878 research outputs found
Cut-rose production in response to planting density in two contrasting cultivars
Growing in lower planting density, rose plants produce more assimilates, which can be used to produce more and/or heavier flowering shoots. The effect of planting density was investigated during a period including the first five flowering flushes of a young crop. In a heated greenhouse two cut-rose cultivars were grown under bent canopy management. ‘Akito’ on own-roots and ‘Ilios’ on ‘Natal Briar’ rootstock were planted with densities of 8 and 4 plants per m2. Starting at the end of June 2007, flowering shoots were harvested over a time span of eight months. Based on ‘flowering flushes’, times of high harvest rate, the harvesting time span could be divided into five consecutive periods, each including one flush. The cultivars showed contrasting responses to planting density. In the first three periods the response in ‘Ilios’ was extraordinary, because at low density plants did not produce more flowering shoots, as would be expected. However, the response in shoot fresh weight was larger for ‘Ilios’ than for ‘Akito’, 35% compared to 21% over the entire study period. The results imply that there was a genetic difference in the effect of assimilate availability and/or local light environment. During the first three periods, these factors can not have influenced shoot number in ‘Ilios’, while they did in ‘Akito’. It is suggested that decreases of assimilate availability in winter caused the shoot number response to emerge for ‘Ilios’ later on
Deep Compact Person Re-Identification with Distractor Synthesis via Guided DC-GANs
We present a dual-stream CNN that learns both appearance and facial features in tandem from still images and, after feature fusion, infers person identities. We then describe an alternative architecture of a single, lightweight ID-CondenseNet where a face detector-guided DC-GAN is used to generate distractor person images for enhanced training. For evaluation, we test both architectures on FLIMA, a new extension of an existing person re-identification dataset with added frame-by-frame annotations of face presence. Although the dual-stream CNN can outperform the CondenseNet approach on FLIMA, we show that the latter surpasses all state-of-the-art architectures in top-1 ranking performance when applied to the largest existing person re-identification dataset, MSMT17. We conclude that whilst re-identification performance is highly sensitive to the structure of datasets, distractor augmentation and network compression have a role to play for enhancing performance characteristics for larger scale applications
Semantically selective augmentation for deep compact person re-identification
We present a deep person re-identification approach that combines semantically selective, deep data augmentation with clustering-based network compression to generate high performance, light and fast inference networks. In particular, we propose to augment limited training data via sampling from a deep convolutional generative adversarial network (DCGAN), whose discriminator is constrained by a semantic classifier to explicitly control the domain specificity of the generation process. Thereby, we encode information in the classifier network which can be utilized to steer adversarial synthesis, and which fuels our CondenseNet ID-network training. We provide a quantitative and qualitative analysis of the approach and its variants on a number of datasets, obtaining results that outperform the state-of-the-art on the LIMA dataset for long-term monitoring in indoor living spaces
Electron--Electron Scattering in Quantum Wires and it's Possible Suppression due to Spin Effects
A microscopic picture of electron-electron pair scattering in single mode
quantum wires is introduced which includes electron spin. A new source of
`excess' noise for hot carriers is presented. We show that zero magnetic field
`spin' splitting in quantum wires can lead to a dramatic `spin'-subband
dependence of electron--electron scattering, including the possibility of
strong suppression. As a consequence extremely long electron coherence lengths
and new spin-related phenomena are predicted. Since electron bands in III-V
semiconductor quantum wires are in general spin-split in zero applied magnetic
field, these new transport effects are of general importance.Comment: 11 pages, LaTeX and APS-RevteX 2, Rep.No. GF66,Figures from author,
Physical Review Letters, scheduled for 7 June 199
Online quality assessment of human movement from skeleton data
We propose a general method for online estimation of the quality of movement from Kinect
skeleton data. A robust non-linear manifold learning technique is used to reduce the
dimensionality of the noisy skeleton data. Then, a statistical model of normal movement is
built from observations of healthy subjects, and the level of matching of new observations
with this model is computed on a frame-by-frame basis following Markovian assumptions.
The proposed method is validated on the assessment of gait on stairs
MOIRCS Deep Survey. VIII. Evolution of Star Formation Activity as a Function of Stellar Mass in Galaxies since z~3
We study the evolution of star formation activity of galaxies at 0.5<z<3.5 as
a function of stellar mass, using very deep NIR data taken with Multi-Object
Infrared Camera and Spectrograph (MOIRCS) on the Subaru telescope in the
GOODS-North region. The NIR imaging data reach K ~ 23-24 Vega magnitude and
they allow us to construct a nearly stellar mass-limited sample down to ~
10^{9.5-10} Msun even at z~3. We estimated star formation rates (SFRs) of the
sample with two indicators, namely, the Spitzer/MIPS 24um flux and the
rest-frame 2800A luminosity. The SFR distribution at a fixed Mstar shifts to
higher values with increasing redshift at 0.5<z<3.5. More massive galaxies show
stronger evolution of SFR at z>~1. We found galaxies at 2.5<z<3.5 show a
bimodality in their SSFR distribution, which can be divided into two
populations by a constant SSFR of ~2 Gyr^{-1}. Galaxies in the low-SSFR group
have SSFRs of ~ 0.5-1.0 Gyr^{-1}, while the high-SSFR population shows ~10
Gyr^{-1}. The cosmic SFRD is dominated by galaxies with Mstar = 10^{10-11} Msun
at 0.5<z<3.5, while the contribution of massive galaxies with Mstar =
10^{11-11.5} Msun shows a strong evolution at z>1 and becomes significant at
z~3, especially in the case with the SFR based on MIPS 24um. In galaxies with
Mstar = 10^{10-11.5} Msun, those with a relatively narrow range of SSFR (<~1
dex) dominates the cosmic SFRD at 0.5<z<3.5. The SSFR of galaxies which
dominate the SFRD systematically increases with redshift. At 2.5<z<3.5, the
high-SSFR population, which is relatively small in number, dominates the SFRD.
Major star formation in the universe at higher redshift seems to be associated
with a more rapid growth of stellar mass of galaxies.Comment: 16 pages, 13 figures, accepted for publication in Ap
Spin degree of freedom in two dimensional exciton condensates
We present a theoretical analysis of a spin-dependent multicomponent
condensate in two dimensions. The case of a condensate of resonantly
photoexcited excitons having two different spin orientations is studied in
detail. The energy and the chemical potentials of this system depend strongly
on the spin polarization . When electrons and holes are located in two
different planes, the condensate can be either totally spin polarized or spin
unpolarized, a property that is measurable. The phase diagram in terms of the
total density and electron-hole separation is discussed.Comment: 4 pages, 3 figures, Accepted for publication in Physical Review
Letter
Electric-Field Tuning of Spin-Dependent Exciton-Exciton Interactions in Coupled Quantum Wells
We have shown experimentally that an electric field decreases the energy
separation between the two components of a dense spin-polarized exciton gas in
a coupled double quantum well, from a maximum splitting of meV to
zero, at a field of 35 kV/cm. This decrease, due to the field-induced
deformation of the exciton wavefunction, is explained by an existing
calculation of the change in the spin-dependent exciton-exciton interaction
with the electron-hole separation. However, a new theory that considers the
modification of screening with that separation is needed to account for the
observed dependence on excitation power of the individual energies of the two
exciton components.Comment: 5 pages, 4 eps figures, RevTeX, Physical Review Letters (in press
Achromatic late-time variability in thermonuclear X-ray bursts - an accretion disk disrupted by a nova-like shell?
An unusual Eddington-limited thermonuclear X-ray burst was detected from the
accreting neutron star in 2S 0918-549 with the Rossi X-ray Timing Explorer. The
burst commenced with a brief (40 ms) precursor and maintained near-Eddington
fluxes during the initial 77 s. These characteristics are indicative of a
nova-like expulsion of a shell from the neutron star surface. Starting 122 s
into the burst, the burst shows strong (87 +/- 1% peak-to-peak amplitude)
achromatic fluctuations for 60 s. We speculate that the fluctuations are due to
Thompson scattering by fully-ionized inhomogeneities in a resettling accretion
disk that was disrupted by the effects of super-Eddington fluxes. An expanding
shell may be the necessary prerequisite for the fluctuations.Comment: 7 pages, 4 figures. Submitted to A&
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