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2021 ◽  
Author(s):  
Moetasim Ashfaq ◽  
Shahid Mehmood ◽  
Sarah Kapnick ◽  
Subimal Ghosh ◽  
Muhammad Adnan Abid ◽  
...  

Abstract A robust understanding of the sub-seasonal cold season (November–March) precipitation variability over the High Mountains of Asia (HMA) is currently lacking. Here, we identify dynamic and thermodynamic pathways through which natural modes of climate variability establish their teleconnections over the HMA. First, we identify evaporative sources that contribute to the cold season precipitation over the HMA and surroundings areas. The predominant moisture contribution comes from the mid-latitude regions including Mediterranean/Caspian Seas and Mediterranean land. Second, we establish that several tropical and extratropical forcing display a sub-seasonally fluctuating influence on the cold season precipitation distribution over the region, and given that many of them varyingly interact with each other, their impacts cannot be explained exclusively or at seasonal timescales. Lastly, a single set of evaporative sources cannot always be identified as the only determinant in propagating a remote teleconnection, because nature of moisture anomalies and its sources depend on the pattern of sub-seasonally varying dynamical forcing in the atmosphere.


Author(s):  
Afshin Anssari-Benam ◽  
Andrea Bucchi ◽  
Cornelius O. Horgan ◽  
Giuseppe Saccomandi

ABSTRACT The choice of an appropriate strain energy function W is key to accurate modeling and computational finite element analysis of the mechanical behavior of unfilled non-crystalizing rubberlike materials. Despite the existing variety of models, finding a suitable model that can capture many deformation modes of a rubber specimen with a single set of parameter values and satisfy the a priori mathematical and structural requirements remains a formidable task. Previous work proposed a new generalized neo-Hookean W (I1) function, showing a promising fitting capability and enjoying a structural basis. We now use two extended forms of that model that include an I1 term adjunct, W (I1, I2), for application to various boundary value problems commonly encountered in rubber mechanics applications. Specifically, two functional forms of the I2 invariant are considered: a linear function and a logarithmic function. The boundary value problems of interest include the in-plane uniaxial, equi-biaxial, and pure shear deformations and simple shear, inflation, and nonhomogeneous deformations such as torsion. By simultaneous fitting of each model to various deformation modes of rubber specimens, it is demonstrated that a single set of model parameter values favorably captures the mechanical response for all the considered deformations of each specimen. It is further shown that the model with a logarithmic I2 function provides better fits than the linear function. Given the functional simplicity of the considered W (I1, I2) models, the low number of model parameters (three in total), the structurally motivated bases of the models, and their capability to capture the mechanical response for various deformations of rubber specimens, the considered models are recommended as a powerful tool for practical applications and analysis of rubber elasticity.


Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6395
Author(s):  
Shamsher Ali ◽  
Eric Hénon ◽  
Ritchy Leroy ◽  
Georges Massiot

Vindoline and catharanthine are the major alkaloids of Catharanthus roseus and are extracted in large quantities to prepare the pharmaceutically important Vinca type alkaloids vincaleukoblastine, vincristine and navelbine. The higher yield of vindoline relative to catharanthine makes it an attractive substrate for developing new chemistry and adding value to the plant. In this context, we have reacted vindoline with a selection of electrophiles among which benzoquinone. Conditions were developed to optimize the synthesis of a mono-adduct, of five bis-adducts, and of tri-adducts and tetra-adducts, several of these adducts being mixtures of conformational isomers. Copper(II) was added to the reactions to promote reoxidation of the intermediate hydroquinones and simplify the reaction products. The structures were solved by spectroscopic means and by symmetry considerations. Among the bis-isomers, the 2,3-diadduct consists of three unseparable species, two major ones with an axis of symmetry, thus giving a single set of signals and existing as two different species with indistinguishable NMR spectra. The third and minor isomer has no symmetry and therefore exhibits nonequivalence in the signals of the two vindoline moieties. These isomers are designated as syn (minor) and anti (major) and there exists a high energy barrier between them making their interconversion difficult. DFT calculations on simplified model compounds demonstrate that the syn-anti interconversion is not possible at room temperature on the NMR chemical shift time scale. These molecules are not rigid and calculations showed a back-and-forth conrotatory motion of the two vindolines. This “windshield wiper” effect is responsible for the observation of exchange correlations in the NOESY spectra. The same phenomenon is observed with the higher molecular weight adducts, which are also mixtures of rotational isomers. The same lack of rotations between syn and anti isomers is responsible for the formation of four tri-adducts and of seven tetra-adducts. On a biological standpoint, the mono adduct displayed anti-inflammatory properties at the 5 μM level while the di-adducts and tri-adducts showed moderate cytotoxicity against Au565, and HeLa cancer cell lines.


2021 ◽  
Author(s):  
Riovie Ramos ◽  
Allegra LeGrande ◽  
Michael Griffiths ◽  
Gregory Elsaesser ◽  
Daniel Litchmore ◽  
...  

Cloud and convective parameterizations strongly influence uncertainties in equilibrium climate sensitivity (ECS). We provide a proof-of-concept study to constrain these parameterizations in a perturbed parameter ensemble of atmosphere-only simulations by evaluating model biases in the present-day runs using multiple satellite climatologies and by comparing simulated δ18O of precipitation (δ18Op), known to be sensitive to parameterization schemes, with a global database of speleothem δ18O records covering the Last Glacial Maximum (LGM), mid-Holocene (MH) and pre-industrial (PI) periods. Relative to modern, paleoclimate simulations show greater sensitivity to parameter changes, allowing for an evaluation of uncertainties over a broader range of climate forcing and the identification of parts of the world that are parameter sensitive. Certain simulations reproduced LGM and MH δ18Op anomalies relative to the PI better than the default parameterization. Not a single set of parameterizations worked well in all climate states, thus improving simulations requires determining all plausible parameter combinations.


2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Leonardo Andrade Ribeiro ◽  
Felipe Ferreira Borges ◽  
Diego Oliveira

We consider the problem of efficiently answering set similarity joins on multi-attribute data. Traditional set similarity join algorithms assume string data represented by a single set and, thus, miss the opportunity to exploit predicates over multiple attributes to reduce the number of similarity computations. In this article, we present a framework to enhance existing algorithms with additional filters for dealing with multi-attribute data. We then instantiate this framework with a lightweight filtering technique based on a simple, yet effective data structure, for which exact and probabilistic implementations are evaluated. In this context, we devise a cost model to identify the best attribute ordering to reduce processing time. Moreover, alternative approaches are also investigated and a new algorithm combining key ideas from previous work is introduced. Finally, we present a thorough experimental evaluation, which demonstrates that our main proposal is efficient and significantly outperforms competing algorithms.


2021 ◽  
Vol 107 ◽  
pp. 102826
Author(s):  
Jesper Larsson Träff ◽  
Sascha Hunold ◽  
Guillaume Mercier ◽  
Daniel J. Holmes

2021 ◽  
Vol 133 (10) ◽  
Author(s):  
Martin Lara

AbstractBrouwer’s solution to the artificial satellite problem is revisited. We show that the complete Hamiltonian reduction is rather achieved in the plain Poincaré’s style, through a single canonical transformation, than using a sequence of partial reductions based on von Zeipel’s alternative for dealing with perturbed degenerate Hamiltonian systems. Beyond the theoretical interest of the new approach as regards the complete reduction of perturbed Keplerian motion, we also show that a solution based on a single set of corrections may yield computational benefits in the implementation of an analytic orbit propagator.


10.51868/7 ◽  
2021 ◽  
pp. 117-131
Author(s):  
Felix Chang ◽  
Erin McCabe ◽  
Zhaowei Ren ◽  
Joshua Beckelhimer ◽  
James Lee

Utilizing antitrust decisions extracted from the Caselaw Access Project, we aggregate—or embed—layers of topic modeling into a single set of visualizations. Aggregated models can provide new perspectives on how courts tackle thorny doctrinal questions, such as the measure of market power and the balance between antitrust and regulation. Our central contribution is the improvement of natural language processing to provide greater context for key terms. Our secondary contribution is a new suite of tools to assess the weighty policy arguments that currently dominate antitrust.


Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 552
Author(s):  
Shin-Liang Chen ◽  
Huan-Yu Ku ◽  
Wenbin Zhou ◽  
Jordi Tura ◽  
Yueh-Nan Chen

Given a Bell inequality, if its maximal quantum violation can be achieved only by a single set of measurements for each party or a single quantum state, up to local unitaries, one refers to such a phenomenon as self-testing. For instance, the maximal quantum violation of the Clauser-Horne-Shimony-Holt inequality certifies that the underlying state contains the two-qubit maximally entangled state and the measurements of one party contains a pair of anti-commuting qubit observables. As a consequence, the other party automatically verifies the set of states remotely steered, namely the "assemblage", is in the eigenstates of a pair of anti-commuting observables. It is natural to ask if the quantum violation of the Bell inequality is not maximally achieved, or if one does not care about self-testing the state or measurements, are we capable of estimating how close the underlying assemblage is to the reference one? In this work, we provide a systematic device-independent estimation by proposing a framework called "robust self-testing of steerable quantum assemblages". In particular, we consider assemblages violating several paradigmatic Bell inequalities and obtain the robust self-testing statement for each scenario. Our result is device-independent (DI), i.e., no assumption is made on the shared state and the measurement devices involved. Our work thus not only paves a way for exploring the connection between the boundary of quantum set of correlations and steerable assemblages, but also provides a useful tool in the areas of DI quantum certification. As two explicit applications, we show 1) that it can be used for an alternative proof of the protocol of DI certification of all entangled two-qubit states proposed by Bowles et al., and 2) that it can be used to verify all non-entanglement-breaking qubit channels with fewer assumptions compared with the work of Rosset et al.


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