Optimal streaks in a Falkner-Skan boundary layer

This paper deals with the optimal streaky perturbations (which maximize the perturbed energy growth) in a wedge flow boundary layer. These three dimensional perturbations are governed by a system of linearized boundary layer equations around the Falkner-Skan base flow. Based on an asymptotic analysis of this system near the free stream and the leading edge singularity, we show that for acute wedge semi-angle, all solutions converge after a streamwise transient to a single streamwise-growing solution of the linearized equations, whose initial condition near the leading edge is given by an eigenvalue problem first formulated in this context by Tumin (2001). Such a solution may be regarded as a streamwise evolving most unstable streaky mode, in analogy with the usual eigenmodes in strictly parallel flows, and shows an approximate self-similarity, which was partially known and is completed in this paper. An important consequence of this result is that the optimization procedure based on the adjoint equations heretofore used to define optimal streaks is not necessary. Instead, a simple low-dimensional optimization process is proposed and used to obtain optimal streaks. Comparison with previous results by Tumin and Ashpis (2003) shows an excellent agreement. The unstable streaky mode exhibits transient growth if the wedge semi-angle is smaller than a critical value that is slightly larger than $\pi/6$, and decays otherwise. Thus the cases of right and obtuse wedge semi-angles exhibit less practical interest, but they show a qualitatively different behavior, which is briefly described to complete the analysis

Different coordination modes of an aryl-substituted hydrotris(pyrazolyl) borate ligand in rhodium and iridium complexes

Complexes TptolRh(C2H4)2 (1a) and TptolRh(CH2C(Me)C(Me)CH2) (1b) have been prepared by reaction of KTptol with the appropriate [RhCl(olefin)2]2 dimer (Tptol means hydrotris(3-p-tolylpyrazol-1-yl)borate). The two complexes show a dynamic behaviour that involves exchange between κ2 and κ3 coordination modes of the Tptol ligand. The iridium analogue, TptolIr(CH2C(Me)CHCH2) (2) has also been synthesized, and has been converted into the Ir(III) dinitrogen complex [(κ4-N,N',N'',C-Tptol)Ir(Ph)(N2) (3) by irradiation with UV light under a dinitrogen atmosphere. Compound 3 constitutes a rare example of Ir(III)-N2 complex structurally characterized by X-ray crystallography. Its N2 ligand can be easily substituted by acetonitrile or ethylene upon heating and denticity changes in the Tptol ligand, from κ4-N,N',N'',C (monometallated Tptol, from now on represented as Tptol′) to κ5-N,N′,N″,C,C″ (dimetallated Tp tol ligand, represented as Tptol″) have been observed. When complex 3 is heated in the presence of acetylene, dimerization of the alkyne takes place to yield the enyne complex [(κ5-N,N′,N′′,C,C′-Tp tol)Ir(CH2CHCCH), 7̧ in which the unsaturated organic moiety is bonded to iridium through the carbon-carbon double bond.Ministerio de Educación y Ciencia CTQ2007-62814Consolider-Ingenio 2010 CSD2007-00006Junta de Andalucía FQM-3151, FQM-672CONACYT 22934

Zinc: What Is Its Role in Lung Cancer?

Recently, zinc emerged as an important signaling molecule, activating intracellular pathways and regulating cell fate, although our knowledge remains incomplete. Zinc is required in many enzymatic and metabolic pathways, playing roles as enzyme cofactors. In normal cell physiology, optimal zinc availability is essential for regular growth and proliferation. Zinc accumulation has varied effects: from stimulation to inhibition of cell growth, depending on type. There is evidence that zinc is capable of inducing apoptosis in some cancers, while others proved that zinc may act as apoptosis activator depending on the dose and cell type. Upregulation of telomerase in most cancer tissues is considered to be responsible for unlimited proliferation of cancer cells, and in some cell lines, it was induced by Zn. These suggest that Zn is highly involved in cell cycle and metabolism; whether it goes to the survival or the cancer pathway depends on the concentration and the cell type involved. Nevertheless, the conclusion is that Zn is not just another trace element; but a vital one and further studies are needed to elucidate the mechanisms involved in cancer and metastatic spread in order to identify potential therapies

Simulation Study for Designing a Dedicated Cardiac TOF-PET System

[EN] The development of dedicated positron emission tomography scanners is an active area of research, especially aiming at the improvement of lesion detection and in support of cancer treatment and management. Recently, dedicated Positron Emission Tomography (PET) systems with different configurations for specific organs have been developed for improving detection effectiveness. Open geometries are always subject to distortion and artifacts in the reconstructed images. Therefore, the aim of this work is to determine the optimal geometry for a novel cardiac PET system that will be developed by our team, and determine the time resolution needed to achieve reasonable image quality for the chosen geometry. The proposed geometries consist of 36 modules. These modules are arranged in two sets of two plates, each one with different configurations. We performed Monte Carlo simulations with different TOF resolutions, in order to test the image quality improvement in each case. Our results show, as expected, that increasing TOF resolution reduces distortion and artifact effects. We can conclude that a TOF resolution of the order of 200 ps is needed to reduce the artifacts, to acceptable levels, generated in the simulated cardiac-PET open geometries.This project has been co-financed by the Spanish Government Grants TEC2016-79884-C2 and RTC-2016-5186-1, by the European Union through the European Regional Development Fund (ERDF) and by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 695536). The work of V.I. was supported by the Generalitat Valenciana APOSTD/2019/086 fellowship.Oliver-Gil, S.; Moliner, L.; Ilisie, V.; Benlloch Baviera, JM.; Rodríguez-Álvarez, M. (2020). Simulation Study for Designing a Dedicated Cardiac TOF-PET System. Sensors. 20(5):1-16. https://doi.org/10.3390/s20051311S116205Gaemperli, O., & Kaufmann, P. A. (2011). PET and PET/CT in cardiovascular disease. Annals of the New York Academy of Sciences, 1228(1), 109-136. doi:10.1111/j.1749-6632.2011.06030.xThackeray, J. T., & Bengel, F. M. (2018). Molecular Imaging of Myocardial Inflammation With Positron Emission Tomography Post-Ischemia. JACC: Cardiovascular Imaging, 11(9), 1340-1355. doi:10.1016/j.jcmg.2018.05.026Li, Z., Gupte, A. A., Zhang, A., & Hamilton, D. J. (2017). Pet Imaging and its Application in Cardiovascular Diseases. Methodist DeBakey Cardiovascular Journal, 13(1), 29. doi:10.14797/mdcj-13-1-29Juárez-Orozco, L. E., Tio, R. A., Alexanderson, E., Dweck, M., Vliegenthart, R., El Moumni, M., … Slart, R. H. J. A. (2017). Quantitative myocardial perfusion evaluation with positron emission tomography and the risk of cardiovascular events in patients with coronary artery disease: a systematic review of prognostic studies. European Heart Journal - Cardiovascular Imaging, 19(10), 1179-1187. doi:10.1093/ehjci/jex331Schelbert, H. R. (2009). Quantification of Myocardial Blood Flow: What is the Clinical Role? Cardiology Clinics, 27(2), 277-289. doi:10.1016/j.ccl.2008.12.009Knuuti, J., Kajander, S., Mäki, M., & Ukkonen, H. (2009). Quantification of myocardial blood flow will reform the detection of CAD. Journal of Nuclear Cardiology, 16(4), 497-506. doi:10.1007/s12350-009-9101-1Peng, H. (2015). Design study of a cardiac-dedicated PET system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 779, 39-46. doi:10.1016/j.nima.2015.01.042Gonzalez, A. J., Sanchez, F., & Benlloch, J. M. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences, 2(5), 388-403. doi:10.1109/trpms.2018.2846745Moliner, L., Rodríguez-Alvarez, M. J., Catret, J. V., González, A., Ilisie, V., & Benlloch, J. M. (2019). NEMA Performance Evaluation of CareMiBrain dedicated brain PET and Comparison with the whole-body and dedicated brain PET systems. Scientific Reports, 9(1). doi:10.1038/s41598-019-51898-zAhmed, A. M., Tashima, H., Yoshida, E., Nishikido, F., & Yamaya, T. (2017). Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors. Physics in Medicine and Biology, 62(11), 4541-4550. doi:10.1088/1361-6560/aa685cCho, Z.-H., Son, Y.-D., Kim, H.-K., Kwon, D.-H., Joo, Y.-H., Ra, J. B., … Kim, Y.-B. (2019). Development of Positron Emission Tomography With Wobbling and Zooming for High Sensitivity and High-Resolution Molecular Imaging. IEEE Transactions on Medical Imaging, 38(12), 2875-2882. doi:10.1109/tmi.2019.2916326Surti, S., & Karp, J. S. (2008). Design considerations for a limited angle, dedicated breast, TOF PET scanner. Physics in Medicine and Biology, 53(11), 2911-2921. doi:10.1088/0031-9155/53/11/010Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Grant, A. M., Deller, T. W., Khalighi, M. M., Maramraju, S. H., Delso, G., & Levin, C. S. (2016). NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system. Medical Physics, 43(5), 2334-2343. doi:10.1118/1.4945416Van Sluis, J., de Jong, J., Schaar, J., Noordzij, W., van Snick, P., Dierckx, R., … Boellaard, R. (2019). Performance Characteristics of the Digital Biograph Vision PET/CT System. Journal of Nuclear Medicine, 60(7), 1031-1036. doi:10.2967/jnumed.118.215418Ito, M., Lee, M. S., & Lee, J. S. (2013). Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout. Physics in Medicine and Biology, 58(5), 1269-1282. doi:10.1088/0031-9155/58/5/1269Bugalho, R., Di Francesco, A., Ferramacho, L., Leong, C., Niknejad, T., Oliveira, L., … Varela, J. (2018). Experimental results with TOFPET2 ASIC for time-of-flight applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 195-198. doi:10.1016/j.nima.2017.11.034Gundacker, S., Auffray, E., Frisch, B., Jarron, P., Knapitsch, A., Meyer, T., … Lecoq, P. (2013). Time of flight positron emission tomography towards 100ps resolution with L(Y)SO: an experimental and theoretical analysis. Journal of Instrumentation, 8(07), P07014-P07014. doi:10.1088/1748-0221/8/07/p07014A Code System for Monte Carlo Simulation of Electron and Photon Transporthttp://www.oecd-nea.org/lists/penelope.htmlStrydhorst, J., & Buvat, I. (2016). Redesign of the GATE PET coincidence sorter. Physics in Medicine and Biology, 61(18), N522-N531. doi:10.1088/0031-9155/61/18/n522Baró, J., Sempau, J., Fernández-Varea, J. M., & Salvat, F. (1995). PENELOPE: An algorithm for Monte Carlo simulation of the penetration and energy loss of electrons and positrons in matter. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 100(1), 31-46. doi:10.1016/0168-583x(95)00349-5Sempau, J., Acosta, E., Baro, J., Fernández-Varea, J. M., & Salvat, F. (1997). An algorithm for Monte Carlo simulation of coupled electron-photon transport. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 132(3), 377-390. doi:10.1016/s0168-583x(97)00414-xSempau, J., Fernández-Varea, J. M., Acosta, E., & Salvat, F. (2003). Experimental benchmarks of the Monte Carlo code penelope. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 207(2), 107-123. doi:10.1016/s0168-583x(03)00453-1Reader, A. J., Ally, S., Bakatselos, F., Manavaki, R., Walledge, R. J., Jeavons, A. P., … Zweit, J. (2002). One-pass list-mode EM algorithm for high-resolution 3-D PET image reconstruction into large arrays. IEEE Transactions on Nuclear Science, 49(3), 693-699. doi:10.1109/tns.2002.1039550Spanoudaki, V. C., & Levin, C. S. (2010). Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET). Sensors, 10(11), 10484-10505. doi:10.3390/s101110484Siddon, R. L. (1985). Fast calculation of the exact radiological path for a three-dimensional CT array. Medical Physics, 12(2), 252-255. doi:10.1118/1.595715Vandenberghe, S., Daube-Witherspoon, M. E., Lewitt, R. M., & Karp, J. S. (2006). Fast reconstruction of 3D time-of-flight PET data by axial rebinning and transverse mashing. Physics in Medicine and Biology, 51(6), 1603-1621. doi:10.1088/0031-9155/51/6/017Performance Measurements of Positron Emission Tomographshttps://www.nema.org/Standards/ComplimentaryDocuments/Contents%20and%20Scope%20NEMA%20NU%202%202012.pdfYu, W., & Zeng, L. (2014). A Novel Weighted Total Difference Based Image Reconstruction Algorithm for Few-View Computed Tomography. PLoS ONE, 9(10), e109345. doi:10.1371/journal.pone.0109345Tashima, H., Yamaya, T., Yoshida, E., Kinouchi, S., Watanabe, M., & Tanaka, E. (2012). A single-ring OpenPET enabling PET imaging during radiotherapy. Physics in Medicine and Biology, 57(14), 4705-4718. doi:10.1088/0031-9155/57/14/4705Yamaya, T., Inaniwa, T., Minohara, S., Yoshida, E., Inadama, N., Nishikido, F., … Murayama, H. (2008). A proposal of an open PET geometry. Physics in Medicine and Biology, 53(3), 757-773. doi:10.1088/0031-9155/53/3/015Miyake, K. K., Matsumoto, K., Inoue, M., Nakamoto, Y., Kanao, S., Oishi, T., … Togashi, K. (2014). Performance Evaluation of a New Dedicated Breast PET Scanner Using NEMA NU4-2008 Standards. Journal of Nuclear Medicine, 55(7), 1198-1203. doi:10.2967/jnumed.113.131565Yamamoto, S., Honda, M., Oohashi, T., Shimizu, K., & Senda, M. (2011). Development of a Brain PET System, PET-Hat: A Wearable PET System for Brain Research. IEEE Transactions on Nuclear Science, 58(3), 668-673. doi:10.1109/tns.2011.2105502Garibaldi, F., Capuani, S., Colilli, S., Cosentino, L., Cusanno, F., Leo, R. D., … Tamma, C. (2013). TOPEM: A PET-TOF endorectal probe, compatible with MRI for diagnosis and follow up of prostate cancer. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 702, 13-15. doi:10.1016/j.nima.2012.09.020González-Montoro, A., Sánchez, F., Martí, R., Hernández, L., Aguilar, A., Barberá, J., … González, A. J. (2018). Detector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 372-377. doi:10.1016/j.nima.2017.10.09

Transverse rectification in superconducting thin films with arrays of asymmetric defects

Superconducting Nb films have been grown on top of arrays of Cu nanotriangles. These asymmetric pinning centers strongly modify the vortex lattice dynamics. Two rectification effects have been observed: (i) longitudinal ratchet effect when the input currents are injected perpendicular to the triangle reflection symmetry axis and (ii) transverse rectification effect hen the input currents are injected parallel to the triangle reflection symmetry axis and the output voltage drop occurs perpendicular to the triangle reflection symmetry axis. Increasing the applied magnetic field, the former shows a change of the output voltage polarity, the transverse output voltage does not show any polarity reversal

Removal of Phenolic Compounds from Water Using Copper Ferrite Nanosphere Composites as Fenton Catalysts

The authors affiliated to the University of Jaén (Department of Inorganic and Organic Chemistry) acknowledge financial support from the Spanish Ministry of Economy, Industry and Competitiveness and from FEDER (Project CTQ2016-80978-C2-1-R). L. Mateus thanks the Asociación Universitaria Iberoamericana de Postgrado (AUIP) and University of Jaén for their grant and financial support.Copper ferrites containing Cu+ ions can be highly active heterogeneous Fenton catalysts due to synergic effects between Fe and Cu ions. Therefore, a method of copper ferrite nanosphere (CFNS) synthesis was selected that also permits the formation of cuprite, obtaining a CFNS composite that was subsequently calcined up to 400 °C. Composites were tested as Fenton catalysts in the mineralization of phenol (PHE), p-nitrophenol (PNP) and p-aminophenol (PAP). Catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and magnetic measurements. Degradation of all phenols was practically complete at 95% total organic carbon (TOC) removal. Catalytic activity increased in the order PHE < PNP < PAP and decreased when the calcination temperature was raised; this order depended on the electronic effects of the substituents of phenols. The as-prepared CFNS showed the highest catalytic activity due to the presence of cubic copper ferrite and cuprite. The Cu+ surface concentration decreased after calcination at 200 °C, diminishing the catalytic activity. Cuprite alone showed a lower activity than the CFNS composite and the homogeneous Fenton reaction had almost no influence on its overall activity. CFNS activity decreased with its reutilization due to the disappearance of the cuprite phase. Degradation pathways are proposed for the phenols.This research was funded by Spanish Ministry of Economy, Industry and Competitiveness and FEDER (grant number CTQ2016-80978-C2-1-R), Asociación Universitaria Iberoamericana de Postgrado (AUIP) and University of Jaén

Respuesta reproductiva de conejas alimentadas con dietas enriquecidas con aceite de salmón

Un total de 136 conejas luníparasse alimentaron ad libitum desde las 10 semanas de edad con dos piensos isofibrosos, isoenergéticos e isoproteicos formulados con dos fuentes de grasa diferentes: manteca (grupo C; n=68) y un suplemento a base de aceite de salmón rico en ácidos grasos poliinsaturados (PUFA) n=3 (grupo P, n=68) con un nivel de inclusión de 1,5% (7,5g/kg) hasta el primer parto y de 3% (15g/kg) hasta el 2º destete. El peso y la composición corporal de las conejas a lo largo del estudio fueron similares entre grupos a pesar de que las conejas del grupo P redujeron el consumo al incrementar el nivel de inclusión de PUFA n-3. La prolificidad, el peso de los gazapos al nacimiento y el número de destetados fue similar en los dos grupos pero en los gazapos del grupo C la ganancia media diaria tendió a ser mayo, así como su peso al destete. No obstante, la fertilidad media fue más de un 12% superior en las conejas del grupo P, por lo que, el número estimado de gazapos destetados por coneja y año resultó mayor en ellas. En conclusión, el incremento en los niveles de inclusión de ácidos grasos poliisaturados n-3 de 7,5 a 15 g/kg después del primer parto disminuyó el consumo de las madres reduciendo el crecimiento de sus camadas pero incidiendo positivamente sobre su fertilidad

Using Markov-Switching models in US stocks optimal portfolio selection in a Black–Litterman context (Part 1)

In this study, we tested the benefit of using Markov-Switching (M-S) models to forecast the views of the 26 most traded stocks in the US in a Black–Litterman (B–L) optimal selection context. With weekly historical data of these stocks from 1 January 1980, we estimated and simulated (from 7 January 2000, to 7 February 2022) three portfolios that used M-S views in each stock and blended them with the market equilibrium views in a B–L context. Our position was that the B–L optimal portfolios could generate alpha (extra return) against a buy-and-hold and an actively managed portfolio with sample portfolio parameters (à la Markowitz, SampP). Our results suggest that the outperformance of the B–L managed portfolios holds only in the short term. In the long-term, the performance of the B–L portfolios, the SampP, and the market portfolio are statistically equal in terms of returns or their mean–variance efficiency in an ex-ante or ex-post analysis.Junta de Extremadur

Escape dynamics in the discrete repulsive φ4 model

We study deterministic escape dynamics of the discrete Klein-Gordon model with a repulsive quartic on-site potential. Using a combination of analytical techniques, based on differential and algebraic inequalities and selected numerical illustrations, we first derive conditions for collapse of an initially excited single-site unit, for both the Hamiltonian and the linearly damped versions of the system and showcase different potential fates of the single-site excitation, such as the possibility to be "pulled back" from outside the well or to "drive over" the barrier some of its neighbors. Next, we study the evolution of a uniform (small) segment of the chain and, in turn, consider the conditions that support its escape and collapse of the chain. Finally, our path from one to the few and finally to the many excited sites is completed by a modulational stability analysis and the exploration of its connection to the escape process for plane wave initial data. This reveals the existence of three distinct regimes, namely modulational stability, modulational instability without escape and, finally, modulational instability accompanied by escape. These are corroborated by direct numerical simulations. In each of the above cases, the variations of the relevant model parameters enable a consideration of the interplay of discreteness and nonlinearity within the observed phenomenology. © 2012 Elsevier B.V. All rights reserved