3D-Printed Scanning-Probe Microscopes with Integrated Optical Actuation and Read-Out

Scanning‐probe microscopy (SPM) is the method of choice for high‐resolution imaging of surfaces in science and industry. However, SPM systems are still considered as rather complex and costly scientific instruments, realized by delicate combinations of microscopic cantilevers, nanoscopic tips, and macroscopic read‐out units that require high‐precision alignment prior to use. This study introduces a concept of ultra‐compact SPM engines that combine cantilevers, tips, and a wide variety of actuator and read‐out elements into one single monolithic structure. The devices are fabricated by multiphoton laser lithography as it is a particularly flexible and accurate additive nanofabrication technique. The resulting SPM engines are operated by optical actuation and read‐out without manual alignment of individual components. The viability of the concept is demonstrated in a series of experiments that range from atomic‐force microscopy engines offering atomic step height resolution, their operation in fluids, and to 3D printed scanning near‐field optical microscopy. The presented approach is amenable to wafer‐scale mass fabrication of SPM arrays and capable to unlock a wide range of novel applications that are inaccessible by current approaches to build SPMs

Cryptic multiple hypotheses testing in linear models: overestimated effect sizes and the winner's curse

Fitting generalised linear models (GLMs) with more than one predictor has become the standard method of analysis in evolutionary and behavioural research. Often, GLMs are used for exploratory data analysis, where one starts with a complex full model including interaction terms and then simplifies by removing non-significant terms. While this approach can be useful, it is problematic if significant effects are interpreted as if they arose from a single a priori hypothesis test. This is because model selection involves cryptic multiple hypothesis testing, a fact that has only rarely been acknowledged or quantified. We show that the probability of finding at least one ‘significant’ effect is high, even if all null hypotheses are true (e.g. 40% when starting with four predictors and their two-way interactions). This probability is close to theoretical expectations when the sample size (N) is large relative to the number of predictors including interactions (k). In contrast, type I error rates strongly exceed even those expectations when model simplification is applied to models that are over-fitted before simplification (low N/k ratio). The increase in false-positive results arises primarily from an overestimation of effect sizes among significant predictors, leading to upward-biased effect sizes that often cannot be reproduced in follow-up studies (‘the winner's curse’). Despite having their own problems, full model tests and P value adjustments can be used as a guide to how frequently type I errors arise by sampling variation alone. We favour the presentation of full models, since they best reflect the range of predictors investigated and ensure a balanced representation also of non-significant results

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

Novel genetic loci underlying human intracranial volume identified through genome-wide association

Intracranial volume reflects the maximally attained brain size during development, and remains stable with loss of tissue in late life. It is highly heritable, but the underlying genes remain largely undetermined. In a genome-wide association study of 32,438 adults, we discovered five novel loci for intracranial volume and confirmed two known signals. Four of the loci are also associated with adult human stature, but these remained associated with intracranial volume after adjusting for height. We found a high genetic correlation with child head circumference (ρgenetic=0.748), which indicated a similar genetic background and allowed for the identification of four additional loci through meta-analysis (Ncombined = 37,345). Variants for intracranial volume were also related to childhood and adult cognitive function, Parkinson’s disease, and enriched near genes involved in growth pathways including PI3K–AKT signaling. These findings identify biological underpinnings of intracranial volume and provide genetic support for theories on brain reserve and brain overgrowth

Functional analysis of the murine Foxq1 gene and the characterisation of stomach specific genes

Im Rahmen dieser Arbeit wurde gezeigt, dass Foxq1 an der Magensäuresekretion beteiligt ist. Die durchgeführten Untersuchungen lassen dabei eine Beteiligung von Foxq1 an der Organisation des Tubulovesikeltransports bzw. der Tubulovesikelfusion mit der Canaliculusmembran innerhalb der Parietalzellen vermuten. Die Vermutung stützt sich zum einen auf die Ergebnisse der in situ Hybridisierung, die eine Lokalisation von Foxq1 in Parietalzellen der gastrischen Mucosa nachweist. Ein weiteres Indiz für diese Vermutung ist das Ergebnis der ultrastrukturellen Analysen der Parietalzellen nach Sekretagog-Stimulus. Eine Aktivierung der Magensäuresekretion durch Sekretagog-Stimulus führt in Parietalzellen von Foxq1-/--Tieren zu keiner mit Wildtypmäusen vergleichbaren Reaktion. Für die normale Magensäuresekretion ist ein Transport der Tubulovesikel innerhalb der Parietalzellen mit einer anschließenden Fusion der Vesikel mit der Canaliculusmembran unabdingbar. Im Ruhezustand konnten dagegen keine Veränderungen im ultrastrukturellen Aufbau der Parietalzellen von Foxq1-/--Mäusen gegenüber Wildtypmäusen beobachtet werden. Dies weist darauf hin, dass Foxq1 nicht an der Differenzierung der Parietalzellen beteiligt ist. Die beobachteten Phänotyp-Ähnlichkeiten zwischen Foxq1-defizienten Mäusen und Mäusen, denen das zur ERM Familie gehörige Ezrin fehlt, das eine Rolle in der Organisation des Plasmamembran-ständigen Aktinzytoskeletts spielt, liefern zusätzliche Hinweise auf die Beteiligung von Foxq1 an der Organisation des Aktinzytoskelett abhängigen Vesikeltransports bzw. der Vesikelfusion. Eine Assoziierung von Foxq1 mit der Organisation des Aktinzytoskeletts in der Zelle lassen auch die Untersuchungen der embryonalen Letalität von Foxq1-/--Mäusen und die Fehlbildung der inneren, medullaren Haarstruktur vermuten. Die embryonale Letalität, die bei etwa 50% der Foxq1-/--Embryonen beobachtet werden konnte, resultiert aus einer Fehlbildung der Ventrikel des Vorderhirns. Eine ähnliche Fehlbildung konnte auch an Wasf2-/--Embryonen gezeigt werden. Wasf2 (WAVE2) ist involviert in die Regulation der Aktin-Cytoskelett Reorganisation. Hierbei fungiert es als Mediator zwischen der Rac-Signaltransduktion und der Aktinassemblierung. Die fehlerhafte Organisation der Zellkompartimente, die in den medullaren Zellen des Haarschaftes von Satin Mäusen zu beobachten ist, und die Expression von Foxq1 in deren Vorläuferzellen (Hong et al., 2001) sind ein weiteres Indiz für die Beteiligung von Foxq1 an der Organisation des Aktin-Cytoskeletts. Die richtige Anordnung der einzelnen Zellkompartimente innerhalb der Zelle ist abhängig von Transportmechanismen, die assoziiert sind mit der Organisation des Aktin-Cytoskelett. Mit Hilfe einer subtraktiven cDNA-Bibliothek wurden Gene, die differentiell im Magen exprimiert werden, identifiziert. Nach Datenbankanalyse der identifizierten Gene wurden drei Gene für eine weitere Charakterisierung ausgewählt. Die Kriterien für diese Auswahl waren eine prädominante Expression im Magen und eine fehlende Charakterisierung der Gene in der Literatur. Für die drei ausgewählten Gene Gastrokine 2, Admp und SA11 konnte eine prädominante bzw. spezifische Expression im Magen nachgewiesen werden. Die Analyse der Expression während der prä- und postnatalen Magenentwicklung wurde für Gastrokine 2 und Admp durchgeführt. Die Gastrokine 2 Expression beginnt perinatal, während die Admp Expression ab Tag 17,5 post coitum nachzuweisen ist. Für das Gastrokine 2 Gen konnte zusätzlich mit Hilfe einer in situ Hybridisierung die Expression in Pit-Zellen der gastrischen Mucosa gezeigt werden. Eine weitere Charakterisierung dieser Gene und deren funktionelle Analyse können in Zukunft Aufschluss über die Funktion der Gene im Magen geben

Processing, Properties and Evaluation of Environmental Barrier Coatings for Oxide/Oxide Ceramic Matrix Composites

Oxide/oxide ceramic matrix composites (CMCs) are key engineering materials for high-temperature applications in oxidizing atmospheres, e.g. for next generation gas turbine combustor walls. To date commercially manufactured oxide/oxide CMCs consist of alumina and mullite fibers and matrices. However, alumina and mullite are prone to high-temperature corrosion caused by hydroxylation and subsequent decomposition in water vapour rich combustion gases. The application of environmental barrier coatings (EBCs) is considered the only way to overcome the corrosion problem and hence increase lifetime of oxide/oxide combustor walls to an acceptable level. At DLR, the development of environmental barrier coatings for porous WHIPOX-type (wound highly porous oxide) CMCs has been a focused research topic over the past years. EBC materials must exhibit superior corrosion stability with respect to alumina and mullite. But also compatibility between EBC and CMC substrate requires a careful selection of EBC materials. Environmental barrier coatings have been deposited on WHIPOX-type CMC substrates by a variety of state-of-the-art deposition techniques including electron beam physical vapor deposition (EB-PVD), vacuum plasma spraying, magnetron sputtering and chemical vapor deposition. Additionally, low-cost coating of CMCs has been performed using conventional ceramic sintering technologies. A review of DLR’s recent R&D activities will be presented with focus on EB-PVD coated model combustor wall tiles currently being evaluated in a high pressure combustor cooling rig

Adhesion Protein VSIG1 Is Required for the Proper Differentiation of Glandular Gastric Epithelia

VSIG1, a cell adhesion protein of the immunoglobulin superfamily, is preferentially expressed in stomach, testis, and certain gastric, esophageal and ovarian cancers. Here, we describe the expression patterns of three alternatively spliced isoforms of mouse Vsig1 during pre- and postnatal development of stomach and potential function of Vsig1 in differentiation of gastric epithelia. We show that isoforms Vsig1A and Vsig1B, which differ in the 39untranslated region, are expressed in the early stages of stomach development. Immunohistochemical analysis revealed that VSIG1 is restricted to the adherens junction of the glandular epithelium. The shorter transcript Vsig1C is restricted to the testis, encodes an N-terminal truncated protein and is presumably regulated by an internal promoter, which is located upstream of exon 1b. To determine whether the 59 flanking region of exon 1a specifically targets the expression of Vsig1 to stomach epithelia, we generated and analyzed transgenic mice. The 4.8-kb fragment located upstream of exon 1a was sufficient to direct the expression of the reporter gene to the glandular epithelia of transgenic stomach. To determine the role of VSIG1 during the development of stomach epithelia, an X-linked Vsig1 was inactivated in embryonic stem cells (ESCs). Although Vsig1 2/Y ESCs were only able to generate low coat color chimeric mice, no male chimeras transmitted the targeted allele to their progeny suggesting that the high contribution of Vsig1 2/Y cells leads to the lethality of chimeric embryos. Analysis of chimeric stomachs revealed the differentiation of VSIG1-null cells into squamous epithelia inside the glandular region. These results suggest that VSIG1 i