1,144 research outputs found
Text to 3D Scene Generation with Rich Lexical Grounding
The ability to map descriptions of scenes to 3D geometric representations has
many applications in areas such as art, education, and robotics. However, prior
work on the text to 3D scene generation task has used manually specified object
categories and language that identifies them. We introduce a dataset of 3D
scenes annotated with natural language descriptions and learn from this data
how to ground textual descriptions to physical objects. Our method successfully
grounds a variety of lexical terms to concrete referents, and we show
quantitatively that our method improves 3D scene generation over previous work
using purely rule-based methods. We evaluate the fidelity and plausibility of
3D scenes generated with our grounding approach through human judgments. To
ease evaluation on this task, we also introduce an automated metric that
strongly correlates with human judgments.Comment: 10 pages, 7 figures, 3 tables. To appear in ACL-IJCNLP 201
Geometry-induced phase transition in fluids: capillary prewetting
We report a new first-order phase transition preceding capillary condensation
and corresponding to the discontinuous formation of a curved liquid meniscus.
Using a mean-field microscopic approach based on the density functional theory
we compute the complete phase diagram of a prototypical two-dimensional system
exhibiting capillary condensation, namely that of a fluid with long-ranged
dispersion intermolecular forces which is spatially confined by a substrate
forming a semi-infinite rectangular pore exerting long-ranged dispersion forces
on the fluid. In the T-mu plane the phase line of the new transition is
tangential to the capillary condensation line at the capillary wetting
temperature, Tcw. The surface phase behavior of the system maps to planar
wetting with the phase line of the new transition, termed capillary prewetting,
mapping to the planar prewetting line. If capillary condensation is approached
isothermally with T>Tcw, the meniscus forms at the capping wall and unbinds
continuously, making capillary condensation a second-order phenomenon. We
compute the corresponding critical exponent for the divergence of adsorption.Comment: 5 pages, 4 figures, 5 movie
Slip or not slip? A methodical examination of the interface formation model using two-dimensional droplet spreading on a horizontal planar substrate as a prototype system
We consider the spreading of a thin two-dimensional droplet on a planar
substrate as a prototype system to compare the contemporary model for contact
line motion based on interface formation of Shikhmurzaev [Int. J. Multiphas.
Flow 19, 589 (1993)], to the more commonly used continuum fluid dynamical
equations augmented with the Navier-slip condition. Considering quasistatic
droplet evolution and using the method of matched asymptotics, we find that the
evolution of the droplet radius using the interface formation model reduces to
an equivalent expression for a slip model, where the prescribed microscopic
dynamic contact angle has a velocity dependent correction to its static value.
This result is found for both the original interface formation model
formulation and for a more recent version, where mass transfer from bulk to
surface layers is accounted for through the boundary conditions. Various
features of the model, such as the pressure behaviour and rolling motion at the
contact line, and their relevance, are also considered in the prototype system
we adopt.Comment: 45 pages, 18 figure
Large-scale benchmarks of the Time-Warp/Graph-Theoretical Kinetic Monte Carlo approach for distributed on-lattice simulations of catalytic kinetics
We extend the work of Ravipati et al.[Comput. Phys. Commun., 2022, 270, 108148] in benchmarking the performance of large-scale, distributed, on-lattice kinetic Monte Carlo (KMC) simulations. Our software package, Zacros, employs a graph-theoretical approach to KMC, coupled with the Time-Warp algorithm for parallel discrete event simulations. The lattice is divided into equal subdomains, each assigned to a single processor; the cornerstone of the Time-Warp algorithm is the state queue, to which snapshots of the KMC (lattice) state are saved regularly, enabling historical KMC information to be corrected when conflicts occur at the subdomain boundaries. Focusing on three model systems, we highlight the key Time-Warp parameters that can be tuned to optimise KMC performance. The frequency of state saving, controlled by the state saving interval, δsnap, is shown to have the largest effect on performance, which favours balancing the overhead of re-simulating KMC history with that of writing state snapshots to memory. Also important is the global virtual time (GVT) computation interval, ΔτGVT, which has little direct effect on the progress of the simulation but controls how often the state queue memory can be freed up. We find that a vector data structure is, in general, more favourable than a linked list for storing the state queue, due to the reduced time required for allocating and de-allocating memory. These findings will guide users in maximising the efficiency of Zacros or other distributed KMC software, which is a vital step towards realising accurate, meso-scale simulations of heterogeneous catalysis
Seasonal dynamics of native and invasive Halophila stipulacea populations—A case study from the northern Gulf of Aqaba and the eastern Mediterranean Sea
No embargo required, pre-print. Full version requires 24 month embarg
GeoTriples: a Tool for Publishing Geospatial Data as RDF Graphs Using R2RML Mappings
In this paper we present the tool GeoTriples that allows the transformation of Earth Observation data and geospatial data into RDF graphs, by using and extending the R2RML mapping language to be able to deal with the specificities of geospatial data. GeoTriples is a semi-automated tool that transforms geospatial information into RDF following the state of the art vocabularies like GeoSPARQL and stSPARQL, but at the same time it is not tightly coupled to a specific vocabulary
Hexokinase inhibits flux of fluorescently labeled ATP through mitochondrial outer membrane porin
AbstractMitochondrial function requires maintaining metabolite fluxes across the mitochondrial outer membrane, which is mediated primarily by the voltage dependent anion channel (VDAC). We applied fluorescence correlation spectroscopy (FCS) to study regulation of the VDAC functional state by monitoring distribution of fluorescently labeled ATP (BODIPY-FL-ATP) in isolated intact rat liver and heart mitochondria. Addition of mitochondria to BODIPY-FL-ATP solution resulted in accumulation of the fluorescent probe in these organelles. The addition of hexokinase II (HKII) isolated from rat heart led to a decrease in the BODIPY-FL-ATP accumulation, while a 15-residue peptide corresponding to the N-terminal domain of hexokinase did not produce this effect. Therefore, the hexokinase-induced inhibition of the ATP flow mediated by VDAC was revealed in isolated mitochondria
Generalized dynamical density functional theory for classical fluids and the significance of inertia and hydrodynamic interactions
We study the dynamics of a colloidal fluid including inertia and hydrodynamic
interactions, two effects which strongly influence the non-equilibrium
properties of the system. We derive a general dynamical density functional
theory (DDFT) which shows very good agreement with full Langevin dynamics. In
suitable limits, we recover existing DDFTs and a Navier-Stokes-like equation
with additional non-local terms.Comment: 5 pages, 4 figures, 4 supplementary movie files, I supplementary pd
Snap evaporation of droplets on smooth topographies
Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a “stick-slip” sequence—a combination of pinning and de-pinning events dominated by static friction or “pinning”, caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications
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