28,521 research outputs found
Possible and Molecular states in a chiral quark model
We perform a systematic study of the bound state problem of and
systems by using effective interaction in our chiral quark model.
Our results show that both the interactions of and states
are attractive, which consequently result in
and bound states.Comment: arXiv admin note: substantial text overlap with arXiv:1204.395
Harmonizer: Learning to Perform White-Box Image and Video Harmonization
Recent works on image harmonization solve the problem as a pixel-wise image
translation task via large autoencoders. They have unsatisfactory performances
and slow inference speeds when dealing with high-resolution images. In this
work, we observe that adjusting the input arguments of basic image filters,
e.g., brightness and contrast, is sufficient for humans to produce realistic
images from the composite ones. Hence, we frame image harmonization as an
image-level regression problem to learn the arguments of the filters that
humans use for the task. We present a Harmonizer framework for image
harmonization. Unlike prior methods that are based on black-box autoencoders,
Harmonizer contains a neural network for filter argument prediction and several
white-box filters (based on the predicted arguments) for image harmonization.
We also introduce a cascade regressor and a dynamic loss strategy for
Harmonizer to learn filter arguments more stably and precisely. Since our
network only outputs image-level arguments and the filters we used are
efficient, Harmonizer is much lighter and faster than existing methods.
Comprehensive experiments demonstrate that Harmonizer surpasses existing
methods notably, especially with high-resolution inputs. Finally, we apply
Harmonizer to video harmonization, which achieves consistent results across
frames and 56 fps at 1080P resolution. Code and models are available at:
https://github.com/ZHKKKe/Harmonizer
Are Relational Contracting Approaches Applicable to Public Projects in China?
Rising complexities in construction projects management has boosted the importance of relational contracting (RC) in the field. RC is based on recognition of mutual benefits and win-win scenarios gained through more cooperative relationships between contracting parties. There have been a range of RC initiatives across many countries towards deeper collaborative relationships; however, such formal RC approaches are not yet well established in China. In this paper, the feasibility of implementing RC in the China’s public construction projects is investigated. The results indicate that RC is highly feasible for implementation in China due to its theoretical benefits, its alignment to Chinese culture, and its behaviors in past public construction projects. Three strategies for facilitating the implementation of RC in China are proposed
Factors influencing the private involvement in Urban rail public-private partnership projects in China
© 2017 by the author(s). Private investors have been encouraged to participate in the development and operation of urban rail projects in China through Public-Private Partnerships (PPPs), given the fact that subnational governments are suffering from urgent development demands and severe fiscal pressure. However, there is no formal assessment to determine the private involvement in a PPP project. This problem is particularly critical in the sector of urban rail, in which the huge investment cannot rely on the private sector alone. This study hence aimed to uncover and identify the influencing factors. Multiple research methods, including content analysis, case study and focus group discussion were adopted to achieve the research purpose. Seven types of influencing factors were identified, including project financial model, government fiscal commitment, risk allocation, public accountability, efficiency considerations, policy and regulations, and organisational marketing strategies. The findings add to the current knowledge base by uncovering the drivers behind private involvement in a PPP project. They are also beneficial for industry practitioners as a basis/checklist to determine the private involvement
Specific Resistance of Pd/Ir Interfaces
From measurements of the current-perpendicular-to-plane (CPP) total specific
resistance (AR = area times resistance) of sputtered Pd/Ir multilayers, we
derive the interface specific resistance, 2AR(Pd/Ir) = 1.02 +/- 0.06 fOhmm^2,
for this metal pair with closely similar lattice parameters. Assuming a single
fcc crystal structure with the average lattice parameter, no-free-parameter
calculations, including only spd orbitals, give for perfect interfaces,
2AR(Pd/Ir)(Perf) = 1.21 +/-0.1 fOhmm^2, and for interfaces composed of two
monolayers of a random 50%-50% alloy, 2AR(Pd/Ir)(50/50) = 1.22 +/- 0.1 fOhmm^2.
Within mutual uncertainties, these values fall just outside the range of the
experimental value. Updating to add f-orbitals gives 2AR(Pd/Ir)(Perf) = 1.10
+/- 0.1 fOhmm^2 and 2AR(Pd/Ir)(50-50) = 1.13 +/- 0.1 fOhmm^2, values now
compatible with the experimental one. We also update, with f-orbitals,
calculations for other pairsComment: 3 pages, 1 figure, in press in Applied Physics Letter
On Silicon Carbide Grains as the Carrier of the 21 Micron Emission Feature in Post-Asymptotic Giant Branch Stars
The mysterious 21mu emission feature seen in 12 proto-planetary nebulae
(PPNe) remains unidentified since its first detection in 1989. Over a dozen of
candidate materials have been proposed within the past decade, but none of them
has received general acceptance. Very recently, silicon carbide (SiC) grains
with impurities were suggested to be the carrier of this enigmatic feature,
based on recent laboratory data that doped SiC grains exhibit a resonance at
\~21mu. This proposal gains strength from the fact that SiC is a common dust
species in carbon-rich circumstellar envelopes. However, SiC dust has a strong
vibrational band at ~11.3mu. We show in this Letter that in order to be
consistent with the observed flux ratios of the 11.3mu feature to the 21mu
feature, the band strength of the 21mu resonance has to be very strong, too
strong to be consistent with current laboratory measurements. But this does not
yet readily rule out the SiC hypothesis since recent experimental results have
demonstrated that the 21mu resonance of doped SiC becomes stronger as the C
impurity increases. Further laboratory measurements of SiC dust with high
fractions of C impurity are urgently needed to test the hypothesis of SiC as
the carrier of the 21mu feature.Comment: 14 pages, 3 figures, accepted for publication in ApJ
A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris
The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous ldquobridgesrdquo. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections
Absorbate-Induced Piezochromism in a Porous Molecular Crystal
Atmospherically stable porous frameworks
and materials are interesting
for heterogeneous solid–gas applications. One motivation is
the direct and selective uptake of pollutant/hazardous gases, where
the material produces a measurable response in the presence of the
analyte. In this report, we present a combined experimental and theoretical
rationalization for the piezochromic response of a robust and porous
molecular crystal built from an extensively fluorinated trispyrazole.
The electronic response of the material is directly determined by
analyte uptake, which provokes a subtle lattice contraction and an
observable bathochromic shift in the optical absorption onset. Selectivity
for fluorinated absorbates is demonstrated, and toluene is also found
to crystallize within the pore. Furthermore, we demonstrate the application
of electronic structure calculations to predict a physicochemical
response, providing the foundations for the design of electronically
tunable porous solids with the chemical properties required for development
of novel gas-uptake media
Slow relaxation of piezoelectric response in CdZnTe ferroelectric semiconductor single crystals
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