Constraining Emission Models of Luminous Blazar Sources

Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy (gamma-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of gamma-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and gamma-ray frequencies. We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intra-day flares occasionally observed in powerful blazars sources.Comment: 34 pages, accepted for publication in the Astrophysical Journa

Drought surveillance in Sri Lanka.

Case study related to Sri Lanka. IWMI developed the South Asia Drought Monitoring System (SADMS) which was further improved by devising the Soil Water Anomaly Drought Index (SWADI) in order to forecast drought impacts on agriculture on a regular basis. Together with other tools, SADMS is able to support contingency planning at national and regional levels. The knowledge products are regularly shared with the Disaster Management Centre, to mitigate drought risks and addressing improved food security

Science, Art and Geometrical Imagination

From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental role of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Durer, Kepler, Escher, Grisey or the present author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as beauty, conciseness and emotional approach of the world.Comment: 22 pages, 28 figures, invited talk at the IAU Symposium 260 "The Role of Astronomy in Society and Culture", UNESCO, 19-23 January 2009, Paris, Proceedings to be publishe

The use of satellite products to assess spatial uncertainty and reduce life-time costs of offshore wind farms

Managers of offshore wind farms make strategic decisions based on information about site wind speeds and significant wave heights (SWH) available from numerical weather predictions (NWP) or local in-situ measurements. However, the coarse resolution with which such information are available, both in space and time, introduces a high degree of uncertainty into the decision process which in turn may result in higher costs during different stages of offshore wind farm life. The current work investigates how space-borne data describing wind speeds and SWH might be used to quantify spatial uncertainties and support decisions during the design and operation of offshore wind sites. Results have revealed that due to high spatial variance of wind speed, the estimated wind power can differ from that provided by an offshore met mast up to 11%. The methodology proposed for SWH has shown how data collected from distinct satellites can be efficiently interpolated (maximum absolute error observed around 1 m) to generate high-resolute spatial information of sea water surface, regardless of satellite trajectory distributions. The work has provided insights on how the propagation of measurement uncertainty through the wind farm area can affect both management costs and wind energy production over the plant life-cycle

(In)finite extent of stationary perfect fluids in Newtonian theory

For stationary, barotropic fluids in Newtonian gravity we give simple criteria on the equation of state and the "law of motion" which guarantee finite or infinite extent of the fluid region (providing a priori estimates for the corresponding stationary Newton-Euler system). Under more restrictive conditions, we can also exclude the presence of "hollow" configurations. Our main result, which does not assume axial symmetry, uses the virial theorem as the key ingredient and generalises a known result in the static case. In the axially symmetric case stronger results are obtained and examples are discussed.Comment: Corrections according to the version accepted by Ann. Henri Poincar

Including albedo in time-dependent LCA of bioenergy

Albedo change during feedstock production can substantially alter the life cycle climate impact of bioenergy. Life cycle assessment (LCA) studies have compared the effects of albedo and greenhouse gases (GHGs) based on global warming potential (GWP). However, using GWP leads to unequal weighting of climate forcers that act on different timescales. In this study, albedo was included in the time-dependent LCA, which accounts for the timing of emissions and their impacts. We employed field-measured albedo and life cycle emissions data along with time-dependent models of radiative transfer, biogenic carbon fluxes and nitrous oxide emissions from soil. Climate impacts were expressed as global mean surface temperature change over time ( increment T) and as GWP. The bioenergy system analysed was heat and power production from short-rotation willow grown on former fallow land in Sweden. We found a net cooling effect in terms of increment T per hectare (-3.8 x 10(-11) K in year 100) and GWP(100) per MJ fuel (-12.2 g CO(2)e), as a result of soil carbon sequestration via high inputs of carbon from willow roots and litter. Albedo was higher under willow than fallow, contributing to the cooling effect and accounting for 34% of GWP(100), 36% of increment T in year 50 and 6% of increment T in year 100. Albedo dominated the short-term temperature response (10-20 years) but became, in relative terms, less important over time, owing to accumulation of soil carbon under sustained production and the longer perturbation lifetime of GHGs. The timing of impacts was explicit with increment T, which improves the relevance of LCA results to climate targets. Our method can be used to quantify the first-order radiative effect of albedo change on the global climate and relate it to the climate impact of GHG emissions in LCA of bioenergy, alternative energy sources or land uses

The worsening impacts of land reclamation assessed with Sentinel-1: The Rize (Turkey) test case

Massive amounts of land are being reclaimed to build airports, new cities, ports, and highways. Hundreds of kilometers are added each year, as coastlines are extended further out to the sea. In this paper, this urbanization approach is monitored by Persistent Scatterer Interferometry (PSI) technique with Sentinel-1 SAR data. The study aims to explore this technology in order to support local authorities to detect and evaluate subtle terrain displacements. For this purpose, a large 3-years Sentinel-1 stack composed by 92 images acquired between 07/01/2015 to 27/01/2018 is employed and stacking techniques are chosen to assess ground motion. The test site of this study, Rize, Turkey, has been declared at high risk of collapse and radical solutions such as the relocation of the entire city in another area are been taken into consideration. A media fact-checking approach, i.e. evaluating national and international press releases on the test site, is considered for the paper and this work presents many findings in different areas of the city. For instance, alerts are confirmed by inspecting several buildings reported by the press. Critical infrastructures are monitored as well. Portions of the harbor show high displacement rates, up to 1 cm/year, proving reported warnings. Rural villages belonging to the same municipality are also investigated and a mountainous village affected by landslide is considered in the study. Sentinel-1 is demonstrated to be a suitable system to detect and monitor small changes or buildings and infrastructures for these scenarios. These changes may be highly indicative of imminent damage which can lead to the loss of the structural integrity and subsequent failure of the structure in the long-term. In Rize, only a few known motion-critical structures are monitored daily with in-situ technologies. SAR interferometry can assist to save expensive inspection and monitoring services, especially in highly critical cases such as the one studied in this paper

Louis Charles Karpinski, historian of mathematics and cartography

Louis C. Karpinski was best known for his publications on the history of mathematics, and secondarily as a historian of cartography. This survey of his life includes an account of his contributions to the teaching of mathematics and of his avocational interests as a collector, chess player, and gadfly attacking what he saw as poor thinking and abuses of power in both the universities and in the public domain. It is followed by a note on archives, a list of the Ph.D. theses he supervised, and a complete bibliography.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21777/1/0000171.pd

THE EFFECT OF ACUTE MAXIMAL AEROBIC EXERCISE ON BLOOD LIPID PARAMETERS ON HEALTHY MALES AND FEMALES

Abstract Purpose : The aim of the present study was to examine the effect of acute maximal aerobic exercise on blood lipid parameters on healthy males and females. Methods : The heights, weights, resting hearth rates and blood samples of subjects were taken before the exercise. The subjects warmed up for ten minutes before they had 20 m shuttle run test protocole until exhaustion. The blood samples were taken before and immediately after the exercise for analizing triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol. Statistical evaluation was conducted using SPSS 13 software program. The Wilcoxon Signed Rank Test was used for determine the differences within groups and Mann-Whitney U Test was used for beetwen groups results at a significance levels of p<0.05 and p<0.01. Results : In conclusion, our study demonstrates that acute aerobic exercise has benefical effects on the blood lipid profile