372 research outputs found
Asymptotic pseudodifferential calculus and the rescaled bundle
By following a groupoid approach to pseudodifferential calculus developed by
Van erp and Yuncken, we study the parallel theory on the rescaled bundle and
show that the rescaled bundle gives a geometric characterization to asymptotic
pseudodifferential calculus on spinor bundles by Block and Fox
Rational design of a polyoxometalate intercalated layered double hydroxide: highly efficient catalytic epoxidation of allylic alcohols under mild and solvent-free conditions
Intercalation catalysts, owing to their modular and accessible gallery and unique interlamellar chemical environment, have shown wide application in various catalytic reactions. However, the poor mass transfer between the active components of the intercalated catalysts and organic substrates is one of the challenges that limit their further application. Herein, we have developed a novel heterogeneous catalyst by intercalating the polyoxometalate (POM) of Na9LaW10O36⋅32 H2O (LaW10) into layered double hydroxides (LDHs), which have been covalently modified with ionic liquids (ILs). The intercalation catalyst demonstrates high activity and selectivity for the epoxidation of various allylic alcohols in the presence of H2O2. For example, trans-2-hexen-1-ol undergoes up to 96 % conversion and 99 % epoxide selectivity at 25 °C in 2.5 h. To the best of our knowledge, the Mg3Al−ILs−C8−LaW10 composite material constitutes one of the most efficient heterogeneous catalysts for the epoxidation of allylic alcohols (including the hydrophobic allylic alcohols with long alkyl chains) reported so far
Expanding CRISPR/Cas9 Genome Editing Capacity in Zebrafish Using SaCas9.
The type II CRISPR/Cas9 system has been used widely for genome editing in zebrafish. However, the requirement for the 5'-NGG-3' protospacer-adjacent motif (PAM) of Cas9 from Streptococcus pyogenes (SpCas9) limits its targeting sequences. Here, we report that a Cas9 ortholog from Staphylococcus aureus (SaCas9), and its KKH variant, successfully induced targeted mutagenesis with high frequency in zebrafish. Confirming previous findings, the SpCas9 variant, VQR, can also induce targeted mutations in zebrafish. Bioinformatics analysis of these new Cas targets suggests that the number of available target sites in the zebrafish genome can be greatly expanded. Collectively, the expanded target repertoire of Cas9 in zebrafish should further facilitate the utility of this organism for genetic studies of vertebrate biology
Triadic-OCD: Asynchronous Online Change Detection with Provable Robustness, Optimality, and Convergence
The primary goal of online change detection (OCD) is to promptly identify
changes in the data stream. OCD problem find a wide variety of applications in
diverse areas, e.g., security detection in smart grids and intrusion detection
in communication networks. Prior research usually assumes precise knowledge of
the system parameters. Nevertheless, this presumption often proves unattainable
in practical scenarios due to factors such as estimation errors, system
updates, etc. This paper aims to take the first attempt to develop a
triadic-OCD framework with certifiable robustness, provable optimality, and
guaranteed convergence. In addition, the proposed triadic-OCD algorithm can be
realized in a fully asynchronous distributed manner, easing the necessity of
transmitting the data to a single server. This asynchronous mechanism could
also mitigate the straggler issue that faced by traditional synchronous
algorithm. Moreover, the non-asymptotic convergence property of Triadic-OCD is
theoretically analyzed, and its iteration complexity to achieve an
-optimal point is derived. Extensive experiments have been conducted
to elucidate the effectiveness of the proposed method.Comment: Accepted at ICML202
The evolution of vertebrate tetraspanins: gene loss, retention, and massive positive selection after whole genome duplications
<p>Abstract</p> <p>Background</p> <p>The vertebrate tetraspanin family has many features which make it suitable for preserving the imprint of ancient sequence evolution and amenable for phylogenomic analysis. So we believe that an in-depth analysis of the tetraspanin evolution not only provides more complete understanding of tetraspanin biology, but offers new insights into the influence of the two rounds of whole genome duplication (2R-WGD) at the origin of vertebrates.</p> <p>Results</p> <p>A detailed phylogeny of vertebrate tetraspanins was constructed by using multiple lines of information, including sequence-based phylogenetics, key structural features, intron configuration and genomic synteny. In particular, a total of 38 modern tetraspanin ortholog lineages in bony vertebrates have been identified and subsequently classified into 17 ancestral lineages existing before 2R-WGD. Based on this phylogeny, we found that the ohnolog retention rate of tetraspanins after 2R-WGD was three times as the average (a rate similar to those of transcription factors and protein kinases). This high rate didn't increase the tetrapanin family size, but changed the family composition, possibly by displacing vertebrate-specific gene lineages with the lineages conserved across deuterostomes. We also found that the period from 2R-WGD to recent time is controlled by gene losses. Meanwhile, positive selection has been detected on 80% of the branches right after 2R-WGDs, which declines significantly on both magnitude and extensity on the following speciation branches. Notably, the loss of mammalian RDS2 is accompanied by strong positive selection on mammalian ROM1, possibly due to gene loss-induced compensatory evolution.</p> <p>Conclusions</p> <p>First, different from transcription factors and kinases, high duplicate retention rate after 2R-WGD didn't increase the tetraspanin family size but just reshaped the family composition. Second, the evolution of tetraspanins right after 2R-WGD had been impacted by a massive wave of gene loss and positive selection on coding sequences. Third, the lingering effect of 2R-WGD on tetraspanin gene loss and positive selection might last for 300-400 million years.</p
The role of the peripheral system dysfunction in the pathogenesis of sepsis-associated encephalopathy
Sepsis is a condition that greatly impacts the brain, leading to neurological dysfunction and heightened mortality rates, making it one of the primary organs affected. Injury to the central nervous system can be attributed to dysfunction of various organs throughout the entire body and imbalances within the peripheral immune system. Furthermore, central nervous system injury can create a vicious circle with infection-induced peripheral immune disorders. We collate the pathogenesis of septic encephalopathy, which involves microglial activation, programmed cell death, mitochondrial dysfunction, endoplasmic reticulum stress, neurotransmitter imbalance, and blood–brain barrier disruption. We also spotlight the effects of intestinal flora and its metabolites, enterocyte-derived exosomes, cholinergic anti-inflammatory pathway, peripheral T cells and their cytokines on septic encephalopathy
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