FPGA-based multi-sensor relative navigation in space: Preliminary analysis in the framework of the I3DS H2020 project

The Horizon 2020 Integrated 3D Sensors (I3DS) project brings together the following entities throughout Europe: THALES ALENIA SPACE - France / Italy / UK / Spain, SINTEF (Norway), TERMA (Denmark), COSINE (Netherlands), PIAP Space (Poland), HERTZ Systems (Poland), and Cranfield University (UK). I3DS is co-funded under the Horizon 2020 EU research and development program and is part of the Strategic Research Cluster on Space Robotics Technologies. The ambition of I3DS is to produce a standardised modular Inspector Sensor Suite (INSES) for autonomous orbital and planetary applications for future space missions. Orbital applications encompass activities such as on-orbit servicing and repair, space rendezvous and docking, collision avoidance and active debris removal (ADR). Simultaneous localisation and surface mapping (SLAM) for planetary exploration and general navigation in an unknown environment for scientific purposes can be considered in planetary applications. These envisaged space applications can be tackled by exploiting the flexibility, high performance and long product life of FPGAs. Conventional FPGAs are subject to Single Event Upsets (SEU) due to space radiation, causing their failure. Therefore, space-graded FPGAs, such as those developed by Xilinx, are targeted within the I3DS project. Currently, the main use of the FPGA within the development of this robust end-to-end multi-sensor suite is for navigation and data preprocessing. The aim of this paper is to assess the capabilities of FPGAs to carry out complex operations, such as running navigation algorithms for space applications. The motivation for the development of the on-board software architecture is as follows: raw data, acquired from the various sensors – including, among others, a High Resolution camera, a stereo camera and a LiDAR – is pre-processed to ensure the provision of robust and optimised inputs to 3D navigation algorithms. Noise reduction and conversion into suitable formats for the successful application of navigation algorithms are therefore the main aims of the data pre-processing. Some techniques adopted in this phase include outlier rejection and data dimensionality reduction for large point clouds, e.g. from LiDAR, and geometric and radiometric correction of the images from the cameras. The pre-processed data will then feed state-of-the-art relative navigation algorithms. Some of the proposed navigation algorithms include Generalised Iterative Closest Point (GICP) for dense 3D point clouds, relative positioning with fiducial markers, and visual odometry. The system environment for the preliminary operation is a test-bench setup formed by a standard desktop computer and a non-space-graded FGA (Xilinx UltraZed-EG FPGA). The choice of FPGA was based on the similarity of this board to other spacegraded ones also provided by Xilinx. Experimental tests on the algorithms are being performed in the framework of the validation campaign for the I3DS project. Preliminary results indicate that the data pre-processing can be efficiently carried out on the FPGA board

Self-pulsing dynamics of ultrasound in a magnetoacoustic resonator

A theoretical model of parametric magnetostrictive generator of ultrasound is considered, taking into account magnetic and magnetoacoustic nonlinearities. The stability and temporal dynamics of the system is analized with standard techniques revealing that, for a given set of parameters, the model presents a homoclinic or saddle--loop bifurcation, which predicts that the ultrasound is emitted in the form of pulses or spikes with arbitrarily low frequency.Comment: 5 pages, 5 figure

Prospects for probing the gluon density in protons using heavy quarkonium hadroproduction

We examine carefully bottomonia hadroproduction in proton colliders, especially focusing on the LHC, as a way of probing the gluon density in protons. To this end we develop some previous work, getting quantitative predictions and concluding that our proposal can be useful to perform consistency checks of the parameterization sets of different parton distribution functions.Comment: LaTeX, 14 pages, 6 EPS figure

Phosphorylation of MAP Kinases crucially controls the response to environmental stress in Dunaliella viridis

The green unicellular microalga Dunaliella viridis has the ability to cope with a wide variety of environmental stressful conditions, such as thermal and osmotic shocks, high PAR, UV radiation and nitrogen deficiency. The lack of a rigid cell wall makes D. viridis an excellent model organism to study stress signaling in eukaryotic unicellular organisms. Mitogen-activated protein kinases (MAPKs) are highly conserved serine/threonine kinases that convert extracellular stimuli into a wide range of responses at both cellular and nuclear levels. In eukaryotic cells, MAPKs are involved in both cell proliferation and differentiation (ERK pathway) and stress responses (JNK and p38 pathways), through protein kinase cascades. Significantly lesser phosphorylation levels of ERK-like protein were observed in D. viridis cultures acclimated to high salinity (3-4 M NaCl). In contrast, JNK-like and p38-like proteins phosphorylation levels increased in stressed cells. Likewise, the efficacy of specific commercial inhibitors of the phosphorylation of ERK (PD98059), JNK (SP600125) and p38 (SB203580) revealed the importance of JNK-like proteins in the maintenance of cell viability, the highlighted participation of p38-like proteins and the non-direct implication of the ERK-like proteins in the acclimatization process. In summary, specific blockade of JNK- and p38-like cascades in stressed cells led to rapid cell death. The behavior of MAPK-like proteins in algae is not known in depth, so the analysis of their mechanism of action, as well as their function in this model microalga, will allow to estimate the fate of unicellular eukaryotic organisms in aquatic ecosystems subjected to environmental stress derived from the conditions prevailing within a framework of global climate change.Peer reviewe

Sharp acoustic vortex focusing by Fresnel-spiral zone plates

[EN] We report the optimal focusing of acoustic vortex beams by using flat lenses based on a Fresnelspiral diffraction grating. The flat lenses are designed by spiral-shaped Fresnel zone plates composed of one or several arms. The constructive and destructive interferences of the diffracted waves by the spiral grating result in sharp acoustic vortex beams, following the focal laws obtained in analogy with the Fresnel zone plate lenses. In addition, we show that the number of arms determines the topological charge of the vortex, allowing the precise manipulation of the acoustic wave field by flat lenses. The experimental results in the ultrasonic regime show excellent agreement with the theory and full-wave numerical simulations. A comparison with beam focusing by Archimedean spirals also showing vortex focusing is given. The results of this work may have potential applications for particle trapping, ultrasound therapy, imaging, or underwater acoustic transmitters.This work was supported by the Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through Project Nos. FIS2015-65998-C2-1 and FIS2015-65998-C2-2. N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD-2017-042.Jimenez, N.; Romero García, V.; García-Raffi, LM.; Camarena Femenia, F.; Staliunas, K. (2018). Sharp acoustic vortex focusing by Fresnel-spiral zone plates. Applied Physics Letters. 112(20):204101-1-204101-5. https://doi.org/10.1063/1.5029424S204101-1204101-511220J. Nye and M. Berry ,Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences(The Royal Society, 1974), Vol.336, pp. 165–190.Grier, D. G. (2003). A revolution in optical manipulation. Nature, 424(6950), 810-816. doi:10.1038/nature01935Volke-Sepúlveda, K., Santillán, A. O., & Boullosa, R. R. (2008). Transfer of Angular Momentum to Matter from Acoustical Vortices in Free Space. Physical Review Letters, 100(2). doi:10.1103/physrevlett.100.024302Anhäuser, A., Wunenburger, R., & Brasselet, E. (2012). Acoustic Rotational Manipulation Using Orbital Angular Momentum Transfer. Physical Review Letters, 109(3). doi:10.1103/physrevlett.109.034301Demore, C. E. M., Yang, Z., Volovick, A., Cochran, S., MacDonald, M. P., & Spalding, G. C. (2012). Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams. Physical Review Letters, 108(19). doi:10.1103/physrevlett.108.194301Hong, Z., Zhang, J., & Drinkwater, B. W. (2015). Observation of Orbital Angular Momentum Transfer from Bessel-Shaped Acoustic Vortices to Diphasic Liquid-Microparticle Mixtures. Physical Review Letters, 114(21). doi:10.1103/physrevlett.114.214301Wu, J. (1991). Acoustical tweezers. The Journal of the Acoustical Society of America, 89(5), 2140-2143. doi:10.1121/1.400907Marzo, A., Ghobrial, A., Cox, L., Caleap, M., Croxford, A., & Drinkwater, B. W. (2017). Realization of compact tractor beams using acoustic delay-lines. Applied Physics Letters, 110(1), 014102. doi:10.1063/1.4972407Marzo, A., Caleap, M., & Drinkwater, B. W. (2018). Acoustic Virtual Vortices with Tunable Orbital Angular Momentum for Trapping of Mie Particles. Physical Review Letters, 120(4). doi:10.1103/physrevlett.120.044301Shi, C., Dubois, M., Wang, Y., & Zhang, X. (2017). High-speed acoustic communication by multiplexing orbital angular momentum. Proceedings of the National Academy of Sciences, 114(28), 7250-7253. doi:10.1073/pnas.1704450114Thomas, J.-L., & Marchiano, R. (2003). Pseudo Angular Momentum and Topological Charge Conservation for Nonlinear Acoustical Vortices. Physical Review Letters, 91(24). doi:10.1103/physrevlett.91.244302Marchiano, R., & Thomas, J.-L. (2005). Synthesis and analysis of linear and nonlinear acoustical vortices. Physical Review E, 71(6). doi:10.1103/physreve.71.066616Ealo, J. L., Prieto, J. C., & Seco, F. (2011). Airborne ultrasonic vortex generation using flexible ferroelectrets. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 58(8), 1651-1657. doi:10.1109/tuffc.2011.1992Gspan, S., Meyer, A., Bernet, S., & Ritsch-Marte, M. (2004). Optoacoustic generation of a helicoidal ultrasonic beam. The Journal of the Acoustical Society of America, 115(3), 1142-1146. doi:10.1121/1.1643367Hefner, B. T., & Marston, P. L. (1999). An acoustical helicoidal wave transducer with applications for the alignment of ultrasonic and underwater systems. The Journal of the Acoustical Society of America, 106(6), 3313-3316. doi:10.1121/1.428184Jiang, X., Li, Y., Liang, B., Cheng, J., & Zhang, L. (2016). Convert Acoustic Resonances to Orbital Angular Momentum. Physical Review Letters, 117(3). doi:10.1103/physrevlett.117.034301Ye, L., Qiu, C., Lu, J., Tang, K., Jia, H., Ke, M., … Liu, Z. (2016). Making sound vortices by metasurfaces. AIP Advances, 6(8), 085007. doi:10.1063/1.4961062Naify, C. J., Rohde, C. A., Martin, T. P., Nicholas, M., Guild, M. D., & Orris, G. J. (2016). Generation of topologically diverse acoustic vortex beams using a compact metamaterial aperture. Applied Physics Letters, 108(22), 223503. doi:10.1063/1.4953075Esfahlani, H., Lissek, H., & Mosig, J. R. (2017). Generation of acoustic helical wavefronts using metasurfaces. Physical Review B, 95(2). doi:10.1103/physrevb.95.024312Jiménez, N., Picó, R., Sánchez-Morcillo, V., Romero-García, V., García-Raffi, L. M., & Staliunas, K. (2016). Formation of high-order acoustic Bessel beams by spiral diffraction gratings. Physical Review E, 94(5). doi:10.1103/physreve.94.053004Wang, T., Ke, M., Li, W., Yang, Q., Qiu, C., & Liu, Z. (2016). Particle manipulation with acoustic vortex beam induced by a brass plate with spiral shape structure. Applied Physics Letters, 109(12), 123506. doi:10.1063/1.4963185Muelas-Hurtado, R. D., Ealo, J. L., Pazos-Ospina, J. F., & Volke-Sepúlveda, K. (2018). Generation of multiple vortex beam by means of active diffraction gratings. Applied Physics Letters, 112(8), 084101. doi:10.1063/1.5016864Jiang, X., Zhao, J., Liu, S., Liang, B., Zou, X., Yang, J., … Cheng, J. (2016). Broadband and stable acoustic vortex emitter with multi-arm coiling slits. Applied Physics Letters, 108(20), 203501. doi:10.1063/1.4949337Jiménez, N., Romero-García, V., Picó, R., Cebrecos, A., Sánchez-Morcillo, V. J., Garcia-Raffi, L. M., … Staliunas, K. (2014). Acoustic Bessel-like beam formation by an axisymmetric grating. EPL (Europhysics Letters), 106(2), 24005. doi:10.1209/0295-5075/106/24005Sanchis, L., Yánez, A., Galindo, P. L., Pizarro, J., & Pastor, J. M. (2010). Three-dimensional acoustic lenses with axial symmetry. Applied Physics Letters, 97(5), 054103. doi:10.1063/1.3474616Farnow, S. A., & Auld, B. A. (1974). Acoustic Fresnel zone plate transducers. Applied Physics Letters, 25(12), 681-682. doi:10.1063/1.1655359Molerón, M., Serra-Garcia, M., & Daraio, C. (2014). Acoustic Fresnel lenses with extraordinary transmission. Applied Physics Letters, 105(11), 114109. doi:10.1063/1.4896276Jiménez, N., Romero-García, V., Picó, R., Garcia-Raffi, L. M., & Staliunas, K. (2015). Nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating embedded in water. Applied Physics Letters, 107(20), 204103. doi:10.1063/1.4935917Cox, B. T., Kara, S., Arridge, S. R., & Beard, P. C. (2007). k-space propagation models for acoustically heterogeneous media: Application to biomedical photoacoustics. The Journal of the Acoustical Society of America, 121(6), 3453. doi:10.1121/1.271740

What matters to women: a systematic scoping review to identify the processes and outcomes of antenatal care provision that are important to healthy pregnant women

BACKGROUND: Global uptake of antenatal care (ANC) varies widely and is influenced by the value women place on the service they receive. Identifying outcomes that matter to pregnant women could inform service design and improve uptake and effectiveness. OBJECTIVES: To undertake a systematic scoping review of what women want, need and value in pregnancy. SEARCH STRATEGY: Eight databases were searched (1994-2015) with no language restriction. Relevant journal contents were tracked via Zetoc. DATA COLLECTION AND ANALYSIS: An initial analytic framework was constructed with findings from 21 papers, using data-mining techniques, and then developed using meta-ethnographic approaches. The final framework was tested with 17 more papers. MAIN RESULTS: All continents except Australia were represented. A total of 1264 women were included. The final meta-theme was: Women want and need a positive pregnancy experience, including four subthemes: maintaining physical and sociocultural normality; maintaining a healthy pregnancy for mother and baby (including preventing and treating risks, illness and death); effective transition to positive labour and birth; and achieving positive motherhood (including maternal self-esteem, competence, autonomy). Findings informed a framework for future ANC provision, comprising three equally important domains: clinical practices (interventions and tests); relevant and timely information; and pyschosocial and emotional support; each provided by practitioners with good clinical and interpersonal skills within a high quality health system. CONCLUSIONS: A positive pregnancy experience matters across all cultural and sociodemographic contexts. ANC guidelines and services should be designed to deliver it, and those providing ANC services should be aware of it at each encounter with pregnant women. TWEETABLE ABSTRACT: Women around the world want ANC staff and services to help them achieve a positive pregnancy experience

Space-oriented navigation solutions with integrated sensor-suite: the I3DS H2020 project

In all orbital applications, such as on-orbit servicing and repair, rendezvous and docking, active debrisremoval (ADR), and planetary applications, such as exploration of unknown environments for scientificpurposes by means of rovers, GPS-denied navigation aspects have a very large impact on the successfuloutcome of missions. Having a sensor suite, and hence several different sensors, also requires, at the sametime, a suite of navigation algorithms able to deal with different kinds of inputs. Some of them, however,can be shared between multiple sensors, after thorough pre-processing of the raw data. Additionally, thesame kind of sensor can require two different navigation algorithms depending on the scenario. The workdescribed in this paper aims to present and critically discuss the approach to precise relative navigationsolutions with a complete suite of sensors and their performance in different space-oriented applicationscenarios.Standalone navigation filters are examined. In the case of a high-resolution camera for an orbitalscenario, the pose of a target, with respect to a chaser, can be thoroughly obtained with the aid offiducial markers. Stereo camera-based navigation is also addressed with visual odometry. In the case of astereo camera the problem of scale estimation during odometry is solved by means of triangulation. Sincethe outputs of the sensor-suite are also dense 3D point clouds, Iterative Closest Point and Histogram ofDistances (HoD) with Kalman filter approaches are analyzed, paying attention to the provision of correctsensor characterization. The results for each filter are exhaustively examined, highlighting their strengthsand the points where some improvements can be achieve

Late-transition versus smooth H(z)-deformation models for the resolution of the Hubble crisis

Gravitational transitions at low redshifts (zt < 0.1) have been recently proposed as a solution to the Hubble and growth tensions. Such transitions would naturally lead to a transition in the absolute magnitude M of type Ia supernovae (SnIa) at zt (Late M Transitions - LMT) and possibly in the dark energy equation of state parameter w (Late w − M Transitions - LwMT). Here, we compare the quality of fit of this class of models to cosmological data, with the corresponding quality of fit of the cosmological constant model (ΛCDM) and some of the best smooth H(z) deformation models (wCDM, CPL, PEDE). We also perform model selection via the Akaike Information Criterion and the Bayes factor. We use the full CMB temperature anisotropy spectrum data, the baryon acoustic oscillations (BAO) data, the Pantheon SnIa data, the SnIa absolute magnitude M as determined by Cepheid calibrators and the value of the Hubble constant H0 as determined by local SnIa calibrated using Cepheids. We find that smooth H(z) deformation models perform worse than transition models for the following reasons: 1) They have a worse fit to low-z geometric probes (BAO and SnIa data); 2) They favor values of the SnIa absolute magnitude M that are lower as compared to the value Mc obtained with local Cepheid calibrators at z < 0.01; 3) They tend to worsen the Ωm,0−σ8,0 growth tension. We also find that the w−M transition model (LwMT) does not provide a better quality of fit to cosmological data than a pure M transition model (LMT) where w is fixed to the ΛCDM value w = −1 at all redshifts. We conclude that the LMT model has significant statistical advantages over smooth late-time H(z) deformation models in addressing the Hubble crisis