios are discussed regarding the likely sequence of events leading to the arrival of Chenopodium in Hawaiian Islands followed by possible in situ speciation of the Molokaâi endemic C. oahuense ssp. ilioensis
Search for correlation effects in linear chains of trapped ions
We report a precise search for correlation effects in linear chains of 2 and
3 trapped Ca+ ions. Unexplained correlations in photon emission times within a
linear chain of trapped ions have been reported, which, if genuine, cast doubt
on the potential of an ion trap to realize quantum information processing. We
observe quantum jumps from the metastable 3d 2D_{5/2} level for several hours,
searching for correlations between the decay times of the different ions. We
find no evidence for correlations: the number of quantum jumps with separations
of less than 10 ms is consistent with statistics to within errors of 0.05%; the
lifetime of the metastable level derived from the data is consistent with that
derived from independent single-ion data at the level of the experimental
errors 1%; and no rank correlations between the decay times were found with
sensitivity to rank correlation coefficients at the level of |R| = 0.024.Comment: With changes to introduction. 5 pages, including 4 figures. Submitted
to Europhys. Let
Cosmological perturbations on local systems
We study the effect of cosmological expansion on orbits--galactic, planetary,
or atomic--subject to an inverse-square force law. We obtain the laws of motion
for gravitational or electrical interactions from general relativity--in
particular, we find the gravitational field of a mass distribution in an
expanding universe by applying perturbation theory to the Robertson-Walker
metric. Cosmological expansion induces an ( force where
is the cosmological scale factor. In a locally Newtonian framework, we
show that the term represents the effect of a continuous
distribution of cosmological material in Hubble flow, and that the total force
on an object, due to the cosmological material plus the matter perturbation,
can be represented as the negative gradient of a gravitational potential whose
source is the material actually present. We also consider the effect on local
dynamics of the cosmological constant. We calculate the perihelion precession
of elliptical orbits due to the cosmological constant induced force, and work
out a generalized virial relation applicable to gravitationally bound clusters.Comment: 10 page
Single cell transcriptomics reveal polyclonal memory T cell responses in abacavir patch test positive skin
Capsule Summary. Single-cell responses in HLA-B*57:01 abacavir patch test positive skin remote to the acute hypersensitivity reaction demonstrate polyclonal T-cell activation and proliferation characterized by a transcriptional and cellular response consistent with memory responses to altered peptides
Full Flight Envelope Direct Thrust Measurement on a Supersonic Aircraft
Direct thrust measurement using strain gages offers advantages over analytically-based thrust calculation methods. For flight test applications, the direct measurement method typically uses a simpler sensor arrangement and minimal data processing compared to analytical techniques, which normally require costly engine modeling and multisensor arrangements throughout the engine. Conversely, direct thrust measurement has historically produced less than desirable accuracy because of difficulty in mounting and calibrating the strain gages and the inability to account for secondary forces that influence the thrust reading at the engine mounts. Consequently, the strain-gage technique has normally been used for simple engine arrangements and primarily in the subsonic speed range. This paper presents the results of a strain gage-based direct thrust-measurement technique developed by the NASA Dryden Flight Research Center and successfully applied to the full flight envelope of an F-15 aircraft powered by two F100-PW-229 turbofan engines. Measurements have been obtained at quasi-steady-state operating conditions at maximum non-augmented and maximum augmented power throughout the altitude range of the vehicle and to a maximum speed of Mach 2.0 and are compared against results from two analytically-based thrust calculation methods. The strain-gage installation and calibration processes are also described
Keeping a Single Qubit Alive by Experimental Dynamic Decoupling
We demonstrate the use of dynamic decoupling techniques to extend the
coherence time of a single memory qubit by nearly two orders of magnitude. By
extending the Hahn spin-echo technique to correct for unknown, arbitrary
polynomial variations in the qubit precession frequency, we show analytically
that the required sequence of pi-pulses is identical to the Uhrig dynamic
decoupling (UDD) sequence. We compare UDD and CPMG sequences applied to a
single Ca-43 trapped-ion qubit and find that they afford comparable protection
in our ambient noise environment.Comment: 5 pages, 5 figure
Effectively Measuring Exercise-Related Variations in T1Ï and T2 Relaxation Times of Healthy Articular Cartilage.
BACKGROUND: Determining the compositional response of articular cartilage to dynamic joint-loading using MRI may be a more sensitive assessment of cartilage status than conventional static imaging. However, distinguishing the effects of joint-loading vs. inherent measurement variability remains difficult, as the repeatability of these quantitative methods is often not assessed or reported. PURPOSE: To assess exercise-induced changes in femoral, tibial, and patellar articular cartilage composition and compare these against measurement repeatability. STUDY TYPE: Prospective observational study. POPULATION: Phantom and 19 healthy participants. FIELD STRENGTH/SEQUENCE: 3T; 3D fat-saturated spoiled gradient recalled-echo; T1Ï - and T2 -prepared pseudosteady-state 3D fast spin echo. ASSESSMENT: The intrasessional repeatability of T1Ï and T2 relaxation mapping, with and without knee repositioning between two successive measurements, was determined in 10 knees. T1Ï and T2 relaxation mapping of nine knees was performed before and at multiple timepoints after a 5-minute repeated, joint-loading stepping activity. 3D surface models were created from patellar, femoral, and tibial articular cartilage. STATISTICAL TESTS: Repeatability was assessed using root-mean-squared-CV (RMS-CV). Using Bland-Altman analysis, thresholds defined as the smallest detectable difference (SDD) were determined from the repeatability data with knee repositioning. RESULTS: Without knee repositioning, both surface-averaged T1Ï and T2 were very repeatable on all cartilage surfaces, with RMS-CVâSDD) average exercise-induced in T1Ï and T2 of femoral (-8.0% and -5.3%), lateral tibial (-6.9% and -5.9%), medial tibial (+5.8% and +2.9%), and patellar (-7.9% and +2.8%) cartilage were observed. DATA CONCLUSION: Joint-loading with a stepping activity resulted in T1Ï and T2 changes above background measurement error. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY STAGE: 1 J. MAGN. RESON. IMAGING 2020;52:1753-1764.GlaxoSmithKline
National Institute of Health Research (NIHR) Cambridge Biomedical Research Centr
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