Closed-form Jones matrix of dual-polarized inverted-vee dipole antennas over lossy ground

This paper presents a closed-form expression for the Jones matrix of a dual-polarized inverted-vee dipole antenna based on the Lorentz reciprocity theorem and the basic rules of electromagnetic refraction. The expression is used to determine the intrinsic cross-polarization ratio (IXR) as a function of droop angle, position of the source in the sky, antenna height, frequency, and reflection coefficient of the underlying ground. The expression is verified using full-wave simulations with a method-of-moments solver, showing very good agreement. It explains the increase in the IXR when the antenna is placed over a perfect electric ground plane. This result is used to explain the polarization properties of the Square Kilometre Array Log-periodic Antenna. Through the LOw-Frequency ARray Low-Band Antenna (LOFAR-LBA), the importance of the size of the ground plane is explained. Finally, design consideration for high polarization purity antennas is discussed

A New Family of Jumonji C Domain-Containing KDM Inhibitors Inspired by Natural Product Purpurogallin

Aberrant epigenetic modifications are involved in cancer development. Jumonji C domain-containing histone lysine demethylases (KDMs) are found mainly up-regulated in breast, prostate, and colon cancer. Currently, growing interest is focusing on the identification and development of new inhibitors able to block the activity of KDMs and thus reduce tumor progression. KDM4A is known to play a role in several cellular physiological processes, and was recently found overexpressed in a number of pathological states, including cancer. In this work, starting from the structure of purpurogallin 9aa, previously identified as a natural KDM4A inhibitor, we synthesized two main sets of compound derivatives in order to improve their inhibitory activity against KDM4A in vitro and in cells, as well as their antitumor action. Based on the hypothetical biogenesis of the 5-oxo-5H-benzo[7]annulene skeleton of the natural product purpurogallin (Salfeld, 1960; Horner et al., 1961; Dürckheimer and Paulus, 1985; Tanaka et al., 2002; Yanase et al., 2005) the pyrogallol and catechol units were first combined with structural modifications at different positions of the aryl ring using enzyme-mediated oxidative conditions, generating a series of benzotropolone analogs. Two of the synthetic analogs of purpurogallin, 9ac and 9bc, showed an efficient inhibition (50 and 80%) of KDM4A in enzymatic assays and in cells by increasing levels of its specific targets, H3K9me3/2 and H3K36me3. However, these two compounds/derivatives did not induce cell death. We then synthesized a further set of analogs of these two compounds with greater structural diversification. The most potent of these analogs, 9bf, displayed the highest KDM4A inhibitory enzymatic activity in vitro (IC50 of 10.1 and 24.37 μM) in colon cancer cells, and the strongest antitumor action in several solid and hematological human cancer cell lines with no toxic effect in normal cells. Our findings suggest that further development of this compound and its derivatives may lead to the identification of new therapeutic antitumor agents acting through inhibition of KDM4A

Development of a few TW Ti:Sa laser system at 100 Hz for proton acceleration

[EN] We report the development of a table-top high peak power Titanium:Sapphire (Ti:Sa) CPA laser working at 100 Hz capable of delivering 205 mJ, 55 fs pulses. Every amplification stage is pumped by Nd-doped solid-state lasers and fully powered by diodes. Thermal effects in the Ti:Sa amplifiers are compensated passively with optics. This system is intended to be used for proton acceleration experiments at high repetition rates.Centro para el Desarrollo Tecnológico Industrial (CDTI, Spain) within the INNPRONTA program, Grant no. IPT-20111027.Lera, R.; Bellido-Millán, PJ.; Sánchez, I.; Mur, P.; Seimetz, M.; Benlloch Baviera, JM.; Roso, L.... (2019). Development of a few TW Ti:Sa laser system at 100 Hz for proton acceleration. Applied Physics B. 125(1):1-8. https://doi.org/10.1007/s00340-018-7113-8S181251P. Zeitoun, G. Faivre, S. Sebban, T. Mocek, A. Hallou, M. Fajardo, D. Aubert, P. Balcou, F. Burgy, D. Douillet, S. Kazamias, G. de Lachèze-Murel, T. Lefrou, S. le Pape, P. Mercère, H. Merdji, A.S. Morlens, J.P. Rousseau, C. Valentin, Nature 431(7007), 426–429 (2004)V. Malka, S. Fritzler, E. Lefebvre, M.-M. Aleonard, F. Burgy, J.-P. Chambaret, J.-F. Chemin, K. Krushelnick, G. Malka, S.P.D. Mangles, Z. Najmudin, M. Pittman, J.-P. Rousseau, J.-N. Scheurer, B. Walton, A.E. Dangor, Science 298(5598), 1596–1600 (2002)H. Daido, M. Nishiuchi, A.S. Pirozhkov, Rep. Progress Phys. 75(5), 056401 (2012)A. Macchi, M. Borghesi, M. Passoni, Rev. Mod. Phys. 85, 751–793 (2013)T. Tajima, J.M. Dawson, Phys. Rev. Lett. 43, 267–270 (1979)M. Noaman-ul Haq, H. Ahmed, T. Sokollik, L. Yu, Z. Liu, X. Yuan, F. Yuan, M. Mirzaie, X. Ge, L. Chen, J. Zhang, Phys. Rev. Accel. Beams 20, 041301 (2017)D. Strickland, G. Mourou, Opt. Commun. 53(3), 219–221 (1985)G. Cheriaux, B. Walker, L.F. Dimauro, P. Rousseau, F. Salin, J.P. Chambaret, Opt. Lett. 21(6), 414–416 (1996)P. Tournois, Opt. Commun. 140(4), 245–249 (1997)R. Soulard, A. Brignon, S. Raby, E. Durand, R. Moncorgé, Appl. Phys. B 106(2), 295–300 (2012)J. Liu, L. Ge, L. Feng, H. Jiang, H. Su, T. Zhou, J. Wang, Q. Gao, J. Li, Chin. Opt. Lett. 14(5), 051404 (2016)A. Maleki, M.K. Tehrani, H. Saghafifar, M.H.M. Dindarlu, H. Ebadian, Laser Phys. 26(2), 025003 (2016)R. Lera, F. Valle-Brozas, S. Torres-Peiró, A.R. de-la Cruz, M. Galán, P. Bellido, M. Seimetz, J.M. Benlloch, L. Roso, Appl. Opt. 55(33), 9573–9576 (2016)R. Lausten, P. Balling, J. Opt. Soc. Am. B 20(7), 1479–1485 (2003)I. Nam, M. Kim, T.H. Lee, S.W. Lee, H. Suk, Curr. Appl. Phys. 15(4), 468–472 (2015)E. Treacy, IEEE J. Quantum Electron. 5(9), 454–458 (1969)A. Trisorio, S. Grabielle, M. Divall, N. Forget, C.P. Hauri, Opt. Lett. 37(14), 2892–2894 (2012)Y.-H. Cha, Y.-W. Lee, S.M. Nam, J.M. Han, Y.J. Rhee, B.D. Yoo, B.C. Lee, Y.U. Jeong, Appl. Opt. 46(28), 6854–6858 (2007)P. Bellido, R. Lera, M. Seimetz, A.R. de la Cruz, S. Torres-Peiró, M. Galán, P. Mur, I. Sánchez, R. Zaffino, L. Vidal, A. Soriano, S. Sánchez, F. Sánchez, M. Rodríguez-Álvarez, J. Rigla, L. Moliner, A. Iborra, L. Hernández, D. Grau-Ruiz, A. González, J. García-Garrigos, E. Díaz-Caballero, P. Conde, A. Aguilar, L. Roso, J. Benlloch, J. Instrum. 12(05), T05001 (2017

The Hydrogen Epoch of Reionization Array Dish II: Characterization of Spectral Structure with Electromagnetic Simulations and its science Implications

We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish's design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA's suspended feed and its parabolic dish reflector that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA's ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effective for increasing the sensitivity of EoR experiments at relatively low cost. We find that electromagnetic resonances in the HERA feed's cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays ($-40$ dB at 200 ns) which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below $k_\parallel \lesssim 0.2$ $h$Mpc$^{-1}$, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.Comment: Accepted to ApJ, 18 pages, 17 Figures. Replacement matches accepted manuscrip

Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector

CR-39 nuclear track material is frequently used for the detection of protons accelerated in laser-plasma interactions. The measurement of track densities allows for determination of particle angular distributions, and information on the kinetic energy can be obtained by the use of passive absorbers. We present a precise method of measuring spectral distributions of laser-accelerated protons in a single etching and analysis process. We make use of a one-to-one relation between proton energy and track size and present a precise calibration based on monoenergetic particle beams. While this relation is limited to proton energies below 1 MeV, we show that the range of spectral measurements can be significantly extended by simultaneous use of absorbers of suitable thicknesses. Examples from laser-plasma interactions are presented, and quantitative results on proton energies and particle numbers are compared to those obtained from a time-of-flight detector. The spectrum end points of continuous energy distributions have been determined with both detector types and coincide within 50-100 keV

Wafer-scale fabrication of target arrays for stable generation of proton beams by laser-plasma interaction

[EN] Large-scale fabrication of targets for laser-driven acceleration of ion beams is a prerequisite to establish suitable applications, and to keep up with the challenge of increasing repetition rate of currently available high-power lasers. Here we present manufacturing and test results of large arrays of solid targets for TNSA laser-driven ion acceleration. By applying micro-electro-mechanical-system (MEMS) based methods allowing for parallel processing of thousands of targets on a single Si wafer, sub-micrometric, thin-layer metallic membranes were fabricated by combining photolithography, physical and chemical vapor deposition, selective etching, and Si micromachining. These structures were characterized by using optical and atomic force microscopy. Their performance for the production of laser-driven proton beams was tested on a purpose-made table-top Ti:Sapphire laser system running at 3 TW peak power with a contrast over ASE of 108. We have performed several test series achieving maximum proton energy values around 2 MeV.This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MEINCOM. This project has been financed by the Spanish Ministry for Economy and Competitiveness within the Retos- Colaboración 2015 initiative, ref. RTC-2015-3278-1. P. Mur has received a grant of the Garantía Juvenil 2015 program.Zaffino, R.; Seimetz, M.; Ruiz-De La Cruz, A.; Sánchez, I.; Mur, P.; Bellido-Millán, PJ.; Lera, R.... (2018). Wafer-scale fabrication of target arrays for stable generation of proton beams by laser-plasma interaction. Journal of Physics: Conference Series (Online). 1079. https://doi.org/10.1088/1742-6596/1079/1/012007S0120071079Abedi, S., Dorranian, D., Abari, M. E., & Shokri, B. (2011). Relativistic effects in the interaction of high intensity ultra-short laser pulse with collisional underdense plasma. Physics of Plasmas, 18(9), 093108. doi:10.1063/1.3633529Antici, P., Fuchs, J., d’ Humières, E., Lefebvre, E., Borghesi, M., Brambrink, E., … Pépin, H. (2007). Energetic protons generated by ultrahigh contrast laser pulses interacting with ultrathin targets. Physics of Plasmas, 14(3), 030701. doi:10.1063/1.2480610Ceccotti, T., Lévy, A., Popescu, H., Réau, F., D’Oliveira, P., Monot, P., … Martin, P. (2007). Proton Acceleration with High-Intensity Ultrahigh-Contrast Laser Pulses. Physical Review Letters, 99(18). doi:10.1103/physrevlett.99.18500

Efficient proton acceleration from a 3 TW table-top laser interacting with submicrometric mass-produced solid targets

[EN] Thin layer membranes with controllable features and material arrangements are often used as target materials for laser driven particle accelerators. Reduced cost, large scale fabrication of such membranes with high reproducibility, and good stability are central for the efficient production of proton beams. These characteristics are of growing importance in the context of advanced laser light sources where increased repetition rates boost the need for consumable targets with design and properties adjusted to study the different phenomena arising in ultra-intense laser-plasma interaction. Wepresent the fabrication of sub-micrometric thin-layer gold or aluminum membranes in a silicon wafer frame by using nano/micro-electro-mechanical-system (N/MEMS) processing which are suitable for rapid patterning and machining of many samples at the same time and allowing for high-throughput production of targets for laser-driven acceleration. Obtained targets were tested for laserproton acceleration through the Target Normal Sheath Acceleration mechanism (TNSA) in a series of experiments carried out on a purpose-made table-top Ti:Sa running at 3 TW peak power and 10 Hz diode pump rate with a contrast over ASE of 10(8)The authors highly appreciate the collaboration of Radosys (Budapest) which provided CR-39 detector material, etching bath, and readout equipment. This project has been financed by the Spanish Ministry for Economy and Competitiveness within the Retos-Colaboracion 2015 initiative, ref. RTC-2015-3278-1. P Mur has received a grant of the Garantia Juvenil 2015 program. This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MEINCOM.Zaffino, R.; Seimetz, M.; Ruiz-De La Cruz, A.; Sánchez, I.; Mur, P.; Quirión, D.; Bellido-Millán, PJ.... (2018). Efficient proton acceleration from a 3 TW table-top laser interacting with submicrometric mass-produced solid targets. Journal of Physics Communications. 2(4):1-6. https://doi.org/10.1088/2399-6528/aabc25S1624Borghesi, M., Campbell, D. H., Schiavi, A., Haines, M. G., Willi, O., MacKinnon, A. J., … Bulanov, S. (2002). Electric field detection in laser-plasma interaction experiments via the proton imaging technique. Physics of Plasmas, 9(5), 2214-2220. doi:10.1063/1.1459457Ledingham, K., Bolton, P., Shikazono, N., & Ma, C.-M. (2014). Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress. Applied Sciences, 4(3), 402-443. doi:10.3390/app4030402Spindloe, C., Arthur, G., Hall, F., Tomlinson, S., Potter, R., Kar, S., … Tolley, M. K. (2016). High volume fabrication of laser targets using MEMS techniques. Journal of Physics: Conference Series, 713, 012002. doi:10.1088/1742-6596/713/1/012002Schomburg, W. K. (2011). Thin Films. RWTHedition, 9-20. doi:10.1007/978-3-642-19489-4_4Bellido, P., Lera, R., Seimetz, M., Cruz, A. R. la, Torres-Peirò, S., Galán, M., … Benlloch, J. M. (2017). Characterization of protons accelerated from a 3 TW table-top laser system. Journal of Instrumentation, 12(05), T05001-T05001. doi:10.1088/1748-0221/12/05/t05001Mayer, M. (1999). SIMNRA, a simulation program for the analysis of NRA, RBS and ERDA. AIP Conference Proceedings. doi:10.1063/1.59188Ceccotti, T., Lévy, A., Popescu, H., Réau, F., D’Oliveira, P., Monot, P., … Martin, P. (2007). Proton Acceleration with High-Intensity Ultrahigh-Contrast Laser Pulses. Physical Review Letters, 99(18). doi:10.1103/physrevlett.99.185002Dollar, F., Reed, S. A., Matsuoka, T., Bulanov, S. S., Chvykov, V., Kalintchenko, G., … Maksimchuk, A. (2013). High-intensity laser-driven proton acceleration enhancement from hydrogen containing ultrathin targets. Applied Physics Letters, 103(14), 141117. doi:10.1063/1.4824361Neely, D., Foster, P., Robinson, A., Lindau, F., Lundh, O., Persson, A., … McKenna, P. (2006). Enhanced proton beams from ultrathin targets driven by high contrast laser pulses. Applied Physics Letters, 89(2), 021502. doi:10.1063/1.2220011Green, J. S., Carroll, D. C., Brenner, C., Dromey, B., Foster, P. S., Kar, S., … Zepf, M. (2010). Enhanced proton flux in the MeV range by defocused laser irradiation. New Journal of Physics, 12(8), 085012. doi:10.1088/1367-2630/12/8/085012Giuffrida, L., Svensson, K., Psikal, J., Dalui, M., Ekerfelt, H., Gallardo Gonzalez, I., … Margarone, D. (2017). Manipulation of laser-accelerated proton beam profiles by nanostructured and microstructured targets. Physical Review Accelerators and Beams, 20(8). doi:10.1103/physrevaccelbeams.20.08130

PLoS Genet

The retinoid X receptors (RXRs) are ligand-activated transcription factors which heterodimerize with a number of nuclear hormone receptors, thereby controlling a variety of (patho)-physiological processes. Although synthetic RXR ligands are developed for the treatment of various diseases, endogenous ligand(s) for these receptors have not been conclusively identified. We show here that mice lacking cellular retinol binding protein (Rbp1-/-) display memory deficits reflecting compromised RXR signaling. Using HPLC-MS and chemical synthesis we identified in Rbp1-/- mice reduced levels of 9-cis-13,14-dihydroretinoic acid (9CDHRA), which acts as an RXR ligand since it binds and transactivates RXR in various assays. 9CDHRA rescues the Rbp1-/- phenotype similarly to a synthetic RXR ligand and displays similar transcriptional activity in cultured human dendritic cells. High endogenous levels of 9CDHRA in mice indicate physiological relevance of these data and that 9CDHRA acts as an endogenous RXR ligand

Metaphors We Think With: The Role of Metaphor in Reasoning

The way we talk about complex and abstract ideas is suffused with metaphor. In five experiments, we explore how these metaphors influence the way that we reason about complex issues and forage for further information about them. We find that even the subtlest instantiation of a metaphor (via a single word) can have a powerful influence over how people attempt to solve social problems like crime and how they gather information to make “well-informed” decisions. Interestingly, we find that the influence of the metaphorical framing effect is covert: people do not recognize metaphors as influential in their decisions; instead they point to more “substantive” (often numerical) information as the motivation for their problem-solving decision. Metaphors in language appear to instantiate frame-consistent knowledge structures and invite structurally consistent inferences. Far from being mere rhetorical flourishes, metaphors have profound influences on how we conceptualize and act with respect to important societal issues. We find that exposure to even a single metaphor can induce substantial differences in opinion about how to solve social problems: differences that are larger, for example, than pre-existing differences in opinion between Democrats and Republicans