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We identify the previously unknown mechanism whereby rocksalt Ta x N can be continuously tuned from conducting to insulating through changes in stoichiometry. Experimental measurements on thin films, combined with electronic structure calculations on a host of native defects, show that the tunability arises from changes in the free electron concentration as a result of localization at Ta vacancies (V Ta ). The observed enhanced resistivity, transition from electron to hole conduction at xϳ0.6, and diminished mid-IR reflectance are consistent with the dominance of the V Ta defect in nitrogen-rich material.

We report on the growth, fabrication, and device characterization of NbN internally shunted Josephson junctions with a TaNx barrier. The resistivity of TaNx films could be varied from a few hundred micro-ohms to a few hundred milliohms by increasing the N2 pressure during reactive sputtering. The temperature dependence of IcRn of the junctions with ∼13 mΩ cm barrier resistivity was measured for various barrier thicknesses. The coherence length of the barrier was determined to be 5 nm. By adjusting the barrier thickness, IcRn values >500 μV were observed up to 8.3 K, with Ic and Rn of magnitudes that are suitable for single-flux-quantum digital circuits.

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Background. Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular mortality and morbidity. Several studies have reported that it affects the left ventricle; however, large randomized controlled trials are lacking. The current study aimed to summarize the association between OSAS and left ventricular (LV) structure and function. Methods. Electronic databases (PubMed, Embase, and Cochrane) and references were searched for articles published until March 2018. A systematic review and metaanalysis were performed to assess LV structure and function in OSAS patients based on echocardiography.

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