Why Be Regular? Part I

We provide a novel perspective on "regularity" as a property of representations of the Weyl algebra. We first critique a proposal by Halvorson [2004, "Complementarity of representations in quantum mechanics", Studies in History and Philosophy of Modern Physics 35(1), pp. 45--56], who argues that the non-regular "position" and "momentum" representations of the Weyl algebra demonstrate that a quantum mechanical particle can have definite values for position or momentum, contrary to a widespread view. We how that there are obstacles to such an intepretation of non-regular representations. In Part II, we propose a justification for focusing on regular representations, pace Halvorson, by drawing on algebraic methods

Why Be Regular? Part I

We provide a novel perspective on "regularity" as a property of representations of the Weyl algebra. We first critique a proposal by Halvorson [2004, "Complementarity of representations in quantum mechanics", Studies in History and Philosophy of Modern Physics 35(1), pp. 45--56], who argues that the non-regular "position" and "momentum" representations of the Weyl algebra demonstrate that a quantum mechanical particle can have definite values for position or momentum, contrary to a widespread view. We how that there are obstacles to such an intepretation of non-regular representations. In Part II, we propose a justification for focusing on regular representations, pace Halvorson, by drawing on algebraic methods

Cycle-to-cycle combustion variability modelling in spark ignited engines for control purposes

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419885754.[EN] A control-oriented model of spark ignition combustion is presented. The model makes use of avaliable signals, such as spark advance, air mass, intake pressure, and lambda, to characterize not only the average combustion evolution but also the cycle-to-cycle variability. The conventional turbulent flame propagation model with two states, namely entrained mass and burnt mass, is improved by look-up tables at some parameters, and the cycle-to-cycle variability is estimated by propagation of an exogenous noise with a normal probabilistic distribution at the turbulent and laminar flame speed, which intends to simulate the unknowns at turbulent flow, temperature distribution, or initial kernel distribution. The model is able to estimate which is the expected variability during the combustion evolution and might be used online for characterizing the time response of closed-loop control actions or it can be used offline to improve the control strategies without large experimental test campaigns. Experimental data from a four-stroke commercial engine was used for calibration and validation purposes, demonstrating the capabilities of the model in steady and transient conditions.The authors appreciate the technical support and the clues given by J. Israel Sanchez for the model development and also acknowledge the support of Spanish Ministerio de Economia, Industria y Competitividad through project TRA2016-78717-R.Pla Moreno, B.; De La Morena, J.; Bares-Moreno, P.; Jimenez, IA. (2020). Cycle-to-cycle combustion variability modelling in spark ignited engines for control purposes. International Journal of Engine Research. 21(8):1398-1411. https://doi.org/10.1177/1468087419885754S13981411218Wang, S., Prucka, R., Zhu, Q., Prucka, M., & Dourra, H. (2016). A Real-Time Model for Spark Ignition Engine Combustion Phasing Prediction. SAE International Journal of Engines, 9(2), 1180-1190. doi:10.4271/2016-01-0819Kim, N., Ko, I., & Min, K. (2018). Development of a zero-dimensional turbulence model for a spark ignition engine. International Journal of Engine Research, 20(4), 441-451. doi:10.1177/1468087418760406Wang, S., Zhu, Q., Prucka, R., Prucka, M., & Dourra, H. (2015). Input Adaptation for Control Oriented Physics-Based SI Engine Combustion Models Based on Cylinder Pressure Feedback. SAE International Journal of Engines, 8(4), 1463-1471. doi:10.4271/2015-01-0877Zhen, X., Wang, Y., Xu, S., Zhu, Y., Tao, C., Xu, T., & Song, M. (2012). The engine knock analysis – An overview. Applied Energy, 92, 628-636. doi:10.1016/j.apenergy.2011.11.079Bares, P., Selmanaj, D., Guardiola, C., & Onder, C. (2018). Knock probability estimation through an in-cylinder temperature model with exogenous noise. Mechanical Systems and Signal Processing, 98, 756-769. doi:10.1016/j.ymssp.2017.05.033Zhang, Y., Shen, X., Wu, Y., & Shen, T. (2019). On-board knock probability map learning–based spark advance control for combustion engines. International Journal of Engine Research, 20(10), 1073-1088. doi:10.1177/1468087419858026Spelina, J. M., Peyton Jones, J. C., & Frey, J. (2014). Stochastic simulation and analysis of a classical knock controller. International Journal of Engine Research, 16(3), 461-473. doi:10.1177/1468087414551073Neumann, D., Jörg, C., Peschke, N., Schaub, J., & Schnorbus, T. (2017). Real-time capable simulation of diesel combustion processes for HiL applications. International Journal of Engine Research, 19(2), 214-229. doi:10.1177/1468087417726226Pipitone, E. (2008). A Comparison Between Combustion Phase Indicators for Optimal Spark Timing. Journal of Engineering for Gas Turbines and Power, 130(5). doi:10.1115/1.2939012Bares, P., Selmanaj, D., Guardiola, C., & Onder, C. (2018). A new knock event definition for knock detection and control optimization. Applied Thermal Engineering, 131, 80-88. doi:10.1016/j.applthermaleng.2017.11.138Peyton Jones, J. C., Spelina, J. M., & Frey, J. (2013). Optimizing knock thresholds for improved knock control. International Journal of Engine Research, 15(1), 123-132. doi:10.1177/1468087413482321Emiliano, P. (2014). Spark Ignition Feedback Control by Means of Combustion Phase Indicators on Steady and Transient Operation. Journal of Dynamic Systems, Measurement, and Control, 136(5). doi:10.1115/1.4026966Zhu, Q., Prucka, R., Wang, S., Prucka, M., & Dourra, H. (2016). Model-Based Optimal Combustion Phasing Control Strategy for Spark Ignition Engines. SAE International Journal of Engines, 9(2), 1170-1179. doi:10.4271/2016-01-0818Zhang, Y., & Shen, T. (2017). Cylinder pressure based combustion phase optimization and control in spark-ignited engines. Control Theory and Technology, 15(2), 83-91. doi:10.1007/s11768-017-6175-1Zhang, Y., Shen, X., & Shen, T. (2018). A survey on online learning and optimization for spark advance control of SI engines. Science China Information Sciences, 61(7). doi:10.1007/s11432-017-9377-7Corti, E., Forte, C., Mancini, G., & Moro, D. (2014). Automatic Combustion Phase Calibration With Extremum Seeking Approach. Journal of Engineering for Gas Turbines and Power, 136(9). doi:10.1115/1.4027188Corti, E., Cerofolini, A., Cavina, N., Forte, C., Mancini, G., Moro, D., … Ravaglioli, V. (2014). Automatic Calibration of Control Parameters based on Merit Function Spectral Analysis. Energy Procedia, 45, 919-928. doi:10.1016/j.egypro.2014.01.097Popovic, D., Jankovic, M., Magner, S., & Teel, A. R. (2006). Extremum seeking methods for optimization of variable cam timing engine operation. IEEE Transactions on Control Systems Technology, 14(3), 398-407. doi:10.1109/tcst.2005.863660Hellstrom, E., Lee, D., Jiang, L., Stefanopoulou, A. G., & Yilmaz, H. (2013). On-Board Calibration of Spark Timing by Extremum Seeking for Flex-Fuel Engines. IEEE Transactions on Control Systems Technology, 21(6), 2273-2279. doi:10.1109/tcst.2012.2236093Pera, C., Chevillard, S., & Reveillon, J. (2013). Effects of residual burnt gas heterogeneity on early flame propagation and on cyclic variability in spark-ignited engines. Combustion and Flame, 160(6), 1020-1032. doi:10.1016/j.combustflame.2013.01.009Zhao, L., Moiz, A. A., Som, S., Fogla, N., Bybee, M., Wahiduzzaman, S., … Kodavasal, J. (2017). Examining the role of flame topologies and in-cylinder flow fields on cyclic variability in spark-ignited engines using large-eddy simulation. International Journal of Engine Research, 19(8), 886-904. doi:10.1177/1468087417732447Pera, C., Knop, V., & Reveillon, J. (2015). Influence of flow and ignition fluctuations on cycle-to-cycle variations in early flame kernel growth. Proceedings of the Combustion Institute, 35(3), 2897-2905. doi:10.1016/j.proci.2014.07.037Schiffmann, P., Reuss, D. L., & Sick, V. (2017). Empirical investigation of spark-ignited flame-initiation cycle-to-cycle variability in a homogeneous charge reciprocating engine. International Journal of Engine Research, 19(5), 491-508. doi:10.1177/1468087417720558Galloni, E. (2009). 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Quantum teleportation on a photonic chip

Quantum teleportation is a fundamental concept in quantum physics which now finds important applications at the heart of quantum technology including quantum relays, quantum repeaters and linear optics quantum computing (LOQC). Photonic implementations have largely focussed on achieving long distance teleportation due to its suitability for decoherence-free communication. Teleportation also plays a vital role in the scalability of photonic quantum computing, for which large linear optical networks will likely require an integrated architecture. Here we report the first demonstration of quantum teleportation in which all key parts - entanglement preparation, Bell-state analysis and quantum state tomography - are performed on a reconfigurable integrated photonic chip. We also show that a novel element-wise characterisation method is critical to mitigate component errors, a key technique which will become increasingly important as integrated circuits reach higher complexities necessary for quantum enhanced operation.Comment: Originally submitted version - refer to online journal for accepted manuscript; Nature Photonics (2014

Broken symmetry states and divergent resistance in suspended bilayer graphene

Graphene [1] and its bilayer have generated tremendous excitement in the physics community due to their unique electronic properties [2]. The intrinsic physics of these materials, however, is partially masked by disorder, which can arise from various sources such as ripples [3] or charged impurities [4]. Recent improvements in quality have been achieved by suspending graphene flakes [5,6], yielding samples with very high mobilities and little charge inhomogeneity. Here we report the fabrication of suspended bilayer graphene devices with very little disorder. We observe fully developed quantized Hall states at magnetic fields of 0.2 T, as well as broken symmetry states at intermediate filling factors $\nu = 0$, $\pm 1$, $\pm 2$ and $\pm 3$. The devices exhibit extremely high resistance in the $\nu = 0$ state that grows with magnetic field and scales as magnetic field divided by temperature. This resistance is predominantly affected by the perpendicular component of the applied field, indicating that the broken symmetry states arise from many-body interactions.Comment: 23 pages, including 4 figures and supplementary information; accepted to Nature Physic

Can we continue research in splenectomized dogs? Mycoplasma haemocanis: Old problem - New insight

We report the appearance of a Mycoplasma haemocanis infection in laboratory dogs, which has been reported previously, yet, never before in Europe. Outbreak of the disease was triggered by a splenectomy intended to prepare the dogs for a hemorrhagic shock study. The clinical course of the dogs was dramatic including anorexia and hemolytic anemia. Treatment included allogeneic transfusion, prednisone, and oxytetracycline. Systematic follow-up (n=12, blood smears, antibody testing and specific polymerase chain reaction) gives clear evidence that persistent eradication of M. haemocanis is unlikely. We, therefore, had to abandon the intended shock study. In the absence of effective surveillance and screening for M. haemocanis, the question arises whether it is prudent to continue shock research in splenectomized dogs. Copyright (C) 2004 S. Karger AG, Basel

Genomic Expansion of Magnetotactic Bacteria Reveals an Early Common Origin of Magnetotaxis with Lineage-specific Evolution

The origin and evolution of magnetoreception, which in diverse prokaryotes and protozoa is known as magnetotaxis and enables these microorganisms to detect Earth’s magnetic field for orientation and navigation, is not well understood in evolutionary biology. The only known prokaryotes capable of sensing the geomagnetic field are magnetotactic bacteria (MTB), motile microorganisms that biomineralize intracellular, membrane-bounded magnetic single-domain crystals of either magnetite (Fe3O4) or greigite (Fe3S4) called magnetosomes. Magnetosomes are responsible for magnetotaxis in MTB. Here we report the first large-scale metagenomic survey of MTB from both northern and southern hemispheres combined with 28 genomes from uncultivated MTB. These genomes expand greatly the coverage of MTB in the Proteobacteria, Nitrospirae, and Omnitrophica phyla, and provide the first genomic evidence of MTB belonging to the Zetaproteobacteria and “Candidatus Lambdaproteobacteria” classes. The gene content and organization of magnetosome gene clusters, which are physically grouped genes that encode proteins for magnetosome biosynthesis and organization, are more conserved within phylogenetically similar groups than between different taxonomic lineages. Moreover, the phylogenies of core magnetosome proteins form monophyletic clades. Together, these results suggest a common ancient origin of iron-based (Fe3O4 and Fe3S4) magnetotaxis in the domain Bacteria that underwent lineage-specific evolution, shedding new light on the origin and evolution of biomineralization and magnetotaxis, and expanding significantly the phylogenomic representation of MTB

Gravitational sliding of the Mt. Etna massif along a sloping basement

Geological field evidence and laboratory modelling indicate that volcanoes constructed on slopes slide downhill. If this happens on an active volcano, then the movement will distort deformation data and thus potentially compromise interpretation. Our recent GPS measurements demonstrate that the entire edifice of Mt. Etna is sliding to the ESE, the overall direction of slope of its complex, rough sedimentary basement. We report methods of discriminating the sliding vector from other deformation processes and of measuring its velocity, which averaged 14 mm year−1 during four intervals between 2001 and 2012. Though sliding of one sector of a volcano due to flank instability is widespread and well-known, this is the first time basement sliding of an entire active volcano has been directly observed. This is important because the geological record shows that such sliding volcanoes are prone to devastating sector collapse on the downslope side, and whole volcano migration should be taken into account when assessing future collapse hazard. It is also important in eruption forecasting, as the sliding vector needs to be allowed for when interpreting deformation events that take place above the sliding basement within the superstructure of the active volcano, as might occur with dyke intrusion or inflation/deflation episodes

Dynamic in vitro measurement of patellar movement after total knee arthroplasty: an in vitro study

BACKGROUND: Changing the kinematic behaviour of patellar movement could be one of the reasons for anterior knee pain after implantation of a total knee arthroplasty (TKA). The aim of the current study was to measure the potential influence on patellar kinematics of patellar resurfacing during TKA. METHODS: Patellar movement before and after TKA with and without patellar resurfacing was measured under dynamic conditions in an in vitro cadaver simulation. Physiologic Musculus quadriceps forces were applied to five physiologic human knee specimens undergoing simulated isokinetic extension motions, patellar movement was measured using an ultrasonic measurement system. Thereafter, the Interax(® )I.S.A.-prosthesis system was implanted without and with resurfacing the patella, and patellar movement was again measured. RESULTS: The physiologic patella center moved on a semilunar path up to 6.4 mm (SD 6.4 mm) medially during extension. After TKA, the unresurfaced patella showed significantly less medial translation (p = 0.04) than the resurfaced patella. Subsequent resurfacing of the patella then resulted in a return to mediolateral positioning of the patella similar to the physiological case, whereas the resurfaced patella tilted up to twice as much as physiologic. CONCLUSION: The results of this study suggest that resurfacing of the patella during TKA can result in a restoration of the physiologic mediolateral shift of the patellofemoral joint while angulation of the patella remains unphysiologic