44 research outputs found
Fermionic zero modes in self-dual vortex background
We study fermionic zero modes in the background of self-dual vortex on a
two-dimensional non-compact extra space in 5+1 dimensions. In the Abelian Higgs
model, we present an unified description of the topological and non-topological
self-dual vortex on the extra two dimensions. Based on it, we study
localization of bulk fermions on a brane with inclusion of Yang-Mills and
gravity backgrounds in six dimensions. Through two simple cases, it is shown
that the vortex background contributes a phase shift to the fermionic zero
mode, this phase is actually origin from the Aharonov-Bohm effect.Comment: 11 pages, no figures, to appear in MPL
Observational quantification of three-dimensional anisotropies and scalings of space plasma turbulence at kinetic scales
A statistical survey of spectral anisotropy of space plasma turbulence is
performed using five years measurements from MMS in the magnetosheath. By
measuring the five-point second-order structure functions of the magnetic
field, we have for the first time quantified the three-dimensional anisotropies
and scalings at sub-ion-scales ( 100 km). In the local reference frame
defined with respect to
local mean magnetic field (Chen et al. 2012), the
"statistical eddies" are found to be mostly elongated along
and shortened in the direction perpendicular to both and
local field fluctuations. From several (ion inertial length) toward
0.05 , the ratio between eddies' parallel and perpendicular lengths
features a trend of rise then fall, whereas the anisotropy in the perpendicular
plane appears scale-invariant. Specifically, the anisotropy relations for the
total magnetic field at 0.1-1.0 are obtained as , and , respectively. Our results provide new observational evidence
to compare with phenomenological models and numerical simulations, which may
help to better understand the nature of kinetic scale turbulence.Comment: Accepte
Efficient Energy Conversion through Vortex Arrays in the Turbulent Magnetosheath
Turbulence is often enhanced when transmitted through a collisionless plasma shock. We investigate how the enhanced turbulent energy in the Earth's magnetosheath effectively dissipates via vortex arrays. This research topic is of great importance as it relates to particle energization at astrophysical shocks across the universe. Wave modes and intermittent coherent structures are the key candidate mechanisms for energy conversion in turbulent plasmas. Here, by comparing in-situ measurements in the Earth's magnetosheath with a theoretical model, we find the existence of vortex arrays at the transition between the downstream regions of the Earth's bow shock. Vortex arrays consist of quasi-orthogonal kinetic waves and exhibit both high volumetric filling factors and strong local energy conversion, thereby showing a greater dissipative energization than traditional waves and coherent structures. Therefore, we propose that vortex arrays are a promising mechanism for efficient energy conversion in the sheath regions downstream of astrophysical shocks
Shape stabilization and laser triggered shape transformation of magnetic particle functionalized liquid metal motors
Liquid metal motors made from biologically benign gallium are promising candidates for various applications ranging from drug delivery to targeting and killing cancer cells directly. One of the main problems with this novel technology is the need to utilize a membrane, making it possible to maintain a defined shape in order to perform the required functions. For magnetic remote guidance, liquid metal motors can be doped with magnetic iron microparticles, forming a transition magnetic liquid. In an alternative approach liquid metal structures are coated with magnetite nanoparticles. We hereby present an approach to laminate biologically benign gallium-based magnetic liquid metal motors with a biodegradable and biocompatible macromolecular thin film to retain the initial shape. Thanks to the polymer lamination and by the help of magnetic fields, the presented liquid metal motors can be remotely guided. The shape retaining macromolecular thin film can be liquefied by photothermal effects such as laser irradiation in order to change the shape of the liquid metal motor into a droplet due to surface energy minimization, allowing for penetration of structures smaller than the initial motor size. This work uses a relatively large technical demonstrator to show the technical realization and properties of this novel system, which opens up new paths and potential applications
Superfast Near-Infrared Light-Driven Polymer Multilayer Rockets
A gold nanoshell-functionalized polymer multilayer nanorocket performs self-propulsion upon the irradiation with NIR light in the absence of chemical fuel. Theoretical simulations reveal that the NIR light-triggered self-thermophoresis drives the propulsion of the nanorocket. The nanorocket also displays efficient NIR light-triggered propulsion in biofluids and thus holds considerable promise for various potential biomedical applications
Superfast Near-Infrared Light-Driven Polymer Multilayer Rockets
A gold nanoshell-functionalized polymer multilayer nanorocket performs self-propulsion upon the irradiation with NIR light in the absence of chemical fuel. Theoretical simulations reveal that the NIR light-triggered self-thermophoresis drives the propulsion of the nanorocket. The nanorocket also displays efficient NIR light-triggered propulsion in biofluids and thus holds considerable promise for various potential biomedical applications
miR-17/20 sensitization of breast cancer cells to chemotherapy-induced apoptosis requires Akt1.
The serine threonine kinase Akt1 has been implicated in the control of cellular metabolism, survival and growth. Herein, disruption of the ubiquitously expressed member of the Akt family of genes, Akt1, in the mouse, demonstrates a requirement for Akt1 in miRNA-mediated cellular apoptosis. The miR-17/20 cluster is known to inhibit breast cancer cellular proliferation through G1/S cell cycle arrest via binding to the cyclin D1 3\u27UTR. Here we show that miR-17/20 overexpression sensitizes cells to apoptosis induced by either Doxorubicin or UV irradiation in MCF-7 cells via Akt1. miR-17/20 mediates apoptosis via increased p53 expression which promotes Akt degradation. Akt1-/- mammary epithelial cells which express Akt2 and Akt3 demonstrated increased apoptosis to DNA damaging agents. Akt1 deficiency abolished the miR-17/20-mediated apoptosis. These results demonstrated a novel pathway through which miR17/20 regulate p53 and Akt controlling breast cancer cell apoptosis
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Multiband Electrostatic Waves below and above the Electron Cyclotron Frequency in the Near-Sun Solar Wind
Using the Parker Solar Probe measurements, this Letter reports two new types of multiband electrostatic waves in and near the heliospheric current sheet. They are classified into the f < fce and f > fce multiband electrostatic waves, in which most (or all) of the bands in the former type are lower than fce, and all of the bands in the latter type are higher than fce, where f and fce denotes the wave frequency and the electron cyclotron frequency, respectively. This Letter also exhibits observational evidence of the existence of nonlinear wave–wave interactions of both types of electrostatic waves. In particular, the f > fce multiband electrostatic waves are found to be modulated in the presence of low-frequency oblique ion-scale waves. According to the observed frequency distribution, this Letter proposes that the mode nature of the f < fce multiband electrostatic waves could be the oblique ion acoustic wave or the lower-hybrid wave, and the f > fce multiband electrostatic waves are the electron Bernstein mode wave. These findings provide a challenge to understand the complex electron and ion dynamical processes in and near the heliospheric current sheet.
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Whole-genome sequencing of <em>Oryza brachyantha</em> reveals mechanisms underlying <em>Oryza</em> genome evolution
The wild species of the genus Oryza contain a largely untapped reservoir of agronomically important genes for rice improvement. Here we report the 261-Mb de novo assembled genome sequence of Oryza brachyantha. Low activity of long-terminal repeat retrotransposons and massive internal deletions of ancient long-terminal repeat elements lead to the compact genome of Oryza brachyantha. We model 32,038 protein-coding genes in the Oryza brachyantha genome, of which only 70% are located in collinear positions in comparison with the rice genome. Analysing breakpoints of non-collinear genes suggests that double-strand break repair through non-homologous end joining has an important role in gene movement and erosion of collinearity in the Oryza genomes. Transition of euchromatin to heterochromatin in the rice genome is accompanied by segmental and tandem duplications, further expanded by transposable element insertions. The high-quality reference genome sequence of Oryza brachyantha provides an important resource for functional and evolutionary studies in the genus Oryza