6,185 research outputs found
The E3 combustors: Status and challenges
The design, fabrication, and initial testing of energy efficient engine combustors, developed for the next generation of turbofan engines for commercial aircraft, are described. The combustor designs utilize an annular configuration with two zone combustion for low emissions, advanced liners for improved durability, and short, curved-wall, dump prediffusers for compactness. Advanced cooling techniques and segmented construction characterize the advanced liners. Linear segments are made from castable, turbine-type materials
Land use studies with Skylab data, August 1974
The author has identified the following significant results. Capabilities of Skylab photographic data suggest significant applications for: (1) identification and mapping of all primary, most secondary, and many tertiary land use classes; (2) stratification of the landscape for more detailed sampling; and (3) rapid updating of existing land use and vegetation maps subscaled at 1:25,000 and smaller with manual interpretation techniques. Automated thematic mapping of land use categories with electronic data processing techniques is feasible with the S-192 multispectral scanner, despite the high noise levels in many channels
Habitat width along a latitudinal gradient
We use the Chowdhury ecosystem model, one of the most complex agent-based
ecological models, to test the latitude-niche breadth hypothesis, with regard
to habitat width, i.e., whether tropical species generally have narrower
habitats than high latitude ones. Application of the model has given realistic
results in previous studies on latitudinal gradients in species diversity and
Rapoport's rule. Here we show that tropical species with sufficient vagility
and time to spread into adjacent habitats, tend to have wider habitats than
high latitude ones, contradicting the latitude-niche breadth hypothesis.Comment: 13 pages including all figures, draft for a biology journa
Quantum interference from remotely trapped ions
We observe quantum interference of photons emitted by two continuously
laser-excited single ions, independently trapped in distinct vacuum vessels.
High contrast two-photon interference is observed in two experiments with
different ion species, calcium and barium. Our experimental findings are
quantitatively reproduced by Bloch equation calculations. In particular, we
show that the coherence of the individual resonance fluorescence light field is
determined from the observed interference
A Fast Algorithm for Simulating the Chordal Schramm-Loewner Evolution
The Schramm-Loewner evolution (SLE) can be simulated by dividing the time
interval into N subintervals and approximating the random conformal map of the
SLE by the composition of N random, but relatively simple, conformal maps. In
the usual implementation the time required to compute a single point on the SLE
curve is O(N). We give an algorithm for which the time to compute a single
point is O(N^p) with p<1. Simulations with kappa=8/3 and kappa=6 both give a
value of p of approximately 0.4.Comment: 17 pages, 10 figures. Version 2 revisions: added a paragraph to
introduction, added 5 references and corrected a few typo
Optimizing Federated Queries Based on the Physical Design of a Data Lake
The optimization of query execution plans is known to be crucial
for reducing the query execution time. In particular, query optimization
has been studied thoroughly for relational databases
over the past decades. Recently, the Resource Description Framework
(RDF) became popular for publishing data on the Web. As
a consequence, federations composed of different data models
like RDF and relational databases evolved. One type of these
federations are Semantic Data Lakes where every data source is
kept in its original data model and semantically annotated with
ontologies or controlled vocabularies. However, state-of-the-art
query engines for federated query processing over Semantic Data
Lakes often rely on optimization techniques tailored for RDF. In
this paper, we present query optimization techniques guided
by heuristics that take the physical design of a Data Lake into
account. The heuristics are implemented on top of Ontario, a
SPARQL query engine for Semantic Data Lakes. Using sourcespecific
heuristics, the query engine is able to generate more efficient
query execution plans by exploiting the knowledge about
indexes and normalization in relational databases. We show that
heuristics which take the physical design of the Data Lake into
account are able to speed up query processing
A phosphatidylinositol (4,5)-bisphosphate binding site within mu 2-adaptin regulates clathrin-mediated endocytosis
The clathrin adaptor complex AP-2 serves to coordinate clathrin-coated pit assembly with the sorting of transmembrane cargo proteins at the plasmalemma. Flow precisely AP-2 assembly and cargo protein recognition at sites of endocytosis are regulated has remained unclear, but recent evidence implicates phosphoinositides, in particular phosphatidylinositol (4,5)- bisphosphate (PI[4,5]P-2) in these processes. Here we have identified and functionally characterized a conserved binding site for PI(4,5)P2 within mu2-adaptin, the medium chain of the clathrin adaptor complex AP-2. Mutant p,2 lacking a cluster of conserved lysine residues fails to bind PI(4,5)P2 and to compete the recruitment of native clathrin/AP-2 to PI(4,5)P-2- containing liposomes or to presynaptic membranes. Moreover, we show that expression of mutant mu2 inhibits receptor-mediated endocytosis in living cells. We suggest that PI(4,5)P-2 binding to mu2-adaptin regulates clathrin-mediated endocytosis and thereby may contribute to structurally linking cargo recognition to coat formation
Restriction Properties of Annulus SLE
For , a family of annulus SLE processes
were introduced in [14] to prove the reversibility of whole-plane
SLE. In this paper we prove that those annulus SLE
processes satisfy a restriction property, which is similar to that for chordal
SLE. Using this property, we construct curves crossing an
annulus such that, when any curves are given, the last curve is a chordal
SLE trace.Comment: 37 page
- âŠ