Natural history of Belonuchus Nordmann spp. and allies (Coleoptera: Staphylinidae) in Heliconia L. (Zingiberales: Heliconiaceae) flower bracts

Adults, and in some species larvae, of several members of Belonuchus Nordmann (Coleoptera: Staphylinidae: Staphylininae) and a few related genera seem to be to various degrees consistently associated with flower bracts of the genus Heliconia (Zingiberales: Heliconiaceae). They are predators and eat various dipterous and lepidopterous larvae in that habitat. Adults of at least Belonuchus cephalotes (Sharp) and Odontolinus fasciatus Sharp are able to immerse completely in water to capture larvae and/or pupae of mosquitoes (Culicidae). Adults and larvae of Belonuchus satyrus Erichson, and adults of B. cacao Blackwelder and B. rufipennis (F.) were found in water-filled flower bracts of Heliconia bihai (L.) L. in northern, lowland Venezuela. The bracts also contained mosquito larvae and semiaquatic coleopterous (Chrysomelidae: Hispinae), lepidopterous (Crambidae: Pyraustinae) and dipterous (Syrphidae, Stratiomyidae, Psychodidae, Richardiidae) larvae, and Annelida. In feeding trials, B. satyrus adults and larvae did not feed on hispine larvae or annelids, but did feed on all the lepidopterous and dipterous larvae available to them; adults dragged larvae and pupae of the mosquito genus Toxorhynchites Theobald from shallow water and thus seemed to be the top predators of the food pyramid within bracts. Records are compiled of association of Belonuchus and relatives with Heliconia bracts in the neotropics. We correct the names used for Heliconia spp. by earlier entomological authors working in Venezuela. Their ‘Heliconia caribaea Lamarck’ is H. bihai (L.) L. and their ‘H. aurea Rodríguez’ is H. bihai cv. Aurea.Los adultos y en algunos casos también las larvas de varias especies de Belonuchus spp. (Coleoptera: Staphylinidae: Staphylininae) y algunos géneros relacionados están consistentemente asociados con las espatas florales del género Heliconia (Zingiberales: Heliconiaceae). Estos coleópteros son depredadores y comen larvas de varios tipos de dípteros y lepidópteros en ese hábitat. Los adultos de Belonuchus cephalotes (Sharp) y Odontolinus fasciatus Sharp pueden sumergirse completamente en el agua para capturar las larvas y pupas de mosquitos (Culicidae). Larvas y adultos de Belonuchus satyrus Erichson, así como adultos de B. cacao Blackwelder y B. rufipennis (F.) fueron encontrados en las brácteas florales de Heliconia bihai (L.) L. de las partes bajas del norte de Venezuela. Las brácteas también contenían larvas de mosquitos y coleópteros semi-acuáticos (Chrysomelidae: Hispinae), larvas de lepidópteros (Crambidae: Pyraustinae) y de dípteros (Syrphidae, Stratiomyidae, Psychodidae, Richardiidae), y anélidos. En experimentos de alimentación, las larvas y los adultos de B. satyrus no se alimentaron de larvas de Hispinae ni de anélidos, sin embargo todas las larvas de lepidópteros y de dípteros que se les ofrecieron fueron ingeridas; los adultos de B. satyrus también extraen larvas de mosquitos del género Toxorhynchites Theobald del agua, por lo cual parecen ser los depredadores del tope de la pirámide alimentaria en las brácteas. Los registros de asociaciones de Belonuchus y géneros afines con las brácteas de Heliconia en el Neotrópico fueron recopiladas. Corregimos los nombres de Heliconia spp.utilizados anteriormente por entomólogos que trabajaron en Venezuela. Su ‘Heliconia caribaea Lamarck’ corresponde a H. bihai (L.) L. y su ‘H. aurea Rodríguez’ corresponde a H. bihai cv. Aurea

Local Cohomology: Combinatorics and D-Modules

In this thesis, we study combinatorial and D-module theoretic aspects of local cohomology. Viewing local cohomology from the point of view of A-hypergeometric systems, the quasidegree set of the non-top local cohomology modules supported at the maximal ideal m of a toric ideal determine parameters β where the rank of the corresponding hypergeometric system is higher than expected. We discuss the Macaulay2 package, Quasidegrees, and its main functions. The main purpose of Quasidegrees is to compute where the rank of the solution space of an A-hypergeometric system is higher than expected. Local duality gives a vector space isomorphism between local cohomology and Ext-modules. However, the proof of local duality is nonconstructive. We recall a combinatorial construction by Irena Peeva and Bernd Sturmfels to minimally resolve codimension 2 lattice ideals. With motivation coming from A-hypergeometric systems, we use the construction by Peeva and Sturmfels to construct an explicit local duality isomorphism for codimension 2 lattice ideals. In general, local cohomology modules of a ring may not be finitely generated. However, they still may possess other finiteness properties. In 1990, Craig Huneke asked if the number of associated prime ideals of a local cohomology module is finite. Using characteristic free D-module techniques inspired by Glennady Lyubeznik, we answer Huneke's question in the affirmative for local cohomology modules over Stanley-Reisner rings

Cryptographic salting for security enhancement of double random phase encryption schemes

Security in optical encryption techniques is a subject of great importance, especially in light of recent reports of successful attacks. We propose a new procedure to reinforce the ciphertexts generated in double random phase encrypting experimental setups. This ciphertext is protected by multiplexing with a 'salt' ciphertext coded with the same setup. We present an experimental implementation of the 'salting' technique. Thereafter, we analyze the resistance of the 'salted' ciphertext under some of the commonly known attacks reported in the literature, demonstrating the validity of our proposal.Fil: Velez Zea, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Barrera Ramírez, John Fredy. Universidad de Antioquia; ColombiaFil: Torroba, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina. Universidad Nacional de la Plata. Facultad de Ingeniería. Uidet Grupo de Ensayos Mecanicos Aplicados.; Argentin

On critical values of L-functions of potentially automorphic motives

In this paper we prove a version of Deligne's conjecture for potentially automorphic motives, twisted by certain algebraic Hecke characters. The Hecke characters are chosen in such a way that we can use automorphic methods in the context of totally definite unitary groups.Postprint (author's final draft

Multiplexing of encrypted data using fractal masks

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.002895. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under lawIn this Letter, we present to the best of our knowledge a new all-optical technique for multiple-image encryption and multiplexing, based on fractal encrypting masks. The optical architecture is a joint transform correlator. The multiplexed encrypted data are stored in a photorefractive crystal. The fractal parameters of the key can be easily tuned to lead to a multiplexing operation without cross talk effects. Experimental results that support the potential of the method are presented.This research was performed under grants TWAS-UNESCO Associateship Scheme at Centres of Excellence in the South, CONICET No. 0863 (Argentina), ANCYT PICT 1167 (Argentina), and Facultad de Ingenieria, Universidad Nacional de La Plata No. 11/I125 (Argentina), Sostenibilidad 2011-2012, and CODI (Universidad de Antioquia-Colombia). W. D. Furlan and J. A. Monsoriua acknowledge financial support from Ministerio de Economia y Competitividad (grant FIS2011-23175), Generalitat Valenciana (grant PROMETEO2009-077), and Universitat Politecnica de Valencia (grants PAID-05-11 and PAID-02-11), Spain.Barrera, J.; Tebaldi, M.; Amaya, D.; Furlan, W.; Monsoriu Serra, JA.; Bolognini, NA.; Torroba, RD.... (2012). Multiplexing of encrypted data using fractal masks. Optics Letters. 37(14):2895-2897. doi:10.1364/OL.37.002895S289528973714Refregier, P., & Javidi, B. (1995). Optical image encryption based on input plane and Fourier plane random encoding. Optics Letters, 20(7), 767. doi:10.1364/ol.20.000767Matoba, O., & Javidi, B. (1999). Encrypted optical memory system using three-dimensional keys in the Fresnel domain. Optics Letters, 24(11), 762. doi:10.1364/ol.24.000762Unnikrishnan, G., Joseph, J., & Singh, K. (2000). Optical encryption by double-random phase encoding in the fractional Fourier domain. Optics Letters, 25(12), 887. doi:10.1364/ol.25.000887Nomura, T. (2000). Polarization encoding for optical security systems. Optical Engineering, 39(9), 2439. doi:10.1117/1.1288369Tebaldi, M., Furlan, W. D., Torroba, R., & Bolognini, N. (2009). Optical-data storage-readout technique based on fractal encrypting masks. Optics Letters, 34(3), 316. doi:10.1364/ol.34.000316Situ, G., & Zhang, J. (2005). Multiple-image encryption by wavelength multiplexing. Optics Letters, 30(11), 1306. doi:10.1364/ol.30.001306Liu, Z., & Liu, S. (2007). Double image encryption based on iterative fractional Fourier transform. Optics Communications, 275(2), 324-329. doi:10.1016/j.optcom.2007.03.039Hwang, H.-E., Chang, H. T., & Lie, W.-N. (2009). Multiple-image encryption and multiplexing using a modified Gerchberg-Saxton algorithm and phase modulation in Fresnel-transform domain. Optics Letters, 34(24), 3917. doi:10.1364/ol.34.003917Matoba, O., & Javidi, B. (1999). Encrypted optical storage with angular multiplexing. Applied Optics, 38(35), 7288. doi:10.1364/ao.38.007288Fredy Barrera, J., Henao, R., Tebaldi, M., Torroba, R., & Bolognini, N. (2006). Multiplexing encryption–decryption via lateral shifting of a random phase mask. Optics Communications, 259(2), 532-536. doi:10.1016/j.optcom.2005.09.027Henao, R., Rueda, E., Barrera, J. F., & Torroba, R. (2010). Noise-free recovery of optodigital encrypted and multiplexed images. Optics Letters, 35(3), 333. doi:10.1364/ol.35.000333Barrera, J. F., Henao, R., Tebaldi, M., Torroba, R., & Bolognini, N. (2006). Multiple image encryption using an aperture-modulated optical system. Optics Communications, 261(1), 29-33. doi:10.1016/j.optcom.2005.11.055Mosso, F., Barrera, J. F., Tebaldi, M., Bolognini, N., & Torroba, R. (2011). All-optical encrypted movie. Optics Express, 19(6), 5706. doi:10.1364/oe.19.005706Monsoriu, J. A., Saavedra, G., & Furlan, W. D. (2004). Fractal zone plates with variable lacunarity. Optics Express, 12(18), 4227. doi:10.1364/opex.12.00422

Dynamic hedging of prices of Natural Gas in Mexico

The first-hand sale prices of Natural Gas (NG) in Mexico had a dynamic lagged relationship with international NG futures prices during the period of January 2012 to June 2017. Based on a hedging strategy which includes NG futures and using an MGARCH VCC model, conditional variances were estimated with 20 and 40 days of lag between the prices of NG Futures. Dynamic hedges of NG were calculated assuming theoretical futures prices of the US dollar in Mexican pesos. With the use of backtesting, it was found that the forecasts of optimal hedge ratios improve with short prediction periods and proximate observed data. The dynamic hedging model proposed can be extended to other fuel markets. The importance of hedging NG prices derives from the size of the market and the extent of the risks to which the market participants are exposed.(Cobertura dinámica de precios del Gas Natural en México)Los precios de venta de primera mano del gas natural (GN) en México tuvieron una relación dinámica, pero con retrasos, con los precios internacionales de los futuros de GN durante el periodo de enero de 2012 a junio de 2017. A partir de una estrategia de cobertura en la que se emplean futuros de GN y utilizando un modelo MGARCH VCC para estimar las variaciones condicionales con retrasos de 20 y 40 días de los precios de los futuros, se muestra cómo se comportan las coberturas dinámicas de GN, suponiendo precios teóricos futuros del dólar estadounidense en pesos mexicanos. A través de una prueba retrospectiva, se halló que las predicciones de las razones de cobertura óptima mejoran con períodos cortos de pronóstico y períodos cercanos de observación. El modelo de cobertura dinámica propuesto puede extenderse a otros mercados de combustibles. Se destaca la importancia de la cobertura de los precios del GN dado el tamaño del mercado y la magnitud del riesgo al que se encuentran expuestos los participantes