7,616 research outputs found
Comparison of Magnetic Flux Distribution between a Coronal Hole and a Quiet Region
Employing Big Bear Solar Observatory (BBSO) deep magnetograms and H
images in a quiet region and a coronal hole, observed on September 14 and 16,
2004, respectively, we have explored the magnetic flux emergence, disappearance
and distribution in the two regions. The following results are obtained: (1)
The evolution of magnetic flux in the quiet region is much faster than that in
the coronal hole, as the flux appeared in the form of ephemeral regions in the
quiet region is 4.3 times as large as that in the coronal hole, and the flux
disappeared in the form of flux cancellation, 2.9 times as fast as in the
coronal hole. (2) More magnetic elements with opposite polarities in the quiet
region are connected by arch filaments, estimating from magnetograms and
H images. (3) We measured the magnetic flux of about 1000 magnetic
elements in each observing region. The flux distribution of network and
intranetwork (IN) elements is similar in both polarities in the quiet region.
For network fields in the coronal hole, the number of negative elements is much
more than that of positive elements. However for the IN fields, the number of
positive elements is much more than that of negative elements. (4) In the
coronal hole, the fraction of negative flux change obviously with different
threshold flux density. 73% of the magnetic fields with flux density larger
than 2 Gauss is negative polarity, and 95% of the magnetic fields is negative,
if we only measure the fields with their flux density larger than 20 Gauss. Our
results display that in a coronal hole, stronger fields is occupied by one
predominant polarity; however the majority of weaker fields, occupied by the
other polarity
Pretzelosity and quark orbital angular momentum
We calculate the pretzelosity distribution (), which is one
of the eight leading twist transverse momentum dependent parton distributions
(TMDs), in the light-cone formalism. We find that this quantity has a simple
relation with the quark orbital angular momentum distribution, thus it may
provide a new possibility to access the quark orbital angular momentum inside
the nucleon. The pretzelosity distribution can manifest itself through the
asymmetry in semi-inclusive deep inelastic scattering
process. We calculate the asymmetry at HERMES, COMPASS
and JLab kinematics, and present our prediction on different targets including
the proton, deuteron and neutron targets. Inclusion of transverse momentum cut
in data analysis could significantly enhance the
asymmetry for future measurements.Comment: 20 latex pages, 7 figures, to appear in PR
PATHS OF INFLUENCE FOR INNOVATIONS IN FINANCIAL IS AND TECHNOLOGY ECOSYSTEMS
Predicting technological innovations in financial information systems (IS) and technology ecosystems has been challenging for technology forecasters and industry analysts due to their underlying complexity. Technology-based financial innovations over the past four decades, such as programmed trading in the 1980s, risk-adjusted return on capital-based financial risk management systems in the 1990s, high-frequency trading and Internet banking in 2000s, and now mobile payments in the 2010s, have all led to transformations in the financial services industry. What basis can be identified to predict such new innovations? And what areas of financial services will they affect? This study applies the technology ecosystem approach, extended to incorporate stakeholders’ strategic actions, to analyse the paths of influence for mobile payment technologies. Our ecosystem model brings together three core elements: emerging technology components, technology-based services, and technologysupported business infrastructure. We will also discuss its applicability to high-frequency trading in the equity markets
Structure and dynamics of the E. coli chemotaxis core signaling complex by cryo-electron tomography and molecular simulations
To enable the processing of chemical gradients, chemotactic bacteria possess large arrays of transmembrane chemoreceptors, the histidine kinase CheA, and the adaptor protein CheW, organized as coupled core-signaling units (CSU). Despite decades of study, important questions surrounding the molecular mechanisms of sensory signal transduction remain unresolved, owing especially to the lack of a high-resolution CSU structure. Here, we use cryo-electron tomography and sub-tomogram averaging to determine a structure of the Escherichia coli CSU at sub-nanometer resolution. Based on our experimental data, we use molecular simulations to construct an atomistic model of the CSU, enabling a detailed characterization of CheA conformational dynamics in its native structural context. We identify multiple, distinct conformations of the critical P4 domain as well as asymmetries in the localization of the P3 bundle, offering several novel insights into the CheA signaling mechanism
5-Dimensional Kaluza-Klein Theory with a Source
A free test particle in 5-dimensional Kaluza-Klein spacetime will show its
electricity in the reduced 4-dimensional spacetime when it moves along the
fifth dimension. In the light of this observation, we study the coupling of a
5-dimensional dust field with the Kaluza-Klein gravity. It turns out that the
dust field can curve the 5-dimensional spacetime in such a way that it provides
exactly the source of the electromagnetic field in the 4-dimensional spacetime
after the dimensional reduction.Comment: 8 pages, three references adde
Effects of isospin and momentum dependent interactions on thermal properties of asymmetric nuclear matter
Thermal properties of asymmetric nuclear matter are studied within a
self-consistent thermal model using an isospin and momentum dependent
interaction (MDI) constrained by the isospin diffusion data in heavy-ion
collisions, a momentum-independent interaction (MID), and an isoscalar
momentum-dependent interaction (eMDYI). In particular, we study the temperature
dependence of the isospin-dependent bulk and single-particle properties, the
mechanical and chemical instabilities, and liquid-gas phase transition in hot
asymmetric nuclear matter. Our results indicate that the temperature dependence
of the equation of state and the symmetry energy are not so sensitive to the
momentum dependence of the interaction. The symmetry energy at fixed density is
found to generally decrease with temperature and for the MDI interaction the
decrement is essentially due to the potential part. It is further shown that
only the low momentum part of the single-particle potential and the nucleon
effective mass increases significantly with temperature for the
momentum-dependent interactions. For the MDI interaction, the low momentum part
of the symmetry potential is significantly reduced with increasing temperature.
For the mechanical and chemical instabilities as well as the liquid-gas phase
transition in hot asymmetric nuclear matter, our results indicate that the
boundary of these instabilities and the phase-coexistence region generally
shrink with increasing temperature and is sensitive to the density dependence
of the symmetry energy and the isospin and momentum dependence of the nuclear
interaction, especially at higher temperatures.Comment: 21 pages, 29 figure
Evidence for SU(3) symmetry breaking from hyperon production
We examine the SU(3) symmetry breaking in hyperon semileptonic decays (HSD)
by considering two typical sets of quark contributions to the spin content of
the octet baryons: Set-1 with SU(3) flavor symmetry and Set-2 with SU(3) flavor
symmetry breaking in HSD. The quark distributions of the octet baryons are
calculated with a successful statistical model. Using an approximate relation
between the quark fragmentation functions and the quark distributions, we
predict polarizations of the octet baryons produced in annihilation
and semi-inclusive deeply lepton-nucleon scattering in order to reveal the
SU(3) symmetry breaking effect on the spin structure of the octet baryons. We
find that the SU(3) symmetry breaking significantly affects the hyperon
polarization. The available experimental data on the polarization
seem to favor the theoretical predictions with SU(3) symmetry breaking. We
conclude that there is a possibility to get a collateral evidence for SU(3)
symmetry breaking from hyperon production. The theoretical errors for our
predictions are discussed.Comment: 3 tables, 14 figure
Coherent optical phase transfer over a 32-km fiber with 1-s instability at
The phase coherence of an ultrastable optical frequency reference is fully
maintained over actively stabilized fiber networks of lengths exceeding 30 km.
For a 7-km link installed in an urban environment, the transfer instability is
at 1-s. The excess phase noise of 0.15 rad, integrated from
8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link
achieves similar performance. Using frequency combs at each end of the
coherent-transfer fiber link, a heterodyne beat between two independent
ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure
Optical Monitoring of BL Lacertae Object S5 0716+714 with a Novel Multi-Peak Interference Filter
We at first introduce a novel photometric system, which consists of a Schmidt
telescope, an objective prism, a CCD camera, and, especially, a multi-peak
interference filter. The multi-peak interference filter enables light in multi
passbands to pass through it simultaneously. The light in different passbands
is differentially refracted by the objective prism and is focused on the CCD
separately, so we have multi "images" for each object on the CCD frames. This
system enables us to monitor blazars exactly simultaneously in multi wavebands
on a single telescope, and to accurately trace the color change during the
variation. We used this novel system to monitor the BL Lacertae object S5
0716+714 during 2006 January and February and achieved a very high temporal
resolution. The object was very bright and very active during this period. Two
strong flares were observed, with variation amplitudes of about 0.8 and 0.6
mags in the band, respectively. Strong bluer-when-brighter correlations
were found for both internight and intranight variations. No apparent time lag
was observed between the - and -band variations, and the observed
bluer-when-brighter chromatism may be mainly attributed to the larger variation
amplitude at shorter wavelength. In addition to the bluer-when-brighter trend,
the object also showed a bluer color when it was more active. The observed
variability and its color behaviors are consistent with the shock-in-jet model.Comment: 30 pages, 22 figures, accepted by A
Multicolor photometry of the galaxies in the central region of Abell 2634
An optical photometric observation with the BATC multicolor system is carried
out for the central 56' x 56' region of the nearby cluster of galaxies, Abell
2634. We achieved the spectral energy distributions (SEDs) of 5572 sources
detected down to mag, including 178 previously known galaxies, with
fourteen filters covering a wavelength range from 3600 \AA\ to 10000 \AA. After
excluding the foreground and background galaxies, a sample of 124 known members
is formed for an investigation of the SED properties. Based on the knowledge of
SED properties of member galaxies, we performed the selection of faint galaxies
belonging to Abell 2634. The color-color diagrams are powerful in the
star/galaxy separation, and 359 faint galaxies are selected by their color
features. The technique of photometric redshift and color-magnitude correlation
for the early-type galaxies are applied for these faint galaxies, and a list of
74 faint member galaxies is achieved. Basis on the enlarged sample of member
galaxies, the spatial distribution and color-magnitude relation of the galaxies
in core region of Abell 2634 are discussed. We find a tendency that the color
index dispersion of the early-type members is larger for the outer region,
which might reflect some clues about the environmental effect on the evolution
of galaxies in a cluster.Comment: 35 pages, 21 Postscript figures and tables, LaTeX, using aasms4.st
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