Reduction of the shimmy tendency of tail and nose-wheel landing gears by installation of specially designed tires

Shimmy of tail and nose wheels may be eliminated by installation of dampers and use of large trail; however, this produces construction and operational disadvantages. It is more favorable to employ, instead of the customary tail-wheel tires, tires with lesser shimmy tendency. A description of the best possible form for these tires follows: furthermore, a few general concepts regarding the effects of the condition of the tire, of the type of rolling motion, and of the landing, are discussed

Manifest für den Wahn-Sinn: warum Veränderung Wahnsinn braucht

Die Perzeptionen von Widersprüchlichkeit, für deren Einordnung Menschen oft keine anderen sinnvollen Kategorien mehr finden als jene des Wahnsinns oder der absoluten Unvernunft, unterscheiden sich vom (zugeschriebenen) Wahnsinn einer Einzelperson: Sie sind Nebenfolgen kollektiven menschlichen Handelns, welches höchst sinnvoll (rational) begründet verfolgt wurde. Auf solchen "Wahnsinn der Zeit" wird zwar viel geschimpft, aber wenige Lehren daraus gezogen. Auch wird kaum reflektiert, was man dem Wahnsinn entgegensetzen kann - egal, wie man ihn nun genau definiert. Im vorliegenden Essay, ein "Manifest für den Wahn-Sinn", wird der Wahnsinn grundsätzlich als ein soziales Konstrukt verstanden, das mit bestimmten Politiken der Herstellung, in Diskursen und Dispositiven der Macht immer neu erschaffen wird (Abschnitt 1). Unter diesen Bedingungen werden die Chancen, die in der Moderne der Nebenfolgen ("Zweite Moderne" liegen, erörtert (Abschnitt 2), um daraufhin nach den notwendigen Grundsätzen für den einzelnen Menschen zu fragen, die erforderlich sind, um eine Welt zu schaffen, die für ihn besser, weniger "wahnsinnig", dafür jedoch "richtiger" ist (Abschnitt 3). (ICI2

Neural mechanisms of auditory scene analysis in a non-mammalian animal model

University of Minnesota Ph.D. dissertation. September 2014. Major: Neuroscience. Advisor: Mark A. Bee. 1 computer file (PDF); iv, 178 pages, appendices 1-2.Healthy auditory systems perform well in quiet places where there are no overlapping sounds, but are greatly challenged in noisy environments. In these environments, all of the sounds in the "acoustic scene" combine to create a single waveform that impinges on the receiver's ear, from which the auditory system must extract some meaningful signal. A particular example of this auditory scene analysis occurs in multi-talker environments, where the acoustic scene consists of the overlapping sounds of competing signalers. The problem of communicating in multi-talker environments has been well-studied in the human hearing literature, where it is known as the cocktail party problem, but it is not unique to humans. Many non-human animals also encounter noisy social environments and have evolved to solve cocktail-party-like problems of vocal communication. However, the mechanisms that humans and other animals use to solve the problem may differ. While human and other vertebrate auditory systems share ancestral traits from their most recent common ancestor, there is evidence for divergence of auditory systems between the separate tetrapod lineages. The independent evolution of auditory systems suggests that vertebrates may have evolved ta diversity of novel solutions to cocktail-party-like problems. Traditionally, research into similar problems in other non-human animals has been limited. The aim of my dissertation research was to investigate mechanisms that enable a non-mammalian vertebrate, specifically a frog, to navigate noisy, multi-signaler environments

Understanding the Origin of the Particularly Small and Anisotropic Thermal Expansion of MOF-74

Metal-organic frameworks often display large positive or negative thermal expansion coefficients. MOF-74, a material envisioned for many applications does not display such a behavior. For this system, temperature-dependent x-ray diffraction reveals particularly small negative thermal expansion coefficients perpendicular and positive ones parallel to the hexagonally arranged pores. The observed trends are explained by combining state-of-the-art density-functional theory calculations with the Gr\"uneisen theory of thermal expansion, which allows tracing back thermal expansion to contributions of individual phonons. On the macroscopic level, the small thermal expansion coefficients arise from two aspects: compensation effects caused by the large coupling between stress and strain perpendicular to the pores and the small magnitudes of the mean Gr\"uneisen tensor elements, $\langle\gamma\rangle$, which provide information on how strains in the material influence its phonon frequencies. To understand the small mean Gr\"uneisen tensor in MOF-74, the individual mode contributions are analyzed based on the corresponding atomic motions. This reveals that only the lowest frequency modes up to ~3 THz provide non-negligible contributions, such that $\langle\gamma\rangle$ drops sharply at higher temperatures. These considerations reveal how the details of the anharmonic properties of specific phonon bands determine the magnitude and sign of thermal expansion in a prototypical material like MOF-74

Bedarfsorientierte Curriculumentwicklung aus der Praxis für die Praxis am Beispiel der Entwicklung eines weiterbildenden Masters of Public Management

Die Verzahnung von Ansprüchen beruflicher Praxis und Wissenschaftlichkeit ist kennzeichnend für die Grundkonzeption weiterbildender Studiengänge. Während berufsbildende Lehr-Lernkonzepte von Beruflichkeit und dem Einbezug von Erfahrungswissen gekennzeichnet sind, verlangt Wissenschaftlichkeit disziplinspezifische Inhalte, Theorien und methodologische (Forschungs-)Zugänge. Um die Herausforderungen dieser Verzahnung zu illustrieren, wird im folgenden Beitrag ein bedarfsorientiertes Gestaltungskonzept am Beispiel der Entwicklung eines Masters of Public Management Sozialversicherung an der Hochschule der Deutschen Gesetzlichen Unfallversicherung (HGU) präsentiert

The murine catecholamine methyltransferase mTOMT is essential for mechanotransduction by cochlear hair cells

Hair cells of the cochlea are mechanosensors for the perception of sound. Mutations in the LRTOMT gene, which encodes a protein with homology to the catecholamine methyltransferase COMT that is linked to schizophrenia, cause deafness. Here, we show that Tomt/Comt2, the murine ortholog of LRTOMT, has an unexpected function in the regulation of mechanotransduction by hair cells. The role of mTOMT in hair cells is independent of mTOMT methyltransferase function and mCOMT cannot substitute for mTOMT function. Instead, mTOMT binds to putative components of the mechanotransduction channel in hair cells and is essential for the transport of some of these components into the mechanically sensitive stereocilia of hair cells. Our studies thus suggest functional diversification between mCOMT and mTOMT, where mTOMT is critical for the assembly of the mechanotransduction machinery of hair cells. Defects in this process are likely mechanistically linked to deafness caused by mutations in LRTOMT/Tomt

GATA6 Levels Modulate Primitive Endoderm Cell Fate Choice and Timing in the Mouse Blastocyst

SummaryCells of the inner cell mass (ICM) of the mouse blastocyst differentiate into the pluripotent epiblast or the primitive endoderm (PrE), marked by the transcription factors NANOG and GATA6, respectively. To investigate the mechanistic regulation of this process, we applied an unbiased, quantitative, single-cell-resolution image analysis pipeline to analyze embryos lacking or exhibiting reduced levels of GATA6. We find that Gata6 mutants exhibit a complete absence of PrE and demonstrate that GATA6 levels regulate the timing and speed of lineage commitment within the ICM. Furthermore, we show that GATA6 is necessary for PrE specification by FGF signaling and propose a model where interactions between NANOG, GATA6, and the FGF/ERK pathway determine ICM cell fate. This study provides a framework for quantitative analyses of mammalian embryos and establishes GATA6 as a nodal point in the gene regulatory network driving ICM lineage specification

Self-organization of the in vitro attached human embryo

Implantation of the blastocyst is a developmental milestone in mammalian embryonic development. At this time, a coordinated program of lineage diversification, cell-fate specification, and morphogenetic movements establishes the generation of extra-embryonic tissues and the embryo proper, and determines the conditions for successful pregnancy and gastrulation. Despite its basic and clinical importance, this process remains mysterious in humans. Here we report the use of a novel in vitro system1,2 to study the post-implantation development of the human embryo. We unveil the self-organizing abilities and autonomy of in vitro attached human embryos. We find human-specific molecular signatures of early cell lineage, timing, and architecture. Embryos display key landmarks of normal development, including epiblast expansion, lineage segregation, bi-laminar disc formation, amniotic and yolk sac cavitation, and trophoblast diversification. Our findings highlight the species-specificity of these developmental events and provide a new understanding of early human embryonic development beyond the blastocyst stage. In addition, our study establishes a new model system relevant to early human pregnancy loss. Finally, our work will also assist in the rational design of differentiation protocols of human embryonic stem cells to specific cell types for disease modelling and cell replacement therapy

Cell-cell interactions: Clues to hepatocyte heterogeneity and beyond?

We previously demonstrated that glutamine synthetase (GS) and ornithine aminotransferase (OAT) mRNAs are expressed in the mouse liver acinus preferentially in pericentral hepatocytes, that is, those immediately surrounding terminal central veins (A. L. Bennett, K. E. Paulson, R. E. Miller, and J. E. Darnell, Jr., J. Cell Biol. 105:1073–1085, 1987, and F. C. Kuo, W. L. Hwu, D. Valle, and J. E. Darnell, Jr., Proc. Natl. Acad. Sci. USA, (in press). We now show that hepatocytes surrounding large collecting hepatic veins but not portal veins also express these two mRNAs. The pericentral hepatocytes are the most distal hepatocytes with respect to acinar blood flow, whereas this is not necessarily the case for hepatocytes next to the large collecting hepatic veins. This result implies that it is contact with some hepatic venous element which signals positional expression. In an effort to induce conditions that change relationships between hepatocytes and blood vessels, regenerating liver was studied. After surgical removal of two-thirds or more of the liver, there was no noticeable change in GS or OAT expression in the remaining liver tissue during regeneration. However, treatment with carbon tetrachloride (CCl 4 ), which specifically kills pericentral hepatocytes, completely removed GS- and OAT-containing cells and promptly halted hepatic transcription of GS. Repair of CCl 4 damage is associated with invasion of inflammatory and scavenging cells, which remove dead hepatocytes to allow regrowth. Only when hepatocytes resumed contact with pericentral veins were the pretreatment levels of OAT and GS mRNA and high levels of GS transcription restored.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38383/1/1840160334_ftp.pd