43,779 research outputs found
The Economic impact of Florida's recreational boating industry in 1985
The recreational boating industry is an important component of Florida's economy. Previous Florida Sea Grant College supported research has documented this economic importance to the state's economy in 1980 (see Milon and Riddle, 1983, and Milon et al. 1983). Since that initial research, the manufacturing, retailing, and service sectors comprising
the industry have continued to grow and prosper as the state's resident and tourist populations increased. This report is an update on the economic significance of the recreational boating industry in Florida since 1980 based on economic indicators of change within the industry. (21pp.
Neutron star masses from hydrodynamical effects in obscured sgHMXBs
A population of obscured supergiant High Mass X-ray Binaries (sgHMXBs) has
been discovered by INTEGRAL. X-ray wind tomography of IGR J17252-3616 inferred
a slow wind velocity to account for the enhanced obscuration. The main goal of
this study is to understand under which conditions high obscuration could
occur. We have used an hydrodynamical code to simulate the flow of the stellar
wind around the neutron star. A grid of simulations was used to study the
dependency of the absorbing column density and of the X-ray light-curves on the
model parameters. A comparison between the simulation results and the
observations of IGR J17252-3616 provides an estimate on these parameters. We
have constrained the wind terminal velocity to 500-600 km/s and the neutron
star mass to 1.75-2.15 solar masses. We have confirmed that the initial
hypothesis of a slow wind velocity with a moderate mass loss rate is valid. The
mass of the neutron star can be constrained by studying its impact on the
accretion flow.Comment: A&A in pres
Multiply connected wandering domains of entire functions
The dynamical behaviour of a transcendental entire function in any periodic
component of the Fatou set is well understood. Here we study the dynamical
behaviour of a transcendental entire function in any multiply connected
wandering domain of . By introducing a certain positive harmonic
function in , related to harmonic measure, we are able to give the first
detailed description of this dynamical behaviour. Using this new technique, we
show that, for sufficiently large , the image domains contain
large annuli, , and that the union of these annuli acts as an absorbing
set for the iterates of in . Moreover, behaves like a monomial
within each of these annuli and the orbits of points in settle in the long
term at particular `levels' within the annuli, determined by the function .
We also discuss the proximity of and for large
, and the connectivity properties of the components of . These properties are deduced from new results about the behaviour
of an entire function which omits certain values in an annulus
Dynamics of meromorphic functions with direct or logarithmic singularities
We show that if a meromorphic function has a direct singularity over
infinity, then the escaping set has an unbounded component and the intersection
of the escaping set with the Julia set contains continua. This intersection has
an unbounded component if and only if the function has no Baker wandering
domains. We also give estimates of the Hausdorff dimension and the upper box
dimension of the Julia set of a meromorphic function with a logarithmic
singularity over infinity. The above theorems are deduced from more general
results concerning functions which have "direct or logarithmic tracts", but
which need not be meromorphic in the plane. These results are obtained by using
a generalization of Wiman-Valiron theory. The method is also applied to complex
differential equations.Comment: 29 pages, 2 figures; v2: some overall revision, with comments and
references added; to appear in Proc. London Math. So
Sets of Priors Reflecting Prior-Data Conflict and Agreement
In Bayesian statistics, the choice of prior distribution is often debatable,
especially if prior knowledge is limited or data are scarce. In imprecise
probability, sets of priors are used to accurately model and reflect prior
knowledge. This has the advantage that prior-data conflict sensitivity can be
modelled: Ranges of posterior inferences should be larger when prior and data
are in conflict. We propose a new method for generating prior sets which, in
addition to prior-data conflict sensitivity, allows to reflect strong
prior-data agreement by decreased posterior imprecision.Comment: 12 pages, 6 figures, In: Paulo Joao Carvalho et al. (eds.), IPMU
2016: Proceedings of the 16th International Conference on Information
Processing and Management of Uncertainty in Knowledge-Based Systems,
Eindhoven, The Netherland
HI and Hot Gas in the Outskirts of the M81 Group
Results are presented from a wide area, high resolution HI synthesis survey
of the outer regions of the nearby M81 group, where internal (galactic) and
external (group-related) evolution processes can be studied simultaneously in
great detail. The survey encompasses the star forming dwarf galaxies M81dwA,
UGC4483, and HoII, where evidence of ram pressure stripping was recently
discovered. The data do not reveal any intergalactic HI, but the outer parts of
HoII are reminiscent of tidal tails. We argue however that those structures are
equally consistent with the latest ram pressure models including cooling. The
case for a hot intergalactic medium in this poor, spiral-only group is thus
still open. The survey also puts tight constraints on possible counterparts to
the local high velocity cloud population in an external group, reaching a 3
sigma column density of 10^19 atom/cm^2 and a 6 sigma limiting mass of 1.5x10^5
M_sun.Comment: 6 pages, 3 figures, to be published in "Recycling Intergalactic and
Interstellar Matter," eds. P.-A. Duc, J. Braine, & E. Brinks (ASP: San
Francisco
Matrix product states and the quantum max-flow/min-cut conjectures
In this note we discuss the geometry of matrix product states with periodic
boundary conditions and provide three infinite sequences of examples where the
quantum max-flow is strictly less than the quantum min-cut. In the first we fix
the underlying graph to be a 4-cycle and verify a prediction of Hastings that
inequality occurs for infinitely many bond dimensions. In the second we
generalize this result to a 2d-cycle. In the third we show that the 2d-cycle
with periodic boundary conditions gives inequality for all d when all bond
dimensions equal two, namely a gap of at least 2^{d-2} between the quantum
max-flow and the quantum min-cut.Comment: 12 pages, 3 figures - Final version accepted for publication on J.
Math. Phy
Evaluation of directionally solidified eutectic superalloys for turbine blade applications
Alloys from the following systems were selected for property evaluation: (1) gamma/gamma-Mo (Ni-base, rods of Mo); (2) gamma-beta (Ni-base, lamellae or rods of (Ni, Fe/Co Al); and (3) gamma-gamma (Ni-base rods of Ni3Al gamma). The three alloys were subjected to longitudinal and transverse tensile and rupture tests from 750 C to 1100 C, longitudinal shear strength was measured at several temperatures, resistance to thermal cycling to 1150 C was determined, cyclic oxidation resistance was evaluated at 750 C and 1100 C, and each system was directionally solidified in an alumina shell mold turbine shape to evaluate mold/metal reactivity. The gamma/gamma Mo system has good rupture resistance, transverse properties and processability, and is a high potential system for turbine blades. The gamma-beta system has good physical properties and oxidation resistance, and is a potential system for turbine vanes. The gamma-gamma system has good high temperature rupture resistance and requires further exploratory research
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