927 research outputs found
Errata for Stochastic calculus for symmetric Markov processes
This erratum corrects the article arXiv:0806.2044 published in Ann. Probab.
36 (2008) 931--970Comment: Published in at http://dx.doi.org/10.1214/11-AOP684 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Eigenstates of the lattice RS model
For quantum field theories involving interaction between fermion and boson
fields, the bare fermionic (bosonic) annihilation operators cannot annihilate
the vacuum state, and the bare fermionic (bosonic) creation operators cannot
create fermionic (bosonic) one-particle states. The actual bosonic particles
contain fermion field components, and fermionic particles contain boson field
components, while the vacuum state exhibits entanglement between the fermion
and boson fields. We utilize the lattice Rothe-Stamatescu (RS) model to
nonperturbatively and directly demonstrate this field mixing. We provide the
Hamiltonian of the lattice RS model, calculate its correlation functions, and
observe that the correlation functions in the continuum limit recover those of
the original continuous RS model. Furthermore, we derive the equations of
motion for the lattice RS model and compare them to those of the original RS
model. Instead of employing the traditional Fock representation commonly used
in discussions of field mixing, we define a special representation to present
the vacuum state and one-particle states of the lattice RS model. These
eigenstates not only reveal the entanglement between the boson and fermion
fields but also allow us to directly observe the spatial entanglement
structure.Comment: 59 pages, no figure
3-(4-Chlorophenyl)-1-(4-nitrophenyl)benzo[f]quinoline
In the title compound, C25H15ClN2O2, the pyridine ring is inclined at angles of 6.89 (7), 4.24 (9) and 66.98 (4)° with respect to the naphthalene, chlorophenyl and nitrophenyl rings, respectively. The two substituent aromatic rings make a dihedral angle of 71.1 (1)° with one another. C—H⋯π and π–π stacking are present in the crystal structure; the π–π stacking [centroid–centroid distance between the pyridyl rings of adjacent molecules= 3.7838 (11) Å] links the molecules into dimers, while the C—H⋯Cg type π–ring interactons link the molecules into a chain structure along c
A broad-spectrum substrate for the human UDP-glucuronosyltransferases and its use for investigating glucuronidation inhibitors
Strong inhibition of the human UDP-glucuronosyltransferase enzymes (UGTs) may lead to undesirable effects, including hyperbilirubinaemia and drugiherb-drug interactions. Currently, there is no good way to examine the inhibitory effects and specificities of compounds toward all the important human UGTs, side-by-side and under identical conditions. Herein, we report a new, broad-spectrum substrate for human UGTs and its uses in screening and characterizing of UGT inhibitors. Following screening a variety of phenolic compound(s), we have found that methylophiopogonanone A (MOA) can be readily O-glucuronidated by all tested human UGTs, including the typical N-glucuronidating enzymes UGT1A4 and UGT2B10. MOA-O-glucuronidation yielded a single mono-O-glucuronide that was biosynthesized and purified for structural characterization and for constructing an LC-UV based MOA-O-glucuronidation activity assay, which was then used for investigating MOA-O-glucuronidation kinetics in recombinant human UGTs. The derived K-m values were crucial for selecting the most suitable assay conditions for assessing inhibitory potentials and specificity of test compound(s). Furthermore, the inhibitory effects and specificities of four known UGT inhibitors were reinvestigated by using MOA as the substrate for all tested UGTs. Collectively, MOA is a broad-spectrum substrate for the human UGTs, which offers a new and practical tool for assessing inhibitory effects and specificities of UGT inhibitors. (C) 2021 Elsevier B.V. All rights reserved.Peer reviewe
Design of Single-Molecule Multiferroics for Efficient Ultrahigh-Density Nonvolatile Memories
It is known that an isolated single-molecule magnet tends to become super- paramagnetic even at an ultralow temperature of a few Kelvin due to the low spin switching barrier. Herein, single-molecule ferroelectrics/multiferroics is proposed, as the ultimate size limit of memory, such that every molecule can store 1 bit data. The primary strategy is to identify polar molecules that possess bistable states, moderate switching barriers, and polarizations fixed along the vertical direction for high-density perpendicular recording. First- principles computation shows that several selected magnetic metal porphyrin molecules possess buckled structures with switchable vertical polarizations that are robust at ambient conditions. When intercalated within a bilayer of 2D materials such as bilayer MoS2 or CrI3, the magnetization can alter the spin distribution or can be even switched by 180° upon ferroelectric switching, rendering efficient electric writing and magnetic reading. It is found that the upper limit of areal storage density can be enhanced by four orders of magnitude, from the previous super-paramagnetic limit of ≈40 to ≈106 GB in.−2, on the basis of the design of cross-point multiferroic tunneling junction array and multiferroic hard drive
Eliciting the Low-Activity Aldehyde Dehydrogenase Asian Phenotype by an Antisense Mechanism Results in an Aversion to Ethanol
A mutation in the gene encoding for the liver mitochondrial aldehyde dehydrogenase (ALDH2–2), present in some Asian populations, lowers or abolishes the activity of this enzyme and results in elevations in blood acetaldehyde upon ethanol consumption, a phenotype that greatly protects against alcohol abuse and alcoholism. We have determined whether the administration of antisense phosphorothioate oligonucleotides (ASOs) can mimic the low-activity ALDH2–2 Asian phenotype. Rat hepatoma cells incubated for 24 h with an antisense oligonucleotide (ASO-9) showed reductions in ALDH2 mRNA levels of 85% and ALDH2 (half-life of 22 h) activity of 55% equivalent to a >90% inhibition in ALDH2 synthesis. Glutamate dehydrogenase mRNA and activity remained unchanged. Base mismatches in the oligonucleotide rendered ASO-9 virtually inactive, confirming an antisense effect. Administration of ASO-9 (20 mg/kg/day for 4 d) to rats resulted in a 50% reduction in liver ALDH2 mRNA, a 40% inhibition in ALDH2 activity, and a fourfold (P < 0.001) increase in circulating plasma acetaldehyde levels after ethanol (1 g/kg) administration. Administration of ASO-9 to rats by osmotic pumps led to an aversion (−61%, P < 0.02) to ethanol. These studies provide a proof of principle that specific inhibition of gene expression can be used to mimic the protective effects afforded by the ALDH2–2 phenotype
Generating Synergistic Formulaic Alpha Collections via Reinforcement Learning
In the field of quantitative trading, it is common practice to transform raw
historical stock data into indicative signals for the market trend. Such
signals are called alpha factors. Alphas in formula forms are more
interpretable and thus favored by practitioners concerned with risk. In
practice, a set of formulaic alphas is often used together for better modeling
precision, so we need to find synergistic formulaic alpha sets that work well
together. However, most traditional alpha generators mine alphas one by one
separately, overlooking the fact that the alphas would be combined later. In
this paper, we propose a new alpha-mining framework that prioritizes mining a
synergistic set of alphas, i.e., it directly uses the performance of the
downstream combination model to optimize the alpha generator. Our framework
also leverages the strong exploratory capabilities of reinforcement
learning~(RL) to better explore the vast search space of formulaic alphas. The
contribution to the combination models' performance is assigned to be the
return used in the RL process, driving the alpha generator to find better
alphas that improve upon the current set. Experimental evaluations on
real-world stock market data demonstrate both the effectiveness and the
efficiency of our framework for stock trend forecasting. The investment
simulation results show that our framework is able to achieve higher returns
compared to previous approaches.Comment: Accepted by KDD '23, ADS trac
1,2-Bis[5-(4-cyanophenyl)-2-methyl-3-thienyl]-3,3,4,4,5,5-hexafluorocyclopent-1-ene: a photochromic diarylethene compound
The molecules of the title compound, C29H16F6N2S2, a photochromic dithienylethene with 4-cyanophenyl substituents, adopt an antiparallel arrangement that is reponsible for photoactivity. The molecule lies on a twofold rotation axis. The dihedral angle between the nearly planar cyclopentenyl and heteroaryl rings is 142.5 (3)°, and that between the heteroaryl and benzene rings is 22.4 (3)°. The distance between the heteroaryl rings of adjacent molecules is 3.601 (2) Å, indicating a π–π interaction
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