633 research outputs found

    Excited lepton triplet contribution to electroweak observables at one loop level

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    In this paper, we present the one-loop radiative corrections to the electroweak precision observable ρ com ing from the IW = 1 multiplet excited leptons. We have cal culated the couplings of the exotic lepton triplet to the vector bosons and ordinary leptons using the effective Lagrangian approach. These couplings are then used to estimate the excited lepton triplet contribution to the ρ parameter. The mass degenerate excited lepton contribution to ρ is small and can be neglected. However, if the excited leptons are non degenerate, their contribution can be large which can result in more stringent constraints on the excited fermion parameter space compared to the constraints from present experimental searches and perturbative unitarity conditionM. Rehman and M. E. Gomez wish to thank the Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Perugia, for kind hospitality and support for collaboration visits during the early and final stages of this work. The research of M.E.G. was supported by the Spanish MINECO, under grants FPA2017-86380 and PID2019- 107844GB-C2

    Compressibility and structural stability of ultra-incompressible bimetallic interstitial carbides and nitrides

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    We have investigated by means of high-pressure x-ray diffraction the structural stability of Pd2Mo3N, Ni2Mo3C0.52N0.48, Co3Mo3C0.62N0.38, and Fe3Mo3C. We have found that they remain stable in their ambient-pressure cubic phase at least up to 48 GPa. All of them have a bulk modulus larger than 330 GPa, being the least compressible material Fe3Mo3C, B0 = 374(3) GPa. In addition, apparently a reduction of compressibility is detected as the carbon content increased. The equation of state for each material is determined. A comparison with other refractory materials indicates that interstitial nitrides and carbides behave as ultra-incompressible materials.Comment: 14 pages, 3 figures, 1 tabl

    Upconverting Carbon Nanodots from EDTA as Near-Infrared Activated Phototheranostic Agents

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    This work describes the synthesis of nitrogen-doped carbon nanodots (CNDs) synthesized from ethylene diamine tetra acetic acid (EDTA) as a precursor and their application as luminescent agents with a dual-mode theranostic role as near-infrared (NIR) triggered imaging and photodynamic therapy agents. Interestingly, these fluorescent CNDs are more rapidly and selectively internalized in tumor cells and exhibit no cytotoxicity until remotely activated with a NIR illumination source. These CNDs are excellent candidates for photo-theranostic purposes, i.e.: simultaneous imaging and therapy can be carried out on cancer cells using their luminescent properties and the in situ generation of reactive oxidative species (ROS) upon excitation in the NIR range. In the presence of CNDs NIR remote activation induces the in vitro killing of U251 MG cells. Through the use of flow imaging cytometry we have been able to successfully map and quantify the different type of cell deaths induced by the presence of intracellular superoxide anions (¿O2-) and hydrogen peroxide (H2O2) ROS species generated in situ upon NIR irradiation

    Efecto de posibles mitovirus en el crecimiento in vitro de aislados de Gremmeniella abietina bajo diferentes condiciones de laboratorio

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    Mitoviruses have been found in several forest pathogens (i.e. Cryphonectria parasitica, Gremmeniella abietina), and because they have been shown to reduce the virulence of host fungi there is a growing interest in studying their use as a biocontrol. This study was carried out to test the effect of temperature (5°C, 15°C, 25°C and 35°C), pH (4, 5, 7 and 9) and osmotic potential (–0.6, –1.2, –1.8 and –2.4 MPa) on the mycelial growth of seven G. abietina isolates under controlled laboratory conditions. Four of the isolates hosted mitoviruses and three of them did not. During the experiment, mycelial growth was recorded every week for a period of 8 weeks. Results showed no differences in growth behavior between mitovirus infected and non-infected isolates when placed under different pH modifications. However, the mitovirus-infected isolates presented larger mycelial growth than the mitovirus-free ones when at the fungi’s optimal growing temperature of 15°C. When growing at certain osmotic potentials (–0.6 and –1.8 MPa) a reduction in growth of the mitovirus-infected isolates was observed. The results of this experiment suggest that mycelial growth among non-infected isolates and isolates naturally infected by mitovirus vary under different culture conditions, thus providing further insight into the effects of mitovirus on Gremmeniella abietina isolates.Los mitovirus son virus exclusivamente fúngicos que han sido aislados de algunos patógenos forestales (i.e. Cryphonectria parasitica, Gremmeniella abietina) y ya que pueden reducir la virulencia del hongo existe un creciente interés por su posible papel como agentes de control biológico. Se ha llevado a cabo un estudio para evaluar el efecto de la temperatura (5°C, 15°C, 25°C y 35°C), el pH (4, 5, 7 y 9) y el potencial osmótico (–0.6, –1.2, –1.8, –2.4 MPa) en el crecimiento micelial de siete aislados de G. abietina bajo condiciones controladas de laboratorio. Cuatro de los aislados albergaban mitovirus y tres de ellos no. Durante el experimento, el crecimiento micelial fue registrado semanalmente hasta completar 8 mediciones. Los aislados infectados con mitovirus presentaron mayor crecimiento micelial que los no infectados a la temperatura de crecimiento óptimo del hongo de 15°C. No se observaron efectos de la presencia de mitovirus entre los aislados infectados y los no infectados en los tratamientos de modificación del pH. Cuando se modificaron los potenciales osmóticos se observó una reducción del crecimiento micelial de los aislados infectados con mitovirus en los potenciales osmóticos de –0.6 y –1.8 MPa. Los resultados de este experimento sugieren que la presencia de los mitovirus afecta al crecimiento micelial del hongo bajo distintas condiciones de laboratorio. Este estudio proporciona un conocimiento más profundo de los efectos de las infecciones víricas en aislados españoles de Gremmeniella abietina

    Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency

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    We have determined the cross-section σ for color center generation under single Br ion impacts on amorphous SiO2. The evolution of the cross-sections, σ(E) and σ(Se), show an initial flat stage that we associate to atomic collision mechanisms. Above a certain threshold value (Se > 2 keV/nm), roughly coinciding with that reported for the onset of macroscopic disorder (compaction), σ shows a marked increase due to electronic processes. In this regime, a energetic cost of around 7.5 keV is necessary to create a non bridging oxygen hole center-E′ (NBOHC/E′) pair, whatever the input energy. The data appear consistent with a non-radiative decay of self-trapped excitons

    Unquenched flavor and tropical geometry in strongly coupled Chern-Simons-matter theories

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    We study various aspects of the matrix models calculating free energies and Wilson loop observables in supersymmetric Chern-Simons-matter theories on the three-sphere. We first develop techniques to extract strong coupling results directly from the spectral curve describing the large N master field. We show that the strong coupling limit of the gauge theory corresponds to the so-called tropical limit of the spectral curve. In this limit, the curve degenerates to a planar graph, and matrix model calculations reduce to elementary line integrals along the graph. As an important physical application of these tropical techniques, we study N=3 theories with fundamental matter, both in the quenched and in the unquenched regimes. We calculate the exact spectral curve in the Veneziano limit, and we evaluate the planar free energy and Wilson loop observables at strong coupling by using tropical geometry. The results are in agreement with the predictions of the AdS duals involving tri-Sasakian manifoldsComment: 32 pages, 7 figures. v2: small corrections, added an Appendix on the relation with the approach of 1011.5487. v3: further corrections and clarifications, final version to appear in JHE

    High-pressure study of the behavior of mineral barite by X-ray diffraction

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    In this paper, we report the angle-dispersive x-ray diffraction data of barite, BaSO 4, measured in a diamond-anvil cell up to a pressure of 48 GPa, using three different fluid pressure-transmitting media (methanol-ethanol mixture, silicone oil, and He). Our results show that BaSO 4 exhibits a phase transition at pressures that range from 15 to 27 GPa, depending on the pressure media used. This indicates that nonhydrostatic stresses have a crucial role in the high-pressure behavior of this compound. The new high-pressure (HP) phase has been solved and refined from powder data, having an orthorhombic P2 12 12 1 structure. The pressure dependence of the structural parameters of both room- and HP phases of BaSO 4 is also discussed in light of our theoretical first-principles total-energy calculations. Finally, a comparison between the different equations of state obtained in our experiments is reported. © 2011 American Physical Society.Financial support from the Spanish Consolider Ingenio 2010 Program (Project No. CDS2007-00045) is acknowledged. The work was also supported by Spanish MICCIN under Projects No. CTQ2009-14596-C02-01 and No. MAT2010-21270-C04-01 as well as from Comunidad de Madrid and European Social Fund: S2009/PPQ-1551 4161893 (QUIMAPRES). The ESRF is acknowledged for provision of beamtime.Santamaría-Pérez, D.; Gracia, L.; Garbarino, G.; Beltrán, A.; Chuliá-Jordán, R.; Gomis Hilario, O.; Errandonea, D.... (2011). High-pressure study of the behavior of mineral barite by X-ray diffraction. Physical Review B. 84:54102-1-54102-8. https://doi.org/10.1103/PhysRevB.84.054102S54102-154102-884RUBIN, A. E. (1997). Mineralogy of meteorite groups. Meteoritics & Planetary Science, 32(2), 231-247. doi:10.1111/j.1945-5100.1997.tb01262.xVegas, A. (2000). Cations in Inorganic Solids. 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Characterization of theTiSiO4structure and its pressure-induced phase transformations: Density functional theory study. Physical Review B, 80(9). doi:10.1103/physrevb.80.094105Blanco, M. A., Francisco, E., & Luaña, V. (2004). GIBBS: isothermal-isobaric thermodynamics of solids from energy curves using a quasi-harmonic Debye model. Computer Physics Communications, 158(1), 57-72. doi:10.1016/j.comphy.2003.12.001Errandonea, D., Santamaría-Perez, D., Vegas, A., Nuss, J., Jansen, M., Rodríguez-Hernandez, P., & Muñoz, A. (2008). Structural stability ofFe5Si3andNi2Sistudied by high-pressure x-ray diffraction andab initiototal-energy calculations. Physical Review B, 77(9). doi:10.1103/physrevb.77.094113Santamarı́a-Pérez, D., Nuss, J., Haines, J., Jansen, M., & Vegas, A. (2004). Iron silicides and their corresponding oxides: a high-pressure study of Fe5Si3. Solid State Sciences, 6(7), 673-678. doi:10.1016/j.solidstatesciences.2004.03.027Errandonea, D., Meng, Y., Somayazulu, M., & Häusermann, D. (2005). Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress. Physica B: Condensed Matter, 355(1-4), 116-125. doi:10.1016/j.physb.2004.10.030Klotz, S., Paumier, L., Le March, G., & Munsch, P. (2009). The effect of temperature on the hydrostatic limit of 4:1 methanol–ethanol under pressure. High Pressure Research, 29(4), 649-652. doi:10.1080/08957950903418194Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Lacomba-Perales, R., Errandonea, D., Meng, Y., & Bettinelli, M. (2010). High-pressure stability and compressibility ofAPO4(A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation. Physical Review B, 81(6). doi:10.1103/physrevb.81.064113Crichton, W. A., Parise, J. B., Antao, S. M., & Grzechnik, A. (2005). Evidence for monazite-, barite-, and AgMnO4(distorted barite)-type structures of CaSO4at high pressure and temperature. American Mineralogist, 90(1), 22-27. doi:10.2138/am.2005.1654Huang, T., Shieh, S. R., Akhmetov, A., Liu, X., Lin, C.-M., & Lee, J.-S. (2010). Pressure-induced phase transition inBaCrO4. Physical Review B, 81(21). doi:10.1103/physrevb.81.214117Zhang, F. X., Wang, J. W., Lang, M., Zhang, J. M., Ewing, R. C., & Boatner, L. A. (2009). High-pressure phase transitions ofScPO4andYPO4. Physical Review B, 80(18). doi:10.1103/physrevb.80.184114Panchal, V., Garg, N., & Sharma, S. M. (2006). Raman and x-ray diffraction investigations on BaMoO4under high pressures. Journal of Physics: Condensed Matter, 18(16), 3917-3929. doi:10.1088/0953-8984/18/16/00
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