Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

Wastewater treatment and reuse: Past, present, and future

10.3390/w7094887Water (Switzerland)794887-489

The effect of water stress and rootstock on the development of leaf injuries in grapevines irrigated with saline effluent

Deficit irrigation is increasingly being practiced in water-limited areas to overcome water scarcities. Although, this practice reduces yield losses, there is limited information currently available on how this practice can affect crops when the irrigation water contains elevated levels of salts. An experiment was set up to investigate salt uptake and distribution and salt tolerance of potted Soultanina vines grafted on different rootstocks (41B, 1103P, 110R) and irrigated with effluent containing relatively high concentrations of salts and fresh water at different fractions of evapotranspiration (0.50, 0.75 and 1.00ET). Irrigation with recycled water induced the development of leaf burns, which were more intense in 1998 despite the lower leaf-Na and -Cl content. This may have been due to the more severe water deficit and/or to the more adverse climatic conditions which prevailed during that season. Decreasing the irrigation level induced the development of leaf burns causing only minor changes to leaf-Na or -Cl content. Differences in salt uptake, accumulation and distribution were observed among the rootstocks investigated in this work, suggesting that differences exist in the mechanisms regulating salt uptake and distribution in the shoot. Despite these differences, a distinct superiority in terms of salinity tolerance among rootstocks was only observed at the 0.50ET irrigation level, where vines grafted on 41B developed earlier and more acute leaf burns than the other rootstocks. These findings suggest that leaf salt content alone it is not to classify genotypes according to their tolerance to salinity and that salinity-induced damage is linked with prevailing environmental conditions. Furthermore, it can be inferred that grapevines have additional mechanisms to cope with salt stress which may counteract differences in salt uptake and accumulation in the shoot.

Water scarcity management: Part 1: Methodological framework

Water scarcity and water availability puts significant constraints in the social and economic development of many regions and countries around the world, especially the arid and semi-arid regions, as well as deteriorates the quality of life. The current problem of water scarcity consists of the adverse result of ineffective water resource management and policies, as well as the availability of water in these regions. This paper presents a methodological overview of a sustainable water resource management framework through technical and scientific analyses of water scarcity management in regions vulnerable to drought and water scarcity. The methodological framework consists of procedures, including database development, climate variability and modelling, water quantity and quality modelling, a summary of hierarchical drought analysis, water demands assessment. In case of significant reduction in water availability, the analyses are expected to explore alternative water resource solutions, such as non-conventional measures related to marginal waters, including rain enhancement, desalination, water treatment and reuse potential, water harvesting, trends and practices under drought and water scarcity conditions. Once the water demands are assessed, a water resource management scheme is implemented, along with an economic model to evaluate the economic feasibility of the management scenarios. Copyright © 2018 Inderscience Enterprises Ltd

Groundwater utilization through the centuries focusing οn the Hellenic civilizations [Utilisation de l’eau souterraine à travers les siècles se focalisant sur les civilisations grecques] [Αξιοποίηση των υπόγειων νερών διαμέσου των αιώνων με έμφαση στους Ελληνικούς πολιτισμούς] [L’utilizzo durante i secoli delle acque sotterranee nella civiltà ellenica] [تفاده از آب های زیرزمینی در قرون متمادی با در نظر گرفتن تمدن های یونان] [Utilização das águas subterrâneas através dos séculos com foco nas civilizações helênicas] [Utilización del agua subterránea a través de los siglos enfocando sobre las civilizaciones helénicas]

Groundwater has been utilized since the Prehistoric times. Water supply of some Minoan settlements on the eastern side of the island of Crete (Greece) was based on groundwater. Later on, many wells were constructed in several areas of Greece and their use expanded through subsequent periods. The greatest achievement in groundwater exploitation by ancient Greeks was the construction of long underground galleries or qanats, which collected water from springs and alluvial deposits. In Classical times, most of the wells were on private properties and their owners were forced by regulations to maintain the wells in good condition and ready for use in wartime. During that period, the first scientific theories of Aristotle and Theophrastus were developed in regards to hydrological phenomena, and the processes involved in the formation of surface water and groundwater were clarified. Wells played a major part in urban water supply during the Roman period, in which famous aqueducts were constructed to transfer water; however, several regions of Greece were self-sufficient in water, supplied by many wells from the Prehistoric to the Byzantine period. People understood the local geological conditions and, according to their culture, constructed and managed their own types of wells. In addition to the wells and aqueducts, the hydraulic technology included cisterns to store rainwater, and systems to capture spring water for transport by aqueducts. The examples of hydro-technologies and water management practices described in this paper may have some relevance for water engineering even in modern times. © 2016, Springer-Verlag Berlin Heidelberg

Water reuse in EU states: Necessity for uniform criteria to mitigate human and environmental risks

10.1080/10643389.2014.955629Critical Reviews in Environmental Science and Technology45131409-146