Miracle-dz/UniFAR-FTUs huggingface dataset:
Twin-width III: Max Independent Set and Coloring

We recently introduced the graph invariant twin-width, and showed that first-order model checking can be solved in time $f(d,k)n$ for $n$-vertex graphs given with a witness that the twin-width is at most $d$, called $d$-contraction sequence or $d$-sequence, and formulas of size $k$ [Bonnet et al., FOCS '20]. The inevitable price to pay for such a general result is that $f$ is a tower of exponentials of height roughly $k$. In this paper, we show that algorithms based on twin-width need not be impractical. We present $2^{O(k)}n$-time algorithms for $k$-Independent Set, $r$-Scattered Set, $k$-Clique, and $k$-Dominating Set when an $O(1)$-sequence is provided. We further show how to solve weighted $k$-Independent Set, Subgraph Isomorphism, and Induced Subgraph Isomorphism, in time $2^{O(k \log k)}n$. These algorithms are based on a dynamic programming scheme following the sequence of contractions forward. We then show a second algorithmic use of the contraction sequence, by starting at its end and rewinding it. As an example of this reverse scheme, we present a polynomial-time algorithm that properly colors the vertices of a graph with relatively few colors, establishing that bounded twin-width classes are $\chi$-bounded. This significantly extends the $\chi$-boundedness of bounded rank-width classes, and does so with a very concise proof. The third algorithmic use of twin-width builds on the second one. Playing the contraction sequence backward, we show that bounded twin-width graphs can be edge-partitioned into a linear number of bicliques, such that both sides of the bicliques are on consecutive vertices, in a fixed vertex ordering. Given that biclique edge-partition, we show how to solve the unweighted Single-Source Shortest Paths and hence All-Pairs Shortest Paths in sublinear time $O(n \log n)$ and time $O(n^2 \log n)$, respectively.
Performance Analysis of Noise Subspace-based Narrowband Direction-of-Arrival (DOA) Estimation Algorithms on CPU and GPU

High-performance computing of array signal processing problems is a critical task as real-time system performance is required for many applications. Noise subspace-based Direction-of-Arrival (DOA) estimation algorithms are popular in the literature since they provide higher angular resolution and higher robustness. In this study, we investigate various optimization strategies for high-performance DOA estimation on GPU and comparatively analyze alternative implementations (MATLAB, C/C++ and CUDA). Experiments show that up to 3.1x speedup can be achieved on GPU compared to the baseline multi-threaded CPU implementation. The source code is publicly available at the following link: this https URL
Responses of Benthic Invertebrate Communities to Shoreline Retrogressive Thaw Slumps in Arctic Upland Lakes

Abstract: Permafrost disturbance (shoreline retrogressive thaw slumping [SRTS]) causes solute-rich terrestrial inputs to Arctic tundra lakes. Eight upland tundra lakes (3 undisturbed [U], 5 disturbed [D]) in the Inuvik region of the Northwest Territories, Canada, were sampled to assess the effects of SRTS on benthic invertebrate community structure, abundance, and whether localized SRTS effects in D lakes could be discriminated by comparing samples taken adjacent to (Da) or further from (Do) the disturbance. Community composition and abundance differed between U and D lakes. Macroinvertebrates were more abundant in areas adjacent to SRTS (Da) than in areas away from SRTS (Do), but community composition did not differ between Da and Do areas. Abundance was >2× greater in D than in U lakes. Ostracoda abundance was 4× greater in D than U lakes and 2× higher in Da than Do areas. Nematoda abundance was ∼10× higher in D than U lakes, whereas Chironomidae abundance was lower in D than U lakes. Bivalvia and Oligochaeta had similar abundance in D and U lakes, and both groups were more abundant in Da than Do areas. Differences in abundance and community composition were related primarily to higher concentrations of Ca2+ in D than U sediments and to higher organic C and N in U than D sediments. Sediment organic C and Mg concentrations, macrophyte biomass, and dissolved organic C concentrations best explained differences in community composition among lake types and areas. Our study adds to our understanding of cascading changes in the foodweb structure and ecological states of freshwater ecosystems caused by climate change in the Arctic.
Determining mass-accretion and jet mass-loss rates in post-asymptotic giant branch binary systems

Aims. In this study we determine the morphology and mass-loss rate of jets emanating from the companion in post-asymptotic giant branch (post-AGB) binary stars with a circumbinary disc. In doing so we also determine the mass-accretion rates onto the companion, and investigate the source feeding the circum-companion accretion disc. Methods. We perform a spatio-kinematic modelling of the jet of two well-sampled post-AGB binaries, BD+46°442 and IRAS 19135+3937, by fitting the orbital phased time series of Hα spectra. Once the jet geometry, velocity, and scaled density structure are computed, we carry out radiative transfer modelling of the jet for the first four Balmer lines to determine the jet densities, thus allowing us to compute the jet mass-loss rates and mass-accretion rates. We distinguish the origin of the accretion by comparing the computed mass-accretion rates with theoretically estimated mass-loss rates, both from the post-AGB star and from the circumbinary disc. Results. The spatio-kinematic model of the jet reproduces the observed absorption feature in the Hα lines. The jets have an inner region with extremely low density in both objects. The jet model for BD+46°442 is tilted by 15° with respect to the orbital axis of the binary system. IRAS 19135+3937 has a smaller tilt of 6°. Using our radiative transfer model, we find the full 3D density structure of both jets. By combining these results, we can compute the mass-loss rates of the jets, which are of the order of 10−7 − 10−5 M⊙ yr−1. From this we estimate mass-accretion rates onto the companion of 10−6 − 10−4 M⊙ yr−1. Conclusions. Based on the mass-accretion rates found for these two objects, we conclude that the circumbinary disc is most likely the source feeding the circum-companion accretion disc. This is in agreement with the observed depletion patterns in post-AGB binaries, which is caused by re-accretion of gas from the circumbinary disc that is under-abundant in refractory elements. The high accretion rates from the circumbinary disc imply that the lifetime of the disc will be short. Mass transfer from the post-AGB star cannot be excluded in these systems, but it is unlikely to provide a sufficient mass-transfer rate to sustain the observed jet mass-loss rates.
Optimal Probabilistic Motion Planning with Partially Infeasible LTL Constraints

This paper studies optimal probabilistic motion planning of a mobile agent in an uncertain environment where pre-specified tasks might not be fully realized. The agent's motion is modeled by a probabilistic labeled Markov decision process (MDP). A relaxed product MDP is developed, which allows the agent to revise its motion plan to not strictly follow the desired LTL constraints whenever the task is found to be infeasible. To evaluate the revised motion plan, a utility function composed of violation and implementation cost is developed, where the violation cost function is designed to quantify the differences between the revised and the desired motion plan, and the implementation cost are designed to bias the selection towards cost-efficient plans. Based on the developed utility function, a multi-objective optimization problem is formulated to jointly consider the implementation cost, the violation cost, and the satisfaction probability of tasks. Cost optimization in both prefix and suffix of the agent trajectory is then solved via coupled linear programs. Simulation results are provided to demonstrate its effectiveness.
Nonequilibrium theory of enzyme chemotaxis and enhanced diffusion

Enhanced diffusion and anti-chemotaxis of enzymes have been reported in several experiments in the last decade, opening up entirely new avenues of research in the bio-nanosciences both at the applied and fundamental level. Here, we introduce a novel theoretical framework, rooted in non-equilibrium effects characteristic of catalytic cycles, that explains all observations made so far in this field. In addition, our theory predicts entirely novel effects, such as dissipation-induced switch between anti-chemotactic and chemotactic behavior.
Quantifying Modal Thermal Conductivity in Amorphous Silicon

While there are several methods, e.g., anharmonic lattice dynamics and normal mode decomposition, to compute the modal lattice vibrational information in perfect crystals, the modal information of vibrations, e.g., vibrational relaxation time, group velocity and mean free path, in amorphous solids are still challenge to be captured. By systematically analyzing the normal mode decomposition and structure factor methods, we conclude that the vibrational dispersion can be calculated by applying effective wave vectors in the structure factor method, while the vibrational relaxation time calculated by the normal mode decomposition method is questionable since the group velocity cannot be defined on the Gamma point. We also show that the anharmonicity caused by the system temperature has little effect on the relaxation times of the propagating modes in amorphous materials, and therefore, the corresponding modal and total thermal conductivity is temperature independent when all the vibrations are assumed to be excited. The non-propagating modes, i.e., diffusons, conduct heat via thermal coupling between different vibrational modes, and can be calculated by harmonic lattice dynamics using Allen-Feldman theory. As a result, the thermal conductivity contributed from diffusons is also temperature independent when all the vibrational modes are activated which is the situation in molecular dynamics simulations. The total thermal conductivity concerning both propagons (50%) and diffusons (50%) agree quite well with the results computed using Green-Kubo equilibrium molecular dynamics. By correcting the excitation state of the vibrations in amorphous solids, the thermal conductivity calculated by the structure factor method and Allen-Feldman theory can fully capture the experimentally measured temperature-dependent thermal conductivity.
Analysis and validation of the digital chain relating to architectural design process Achievement of a folded structure composed of wood panels

The research presented in this paper revolves around the experimental development of the morpho-structural potential of folded architectural structures made of wood. The aims are to develop an innovative system for timber used in sustainable construction and to increase the inventory of wood architectural tectonics. First, this article provides a characterization of the digital chain associated to the development of non-standard folded structures consisting of wood panels. The purpose is to study the architectural design process from parametric modeling (through CNC machining) and assembly operations to production by way of a full-scale experimental pavilion. Secondly, a number of analytical experiments have been performed towards the completion of the pavilion, in order to validate the design process.
CovMUNET: A Multiple Loss Approach towards Detection of COVID-19 from Chest X-ray

The recent outbreak of COVID-19 has halted the whole world, bringing a devastating effect on public health, global economy, and educational systems. As the vaccine of the virus is still not available, the most effective way to combat the virus is testing and social distancing. Among all other detection techniques, the Chest X-ray (CXR) based method can be a good solution for its simplicity, rapidity, cost, efficiency, and accessibility. In this paper, we propose CovMUNET, which is a multiple loss deep neural network approach to detect COVID-19 cases from CXR images. Extensive experiments are performed to ensure the robustness of the proposed algorithm and the performance is evaluated in terms of precision, recall, accuracy, and F1-score. The proposed method outperforms the state-of-the-art approaches with an accuracy of 96.97% for 3-class classification (COVID-19 vs normal vs pneumonia) and 99.41% for 2-class classification (COVID vs non-COVID). The proposed neural architecture also successfully detects the abnormality in CXR images.
Non-linear interferometry with infrared metasurfaces

Abstract The optical elements comprised of sub-diffractive light scatterers, or metasurfaces, hold a promise to reduce the footprint and unfold new functionalities of optical devices. A particular interest is focused on metasurfaces for manipulation of phase and amplitude of light beams. Characterisation of metasurfaces can be performed using interferometry, which, however, may be cumbersome, specifically in the infrared (IR) range. Here, we realise a new method for characterising metasurfaces operating in the telecom IR range using accessible components for visible light. Correlated IR and visible photons are launched into a non-linear interferometer so that the phase profile, imposed by the metasurface on the IR photons, modifies the interference at the visible photon wavelength. Furthermore, we show that this concept can be used for broadband manipulation of the intensity profile of a visible beam using a single IR metasurface. Our method unfolds the potential of quantum interferometry for the characterization of advanced optical elements.
A new GPU library for fast simulation of large-scale networks of spiking neurons

Over the past decade there has been a growing interest in the development of parallel hardware systems for simulating large-scale networks of spiking neurons. Compared to other highly-parallel systems, GPU-accelerated solutions have the advantage of a relatively low cost and a great versatility, thanks also to the possibility of using the CUDA-C/C++ programming languages. NeuronGPU is a GPU library for large-scale simulations of spiking neural network models, written in the C++ and CUDA-C++ programming languages, based on a novel spike-delivery algorithm. This library includes simple LIF (leaky-integrate-and-fire) neuron models as well as several multisynapse AdEx (adaptive-exponential-integrate-and-fire) neuron models with current or conductance based synapses, user definable models and different devices. The numerical solution of the differential equations of the dynamics of the AdEx models is performed through a parallel implementation, written in CUDA-C++, of the fifth-order Runge-Kutta method with adaptive step-size control. In this work we evaluate the performance of this library on the simulation of a well-known cortical microcircuit model, based on LIF neurons and current-based synapses, and on a balanced networks of excitatory and inhibitory neurons, using AdEx neurons and conductance-based synapses. On these models, we will show that the proposed library achieves state-of-the-art performance in terms of simulation time per second of biological activity. In particular, using a single NVIDIA GeForce RTX 2080 Ti GPU board, the full-scale cortical-microcircuit model, which includes about 77,000 neurons and $3 \cdot 10^8$ connections, can be simulated at a speed very close to real time, while the simulation time of a balanced network of 1,000,000 AdEx neurons with 1,000 connections per neuron was about 70 s per second of biological activity.
Is NGC 300 a pure exponential disk galaxy?

NGC 300 is a low-mass disk galaxy in the Sculptor group. In the literature, it has been identified as a pure exponential disk galaxy, as its luminosity profile can be well fit with a single exponential law over many disk scale lengths (Type I). We investigate the stellar luminosity distribution of NGC 300 using Hubble Space Telescope archive data, reaching farther and deeper than any other previous studies. Color-magnitude diagrams show a significant population of old red giant branch (RGB) stars in all fields out to R ∼ 19 kpc (32′), as well as younger populations in the inner regions. We construct the density profiles of the young, intermediate-aged, and old stellar populations, and find two clear breaks in the density profiles of the old RGB and intermediate-aged stars: one down bending (Type II) at R ∼ 5.9 kpc, and another up bending (Type III) at R ∼ 8.3 kpc. Moreover, the old RGB stars exhibit a negative radial color gradient with an upward bend at R ∼ 8 kpc, beyond which the stellar populations are uniformly old (>7 Gyr) and metal poor ([Fe/H] = −1.6−0.4+0.2 dex). The outer stellar component at R ⪆ 8 kpc is therefore well separated from the inner disk in terms of stellar density and stellar population. While our results cast doubt on the currently established wisdom that NGC 300 is a pure exponential disk galaxy, a more detailed survey should be carried out to identify the outskirts as either a disk or a stellar halo.
Groups of Worldview Transformations Implied by Isotropy of Space

Given any Euclidean ordered field, Q, and any 'reasonable' group, G, of (1+3)-dimensional spacetime symmetries, we show how to construct a model MG of kinematics for which the set W of worldview transformations between inertial observers satisfies W=G. This holds in particular for all relevant subgroups of Gal, cPoi, and cEucl (the groups of Galilean, Poincare and Euclidean transformations, respectively, where c∈Q is a model-specific parameter orresponding to the speed of light in the case of Poincare transformations). In doing so, by an elementary geometrical proof, we demonstrate our main contribution: spatial isotropy is enough to entail that the set W of worldview transformations satisfies either W⊆Gal, W⊆cPoi, or W⊆cEucl for some c>0. So assuming spatial isotropy is enough to prove that there are only 3 possible cases: either the world is classical (the worldview transformations between inertial observers are Galilean transformations); the world is relativistic (the worldview transformations are Poincare transformations); or the world is Euclidean (which gives a nonstandard kinematical interpretation to Euclidean geometry). This result considerably extends previous results in this field, which assume a priori the (strictly stronger) special principle of relativity, while also restricting the choice of Q to the field of reals. As part of this work, we also prove the rather surprising result that, for any G containing translations and rotations fixing the time-axis t, the requirement that G be a subgroup of one of the groups Gal, cPoi or cEucl is logically equivalent to the somewhat simpler requirement that, for all g∈G: g[t] is a line, and if g[t]=t then g is a trivial transformation (i.e. g is a linear transformation that preserves Euclidean length and fixes the time-axis setwise).
Fertilizer options for sustainable maize (Zea mays L.) production in the Trans Nzoia district of Kenya.

With increasing human population against declining staple food crop yield trend, food insecurity is inevitable. Soil fertility problem has been identified as a major factor hindering maize productivity in Trans Nzoia district. Majority of these soils are acidic, deficient in nitrogen, phosphorus and at times other nutrient elements. A factorial experiment was laid out in randomised complete block design, with fertilizer option being main plot and variety as sub plot to explore better fertilizer treatments for maize production in Trans Nzoia. The treatments included three maize varieties and five fertilizer options. The maize varieties used were H.614D, H.6213, H.9401, while the fertilizer options included control (no fertilizer), farmyard manure (FYM) (one handful per hole), single super phosphate-SSP (188 kg/ha), diammonium phosphate-DAP (188 kg/ha) and DAP 125 kg/ha). There were significant yield differences among fertilizer treatments and among the varieties. DAP at 188 kg/ha and H.6213 gave the best mean yields of 10.19 and 9.62 kg a plot, respectively. SSP at 188 kg/ha and H 614 D treatments resulted in dismal crop yield performance of 8.03 and 8.46 kg a plot, respectively. Up to 23% yield can be lost in the field as rots especially with maize varieties exhibiting open cob tips.
Degradation of chlorinated benzoic acid mixtures by plant–bacteria associations

Phytoremediation technologies must tolerate and degrade mixtures of contaminants, as most contaminated sites contain mixtures of compounds. This study assessed the ability of plant–bacteria associations to degrade mixtures of mono‐ and dichlorinated benzoic acids. Sixteen forage grasses and combinations of these grasses with several bacterial inoculants were screened for growth in soil contaminated with various concentrations of mono‐ or dichlorinated benzoic acids. Dahurian wild rye (Elymus dauricus) inoculated with a combination of Pseudomonas aeruginosa strain R75 and Pseudomonas savastanoi strain CB35 reduced 3‐chlorobenzoic acid (3CBA) levels in soil by 74% (i.e., 583 to 149 mg/kg). Meadow brome (Bromus biebersteinii) inoculated with Alcaligenes sp. strain BR60 reduced 2,3‐dichlorobenzoic acid (23diCBA) levels in soil by 56% (i.e., 125 to 55 mg/kg). Altai wild rye (Elymus angitus) inoculated with strains R75 and CB35 reduced 2,5‐dichlorobenzoic acid (25diCBA) levels in soil by 46% (i.e., 211 to 113 mg/kg). Two plant–bacteria associations and uninoculated Dahurian wild rye also degraded mixtures of 3CBA, 23diCBA, or 25diCBA. When 25diCBA was mixed with 23diCBA, uninoculated Dahurian wild rye reduced levels of 25diCBA in soil by 31% and reduced the levels of both 25diCBA and 3CBA by up to 64% when these two contaminants were present in a mixture. Similarly, meadow brome inoculated with BR60 reduced 23diCBA and 3CBA levels by up to 50%. Levels of all three chlorinated benzoic acids were reduced by 53 to 63% by Altai wild rye inoculated with strains R75 and CB35. Our results indicate that plant–bacteria associations can tolerate and degrade mixtures of contaminants in soil but that predictions about phytoremediation of mixed contaminants may not be straightforward.
Visible Shapes of Black Holes M87* and SgrA*

We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background behind the black hole at the distance exceeding the so-called photon spheres. The notably smaller dark shadow (dark silhouette) of the black hole event horizon is visible if the black hole is highlighted by the inner parts of the luminous accreting matter inside the photon spheres. The first image of the supermassive black hole M87*, obtained by the Event Horizon Telescope collaboration, shows the lensed dark image of the southern hemisphere of the black hole event horizon globe, highlighted by accreting matter, while the classical black hole shadow is invisible at all. A size of the dark spot on the Event Horizon Telescope (EHT) image agrees with a corresponding size of the dark event horizon silhouette in a thin accretion disk model in the case of either the high or moderate value of the black hole spin, a≳0.75.