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Infrared emission bands and thermal effects for 440-nm-emitting GaN-based laser diodes
Broad emission bands due to defects in (In,Ga,Al)N laser diodes operating at 440 nm are investigated using continuous-wave and pulsed currents. In addition to known yellow-green and short-wave infrared bands, defect emissions were observed even in the medium-wave infrared range. A separation from thermal radiation is possible. When using pulsed currents, a super-linearly increasing emission occurs at ∼1150 nm, which could be attributed to amplified spontaneous emission mainly due to the electroluminescence of deep defects in the optically active region. These results may be useful in interpreting the output power bottleneck of GaN-based lasers compared to mature GaAs-based lasers. © 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/1.514380
Lattice Dynamics and the High Pressure Equation of State of Au
Elastic constants and zone-boundary phonon frequencies of gold are calculated
by total energy electronic structure methods to twofold compression. A
generalized force constant model is used to interpolate throughout the
Brillouin zone and evaluate moments of the phonon distribution. The moments are
used to calculate the volume dependence of the Gruneisen parameter in the fcc
solid. Using these results with ultrasonic and shock data, we formulate the
complete free energy for solid Au. This free energy is given as a set of closed
form expressions, which are valid to compressions of at least V/V_0 = 0.65 and
temperatures up to melting. Beyond this density, the Hugoniot enters the
solid-liquid mixed phase region. Effects of shock melting on the Hugoniot are
discussed within an approximate model. We compare with proposed standards for
the equation of state to pressures of ~200 GPa. Our result for the room
temperature isotherm is in very good agreement with an earlier standard of
Heinz and Jeanloz.Comment: 13 pages, 8 figures. Accepted by Phys. Rev.
Effect of shading on biomass and N mass partitioning in paddy rice seedlings through allometric analysis
An allometric analysis of biomass and N mass allocation of rice (Oryza sativa L.) seedlings under non-shaded (100% of full sunlight) and shaded (30% of full sunlight) treatments were conducted. The allometric slopes and the intercepts were estimated using standardized major axis regression. Results indicated that biomass was preferentially allocated to stems during plant ontogeny, and leaves and roots were isometric when rice seedlings were not shaded. Under shade, however, more biomass was allocated to leaves and stems. N mass allocation was also altered by shading in that more N mass was allocated to the aerial shoots, and plants accumulated less N mass when shaded. Our study revealed that both biomass and N mass were in accordance with the optimal partitioning theory
Exploring morphological correlations among H2CO, 12CO, MSX and continuum mappings
There are relatively few H2CO mappings of large-area giant molecular cloud
(GMCs). H2CO absorption lines are good tracers for low-temperature molecular
clouds towards star formation regions. Thus, the aim of the study was to
identify H2CO distributions in ambient molecular clouds. We investigated
morphologic relations among 6-cm continuum brightness temperature (CBT) data
and H2CO (111-110; Nanshan 25-m radio telescope), 12CO (1--0; 1.2-m CfA
telescope) and midcourse space experiment (MSX) data, and considered the impact
of background components on foreground clouds. We report simultaneous 6-cm H2CO
absorption lines and H110\alpha radio recombination line observations and give
several large-area mappings at 4.8 GHz toward W49 (50'\times50'), W3
(70'\times90'), DR21/W75 (60'\times90') and NGC2024/NGC2023 (50'\times100')
GMCs. By superimposing H2CO and 12CO contours onto the MSX color map, we can
compare correlations. The resolution for H2CO, 12CO and MSX data was about 10',
8' and 18.3", respectively. Comparison of H2CO and 12CO contours, 8.28-\mu m
MSX colorscale and CBT data revealed great morphological correlation in the
large area, although there are some discrepancies between 12CO and H2CO peaks
in small areas. The NGC2024/NGC2023 GMC is a large area of HII regions with a
high CBT, but a H2CO cloud to the north is possible against the cosmic
microwave background. A statistical diagram shows that 85.21% of H2CO
absorption lines are distributed in the intensity range from -1.0 to 0 Jy and
the \Delta V range from 1.206 to 5 km/s.Comment: 18 pages, 22 figures, 5 tables. Accepted to be published in
Astrophysics and Space Scienc
KELT-3b: A Hot Jupiter Transiting A V=9.8 Late-F Star
We report the discovery of KELT-3b, a moderately inflated transiting hot Jupiter with a mass of 1.477(-0.067)(+0.066) M-J, radius of 1.345 +/- 0.072 R-J, and an orbital period of 2.7033904 +/- 0.000010 days. The host star, KELT-3, is a V = 9.8 late F star with M-* = 1.278(-0.061)(+0.063) M-circle dot, R-* = 1.472(-0.067)(+0.065) R-circle dot, T-eff = 6306(-49)(+50) K, log(g) = 4.209(-0.031)(+0.033), and [Fe/H] = 0.044(-0.082)(+0.080), and has a likely proper motion companion. KELT-3b is the third transiting exoplanet discovered by the KELT survey, and is orbiting one of the 20 brightest known transiting planet host stars, making it a promising candidate for detailed characterization studies. Although we infer that KELT-3 is significantly evolved, a preliminary analysis of the stellar and orbital evolution of the system suggests that the planet has likely always received a level of incident flux above the empirically identified threshold for radius inflation suggested by Demory & Seager
Zero-bias conductance peak splitting due to multiband effect in tunneling spectroscopy
We study how the multiplicity of the Fermi surface affects the zero-bias peak
in conductance spectra of tunneling spectroscopy. As case studies, we consider
models for organic superconductors -(BEDT-TTF)Cu(NCS) and
(TMTSF)ClO. We find that multiplicity of the Fermi surfaces can lead to
a splitting of the zero-bias conductance peak (ZBCP). We propose that the
presence/absence of the ZBCP splitting is used as a probe to distinguish the
pairing symmetry in -(BEDT-TTF)Cu(NCS).Comment: 7 pages, 7 figure
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
Theory of charge transport in diffusive normal metal / unconventional singlet superconductor contacts
We analyze the transport properties of contacts between unconventional
superconductor and normal diffusive metal in the framework of the extended
circuit theory. We obtain a general boundary condition for the Keldysh-Nambu
Green's functions at the interface that is valid for arbitrary transparencies
of the interface. This allows us to investigate the voltage-dependent
conductance (conductance spectrum) of a diffusive normal metal (DN)/
unconventional singlet superconductor junction in both ballistic and diffusive
cases. For d-wave superconductor, we calculate conductance spectra numerically
for different orientations of the junctions, resistances, Thouless energies in
DN, and transparencies of the interface. We demonstrate that conductance
spectra exhibit a variety of features including a -shaped gap-like
structure, zero bias conductance peak (ZBCP) and zero bias conductance dip
(ZBCD). We show that two distinct mechanisms: (i) coherent Andreev reflection
(CAR) in DN and (ii) formation of midgap Andreev bound state (MABS) at the
interface of d-wave superconductors, are responsible for ZBCP, their relative
importance being dependent on the angle between the interface normal
and the crystal axis of d-wave superconductors. For , the ZBCP is due
to CAR in the junctions of low transparency with small Thouless energies, this
is similar to the case of diffusive normal metal / insulator /s-wave
superconductor junctions. With increase of from zero to , the
MABS contribution to ZBCP becomes more prominent and the effect of CAR is
gradually suppressed. Such complex spectral features shall be observable in
conductance spectra of realistic high- junctions at very low temperature
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
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