246 research outputs found
Proper Motion of the Irradiated Jet HH 399 in the Trifid Nebula
HH 399 is one of the first Herbig Haro flows recognized to be irradiated by
the UV radiation of the massive O7.5 star in the Trifid nebula. We present the
proper motion of the first irradiated jet based on two epochs of HST
observations of HH 399 separated nearly by five years using H and [SII]
line filters. High proper motion with continuous velocities between 20055
and 528 \kms are detected in both lines along the 18 extent of the
jet axis. The irradiated fully-ionized jet consists of numerous knots along the
jet but also shows the evidence for a number of isolated blob-like structures
running immediately outside the jet with lower transverse velocities. The
transverse velocities combined with radial velocity measurements indicate that
the jet axis lies away from the plane of the sky by only few degrees. We argue
that the jet is fully ionized based on [SII]/H line ratio as well as
radio continuum emission detected from the full extent of the jet at 3.6cm
wavelength. The stellar mass-loss rate producing HH 399 is estimated to be
\approx 2\times10^{-6} \msol yr.Comment: 14 pages, 6 figures, ApJ (in press
Structural basis for complement factor H-linked age-related macular degeneration
This is the final version of the article. Available from the publisher via the DOI in this record.Nearly 50 million people worldwide suffer from age-related macular degeneration (AMD), which causes severe loss of central vision. A single-nucleotide polymorphism in the gene for the complement regulator factor H (FH), which causes a Tyr-to-His substitution at position 402, is linked to approximately 50% of attributable risks for AMD. We present the crystal structure of the region of FH containing the polymorphic amino acid His402 in complex with an analogue of the glycosaminoglycans (GAGs) that localize the complement regulator on the cell surface. The structure demonstrates direct coordination of ligand by the disease-associated polymorphic residue, providing a molecular explanation of the genetic observation. This glycan-binding site occupies the center of an extended interaction groove on the regulator's surface, implying multivalent binding of sulfated GAGs. This finding is confirmed by structure-based site-directed mutagenesis, nuclear magnetic resonance-monitored binding experiments performed for both H402 and Y402 variants with this and another model GAG, and analysis of an extended GAG-FH complex.B. Prosser is funded by the Wellcome Trust Structural Biology Training Program
(075415/Z/04/Z). S. Johnson and P. Roversi were funded by grants to S.M. Lea from
the Medical Research Council (MRC) of the United Kingdom (grants G0400389 and
G0400775). D. Uhrin and P.N. Barlow were funded by the Wellcome Trust (078780/
Z/05/Z). S.J. Clark was funded by an MRC Doctoral Training Account (G78/7925),
and R.B. Sim and A.J. Day were funded by MRC core funding to the MRC
Immunochemistry Unit
Contribution of corpuscular radiation to the ionization of ionosphere's D-layer
Corpuscular radiation in ionization of ionospheres- D regio
Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine
The flow field, spray penetration, and combustion in two-stroke diesel engines are described. Fuel injection begins at 345 degrees after top dead center (ATDC) and n-dodecane is used as the liquid fuel. Arrhenius kinetics is used to calculate the reaction rate term in the quasi-global combustion model. When the temperature, fuel, and oxygen mass fraction are within suitable flammability limits, combustion begins spontaneously. No spark is necessary to ignite a localized high temperature region. Compression is sufficient to increase the gaseous phase temperature to a point where spontaneous chemical reactions occur. Results are described for a swirl angle of 22.5 degrees
Join the Club - On the Attractiveness of Golf Club Membership
This paper concerns the attractiveness for member ship in Swedish golf clubs. A representative voter model is derived and the attractiveness for member ship in golf clubs estimated using a unique data set on qualities of the golf course, the quality of neighboring courses and characteristics regarding the region where the golf club is located. Characteristics and composition of population within the municipality where the club is located have a significant impact on the attractiveness of the club. The attractiveness increases as the share of number of junior members decrease. Golf is found to be a substitute to publicly financed goods. Keywords: spatial econometrics, sports, utility maximization JEL classification: D71, L83, R12
George Fox College Life, February 1977 President\u27s Annual Report
Alumni newspaper of George Fox College.https://digitalcommons.georgefox.edu/gfc_life/1030/thumbnail.jp
Investigation of rotor blade element airloads for a teetering rotor in the blade stall regime (second wind tunnel test)
A test was conducted in the NASA-Ames 7 x 10 ft low speed wind tunnel on a seven-foot diameter model of a teetering rotor. The objectives of the test were: (1) acquire pressure data for correlation with laser and flow visualization measurements; (2) explore rotor propulsive force limits by varying the advance ratio at constant lift and propulsive force coefficients; (3) obtain additional data to define the differences between teetering and articulated rotors; and (4) verify the acceleration sensitivity of experimental transducers. Results are presented
Predicate-Transformer Semantics of General Recursion
We develop the semantics of a language with arbitrary atomic statements, unbounded nondeterminacy, and mutual recursion. The semantics is expressed in weakest preconditions and weakest liberal preconditions. Individual states are not mentioned. The predicates on the state space are treated as elements of a distributive lattice. The semantics of recursion is constructed by means of the theorem of Knaster-Tarski. It is proved that the law of the excluded miracle can be preserved, if that is wanted. The universal conjunctivity of the weakest liberal precondition, and the connection between the weakest precondition and the weakest liberal precondition are proved to remain valid. Finally we treat Hoare-triple methods for proving correctness and conditional correctness of programs
Machine Learning on Large Databases: Transforming Hidden Markov Models to SQL Statements
Machine Learning is a research field with substantial relevance for many applications in different areas. Because of technical improvements in sensor technology, its value for real life applications has even increased within the last years. Nowadays, it is possible to gather massive amounts of data at any time with comparatively little costs. While this availability of data could be used to develop complex models, its implementation is often narrowed because of limitations in computing power. In order to overcome performance problems, developers have several options, such as improving their hardware, optimizing their code, or use parallelization techniques like the MapReduce framework. Anyhow, these options might be too cost intensive, not suitable, or even too time expensive to learn and realize. Following the premise that developers usually are not SQL experts we would like to discuss another approach in this paper: using transparent database support for Big Data Analytics. Our aim is to automatically transform Machine Learning algorithms to parallel SQL database systems. In this paper, we especially show how a Hidden Markov Model, given in the analytics language R, can be transformed to a sequence of SQL statements. These SQL statements will be the basis for a (inter-operator and intra-operator) parallel execution on parallel DBMS as a second step of our research, not being part of this paper
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