76,760 research outputs found
Direct comparison of distinct naive pluripotent states in human embryonic stem cells
Until recently, human embryonic stem cells (hESCs) were shown to exist in a state of primed pluripotency, while mouse embryonic stem cells (mESCs) display a naive or primed pluripotent state. Here we show the rapid conversion of in-house-derived primed hESCs on mouse embryonic feeder layer (MEF) to a naive state within 5-6 days in naive conversion media (NCM-MEF), 6-10 days in naive human stem cell media (NHSM-MEF) and 14-20 days using the reverse-toggle protocol (RT-MEF). We further observe enhanced unbiased lineage-specific differentiation potential of naive hESCs converted in NCM-MEF, however, all naive hESCs fail to differentiate towards functional cell types. RNA-seq analysis reveals a divergent role of PI3K/AKT/mTORC signalling, specifically of the mTORC2 subunit, in the different naive hESCs. Overall, we demonstrate a direct evaluation of several naive culture conditions performed in the same laboratory, thereby contributing to an unbiased, more in-depth understanding of different naive hESCs
Cosmological Constraints on the Modified Entropic Force Model
Very recently, Verlinde considered a theory in which space is emergent
through a holographic scenario, and proposed that gravity can be explained as
an entropic force caused by changes in the information associated with the
positions of material bodies. Then, motivated by the Debye model in
thermodynamics which is very successful in very low temperatures, Gao modified
the entropic force scenario. The modified entropic force (MEF) model is in fact
a modified gravity model, and the universe can be accelerated without dark
energy. In the present work, we consider the cosmological constraints on the
MEF model, and successfully constrain the model parameters to a narrow range.
We also discuss many other issues of the MEF model. In particular, we clearly
reveal the implicit root to accelerate the universe in the MEF model.Comment: 16 pages, 7 figures, revtex4; v2: discussions added, Phys. Lett. B in
press; v3: published versio
Strong interfacial exchange field in the graphene/EuS heterostructure
Exploiting 2D materials for spintronic applications can potentially realize
next-generation devices featuring low-power consumption and quantum operation
capability. The magnetic exchange field (MEF) induced by an adjacent magnetic
insulator enables efficient control of local spin generation and spin
modulation in 2D devices without compromising the delicate material structures.
Using graphene as a prototypical 2D system, we demonstrate that its coupling to
the model magnetic insulator (EuS) produces a substantial MEF (> 14 T) with
potential to reach hundreds of Tesla, which leads to orders-of-magnitude
enhancement in the spin signal originated from Zeeman spin-Hall effect.
Furthermore, the new ferromagnetic ground state of Dirac electrons resulting
from the strong MEF may give rise to quantized spin-polarized edge transport.
The MEF effect shown in our graphene/EuS devices therefore provides a key
functionality for future spin logic and memory devices based on emerging 2D
materials in classical and quantum information processing
Modeling heat transfer in dilute two-phase flows using the Mesoscopic Eulerian Formalism
In dilute two-phase flows, accurate prediction of the temperature of the dis- persed phase can be of paramount importance. Indeed, processes such as evaporation or chemical reactions are strongly non-linear functions of heat transfer between the carrier and dispersed phases. This study is devoted to the validation of an Eulerian description of the dispersed phase –the Meso- scopic Eulerian Formalism (MEF)– in the case of non-isothermal flows. Di- rect numerical simulations using the MEF are compared to a reference La- grangian simulation for a two-dimensional non-isothermal turbulent jet laden with solid particles. The objectives of this paper are (1) to study the influ- ence of the thermal inertia of particles on their temperature distribution and (2) conduct an a posteriori validation of the MEF, which was recently ex- tended to non-isothermal flows. The focus is on the influence of additional terms in the MEF governing equations, namely heat fluxes arising from the Random Uncorrelated Motion (RUM). Results show that mean and rms of particle temperature are strongly dependent of the thermal Stokes number. The mean temperature is satisfactorily predicted by the MEF, comparing to the Lagrangian reference. Under the conditions of the present study, the RUM heat fluxes have a marginal influence on the mean particle tempera- ture. However, a significant impact was observed on the magnitude of particle temperature fluctuations. Neglecting the RUM heat fluxes leads to erroneous results while the Lagrangian statistics are recovered when it is accounted for in the regimes of low to moderate thermal Stokes number
MEF Üniversitesi Akademik / Kurumsal Arşiv Sistemi Yönergesi
MEF Üniversitesi Akademik / Kurumsal Arşiv Yönergesi, öğretim elemanlarının araştırmalarının ve entellektüel ürünlerinin erişilebilirliğini, görünürlüğünü, kullanımını ve etkisini artırmak; araştırmalardan üretilen yayınları daha etkin yönetebilmek ve kamu kaynaklarıyla desteklenen araştırmalardan üretilen yayınlara serbestçe erişimi desteklemek amacıyla geliştirilmiştir. Bu yönerge, MEF Üniversitesi adresli bilimsel çalışmaların, MEF Üniversitesi Akademik/Kurmsal Sistemin'de arşivlenerek bilim dünyasının hizmetine sunulmasına ilişkin usul ve esasları düzenler
Multi-element fiber technology for space-division multiplexing applications
A novel technological approach to space division multiplexing (SDM) based on the use of multiple individual fibers embedded in a common polymer coating material is presented, which is referred to as Multi-Element Fiber (MEF). The approach ensures ultralow crosstalk between spatial channels and allows for cost-effective ways of realizing multi-spatial channel amplification and signal multiplexing/demultiplexing. Both the fabrication and characterization of a passive 3-element MEF for data transmission, and an active 5-element erbium/ytterbium doped MEF for cladding-pumped optical amplification that uses one of the elements as an integrated pump delivery fiber is reported. Finally, both components were combined to emulate an optical fiber network comprising SDM transmission lines and amplifiers, and illustrate the compatibility of the approach with existing installed single-mode WDM fiber systems
Nanowire-Intensified MEF in Hybrid Polymer-Plasmonic Electrospun Filaments
Hybrid polymer-plasmonic nanostructures might combine high enhancement of
localized fields from metal nanoparticles with light confinement and long-range
transport in subwavelength dielectric structures. Here we report on the complex
behavior of fluorophores coupling to Au nanoparticles within polymer nanowires,
which features localized metal-enhanced fluorescence (MEF) with unique
characteristics compared to conventional structures. The intensification effect
when the particle is placed in the organic filaments is remarkably higher with
respect to thin films of comparable thickness, thus highlighting a specific,
nanowire-related enhancement of MEF effects. A dependence on the confinement
volume in the dielectric nanowire is also evidenced, with MEF significantly
increasing upon reducing the wire diameter. These findings are rationalized by
finite element simulations, predicting a position-dependent enhancement of the
quantum yield of fluorophores embedded in the fibers. Calculation of the
ensemble-averaged fluorescence enhancement unveils the possibility of strongly
enhancing the overall emission intensity for structures with size twice the
diameter of the embedded metal particles. These new, hybrid fluorescent systems
with localized enhanced emission, as well as the general Nanowire-Intensified
MEF effect associated to them, are highly relevant for developing nanoscale
light-emitting devices with high efficiency and inter-coupled through nanofiber
networks, highly sensitive optical sensors, and novel laser architectures.Comment: 29 pages, 12 figures, Small (2018
Testing microelectronic biofluidic systems
According to the 2005 International Technology Roadmap for Semiconductors, the integration of emerging nondigital CMOS technologies will require radically different test methods, posing a major challenge for designers and test engineers. One such technology is microelectronic fluidic (MEF) arrays, which have rapidly gained importance in many biological, pharmaceutical, and industrial applications. The advantages of these systems, such as operation speed, use of very small amounts of liquid, on-board droplet detection, signal conditioning, and vast digital signal processing, make them very promising. However, testable design of these devices in a mass-production environment is still in its infancy, hampering their low-cost introduction to the market. This article describes analog and digital MEF design and testing method
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