Assessing the potential of perfect screw dislocations in SiC for solid-state quantum technologies

Although point defects in solids are one of the most promising physical systems to build functioning qubits, it remains challenging to position them in a deterministic array and to integrate them into large networks. By means of advanced ab initio calculations we show that undissociated screw dislocations in cubic 3C-SiC, and their associated strain fields, could be used to create a deterministic pattern of relevant point defects. Specifically, we present a detailed analysis of the formation energies and electronic structure of the divacancy in 3C-SiC when located in the vicinity of this type of dislocations. Our results show that the divacancy is strongly attracted towards specific and equivalent sites inside the core of the screw dislocations, and would form a one-dimensional arrays along them. Furthermore, we show that the same strain that attracts the divacancy allows the modulation of the position of its electronic states and of its charge transition levels. In the case of the neutral divacancy, we find that these modulations result in the loss of its potential as a qubit. However, these same modulations could transform defects with no potential as qubits when located in bulk, into promising defects when located inside the core of the screw dislocations. Since dislocations are still mostly perceived as harmful defects, our findings represent a technological leap as they show that dislocations can be used as active building blocks in future defect-based quantum computers

Rethinking Warning: Intelligence, Novel Events, and the COVID-19 Pandemic

17 USC 105 interim-entered record; under temporary embargo.U.S. Government affiliation is unstated in article text

Erste Beobachtungen mit dem abstimmbaren Infrarot-Heterodynsystem THIS

Gegenstand der vorliegenden Arbeit ist die technische Weiterentwicklung des durchstimmbaren Infrarot-Heterodynsystems THIS (Tuneable Heterodyne Infrared Spectrometer) sowie die Planung, Vorbereitung und Durchführung diverser Beobachtungseinsätze des Instruments an unterschiedlichen Teleskopen. Auf technischer Seite konnte der sehr erfolgreiche Einsatz von Quanten- Kaskadenlasern als Lokaloszillatoren, die Empfindlichkeit des Systems erstmals auf das Niveau von CO2-Laser gepumpten Instrumenten bringen. Frequenzstabilität und radiometrisches Verhalten des Instruments konnten für Beobachtungszeiträume von einigen Stunden nachgewiesen werden.Weiterhin wurde ein in den Empfänger integriertes, optisches Guide-System für den Einsatz an Teleskopen entwickelt und aufgebaut. Die neu entwickelte Optik macht THIS durch die Verwendung einer integrierten optischen Kamera sowie eines Scannerspiegels zur Auswahl von Beobachtungspositionen am Himmel weitgehend unabhängig vom Teleskoptyp und damit vielseitig einsetzbar. Die technischen Neuerungen und die mechanische Stabilität des neuen Aufbaus wurden u. a. während Messperioden am Observatorium Hoher List bei Daun/Eifel sowie am McMath-Pierce Solar Telescope auf dem Kitt Peak nahe Tucson/Arizona erstmalig außerhalb des Labors genutzt und getestet. Es konnten Molekül-Absorptionen aus Sonnenflecken aufgenommen und aus den vollständig aufgelösten Linienprofilen die Anregungstemperaturen des Materials bestimmt werden. In diesem Zusammenhang wurde eine theoretische Analyse der Kalibration von am Teleskop gewonnenen Spektren durchgeführt und auf die gemessenen Daten angewandt. Weiterhin konnten erstmals mit THIS nicht-terrestrische Signale in Form von schwachen, nicht-thermischen CO2- Emissionen aus der von der Sonne beleuchteten Venus- und Mars-Atmosphäre detektiert werden. Die exzellente Empfindlichkeit des Instruments konnte zusätzlich durch die Beobachtung von stratosphärischem Ozon gegen einen Stern als Hintergrundquelle demonstriert werden. Weitere Beobachtungseinsätze von THIS sind in Zusammenarbeit mit dem GSFC der NASA in Vorbereitung. Beobachtungsziele sind interessante molekulare Absorptions- und Emissionslinien in Planetenatmosphären, die nicht mit Gaslaser-Instrumenten beobachtbar sind. Dazu zählt die hochaufgelöste Vermessung der bereits erwähnten CO2-Laseremissionen oder die Bestimmung von Häufigkeiten von leichten Kohlenwasserstoffen wie C2H4 oder C2H6

A Methodology for Three-Dimensional Quantification of Anterior Tooth Width

The use of cone-beam computed tomography (CBCT) technology has been shown to be more accurate in measuring individual incisor tooth widths than the use of wax exemplars. There were fewer differences by investigators using CBCT than others using an F-test in a mixed model of the measurement differences of investigators, wax type, and which tooth was measured. In addition, the frequency of outliers was less in the CBCT method (a total of 5) as compared to the two-dimensional measurements in ether Aluwax (a total of 8) or Coprwax (a total of 12). Both results indicate that CBCT measurements accounted more precisely for tooth width and level of eruption

Quantification of the Individual Characteristics of the Human Dentition

The considerations for admissibility suggested by the Daubert trilogy challenge forensic experts to provide scientific support for opinion testimony. The defense bar has questioned the reliability of bitemark analysis. Under an award from the U. S. Department of Justice, via the Midwest Forensic Resource Center, a two-year feasibility study was undertaken to quantify six dental characteristics. Using two computer programs, the exemplars of 419 volunteers were digitally scanned, characteristics were measured, and frequency was calculated. The study demonstrates that there were outliers or rare dental characteristics in measurements. An analysis of the intra-observer and inter-observer consistency demonstrated a high degree of agreement. Expansion of the sample size through collaboration with other academic researchers will be necessary to be able to quantify the occurrence of these characteristics in the general population. The automated software application, Tom\u27s Toolbox, developed specifically for this research project, could also provide a template for precisely quantifying other pattern evidence

Plio-Pleistozängrenze und Günzeiszeit in Nordwestdeutschland

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Evaluating Return On Investment For Software Process Improvement Projects

This article presents a simple approach that will allow decision-makers to evaluate the return on investment of software process improvement prior to launching such an effort. Obviously, it will be easy to tell ten years up the road whether the right decision was made. But a CEO, or CIO contemplating laying out six, or seven figures for the additional personnel and resources to conduct SPI is not in a position to make that call and the wise ones will not be led into it by blind faith. The problem is assessing the risks and returns of such a project in terms and perspective that a non-technical decision-maker can understand. We believe our instrument serves that purpose

Assessing the potential of perfect screw dislocations in SiC for solid-state quantum technologies

editorial reviewedAlthough point defects in solids can be used as qubits, it remains challenging to position them in a deterministic array. By means of advanced ab initio calculations we show that perfect screw dislocations in 3C-SiC could be used to overcome this limitation. In addition, we show that such dislocations can change the spin configuration of a point defect located inside its core, without changing the localized nature of its defect states. Our findings represent a technological leap as they show that dislocations can be used as active building blocks in future defect-based quantum computers

Residual volatile anesthetics after workstation preparation and activated charcoal filtration

Background Volatile anesthetics potentially trigger malignant hyperthermia crises in susceptible patients. We therefore aimed to identify preparation procedures for the Draeger Primus that minimize residual concentrations of desflurane and sevoflurane with and without activated charcoal filtration. Methods A Draeger Primus test workstation was primed with 7% desflurane or 2.5% sevoflurane for 2 hours. Residual anesthetic concentrations were evaluated with five preparation procedures, three fresh gas flow rates, and three distinct applications of activated charcoal filters. Finally, non‐exchangeable and autoclaved parts of the workstation were tested for residual emission of volatile anesthetics. Concentrations were measured by multicapillary column–ion mobility spectrometry with limits of detection/quantification being <1 part per billion (ppb) for desflurane and <2.5 ppb for sevoflurane. Results The best preparation procedure included a flushing period of 10 minutes between removal and replacement of all parts of the ventilator circuit which immediately produced residual concentrations <5 ppm. A fresh gas flow of 10 L/minute reduced residual concentration as effectively as 18 L/minute, whereas flows of 1 or 5 L/minute slowed washout. Use of activated charcoal filters immediately reduced and maintained residual concentrations <5 ppm for up to 24 hours irrespective of previous workstation preparation. The fresh gas hose, circle system, and ventilator diaphragm emitted traces of volatile anesthetics. Conclusion In elective cases, presumably safe concentrations can be obtained by a 10‐minute flush at ≥10 L/minute between removal and replacement all components of the airway circuit. For emergencies, we recommend using an activated charcoal filter