2,121 research outputs found
NORSEX 1979 microwave remote sensing data report
Airborne microwave remote sensing measurements obtained by NASA Langley Research Center in support of the 1979 Norwegian Remote Sensing Experiment (NORSEX) are summarized. The objectives of NORSEX were to investigate the capabilities of an active/passive microwave system to measure ice concentration and type in the vicinity of the marginal ice zone near Svalbard, Norway and to apply microwave techniques to the investigation of a thermal oceanic front near Bear Island, Norway. The instruments used during NORSEX include the stepped frequency microwave radiometer, airborne microwave scatterometer, precision radiation thermometer and metric aerial photography. The data are inventoried, summarized, and presented in a user-friendly format. Data summaries are presented as time-history plots which indicate when and where data were obtained as well as the sensor configuration. All data are available on nine-track computer tapes in card-image format upon request to the NASA Langley Technical Library
Stability of CFL cores in Hybrid Stars
We study the equation state of strongly interacting quark matter within a
NJL-like model in which the chiral condensates and the color superconducting
gaps are computed self-consistently as a function of the baryon density. A
vector interaction term is added to the Lagrangian in order to render the quark
matter equation of state stiffer. For the low density hadronic phase we use a
relativistic mean field model. The phase transition to quark matter is computed
by a Maxwell construction. We show that stable CFL cores in hybrid stars are
possible if the superconducting gap is sufficiently large. Moreover we find
stable stellar configurations in which two phase transitions occur, a first
transition from hadronic matter to 2SC quark matter and a second transition
from 2SC quark matter to CFL quark matter.Comment: 10 pages, 6 figure
Strange matter in core-collapse supernovae
We discuss the possible impact of strange quark matter on the evolution of
core-collapse supernovae with emphasis on low critical densities for the
quark-hadron phase transition. For such cases the hot proto-neutron star can
collapse to a more compact hybrid star configuration hundreds of milliseconds
after core-bounce. The collapse triggers the formation of a second shock wave.
The latter leads to a successful supernova explosion and leaves an imprint on
the neutrino signal. These dynamical features are discussed with respect to
their compatibility with recent neutron star mass measurements which indicate a
stiff high density nuclear matter equation of state.Comment: 8 pages, 3 figures, Invited talk at the "Strangeness in Quark Matter"
conference, 18-24 September 2011, Polish Academy of Arts and Sciences,
Cracow, Polan
Beaufort/Bering 1979 microwave remote sensing data catalog report, 14-24 March 1979
The airborne microwave remote sending measurements obtained by the Langley Research Center in support of the 1979 Sea-Ice Radar Experiment (SIRE) in the Beaufort and Bering Seas are discussed. The remote sensing objective of SIRE was to define correlations between both active and passive microwave signatures and ice phenomena assocated with practical applications in the Arctic. The instruments used by Langley during SIRE include the stepped frequency microwave radiometer (SFMR), the airborne microwave scatterometer (AMSCAT), the precision radiation thermometer (PRT-5), and metric aerial photography. Remote sensing data are inventoried and cataloged in a user-friendly format. The data catalog is presented as time-history plots when and where data were obtained as well as the sensor configuration
Formation of Quark Phases in compact stars and their connection to Gamma-Ray-Bursts
We analyse the occurrence of quiescent times in the temporal structure of the
Gamma-Ray-Bursts (GRBs) light curves. We show that if a long quiescent time is
present, it is possible to divide the total duration of GRBs into three
periods: the pre-quiescence emission, the quiescent time and the
post-quiescence emission. We then discuss a model of the GRBs inner engine
based on the formation of quark phases during the life of an hadronic star.
Within this model the pre-quiescence emission is interpreted as due to the
deconfinement of quark inside an hadronic star and the formation of 2SC quark
matter. The post-quiescence emission is due to the conversion of 2SC into the
Color-Flavor-Locking (CFL) phase. The temporal delay between these two
processes is connected with the nucleation time of the CFL phase in the 2SC
phase and it can be associated with the observed quiescent times in the GRBs
light curves. The stability of CFL cores in compact stars is also discussed.Comment: 6 pages, 3 figures, to appear in the proceedings of 3th International
Conference on Nuclear Physics in Astrophysics (NPAIII), 26 - 31 March 2007
Dresden, German
Model-based Cognitive Neuroscience: Multifield Mechanistic Integration in Practice
Autonomist accounts of cognitive science suggest that cognitive model building and theory construction (can or should) proceed independently of findings in neuroscience. Common functionalist justifications of autonomy rely on there being relatively few constraints between neural structure and cognitive function (e.g., Weiskopf, 2011). In contrast, an integrative mechanistic perspective stresses the mutual constraining of structure and function (e.g., Piccinini & Craver, 2011; Povich, 2015). In this paper, I show how model-based cognitive neuroscience (MBCN) epitomizes the integrative mechanistic perspective and concentrates the most revolutionary elements of the cognitive neuroscience revolution (Boone & Piccinini, 2016). I also show how the prominent subset account of functional realization supports the integrative mechanistic perspective I take on MBCN and use it to clarify the intralevel and interlevel components of integration
The Strange Prospects for Astrophysics
The implications of the formation of strange quark matter in neutron stars
and in core-collapse supernovae is discussed with special emphasis on the
possibility of having a strong first order QCD phase transition at high baryon
densities. If strange quark matter is formed in core-collapse supernovae
shortly after the bounce, it causes the launch of a second outgoing shock which
is energetic enough to lead to a explosion. A signal for the formation of
strange quark matter can be read off from the neutrino spectrum, as a second
peak in antineutrinos is released when the second shock runs over the
neutrinosphere.Comment: 10 pages, 8 figures, invited talk given at the international
conference on strangeness in quark matter (SQM2008), Beijing, October 6-10,
Beijing, China, version to appear in J. Phys.
Strange quark matter in explosive astrophysical systems
Explosive astrophysical systems, such as supernovae or compact star binary
mergers, provide conditions where strange quark matter can appear. The high
degree of isospin asymmetry and temperatures of several MeV in such systems may
cause a transition to the quark phase already around saturation density.
Observable signals from the appearance of quark matter can be predicted and
studied in astrophysical simulations. As input in such simulations, an equation
of state with an integrated quark matter phase transition for a large
temperature, density and proton fraction range is required. Additionally,
restrictions from heavy ion data and pulsar observation must be considered. In
this work we present such an approach. We implement a quark matter phase
transition in a hadronic equation of state widely used for astrophysical
simulations and discuss its compatibility with heavy ion collisions and pulsar
data. Furthermore, we review the recently studied implications of the QCD phase
transition during the early post-bounce evolution of core-collapse supernovae
and introduce the effects from strong interactions to increase the maximum mass
of hybrid stars. In the MIT bag model, together with the strange quark mass and
the bag constant, the strong coupling constant provides a parameter
to set the beginning and extension of the quark phase and with this the mass
and radius of hybrid stars.Comment: 6 pages, 5 figures, talk given at the International Conference on
Strangeness in Quark Matter (SQM2009), Buzios, Brasil, September 28 - October
2, 2009, to be published in Journal Phys.
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