197 research outputs found
Successful reprogramming of epiblast stem cells by blocking nuclear localization of β-catenin.
Epiblast stem cells (EpiSCs) in mice and rats are primed pluripotent stem cells (PSCs). They barely contribute to chimeric embryos when injected into blastocysts. Reprogramming of EpiSCs to embryonic stem cell (ESC)-like cells (rESCs) may occur in response to LIF-STAT3 signaling; however, low reprogramming efficiency hampers potential use of rESCs in generating chimeras. Here, we describe dramatic improvement of conversion efficiency from primed to naive-like PSCs through upregulation of E-cadherin in the presence of the cytokine LIF. Analysis revealed that blocking nuclear localization of β-CATENIN with small-molecule inhibitors significantly enhances reprogramming efficiency of mouse EpiSCs. Although activation of Wnt/β-catenin signals has been thought desirable for maintenance of naive PSCs, this study provides the evidence that inhibition of nuclear translocation of β-CATENIN enhances conversion of mouse EpiSCs to naive-like PSCs (rESCs). This affords better understanding of gene regulatory circuits underlying pluripotency and reprogramming of PSCs
Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016
Infrasound waves detected in Antarctica contain information on the physical interaction among the surface environment at the margin of the continent and surrounding ocean. Time-space variation of source location for infrasound excitation during mid-April 2016 was investigated by using a combination of two arrays deployed along the coast of the Lützow-Holm Bay (LHB), East Antarctica. The infrasound array observations detected temporal variations in distance from the sources and propagation direction. A few tens of infrasound events were identified during 10 days of the period, and many of them located in the northward direction from the array stations were inside the LHB and offshore in the Southern Indian Ocean. Many of the events had predominant frequency content of few Hz, which were higher than microbaroms generated from the ocean. By comparing with MODIS satellite image at the same period, these sources were considered to be the ice-related phenomenon associated with the discharge of fast sea ice from the LHB
Experimental Test of a New Equality: Measuring Heat Dissipation in an Optically Driven Colloidal System
Measurement of energy dissipation in small nonequilibrium systems is
generally a difficult task. Recently, Harada and Sasa [Phys.Rev.Lett. 95,
130602(2005)] derived an equality relating the energy dissipation rate to
experimentally accessible quantities in nonequilibrium steady states described
by the Langevin equation. Here, we show the first experimental test of this new
relation in an optically driven colloidal system. We find that this equality is
validated to a fairly good extent, thus the irreversible work of a small system
is estimated from readily obtainable quantities.Comment: 4 pages, 6 figure
Locating earthquakes around Antarctica by using neural networks based on deep learning
The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researc
Elastic Convection in Vibrated Viscoplastic Fluids
We observe a new type of behavior in a shear thinning yield stress fluid:
freestanding convection rolls driven by vertical oscillation. The convection
occurs without the constraint of container boundaries yet the diameter of the
rolls is spontaneously selected for a wide range of parameters. The transition
to the convecting state occurs without hysteresis when the amplitude of the
plate acceleration exceeds a critical value. We find that a non-dimensional
stress, the stress due to the inertia of the fluid normalized by the yield
stress, governs the onset of the convective motion.Comment: 4 pages, 6 figure
Calibration of CRL all-sky imagers using an integrating sphere
As part of an international collaboration with the Geophysical Institute of the University of Alaska, we have developed two all-sky imagers (CRL-ASIs). A sensitivity calibration of the CRL-ASIs was performed using an integrating sphere belonging to the National Institute of Polar Research (NIPR). The two-dimensional sensitivities of the CRL-ASIs produced symmetrical distributions. Using this sensitivity data, we converted airglow/aurora images into two-dimensional distributions of absolute intensity. The sensitivity of the CRL-ASIs was measured for 13 wavelengths between 427.8 nm and 866.5 nm, and the relationship between the sensitivity and the wavelength was investigated for both imagers. The peak sensitivity occurred at about 550 nm
Nonlinear Elasticity of Single Collapsed Polyelectrolytes
Nonlinear elastic responses of short and stiff polyelectrolytes are
investigated by dynamic simulations on a single molecule level. When a
polyelectrolyte condensate undergoes a mechanical unfolding, two types of
force-extension curves, i.e., a force plateau and a stick-release pattern, are
observed depending on the strength of the electrostatic interaction. We provide
a physical interpretation of such force-extension behavior in terms of
intramolecular structures of the condensates. We also describe a charge
distribution of condensed counterions onto a highly stretched polyelectrolyte,
which clarifies a formation of one-dimensional strongly correlated liquid at
large Coulomb coupling regime where a stick-release pattern is observed. These
findings may provide significant insights into the relationship between a
molecular elasticity and a molecular mechanism of like-charge attractions
observed in a wide range of charged biopolymer systems.Comment: 5pages, 5figure
A Realistic Extension of Gauge-Mediated SUSY-Breaking Model with Superconformal Hidden Sector
The sequestering of supersymmetry (SUSY) breaking parameters, which is
induced by superconformal hidden sector, is one of the solutions for the
mu/B_mu problem in gauge-mediated SUSY-breaking scenario. However, it is found
that the minimal messenger model does not derive the correct electroweak
symmetry breaking. In this paper we present a model which has the coupling of
the messengers with the SO(10) GUT-symmetry breaking Higgs fields. The model is
one of the realistic extensions of the gauge mediation model with
superconformal hidden sector. It is shown that the extension is applicable for
a broad range of conformality breaking scale.Comment: 15 pages, 2 figures, 1 tabl
Associations of sedentary and physically-active behaviors with cognitive-function decline in community-dwelling older adults: compositional data analysis from the NEIGE study
BACKGROUND: Physical activity can help to protect against cognitive decline in older adults. However, little is known about the potential combined relationships of time spent in sedentary behavior (SB), light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with indices of cognitive health. We examined the cross-sectional associations of objectively-determined sedentary and physically-active behaviors with an indicator of cognitive function decline (CFD) in older adults.
METHODS: A randomly-recruited sample of 511 Japanese older adults (47% male; aged 65-84 years) wore a tri-axial accelerometer (HJA-750C, Omron) for seven consecutive days in 2017. Cognitive function was assessed by interviewers using the Japanese version of Mini-Mental State Examination, with a score of ≤23 indicating CFD. Associations of sedentary and physically-active behaviors with CFD were examined using a compositional logistic regression analysis based on isometric log-ratio transformations of time use, adjusting for potential confounders.
RESULTS: Forty one (9.4%) of the participants had an indication of CFD. Activity compositions differed significantly between CFD and normal cognitive function (NCF); the proportion of time spent in MVPA was 39.1% lower, relatively to the overall mean composition in those with CFD, and was 5.3% higher in those with NCF. There was a significant beneficial association of having a higher proportion of MVPA relative to other activities with CFD. LPA and SB were not associated with CFD when models were corrected for time spent in all activity behaviors.
CONCLUSIONS: Larger relative contribution of MVPA was favorably associated with an indicator of CFD in older adults
Changes in rural older adults' sedentary and physically-active behaviors between a non-snowfall and a snowfall season: compositional analysis from the NEIGE study
BackgroundLevels of physical activity change throughout the year. However, little is known to what extent activity levels can vary, based on accelerometer determined sedentary and physically-active time. The aim of this longitudinal study was to examine older adults' activity changes from a non-snowfall season to a subsequent snowfall season, with consideration of the co-dependence of domains of time use.MethodsParticipants were 355 older Japanese adults (53.1% women, aged 65-84years) living in a rural area of heavy snowfall who had valid accelerometer (Active style Pro HJA-750C) data during non-snowfall and snowfall seasons. Activity was classified as sedentary behavior (SB), light-intensity PA (LPA), and moderate-to-vigorous PA (MVPA). Compositional changes from the non-snowfall to the snowfall season were analyzed using Aitchison's perturbation method. The ratios of each component in the composition, such as [SBsnow/SBnon-snow, LPAsnow/LPAnon-snow, MVPAsnow/MVPAnon-snow] for seasonal changes, were calculated and were then divided by the sum of these ratios.ResultsIn men, the percentages of time spent in each activity during the non-snowfall/snowfall seasons were 53.9/64.6 for SB; 40.8/31.6 for LPA; and 5.3/3.8 for MVPA; these corresponded to mean seasonal compositional changes (SB, LPA, MVPA) of 0.445, 0.287, and 0.268 respectively. In women, the percentages of time spent in each activity during the non-snowfall/snowfall seasons were 47.9/55.5 for SB; 47.9/41.0 for LPA; and 4.2/3.5 for MVPA; these corresponded to mean seasonal compositional changes (SB, LPA, MVPA) of 0.409, 0.302, and 0.289 respectively. The degree of seasonal change was greatest in men.ConclusionsIn older adults, activity behaviors were changed unfavorably during snowfall season, particularly so for men. The degree of seasonal change was greatest for SB. Development of strategies to keep rural older adults active during the snowfall season may be needed for maintaining a consistently-active lifestyle for their health
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