Time-dependent modeling of TeV-detected, young pulsar wind nebulae

The increasing sensitivity of instruments at X-ray and TeV energies have revealed a large number of nebulae associated with bright pulsars. Despite this large data set, the observed pulsar wind nebulae (PWNe) do not show a uniform behavior and the main parameters driving features like luminosity, magnetization, and others are still not fully understood. To evaluate the possible existence of common evolutive trends and to link the characteristics of the nebula emission with those of the powering pulsar, we selected a sub-set of 10 TeV detections which are likely ascribed to young PWNe and model the spectral energy distribution with a time-dependent description of the nebulae's electron population. In 9 of these cases, a detailed PWNe model, using up-to-date multiwavelength information, is presented. The best-fit parameters of these nebula are discussed, together with the pulsar characteristics. We conclude that TeV PWNe are particle-dominated objects with large multiplicities, in general far from magnetic equipartition, and that relatively large photon field enhancements are required to explain the high level of Comptonized photons observed. We do not find significant correlations between the efficiencies of emission at different frequencies and the magnetization. The injection parameters do not appear to be particularly correlated with the pulsar properties either. We find that a normalized comparison of the SEDs (e.g., with the corresponding spin-down flux) at the same age significantly reduces the spectral distributions dispersion.Comment: 38 pages, 20 figures, 8 tables. Accepted for publication in the Journal of High Energy Astrophysics (JHEAp

The effects of magnetic field, age, and intrinsic luminosity on Crab-like pulsar wind nebulae

We investigate the time-dependent behavior of Crab-like pulsar wind nebulae (PWNe) generating a set of models using 4 different initial spin-down luminosities ($L_0 =\{1,0.1,0.01,0.001\} \times L_{0, {\rm Crab}}$), 8 values of magnetic fraction ($\eta =$ 0.001, 0.01, 0.03, 0.1, 0.5, 0.9, 0.99, and 0.999, i.e., from fully particle dominated to fully magnetically dominated nebulae), and 3 distinctive ages: 940, 3000, and 9000 years. We find that the self-synchrotron Compton (SSC) contribution is irrelevant for $L_{SD}$=0.1, 1, and 10% of the Crab power, disregarding the age and the magnetic fraction. SSC only becomes relevant for highly energetic ($\sim 70$ of the Crab), particle dominated nebulae at low ages (of less than a few kyr), located in a FIR background with relatively low energy density. Since no pulsar other than Crab is known to have these features, these results clarify why the Crab Nebula, and only it, is SSC dominated. No young PWN would be detectable at TeV energies if the pulsar's spin-down power is 0.1% Crab or lower. For 1% of the Crab spin-down, only particle dominated nebulae can be detected by H.E.S.S.-like telescopes when young enough (with details depending on the precise injection and environmental parameters). Above 10% of the Crab's power, all PWNe are detectable by H.E.S.S.-like telescopes if they are particle dominated, no matter the age. The impact of the magnetic fraction on the final SED is varied and important, generating order of magnitude variations in the luminosity output for systems that are otherwise the same (equal $P$, $\dot P$, injection, and environment).Comment: Accepted for publication in MNRA

Is there room for highly magnetized pulsar wind nebulae among those non-detected at TeV?

We make a time-dependent characterization of pulsar wind nebulae (PWNe) surrounding some of the highest spin-down pulsars that have not yet been detected at TeV. Our aim is assessing their possible level of magnetization. We analyze the nebulae driven by J2022+3842 in G76.9+1.0, J0540-6919 in N158A (the Crab twin), J1400--6325 in G310.6--1.6, and J1124--5916 in G292.0+0.18, none of which have been found at TeV energies. For comparison we refer to published models of G54.1+0.3, the Crab nebula, and develop a model for N157B in the Large Magellanic Cloud (LMC). We conclude that further observations of N158A could lead to its detection at VHE. According to our model, a FIR energy density of 5 eV cm$^{-3}$ could already lead to a detection in H.E.S.S. (assuming no other IC target field) within 50 hours of exposure and just the CMB inverse Compton contribution would produce VHE photons at the CTA sensitivity. We also propose models for G76.9+1.0, G310.6--1.6 and G292.0+1.8 which suggest their TeV detection in a moderate exposure for the latter two with the current generation of Cherenkov telescopes. We analyze the possibility that these PWNe are highly magnetized, where the low number of particles explains the residual detection in X-rays and their lack of detection at TeV energies.Comment: Accepted for publication in MNRA

A proposal for cost-related and market-oriented train running charges

[EN] This paper examines some key aspects of a charging system for promoting railway transport, including charges reflecting a clear relationship with costs (transparency) and charges reflecting the quality of the infrastructure manager¿s service. Train running charges recover track-related costs and can help to develop a charging system that meets these requirements. To orient train running charges to the market, a method for processing track maintenance and renewal costs is proposed whereby the quality of the service provided by an infrastructure is measured according to its utility to the railway undertaking. To achieve transparency, a single indicator is used for cost planning and the subsequent levying of costs on railway undertakings. The paper includes an example of how proposed train running charges would be calculated according to data from 14 European countries. The example shows that short-distance trains generate the lowest maintenance and renewal costs, followed by long-distance trains and freight trains.This work was supported by the Spanish Ministerio de Fomento [grant number PT-2007-056-05CCPP].Calvo, F.; De Oña, J.; De Oña, R.; López-Maldonado, G.; Garach, L. (2014). A proposal for cost-related and market-oriented train running charges. Transportation Planning and Technology. 37(4):354-372. https://doi.org/10.1080/03081060.2014.897127S354372374Baumgartner, J. P. 2001. “Prices and Costs in the Railway Sector.” Laboratoire d'Intermodalité des Transports et de Planification. École Polytechnique Fédérale de Lausanne. Accessed February 4. http://litep.epfl.ch–2014Calvo, F., and J. de Oña. 2012a. “An Approach to Mark-Ups through Capacity Charges.”Proceedings of the ICE – Transport. Accessed February 4. http://www.icevirtuallibrary.com/content/article/10.1680/tran.11.00050.Calvo, F., & De Oña, J. (2012). Are rail charges connected to costs? Journal of Transport Geography, 22, 28-33. doi:10.1016/j.jtrangeo.2011.11.004Calvo, F., de Oña, J., López, G., Garach, L., & de Oña, R. (2013). Rail track costs management for efficient railway charges. Proceedings of the Institution of Civil Engineers - Transport, 166(6), 325-335. doi:10.1680/tran.11.00001Calvo, F., de Oña, J., & Nash, A. (2007). Proposed Infrastructure Pricing Methodology for Mixed-Use Rail Networks. Transportation Research Record: Journal of the Transportation Research Board, 1995(1), 9-16. doi:10.3141/1995-02CENIT, TIS PT, IWW, and HERRY. 2007. “RailCalc. Calculation of Charges for the Use of Rail Infrastructure.” Prepared for the European Commission Directorate General for Energy and Transport. Accessed February 4. http://ec.europa.eu/transport/rail/legislation/doc/railcalc_discussion_paper_final.pdf.ECMT (European Conference of Ministers of Transport). 2005. “Charges for the Use of Infrastructure in ECMT Railways.” Draft final report. ECMT/CS/CF(2005)1/REV1. Accessed February 4. http://lnweb90.worldbank.org/ECA/Transport.nsf/ECADocByUnid/2CF8BE276F63A37D85256FB20043A05D?Opendocument.EPFL (Ecole Polytechnique Féderale de Lausanne). 2003. “IMPROVERAIL: IMPROVEd Tools for RAILway Capacity and Access Management.” Accessed February 4. http://litep.epfl.ch.Network Rail. 2006. “Usage Costs – Assessment Methodology.” Draft for consultation. Accessed February 4. http://www.networkrail.co.uk/browse%20documents/regulatory%20documents/access%20charges%20reviews/consultations%20on%20future%20charging/variable%20track%20access%20charges/g-%20usage%20costs%20methodology%20sept%2006.pdf.Nyström, B., & Söderholm, P. (2010). Selection of maintenance actions using the analytic hierarchy process (AHP): decision-making in railway infrastructure. Structure and Infrastructure Engineering, 6(4), 467-479. doi:10.1080/15732470801990209ORR (Office of Rail Regulation). 2005. “Revision of Variable Usage and Electrification Asset Usage Charges: Final Report.” Accessed February 4. http://www.rail-reg.gov.uk/upload/pdf/bah_variable-usage-initial-report_jan05.pdf.Quinet, E. (2003). Short term adjustments in rail activity: the limited role of infrastructure charges. Transport Policy, 10(1), 73-79. doi:10.1016/s0967-070x(02)00047-1Thomas, J. 2002. “EU Task Force on Rail Infrastructure Charging: Summary Findings on Best Practice in Marginal Cost Pricing.” IMPRINT-EUROPE. Implementing Reform in Transport. Effective Use of Research on Pricing in Europe. A European Commission-funded Thematic Network (2001–2004). Accessed February 4. www.imprint-eu.org/public/Presentations/imprint3_Thomas.ppt.UIC (International Union of Railways). 2008. “Lasting Infrastructure Cost Benchmarking (LICB).” Summary Report. Accessed February 4. http://www.uic.org/spip.php?article582

CTA and cosmic-ray diffusion in molecular clouds

Molecular clouds act as primary targets for cosmic-ray interactions and are expected to shine in gamma-rays as a by-product of these interactions. Indeed several detected gamma-ray sources both in HE and VHE gamma-rays (HE: 100 MeV < E 100 GeV) have been directly or indirectly associated with molecular clouds. Information on the local diffusion coefficient and the local cosmic-ray population can be deduced from the observed gamma-ray signals. In this work we concentrate on the capability of the forthcoming Cherenkov Telescope Array Observatory (CTA) to provide such measurements. We investigate the expected emission from clouds hosting an accelerator, exploring the parameter space for different modes of acceleration, age of the source, cloud density profile, and cosmic ray diffusion coefficient. We present some of the most interesting cases for CTA regarding this science topic. The simulated gamma-ray fluxes depend strongly on the input parameters. In some cases, from CTA data it will be possible to constrain both the properties of the accelerator and the propagation mode of cosmic rays in the cloud.Comment: In Proceedings of the 2012 Heidelberg Symposium on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184

Drying Kinetics of Oca (Oxalis Tuberosa)

One of the most important steps for agro-industrial industrialization is examining the kinetic behavior of products, to determine the ideal parameters to maintain their characteristics throughout the production chain. This study experimentally determined the drying kinetics of oca, an indigenous product of the Andean region, because there is no established information on the drying techniques of this tuber. The Andean region is the cradle of a large number of food crops that were domesticated and exploited by indigenous people thousands of years ago, even long before the expansion of the Inca civilization. In Ecuador, oca is perhaps the most important element of the daily diet, and an acceptable level of purity and hygiene has been reached. Oca provides fiber, essential amino acids and a low level of fat. In this study, a temperature of 60ºC was set at the beginning of each experimental run. The weight of the oca slices was measured every 10 min. The experiments were carried out in triplicate. Data were analyzed using StatGraphics software. Two drying periods were observed: the initial period of constant drying speed, where the removal of moisture corresponded to moisture not linked to the oca, while in the second stage, the internal moisture of the tuber was removed. Keywords: kinetic, drying, goose. RESUMEN Uno de los pasos más importantes para la industrialización agroindustrial es el comportamiento cinético de productos, esto en especial para conocer cuáles son los parámetros ideales para mantener las características sensoriales durante toda la cadena de producción. El presente documento determina experimentalmente la cinética de secado para un producto autóctono de la Región Andina, como lo es la oca, puesto que no existe información sobre las técnicas de secado de este tubérculo. En el Ecuador se ha alcanzado un aceptable nivel de pureza e higiene, la Oca es quizás el elemento más importante de la dieta diaria. La región andina es cuna de un gran número de cultivos alimenticios que fueron domesticados y aprovechados por pueblos autóctonos hace miles de años, inclusive mucho antes de la expansión de la civilización Inca. Aporta fibra, aminoácidos esenciales y un nivel bajo en grasa. La experimentación para conocer las curvas que modelan el comportamiento cinético del secado, se llevó a cabo por triplicado; luego de realizar la recolección de datos, estos fueron analizados utilizando el software estadístico StatGraphics. donde se obtuvo el respectivo análisis de varianza y las curvas. En el estudio se configuró una temperatura de 60ºC al inicio de cada corrida experimental, Se midió el peso de las rodajas de Oca cada 10 min, los datos fueron registrados y se procesó las tablas resultantes. En el estudio se pudo observar dos periodos de secado: Periodo inicial de velocidad de secado constante, donde la eliminación de humedad corresponde a la humedad no ligada a la oca, mientras en la segunda etapa se eliminó la humedad interna del tubérculo. Palabras claves: cinética, secado, oca

Evaluation of interindividual and intraindividual variability in basketball jump throws through biomechanical analysis

El objetivo del presente estudio ha sido cuantificar las diferencias en la ejecución del lanzamiento en salto analizando la variabilidad intrasujetos e intersujetos. En la mayoría de las investigaciones, donde se pretende estudiar un gesto deportivo desde el punto de vista biomecánico, se selecciona el mejor intento, determinado por el rendimiento obtenido en términos de distancia o altura alcanzada del lanzamiento, descartándose la posibilidad de intravariabilidad entre ensayos. Sin embargo, este aspecto de variabilidad, no debe ser del todo olvidado en gestos como el lanzamiento en salto baloncesto, donde las condiciones contextuales de su aplicación se modifican constantemente durante la competición y donde la variabilidad intrasujeto podría aportarnos mayor conocimiento de este gesto. La muestra ha estado compuesta por jugadores profesionales de baloncesto pertenecientes a la liga ACB, utilizando la fotogrametría tridimensional para el análisis del gesto. Los resultados obtenidos, indican que la intervariabilidad es mayor que la intravariabilidad en todas las variables cinemáticas analizadas.Peer Reviewe

Context and prediction matter for the interpretation of social interactions across species

Predictions about others’ future actions are crucial during social interactions, in order to react optimally. Another way to assess such interactions is to define the social context of the situations explicitly and categorize them according to their affective content. Here we investigate how humans assess aggressive, playful and neutral interactions between members of three species: human children, dogs and macaques. We presented human participants with short video clips of real-life interactions of dyads of the three species and asked them either to categorize the context of the situation or to predict the outcome of the observed interaction. Participants performed above chance level in assessing social situations in humans, in dogs and in monkeys. How accurately participants predicted and categorized the situations depended both on the species and on the context. Contrary to our hypothesis, participants were not better at assessing aggressive situations than playful or neutral situations. Importantly, participants performed particularly poorly when assessing aggressive behaviour for dogs. Also, participants were not better at assessing social interactions of humans compared to those of other species. We discuss what mechanism humans use to assess social situations and to what extent this skill can also be found in other social species.Introduction Methods - Subjects - Stimuli - Procedure - Design and coding - Statistical analyses Results - Context decisions - Outcome decisions - Comparison between context and outcome decisions Discussio

Estimating Galactic gas content using different tracers: Compatibility of results, dark gas, and unidentified TeV sources

A large fraction of Galactic very-high energy (VHE; E$\gtrsim$100 GeV) $\gamma$-ray sources is cataloged as unidentified. In this work we explore the possibility that these unidentified sources are located in ambients particularly rich in material content unaccounted by traditional tracers. In a scenario where the VHE emission is due to the interaction of the accelerated particles with a target mass, a large mass of untraced material could be substantially contributing to the VHE emission from these regions. Here, we use three tracers for the commonly explored components: intensity of the $^\textrm{12}$CO(1$\rightarrow$0) line to trace the molecular material, HI hyperfine transition at 21cm to trace atomic hydrogen, and dust emission to trace the total hydrogen content. We show that the estimates of material content from these three tracers are compatible if the uncertainty on the respective conversion factors is taken into account. No additional gas component is found in these regions. However, a simple mass estimation from the $^\textrm{12}$CO(1$\rightarrow$0) line intensity might underestimate the total mass component in some locations.Comment: 9 pages, 4 figures, accepted for publication in JHEA

Testing source confusion and identification capability in Cherenkov Telescope Array data

The Cherenkov Telescope Array will provide the deepest survey of the Galactic Plane performed at very-high-energy gamma-rays. Consequently, this survey will unavoidably face the challenge of source confusion, i.e., the non-unique attribution of signal to a source due to multiple overlapping sources. Among the known populations of Galactic gamma-ray sources and given their extension and number, pulsar wind nebulae (PWNe, and PWN TeV halos) will be the most affected. We aim to probe source confusion of TeV PWNe in forthcoming CTA data. For this purpose, we performed and analyzed simulations of artificially confused PWNe with CTA. As a basis for our simulations, we applied our study to TeV data collected from the H.E.S.S. Galactic Plane Survey for ten extended and two point-like firmly identified PWNe, probing various configurations of source confusion involving different projected separations, relative orientations, flux levels, and extensions among sources. Source confusion, defined here to appear when the sum of the Gaussian width of two sources is larger than the separation between their centroids, occurred in $\sim$30% of the simulations. For this sample and 0.5$\deg$ of average separation between sources, we found that CTA can likely resolve up to 60% of those confused sources above 500 GeV. Finally, we also considered simulations of isolated extended sources to see how well they could be matched to a library of morphological templates. The outcome of the simulations indicates a remarkable capability (more than 95% of the cases studied) to match a simulation with the correct input template in its proper orientation.Comment: In press in MNRA