33,819 research outputs found
Two-photon exchange model for production of neutral meson pairs in e+e- annihilation
A vector-dominance two-photon exchange model is proposed to explain the
recently observed production of and pairs in
annihilation at 10.58 GeV with the BaBar detector. All the observed
features of the data --angular and decay distributions, rates-- are in
agreement with the model. Predictions are made for yet-unobserved final states.Comment: 7 pages, 2 figures, 1 tabl
Millipeds from the eastern Dakotas and western Minnesota, USA, with an account of Pseudopolydesmus serratus (Say, 1821) (Polydesmida: Polydesmidae); first published records from six states and the District of Columbia
The diplopod orders Callipodida and Polydesmida, and their respective families Abacionidae and
Xystodesmidae, are initially recorded from South Dakota as is Polydesmidae from North Dakota. Other new records of
indigenous taxa include Abacion Rafinesque, 1820/A. texense (Loomis, 1937) and Pleuroloma/P. flavipes, both by
Rafinesque, 1820, from South Dakota, and Pseudopolydesmus Attems, 1898/P. serratus (Say, 1821) from Alabama,
Connecticut, Delaware, New Hampshire, North Dakota, South Carolina, and the District of Columbia. New records of
Aniulus garius Chamberlin, 1912, A. (Hakiulus) d. diversifrons (Wood, 1867), and Oriulus venustus (Wood, 1864)
(Julida: Parajulidae) are provided for western Minnesota and/or eastern North Dakota. Published records from these
states are summarized, and the introduced taxa, Julidae/Cylindroiulus Verhoeff, 1894/C. caeruleocinctus (Wood, 1864)
and Paradoxosomatidae/Oxidus Cook, 1911/O. gracilis (C. L. Koch, 1847), are newly recorded from the Dakotas. The
distribution of P. serratus, which extends from Maine to South Carolina and the Florida panhandle, west to Texas, and
north to Fargo, North Dakota is described and discussed. This distribution exhibits a prominent southeastern lacuna
which we hypothesize suggests replacement by younger, more successful species, as postulated for a similar distributional
gap in Scytonotus granulatus (Say, 1821)
The Navy/NASA Engine Program (NNEP89): A user's manual
An engine simulation computer code called NNEP89 was written to perform 1-D steady state thermodynamic analysis of turbine engine cycles. By using a very flexible method of input, a set of standard components are connected at execution time to simulate almost any turbine engine configuration that the user could imagine. The code was used to simulate a wide range of engine cycles from turboshafts and turboprops to air turborockets and supersonic cruise variable cycle engines. Off design performance is calculated through the use of component performance maps. A chemical equilibrium model is incorporated to adequately predict chemical dissociation as well as model virtually any fuel. NNEP89 is written in standard FORTRAN77 with clear structured programming and extensive internal documentation. The standard FORTRAN77 programming allows it to be installed onto most mainframe computers and workstations without modification. The NNEP89 code was derived from the Navy/NASA Engine program (NNEP). NNEP89 provides many improvements and enhancements to the original NNEP code and incorporates features which make it easier to use for the novice user. This is a comprehensive user's guide for the NNEP89 code
Parametric dependence of ion temperature and relative density in the NASA Lewis SUMMA facility
Further hot-ion plasma experiments were conducted in the SUMMA superconducting magnetic mirror facility. A steady-state ExB plasma was formed by applying a strong radially inward dc electric field between cylindrical anodes and hollow cathodes located near the magnetic mirror maxima. Extending the use of water cooling to the hollow cathodes, in addition to the anodes, resulted in higher maximum power input to the plasma. Steady-state hydrogen plasmas with ion kinetic temperatures as high as 830 eV were produced. Functional relations were obtained empirically among the plasma current, voltage, magnetic flux density, ion temperature, and relative ion density. The functional relations were deduced by use of a multiple correlation analysis. Data were obtained for midplane magnetic fields from 0.5 to 3.37 tesla and input power up to 45 kW. Also, initial absolute electron density measurements are reported from a 90 deg Thomson scattering laser system
Common Ground: Exploring the intersection between information, technology, art and design
University research is becoming increasingly multidisciplinary in
both the nature of the problems being investigated and the makeup
of the teams of researchers that tackle these complex
challenges. Information schools are in a unique position to
participate across a range of these projects. This poster describes
an initiative to discover potential areas for collaboration between
Syracuse University???s iSchool and the College of Visual and
Performing Arts, focusing on the synergies between information,
technology, art and design
A Search for Biomolecules in Sagittarius B2 (LMH) with the ATCA
We have used the Australia Telescope Compact Array to conduct a search for
the simplest amino acid, glycine (conformers I and II), and the simple chiral
molecule propylene oxide at 3-mm in the Sgr B2 LMH. We searched 15 portions of
spectrum between 85 and 91 GHz, each of 64 MHz bandwidth, and detected 58
emission features and 21 absorption features, giving a line density of 75
emission lines and 25 absorption lines per GHz stronger than the 5 sigma level
of 110 mJy. Of these, 19 are transitions previously detected in the
interstellar medium, and we have made tentative assignments of a further 23
features to molecular transitions. However, as many of these involve molecules
not previously detected in the ISM, these assignments cannot be regarded with
confidence. Given the median line width of 6.5 km/s in Sgr B2 LMH, we find that
the spectra have reached a level where there is line confusion, with about 1/5
of the band being covered with lines. Although we did not confidently detect
either glycine or propylene oxide, we can set 3 sigma upper limits for most
transitions searched. We also show that if glycine is present in the Sgr B2 LMH
at the level of N = 4 x 10^{14} cm^{-2} found by Kuan et al. (2003) in their
reported detection of glycine, it should have been easily detected with the
ATCA synthesized beam size of 17.0 x 3.4 arcsec^{2}, if it were confined to the
scale of the LMH continuum source (< 5 arcsec). This thus puts a strong upper
limit on any small-scale glycine emission in Sgr B2, for both of conformers I
and II.Comment: 12 pages, 2 figures, 5 tables, accepted by MNRA
Phage and host genetic determinants of the specific anticodon loop cleavages in bacteriophage T4-infected Escherichia coli CTr5X
Understanding Heisenberg's 'Magical' Paper of July 1925: a New Look at the Calculational Details
In July 1925 Heisenberg published a paper [Z. Phys. 33, 879-893 (1925)] which
ended the period of `the Old Quantum Theory' and ushered in the new era of
Quantum Mechanics. This epoch-making paper is generally regarded as being
difficult to follow, perhaps partly because Heisenberg provided few clues as to
how he arrived at the results which he reported. Here we give details of
calculations of the type which, we suggest, Heisenberg may have performed. We
take as a specific example one of the anharmonic oscillator problems considered
by Heisenberg, and use our reconstruction of his approach to solve it up to
second order in perturbation theory. We emphasize that the results are
precisely those obtained in standard quantum mechanics, and suggest that some
discussion of the approach - based on the direct computation of transition
amplitudes - could usefully be included in undergraduate courses in quantum
mechanics.Comment: 24 pages, no figures, Latex, submitted to Am. J. Phy
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