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Measurements of wall-shear stress fields on the piston crown in an IC engine flow using fluorescent labelled micro-pillar imaging
The measurement of wall shear-stress along the crown of a moving piston is accomplished with an array of hair-like, flexible micro-pillar sensors (MPS) in an internal combustion (IC) engine during intake flow conditions. The MPS are wall-clamped flexible micro-cylinders of 20micron diameter made of polydimethylsiloxane (PDMS) positioned on the surface of a transparent planar piston crown and protruding into the boundary layer flow above the piston at a height of 390micron. Their tips are labelled with fluorophores and are illuminated with a scanning laser-sheet system that follows the piston motion in synchronous manner. The flow-induced deflection is recorded through the transparent piston crown from below with a compact shaft-mounted high-speed camera recording the fluorescent re-emitted light from the pillar tips and using the fact of optical wave-guide features of the transparent micro-pillars. The experiments were performed in a transparent 4-valve engine setup (1.6 liter Prince 2, N13B16) during the intake phase. In order to improve the temporal resolution, the running speed of the engine was scaled down using water as working liquid. A static and dynamic sensor-calibration enabled the precise measurements of the wall-shear stress distribution with the sensor array. Due to spatial resolution limits of current available compact high-speed camera the recorded region along the piston was limited to 4x2 mm2 with 8x4 pillars in full view. The recordings at 300fps show the WSS fluctuations induced by the valve-jet / piston-wall interaction in the beginning of the intake with strong wall-normal motion forming critical points in the WSS field such as saddles, nodes and foci. Over the intake cycle > CA 80° these fluctuations die out and flow is transformed into wall-parallel coherent motion prescribed by the formation of the tumble
Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures
Nitrogen is a major nutrient for all life on Earth and could plausibly play a
similar role in extraterrestrial biospheres. The major reservoir of nitrogen at
Earth's surface is atmospheric N2, but recent studies have proposed that the
size of this reservoir may have fluctuated significantly over the course of
Earth's history with particularly low levels in the Neoarchean - presumably as
a result of biological activity. We used a biogeochemical box model to test
which conditions are necessary to cause large swings in atmospheric N2
pressure. Parameters for our model are constrained by observations of modern
Earth and reconstructions of biomass burial and oxidative weathering in deep
time. A 1-D climate model was used to model potential effects on atmospheric
climate. In a second set of tests, we perturbed our box model to investigate
which parameters have the greatest impact on the evolution of atmospheric pN2
and consider possible implications for nitrogen cycling on other planets. Our
results suggest that (a) a high rate of biomass burial would have been needed
in the Archean to draw down atmospheric pN2 to less than half modern levels,
(b) the resulting effect on temperature could probably have been compensated by
increasing solar luminosity and a mild increase in pCO2, and (c) atmospheric
oxygenation could have initiated a stepwise pN2 rebound through oxidative
weathering. In general, life appears to be necessary for significant
atmospheric pN2 swings on Earth-like planets. Our results further support the
idea that an exoplanetary atmosphere rich in both N2 and O2 is a signature of
an oxygen-producing biosphere.Comment: 33 pages, 11 figures, 2 tables (includes appendix), published in
Astrobiolog
Integrated Structure and Semantics for Reo Connectors and Petri Nets
In this paper, we present an integrated structural and behavioral model of
Reo connectors and Petri nets, allowing a direct comparison of the two
concurrency models. For this purpose, we introduce a notion of connectors which
consist of a number of interconnected, user-defined primitives with fixed
behavior. While the structure of connectors resembles hypergraphs, their
semantics is given in terms of so-called port automata. We define both models
in a categorical setting where composition operations can be elegantly defined
and integrated. Specifically, we formalize structural gluings of connectors as
pushouts, and joins of port automata as pullbacks. We then define a semantical
functor from the connector to the port automata category which preserves this
composition. We further show how to encode Reo connectors and Petri nets into
this model and indicate applications to dynamic reconfigurations modeled using
double pushout graph transformation
Rapid degradation of mutant SLC25A46 by the ubiquitin-proteasome system results in MFN1/2-mediated hyperfusion of mitochondria.
SCL25A46 is a mitochondrial carrier protein that surprisingly localizes to the outer membrane and is distantly related to Ugo1. Here we show that a subset of SLC25A46 interacts with mitochondrial dynamics components and the MICOS complex. Decreased expression of SLC25A46 results in increased stability and oligomerization of MFN1 and MFN2 on mitochondria, promoting mitochondrial hyperfusion. A mutation at L341P causes rapid degradation of SLC25A46, which manifests as a rare disease, pontocerebellar hypoplasia. The E3 ubiquitin ligases MULAN and MARCH5 coordinate ubiquitylation of SLC25A46 L341P, leading to degradation by organized activities of P97 and the proteasome. Whereas outer mitochondrial membrane-associated degradation is typically associated with apoptosis or a specialized type of autophagy termed mitophagy, SLC25A46 degradation operates independently of activation of outer membrane stress pathways. Thus SLC25A46 is a new component in mitochondrial dynamics that serves as a regulator for MFN1/2 oligomerization. Moreover, SLC25A46 is selectively degraded from the outer membrane independently of mitophagy and apoptosis, providing a framework for mechanistic studies in the proteolysis of outer membrane proteins
Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases
We present a combined theoretical and experimental study of spatio-temporal
propagation effects in terahertz (THz) generation in gases using two-color
ionizing laser pulses. The observed strong broadening of the THz spectra with
increasing gas pressure reveals the prominent role of spatio-temporal reshaping
and of a plasma-induced blue-shift of the pump pulses in the generation
process. Results obtained from (3+1)-dimensional simulations are in good
agreement with experimental findings and clarify the mechanisms responsible for
THz emission
Stellar and circumstellar properties of visual binaries in the Orion Nebula Cluster
Our general understanding of multiple star and planet formation is primarily
based on observations of young multiple systems in low density regions like
Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters,
observational constraints from young binaries in those environments are
fundamental for understanding both the formation of multiple systems and
planets in multiple systems throughout the Galaxy. We build upon the largest
survey for young binaries in the Orion Nebula Cluster (ONC) which is based on
Hubble Space Telescope observations to derive both stellar and circumstellar
properties of newborn binary systems in this cluster environment. We present
Adaptive Optics spatially-resolved JHKL'-band photometry and K-band
R\,5000 spectra for a sample of 8 ONC binary systems from this database.
We characterize the stellar properties of binary components and obtain a census
of protoplanetary disks through K-L' color excess. For a combined sample of ONC
binaries including 7 additional systems with NIR spectroscopy from the
literature, we derive mass ratio and relative age distributions. We compare the
stellar and circumstellar properties of binaries in ONC with those in Tau-Aur
and Oph from samples of binaries with stellar properties derived for each
component from spectra and/or visual photometry and with a disk census obtained
through K-L color excess. The mass ratio distribution of ONC binaries is found
to be indistinguishable from that of Tau-Aur and, to some extent, to that of
Oph in the separation range 85-560\,AU and for primary mass in the range 0.15
to 0.8\,M_{\sun}.A trend toward a lower mass ratio with larger separation is
suggested in ONC binaries which is not seen in Tau-Aur binaries.The components
of ONC binaries are found to be significantly more coeval than the overall ONC
population and as coeval as components of binaries in Tau-Aur and Oph[...]Comment: Accepted for publication in Astronomy & Astrophysic
Clinical outcome and long-term follow-up after liposuction procedures
Liposuction is one of the most common aesthetic procedure used in plastic surgery. Reports are available on the results, the probable complications, and the feedback of patients. However, systematic studies dealing with these aspects using reliable large-enough data are still needed. The data comprised 116 procedures during a 6-year period up to 2005. The data were processed and categories of results were formed. Furthermore, a follow-up examination and a survey on the feedback of patients were carried out. Significant differences were identified in indications, results, and complications. The follow-up examinations and the survey showed satisfying results. In the majority of cases, surgeons were satisfied with the operations. In conclusion, if conducted by qualified surgeons in appropriate surgical conditions and postoperative care possibilities, liposuction may be considered as a reliable surgical procedure. The success of this procedure depends, however, on suitable infrastructure and operative competenc
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