259 research outputs found
Turbine vane gas film cooling with injection in the leading edge region from a single row of spanwise angled holes
An experimental study of gas film cooling was conducted on a 3X size model turbine vane. Injection in the leading edge region was from a single row of holes angled in a spanwise direction. Measurements of the local heat flux downstream from the row of coolant holes, both with and without film coolant flow, were used to determine the film cooling performance presented in terms of the Stanton number ratio. Results for a range of coolant blowing ratio, M = 0 to 2.0, indicate a reduction in heat flux of up to 15 to 30 percent at a point 10 to 11 hole diameters downstream from injection. An optimum coolant blowing ratio corresponds to a coolant-to-freestream velocity ratio in the range of 0.5. The shallow injection angle resulted in superior cooling performance for injection closest to stagnation, while the effect of injection angle was insignificant for injection further from stagnation
Effect of an electric field on a floating lipid bilayer: a neutron reflectivity study
We present here a neutron reflectivity study of the influence of an
alternative electric field on a supported phospholipid double bilayer. We
report for the first time a reproducible increase of the fluctuation amplitude
leading to the complete unbinding of the floating bilayer. Results are in good
agreement with a semi-quantitative interpretation in terms of negative
electrostatic surface tension.Comment: 12 pages, 7 figures, 1 table accepted for publication in European
Physical Journal E Replaced with with correct bibliograph
Simplified Metrics Calculation for Soft Bit Detection in DVB-T2
The constellation rotation and cyclic quadrature component delay (RQD) technique has been adopted in the second generation terrestrial digital video broadcasting (DVB-T2) standard. It improves the system performance under severe propagation conditions, but introduces serious complexity problems in the hardware implementation of the detection process. In this paper, we present a simplified scheme that greatly reduces the complexity of the demapper by simplifying the soft bit metrics computation having a negligible overall system performance loss
From supported membranes to tethered vesicles: lipid bilayers destabilisation at the main transition
We report results concerning the destabilisation of supported phospholipid
bilayers in a well-defined geometry. When heating up supported phospholipid
membranes deposited on highly hydrophilic glass slides from room temperature
(i.e. with lipids in the gel phase), unbinding was observed around the main gel
to fluid transition temperature of the lipids. It lead to the formation of
relatively monodisperse vesicles, of which most remained tethered to the
supported bilayer. We interpret these observations in terms of a sharp decrease
of the bending rigidity modulus in the transition region, combined
with a weak initial adhesion energy. On the basis of scaling arguments, we show
that our experimental findings are consistent with this hypothesis.Comment: 11 pages, 3 figure
Efficient detection of RNA–protein interactions using tethered RNAs
The diverse localization of transcripts in cells suggests that there are many specific RNA–protein interactions that have yet to be identified. Progress has been limited, however, by the lack of a robust method to detect and isolate the RNA-binding proteins. Here we describe the use of an RNA aptamer, scaffolded to a tRNA, to create an affinity matrix that efficiently pulls down transcript-specific RNA-binding proteins from cell lysates. The addition of the tRNA scaffold to a Streptavidin aptamer (tRSA) increased binding efficiency by ∼10-fold. The tRSA system with an attached G-quartet sequence also could efficiently and specifically capture endogenous Fragile X Mental Retardation Protein (FMRP), which recognizes this RNA sequence. An alternative method, using biotinylated RNA, captured FMRP less efficiently than did our tRSA method. Finally we demonstrate the identification of novel RNA-binding proteins that interact with intron2 or 3′-UTR of the polarity protein Crumbs3 transcript. Proteins captured by these RNA sequences attached to the tRNA scaffold were identified by mass spectrometry. GFP-tagged versions of these proteins also showed specific interaction with either the Crb3 intron2 or 3′-UTR. Our tRSA technique should find wide application in mapping the RNA–protein interactome
Repression of RNA Polymerase II Transcription by a Drosophila Oligopeptide
Background: Germline progenitors resist signals that promote differentiation into somatic cells. This occurs through the transient repression in primordial germ cells of RNA polymerase II, specifically by disrupting Ser2 phosphorylation on its C-terminal domain. Methodology/Principal Findings: Here we show that contrary to expectation the Drosophila polar granule component (pgc) gene functions as a protein rather than a non-coding RNA. Surprisingly, pgc encodes a 71-residue, dimeric, alphahelical oligopeptide repressor. In vivo data show that Pgc ablates Ser2 phosphorylation of the RNA polymerase II C-terminal domain and completely suppresses early zygotic transcription in the soma. Conclusions/Significance: We thus identify pgc as a novel oligopeptide that readily inhibits gene expression. Germ cell repression of transcription in Drosophila is thus catalyzed by a small inhibitor protein
Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane
We discuss the electrostatic contribution to the elastic moduli of a cell or
artificial membrane placed in an electrolyte and driven by a DC electric field.
The field drives ion currents across the membrane, through specific channels,
pumps or natural pores. In steady state, charges accumulate in the Debye layers
close to the membrane, modifying the membrane elastic moduli. We first study a
model of a membrane of zero thickness, later generalizing this treatment to
allow for a finite thickness and finite dielectric constant. Our results
clarify and extend the results presented in [D. Lacoste, M. Cosentino
Lagomarsino, and J. F. Joanny, Europhys. Lett., {\bf 77}, 18006 (2007)], by
providing a physical explanation for a destabilizing term proportional to
\kps^3 in the fluctuation spectrum, which we relate to a nonlinear ()
electro-kinetic effect called induced-charge electro-osmosis (ICEO). Recent
studies of ICEO have focused on electrodes and polarizable particles, where an
applied bulk field is perturbed by capacitive charging of the double layer and
drives flow along the field axis toward surface protrusions; in contrast, we
predict "reverse" ICEO flows around driven membranes, due to curvature-induced
tangential fields within a non-equilibrium double layer, which hydrodynamically
enhance protrusions. We also consider the effect of incorporating the dynamics
of a spatially dependent concentration field for the ion channels.Comment: 22 pages, 10 figures. Under review for EPJ
Examining the Connections within the Startup Ecosystem: A Case Study of St. Louis
This paper documents the resurgence of entrepreneurial activity in St. Louis by reporting on the collaboration and local learning within the startup community. This activity is happening both between entrepreneurs and between organizations that provide support, such as mentoring and funding, to entrepreneurs. As these connections deepen, the strength of the entrepreneurial ecosystem grows. Another finding from the research is that activity-based events, where entrepreneurs have the chance to use and practice the skills needed to grow their businesses, are most useful. St. Louis provides a multitude of these activities, such as Startup Weekend, 1 Million Cups, Code Until Dawn, StartLouis, and GlobalHack. Some of these are St. Louis specific, but others have nationwide or global operations, providing important implications for other cities
TeCNO: Surgical Phase Recognition with Multi-Stage Temporal Convolutional Networks
Automatic surgical phase recognition is a challenging and crucial task with
the potential to improve patient safety and become an integral part of
intra-operative decision-support systems. In this paper, we propose, for the
first time in workflow analysis, a Multi-Stage Temporal Convolutional Network
(MS-TCN) that performs hierarchical prediction refinement for surgical phase
recognition. Causal, dilated convolutions allow for a large receptive field and
online inference with smooth predictions even during ambiguous transitions. Our
method is thoroughly evaluated on two datasets of laparoscopic cholecystectomy
videos with and without the use of additional surgical tool information.
Outperforming various state-of-the-art LSTM approaches, we verify the
suitability of the proposed causal MS-TCN for surgical phase recognition.Comment: 10 pages, 2 figure
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