Instituto Politécnico Nacional

About: Instituto Politécnico Nacional is a education organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Population & Context (language use). The organization has 43351 authors who have published 63315 publications receiving 938532 citations. The organization is also known as: Instituto Politécnico Nacional & Instituto Politecnico Nacional.

Fermi Gamma-ray Space Telescope observations of the gamma-ray outburst from 3C454.3 in November 2010

Abstract: The flat-spectrum radio quasar 3C454.3 underwent an extraordinary 5 day γ -ray outburst in 2010 November when the daily flux measured with the Fermi Large Area Telescope (LAT) at photon energies E > 100 MeV reached (66 ± 2) × 10−6 photons cm−2 s−1. This is a factor of three higher than its previous maximum flux recorded in 2009 December and 5 times brighter than the Vela pulsar, which is normally the brightest source in the γ -ray sky. The 3 hr peak flux was (85 ± 5)×10−6 photons cm−2 s−1, corresponding to an apparent isotropic luminosity of (2.1 ± 0.2)×1050 erg s−1, the highest ever recorded for a blazar. In this Letter, we investigate the features of this exceptional event in the γ -ray band of the Fermi-LAT. In contrast to previous flares of the same source observed with the Fermi-LAT, clear spectral changes are observed during the flare.

Nonlinear observer design to synchronize hyperchaotic systems via a scalar signal

Abstract: In this work control theory is used to formalize hyperchaos synchronization as a nonlinear observer design issue. Following this approach, a new systematic tool to synchronize a class of hyperchaotic systems via a scalar transmitted signal is developed. The proposed technique has been applied to synchronize two well-known hyperchaotic systems.

Carbon Stocks of Tropical Coastal Wetlands within the Karstic Landscape of the Mexican Caribbean

Abstract: Coastal wetlands can have exceptionally large carbon (C) stocks and their protection and restoration would constitute an effective mitigation strategy to climate change. Inclusion of coastal ecosystems in mitigation strategies requires quantification of carbon stocks in order to calculate emissions or sequestration through time. In this study, we quantified the ecosystem C stocks of coastal wetlands of the Sian Ka'an Biosphere Reserve (SKBR) in the Yucatan Peninsula, Mexico. We stratified the SKBR into different vegetation types (tall, medium and dwarf mangroves, and marshes), and examined relationships of environmental variables with C stocks. At nine sites within SKBR, we quantified ecosystem C stocks through measurement of above and belowground biomass, downed wood, and soil C. Additionally, we measured nitrogen (N) and phosphorus (P) from the soil and interstitial salinity. Tall mangroves had the highest C stocks (987±338 Mg ha(-1)) followed by medium mangroves (623±41 Mg ha(-1)), dwarf mangroves (381±52 Mg ha(-1)) and marshes (177±73 Mg ha(-1)). At all sites, soil C comprised the majority of the ecosystem C stocks (78-99%). Highest C stocks were measured in soils that were relatively low in salinity, high in P and low in N∶P, suggesting that P limits C sequestration and accumulation potential. In this karstic area, coastal wetlands, especially mangroves, are important C stocks. At the landscape scale, the coastal wetlands of Sian Ka'an covering ≈172,176 ha may store 43.2 to 58.0 million Mg of C.