1,933 research outputs found
CaveSeg: Deep Semantic Segmentation and Scene Parsing for Autonomous Underwater Cave Exploration
In this paper, we present CaveSeg - the first visual learning pipeline for
semantic segmentation and scene parsing for AUV navigation inside underwater
caves. We address the problem of scarce annotated training data by preparing a
comprehensive dataset for semantic segmentation of underwater cave scenes. It
contains pixel annotations for important navigation markers (e.g. caveline,
arrows), obstacles (e.g. ground plain and overhead layers), scuba divers, and
open areas for servoing. Through comprehensive benchmark analyses on cave
systems in USA, Mexico, and Spain locations, we demonstrate that robust deep
visual models can be developed based on CaveSeg for fast semantic scene parsing
of underwater cave environments. In particular, we formulate a novel
transformer-based model that is computationally light and offers near real-time
execution in addition to achieving state-of-the-art performance. Finally, we
explore the design choices and implications of semantic segmentation for visual
servoing by AUVs inside underwater caves. The proposed model and benchmark
dataset open up promising opportunities for future research in autonomous
underwater cave exploration and mapping.Comment: submitted for review in ICRA 2024. 10 pages, 9 figure
Evaluation of advanced lift concepts and fuel conservative short-haul aircraft, volume 1
The performance and economics of a twin-engine augmentor wing airplane were evaluated in two phases. Design aspects of the over-the-wing/internally blown flap hybrid, augmentor wing, and mechanical flap aircraft were investigated for 910 m. field length with parametric extension to other field lengths. Fuel savings achievable by application of advanced lift concepts to short-haul aircraft were evaluated and the effect of different field lengths, cruise requirements, and noise levels on fuel consumption and airplane economics at higher fuel prices were determined. Conclusions and recommendations are presented
Evaluation of advanced lift concepts and fuel conservative short-haul aircraft, volume 2
For abstract, see N75-20291
Intraventricular glioneuronal tumor with disseminated lesions at diagnosis - a case report -
A 55-year-old man presented with a large tumor in his lateral ventricles. Magnetic resonance imaging revealed disseminated lesions in the third and fourth ventricles at the time of diagnosis. The patient underwent a partial removal of the tumor in the lateral ventricles. Histologically, the surgical specimens showed glioneuronal differentiation with ganglion or ganglioid cells, Rosenthal fibers, oligodendroglia-like honeycomb appearances, a spongy pattern, perivascular pseudorosettes, and many hyalinized blood vessels. Papillary structure was not observed. The neuronal component showed a moderately high labeling index of Ki-67/MIB-1. We diagnosed this tumor as atypical intraventricular glioneuronal tumor. The disseminated lesions disappeared after chemoradiation therapy with temozolomide, and the residual tumors in the lateral ventricles remained stable for 3 years after the surgery. We discuss the pathological diagnosis, therapy and clinical course with review of the literatures
Ab-initio structural, elastic, and vibrational properties of carbon nanotubes
A study based on ab initio calculations is presented on the estructural,
elastic, and vibrational properties of single-wall carbon nanotubes with
different radii and chiralities. We use SIESTA, an implementation of
pseudopotential-density-functional theory which allows calculations on systems
with a large number of atoms per cell. Different quantities like bond
distances, Young moduli, Poisson ratio and the frequencies of different phonon
branches are monitored versus tube radius. The validity of expectations based
on graphite is explored down to small radii, where some deviations appear
related to the curvature effects. For the phonon spectra, the results are
compared with the predictions of the simple zone-folding approximation. Except
for the known defficiencies of this approximation in the low-frequency
vibrational regions, it offers quite accurate results, even for relatively
small radii.Comment: 13 pages, 7 figures, submitted to Phys. Rev. B (11 Nov. 98
Towards achieving circularity and sustainability in feeds for farmed blue foods
acceptedVersio
One-carbon metabolism in cancer
Cells require one-carbon units for nucleotide synthesis, methylation and reductive metabolism, and these pathways support the high proliferative rate of cancer cells. As such, anti-folates, drugs that target one-carbon metabolism, have long been used in the treatment of cancer. Amino acids, such as serine are a major one-carbon source, and cancer cells are particularly susceptible to deprivation of one-carbon units by serine restriction or inhibition of de novo serine synthesis. Recent work has also begun to decipher the specific pathways and sub-cellular compartments that are important for one-carbon metabolism in cancer cells. In this review we summarise the historical understanding of one-carbon metabolism in cancer, describe the recent findings regarding the generation and usage of one-carbon units and explore possible future therapeutics that could exploit the dependency of cancer cells on one-carbon metabolism
Evidence for the η_b(1S) Meson in Radiative Υ(2S) Decay
We have performed a search for the η_b(1S) meson in the radiative decay of the Υ(2S) resonance using a sample of 91.6 × 10^6 Υ(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E_γ = 609.3^(+4.6)_(-4.5)(stat)±1.9(syst) MeV, corresponding to an η_b(1S) mass of 9394.2^(+4.8)_(-4.9)(stat) ± 2.0(syst) MeV/c^2. The branching fraction for the decay Υ(2S) → γη_b(1S) is determined to be [3.9 ± 1.1(stat)^(+1.1)_(-0.9)(syst)] × 10^(-4). We find the ratio of branching fractions B[Υ(2S) → γη_b(1S)]/B[Υ(3S) → γη_b(1S)]= 0.82 ± 0.24(stat)^(+0.20)_(-0.19)(syst)
Cross Sections for the Reactions e+e- --> K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation Events
We study the processes e+e- --> K+ K- pi+pi-gamma, K+ K- pi0pi0gamma, and K+
K- K+ K-gamma, where the photon is radiated from the initial state. About
84000, 8000, and 4200 fully reconstructed events, respectively, are selected
from 454 fb-1 of BaBar data. The invariant mass of the hadronic final state
defines the \epem center-of-mass energy, so that the K+ K- pi+pi- data can be
compared with direct measurements of the e+e- --> K+ K- pi+pi- reaction. No
direct measurements exist for the e+e- --> K+ K-pi0pi0 or e+e- --> K+ K-K+ K-
reactions, and we present an update of our previous result with doubled
statistics. Studying the structure of these events, we find contributions from
a number of intermediate states, and extract their cross sections. In
particular, we perform a more detailed study of the e+e- --> phi(1020)pipigamma
reaction, and confirm the presence of the Y(2175) resonance in the phi(1020)
f0(980) and K+K-f0(980) modes. In the charmonium region, we observe the J/psi
in all three final states and in several intermediate states, as well as the
psi(2S) in some modes, and measure the corresponding product of branching
fraction and electron width.Comment: 35 pages, 42 figure
Study of Upsilon(3S,2S) -> eta Upsilon(1S) and Upsilon(3S,2S) -> pi+pi- Upsilon(1S) hadronic trasitions
We study the Upsilon(3S,2S)->eta Upsilon(1S) and Upsilon(3S,2S)->pi+pi-
Upsilon(1S) transitions with 122 million Upsilon(3S) and 100 million
Upsilon(2S) mesons collected by the BaBar detector at the PEP-II asymmetric
energy e+e- collider. We measure B[Upsilon(2S)->eta
Upsilon(1S)]=(2.39+/-0.31(stat.)+/-0.14(syst.))10^-4 and Gamma[Upsilon(2S)->eta
Upsilon(1S)]/Gamma[Upsilon(2S)-> pi+pi-
Upsilon(1S)]=(1.35+/-0.17(stat.)+/-0.08(syst.))10^-3. We find no evidence for
Upsilon(3S)->eta Upsilon(1S) and obtain B[Upsilon(3S)->eta Upsilon(1S)]<1.0
10^-4 and Gamma[Upsilon(3S)->eta Upsilon(1S)]/Gamma[Upsilon(3S)->pi+pi-
Upsilon(1S)]<2.3 10^-3 as upper limits at the 90% confidence level. We also
provide improved measurements of the Upsilon(2S) - Upsilon(1S) and Upsilon(3S)
- Upsilon(1S) mass differences, 562.170+/-0.007(stat.)+/-0.088(syst.) MeV/c^2
and 893.813+/-0.015(stat.)+/-0.107(syst.) MeV/c^2 respectively.Comment: 8 pages, 16 encapsulated postscript figures, submitted to Phys.Rev.
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