SeDAR: Reading Floorplans Like a Human—Using Deep Learning to Enable Human-Inspired Localisation

This is the final version. Available from Springer Verlag via the DOI in this record. The use of human-level semantic information to aid robotic tasks has recently become an important area for both Computer Vision and Robotics. This has been enabled by advances in Deep Learning that allow consistent and robust semantic understanding. Leveraging this semantic vision of the world has allowed human-level understanding to naturally emerge from many different approaches. Particularly, the use of semantic information to aid in localisation and reconstruction has been at the forefront of both fields. Like robots, humans also require the ability to localise within a structure. To aid this, humans have designed high-level semantic maps of our structures called floorplans. We are extremely good at localising in them, even with limited access to the depth information used by robots. This is because we focus on the distribution of semantic elements, rather than geometric ones. Evidence of this is that humans are normally able to localise in a floorplan that has not been scaled properly. In order to grant this ability to robots, it is necessary to use localisation approaches that leverage the same semantic information humans use. In this paper, we present a novel method for semantically enabled global localisation. Our approach relies on the semantic labels present in the floorplan. Deep Learning is leveraged to extract semantic labels from RGB images, which are compared to the floorplan for localisation. While our approach is able to use range measurements if available, we demonstrate that they are unnecessary as we can achieve results comparable to state-of-the-art without them.EPSRCInnovate UKNVIDIA Corporatio

Taking the Scenic Route to 3D: Optimising Reconstruction from Moving Cameras

This is the author accepted manuscript The final version is available from IEEE via the DOI in this record.Reconstruction of 3D environments is a problem that has been widely addressed in the literature. While many approaches exist to perform reconstruction, few of them take an active role in deciding where the next observations should come from. Furthermore, the problem of travelling from the camera’s current position to the next, known as pathplanning, usually focuses on minimising path length. This approach is ill-suited for reconstruction applications, where learning about the environment is more valuable than speed of traversal. We present a novel Scenic Route Planner that selects paths which maximise information gain, both in terms of total map coverage and reconstruction accuracy. We also introduce a new type of collaborative behaviour into the planning stage called opportunistic collaboration, which allows sensors to switch between acting as independent Structure from Motion (SfM) agents or as a variable baseline stereo pair. We show that Scenic Planning enables similar performance to state-of-the-art batch approaches using less than 0.00027% of the possible stereo pairs (3% of the views). Comparison against length-based pathplanning approaches show that our approach produces more complete and more accurate maps with fewer frames. Finally, we demonstrate the Scenic Pathplanner’s ability to generalise to live scenarios by mounting cameras on autonomous ground-based sensor platforms and exploring an environment.This work was funded by the SNSF Project SMILE grant CR-SII2_160811

Exposure to fine aerosols in sleeping environments of Lisbon dwellings

Trabalho apresentado em European Aerosol Conference 2023 (EAC2023), September 3−8, 2023, Malaga, SpainN/

Correlated Timing and Spectral Variations of the Soft X-ray Transient Aquila X-1: Evidence for an Atoll classification

Based on Rossi X-ray Timing Explorer data, we discuss the classification of the soft X-ray transient Aquila X-1 in the Z/atoll scheme, and the relation of its kilohertz quasi-periodic oscillations (kHz QPO) properties to the X-ray colors. The color-color diagram shows one elongated ("banana") structure and several "islands" of data points. The power spectra of the island are best represented by a broken power-law, whereas those of the banana by a power-law below ~ 1 Hz plus an exponentially cut-off component at intermediate frequencies (30-60 Hz). The parameters of these two components change in correlation with the position of the source in the color-color diagram. Based on the pattern that the source shows in the color-color diagram and its aperiodic variability we conclude that Aquila X-1 is an atoll source. We have also investigated the possible correlation between the frequency of the kHz QPO and the position of the source in the color-color diagram. The complexity seen in the frequency versus count rate diagram is reduced to a single track when the frequency is plotted against hard or soft color.Comment: 9 pages, 5 figures. Accepted for publication in Ap

kHz Quasi Periodic Oscillations in Low Mass X-ray Binaries as Probes of General Relativity in the Strong Field Regime

We consider the interpretation of a pair of kHz Quasi Periodic Oscillations (QPOs) in the Fourier spectra of two Low Mass X-Ray Binaries, Sco X-1 and 4U1608-52, hosting an old accreting neutron star. The observed frequency difference of these QPOs decreaseas as their frequency increases, contrary to simple beat frequency models, which predict a constant frequency difference. We show that the behaviour of these QPOs is instead well matched in terms of the fundamental frequencies (in the radial and azimuthal directions) for test particle motion in the gravitational field of the neutron star, for reasonable star masses, and nearly independent of the star spin. The radial frequency must be much smaller than the azimuthal one, testifying that kHz QPOs are produced close to the innermost stable orbit. These results are not reproduced through the post--Newtonian (PN) approximation of General Relativity (GR). kHz QPOs from X-ray binaries likely provide an accurate laboratory for strong field GR.Comment: to appear in Physical Review Letters, PRL Latex plus 2 figures in standard PostScript forma

IFN-γ-producing CD4+ T cells promote experimental cerebral malaria by modulating CD8+ T cell accumulation within the brain.

It is well established that IFN-γ is required for the development of experimental cerebral malaria (ECM) during Plasmodium berghei ANKA infection of C57BL/6 mice. However, the temporal and tissue-specific cellular sources of IFN-γ during P. berghei ANKA infection have not been investigated, and it is not known whether IFN-γ production by a single cell type in isolation can induce cerebral pathology. In this study, using IFN-γ reporter mice, we show that NK cells dominate the IFN-γ response during the early stages of infection in the brain, but not in the spleen, before being replaced by CD4(+) and CD8(+) T cells. Importantly, we demonstrate that IFN-γ-producing CD4(+) T cells, but not innate or CD8(+) T cells, can promote the development of ECM in normally resistant IFN-γ(-/-) mice infected with P. berghei ANKA. Adoptively transferred wild-type CD4(+) T cells accumulate within the spleen, lung, and brain of IFN-γ(-/-) mice and induce ECM through active IFN-γ secretion, which increases the accumulation of endogenous IFN-γ(-/-) CD8(+) T cells within the brain. Depletion of endogenous IFN-γ(-/-) CD8(+) T cells abrogates the ability of wild-type CD4(+) T cells to promote ECM. Finally, we show that IFN-γ production, specifically by CD4(+) T cells, is sufficient to induce expression of CXCL9 and CXCL10 within the brain, providing a mechanistic basis for the enhanced CD8(+) T cell accumulation. To our knowledge, these observations demonstrate, for the first time, the importance of and pathways by which IFN-γ-producing CD4(+) T cells promote the development of ECM during P. berghei ANKA infection

Fire debris analysis by Raman spectroscopy and chemometrics

A paper reporting the use of Raman Spectroscopy in fire debris analysis is presented. Five polymer based samples, namely carpet (polypropylene), nylon stockings (nylon), foam packaging (polystyrene), CD cases (polystyrene) and DVD cases (polypropylene) were burnt with each one of the following ignitable liquids: petrol, diesel, kerosene and ethanol. Raman shifts were obtained and, in some cases, peaks were identified to correspond to pyrolysis products in the form of alkanes, aromatic or polyaromatic compounds. All pyrolysis peaks were used to produce a Principal Component Analysis (PCA) of the burned samples with the different ignitable liquids. The change in the Raman spectra made it possible to identify some of the pyrolysis products produced in the combustion and also to identify the different plastic materials in fire debris, even when different fuels have been used and the chemical and structural identity of the plastic has been altered in the fire

Intracluster stars in the Virgo cluster core

We have investigated the properties of the diffuse light in the Virgo cluster core region, based on the detection of intracluster planetary nebulae (PNe) in four fields. We eliminate the bias from misclassified faint continuum objects, using improved Monte Carlo simulations, and the contaminations by high redshift Ly$\alpha$ galaxies, using the Ly$\alpha$ luminosity function in blank fields. Recent spectroscopic observations confirm that our photometric PN samples are well-understood. We find that the diffuse stellar population in the Virgo core region is inhomogeneous on scales of 30'-90': there exist significant field-to-field variations in the number density of PNe and the inferred amount of intracluster light, with some empty fields, some fields dominated by extended Virgo galaxy halos, and some fields dominated by the true intracluster component. There is no clear trend with distance from M87. The mean surface luminosity density, its rms variation, and the mean surface brightness of diffuse light in our 4 fields are $\Sigma_B = 2.7 x 10^{6}$ L$_{B\odot}$ arcmin$^{-2}$, ${rms} = 2.1 \times 10^{6}$ L$_{B\odot}$ arcmin$^{-2}$, and $\bar{\mu}_{B}=29.0$ mag arcsec$^{-2}$ respectively. Our results indicate that the Virgo cluster is a dynamically young environment, and that the intracluster component is associated at least partially with local physical processes like galaxy interactions or harassment. We also argue, based on kinematic evidence, that the so-called 'over-luminous' PNe in the halo of M84 are dynamically associated with this galaxy, and must thus be brighter than and part of a different stellar population from the normal PN population in elliptical galaxies.Comment: 31 pages, 6 figure. In press on the Astronomical Journa

Resonant Tunneling through Linear Arrays of Quantum Dots

We theoretically investigate resonant tunneling through a linear array of quantum dots with subsequent tunnel coupling. We consider two limiting cases: (i) strong Coulomb blockade, where only one extra electron can be present in the array (ii) limit of almost non-interacting electrons. We develop a density matrix description that incorporates the coupling of the dots to reservoirs. We analyze in detail the dependence of the stationary current on the electron energies, tunnel matrix elements and rates, and on the number of dots. We describe interaction and localization effects on the resonant current. We analyze the applicability of the approximation of independent conduction channels. We find that this approximation is not valid when at least one of the tunnel rates to the leads is comparable to the energy splitting of the states in the array. In this case the interference of conduction processes through different channels suppresses the current.Comment: 12 pages, 5 figure