3,726 research outputs found
Production of α1,3-galactosyltransferase-deficient pigs
The enzyme α1,3-galactosyltransferase (α1,3GT or GGTA1) synthesizes α1,3galactose (α1,3Gal) epitopes (Galα1,3Galβ1,4GlcNAc-R), which are the major xenoantigens causing hyperacute rejection in pig-to-human xenotransplantation. Complete removal of α1,3Gal from pig organs is the critical step toward the success of xenotransplantation. We reported earlier the targeted disruption of one allele of the α1,3GT gene in cloned pigs. A selection procedure based on a bacteria[toxin was used to select for cells in which the second allele of the gene was knocked out. Sequencing analysis demonstrated that knockout of the second allele of the α1,3GT gene was caused by a T-to-G single point mutation at the second base of exon 9, which resulted in inactivation of the α1,3GT protein. Four healthy α1,3GT double-knockout female piglets were produced by three consecutive rounds of cloning. The piglets carrying a point mutation in the α1,3GT gene hold significant value, as they would allow production of α1,3Gal-deficient pigs free of antibiotic-resistance genes and thus have the potential to make a safer product for human use
Recent advances in carbon-based nanomaterials for multivalent-ion hybrid capacitors: a review
Hybrid capacitors are emerging because of their ability to store large amounts of energy, cycle through charges quickly, and maintain stability even in harsh environments or at extreme temperatures. Hybrid capacitors with monovalent cations such as Li+, Na+, and K+ have been extensively studied. However, the flammable nature of organic electrolytes and the reactive alkali metallic electrodes have raised safety concerns. This has prompted the development of novel aqueous multivalent cation storage systems, which can provide several benefits, including high capacity and energy density, rapid charge transfer, and low cost. With these advantages and the energy storage properties, multivalent cations such as Zn2+, Mg2+, Ca2+, and Al3+ have been applied to multivalent-ion hybrid capacitors (MIHCs), and the latest developments and design ideas for these have been recently reviewed. However, an overview from the perspective of materials with unique advantages and experimental designs remains limited. Carbon-based nanomaterials are leading candidates for next-generation energy storage devices due to their outstanding properties in MIHCs. The use of carbon-based nanomaterials is attractive because these materials are inexpensive, scalable, safe, and non-toxic. They are also bioactive at the anode interface, allowing them to promote electrochemical reactions with redox species that would otherwise not take place. This paper reviews recent advances in MIHCs and related carbon-based materials and discusses the utilization of carbon materials in MIHCs and ideas for material design, electrochemical behavior, energy storage mechanisms, electrode design, and future research prospects. Based on the integration of related challenges and development, we aim to provide insights and commercialization reference for laboratory research. For the first time, combined with global intellectual property analysis, this paper summarizes the current main research institutions and enterprises of various hybrid capacitors, and provides important technical competition information and development trends for researchers and practitioners in the field of energy storage. Simultaneously, we provide a perspective for the development of MIHCs, a description of the existing research, and guidelines for the design, production, commercialization, and advancement of unique high-performance electrochemical energy storage devices
Acute rejection is associated with antibodies to non-Gal antigens in baboons using Gal-knockout pig kidneys
We transplanted kidneys from α1,3-galactosyltransferase knockout (GalT-KO) pigs into six baboons using two different immunosuppressive regimens, but most of the baboons died from severe acute humoral xenograft rejection. Circulating induced antibodies to non-Gal antigens were markedly elevated at rejection, which mediated strong complement-dependent cytotoxicity against GalT-KO porcine target cells. These data suggest that antibodies to non-Gal antigens will present an additional barrier to transplantation of organs from GalT-KO pigs to humans. © 2005 Nature Publishing Group
Generalized Gauge for Multi-scale Inhomogeneous Media
Keynote SpeechThe vector potential A has no direct physical meaning in classical electromagnetics.
However, it manifests itself in quantum physics in terms of the Aharonov-Bohm effect. The vector
potential A is similar to momentum. By itself, it is hard to detect classically, but its time variation
generates a force in terms of electric field. Hence, the E field is of the form
....
BCAA catabolism in brown fat controls energy homeostasis through SLC25A44.
Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health
Nonmonotone Barzilai-Borwein Gradient Algorithm for -Regularized Nonsmooth Minimization in Compressive Sensing
This paper is devoted to minimizing the sum of a smooth function and a
nonsmooth -regularized term. This problem as a special cases includes
the -regularized convex minimization problem in signal processing,
compressive sensing, machine learning, data mining, etc. However, the
non-differentiability of the -norm causes more challenging especially
in large problems encountered in many practical applications. This paper
proposes, analyzes, and tests a Barzilai-Borwein gradient algorithm. At each
iteration, the generated search direction enjoys descent property and can be
easily derived by minimizing a local approximal quadratic model and
simultaneously taking the favorable structure of the -norm. Moreover, a
nonmonotone line search technique is incorporated to find a suitable stepsize
along this direction. The algorithm is easily performed, where the values of
the objective function and the gradient of the smooth term are required at
per-iteration. Under some conditions, the proposed algorithm is shown to be
globally convergent. The limited experiments by using some nonconvex
unconstrained problems from CUTEr library with additive -regularization
illustrate that the proposed algorithm performs quite well. Extensive
experiments for -regularized least squares problems in compressive
sensing verify that our algorithm compares favorably with several
state-of-the-art algorithms which are specifically designed in recent years.Comment: 20 page
The DISC1 Pathway Modulates Expression of Neurodevelopmental, Synaptogenic and Sensory Perception Genes
Genetic and biological evidence supports a role for DISC1 across a spectrum of major mental illnesses, including schizophrenia and bipolar disorder. There is evidence for genetic interplay between variants in DISC1 and in biologically interacting loci in psychiatric illness. DISC1 also associates with normal variance in behavioral and brain imaging phenotypes.Here, we analyze public domain datasets and demonstrate correlations between variants in the DISC1 pathway genes and levels of gene expression. Genetic variants of DISC1, NDE1, PDE4B and PDE4D regulate the expression of cytoskeletal, synaptogenic, neurodevelopmental and sensory perception proteins. Interestingly, these regulated genes include existing targets for drug development in depression and psychosis.Our systematic analysis provides further evidence for the relevance of the DISC1 pathway to major mental illness, identifies additional potential targets for therapeutic intervention and establishes a general strategy to mine public datasets for insights into disease pathways
Constraints on Nucleon Decay via "Invisible" Modes from the Sudbury Neutrino Observatory
Data from the Sudbury Neutrino Observatory have been used to constrain the
lifetime for nucleon decay to ``invisible'' modes, such as n -> 3 nu. The
analysis was based on a search for gamma-rays from the de-excitation of the
residual nucleus that would result from the disappearance of either a proton or
neutron from O16. A limit of tau_inv > 2 x 10^{29} years is obtained at 90%
confidence for either neutron or proton decay modes. This is about an order of
magnitude more stringent than previous constraints on invisible proton decay
modes and 400 times more stringent than similar neutron modes.Comment: Update includes missing efficiency factor (limits change by factor of
2) Submitted to Physical Review Letter
Local Difference Measures between Complex Networks for Dynamical System Model Evaluation
Acknowledgments We thank Reik V. Donner for inspiring suggestions that initialized the work presented herein. Jan H. Feldhoff is credited for providing us with the STARS simulation data and for his contributions to fruitful discussions. Comments by the anonymous reviewers are gratefully acknowledged as they led to substantial improvements of the manuscript.Peer reviewedPublisher PD
Microwave studies of the fractional Josephson effect in HgTe-based Josephson junctions
The rise of topological phases of matter is strongly connected to their
potential to host Majorana bound states, a powerful ingredient in the search
for a robust, topologically protected, quantum information processing. In order
to produce such states, a method of choice is to induce superconductivity in
topological insulators. The engineering of the interplay between
superconductivity and the electronic properties of a topological insulator is a
challenging task and it is consequently very important to understand the
physics of simple superconducting devices such as Josephson junctions, in which
new topological properties are expected to emerge. In this article, we review
recent experiments investigating topological superconductivity in topological
insulators, using microwave excitation and detection techniques. More
precisely, we have fabricated and studied topological Josephson junctions made
of HgTe weak links in contact with two Al or Nb contacts. In such devices, we
have observed two signatures of the fractional Josephson effect, which is
expected to emerge from topologically-protected gapless Andreev bound states.
We first recall the theoretical background on topological Josephson junctions,
then move to the experimental observations. Then, we assess the topological
origin of the observed features and conclude with an outlook towards more
advanced microwave spectroscopy experiments, currently under development.Comment: Lectures given at the San Sebastian Topological Matter School 2017,
published in "Topological Matter. Springer Series in Solid-State Sciences,
vol 190. Springer
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