X-ray Absorption and Reflection in Active Galactic Nuclei

X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion process that fuels AGN and the feedback of material to their host galaxies. We describe the spectral signatures that may be studied and review the X-ray spectra and spectral variability of active galaxies, concentrating on progress from recent Chandra, XMM-Newton and Suzaku data for local type 1 AGN. We describe the evidence for absorption covering a wide range of column densities, ionization and dynamics, and discuss the growing evidence for partial-covering absorption from data at energies > 10 keV. Such absorption can also explain the observed X-ray spectral curvature and variability in AGN at lower energies and is likely an important factor in shaping the observed properties of this class of source. Consideration of self-consistent models for local AGN indicates that X-ray spectra likely comprise a combination of absorption and reflection effects from material originating within a few light days of the black hole as well as on larger scales. It is likely that AGN X-ray spectra may be strongly affected by the presence of disk-wind outflows that are expected in systems with high accretion rates, and we describe models that attempt to predict the effects of radiative transfer through such winds, and discuss the prospects for new data to test and address these ideas.Comment: Accepted for publication in the Astronomy and Astrophysics Review. 58 pages, 9 figures. V2 has fixed an error in footnote

Remote Sensing and Reflectance Profiling in Entomology

Remote sensing describes the characterization of the status of objects and/or the classification of their identity based on a combination of spectral features extracted from reflectance or transmission profiles of radiometric energy. Remote sensing can be benchtop based, and therefore acquired at a high spatial resolution, or airborne at lower spatial resolution to cover large areas. Despite important challenges, airborne remote sensing technologies will undoubtedly be of major importance in optimized management of agricultural systems in the twenty-first century. Benchtop remote sensing applications are becoming important in insect systematics and in phenomics studies of insect behavior and physiology. This review highlights how remote sensing influences entomological research by enabling scientists to nondestructively monitor how individual insects respond to treatments and ambient conditions. Furthermore, novel remote sensing technologies are creating intriguing interdisciplinary bridges between entomology and disciplines such as informatics and electrical engineering

Plant-water relationships in the Great Basin Desert of North America derived from Pinus monophylla hourly dendrometer records

Water is the main limiting resource for natural and human systems, but the effect of hydroclimatic variability on woody species in water-limited environments at sub-monthly time scales is not fully understood. Plant-water relationships of single-leaf pinyon pine (Pinus monophylla) were investigated using hourly dendrometer and environmental data from May 2006 to October 2011 in the Great Basin Desert, one of the driest regions of North America. Average radial stem increments showed an annual range of variation below 1.0 mm, with a monotonic steep increase from May to July that yielded a stem enlargement of about 0.5 mm. Stem shrinkage up to 0.2 mm occurred in late summer, followed by an abrupt expansion of up to 0.5 mm in the fall, at the arrival of the new water year precipitation. Subsequent winter shrinkage and enlargement were less than 0.3 mm each. Based on 4 years with continuous data, diel cycles varied in both timing and amplitude between months and years. Phase shifts in circadian stem changes were observed between the growing season and the dormant one, with stem size being linked to precipitation more than to other water-related indices, such as relative humidity or soil moisture. During May–October, the amplitude of the phases of stem contraction, expansion, and increment was positively related to their duration in a nonlinear fashion. Changes in precipitation regime, which affected the diel phases especially when lasting more than 5–6 h, could substantially influence the dynamics of water depletion and replenishment in single-leaf pinyon pine