2,538 research outputs found

    Cloaking resonant scatterers and tuning electron flow in graphene

    Get PDF
    We consider resonant scatterers with large scattering cross-sections in graphene that are produced by a gated disk or a vacancy, and show that a gated ring can be engineered to produce an efficient electron cloak. We also demonstrate that this same scheme can be applied to tune the direction of electron flow. Our analysis is based on a partial-wave expansion of the electronic wave-functions in the continuum approximation, described by the Dirac equation. Using a symmetrized version of the massless Dirac equation, we derive a general condition for the cloaking of a scatterer by a potential with radial symmetry. We also perform tight-binding calculations to show that our findings are robust against the presence of disorder in the gate potential.NMRP acknowledges support from EC under Graphene Flagship (Contract No. CNECT-ICT604391), the hospitality of the Instituto de Física of the UFRJ, and stimulating discussions with Bruno Amorim on the Lippamnn-Schwinger equation for Dirac electrons. TGR thanks the Brazilian agencies CNPq and FAPERJ and Brazil Science without Borders program for nancial support. FAP acknowledges CAPES (Grant No. BEX 1497/14-6) and CNPq (Grant No. 303286/2013-0) for financial suppor

    Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis

    Full text link
    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/10.1177/1468087419882500.[EN] Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the sigma -Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier-Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.The authors thank the freely shared X-ray radiography and ultra-small-angle X-ray scattering measurements performed at Argonne National Laboratory by the following authors: Daniel J. Duke, Jan Ilavsky, Katarzyna E. Matusik., Brandon A. Sforzo., Alan L. Kastengren and Christopher F. Powell. They also thankfully acknowledge the computer resources at Picasso and the technical support provided by Universidad de Malaga (UMA; RES-FI-2018-1-0039).Pandal, A.; García-Oliver, JM.; Pastor Enguídanos, JM. (2020). Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis. International Journal of Engine Research. 21(1):73-88. https://doi.org/10.1177/1468087419882500S7388211PAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84(5), 551-561. doi:10.1016/j.fuel.2004.10.009Payri, R., Salvador, F. J., Gimeno, J., & Zapata, L. D. (2008). Diesel nozzle geometry influence on spray liquid-phase fuel penetration in evaporative conditions. Fuel, 87(7), 1165-1176. doi:10.1016/j.fuel.2007.05.058Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Effects of nozzle geometry on direct injection diesel engine combustion process. Applied Thermal Engineering, 29(10), 2051-2060. doi:10.1016/j.applthermaleng.2008.10.009Payri, F., Payri, R., Salvador, F. J., & Martínez-López, J. (2012). A contribution to the understanding of cavitation effects in Diesel injector nozzles through a combined experimental and computational investigation. Computers & Fluids, 58, 88-101. doi:10.1016/j.compfluid.2012.01.005Kastengren, A. L., Powell, C. F., Wang, Y., Im, K.-S., & Wang, J. (2009). X-RAY RADIOGRAPHY MEASUREMENTS OF DIESEL SPRAY STRUCTURE AT ENGINE-LIKE AMBIENT DENSITY. Atomization and Sprays, 19(11), 1031-1044. doi:10.1615/atomizspr.v19.i11.30Pickett, L. M., Manin, J., Kastengren, A., & Powell, C. (2014). Comparison of Near-Field Structure and Growth of a Diesel Spray Using Light-Based Optical Microscopy and X-Ray Radiography. SAE International Journal of Engines, 7(2), 1044-1053. doi:10.4271/2014-01-1412Dahms, R. N., Manin, J., Pickett, L. M., & Oefelein, J. C. (2013). Understanding high-pressure gas-liquid interface phenomena in Diesel engines. Proceedings of the Combustion Institute, 34(1), 1667-1675. doi:10.1016/j.proci.2012.06.169Arienti, M., & Sussman, M. (2017). A numerical study of the thermal transient in high-pressure diesel injection. International Journal of Multiphase Flow, 88, 205-221. doi:10.1016/j.ijmultiphaseflow.2016.09.017Vallet, A., Burluka, A. A., & Borghi, R. (2001). DEVELOPMENT OF A EULERIAN MODEL FOR THE «ATOMIZATION» OF A LIQUID JET. Atomization and Sprays, 11(6), 24. doi:10.1615/atomizspr.v11.i6.20Siebers, D. L. (2008). Recent Developments on Diesel Fuel Jets Under Quiescent Conditions. Flow and Combustion in Reciprocating Engines, 257-308. doi:10.1007/978-3-540-68901-0_5Oefelein, J., Dahms, R., & Lacaze, G. (2012). Detailed Modeling and Simulation of High-Pressure Fuel Injection Processes in Diesel Engines. SAE International Journal of Engines, 5(3), 1410-1419. doi:10.4271/2012-01-1258Demoulin, F.-X., Reveillon, J., Duret, B., Bouali, Z., Desjonqueres, P., & Menard, T. (2013). TOWARD USING DIRECT NUMERICAL SIMULATION TO IMPROVE PRIMARY BREAK-UP MODELING. Atomization and Sprays, 23(11), 957-980. doi:10.1615/atomizspr.2013007439Desantes, J. M., Garcia-Oliver, J. M., Pastor, J. M., & Pandal, A. (2016). A COMPARISON OF DIESEL SPRAYS CFD MODELING APPROACHES: DDM VERSUS E-Y EULERIAN ATOMIZATION MODEL. Atomization and Sprays, 26(7), 713-737. doi:10.1615/atomizspr.2015013285Desantes, J. M., García-Oliver, J. M., Pastor, J. M., Pandal, A., Baldwin, E., & Schmidt, D. P. (2016). Coupled/decoupled spray simulation comparison of the ECN spray a condition with the -Y Eulerian atomization model. International Journal of Multiphase Flow, 80, 89-99. doi:10.1016/j.ijmultiphaseflow.2015.12.002Garcia-Oliver, J. M., Pastor, J. M., Pandal, A., Trask, N., Baldwin, E., & Schmidt, D. P. (2013). DIESEL SPRAY CFD SIMULATIONS BASED ON THE Σ-Υ EULERIAN ATOMIZATION MODEL. Atomization and Sprays, 23(1), 71-95. doi:10.1615/atomizspr.2013007198Navarro-Martinez, S. (2014). Large eddy simulation of spray atomization with a probability density function method. International Journal of Multiphase Flow, 63, 11-22. doi:10.1016/j.ijmultiphaseflow.2014.02.013Pandal, A., Pastor, J. M., García-Oliver, J. M., Baldwin, E., & Schmidt, D. P. (2016). A consistent, scalable model for Eulerian spray modeling. International Journal of Multiphase Flow, 83, 162-171. doi:10.1016/j.ijmultiphaseflow.2016.04.003Pandal, A., Payri, R., García-Oliver, J. M., & Pastor, J. M. (2017). Optimization of spray break-up CFD simulations by combining Σ-Y Eulerian atomization model with a response surface methodology under diesel engine-like conditions (ECN Spray A). Computers & Fluids, 156, 9-20. doi:10.1016/j.compfluid.2017.06.022Pandal, A., García-Oliver, J. M., Novella, R., & Pastor, J. M. (2018). A computational analysis of local flow for reacting Diesel sprays by means of an Eulerian CFD model. International Journal of Multiphase Flow, 99, 257-272. doi:10.1016/j.ijmultiphaseflow.2017.10.010Payri, R., Ruiz, S., Gimeno, J., & Martí-Aldaraví, P. (2015). Verification of a new CFD compressible segregated and multi-phase solver with different flux updates-equations sequences. Applied Mathematical Modelling, 39(2), 851-861. doi:10.1016/j.apm.2014.07.011Salvador, F. J., Gimeno, J., Pastor, J. M., & Martí-Aldaraví, P. (2014). Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model. International Journal of Multiphase Flow, 65, 108-116. doi:10.1016/j.ijmultiphaseflow.2014.06.003Demoulin, F.-X., Beau, P.-A., Blokkeel, G., Mura, A., & Borghi, R. (2007). A NEW MODEL FOR TURBULENT FLOWS WITH LARGE DENSITY FLUCTUATIONS: APPLICATION TO LIQUID ATOMIZATION. Atomization and Sprays, 17(4), 315-345. doi:10.1615/atomizspr.v17.i4.20Pandal, A., Pastor, J. M., Payri, R., Kastengren, A., Duke, D., Matusik, K., … Schmidt, D. (2017). Computational and Experimental Investigation of Interfacial Area in Near-Field Diesel Spray Simulation. SAE International Journal of Fuels and Lubricants, 10(2), 423-431. doi:10.4271/2017-01-0859Weller, H. G., Tabor, G., Jasak, H., & Fureby, C. (1998). A tensorial approach to computational continuum mechanics using object-oriented techniques. Computers in Physics, 12(6), 620. doi:10.1063/1.168744Faeth, G. M. (1983). Evaporation and combustion of sprays. Progress in Energy and Combustion Science, 9(1-2), 1-76. doi:10.1016/0360-1285(83)90005-9Pitzer, K. S., Lippmann, D. Z., Curl, R. F., Huggins, C. M., & Petersen, D. E. (1955). The Volumetric and Thermodynamic Properties of Fluids. II. Compressibility Factor, Vapor Pressure and Entropy of Vaporization1. Journal of the American Chemical Society, 77(13), 3433-3440. doi:10.1021/ja01618a002Lebas, R., Menard, T., Beau, P. A., Berlemont, A., & Demoulin, F. X. (2009). Numerical simulation of primary break-up and atomization: DNS and modelling study. International Journal of Multiphase Flow, 35(3), 247-260. doi:10.1016/j.ijmultiphaseflow.2008.11.005Duret, B., Reveillon, J., Menard, T., & Demoulin, F. X. (2013). Improving primary atomization modeling through DNS of two-phase flows. International Journal of Multiphase Flow, 55, 130-137. doi:10.1016/j.ijmultiphaseflow.2013.05.004Gimeno, J., Bracho, G., Martí-Aldaraví, P., & Peraza, J. E. (2016). Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part I: Inert atmosphere. Energy Conversion and Management, 126, 1146-1156. doi:10.1016/j.enconman.2016.07.077Kastengren, A., Ilavsky, J., Viera, J. P., Payri, R., Duke, D. J., Swantek, A., … Powell, C. F. (2017). Measurements of droplet size in shear-driven atomization using ultra-small angle x-ray scattering. International Journal of Multiphase Flow, 92, 131-139. doi:10.1016/j.ijmultiphaseflow.2017.03.005Kastengren, A. L., Tilocco, F. Z., Powell, C. F., Manin, J., Pickett, L. M., Payri, R., & Bazyn, T. (2012). ENGINE COMBUSTION NETWORK (ECN): MEASUREMENTS OF NOZZLE GEOMETRY AND HYDRAULIC BEHAVIOR. Atomization and Sprays, 22(12), 1011-1052. doi:10.1615/atomizspr.2013006309Matusik, K. E., Duke, D. J., Kastengren, A. L., Sovis, N., Swantek, A. B., & Powell, C. F. (2017). High-resolution X-ray tomography of Engine Combustion Network diesel injectors. International Journal of Engine Research, 19(9), 963-976. doi:10.1177/1468087417736985Payri, R., Gimeno, J., Cuisano, J., & Arco, J. (2016). Hydraulic characterization of diesel engine single-hole injectors. Fuel, 180, 357-366. doi:10.1016/j.fuel.2016.03.083Naber, J., & Siebers, D. L. (1996). Effects of Gas Density and Vaporization on Penetration and Dispersion of Diesel Sprays. SAE Technical Paper Series. doi:10.4271/960034Pope, S. B. (1978). An explanation of the turbulent round-jet/plane-jet anomaly. AIAA Journal, 16(3), 279-281. doi:10.2514/3.7521Battistoni, M., Magnotti, G. M., Genzale, C. L., Arienti, M., Matusik, K. E., Duke, D. J., … Marti-Aldaravi, P. (2018). Experimental and Computational Investigation of Subcritical Near-Nozzle Spray Structure and Primary Atomization in the Engine Combustion Network Spray D. SAE International Journal of Fuels and Lubricants, 11(4), 337-352. doi:10.4271/2018-01-0277Chesnel, J., Reveillon, J., Menard, T., & Demoulin, F.-X. (2011). LARGE EDDY SIMULATION OF LIQUID JET ATOMIZATION. Atomization and Sprays, 21(9), 711-736. doi:10.1615/atomizspr.2012003740Devassy, B. M., Habchi, C., & Daniel, E. (2015). ATOMIZATION MODELLING OF LIQUID JETS USING A TWO-SURFACE-DENSITY APPROACH. Atomization and Sprays, 25(1), 47-80. doi:10.1615/atomizspr.2014011350García-Oliver, J. M., Malbec, L.-M., Toda, H. B., & Bruneaux, G. (2017). A study on the interaction between local flow and flame structure for mixing-controlled Diesel sprays. Combustion and Flame, 179, 157-171. doi:10.1016/j.combustflame.2017.01.023Han, D., & Mungal, M. . (2001). Direct measurement of entrainment in reacting/nonreacting turbulent jets. Combustion and Flame, 124(3), 370-386. doi:10.1016/s0010-2180(00)00211-xHill, B. J. (1972). Measurement of local entrainment rate in the initial region of axisymmetric turbulent air jets. Journal of Fluid Mechanics, 51(4), 773-779. doi:10.1017/s0022112072001351Post, S., Iyer, V., & Abraham, J. (1999). A Study of Near-Field Entrainment in Gas Jets and Sprays Under Diesel Conditions. Journal of Fluids Engineering, 122(2), 385-395. doi:10.1115/1.48326

    Design of energy control method for three-phase buck-type rectifier with very demanding load steps

    Get PDF
    Conventional three-phase rectifiers are controlled to achieve good power factor and low THD in the input. In the case of pulsating power loads, the fast dynamic response implies that the load pulses are reflected in the generator. These pulsating loads affect the life time operation of the generator, especially when it is not oversized (that is the case in aircraft applications). In order to smooth the power demanded from the generator, it is preferable to reduce the bandwidth of the controller to the rectifier but it affects its stability due to the fact that the right half plane pole given by the negative impedance of a constant power load requires high bandwidth control loop to compensate it. In this paper, an energy control method is proposed to employ the energy stored in the output capacitor of the rectifier to control the amount of power demanded through the rectifier. In such a way the bandwidth restriction for stability is eliminated and the bandwidth of the loop can be set slow enough to ensure smooth power demanded from the generator

    The largest European theropod dinosaurs: remains of a gigantic megalosaurid and giant theropod tracks from the Kimmeridgian of Asturias, Spain

    Get PDF
    The Kimmeridgian Vega, Terenes and Lastres formations of Asturias have yielded a rich vertebrate fauna, represented by both abundant tracks and osteological remains. However, skeletal remains of theropod dinosaurs are rare, and the diversity of theropod tracks has only partially been documented in the literature. Here we describe the only non-dental osteological theropod remain recovered so far, an isolated anterior caudal vertebra, as well as the largest theropod tracks found. The caudal vertebra can be shown to represent a megalosaurine megalosaurid and represents the largest theropod skeletal remain described from Europe so far. The tracks are also amongst the largest theropod footprints reported from any setting and can be assigned to two different morphotypes, one being characterized by its robustness and a weak mesaxony, and the other characterized by a strong mesaxony, representing a more gracile trackmaker. We discuss the recently proposed distinction between robust and gracile large to giant theropod tracks and their possible trackmakers during the Late Jurassic-Berriasian. In the absence of complete pedal skeletons of most basal tetanurans, the identity of the maker of Jurassic giant theropod tracks is difficult to establish. However, the notable robustness of megalosaurine megalosaurids fits well with the described robust morphotypes, whereas more slender large theropod tracks might have been made by a variety of basal tetanurans, including allosaurids, metriocanthosaurids or afrovenatorine megalosaurids, or even exceptionally large ceratosaurs. Concerning osteological remains of large theropods from the Late Jurassic of Europe, megalosaurids seem to be more abundant than previously recognized and occur in basically all Jurassic deposits where theropod remains have been found, whereas allosauroids seem to be represented by allosaurids in Western Europe and metriacanthosaurids in more eastern areas. Short-term fluctuations in sea level might have allowed exchange of large theropods between the islands that constituted Europe during the Late Jurassic

    Metoprolol blunts the time-dependent progression of infarct size.

    Get PDF
    Early metoprolol administration protects against myocardial ischemia-reperfusion injury, but its effect on infarct size progression (ischemic injury) is unknown. Eight groups of pigs (total n = 122) underwent coronary artery occlusion of varying duration (20, 25, 30, 35, 40, 45, 50, or 60 min) followed by reperfusion. In each group, pigs were randomized to i.v. metoprolol (0.75 mg/kg) or vehicle (saline) 20 min after ischemia onset. The primary outcome measure was infarct size (IS) on day7 cardiac magnetic resonance (CMR) normalized to area at risk (AAR, measured by perfusion computed tomography [CT] during ischemia). Metoprolol treatment reduced overall mortality (10% vs 26%, p = 0.03) and the incidence and number of primary ventricular fibrillations during infarct induction. In controls, IS after 20-min ischemia was ≈ 5% of the area AAR. Thereafter, IS progressed exponentially, occupying almost all the AAR after 35 min of ischemia. Metoprolol injection significantly reduced the slope of IS progression (p = 0.004 for final IS). Head-to-head comparison (metoprolol treated vs vehicle treated) showed statistically significant reductions in IS at 30, 35, 40, and 50-min reperfusion. At 60-min reperfusion, IS was 100% of AAR in both groups. Despite more prolonged ischemia, metoprolol-treated pigs reperfused at 50 min had smaller infarcts than control pigs undergoing ischemia for 40 or 45 min and similar-sized infarcts to those undergoing 35-min ischemia. Day-45 LVEF was higher in metoprolol-treated vs vehicle-treated pigs (41.6% vs 36.5%, p = 0.008). In summary, metoprolol administration early during ischemia attenuates IS progression and reduces the incidence of primary ventricular fibrillation. These data identify metoprolol as an intervention ideally suited to the treatment of STEMI patients identified early in the course of infarction and requiring long transport times before primary angioplasty.This study received funding from the Ministry of Science and Innovation (“RETOS 2019” Grant no. PID2019-107332RB-I00), from the Instituto de Salud Carlos III (ISCIII; PI16/02110) and the European Regional Development Fund (ERDF) “A way of making Europe” (# AC16/00021), and from the Spanish Society of Cardiology through a 2017 Translational Research grant. BI has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC-Consolidator Grant agreement no. 819775). M.L received support from a 2015 Severo Ochoa CNIC intramural grant. X.R. received support from the SEC-CNIC CARDIOJOVEN fellowship program. R.F-J is a recipient of funding from the Carlos III Institute of Health-Fondo de Investigacion Sanitaria (PI19/01704) and has received funding from the European Union Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No 707642. EO is recipient of funds from Programa de Atracción de Talento (2017-T1/BMD-5185) of Comunidad de Madrid. The CNIC is supported by the ISCIII, the Ministerio de Ciencia e Innovación (MICINN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

    Fabrication of near-zero thermal expansion of fully dense beta-eucryptite ceramics by microwave sintering

    Full text link
    Microwave heating is proposed as non-conventional technique for the sintering of optimal lithium aluminosilicate compositions of β-eucryptite system. The coefficient of thermal expansion and mechanical properties of the sintered samples has been studied under the influence of microwave heating. The ad hoc synthesized β-eucryptite together with the microwave sintering technique developed in this work open the opportunity to produce breakthrough materials with low or negative coefficient of thermal expansion and excellent mechanical properties, as a Young s modulus of 110 GPa. The combination of rapid heating with low energy applied by the microwave technology (eco-friendly process) and the dramatic reduction in cycle time allows densification without glass phase formation. Results of the coefficient of thermal expansion of the β-eucryptite ceramics presented here under cryogenic conditions will be of value, for example, in the future design of new composite materials for space applicationsThe authors would like to thank Dr. Emilio Rayon for performing the nanoindentation analysis in the Materials Technology institute (ITM) of the Polytechnic University of Valencia (UPV) and your financial support received of UPV under Projects SP20120621 and SP20120677 and Spanish Government through the Project MONIDIEL (TEC2008-04109). A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for a Juan de la Cierva contract (JCI-2011-10498) and SCSIE of the University of Valencia.Benavente Martínez, R.; Borrell Tomás, MA.; Salvador Moya, MD.; Garcia-Moreno, O.; Penaranda-Foix, FL.; Catalá Civera, JM. (2014). Fabrication of near-zero thermal expansion of fully dense beta-eucryptite ceramics by microwave sintering. Ceramics International. 40(1):935-941. https://doi.org/10.1016/j.ceramint.2013.06.089S93594140

    PDBe: improved accessibility of macromolecular structure data from PDB and EMDB

    Get PDF
    © 2015 The Authors. Published by OUP. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1093/nar/gkv1047The Protein Data Bank in Europe (http://pdbe.org) accepts and annotates depositions of macromolecular structure data in the PDB and EMDB archives and enriches, integrates and disseminates structural information in a variety of ways. The PDBe website has been redesigned based on an analysis of user requirements, and now offers intuitive access to improved and value-added macromolecular structure information. Unique value-added information includes lists of reviews and research articles that cite or mention PDB entries as well as access to figures and legends from full-text open-access publications that describe PDB entries. A powerful new query system not only shows all the PDB entries that match a given query, but also shows the 'best structures' for a given macromolecule, ligand complex or sequence family using data-quality information from the wwPDB validation reports. A PDBe RESTful API has been developed to provide unified access to macromolecular structure data available in the PDB and EMDB archives as well as value-added annotations, e.g. regarding structure quality and up-to-date cross-reference information from the SIFTS resource. Taken together, these new developments facilitate unified access to macromolecular structure data in an intuitive way for non-expert users and support expert users in analysing macromolecular structure data.The Wellcome Trust [88944, 104948]; UK Biotechnology and Biological Sciences Research Council [BB/J007471/1, BB/K016970/1, BB/M013146/1, BB/M011674/1]; National Institutes of Health [GM079429]; UK Medical Research Council [MR/L007835/1]; European Union [284209]; CCP4; European Molecular Biology Laboratory (EMBL). Funding for open access charge: The Wellcome Trust.Published versio

    Effective Lagrangian approach to neutrinoless double beta decay and neutrino masses

    Get PDF
    Neutrinoless double beta (0νββ0\nu\beta\beta) decay can in general produce electrons of either chirality, in contrast with the minimal Standard Model (SM) extension with only the addition of the Weinberg operator, which predicts two left-handed electrons in the final state. We classify the lepton number violating (LNV) effective operators with two leptons of either chirality but no quarks, ordered according to the magnitude of their contribution to \znbb decay. We point out that, for each of the three chirality assignments, eLeL,eLeRe_Le_L, e_Le_R and eReRe_Re_R, there is only one LNV operator of the corresponding type to lowest order, and these have dimensions 5, 7 and 9, respectively. Neutrino masses are always induced by these extra operators but can be delayed to one or two loops, depending on the number of RH leptons entering in the operator. Then, the comparison of the 0νββ0\nu\beta\beta decay rate and neutrino masses should indicate the effective scenario at work, which confronted with the LHC searches should also eventually decide on the specific model elected by nature. We also list the SM additions generating these operators upon integration of the heavy modes, and discuss simple realistic examples of renormalizable theories for each case.Comment: Accepted for publication. Few misprints corrected and new references adde

    Forebrain-specific, conditional silencing of Staufen2 alters synaptic plasticity, learning, and memory in rats

    Get PDF
    Background: Dendritic messenger RNA (mRNA) localization and subsequent local translation in dendrites critically contributes to synaptic plasticity and learning and memory. Little is known, however, about the contribution of RNA-binding proteins (RBPs) to these processes in vivo. Results: To delineate the role of the double-stranded RBP Staufen2 (Stau2), we generate a transgenic rat model, in which Stau2 expression is conditionally silenced by Cre-inducible expression of a microRNA (miRNA) targeting Stau2 mRNA in adult forebrain neurons. Known physiological mRNA targets for Stau2, such as RhoA, Complexin 1, and Rgs4 mRNAs, are found to be dysregulated in brains of Stau2-deficient rats. In vivo electrophysiological recordings reveal synaptic strengthening upon stimulation, showing a shift in the frequency-response function of hippocampal synaptic plasticity to favor long-term potentiation and impair long-term depression in Stau2-deficient rats. These observations are accompanied by deficits in hippocampal spatial working memory, spatial novelty detection, and in tasks investigating associative learning and memory. Conclusions: Together, these experiments reveal a critical contribution of Stau2 to various forms of synaptic plasticity including spatial working memory and cognitive management of new environmental information. These findings might contribute to the development of treatments for conditions associated with learning and memory deficits

    A Neutrophil Timer Coordinates Immune Defense and Vascular Protection

    Get PDF
    Neutrophils eliminate pathogens efficiently but can inflict severe damage to the host if they over-activate within blood vessels. It is unclear how immunity solves the dilemma of mounting an efficient anti-microbial defense while preserving vascular health. Here, we identify a neutrophil-intrinsic program that enabled both. The gene Bmal1 regulated expression of the chemokine CXCL2 to induce chemokine receptor CXCR2-dependent diurnal changes in the transcriptional and migratory properties of circulating neutrophils. These diurnal alterations, referred to as neutrophil aging, were antagonized by CXCR4 (C-X-C chemokine receptor type 4) and regulated the outer topology of neutrophils to favor homeostatic egress from blood vessels at night, resulting in boosted anti-microbial activity in tissues. Mice engineered for constitutive neutrophil aging became resistant to infection, but the persistence of intravascular aged neutrophils predisposed them to thrombo-inflammation and death. Thus, diurnal compartmentalization of neutrophils, driven by an internal timer, coordinates immune defense and vascular protection.We thank all members of the Hidalgo Lab for discussion and insightful comments; J.M. Ligos, R. Nieto, and M. Viton for help with sorting and cytometric analyses; I. Ortega and E. Santos for animal husbandry; D. Rico, M.J. Gomez, C. Torroja, and F. Sanchez-Cabo for insightful comments and help with transcriptomic analyses; V. Labrador, E. Arza, A.M. Santos, and the Microscopy Unit of the CNIC for help with microscopy; S. Aznar-Benitah, U. Albrecht, Q.-J. Meng, B. Staels, and H. Duez for the generous gift of mice; J.A. Enriquez and J. Avila for scientific insights; and J.M. Garcia and A. Diez de la Cortina for art. This study was supported by Intramural grants from A* STAR to L.G.N., BES-2013-065550 to J.M.A., BES-2010-032828 to M.C.-A, and JCI-2012-14147 to L.A.W (all from Ministerio de Economia, Industria y Competitividad; MEIC). Additional MEIC grants were SAF2014-61993-EXP to C.L.-R.; SAF2015-68632-R to M.A.M. and SAF-2013-42920R and SAF2016-79040Rto D.S. D.S. also received 635122-PROCROP H2020 from the European Commission and ERC CoG 725091 from the European Research Council (ERC). ERC AdG 692511 PROVASC from the ERC and SFB1123-A1 from the Deutsche Forschungsgemeinschaft were given to C.W.; MHA VD1.2/81Z1600212 from the German Center for Cardiovascular Research (DZHK) was given to C.W. and O.S.; SFB1123-A6 was given to O.S.; SFB914-B08 was given to O.S. and C.W.; and INST 211/604-2, ZA 428/12-1, and ZA 428/13-1 were given to A.Z. This study was also supported by PI12/00494 from Fondo de Investigaciones Sanitarias (FIS) to C.M.; PI13/01979, Cardiovascular Network grant RD 12/0042/0054, and CIBERCV to B.I.; SAF2015-65607-R, SAF2013-49662-EXP, and PCIN-2014-103 from MEIC; and co-funding by Fondo Europeo de Desarrollo Regional (FEDER) to A.H. The CNIC is supported by the MEIC and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505).S
    corecore