2,231 research outputs found
Erasure List-Decodable Codes from Random and Algebraic Geometry Codes
Erasure list decoding was introduced to correct a larger number of erasures
with output of a list of possible candidates. In the present paper, we consider
both random linear codes and algebraic geometry codes for list decoding erasure
errors. The contributions of this paper are two-fold. Firstly, we show that,
for arbitrary ( and are independent),
with high probability a random linear code is an erasure list decodable code
with constant list size that can correct a fraction
of erasures, i.e., a random linear code achieves the
information-theoretic optimal trade-off between information rate and fraction
of erasure errors. Secondly, we show that algebraic geometry codes are good
erasure list-decodable codes. Precisely speaking, for any and
, a -ary algebraic geometry code of rate from the
Garcia-Stichtenoth tower can correct
fraction of erasure errors with
list size . This improves the Johnson bound applied to algebraic
geometry codes. Furthermore, list decoding of these algebraic geometry codes
can be implemented in polynomial time
Transmission of sodium chloride in PDMS membrane during Pervaporation based on polymer relaxation
Polydimethylsiloxane (PDMS) composite membrane is used for treating pharmaceutical wastewater containing NaCl and solvent. In this study, the influence of feed concentrations of NaCl and isobutanol, process temperature and membrane microstructures on salt rejection are evaluated. Microstructures of PDMS membrane before and after separation are characterized by nuclear magnetic resonance (NMR), energy dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Positron annihilation life-time spectroscopy (PALS). The PV results show that NaCl will not spontaneously enter PDMS membrane without isobutanol. However, while NaCl feed concentration is 13 wt%, salt rejection of PDMS membrane drops from 100% to 99.09% with increasing feed concentration of isobutanol (up to 7 wt%). On the contrary, a higher temperature increases salt rejection of PDMS membrane and NaCl permeation through PDMS membrane is not through a vapor permeate process. Due to the relaxation of PDMS polymer chain, when PDMS cross-linking ratio is 0.1, the salt rejection increases from 99.87% to 100% with its thickness increasing from 10 ?m to 17.5 ?m. While the cross-linking ratio rises to 0.2, the salt rejection is 100% with the PDMS layer thickness of 10 ?m. The relationship between relaxation of polymer chains and transport of NaCl in PDMS membrane is an excellent guidance and will be beneficial for the treatment of saline organic wastewater
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Synergistic effect of phosphodiesterase 4 inhibitor and serum on migration of endotoxin-stimulated macrophages.
Macrophage migration is an essential step in host defense against infection and wound healing. Elevation of cAMP by inhibiting phosphodiesterase 4 (PDE4), enzymes that specifically degrade cAMP, is known to suppress various inflammatory responses in activated macrophages, but the role of PDE4 in macrophage migration is poorly understood. Here we show that the migration of Raw 264.7 macrophages stimulated with LPS was markedly and dose-dependently induced by the PDE4 inhibitor rolipram as assessed by scratch wound healing assay. Additionally, this response required the involvement of serum in the culture medium as serum starvation abrogated the effect. Further analysis revealed that rolipram and serum exhibited synergistic effect on the migration, and the influence of serum was independent of PDE4 mRNA expression in LPS-stimulated macrophages. Moreover, the enhanced migration by rolipram was mediated by activating cAMP/exchange proteins directly activated by cAMP (Epac) signaling, presumably via interaction with LPS/TLR4 signaling with the participation of unknown serum components. These results suggest that PDE4 inhibitors, together with serum components, may serve as positive regulators of macrophage recruitment for more efficient pathogen clearance and wound repair
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The Role of Chaperone-Mediated Autophagy in Huntingtin Degradation
Huntington Disease (HD) is caused by an abnormal expansion of polyQ tract in the protein named huntingtin (Htt). HD pathology is featured by accumulation and aggregation of mutant Htt in striatal and cortical neurons. Aberrant Htt degradation is implicated in HD pathogenesis. The aim of this study was to investigate the regulatory role of chaperone-mediated autophagy (CMA) components, heat shock protein cognate 70 (Hsc70) and lysosome-associated protein 2A (LAMP-2A) in degradation of Htt fragment 1-552aa (Htt-552). A cell model of HD was produced by overexpression of Htt-552 with adenovirus. The involvement of CMA components in degradation of Htt-552 was determined with over-expression or silencing of Hsc70 and LAMP-2A. The results confirmed previous reports that both macroautophagy and CMA were involved in degradation of Htt-552. Changing the levels of CMA-related proteins affected the accumulation of Htt-552. The lysosomal binding and luminal transport of Htt-552 was demonstrated by incubation of Htt-552 with isolated lysosomes. Expansion of the polyQ tract in Htt-552 impaired its uptake and degradation by lysosomes. Mutation of putative KFERQ motif in wild-type Htt-552 interfered with interactions between Htt-552 and Hsc70. Endogenous Hsc70 and LAMP-2A interacted with exogenously expressed Htt-552. Modulating the levels of CMA related proteins degraded endogenous full-length Htt. These studies suggest that Hsc70 and LAMP-2A through CMA play a role in the clearance of Htt and suggest a novel strategy to target the degradation of mutant Htt
High levels of solar radiation offset impacts of ocean acidification on calcifying and non-calcifying strains of Emiliania huxleyi
Coccolithophores, a globally distributed group of marine phytoplankton, showed diverse responses to ocean acidification (OA) and to combinations of OA with other environmental factors. While their growth can be enhanced and calcification be hindered by OA under constant indoor light, fluctuation of solar radiation with ultraviolet irradiances might offset such effects. In this study, when a calcifying and a non-calcifying strain of Emiliania huxleyi were grown at 2 CO2 concentrations (low CO2 [LC]: 395 µatm; high CO2 [HC]: 1000 µatm) under different levels of incident solar radiation in the presence of ultraviolet radiation (UVR), HC and increased levels of solar radiation acted synergistically to enhance the growth in the calcifying strain but not in the non-calcifying strain. HC enhanced the particulate organic carbon (POC) and nitrogen (PON) productions in both strains, and this effect was more obvious at high levels of solar radiation. While HC decreased calcification at low solar radiation levels, it did not cause a significant effect at high levels of solar radiation, implying that a sufficient supply of light energy can offset the impact of OA on the calcifying strain. Our data suggest that increased light exposure, which is predicted to happen with shoaling of the upper mixing layer due to progressive warming, could counteract the impact of OA on coccolithophores distributed within this layer
Production of mirror fermions via and collisions in the littlest Higgs model with T-parity
One of the important features of the littlest Higgs model with T-parity,
called the model, is that it introduces the mirror fermions, which are
the T-parity partners of the standard model fermions. In this paper, we discuss
production of the mirror quark associated with mirror neutrino via
and collisions. We find that, in wide range of the parameter space, the
mirror quark can be copiously produced at the International Linear
Collider and collider experiments. The production rates
of certain signal events, which are related the main two-body decay modes of
the mirror quark, are also calculated.Comment: 19 pages, 11 figure
Study on mechanical properties and microscopic damage mechanism of tight sandstone reservoir under uniaxial compression
Due to the characteristics of low porosity, low permeability and serious anisotropy in tight reservoirs, it is difficult for conventional hydraulic fracturing theory to accurately guide the efficient exploitation of tight reservoirs. It has been shown that the reservoir rock mechanical properties are the key factor impacting the fracturing effect, but the current research on the damage properties of tight reservoir rocks is not comprehensive enough. Therefore, in order to improve the fracturing theory of tight reservoirs, this paper first explores the evolution mechanism of rock fractures through uniaxial compression experiments. Secondly, based on the particle discrete element method, the damage and failure process of tight sandstone under uniaxial compression is simulated from the microscopic scale. The test results show that the rock failure mainly includes tensile failure, shear failure, and tensile-shear failure; Internal micro-fractures will interconnect during rock destruction to form primary fractures through the rock mass, while secondary micro-fractures will also be generated. The numerical simulation results show that when the rock is subjected to tensile-shear failure, with the increase of load, tensile micro-fractures are mainly produced in the specimen, accompanied by a few shear fractures. Under the joint action of shear failure and tensile failure, V-shaped cracks are easily formed in rock. The tensile strength of rock is mainly affected by the microscopic tensile strength, and the cohesive force, modulus, stiffness ratio, friction coefficient and friction angle have significant effects on the compressive strength of rock. Therefore, a reasonable choice of microscopic parameters can realistically simulate the compression-tensile strength ratio of the rock. The research results of this paper can provide the theoretical basis of rock mechanics for the efficient exploitation of tight reservoirs
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