7,282 research outputs found
Acoustical transducer calibrating system and apparatus
An acoustical transducer calibrating system includes a differential pressure actuating device having an inner chamber for applying differential pressures to the transducer, and an outer chamber for vacuum sealing. Mounted within the inner chamber is an electrostatic actuator for exciting the transducer at selected frequencies so that its sensitivity can be determined for different operating ambient pressures
Standing on the Shoulders of Giants: The Cleft Palate-Craniofacial Journal (1964-1989)Electronic Archive
Current research and clinical practice in cleft palate and craniofacial disorders âstands on the shoulders of giantsâ who came before us. To enable thirty years of seminal research articles to become digitally available to a worldwide community of students, scholars, and clinicians, a collaboration was forged in 2004 between University of Pittsburghâs Digital Research Library (DRL) and ACPA, (with the agreement of Allen Press), to create an electronic archive of the first thirty years of the Cleft Palate Craniofacial Journal . The work was performed pro bono, by all parties
On the Red-Green-Blue Model
We experimentally study the red-green-blue model, which is a sytem of loops
obtained by superimposing three dimer coverings on offset hexagonal lattices.
We find that when the boundary conditions are ``flat'', the red-green-blue
loops are closely related to SLE_4 and double-dimer loops, which are the loops
formed by superimposing two dimer coverings of the cartesian lattice. But we
also find that the red-green-blue loops are more tightly nested than the
double-dimer loops. We also investigate the 2D minimum spanning tree, and find
that it is not conformally invariant.Comment: 4 pages, 7 figure
Ariel - Volume 5 Number 1
Editors
Mark Dembert
J.D. Kanofskv
Entertainment Editor
Robert Breckenridge
Gary Kaskey
Editor Emeritus
David A. Jacoby
Photographer
Scott Kastner
Staff
Richard Blutstein
Bob Johnson
John R. Cohn
Joseph Sassani
Ken Jaffe
Bob Sklarof
A restatement of the normal form theorem for area metrics
An area metric is a (0,4)-tensor with certain symmetries on a 4-manifold that
represent a non-dissipative linear electromagnetic medium. A recent result by
Schuller, Witte and Wohlfarth provides a pointwise normal form theorem for such
area metrics. This result is similar to the Jordan normal form theorem for
(1,1)-tensors, and the result shows that any area metric belongs to one of 23
metaclasses with explicit coordinate expressions for each metaclass. In this
paper we restate and prove this result for skewon-free (2,2)-tensors and show
that in general, each metaclasses has three different coordinate
representations, and each of metaclasses I, II, ..., VI, VII need only one
coordinate representation.Comment: Updated proof of Proposition A.2 (Claim 5). Fixed typo in Theorem 6
(Metaclass XXIII
Bacterial viruses enable their host to acquire antibiotic resistance genes from neighbouring cells
Prophages are quiescent viruses located in the chromosomes of bacteria. In the human
pathogen, Staphylococcus aureus, prophages are omnipresent and are believed to be responsible
for the spread of some antibiotic resistance genes. Here we demonstrate that release of
phages from a subpopulation of S. aureus cells enables the intact, prophage-containing
population to acquire beneficial genes from competing, phage-susceptible strains present in
the same environment. Phage infection kills competitor cells and bits of their DNA are
occasionally captured in viral transducing particles. Return of such particles to the prophagecontaining
population can drive the transfer of genes encoding potentially useful traits such
as antibiotic resistance. This process, which can be viewed as âauto-transductionâ, allows
S. aureus to efficiently acquire antibiotic resistance both in vitro and in an in vivo virulence
model (wax moth larvae) and enables it to proliferate under strong antibiotic selection
pressure. Our results may help to explain the rapid exchange of antibiotic resistance genes
observed in S. aureus
Random skew plane partitions with a piecewise periodic back wall
Random skew plane partitions of large size distributed according to an
appropriately scaled Schur process develop limit shapes. In the present work we
consider the limit of large random skew plane partitions where the inner
boundary approaches a piecewise linear curve with non-lattice slopes,
describing the limit shape and the local fluctuations in various regions. This
analysis is fairly similar to that in [OR2], but we do find some new behavior.
For instance, the boundary of the limit shape is now a single smooth (not
algebraic) curve, whereas the boundary in [OR2] is singular. We also observe
the bead process introduced in [B] appearing in the asymptotics at the top of
the limit shape.Comment: 24 pages. This version to appear in Annales Henri Poincar
Supersymmetric vertex algebras
We define and study the structure of SUSY Lie conformal and vertex algebras.
This leads to effective rules for computations with superfields.Comment: 71 page
Addendum: "The Dynamics of M15: Observations of the Velocity Dispersion Profile and Fokker-Planck Models" (ApJ, 481, 267 [1997])
It has recently come to our attention that there are axis scale errors in
three of the figures of Dull et al. (1997, hereafter D97). D97 presented
Fokker-Planck models for the collapsed-core globular cluster M15 that include a
dense, centrally concentrated population of neutron stars and massive white
dwarfs, but do not include a central black hole. In this Addendum, we present
corrected versions of Figures 9, 10, and 12, and an expanded version of Figure
6. This latter figure, which shows the full run of the velocity dispersion
profile, indicates that the D97 model predictions are in good agreement with
the moderately rising HST-STIS velocity dispersion profile for M15 reported by
Gerssen et al. (2002, astro-ph/0209315). Thus, a central black hole is not
required to fit the new STIS velocity measurements, provided that there is a
sufficient population of neutron stars and massive white dwarfs. This
conclusion is consistent with the findings of Gerssen et al. (2002,
astro-ph/0210158), based on a reapplication of their Jeans equation analysis
using the corrected mass-to-light profile (Figure 12) for the D97 models.Comment: 4 pages, 4 figures, submitted to Ap
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