2,782 research outputs found
Reactions of C({\it a}) with selected saturated alkanes: A temperature dependence study
We present a temperature dependence study on the gas phase reactions of the
C({\it a}) radical with a selected series of saturated alkanes
(CH, CH, n-CH, i-CH, and n-CH) by
means of pulsed laser photolysis/laser-induced fluorescence technique. The
bimolecular rate constants for these reactions were obtained between 298 and
673 K. A pronounced negative temperature effect was observed for n-CH,
i-CH, and n-CH and interpreted in terms of steric hindrance
of the more reactive secondary or tertiary C-H bonds by less reactive CH
groups. Detailed analysis of our experimental results reveals quantitatively
the temperature dependence of reactivities for the primary, secondary, and
tertiary C-H bonds in these saturated alkanes and further lends support to a
mechanism of hydrogen abstraction.Comment: 26 pages, 8 figures, 1 table, 30 references; accepted to JC
MORE: Measurement and Correlation Based Variational Quantum Circuit for Multi-classification
Quantum computing has shown considerable promise for compute-intensive tasks
in recent years. For instance, classification tasks based on quantum neural
networks (QNN) have garnered significant interest from researchers and have
been evaluated in various scenarios. However, the majority of quantum
classifiers are currently limited to binary classification tasks due to either
constrained quantum computing resources or the need for intensive classical
post-processing. In this paper, we propose an efficient quantum
multi-classifier called MORE, which stands for measurement and correlation
based variational quantum multi-classifier. MORE adopts the same variational
ansatz as binary classifiers while performing multi-classification by fully
utilizing the quantum information of a single readout qubit. To extract the
complete information from the readout qubit, we select three observables that
form the basis of a two-dimensional Hilbert space. We then use the quantum
state tomography technique to reconstruct the readout state from the
measurement results. Afterward, we explore the correlation between classes to
determine the quantum labels for classes using the variational quantum
clustering approach. Next, quantum label-based supervised learning is performed
to identify the mapping between the input data and their corresponding quantum
labels. Finally, the predicted label is determined by its closest quantum label
when using the classifier. We implement this approach using the Qiskit Python
library and evaluate it through extensive experiments on both noise-free and
noisy quantum systems. Our evaluation results demonstrate that MORE, despite
using a simple ansatz and limited quantum resources, achieves advanced
performance.Comment: IEEE International Conference on Quantum Computing and Engineering
(QCE23
The Lower Bounds for Eigenvalues of Elliptic Operators --By Nonconforming Finite Element Methods
The aim of the paper is to introduce a new systematic method that can produce
lower bounds for eigenvalues. The main idea is to use nonconforming finite
element methods. The general conclusion herein is that if local approximation
properties of nonconforming finite element spaces are better than global
continuity properties of , corresponding methods will produce lower bounds
for eigenvalues. More precisely, under three conditions on continuity and
approximation properties of nonconforming finite element spaces we first show
abstract error estimates of approximate eigenvalues and eigenfunctions.
Subsequently, we propose one more condition and prove that it is sufficient to
guarantee nonconforming finite element methods to produce lower bounds for
eigenvalues of symmetric elliptic operators. As one application, we show that
this condition hold for most nonconforming elements in literature. As another
important application, this condition provides a guidance to modify known
nonconforming elements in literature and to propose new nonconforming elements.
In fact, we enrich locally the Crouzeix-Raviart element such that the new
element satisfies the condition; we propose a new nonconforming element for
second order elliptic operators and prove that it will yield lower bounds for
eigenvalues. Finally, we prove the saturation condition for most nonconforming
elements.Comment: 24 page
Differential Actions of Ethanol and Trichloroethanol at Sites in the M3 and M4 Domains of the NMDA Receptor GluN2A (NR2A) Subunit
Background and purpose:β Alcohol produces its behavioural effects in part due to inhibition of N-methyl-d-aspartate (NMDA) receptors in the CNS. Previous studies have identified amino acid residues in membrane-associated domains 3 (M3) and 4 (M4) of the NMDA receptor that influence ethanol sensitivity. In addition, in other alcohol-sensitive ion channels, sedative-hypnotic agents have in some cases been shown to act at sites distinct from the sites of ethanol action. In this study, we compared the influence of mutations at these sites on sensitivity to ethanol and trichloroethanol, a sedative-hypnotic agent that is a structural analogue of ethanol.
Experimental approach:β We constructed panels of mutants at ethanol-sensitive positions in the GluN2A (NR2A) NMDA receptor subunit and transiently expressed these mutants in human embryonic kidney 293 cells. We used whole-cell patch-clamp recording to assess the actions of ethanol and trichloroethanol in these mutant NMDA receptors.
Key results:β Ethanol sensitivity of mutants at GluN2A(Ala825) was not correlated with any physicochemical measures tested. Trichloroethanol sensitivity was altered in two of three ethanol-insensitive mutant GluN2A subunits: GluN2A(Phe637Trp) in M3 and GluN2A(Ala825Trp) in M4, but not GluN2A(Met823Trp). Trichloroethanol sensitivity decreased with increasing molecular volume at Phe637 or increasing hydrophobicity at Ala825 and was correlated with ethanol sensitivity at both sites.
Conclusions and implications:β Evidence obtained to date is consistent with a role of GluN2A(Ala825) as a modulatory site for ethanol and trichloroethanol sensitivity, but not as a binding site. Trichloroethanol appears to inhibit the NMDA receptor in a manner similar, but not identical to, that of ethanol
Translation on-the-fly add-on based on existing translation files and machine-translation
A new method for translating webpage on-the-fly is disclosed. This method use a browser add-on to auto localize the newly developed webpage or web application using existing translation files or machine-translation, so that web UI developer can detect & fix potential layout issues (including bad layout and truncation) during development time
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