Gas dynamics in the inner few AU around the Herbig B[e] star MWC297: Indications of a disk wind from kinematic modeling and velocity-resolved interferometric imaging

We present near-infrared AMBER (R = 12, 000) and CRIRES (R = 100, 000) observations of the Herbig B[e] star MWC297 in the hydrogen Br-gamma-line. Using the VLTI unit telescopes, we obtained a uv-coverage suitable for aperture synthesis imaging. We interpret our velocity-resolved images as well as the derived two-dimensional photocenter displacement vectors, and fit kinematic models to our visibility and phase data in order to constrain the gas velocity field on sub-AU scales. The measured continuum visibilities constrain the orientation of the near-infrared-emitting dust disk, where we determine that the disk major axis is oriented along a position angle of 99.6 +/- 4.8 degrees. The near-infrared continuum emission is 3.6 times more compact than the expected dust-sublimation radius, possibly indicating the presence of highly refractory dust grains or optically thick gas emission in the inner disk. Our velocity-resolved channel maps and moment maps reveal the motion of the Br-gamma-emitting gas in six velocity channels, marking the first time that kinematic effects in the sub-AU inner regions of a protoplanetary disk could be directly imaged. We find a rotation-dominated velocity field, where the blue- and red-shifted emissions are displaced along a position angle of 24 +/- 3 degrees and the approaching part of the disk is offset west of the star. The visibility drop in the line as well as the strong non-zero phase signals can be modeled reasonably well assuming a Keplerian velocity field, although this model is not able to explain the 3 sigma difference that we measure between the position angle of the line photocenters and the position angle of the dust disk. We find that the fit can be improved by adding an outflowing component to the velocity field, as inspired by a magneto-centrifugal disk-wind scenario.Comment: 15 pages, 13 Figure

Charakterisierung von Sc(x)Al(1-x)N-Schichten für die Anwendung in der Magnetfeldsensorik

In dieser Bachelorarbeit erfolgt eine grundlegende Charakterisierung gesputterter Sc(x)Al(1-x)N-Schichten, welche als vielversprechendes piezoelektrisches Material für die Anwendung in der Magnetfeldsensorik im Bereich mikroelektromechanischer Systeme gelten. Durch die Einbindung eines bestimmten Anteils x an Scandium in die hexagonale Struktur des AlN erfolgt eine Änderung des Bindungscharakters im Materialsystem. Aus der so ansteigenden Fähigkeit der Polarisation in der Gitterstruktur resultiert ein starker piezoelektrischer Effekt, der zusammen mit einem magnetostriktiven Material als Magnetfeldsensor fungieren soll. Eine Reihe ausgewählter Sc(x)Al(1-x)N-Proben wird mittels Röntgenphotoelektronenspektroskopie auf ihre genaue Zusammensetzung, besonders auf den Scandiumgehalt x, untersucht. Anschließend wird in Abhängigkeit von x die Gitterkonstante c der hexagonalen Struktur mit Hilfe der Röntgendiffraktometrie ermittelt. Zudem erfolgt eine optische Charakterisierung des Materials in Form der Raman- und Infrarotspektroskopie, um einen genauen Überblick der Änderung der Schwingungsbanden in Sc(x)Al(1-x)N in Abhängigkeit von x zu gewinnen. Zusätzlich können anhand der gewonnen Daten Aussagen über die kristalline Qualität der Struktur getroffen werden. Zuletzt werden die gefundenen Ergebnisse der verschiedenen Messmethoden miteinander korreliert und verglichen. Das weiterführende Ziel im Anschluss an diese Arbeit ist die genaue Quantifizierung der piezoelektrischen Reaktion von Sc(x)Al(1-x)N in mikroelektromechanischen Sensoren. Als Grundlage hierfür und für ein genaueres Verständnis des Materialsystems Sc(x)Al(1-x)N wurde diese Bachelorarbeit angefertigt.This bachelor thesis deals with the characterization of sputtered Sc(x)Al(1-x)N-layers, which promise a high piezoelectric response for implementation in microelectromechanical systems for measuring low magnetic fields. Within the integration of Scandium in the hexagonal structure of AlN, a change in binding character arises, resulting in the ability to create a high internal polarization and as a result, causing a wide piezoelectric reaction. The X-Ray Photoemission spectroscopy, implemented in this thesis, allows determining the percentage x of Scandium in different samples of Sc(x)Al(1-x)N. Afterwards, the lattice parameter c of hexagonal Sc(x)Al(1-x)N is determined in dependence of x by X-Ray Diffraction. Raman and Infrared spectroscopy allow making a point about the optical phonon modes in Sc(x)Al(1-x)N-alloys, influenced by Scandium-content x. On top, all measurements provide information about the crystal quality of the analyzed samples. The next objective during this research-project is the quantification of the piezoelectric response of Sc(x)Al(1-x)N in microelectromechanical systems, for which this bachelor thesis presents one part of the fundamental research

A Critical Appraisal of "Surgery versus Physical Therapy for a Meniscal Tear and Osteoarthritis"

"Surgery versus Physical Therapy for a Meniscal Tear and Osteoarthritis" effectively employs a randomized, controlled trial and uses credible outcome measures and statistical analyses. Current literatures from primary sources are often used in the study's defense as well. Several limitations impact this study, however. 35% of physical therapy alone group patients crossed over to surgery within one year, severely impacting the aim and goal. Physical therapy protocols were also unstandardized regarding exercises and number of treatments. Efficacy of physical therapy treatment is thus hard to conclude. Overall, many takeaways can be gained from this study's results although its limitations limit these takeaways to generalizations

Analysis of the visually detectable wear progress on ball screws

The actual progression of pitting on ball screw drive spindles is not well known since previous studies have only relied on the investigation of indirect wear effects (e. g. temperature, motor current, structure-borne noise). Using images from a camera system for ball screw drives, this paper elaborates on the visual analysis of pitting itself. Due to its direct, condition-based assessment of the wear state, an image-based approach offers several advantages, such as: Good interpretability, low influence of environmental conditions, and high spatial resolution. The study presented in this paper is based on a dataset containing the entire wear progression from original condition to component failure of ten ball screw drive spindles. The dataset is being analyzed regarding the following parameters: Axial length, tangential length, and surface area of each pit, the total number of pits, and the time of initial visual appearance of each pit. The results provide evidence that wear development can be quantified based on visual wear characteristics. In addition, using the dedicated camera system, the actual course of the growth curve of individual pits can be captured during machine operation. Using the findings of the analysis, the authors propose a formula for standards-based wear quantification based on geometric wear characteristics

Leucine and Isoleucine derivatives as bioavailable alternatives for canonical amino acids in cell culture media to enable next generation bioprocesses

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Analysis of the Visually Detectable Wear Progress on Ball Screws

The actual progression of pitting on ball screw drive spindles is not well known since previous studies have only relied on the investigation of indirect wear effects (e. g. temperature, motor current, structure-borne noise). Using images from a camera system for ball screw drives, this paper elaborates on the visual analysis of pitting itself. Due to its direct, condition-based assessment of the wear state, an image-based approach offers several advantages, such as: Good interpretability, low influence of environmental conditions, and high spatial resolution. The study presented in this paper is based on a dataset containing the entire wear progression from original condition to component failure of ten ball screw drive spindles. The dataset is being analyzed regarding the following parameters: Axial length, tangential length, and surface area of each pit, the total number of pits, and the time of initial visual appearance of each pit. The results provide evidence that wear development can be quantified based on visual wear characteristics. In addition, using the dedicated camera system, the actual course of the growth curve of individual pits can be captured during machine operation. Using the findings of the analysis, the authors propose a formula for standards-based wear quantification based on geometric wear characteristics

Pseudodoping of Metallic Two-Dimensional Materials by The Supporting Substrates

We demonstrate how hybridization between a two-dimensional material and its substrate can lead to an apparent heavy doping, using the example of monolayer TaS$_2$ grown on Au(111). Combining $\textit{ab-initio}$ calculations, scanning tunneling spectroscopy experiments and a generic model, we show that strong changes in Fermi areas can arise with much smaller actual charge transfer. This mechanism, which we refer to as pseudodoping, is a generic effect for metallic two-dimensional materials which are either adsorbed to metallic substrates or embedded in vertical heterostructures. It explains the apparent heavy doping of TaS$_2$ on Au(111) observed in photoemission spectroscopy and spectroscopic signatures in scanning tunneling spectroscopy. Pseudodoping is associated with non-linear energy-dependent shifts of electronic spectra, which our scanning tunneling spectroscopy experiments reveal for clean and defective TaS$_2$ monolayer on Au(111). The influence of pseudodoping on the formation of charge ordered, magnetic, or superconducting states is analyzed.Comment: arXiv admin note: substantial text overlap with arXiv:1609.0022

Business economics in a pandemic world : how a virus changed our economic life

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