37 research outputs found
Geometry of quantum evolution in a nonequilibrium environment
We theoretically study the geometric effect of quantum dynamical evolution in
the presence of a nonequilibrium noisy environment. We derive the expression of
the time dependent geometric phase in terms of the dynamical evolution and the
overlap between the time evolved state and initial state. It is shown that the
frequency shift induced by the environmental nonequilibrium feature plays a
crucial role in the geometric phase and evolution path of the quantum dynamics.
The nonequilibrium feature of the environment makes the length of evolution
path becomes longer and reduces the dynamical decoherence and non-Markovian
behavior in the quantum dynamics
A 1.5-Mb continuous endogenous viral region in the arbuscular mycorrhizal fungus Rhizophagus irregularis
Most fungal viruses are RNA viruses, and no double-stranded DNA virus that infects fungi is known to date. A recent study detected DNA polymerase genes that originated from large dsDNA viruses in the genomes of basal fungi, suggestive of the existence of dsDNA viruses capable of infecting fungi. In this study, we searched for viral infection signatures in chromosome-level genome assemblies of the arbuscular mycorrhizal fungus Rhizophagus irregularis. We identified a continuous 1.5-Mb putative viral region on a chromosome in R. irregularis strain 4401. Phylogenetic analyses revealed that the viral region is related to viruses in the family Asfarviridae of the phylum Nucleocytoviricota. This viral region was absent in the genomes of four other R. irregularis strains and had fewer signals of fungal transposable elements than the other genomic regions, suggesting a recent and single insertion of a large dsDNA viral genome in the genome of this fungal strain. We also incidentally identified viral-like sequences in the genome assembly of the sea slug Elysia marginata that are evolutionally close to the 1.5-Mb putative viral region. In conclusion, our findings provide strong evidence of the recent infection of the fungus by a dsDNA virus
SoccerNet 2023 Challenges Results
peer reviewedThe SoccerNet 2023 challenges were the third annual video understanding
challenges organized by the SoccerNet team. For this third edition, the
challenges were composed of seven vision-based tasks split into three main
themes. The first theme, broadcast video understanding, is composed of three
high-level tasks related to describing events occurring in the video
broadcasts: (1) action spotting, focusing on retrieving all timestamps related
to global actions in soccer, (2) ball action spotting, focusing on retrieving
all timestamps related to the soccer ball change of state, and (3) dense video
captioning, focusing on describing the broadcast with natural language and
anchored timestamps. The second theme, field understanding, relates to the
single task of (4) camera calibration, focusing on retrieving the intrinsic and
extrinsic camera parameters from images. The third and last theme, player
understanding, is composed of three low-level tasks related to extracting
information about the players: (5) re-identification, focusing on retrieving
the same players across multiple views, (6) multiple object tracking, focusing
on tracking players and the ball through unedited video streams, and (7) jersey
number recognition, focusing on recognizing the jersey number of players from
tracklets. Compared to the previous editions of the SoccerNet challenges, tasks
(2-3-7) are novel, including new annotations and data, task (4) was enhanced
with more data and annotations, and task (6) now focuses on end-to-end
approaches. More information on the tasks, challenges, and leaderboards are
available on https://www.soccer-net.org. Baselines and development kits can be
found on https://github.com/SoccerNet
Anisotropic surroundings effects on photo absorption of partially embedded Au nanospheroids in silica glass substrate
The influence of a directly adjacent or an anisotropic surrounding medium alters the plasmonic properties of a nanoparticle because it provides a mechanism for symmetry breaking of the scattering. Given the success of ion irradiation induced embedment of rigid metallic nanospheroids into amorphous substrate, it is possible to examine the effect of the silica glass substrate on the plasmonic properties of these embedded nanospheroids. In this work presented here, discrete dipole approximation (DDA) calculations for the Au nanospheroids' optical properties were performed based on 3-dimensional (3D) configuration extracted from planar SEM micrographs and cross-sectional TEM micrographs of the Au nanospheroids partially embedded in the silica glass, and the well-matched simulations with respect to the experimental measurements could demonstrate the dielectric constant at the near surface of silica glass decreased after Ar-ion irradiation
Ion irradiation synthesis of Ag-Au bimetallic nanospheroids in SiO2 glass substrate with tunable surface plasmon resonance frequency
Ag-Au bimetallic nanospheroids with tunable localized surface plasmon resonance (LSPR) were synthesized by 100 keV Ar-ion irradiation of 30 nm Ag-Au bimetallic films deposited on SiO2 glass substrates. A shift of the LSPR peaks toward shorter wavelengths was observed up to an irradiation fluence of 1.0 x 10(17) cm(-2), and then shifted toward the longer wavelength because of the increase of fragment volume under ion irradiation. Further control of LSPR frequency over a wider range was realized by modifying the chemical components. The resulting LSPR frequencies lie between that of the pure components, and an approximate linear shift of the LSPR toward the longer wavelength with the Au concentration was achieved, which is in good agreement with the theoretical calculations based on Gans theory. In addition, the surface morphology and compositions were examined with a scanning electron microscope equipped with an energy dispersive spectrometer, and microstructural characterizations were performed using a transmission electron microscope. The formation of isolated photosensitive Ag-Au nanospheroids with a FCC structure partially embedded in the SiO2 substrate was confirmed, which has a potential application in solid-state devices. (C) 2013 AIP Publishing LLC
Shift of localized surface plasmon resonance by Ar-ion irradiation of Ag–Au bimetallic films deposited on Al2O3 single crystals
Effects of Ar-ion induced surface nanostructuring were studied using 100 keV Ar-ion irradiation of 30 nm Ag–Au bimetallic films deposited on Al2O3 single crystals, under irradiation fluences ranging from 5.0 1015 cm 2 to 6.3 1016 cm 2. Scanning electron microscope was used to study the ion-beaminduced surface nanostructuring. As the irradiation fluence increased, dewetting of the bimetallic films on the Al2O3 substrate was observed, and formation of isolated Ag–Au nanostructures sustained on the substrate were obtained. Next, thermal annealing was performed under high vacuum at 1073 K for 2 h; a layer of photosensitive Ag–Au alloy nanoballs partially embedded in the Al2O3 substrate was obtained when higher fluence irradiation (>3.8 1016 cm 2) was used. The microstructures of the nanoballs were investigated using a transmission electron microscope, and the nanoballs were found to be single crystals with a FCC structure. In addition, photoabsorption spectra were measured, and localized surface plasmon resonance peaks were observed. With increase in the irradiation fluence, the size of the Ag–Au nanoballs on the substrate decreased, and a blue-shift of the LSPR peaks was observed. Further control of the LSPR frequency over a wide range was achieved by modifying the chemical components, and a red-shift of the LSPR peaks was observed as the Au concentration increased. In summary, ion irradiation is an effective approach toward surface nanostructuring, and the nanocomposites obtained have potential applications in optical devices
Plasmonic surface nanostructuring of Au-dots@SiO2 via laser-irradiation induced dewetting
The in situ observation of Au dot formation and the self-assembly dynamics of Au nanoparticles (NPs) was successfully demonstrated via dewetting of Au thin films on SiO2 glass substrates under nano-second pulsed laser irradiation using a multi-quantum beam high-voltage electron microscope. Moreover, using electron energy-loss spectroscopy (EELS) performed in a scanning transmission electron microscope (STEM), the plasmonic properties of the formed Au/SiO2 nanostructure were analyzed to demonstrate its validity in advanced optical devices. The uniformly distributed Au NPs evolved into a dot alignment through movement and coalescence processes was demonstrated in this in situ observation. We carried out the plasmon-loss images of the plan view and the cross-section of the Au/SiO2 nanostructures were obtained at the plasmon-loss peak energy for investigate the three-dimensional distribution of surface plasmon. Furthermore, discrete-dipole approximation (DDA) calculations were used to simulate the plasmonic properties, such as the surface plasmon resonance and the surface plasmon field distribution, of isolated single Au/SiO2 nanostructures. This STEM-EELS-acquired surface plasmon map of the cross-sectional sample is in excellent agreement with the DDA calculations. This results demonstrated the influence of the contact condition between Au NP and SiO2 glass on the plasmonic properties, and may improve the technology for developing advanced optical devices
Effects of ion and nanosecond-pulsed laser co-irradiation on the surface nanostructure of Au thin films on SiO2 glass substrates
Ion irradiation and short-pulsed laser irradiation can be used to form nanostructures on the surfaces of substrates. This work investigates the synergistic effects of ion and nanosecond-pulsed laser co-irradiation on surface nanostructuring of Au thin films deposited under vacuum on SiO2 glass substrates. Gold nanoparticles are randomly formed on the surface of the substrate after nanosecond-pulsed laser irradiation under vacuum at a wavelength of 532 nm with a repetition rate of 10 Hz and laser energy density of 0.124 kJ/m(2). Gold nanoparticles are also randomly formed on the substrate after 100-keV Ar+ ion irradiation at doses of up to 3.8 x 10(15) ions/cm(2), and nearly all of these nanoparticles are fully embedded in the substrate. With increasing ion irradiation dose (number of incident laser pulses), the mean diameter of the Au nanoparticles decreases (increases). However, Au nanoparticles are only formed in a periodic surface arrangement after co-irradiation with 6000 laser pulses and 3.8 x 10(15) ions/cm(2). The periodic distance is similar to 540 nm, which is close to the wavelength of the nanosecond-pulsed laser, and the mean diameter of the Au nanoparticles remains at similar to 20 nm with a relatively narrow distribution. The photoabsorption peaks of the ion-or nanosecond-pulsed laser-irradiated samples clearly correspond to the mean diameter of Au nanoparticles. Conversely, the photoabsorption peaks for the co-irradiated samples do not depend on the mean nanoparticle diameter. This lack of dependence is likely caused by the periodic nanostructure formed on the surface by the synergistic effects of co-irradiation
Effects of nanosecond-pulsed laser irradiation on nanostructure formation on the surface of thin Au films on Si02 glass substrates
In this study, we investigated nanostructure formations on the surface of Au thin films deposited on SiO2 glass substrates after nanosecond-pulsed laser irradiation, also the correlation between the nanostructures parameters and the photoabsorption peak. Spherical Au nanoparticle/SiO2 glass nanocomposites were formed on the surface of the Au thin films deposited on the SiO2 glass substrates after nanosecondpulsed laser irradiation in air with a wavelength of 532 nm at a repetition rate of 2 Hz and a laser energy density of 0.7 kJ/m(2). Au nanoparticles were periodically arranged on the substrates under laser irradiation perpendicular to the direction of the electrical field vector of the laser light, the average diameter of Au nanoparticles was increased from 59.3 to 67.4 nm and the average distance of the laser induced periodical structure was decreased from 1.3 to 1.0 mu m as the number of laser pulses increased from 1000 to 1500. After 2000 pulses irradiation, an additional laser irradiation induced periodical structure was formed in the direction parallel to the electrical field vector of the laser. The average periodicity of this nanostructure perpendicular to the initial nanostructure was 560 nm, which is close to the wavelength of the nanosecond-pulsed laser used in this study. The average diameter of these Au nanoparticles is 41.9 nm which is smaller than that of the Au nanoparticles formed after 1000 pulses irradiation. Au nanoparticles were generally dispersed on the surface while some were embedded in the substrate. After 1500 pulses irradiation, the diameter of the Au nanoparticles on the Au(30 nm)/SiO2(0.8 mm) is relatively larger than that of the Au nanoparticles on the Au(20 nm)/SiO2(0.1 mm). Each of laser irradiated sample showed an own photoabsorption peak clearly in this study. Furthermore, effects of the average diameter of the Au nanoparticles on the photoabsorption peak are discussed