Characterisation of cyclic variability in an optically accessible IC Engine by means of phase-independent POD

Investigation of cyclic variability in engine operation has recently received new impulse with the widespread application of advanced numerical and experimental techniques. The present work attempts to shed some light on the existence and nature of correlations between coherent structures dynamics and cyclic variability in IC engines by means of phase-independent Proper Orthogonal Decomposition applied to highly-resolved PIV measurements obtained in an optically accessible, motored engine. Analysis of the conditional means and variances of the reconstruction coefficients reveal interesting patterns in the break-up of coherent structures which are also confirmed by experimental observation and leave room for speculation on the true nature of the flow field at different crank angles. A first attempt has also been carried out to reconstruct missing information from available measurements, with encouraging results: the development of such interpolation/reconstruction technique could obviously have a great impact on the reduction of the cost normally involved in experimental and computational campaigns

Polarimetric Thermal to Visible Face Verification via Self-Attention Guided Synthesis

Polarimetric thermal to visible face verification entails matching two images that contain significant domain differences. Several recent approaches have attempted to synthesize visible faces from thermal images for cross-modal matching. In this paper, we take a different approach in which rather than focusing only on synthesizing visible faces from thermal faces, we also propose to synthesize thermal faces from visible faces. Our intuition is based on the fact that thermal images also contain some discriminative information about the person for verification. Deep features from a pre-trained Convolutional Neural Network (CNN) are extracted from the original as well as the synthesized images. These features are then fused to generate a template which is then used for verification. The proposed synthesis network is based on the self-attention generative adversarial network (SAGAN) which essentially allows efficient attention-guided image synthesis. Extensive experiments on the ARL polarimetric thermal face dataset demonstrate that the proposed method achieves state-of-the-art performance.Comment: This work is accepted at the 12th IAPR International Conference On Biometrics (ICB 2019

Laser induced modulation of the Landau level structure in single-layer graphene

We present perturbative analytical results of the Landau level quasienergy spectrum, autocorrelation function and out of plane pseudospin polarization for a single graphene sheet subject to intense circularly polarized terahertz radiation. For the quasienergy spectrum, we find a striking non trivial level-dependent dynamically induced gap structure. This photoinduced modulation of the energy band structure gives rise to shifts of the revival times in the autocorrelation function and it also leads to modulation of the oscillations in the dynamical evolution of the out of plane pseudospin polarization, which measures the angular momentum transfer between light and graphene electrons. For a coherent state, chosen as an initial pseudospin configuration, the dynamics induces additional quantum revivals of the wave function that manifest as shifts of the maxima and minima of the autocorrelation function, with additional partial revivals and beating patterns. These additional maxima and beating patterns stem from the effective dynamical coupling of the static eigenstates. We discuss the possible experimental detection schemes of our theoretical results and their relevance in new practical implementation of radiation fields in graphene physics.Comment: 12 pages, 5 figures. Accepted version for publication in Physical Review

X-Ray Grating Observations of Recurrent Nova T Pyxidis During The 2011 Outburst

The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and XMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011 April 14 outburst. The X-ray spectra show prominent emission lines of C, N, and O, with broadening corresponding to a full width at half maximum of ~2000-3000 km/s, and line ratios consistent with high-density plasma in collisional ionization equilibrium. On day 210 we also measured soft X-ray continuum emission that appears to be consistent with a white dwarf (WD) atmosphere at a temperature ~420,000 K, partially obscured by anisotropic, optically thick ejecta. The X-ray continuum emission is modulated with the photometric and spectroscopic period observed in quiescence. The continuum at day 235 indicated a WD atmosphere at a consistent effective temperature of 25 days earlier, but with a lower flux. The effective temperature indicates a mass of ~1 solar mass. The conclusion of partial WD obscuration is supported by the complex geometry of non-spherically-symmetric ejecta confirmed in recent optical spectra obtained with the Southern African Large Telescope (SALT) in November and December of 2012. These spectra exhibited prominent [O III] nebular lines with velocity structures typical of bipolar ejecta.Comment: Accepted to ApJ 2013 October 23, 14 pages, 9 figures, 3 table

Focus ion beam/scanning electron microscopy characterization of osteoclastic resorption of calcium phosphate substrates

This article presents the application of dual focused ion beam/scanning electron microscopy (FIB-SEM) imaging for preclinical testing of calcium phosphates with osteoclast precursor cells and how this high-resolution imaging technique is able to reveal microstructural changes at a level of detail previously not possible. Calcium phosphate substrates, having similar compositions but different microstructures, were produced using low- and high-temperature processes (biomimetic calcium-deficient hydroxyapatite [CDHA] and stoichiometric sintered hydroxyapatite, respectively). Human osteoclast precursor cells were cultured for 21 days before evaluating their resorptive potential on varying microstructural features. Alternative to classical morphological evaluation of osteoclasts (OC), FIB-SEM was used to observe the subjacent microstructure by transversally sectioning cells and observing both the cells and the substrates. Resorption pits, indicating OC activity, were visible on the smoother surface of high-temperature sintered hydroxyapatite. FIB-SEM analysis revealed signs of acidic degradation on the grain surface under the cells, as well as intergranular dissolution. No resorption pits were evident on the surface of the rough CDHA substrates. However, whereas no degradation was detected by FIB sections in the material underlying some of the cells, early stages of OC-mediated acidic degradation were observed under cells with more spread morphology. Collectively, these results highlight the potential of FIB to evaluate the resorptive activity of OC, even in rough, irregular, or coarse surfaces where degradation pits are otherwise difficult to visualize.Peer ReviewedPostprint (author's final draft

Coexisting patterns of population oscillations: the degenerate Neimark Sacker bifurcation as a generic mechanism

We investigate a population dynamics model that exhibits a Neimark Sacker bifurcation with a period that is naturally close to 4. Beyond the bifurcation, the period becomes soon locked at 4 due to a strong resonance, and a second attractor of period 2 emerges, which coexists with the first attractor over a considerable parameter range. A linear stability analysis and a numerical investigation of the second attractor reveal that the bifurcations producing the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure

Oxysterol-Binding Protein-1 (OSBP1) Modulates Processing and Trafficking of the Amyloid Precursor Protein

BACKGROUND Evidence from biochemical, epidemiological and genetic findings indicates that cholesterol levels are linked to amyloid-β (Aβ) production and Alzheimer's disease (AD). Oxysterols, which are cholesterol-derived ligands of the liver X receptors (LXRs) and oxysterol binding proteins, strongly regulate the processing of amyloid precursor protein (APP). Although LXRs have been studied extensively, little is known about the biology of oxysterol binding proteins. Oxysterol-binding protein 1 (OSBP1) is a member of a family of sterol-binding proteins with roles in lipid metabolism, regulation of secretory vesicle generation and signal transduction, and it is thought that these proteins may act as sterol sensors to control a variety of sterol-dependent cellular processes. RESULTS We investigated whether OSBP1 was involved in regulating APP processing and found that overexpression of OSBP1 downregulated the amyloidogenic processing of APP, while OSBP1 knockdown had the opposite effect. In addition, we found that OSBP1 altered the trafficking of APP-Notch2 dimers by causing their accumulation in the Golgi, an effect that could be reversed by treating cells with OSBP1 ligand, 25-hydroxycholesterol. CONCLUSION These results suggest that OSBP1 could play a role in linking cholesterol metabolism with intracellular APP trafficking and Aβ production, and more importantly indicate that OSBP1 could provide an alternative target for Aβ-directed therapeutic.National Institute on Aging (AG/NS17485

Rural Household Access to Assets and Agrarian Institutions: A Cross Country Comparison

Agriculture is at the core of the livelihoods of a large share of rural households throughout the developing world. Agricultural growth is a major engine for overall economic growth and possibly the single most important pathway out of poverty in the rural space. This paper characterizes household access to assets and agrarian institutions of households engaged in agricultural activities in a sample of developing countries. The evidence presented in the paper draws from 15 nationally representative household surveys from four regions of the developing world. We find that the access of rural households to a range of agricultural-specific assets (including land and livestock) and institutions is in general low, though highly heterogeneous across countries, and by categories of households within countries. A large share of rural agricultural households do not use or have access to basic productive inputs, agricultural support services or output markets, and in general it is the landless and the smallest landowners who suffer significantly more from this lack of access. We relate this to the households' ability to engage successfully in commercial farming and find consistent supporting evidence for the hypothesis that this lack of access is significantly constraining their potential to engage successfully in agriculture.rural non farm, assets, agrarian institutions, household surveys, Consumer/Household Economics, O13, O57, Q12,