838 research outputs found
Hypothesis testing for homogenous of nodes in -models
The -model has been extensively utilized to model degree heterogeneity
in networks, wherein each node is assigned a unique parameter. In this article,
we consider the hypothesis testing problem that two nodes and of a
-model have the same node parameter. We prove that the null distribution
of the proposed statistic converges in distribution to the standard normal
distribution. Further, we investigate the homogeneous test for -model by
combining individual -values to aggregate small effects of multiple tests.
Both simulation studies and real-world data examples indicate that the proposed
method works well
Stereoselective Phosphine-Catalyzed Synthesis of Highly Functionalized Diquinanes
Two rings to rule them all: A versatile method has been developed for the room‐temperature synthesis of diquinanes from acyclic precursors, thereby generating two rings, three stereocenters, and a double bond with high selectivity. The products of the double cyclization can be derivatized with excellent diastereoselection into an array of highly functionalized compounds.
[reaction image]
In 2003, Tomika and co‐workers reported an intriguing PnBu3‐catalyzed diastereoselective cyclization of certain yne‐diones to form bicyclic furanones with two new stereocenters (Figure 1).1 They proposed that conjugate addition of the phosphine to the alkyne is followed by tautomerization, which furnishes zwitterionic enolate A. Next, an intramolecular aldol reaction provides B, and then a second conjugate addition generates bicycle C (the conversion of A into C by a concerted cycloaddition may also be considered). Tautomerization and then elimination of the phosphine affords the bicyclic furanone. The investigation by Tomita et al. focused mainly on symmetrical substrates (R1=-C≡CR), although they did report reactions of two unsymmetrical yne‐diones which cyclized in relatively modest yield (41–50 %)
Nickel-Catalyzed Enantioselective Cross-Couplings of Racemic Secondary Electrophiles That Bear an Oxygen Leaving Group
To date, effective nickel-catalyzed enantioselective cross-couplings of alkyl electrophiles that bear oxygen leaving groups have been limited to reactions of allylic alcohol derivatives with Grignard reagents. In this Communication, we establish that, in the presence of a nickel/pybox catalyst, a variety of racemic propargylic carbonates are suitable partners for asymmetric couplings with organozinc reagents. The method is compatible with an array of functional groups and utilizes commercially available catalyst components. The development of a versatile nickel-catalyzed enantioselective cross-coupling process for electrophiles that bear a leaving group other than a halide adds a significant new dimension to the scope of these reactions
A 12-Lead ECG Database to Identify Origins of Idiopathic Ventricular Arrhythmia Containing 334 Patients
Cardiac catheter ablation has shown the effectiveness of treating the idiopathic premature ventricular complex and ventricular tachycardia. As the most important prerequisite for successful therapy, criteria based on analysis of 12-lead ECGs are employed to reliably speculate the locations of idiopathic ventricular arrhythmia before a subsequent catheter ablation procedure. Among these possible locations, right ventricular outflow tract and left outflow tract are the major ones. We created a new 12-lead ECG database under the auspices of Chapman University and Ningbo First Hospital of Zhejiang University that aims to provide high quality data enabling detection of the distinctions between idiopathic ventricular arrhythmia from right ventricular outflow tract to left ventricular outflow tract. The dataset contains 334 subjects who successfully underwent a catheter ablation procedure that validated the accurate origins of idiopathic ventricular arrhythmia
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