17,950 research outputs found
Conjugation of injections by permutations
Let X be a countably infinite set, and let f, g, and h be any three injective
self-maps of X, each having at least one infinite cycle. (For instance, this
holds if f, g, and h are not bijections.) We show that there are permutations a
and b of X such that h=afa^{-1}bgb^{-1} if and only if |X\Xf|+|X\Xg|=|X\Xh|. We
also prove a version of this statement that holds for infinite sets X that are
not necessarily countable. This generalizes results of Droste and Ore about
permutations.Comment: 27 pages, 4 figure
Flow of nitrogen-pressurized Halon 1301 in fire extinguishing systems
Halon 1301 which is a halocarbon fire extinguishing agent (CBrF3) used by the U.S. Army for vehicle fire suppression is discussed. Halon 1301 is discharged under nitrogen pressure, and the Halon-nitrogen mixture is a two phase, two component mixture that obeys compressible fluid laws and exhibits choking effects. A computer model was developed to analyze the discharge of Halon and nitrogen from a storage bottle through pipes and nozzles. The model agrees well with data from Halon 1301 discharge tests. The discharge time depends mainly on nozzle area and pipe volume, for given initial conditions. Graphs were developed for estimating discharge times. A nozzle employing multiple concentric converging/diverging nozzles was developed which gave hemispherical coverage
Low-lying Odd-parity States of the Nucleon in Lattice QCD
The world's first examination of the odd-parity nucleon spectrum at light
quark masses in 2+1 flavor lattice QCD is presented. Configurations generated
by the PACS-CS collaboration and made available through the ILDG are used, with
the lightest pion mass at 156 MeV. A novel method for tracking the individual
energy eigenstates as the quark mass changes is introduced. The success of this
approach reveals the flow of the states towards the physical masses. Using the
correlation matrix method, the two lowest-energy states revealed are found to
be in accord with the physical spectrum of Nature.Comment: 5 page
Roper Resonance in 2+1 Flavor QCD
The low-lying even-parity states of the nucleon are explored in lattice QCD
using the PACS-CS collaboration 2+1-flavor dynamical-QCD gauge-field
configurations made available through the International Lattice Datagrid
(ILDG). The established correlation-matrix approach is used, in which various
fermion source and sink smearings are utilized to provide an effective basis of
interpolating fields to span the space of low-lying energy eigenstates. Of
particular interest is the nature of the first excited state of the nucleon,
the Roper resonance of pion-nucleon scattering. The Roper
state of the present analysis approaches the physical mass, displaying
significant chiral curvature at the lightest quark mass. These full QCD
results, providing the world's first insight into the nucleon mass spectrum in
the light-quark regime, are significantly different from those of quenched QCD
and provide interesting insights into the dynamics of QCD.Comment: 7 pages, 5 figures. Revised version with new results to appear in PL
Preparation and Characterization of Cerium (III) Doped Captopril Nanoparticles and Study of their Photoluminescence Properties
Indexación: Web of Science. DOAJ.In this research Ce3+ doped Captopril nanoparticles (Ce3+ doped CAP-NP) were prepared by a cold welding process and have been studied. Captopril may be applied in the treatment of hypertension and some types of congestive heart failure and for preventing kidney failure due to high blood pressure and diabetes. CAP-NP was synthesized by a cold welding process. The cerium nitrate was added at a ratio of 10% and the optical properties have been studied by photoluminescence (PL). The synthesized compounds were characterized by Fourier transform infrared spectroscopy. The size of CAP-NP was calculated by X-ray diffraction (XRD). The size of CAP-NP was in the range of 50 nm. Morphology of surface of synthesized nanoparticles was studied by scanning electron microscopy (SEM). Finally the luminescence properties of undoped and doped CAP-NP were compared. PL spectra from undoped CAP-NP show a strong pack in the range of 546 nm after doped cerium ion into the captopril appeared two bands at 680 and 357 nm, which is ascribed to the well-known 5d–4f emission band of the cerium.http://www.degruyter.com/view/j/chem.2016.14.issue-1/chem-2016-0008/chem-2016-0008.xm
A method for determining landing runway length for a STOL aircraft
Based on data obtained from flight tests of the augmentor wing jet STOL research aircraft, a method is proposed for determining the length of the landing runway for powered-lift STOL aircraft. The suggested method determines runway landing length by summing three segments: the touchdown-dispersion distance, the transition distance from touchdown to application of brakes, and the stopping distance after brakes are applied. It is shown how the landing field length can be reduced either through improved autoland system design or by providing the pilot with appropriate information to allow him to identify a "low probability" long or short landing and to execute a go-around. The proposed method appears to determine a safe runway landing length for the STOL application and offers the potential for reducing runway length if great emphasis is placed on a short-runway capability. FAR Parts 25 and 121 appear conservative and suitable for the situation where no great emphasis is placed on reducing the runway length requirement
Random division of an interval
The well-known relation between random division of an interval and the Poisson process is interpreted as a Laplace transformation. With the use of this interpretation a number of (in part known) results is derived very easily
PREPARATION, IDENTIFICATION AND BIOLOGICAL PROPERTIES OF NEW FLUORIDE NANOCOMPOUNDS
Indexación: Web of Science; Scopus.Nanoparticles (NPs) of new fluoride (SrF2 and MgF2) nanocompounds were synthesized by the simple chemical method of precipitation in ethanol. Synthesis of the strontium fluoride (SrF2)-magnesium oxide (MgO) nanocomposite was achieved through the ultrasonic method. These prepared nanopowders were characterized through Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, Powder X-ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). FT-IR confirmed the purity of the synthesized fluoride NPs by evaluation of the vibrations, and UV-Visible showed the intense absorption peaks of NPs. PXRD analysis indicated the average of particle size, and SEM demonstrated a nearly spherical morphology of the NPs. The antibacterical properties of the nanopowders on Staphylococcus Aureus, Bacillus Subtilis and E. Aklay bacteria were studied, with the strongest effect by the magnesium fluoride (MgF2) NPs and the SrF2-MgO nanocomposite.http://ref.scielo.org/yfr3f
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