Epidemiological and evolutionary consequences of life-history trade-offs in pathogens

Peer reviewe

Extreme & High Synchrotron Peaked Blazars at the limit of Fermi-LAT detectability: the γ\gamma-ray spectrum of 1BIGB sources

We present the 1-100 GeV spectral energy distribution for a population of 148 high-synchrotron-peaked blazars (HSPs) recently detected with Fermi-LAT as part of the First Brazil-ICRANet Gamma-ray Blazar catalogue (1BIGB). Most of the 1BIGB sources do not appear in previous Fermi-LAT catalogues and their gamma-ray spectral properties are presented here for the first time, representing a significant new extension of the gamma-ray blazar population. Since our sample was originally selected from an excess signal in the 0.3-500 GeV band, the sources stand out as promising TeV blazar candidates, potentially in reach of the forthcoming very-high-energy (VHE) gamma-ray observatory, CTA. The flux estimates presented here are derived considering PASS8 data, integrating over more than 9 years of Fermi-LAT observations. We also review the full broadband fit between 0.3-500 GeV presented in the original 1BIGB paper for all sources, updating the power-law parameters with currently available Fermi-LAT dataset. The importance of these sources in the context of VHE population studies with both current instruments and the future CTA is evaluated. To do so, we select a subsample of 1BIGB sources and extrapolate their gamma-ray SEDs to the highest energies, properly accounting for absorption due to the extragalactic background light. We compare those extrapolations to the published CTA sensitivity curves and estimate their detectability by CTA. Two notable sources from our sample, namely 1BIGB J224910.6-130002 and 1BIGB J194356.2+211821, are discussed in greater detail. All gamma-ray SEDs, which are shown here for the first time, are made publicly available via the Brazilian Science Data Center (BSDC) service, maintained at CBPF, in Rio de Janeiro.Comment: 13 pages, 6 figure

GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers

The LIGO-Virgo Collaboration has announced the detection of GW170817 and has associated it with GRB 170817A. These signals have been followed after 11 hours by the optical and infrared emission of AT 2017gfo. The origin of this complex phenomenon has been attributed to a neutron star-neutron star (NS-NS) merger. In order to probe this association we confront our current understanding of the gravitational waves and associated electromagnetic radiation with four observed GRBs originating in binaries composed of different combinations NSs and white dwarfs (WDs). We consider 1) GRB 090510 the prototype of NS-NS merger leading to a black hole (BH); 2) GRB 130603B the prototype of a NS-NS merger leading to massive NS (MNS) with an associated kilonova; 3) GRB 060614 the prototype of a NS-WD merger leading to a MNS with an associated kilonova candidate; 4) GRB 170817A the prototype of a WD-WD merger leading to massive WD with an associated AT 2017gfo-like emission. None of these systems support the above mentioned association. The clear association between GRB 170817A and AT 2017gfo has led to introduce a new model based on on a new subfamily of GRBs originating from WD-WD mergers. We show how this novel model is in agreement with the exceptional observations in the optical, infrared, X- and gamma-rays of GRB 170817A-AT 2017gfo.Comment: version accepted for publication in JCAP. Missing references adde

LATTES: a novel detector concept for a gamma-ray experiment in the Southern hemisphere

The Large Array Telescope for Tracking Energetic Sources (LATTES), is a novel concept for an array of hybrid EAS array detectors, composed of a Resistive Plate Counter array coupled to a Water Cherenkov Detector, planned to cover gamma rays from less than 100 GeV up to 100 TeVs. This experiment, to be installed at high altitude in South America, could cover the existing gap in sensitivity between satellite and ground arrays. The low energy threshold, large duty cycle and wide field of view of LATTES makes it a powerful tool to detect transient phenomena and perform long term observations of variable sources. Moreover, given its characteristics, it would be fully complementary to the planned Cherenkov Telescope Array (CTA) as it would be able to issue alerts. In this talk, a description of its main features and capabilities, as well as results on its expected performance, and sensitivity, will be presented.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC2017), Busan, South Korea. Presented by R. Concei\c{c}\~{a}o. 8 pages; v2: correct affiliation + journal referenc

LATTES: A new gamma-ray detector concept for South America

Currently the detection of Very High Energy gamma-rays for astrophysics rely on the measurement of the Extensive Air Showers (EAS) either using Cherenkov detectors or EAS arrays with larger field of views but also larger energy thresholds. In this talk we present a novel hybrid detector concept for a EAS array with an improved sensitivity in the lower energies (~ 100 GeV). We discuss its main features, capabilities and present preliminary results on its expected perfomances and sensitivities.This wide field of view experiment is planned to be installed at high altitude in South America making it a complementary project to the planned Cherenkov telescope experiments and a powerful tool to trigger further observations of variable sources and to detect transients phenomena

Extracellular electrophysiological measurements of cooperative signals in astrocytes populations

Astrocytes are neuroglial cells that exhibit functional electrical properties sensitive to neuronal activity and capable of modulating neurotransmission. Thus, electrophysiological recordings of astroglial activity are very attractive to study the dynamics of glial signaling. This contribution reports on the use of ultra-sensitive planar electrodes combined with low noise and low frequency amplifiers that enable the detection of extracellular signals produced by primary cultures of astrocytes isolated from mouse cerebral cortex. Recorded activity is characterized by spontaneous bursts comprised of discrete signals with pronounced changes on the signal rate and amplitude. Weak and sporadic signals become synchronized and evolve with time to higher amplitude signals with a quasi-periodic behavior, revealing a cooperative signaling process. The methodology presented herewith enables the study of ionic fluctuations of population of cells, complementing the single cells observation by calcium imaging as well as by patch-clamp techniques.Portuguese Foundation for Science and Technology (FCT) [PTDC/EEI-AUT/5442/2014]; Instituto de Telecomunicacoes [UID/Multi/04326/2013]; Associated Laboratory - Institute of Nanoscience and Nanotechnology [POCI-01-0145-FEDER-016623]; [PTDC/CTM-NAN/3146/2014]info:eu-repo/semantics/publishedVersio

Experimental study of the sensitivity of a porous silicon ring resonator sensor using continuous in-flow measurements

A highly sensitive photonic sensor based on a porous silicon ring resonator was developed and experimentally characterized. The photonic sensing structure was fabricated by exploiting a porous silicon double layer, where the top layer of a low porosity was used to form photonic elements by e-beam lithography and the bottom layer of a high porosity was used to confine light in the vertical direction. The sensing performance of the ring resonator sensor based on porous silicon was compared for the different resonances within the analyzed wavelength range both for transverse-electric and transverse-magnetic polarizations. We determined that a sensitivity up to 439 nm/RIU for low refractive index changes can be achieved depending on the optical field distribution given by each resonance/polarization

Bimodal grating coupler design on SOI technology for mode division multiplexing at 1550 nm

© 2018 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited[EN] In this paper, we evaluate by means of simulation and experimentally the simultaneous coupling of the LP01x-LP11ax fiber modes and the TE0-TE1 nanophotonic SOI waveguide modes using a grating coupler for a two-mode fiber at 1550 nm. Both the grating width (ranging from 10 mu m to 15 mu m) and the grating vertical profile have been considered in the design procedure. The optimum design (14 mu m width and 609 nm grating period) has been selected in terms of coupling efficiency (both LP01x-TE0 and LP11ax-TE1), compactness and tolerance to lateral misalignments between fiber and coupler. The LP01x-TE0 and LP11ax-TE1 modes achieved coupling efficiencies of 49% and 45%, respectively. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing AgreementMinisterio de Economia y Competitividad (MINECO/FEDER) (TEC2015-70858-C2-1-R, RTC-2014-2232-3)García-Rodríguez, D.; Corral, JL.; Griol Barres, A.; Llorente, R. (2018). Bimodal grating coupler design on SOI technology for mode division multiplexing at 1550 nm. Optics Express. 26(15):19445-19455. https://doi.org/10.1364/OE.26.019445S19445194552615Richardson, D. J. (2016). New optical fibres for high-capacity optical communications. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 374(2062), 20140441. doi:10.1098/rsta.2014.0441Kasahara, M., Saitoh, K., Sakamoto, T., Hanzawa, N., Matsui, T., Tsujikawa, K., … Koshiba, M. (2013). Design of Few-Mode Fibers for Mode-Division Multiplexing Transmission. IEEE Photonics Journal, 5(6), 7201207-7201207. doi:10.1109/jphot.2013.2292365Chen, H., Sleiffer, V., Snyder, B., Kuschnerov, M., van Uden, R., Jung, Y., … Koonen, T. (2013). Demonstration of a Photonic Integrated Mode Coupler With MDM and WDM Transmission. IEEE Photonics Technology Letters, 25(21), 2039-2042. doi:10.1109/lpt.2013.2280669Sun, C., Yu, Y., Ye, M., Chen, G., & Zhang, X. (2016). An ultra-low crosstalk and broadband two-mode (de)multiplexer based on adiabatic couplers. Scientific Reports, 6(1). doi:10.1038/srep38494Xing, J., Li, Z., Xiao, X., Yu, J., & Yu, Y. (2013). Two-mode multiplexer and demultiplexer based on adiabatic couplers. Optics Letters, 38(17), 3468. doi:10.1364/ol.38.003468Garcia-Rodriguez, D., Corral, J. L., Griol, A., & Llorente, R. (2017). Dimensional variation tolerant mode converter/multiplexer fabricated in SOI technology for two-mode transmission at 1550  nm. Optics Letters, 42(7), 1221. doi:10.1364/ol.42.001221Garcia-Rodriguez, D., Corral, J. L., & Llorente, R. (2017). Mode Conversion for Mode Division Multiplexing at 850 nm in Standard SMF. IEEE Photonics Technology Letters, 29(11), 929-932. doi:10.1109/lpt.2017.2694605Zhang, Z., Hu, X., & Wang, J. (2015). On-chip optical mode exchange using tapered directional coupler. Scientific Reports, 5(1). doi:10.1038/srep16072Ding, Y., Xu, J., Da Ros, F., Huang, B., Ou, H., & Peucheret, C. (2013). On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer. Optics Express, 21(8), 10376. doi:10.1364/oe.21.010376Zanzi, A., Brimont, A., Griol, A., Sanchis, P., & Marti, J. (2016). Compact and low-loss asymmetrical multimode interference splitter for power monitoring applications. Optics Letters, 41(2), 227. doi:10.1364/ol.41.000227Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2013). Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission. Optics Express, 21(22), 25752. doi:10.1364/oe.21.025752Lai, Y., Yu, Y., Fu, S., Xu, J., Shum, P. P., & Zhang, X. (2017). Efficient spot size converter for higher-order mode fiber-chip coupling. Optics Letters, 42(18), 3702. doi:10.1364/ol.42.003702Hatori, N., Shimizu, T., Okano, M., Ishizaka, M., Yamamoto, T., Urino, Y., … Arakawa, Y. (2014). A Hybrid Integrated Light Source on a Silicon Platform Using a Trident Spot-Size Converter. Journal of Lightwave Technology, 32(7), 1329-1336. doi:10.1109/jlt.2014.2304305Hanzawa, N., Saitoh, K., Sakamoto, T., Matsui, T., Tsujikawa, K., Koshiba, M., & Yamamoto, F. (2014). Mode multi/demultiplexing with parallel waveguide for mode division multiplexed transmission. Optics Express, 22(24), 29321. doi:10.1364/oe.22.029321Dai, D., & Mao, M. (2015). Mode converter based on an inverse taper for multimode silicon nanophotonic integrated circuits. Optics Express, 23(22), 28376. doi:10.1364/oe.23.028376Taillaert, D., Van Laere, F., Ayre, M., Bogaerts, W., Van Thourhout, D., Bienstman, P., & Baets, R. (2006). Grating Couplers for Coupling between Optical Fibers and Nanophotonic Waveguides. Japanese Journal of Applied Physics, 45(8A), 6071-6077. doi:10.1143/jjap.45.6071Lardenois, S., Pascal, D., Vivien, L., Cassan, E., Laval, S., Orobtchouk, R., … Mollard, L. (2003). Low-loss submicrometer silicon-on-insulator rib waveguides and corner mirrors. Optics Letters, 28(13), 1150. doi:10.1364/ol.28.001150Orobtchouk, R., Layadi, A., Gualous, H., Pascal, D., Koster, A., & Laval, S. (2000). High-efficiency light coupling in a submicrometric silicon-on-insulator waveguide. Applied Optics, 39(31), 5773. doi:10.1364/ao.39.005773Wohlfeil, B., Rademacher, G., Stamatiadis, C., Voigt, K., Zimmermann, L., & Petermann, K. (2016). A Two-Dimensional Fiber Grating Coupler on SOI for Mode Division Multiplexing. IEEE Photonics Technology Letters, 28(11), 1241-1244. doi:10.1109/lpt.2016.2514712Koonen, A. M. J., Haoshuo Chen, van den Boom, H. P. A., & Raz, O. (2012). Silicon Photonic Integrated Mode Multiplexer and Demultiplexer. IEEE Photonics Technology Letters, 24(21), 1961-1964. doi:10.1109/lpt.2012.2219304Ding, Y., Ou, H., Xu, J., & Peucheret, C. (2013). Silicon Photonic Integrated Circuit Mode Multiplexer. IEEE Photonics Technology Letters, 25(7), 648-651. doi:10.1109/lpt.2013.2247394Galan, J. V., Sanchis, P., Blasco, J., & Marti, J. (2008). Study of High Efficiency Grating Couplers for Silicon-Based Horizontal Slot Waveguides. IEEE Photonics Technology Letters, 20(12), 985-987. doi:10.1109/lpt.2008.923546Roelkens, G., Van Thourhout, D., & Baets, R. (2006). High efficiency Silicon-on-Insulator grating coupler based on a poly-Silicon overlay. Optics Express, 14(24), 11622. doi:10.1364/oe.14.01162