Investigation of the aerodynamic characteristics and wing-deployment transients of the NASA DL-4 body with a sailwing landing aid Final report

Aerodynamic characteristics and wing deployment transients of NASA DL-4 lifting body fitted with sailwing landing ai

The quasi-free-standing nature of graphene on H-saturated SiC(0001)

We report on an investigation of quasi-free-standing graphene on 6H-SiC(0001) which was prepared by intercalation of hydrogen under the buffer layer. Using infrared absorption spectroscopy we prove that the SiC(0001) surface is saturated with hydrogen. Raman spectra demonstrate the conversion of the buffer layer into graphene which exhibits a slight tensile strain and short range defects. The layers are hole doped (p = 5.0-6.5 x 10^12 cm^(-2)) with a carrier mobility of 3,100 cm^2/Vs at room temperature. Compared to graphene on the buffer layer a strongly reduced temperature dependence of the mobility is observed for graphene on H-terminated SiC(0001)which justifies the term "quasi-free-standing".Comment: 3 pages, 3 figures, accepted for publication in Applied Physics Letter

The Insula and Its Epilepsies

Insular seizures are great mimickers of seizures originating elsewhere in the brain. The insula is a highly connected brain structure. Seizures may only become clinically evident after ictal activity propagates out of the insula with semiology that reflects the propagation pattern. Insular seizures with perisylvian spread, for example, manifest first as throat constriction, followed next by perioral and hemisensory symptoms, and then by unilateral motor symptoms. On the other hand, insular seizures may spread instead to the temporal and frontal lobes and present like seizures originating from these regions. Due to the location of the insula deep in the brain, interictal and ictal scalp electroencephalogram (EEG) changes can be variable and misleading. Magnetic reso- nance imaging, magnetic resonance spectroscopy, magnetoencephalography, positron emission tomography, and single-photon computed tomography imaging may assist in establishing a diagnosis of insular epilepsy. Intracranial EEG recordings from within the insula, using stereo-EEG or depth electrode techniques, can prove insular seizure origin. Seizure onset, most commonly seen as low-voltage, fast gamma activity, however, can be highly localized and easily missed if the insula is only sparsely sampled. Moreover, seizure spread to the contralateral insula and other brain regions may occur rapidly. Extensive sampling of the insula with multiple electrode trajectories is necessary to avoid these pitfalls. Understanding the functional organization of the insula is helpful when interpreting the semiology produced by insular seizures. Electrical stimulation mapping around the central sulcus of the insula results in paresthesias, while stimulation of the posterior insula typically produces painful sensations. Visceral sensations are the next most common result of insular stimulation. Treatment of insular epilepsy is evolving, but poses challenges. Surgical resections of the insula are effective but risk significant morbidity if not carefully planned. Neurostimulation is an emerging option for treatment, especially for seizures with onset in the posterior insula. The close association of the insula with marked autonomic changes has led to interest in the role of the insula in sudden unexpected death in epilepsy and warrants additional study with larger patient cohorts

Wissenschaftliche, technologische und finanzielle investitionen und interaktionen europäischer Staaten im Zarenreich und die Vorzeichen des Ersten Weltkriegs seit der zweiten Hälfte des 19. Jh.

Translated by Andrey Keller. The article was submitted on 01.07.2015.Study of Russia’s cooperation with Western European countries prior to World War I is of considerable importance to understand its economic condition. Investments of various types testify that Russia was a reliable partner capable both of absorbing those investments, and of using new advanced technologies. Cheap labor and policy of the government also contributed to high status of Russia as a country to invest in. Referring to archival materials, the author provides data on the amount of investments and the return thereon, and explains foreign investors’ interest in certain spheres of Russia’s economy. Additionally, the article focuses on the infrastructure of investment in Russia and abroad, the limitations and measures against adventurism and fraud introduced by the state. The author enumerates reasons for the foreign cultural and scientific presence, introduces data on expeditions and archaeological research. The historical and biographic aspect of investment process is based on information on businessmen’s lives. Finally, the article presents a review of reports made at a Symposium on European investments into Russia and precursors of the World War I in Vienna (September, 2014) and describes urgent issues of the technological and sociocultural interaction in this research field.Изучение взаимодействия России и западноевропейских держав перед Первой мировой войной существенно дополняет представление о ее экономическом состоянии. Факты инвестирования разного характера свидетельствуют о высоком статусе России как надежного партнера в их освоении, вполне способного применять новые передовые технологии. Этому же способствовало наличие дешевой рабочей силы и политика государства. Конкретные данные о размере вложений и получаемых инвесторами дивидендах приводятся на основании архивных материалов. Выявляется логика обращения иностранцев к конкретным сферам российского хозяйства, определяются параметры оценки перспективности. Рассматривается инфраструктура инвестирования в России и за рубежом, фиксируются вводимые государством ограничения и меры против авантюризма и обмана. Конкретизируются сведения о культурных и научных целях иностранного присутствия, об организации экспедиций и археологических изысканиях. Автором рассматривается историко-биографический аспект процесса инвестирования, основаный на конкретных сведениях о жизни бизнесменов. Дается обзор докладов, прозвучавших на симпозиуме «Научные, технологические и финансовые инвестиции европейских государств в России и предвестники Первой мировой войны» (Вена, сентябрь 2014 г.), и обрисовываются актуальные проблемы технологического и социокультурного взаимодействия в исследовательском поле настоящего и будущего

Die Universität Rostock 1945 - 1946: Entnazifizierung und Wiedereröffnung

Im vorliegenden Band werden zwei Untersuchungen von Nachwuchswissenschaftlern über die unmittelbare Nachkriegsgeschichte der Universität Rostock veröffentlicht. Jobst Herzig legt den Schwerpunkt auf die Entnazifizierung und widmet sich insbesondere dem Germanisten Hermann Teuchert als Fallbeispiel. Es zeigt sich, dass die Entnazifizierung nicht konsequent und geradlinig verlief, sondern von Widersprüchen und Streit um Kompetenzen gekennzeichnet war. Im Interesse der Funktionsfähigkeit von Verwaltung und Universität erwiesen sich Zugeständnisse wiederholt als notwendig. Catharina Trost schildert den spannenden und spannungsgeladenen Prozess der Wiedereröffnung der Universität Rostock im Februar 1946 und rückt insbesondere den ersten Nachkriegsrektor, Kurt Wacholder, in den Mittelpunkt ihrer Betrachtung. Klar weist sie seine Verdienste nach und kann gängige Vorurteile über den angeblichen „Reaktionär” widerlegen

Steuerung der Bauteileigenspannungen beim Voll-Vorwärts-Fließpressen durch Stofffluss und Tribologie – Experiment und Modellierung

The forward rod extrusion of ferritic stainless steel X6Cr17 (DIN 1.4016) is here investigated with the objectives to experimentally identify and numerically verify the effect of the lubrication system and die opening angle on residual stresses. Three lubricants – MoS2, soap and polymer – are considered whose tribological properties are characterized via double cup extrusion tests. The effect of material flow is also studied by forming in conical dies featuring three different opening angles. The extrusion experiments revealed a decrease in the near-surface tensile stresses with decreasing friction for all the considered opening angles. An opening angle of 2α = 90° led to the highest tensile residual stresses. Both an increase to 2α = 120° and a decrease to 60° resulted in reduced tensile stresses and even a shift to compressive stresses. Furthermore, a previously developed numerical model of forward rod extrusion is optimized and validated against the experimentally measured residual stresses. The effect of the spatial and temporal discretizations of the model on the predicted residual stresses is investigated. Based on the experimental and numerically verified results, the recommendation to reduce friction in forward rod extrusion is derived as a means to obtain a less detrimental to the lifecycle of extruded parts residual stress state.In diesem Beitrag wird das Ziel verfolgt, an einem Voll-Vorwärts-Fließpress-Prozess die Einflüsse des verwendeten Schmiersystems und des Stoffflusses auf die Eigenspannungen experimentell zu identifizieren und numerisch abzubilden. In den Untersuchungen werden drei Schmierstoffe – MoS2, Seife und Polymer – verwendet, deren tribologische Eigenschaften im Double-Cup-Extrusion-Versuch ermittelt werden. Der Stoffflusseinfluss wird durch die Verwendung von drei Matrizenöffnungswinkeln untersucht. Die Umformversuche zeigten abnehmende oberflächennahe Zugeigenspannungen mit abnehmender Reibung für alle untersuchten Schulteröffnungswinkel. Ein Schulteröffnungswinkel von 2α = 90° führte zu den höchsten Zugeigenspannungen. Sowohl eine Erhöhung auf 120° als auch eine Reduktion auf 60° resultierten in verringerten Zug- oder sogar geringen Druchspannungen. Darüber hinaus wurde ein zuvor entwickeltes numerisches Vorwärtsfließpressmodell optimiert und anhand der experimentell ermittelten Eigenspannungen validiert. Der Einfluss der räumlichen und zeitlichen Diskretisierung des Modells auf die vorhergesagten Eigenspannungen wurde untersucht. Auf Basis der experimentell erarbeiteten und numerisch verifizierten Erkenntnisse wurde die Empfehlung abgeleitet, die auftretende Reibung zu verringern, um den Eigenspannungszustand fließgepresster Bauteile zu verbessern

Correlation Structures of Correlated Binomial Models and Implied Default Distribution

We show how to analyze and interpret the correlation structures, the conditional expectation values and correlation coefficients of exchangeable Bernoulli random variables. We study implied default distributions for the iTraxx-CJ tranches and some popular probabilistic models, including the Gaussian copula model, Beta binomial distribution model and long-range Ising model. We interpret the differences in their profiles in terms of the correlation structures. The implied default distribution has singular correlation structures, reflecting the credit market implications. We point out two possible origins of the singular behavior.Comment: 16 pages, 7 figure

Moody's Correlated Binomial Default Distributions for Inhomogeneous Portfolios

This paper generalizes Moody's correlated binomial default distribution for homogeneous (exchangeable) credit portfolio, which is introduced by Witt, to the case of inhomogeneous portfolios. As inhomogeneous portfolios, we consider two cases. In the first case, we treat a portfolio whose assets have uniform default correlation and non-uniform default probabilities. We obtain the default probability distribution and study the effect of the inhomogeneity on it. The second case corresponds to a portfolio with inhomogeneous default correlation. Assets are categorized in several different sectors and the inter-sector and intra-sector correlations are not the same. We construct the joint default probabilities and obtain the default probability distribution. We show that as the number of assets in each sector decreases, inter-sector correlation becomes more important than intra-sector correlation. We study the maximum values of the inter-sector default correlation. Our generalization method can be applied to any correlated binomial default distribution model which has explicit relations to the conditional default probabilities or conditional default correlations, e.g. Credit Risk${}^{+}$, implied default distributions. We also compare some popular CDO pricing models from the viewpoint of the range of the implied tranche correlation.Comment: 29 pages, 17 figures and 1 tabl

Determination of Halogenated Flame Retardants Using Gas Chromatography with Atmospheric Pressure Chemical Ionization (APCI) and a High-Resolution Quadrupole Time-of-Flight Mass Spectrometer (HRqTOFMS).

A method to determine halogenated flame retardants was developed that utilizes gas chromatography with atmospheric chemical ionization (APCI) high-resolution quadrupole time-of-flight mass spectrometry (HRqTOFMS). The new GC-APCI-HRqTOFMS method was used to determine the presence of 65 halogenated flame retardants (HFRs) in the United Sates National Institute of Standards and Technology (NIST) organic contaminants in house dust standard reference material (SRM). The accuracy of the measurements was compared to the certified NIST value for polybrominated diphenyl ethers (PBDEs) and had an average accuracy for the 14 certified PBDEs of 109% with subpicogram detection limits (on column) from a single 1 μL injection with a run time of 18 min. SRM2585 extracts were also analyzed by GC electron ionization (EI) high-resolution mass spectrometry (HRMS), and there was an excellent correlation between the two data sets (R2 value of 0.996). The presence of 25 additional HFRs were also screened in the dust standard, and 10 were detected in concentrations above the limits of detection; these were p-TBX, PBBZ, PBT, PBEB, TDCPP, HBBZ, EHTBB, TBBPA, BEHTBP, and BTBPE. The results presented show that the proposed APCI-HRqTOFMS method was comparable and in many cases an improvement on the existing EI-HRMS method