Downgrading Recent Estimates of Land Available for Biofuel Production

Recent estimates of additional land available for bioenergy production range from 320 to 1411 million ha. These estimates were generated from four scenarios regarding the types of land suitable for bioenergy production using coarse-resolution inputs of soil productivity, slope, climate, and land cover. In this paper, these maps of land availability were assessed using high-resolution satellite imagery. Samples from these maps were selected and crowdsourcing of Google Earth images was used to determine the type of land cover and the degree of human impact. Based on this sample, a set of rules was formulated to downward adjust the original estimates for each of the four scenarios that were previously used to generate the maps of land availability for bioenergy production. The adjusted land availability estimates range from 56 to 1035 million ha depending upon the scenario and the ruleset used when the sample is corrected for bias. Large forest areas not intended for biofuel production purposes were present in all scenarios. However, these numbers should not be considered as definitive estimates but should be used to highlight the uncertainty in attempting to quantify land availability for biofuel production when using coarse-resolution inputs with implications for further policy development

First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring

The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 106 M ⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication

Multichromophoric calix[4]arenes: Effect of interchromophore distances on linear and nonlinear optical properties

Multichromophoric calix[4]arenes with two or four disperse red one (DR1) moieties linked to the lower rim have been synthesized. The second-order nonlinear optical activity was measured by using the electric-field-induced second-harmonic generation technique and there was a nearly linear increase of the μβ value with the number of chromophores in the molecule without affecting the charge-transfer absorption wavelength. The effect that the number of DR1 units plays on the hyperpolarizability, the dipole moment, and the absorption maxima has been also studied by using quantum chemical calculations. It was found that it was necessary to synthesize multichromophores with distant chromophores to obtain large nonlinear optical responses. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinm.Financial support from MEC-FEDER (CTQ2008-02942, CTQ2011-22727, MAT2008-06522-C02-02) and Gobierno de Aragón-Fondo Social Europeo (E39 and E04) is gratefully acknowledged.Peer Reviewe

Downgrading Recent Estimates of Land Available for Biofuel Production

Recent estimates of additional land available for bioenergy production range from 320 to 1411 million ha. These estimates were generated from four scenarios regarding the types of land suitable for bioenergy production using coarse-resolution inputs of soil productivity, slope, climate, and land cover. In this paper, these maps of land availability were assessed using high-resolution satellite imagery. Samples from these maps were selected and crowdsourcing of Google Earth images was used to determine the type of land cover and the degree of human impact. Based on this sample, a set of rules was formulated to downward adjust the original estimates for each of the four scenarios that were previously used to generate the maps of land availability for bioenergy production. The adjusted land availability estimates range from 56 to 1035 ha depending upon the scenario and the ruleset used when the sample is corrected for bias. Large forest areas not intended for biofuel production purposes were present in all scenarios. However, these numbers should not be considered as definitive estimates but should be used to highlight the uncertainty in attempting to quantify land availability for biofuel production when using coarse-resolution inputs with implications for further policy development

Downgrading recent estimates of land available for biofuel production

Recent estimates of additional land available for bioenergy production range from 320 to 1411 million ha. These estimates were generated from four scenarios regarding the types of land suitable for bioenergy production using coarse-resolution inputs of soil productivity, slope, climate, and land cover. In this paper, these maps of land availability were assessed using high-resolution satellite imagery. Samples from these maps were selected and crowdsourcing of Google Earth images was used to determine the type of land cover and the degree of human impact. Based on this sample, a set of rules was formulated to downward adjust the original estimates for each of the four scenarios that were previously used to generate the maps of land availability for bioenergy production. The adjusted land availability estimates range from 56 to 1035 million ha depending upon the scenario and the ruleset used when the sample is corrected for bias. Large forest areas not intended for biofuel production purposes were present in all scenarios. However, these numbers should not be considered as definitive estimates but should be used to highlight the uncertainty in attempting to quantify land availability for biofuel production when using coarse-resolution inputs with implications for further policy development.Fil: Fritz, Stephen. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: See, Linda. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: van der Velde, Marijn. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Nalepa, Rachel A.. Boston University; Estados UnidosFil: Perger, Christoph. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Schill, Christian. Universitàdi Modena e Reggio Emilia. Dipartimento di Scienze delle Terra; ItaliaFil: McCallum, Ian. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Dmitry Schepaschenko. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Kraxner, Florian. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Cai, Ximing. University of Illinois at Urbana; Estados UnidosFil: Zhang, Xiao. University of Illinois at Urbana; Estados UnidosFil: Ortner, Simone. University of Applied Sciences; AustriaFil: Hazarika, Rubul. Gauhati University; IndiaFil: Cipriani, Anna. Universitàdi Modena e Reggio Emilia. Dipartimento di Scienze delle Terra; Italia. Columbia University; Estados UnidosFil: Di Bella, Carlos Marcelo. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rabia, Ahmed H.. Università degli Studi di Napoli Federico II; ItaliaFil: García, Alfredo Gabriel. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vakolyuk, Mar'yana. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Singha, Kuleswar. Gauhati University; IndiaFil: Beget, María Eugenia. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Erasmi, Stefan. Universität Göttingen; AlemaniaFil: Albrecht, Franziska. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Shaw, Brian. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; AustriaFil: Obersteiner, Michael. International Institute of Applied Systems Analysis. Ecosystem Services and Management Program; Austri