917 research outputs found
Bone in vivo: Surface mapping technique
Bone surface mapping technique is proposed on the bases of two kinds of
uniqueness of bone in vivo, (i) magnitude of the principal moments of inertia,
(ii) the direction cosines of principal axes of inertia relative to inertia
reference frame. We choose the principal axes of inertia as the bone coordinate
system axes. The geographical marks such as the prime meridian of the bone in
vivo are defined and methods such as tomographic reconstruction and boundary
development are employed so that the surface of bone in vivo can be mapped.
Experimental results show that the surface mapping technique can both reflect
the shape and help study the surface changes of bone in vivo. The prospect of
such research into the surface shape and changing laws of organ, tissue or cell
will be promising.Comment: 9 pages, 6 figure
Kinase-independent function of RIP1, critical for mature T-cell survival and proliferation.
The death receptor, Fas, triggers apoptotic death and is essential for maintaining homeostasis in the peripheral lymphoid organs. RIP1 was originally cloned when searching for Fas-binding proteins and was later shown to associate also with the signaling complex of TNFR1. Although Fas exclusively induces apoptosis, TNFR1 primarily activates the pro-survival/pro-inflammatory NF-ΞΊB pathway. Mutations in Fas lead to lymphoproliferative (lpr) diseases, and deletion of TNFR1 results in defective innate immune responses. However, the function of RIP1 in the adult lymphoid system has not been well understood, primarily owing to perinatal lethality in mice lacking the entire RIP1 protein in germ cells. This current study investigated the requirement for RIP1 in the T lineage using viable RIP1 mutant mice containing a conditional and kinase-dead RIP1 allele. Disabling the kinase activity of RIP1 had no obvious impact on the T-cell compartment. However, T-cell-specific deletion of RIP1 led to a severe T-lymphopenic condition, owing to a dramatically reduced mature T-cell pool in the periphery. Interestingly, the immature T-cell compartment in the thymus appeared intact. Further analysis showed that mature RIP1(-/-) T cells were severely defective in antigen receptor-induced proliferative responses. Moreover, the RIP1(-/-) T cells displayed greatly increased death and contained elevated caspase activities, an indication of apoptosis. In total, these results revealed a novel, kinase-independent function of RIP1, which is essential for not only promoting TCR-induced proliferative responses but also in blocking apoptosis in mature T cells
Cognitive Grounding and Its Adaptability to Chinese Noun Studies
Cognitive Grammar is a linguistic theory represented by the symbolic thesis and the usage-based thesis. Cognitive grounding theory is a newly fledged theory in CG. Studies related to grounding have been in their infancy, exhibiting a typological vigor. There have been so far no systematic studies devoted to the grounding system of the Chinese language. Chinese grammar studies applying modern Western linguistic theories have long been the pursuit of scholars from generation to generation. This paper is devoted to introduce grounding theory and then focus on its adaptability to Chinese noun studies. It is concluded that (1) grounding is a cognitive process in which the construal of entities becomes more subjective, and in which a type concept is changed into instances that are singled out by the interlocutors; (2) grounding theory and Chinese noun studies have high adaptability, so Chinese noun studies can be approached from the perspective of Chinese nominal grounding
Improved constructions of permutation and multi-permutation codes correcting a burst of stable deletions
Permutation codes and multi-permutation codes have been widely considered due
to their various applications, especially in flash memory. In this paper, we
consider permutation codes and multi-permutation codes against a burst of
stable deletions. In particular, we propose a construction of permutation codes
correcting a burst stable deletion of length , with redundancy . Compared to the previous known results, our improvement
relies on a different strategy to retrieve the missing symbol on the first row
of the array representation of a permutation. We also generalize our
constructions for multi-permutations and the variable length burst model.
Furthermore, we propose a linear-time encoder with optimal redundancy for
single stable deletion correcting permutation codes.Comment: Accepted for publication in IEEE Trans. Inf. Theor
Metal-insulator transition in transition metal dichalcogenide heterobilayer: accurate treatment of interaction
Transition metal dichalcogenide superlattices provide an exciting new
platform for exploring and understanding a variety of phases of matter. The
moir\'e continuum Hamiltonian, of two-dimensional jellium in a modulating
potential, provides a fundamental model for such systems. Accurate computations
with this model are essential for interpreting experimental observations and
making predictions for future explorations. In this work, we combine two
complementary quantum Monte Carlo (QMC) methods, phaseless auxiliary field
quantum Monte Carlo and fixed-phase diffusion Monte Carlo, to study the ground
state of this Hamiltonian. We observe a metal-insulator transition between a
paramagnetic and a N\'eel ordered state as the moir\'e potential
depth and the interaction strength are varied. We find significant differences
from existing results by Hartree-Fock and exact diagonalization studies. In
addition, we benchmark density-functional theory, and suggest an optimal hybrid
functional which best approximates our QMC results.Comment: 7 pages, 4 figure
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