2,145 research outputs found
GOES-next navigation operations
The next generation of Geostationary Operational Environmental Satellites, GOES-I through -M (hereafter referred to as GOES-Next), begins a new era in the operation of weather satellites by the National Oceanic and Atmospheric Administration (NOAA). With a new spacecraft design, three-axis attitude stabilization, new ground support equipment, and improved methods of image navigation and registration that use on board compensation techniques to correct images for satellite motion, NOAA expects improved performance over the current series of dual-spin spacecraft. To meet these expectations, planning is currently underway for providing the complex and intensive operational environment that will meet the challenge of operating the GOES-Next spacecraft. This paper describes that operational environment
Estimation of an Examinee's Ability in the Web-Based Computerized Adaptive Testing Program IRT-CAT
We developed a program to estimate an examinee s ability in order to provide freely available access to a web-based computerized adaptive testing (CAT) program. We used PHP and Java Script as the program languages, PostgresSQL as the database management system on an Apache web server and Linux as the operating system. A system which allows for user input and searching within inputted items and creates tests was constructed. We performed an ability estimation on each test based on a Rasch model and 2- or 3-parametric logistic models. Our system provides an algorithm for a web-based CAT, replacing previous personal computer-based ones, and makes it possible to estimate an examinee's ability immediately at the end of test
Redox Modulating NRF2: A Potential Mediator of Cancer Stem Cell Resistance
Tumors contain a distinct small subpopulation of cells that possess stem cell-like characteristics. These cells have been called cancer stem cells (CSCs) and are thought to be responsible for anticancer drug resistance and tumor relapse after therapy. Emerging evidence indicates that CSCs share many properties, such as self-renewal and quiescence, with normal stem cells. In particular, CSCs and normal stem cells retain low levels of reactive oxygen species (ROS), which can contribute to stem cell maintenance and resistance to stressful tumor environments. Current literatures demonstrate that the activation of ataxia telangiectasia mutated (ATM) and forkhead box O3 (FoxO3) is associated with the maintenance of low ROS levels in normal stem cells such as hematopoietic stem cells. However, the importance of ROS signaling in CSC biology remains poorly understood. Recent studies demonstrate that nuclear factor-erythroid 2-related factor 2 (NRF2), a master regulator of the cellular antioxidant defense system, is involved in the maintenance of quiescence, survival, and stress resistance of CSCs. Here, we review the recent findings on the roles of NRF2 in maintenance of the redox state and multidrug resistance in CSCs, focusing on how NRF2-mediated ROS modulation influences the growth and resistance of CSCs
Mutual information and correlations across topological phase transitions in topologically ordered graphene zigzag nanoribbons
Graphene zigzag nanoribbons, initially in a topologically ordered state,
undergo a topological phase transition into crossover phases distinguished by
quasi-topological order. We computed mutual information for both the
topologically ordered phase and its crossover phases, revealing the following
results: (i) In the topologically ordered phase, A-chirality carbon lines
strongly entangle with B-chirality carbon lines on the opposite side of the
zigzag ribbon. This entanglement persists but weakens in crossover phases. (ii)
The upper zigzag edge entangles with non-edge lines of different chirality on
the opposite side of the ribbon. (iii) Entanglement increases as more carbon
lines are grouped together, regardless of the lines' chirality. No long-range
entanglement was found in the symmetry-protected phase in the absence of
disorder.Comment: A featured paper published in a special issue titled 'Entanglement
Entropy and Quantum Phase Transitions' within the journal 'Entropy'. (This is
the published version.
Coordinate d
We define the coordinate d-dimension print to distinguish sets of same fractal
dimension, and investigate its geometrical properties
Optical Spectroscopy of Supernova Remnants in M81 and M82
We present spectroscopy of 28 SNR candidates as well as one H II region in
M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn
out to be genuine SNRs, and two in M82 may be shocked condensations in the
galactic outflow or SNRs. The distribution of [N II]/H{\alpha} ratios of M81
SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line
ratio diagrams: an [O III]-strong group and an [O III]-weak group. The latter
have larger sizes, and may have faster shock velocity. [N II]/H{\alpha} ratios
of the SNRs show a strong correlation with [S II]/H{\alpha} ratios. They show a
clear radial gradient in [N II]/H{\alpha} and [S II]/H{\alpha} ratios: dLog ([N
II]/H{\alpha})/dLog R = -0.018 {\pm} 0.008 dex/kpc and dLog ([S
II]/H{\alpha})/dLog R = -0.016 {\pm} 0.008 dex/kpc where R is a deprojected
galactocentric distance. We estimate the nitrogen and oxygen abundance of the
SNRs from the comparison with shock-ionization models. We obtain a value for
the nitrogen radial gradient, dLog(N/H)/dLogR = -0.023 {\pm} 0.009 dex/kpc, and
little evidence for the gradient in oxygen. This nitrogen abundance shows a few
times flatter gradient than those of the planetary nebulae and H II regions. We
find that five SNRs are matched with X-ray sources. Their X-ray hardness colors
are consistent with thermal SNRs.Comment: 19 pages, 24 figures, 5 tables, ApJ accepte
Ginsenoside Rg3 Reduces Lipid Accumulation with AMP-Activated Protein Kinase (AMPK) Activation in HepG2 Cells
Cardiovascular disease (CVD) is one of the main causes of mortality worldwide, and dyslipidemia is a major risk factor for CVD. Ginseng has been widely used in the clinic to treat CVD. Ginsenoside Rg3, one of the major active components of ginseng, has been reported to exhibit antiobesity, antidiabetic, and cardioprotective effects. However, the effect of ginsenoside Rg3 on hepatic lipid metabolism remains unclear. Therefore, we investigated whether ginsenoside Rg3 would regulate hepatic lipid metabolism with AMP-activated protein kinase (AMPK) activation in HepG2 cells. Ginsenoside Rg3 significantly reduced hepatic cholesterol and triglyceride levels. Furthermore, ginsenoside Rg3 inhibited expression of sterol regulatory element binding protein-2 (SREBP-2) and 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGCR). Ginsenoside Rg3 increased activity of AMPK, a major regulator of energy metabolism. These results suggest that ginsenoside Rg3 reduces hepatic lipid accumulation with inhibition of SREBP-2 and HMGCR expression and stimulation of AMPK activity in HepG2 cells. Therefore, ginsenoside Rg3 may be beneficial as a food ingredient to lower the risk of CVD by regulating dyslipidemia
Phase Diagram and Crossover Phases of Topologically Ordered Graphene Zigzag Nanoribbons: Role of Localization Effects
We computed the phase diagram of the zigzag graphene nanoribbons as a
function of on-site repulsion, doping, and disorder strength. The topologically
ordered phase undergoes topological phase transitions into crossover phases,
which are new disordered phases with a nonuniversal topological entanglement
entropy with significant variance. The topological order is destroyed by
competition between localization effects and on-site repulsion. We found that
strong on-site repulsion and/or doping weakens the nonlocal correlations
between the opposite zigzag edges. In one of the crossover phases, both
fractional charges and spin-charge separation were absent;
however, charge-transfer correlations between the zigzag edges were possible.
Another crossover phase contains fractional charges, but no
charge transfer correlations. In low-doped zigzag ribbons the interplay between
electron localization and on-site repulsion contributes to the spatial
separation of quasi-degenerate gap-edge states and protects the charge
fractionalization against quantum fluctuations. In all these effects, mixed
chiral gap-edge states play an important role. The properties of nontopological
strongly disordered and strongly repulsive phases are also observed. Each phase
of the phase diagram has a different zigzag-edge structure
Observation of Competing Order in a High- Superconductor with Femtosecond Optical Pulses
We present studies of the photoexcited quasiparticle dynamics in
TlBaCaCuO (Tl-2223) using femtosecond optical
techniques. Deep into the superconducting state (below 40 K), a dramatic change
occurs in the temporal dynamics associated with photoexcited quasiparticles
rejoining the condensate. This is suggestive of entry into a coexistence phase
which, as our analysis reveals, opens a gap in the density of states (in
addition to the superconducting gap), and furthermore, competes with
superconductivity resulting in a depression of the superconducting gap.Comment: 5 pages, 3 figure
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