Toward defect-free semi-polar GaN templates on pre-structured sapphire

The microstructure of semi-polar (11–22) GaN templates grown on pre-structured r-plane sapphire by MOVPE has been characterized by TEM. Cross-sectional observations indicate that defects are generated in three regions of the layers: threading dislocations at the inclined GaN/sapphire interface, basal plane stacking faults (BSFs) at the c−-wing, BSFs and threading dislocations at the coalescence between neighboring GaN stripes. An in situ SiN interlayer deposited at an early stage of the growth is shown to be effective in blocking the propagation of dislocations, which is mainly attributed to SiN formed on the c-plane rather than on the (11–22) plane. Si-doped marker layers have been used to study the evolution of the growth front before coalescence as a function of temperature. A high growth temperature is associated with the formation of highly faceted GaN stripes. Dislocations originally running along the c-direction are bent to the [11–20] direction driven by a progressing (11–22) facet. An efficient defect reduction is realized as a result of terminating these dislocations at voids partially defined by the (11–20) facet

Analyse der Extrusionskraft mittels SpeedCEM Plus selbstadhäsiv intraradikulär inserierter Metallstifte nach Irrigation der Stiftkanäle mit verschiedenen endodontischen spüllösungen

Bei der Wurzelkanalaufbereitung wird die Keimzahl durch einen zirkulären Substanzabtrag des Wurzelkanaldentins mit mechanischen Instrumenten reduziert. Eine alleinige mechanische Aufbereitung des Kanalsystems reicht aber nicht aus, sodass die Wurzelkanäle zusätzlich während der Behandlung mit desinfizierenden Spülflüssigkeiten gespült werden müssen. Dies ermöglicht auch eine weitgehende Auflösung und ein Herausspülen von Dentinspänen und Gewebsresten. Bei endodontisch behandelten Zähnen mit einem hohen Destruktionsgrad der klinischen Krone sind zur Erhöhung der Retention einer Restauration Wurzelstifte erforderlich. Vorherige Studien haben gezeigt, dass das Retentionsverhalten unter anderem abhängig ist von Stiftgröße, Stiftdesign und Oberflächenbeschaffenheit, sowie das entsprechende Befestigungsmaterial einen Einfluss auf die Stiftverankerung hat. Für eine erleichterte Stiftzementierung lassen sich selbstadhäsive Komposite wie zum Beispiel SpeedCEM einsetzen und reduzieren die Gefahr von Zementierungsfehlern. Ziel der Studie war es, den Einfluss von verschiedenen Spüllösungen auf den Haftverbund von Wurzelstiften aus Metall mit dem selbstadhäsiven Kompostitzement SpeedCEM zu untersuchen

Wechselwirkung geladener Projektile mit einem staubigen Plasma

In dieser Dissertation wird die Wechselwirkung zwischen geladenen schweren Projektilen und einem ausgedehnten staubigen Plasma unter Schwerelosigkeit untersucht. Ein mikrometergroßes Staubprojektil stellt für ein dreidimensionales staubiges Plasma eine bewegte punktförmige Störung dar. Bisher existieren nur wenige Untersuchungen zur Wechselwirkung solcher Störungen mit ausgedehnten staubigen Plasmen, weil die punktförmige Anregung, die in zwei Dimensionen mit einem Laserstrahl erfolgt, nicht auf drei Dimensionen übertragbar ist. Daher war zunächst die Entwicklung eines geeigneten Mechanismus zur Beschleunigung von Staubpartikeln notwendig. Dieser basiert auf einem mechanischen Zahnradantrieb, mit dem Mikropartikel auf Geschwindigkeiten von bis zu mehreren Metern pro Sekunde beschleunigt werden können. Aufgrund von Agglomeration einzelner Mikropartikel weisen diese Projektile eine Größenverteilung auf. Die vorliegende Arbeit macht sich die Untersuchung der Wechselwirkung von Agglomerat-Projektilen mit der im Plasma eingefangenen Staubwolke zur Aufgabe. Es kann beobachtet werden, dass diese Projektile in der Staubwolke einen staubfreien Bereich (Cavity) erzeugen, dessen räumliches Erscheinungsbild durch die Projektilgeschwindigkeit geprägt ist. Ein subsonisches Projektil verursacht eine nahezu sphärische Cavity, ein transsonisches dagegen eine tropfenförmige, die mit wachsender Geschwindigkeit schmaler und langgezogener und im Fall eines hypersonischen Projektils vernachlässigbar klein wird. Entgegen der intuitiven Erwartung stellt sich also heraus, dass der Cavity-Radius mit wachsender Geschwindigkeit abnimmt. Diese Arbeit konzentriert sich auf die Analyse der Cavity-Dynamik der Überschallprojektile. Durch eine Zweiteilung der Wechselwirkung zwischen Projektil und Staubwolke in einen initialen Kraftstoß, durch den sich die Cavity öffnet, und den sich anschließenden elastischen Response der Staubwolke kann die Cavity-Dynamik in einem einfachen analytischen Modell beschrieben werden: Der Impulsübertrag vom Projektil auf ein einzelnes Partikel der Staubwolke erfolgt als binärer Stoß, während sich der kollektive Response der Staubwolke als gedämpfte harmonische Oszillation des Cavity-Radius darstellen lässt. Um einen tiefer gehenden Einblick in die Wechselwirkung zwischen Projektil und Staubwolke zu erhalten, der mit der räumlichen und zeitlichen Auflösung der bisherigen Diagnostiken am Experiment nicht möglich ist, wurden detaillierte Vergleiche mit Molecular Dynamics Simulationen angestellt. Diese bestätigen das entwickelte Bild der Wechselwirkung zwischen Projektil und Staubwolke.In this thesis the interaction between charged heavy projectiles and an extended dusty plasma under microgravity conditions is studied. In a three-dimensional dusty plasma a micron-sized dust projectile can be considered as a moving point-like disturbance of the dust cloud. Previous works referring to the interaction of such disturbances and an extended dusty plasma are rare since the punctual excitation technique by means of laser light that is feasible for two-dimensional dusty plasmas cannot be translated into three-dimensional systems. Thus the development of an appropriate mechanism for the acceleration of dust particles was necessary. This mechanism utilizes a cogwheel drive to accelerate microparticles to velocities of up to several meters per second. Due to agglomeration of individual microparticles the produced projectiles show a size distribution. The aim of this work is to examine the interaction between agglomerated projectiles and the dust cloud trapped in the plasma. It is observed that these projectiles generate a dust-free cavity around them, whose shape is strongly affected by the speed of the projectile. In case of a subsonic projectile the boundary of the cavity is nearly spherical. In contrast, a transsonic projectile causes a tear-drop shaped cavity, which becomes narrower and more elongated with increasing speed and in case of a hypersonic projectile the cavity size becomes negligible. Thus it turns out --contrary to intuitive expectations-- that the cavity radius decreases with increasing speed of the projectile. This thesis focuses on the analysis of the cavity dynamics of supersonic projectiles. The decomposition of the interaction between the projectile and the dust cloud allows to describe the cavity dynamics by means of a simple analytical model. It divides the initial impulse that opens the cavity from the subsequent elastic response of the dust cloud. The transferred momentum from the projectile to an individual particle of the dust cloud can be described as a binary collision, while the collective response of the dust cloud is represented as a damped harmonic oscillation of the cavity radius. To gain deeper insight into the interaction between the projectile and the dust cloud than the spatio and temporal resolution of the utilized diagnostics of the experiment allow, detailed comparisons with molecular dynamics simulations are taken into account. They confirm the developed picture of the interaction between projectile and dust cloud

Adaptive predictor-set linear model:An imputation-free method for linear regression prediction on data sets with missing values

Linear regression (LR) is vastly used in data analysis for continuous outcomes in biomedicine and epidemiology. Despite its popularity, LR is incompatible with missing data, which frequently occur in health sciences. For parameter estimation, this shortcoming is usually resolved by complete-case analysis or imputation. Both work-arounds, however, are inadequate for prediction, since they either fail to predict on incomplete records or ignore missingness-induced reduction in prediction accuracy and rely on (unrealistic) assumptions about the missing mechanism. Here, we derive adaptive predictor-set linear model (aps-lm), capable of making predictions for incomplete data without the need for imputation. It is derived by using a predictor-selection operation, the Moore–Penrose pseudoinverse, and the reduced QR decomposition. aps-lm is an LR generalization that inherently handles missing values. It is applied on a reference data set, where complete predictors and outcome are available, and yields a set of privacy-preserving parameters. In a second stage, these are shared for making predictions of the outcome on external data sets with missing entries for predictors without imputation. Moreover, aps-lm computes prediction errors that account for the pattern of missing values even under extreme missingness. We benchmark aps-lm in a simulation study. aps-lm showed greater prediction accuracy and reduced bias compared to popular imputation strategies under a wide range of scenarios including variation of sample size, goodness of fit, missing value type, and covariance structure. Finally, as a proof-of-principle, we apply aps-lm in the context of epigenetic aging clocks, linear models that predict a person's biological age from epigenetic data with promising clinical applications.</p

Likelihood ratio and posterior odds in forensic genetics: Two sides of the same coin

It has become widely accepted in forensics that, owing to a lack of sensible priors, the evidential value of matching DNA profiles in trace donor identification or kinship analysis is most sensibly communicated in the form of a likelihood ratio (LR). This restraint does not abate the fact that the posterior odds (PO) would be the preferred basis for returning a verdict. A completely different situation holds for Forensic DNA Phenotyping (FDP), which is aimed at predicting externally visible characteristics (EVCs) of a trace donor from DNA left behind at the crime scene. FDP is intended to provide leads to the police investigation helping them to find unknown trace donors that are unidentifiable by DNA profiling. The statistical models underlying FDP typically yield posterior odds (PO) for an individual possessing a certain EVC. This apparent discrepancy has led to confusion as to when LR or PO is the appropriate outcome of forensic DNA analysis to be communicated to the investigating authorities. We thus set out to clarify the distinction between LR and PO in the context of forensic DNA profiling and FDP from a statistical point of view. In so doing, we also addressed the influence of population affiliation on LR and PO. In contrast to the well-known population dependency of the LR in DNA profiling, the PO as obtained in FDP may be widely population-independent. The actual degree of independence, however, is a matter of (i) how much of the causality of the respective EVC is captured by the genetic markers used for FDP and (ii) by the extent to which non-genetic such as environmental causal factors of the same EVC are distributed equally throughout populations. The fact that an LR should be communicated in cases of DNA profiling whereas the PO are suitable for FDP does not conflict with theory, but rather reflects the immanent differences between these two forensic applications of DNA information

Origin of faceted surface hillocks on semi-polar (1 1 2 ¯ 2) GaN templates grown on pre-structured sapphire

The microstructure of semi-polar (1 1 2 2) GaN templates grown on pre-structured r-plane sapphire by metal–organic vapor phase epitaxy (MOVPE) followed by hydride vapor phase epitaxy (HVPE) has been characterised by transmission electron microscopy (TEM). It is found that dislocations originating from the inclined c-plane-like GaN/sapphire interface bend and then terminate either at the coalescence regions of the adjacent GaN stripes or at the SiO2 mask. However, the regions associated with the coalescence event during the MOVPE growth act as a source of dislocations and stacking faults in the subsequent growth process. More importantly, a direct link between the formation of a surface hillock, the presence of an inversion domain, and the preferential nucleation of randomly oriented GaN particles at a region containing a dislocation bundle originating from coalescence has been established. It is suggested that controlling the surface conditions of the MOVPE GaN layer before HVPE and optimising the HVPE nucleation process are important to avoid the surface hillocks.This work was financially supported by the European Commission (FP7) within the framework of the project “AlGaInN materials on semi-polar templates for yellow emission in solid state lighting applications” (ALIGHT) (Project no.: 280587) and by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the project “Polarization Field Control in Nitride Light Emitters” (PolarCoN).This is the accepted manuscript for a paper published in Journal of Crystal Growth Volume 415, 1 April 2015, Pages 170–175, doi: 10.1016/j.jcrysgro.2014.12.04

The Auxological and Biochemical Continuum of Short Children Born Small for Gestational Age (SGA) or with Normal Birth Size (Idiopathic Short Stature)

Objective. Retrospective single-centre analysis of growth characteristics in 182 healthy short children born small for gestational age (SGA) or appropriate for gestational age (idiopathic short stature, ISS). Methods. Birth size references from the USA and Sweden were compared, and for the classification as SGA or ISS the Swedish reference was chosen. Height, target height (TH), bone age (BA), predicted adult height (PAH), IGF-I and IGFBP-3 values were compared between SGA and ISS. Results. In the combined group, birth weight and length showed a symmetric Gaussian distribution. The American reference overestimates the percentage of short birth length and underestimates that of low birth weight. In childhood, SGA children were shorter than ISS (−3.1 versus −2.6 SDS, P < .001), also in comparison to TH (−2.6 versus −1.9 SDS, P < .001). TH, height SDS change over time, BA delay, and PAH were similar. IGF-I and IGFBP-3 were lower in ISS (P = .03 and .09). Conclusions. SGA children represent the left tail of the Gaussian distribution of birth size in short children. The distinction between SGA and ISS depends on birth size reference. Childhood height of SGA is lower than of ISS, but the other auxological features are similar

IMHOTEP A composite score integrating popular tools for predicting the functional consequences of non-synonymous sequence variants

The in silico prediction of the functional consequences of mutations is an important goal of human pathogenetics. However, bioinformatic tools that classify mutations according to their functionality employ different algorithms so that predictions may vary markedly between tools. We therefore integrated nine popular prediction tools (PolyPhen-2, SNPs&GO, MutPred, SIFT, MutationTaster2, Mutation Assessor and FATHMM as well as conservation-based Grantham Score and PhyloP) into a single predictor. The optimal combination of these tools was selected by means of a wide range of statistical modeling techniques, drawing upon 10 029 disease-causing single nucleotide variants (SNVs) from Human Gene Mutation Database and 10 002 putatively ‘benign’ non-synonymous SNVs from UCSC. Predictive performance was found to be markedly improved by model-based integration, whilst maximum predictive capability was obtained with either random forest, decision tree or logistic regression analysis. A combination of PolyPhen-2, SNPs&GO, MutPred, MutationTaster2 and FATHMM was found to perform as well as all tools combined. Comparison of our approach with other integrative approaches such as Condel, CoVEC, CAROL, CADD, MetaSVM and MetaLR using an independent validation dataset, revealed the superiority of our newly proposed integrative approach. An online implementation of this approach, IMHOTEP (‘Integrating Molecular Heuristics and Other Tools for Effect Prediction’), is provided at http://www.uni-kiel.de/medinfo/cgi-bin/predictor/

1s2p resonant inelastic x-ray scattering in a-Fe2O3

We report experimental and theoretical results on the Fe K edge x-ray absorption spectrum and 1s2p resonant inelastic x-ray scattering (RIXS) spectra in a-Fe2O3 . The results are interpreted using an FeO6^9- cluster model with intra-atomic multiplet coupling and interatomic covalency hybridization. The 1s2p RIXS is treated as a coherent second-order optical process. It is shown that the double-peak structure in the pre-edge region of Fe K absorption spectrum is due to the cubic crystal-field splitting, and that the intensity of the eg (t2g) component in the 1s2p resonant inelastic spectrum is enhanced by tuning the incident photon energy to the eg (t2g) component in the absorption spectrum

No significantly increased frequency of the inversion polymorphism at the WBS-critical region 7q11.23 in German parents of patients with Williams-Beuren syndrome as compared to a population control

<p>Abstract</p> <p>Background</p> <p>Typical Williams-Beuren syndrome (WBS) is commonly caused by a ~1.5 Mb - ~1.8 Mb heterozygous deletion of contiguous genes at chromosome region 7q11.23. The majority of WBS cases occurs sporadically but few familial cases of autosomal dominant inheritance have been reported. Recent data demonstrated the existence of the paracentric inversion polymorphism at the WBS critical region in 7q11.23 in some of the progenitors transmitting the chromosome which shows the deletion in the affected child. In parents having a child affected by WBS the prevalence of such a structural variant has been reported to be much higher (~25- ~30%) than in the general population (~1- ~6%). However, in these previously reported studies only a limited number of randomly selected patients and non transmitting parents of WBS patients were used as controls, but without specification of any clinical data. Therefore we have undertaken a German population-based molecular cytogenetic investigation. We evaluated the incidence of the paracentric inversion polymorphism at 7q11.23 analyzing interphase nuclei of lymphocytes using a three color fluorescence in situ hybridization (FISH) probe.</p> <p>Results</p> <p>FISH analysis was carried out on couples with a child affected by WBS as compared to a population sample composed of different normal individuals: Control group I: couples with two healthy children, control group II: couples with fertility problems, planning ICSI and control group III: couples with two healthy children and one child with a chromosome aberration, not involving region 7q11.23. The three color FISH assay showed that the frequency of the paracentric inversion polymorphism at 7q11.23 in couples with a child affected by WBS was 20.8% (5 out of 24 pairs) as compared to 8.3% (2 out of 24 pairs, control group I), 25% (4 out of 16 pairs, control group II) and 9.1% (1 out of 11 pairs, control group III), respectively (total 7 out of 51 pairs, 13.8%). The frequencies differed between the groups, but this was statistically not significant (p > 0.05, Fisher's test).</p> <p>Conclusion</p> <p>Our results do not support the hypothesis that the paracentric inversion polymorphism at 7q11.23 is a major predisposing factor for the WBS deletion.</p