143 research outputs found
Communications technology satellite: United States experiments and disaster communications applications
Ground antennas from 0.6 to 5.0 meters in diameter were used as remote earth terminals by the United States for both wideband (television) and narrowband (voice, data) communication in conjunction with the Canadian Hermes satellite's high power transmitter. Experiments summarized cover teleconferencing and duplex videoconferencing for medical, educational, and civic purposes, as well as the remote interpretation of multilingual broadcasts from the United Nations. The capabilities of the system during real and simulated disasters at airports are assessed. Particular attention is given to miniexperiments for flood control in the Mississippi River basin and in Johnstown, Pennsylvania during the 1977 flood
Description of the SERT 2 spacecraft and mission
Performance and orbital flight plan of SERT 2 ion thruster spacecraf
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Level of evidence used in recommendations by the National Comprehensive Cancer Network (NCCN) guidelines beyond Food and Drug Administration approvals.
BackgroundA previous analysis of 113 National Comprehensive Cancer Network® (NCCN®) recommendations reported that NCCN frequently recommends beyond Food and Drug Administration (FDA)-approved indications (44 off-label recommendations) and claimed that the evidence for these recommendations was weak.MethodsIn order to determine the strength of the evidence, we carried out an in-depth re-analysis of the 44 off-label recommendations listed in the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®).ResultsOf the 44 off-label recommendations, 14 were later approved by the FDA and/or are supported by randomized controlled trial (RCT) data. In addition, 13 recommendations were either very minor extrapolations from the FDA label (n = 8) or were actually on-label (n = 5). Of the 17 remaining extrapolations, 8 were for mechanism-based agents applied in rare cancers or subsets with few available treatment options (median response rate = 43%), 7 were based on non-RCT data showing significant efficacy (>50% response rates), and 2 were later removed from the NCCN Guidelines because newer therapies with better activity and/or safety became available.ConclusionOff-label drug use is a frequent component of care for patients with cancer in the United States. Our findings indicate that when the NCCN recommends beyond the FDA-approved indications, the strength of the evidence supporting such recommendations is robust, with a significant subset of these drugs later becoming FDA approved or supported by RCT. Recommendations without RCT data are often for mechanism-based drugs with high response rates in rare cancers or subsets without effective therapies
The Effect of Planarization on Width
We study the effects of planarization (the construction of a planar diagram
from a non-planar graph by replacing each crossing by a new vertex) on
graph width parameters. We show that for treewidth, pathwidth, branchwidth,
clique-width, and tree-depth there exists a family of -vertex graphs with
bounded parameter value, all of whose planarizations have parameter value
. However, for bandwidth, cutwidth, and carving width, every graph
with bounded parameter value has a planarization of linear size whose parameter
value remains bounded. The same is true for the treewidth, pathwidth, and
branchwidth of graphs of bounded degree.Comment: 15 pages, 6 figures. To appear at the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Parameterized Edge Hamiltonicity
We study the parameterized complexity of the classical Edge Hamiltonian Path
problem and give several fixed-parameter tractability results. First, we settle
an open question of Demaine et al. by showing that Edge Hamiltonian Path is FPT
parameterized by vertex cover, and that it also admits a cubic kernel. We then
show fixed-parameter tractability even for a generalization of the problem to
arbitrary hypergraphs, parameterized by the size of a (supplied) hitting set.
We also consider the problem parameterized by treewidth or clique-width.
Surprisingly, we show that the problem is FPT for both of these standard
parameters, in contrast to its vertex version, which is W-hard for
clique-width. Our technique, which may be of independent interest, relies on a
structural characterization of clique-width in terms of treewidth and complete
bipartite subgraphs due to Gurski and Wanke
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Onset of Convection in Two Liquid Layers with Phase Change
We perform linear stability calculations for horizontal fluid bilayers that can undergo a phase transformation, taking into account both buoyancy effects and thermocapillary effects in the presence of a vertical temperature gradient. We compare the familiar case of the stability of two immiscible fluids in a bilayer geometry with the less-studied case that the two fluids represent different phases of a single-component material, e.g., the water-steam system. The two cases differ in their interfacial boundary conditions: the condition that the interface is a material surface is replaced by the continuity of mass flux across the interface, together with an assumption of thermodynamic equilibrium that in the linearized equations represents the Clausius-Clapeyron relation relating the interfacial temperature and pressures. For the two-phase case, we find that the entropy difference between the phases plays a crucial role in determining the stability of the system. For small values of the entropy difference between the phases, the two-phase system can be linearly unstable to either heating from above or below. The instability is due to the Marangoni effect in combination with the effects of buoyancy (for heating from below). For larger values of the entropy difference the two-phase system is unstable only for heating from below, and the Marangoni effect is masked by effects of the entropy difference. To help understand the mechanisms driving the instability on heating from below we have performed both long-wavelength and short-wavelength analyses of the two-phase system. The short-wavelength analysis shows that the instability is driven by a coupling between the flow normal to the interface and the latent heat generation at the interface. The mechanism for the large wavelength instability is more complicated, and the detailed form of the expansion is found to depend on the Crispation and Bond numbers as well as the entropy difference. The two-phase system allows a conventional Rayleigh-Taylor instability if the heavier fluid overlies the lighter fluid; applying a temperature gradient allows a stabilization of the interface
A New MHD Code with Adaptive Mesh Refinement and Parallelization for Astrophysics
A new code, named MAP, is written in Fortran language for
magnetohydrodynamics (MHD) calculation with the adaptive mesh refinement (AMR)
and Message Passing Interface (MPI) parallelization. There are several optional
numerical schemes for computing the MHD part, namely, modified Mac Cormack
Scheme (MMC), Lax-Friedrichs scheme (LF) and weighted essentially
non-oscillatory (WENO) scheme. All of them are second order, two-step,
component-wise schemes for hyperbolic conservative equations. The total
variation diminishing (TVD) limiters and approximate Riemann solvers are also
equipped. A high resolution can be achieved by the hierarchical
block-structured AMR mesh. We use the extended generalized Lagrange multiplier
(EGLM) MHD equations to reduce the non-divergence free error produced by the
scheme in the magnetic induction equation. The numerical algorithms for the
non-ideal terms, e.g., the resistivity and the thermal conduction, are also
equipped in the MAP code. The details of the AMR and MPI algorithms are
described in the paper.Comment: 44 pages, 16 figure
Compact Labelings For Efficient First-Order Model-Checking
We consider graph properties that can be checked from labels, i.e., bit
sequences, of logarithmic length attached to vertices. We prove that there
exists such a labeling for checking a first-order formula with free set
variables in the graphs of every class that is \emph{nicely locally
cwd-decomposable}. This notion generalizes that of a \emph{nicely locally
tree-decomposable} class. The graphs of such classes can be covered by graphs
of bounded \emph{clique-width} with limited overlaps. We also consider such
labelings for \emph{bounded} first-order formulas on graph classes of
\emph{bounded expansion}. Some of these results are extended to counting
queries
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