Composite mirror facets for ground based gamma ray astronomy

Composite mirrors for gamma-ray astronomy have been developed to fulfill the specifications required for the next generation of Cherenkov telescopes represented by CTA (Cherenkov Telescope Array). In addition to the basic requirements on focus and reflection efficiency, the mirrors have to be stiff, lightweight, durable and cost efficient. In this paper, the technology developed to produce such mirrors is described, as well as some tests that have been performed to validate them. It is shown that these mirrors comply with the needs of CTA, making them good candidates for use on a significant part of the array.Comment: 16 pages, 13 figures, accepted to be published on NIM

Genetic variability of host-parasite relationship traits: utilization of isofemale lines in a Drosophila simulans parasitic wasp

International audienc

Francis Johnson: Music Master of Early Philadelphia

Guthrie P. Ramsey, Jr., Associate Professor of Music, University of Pennsylvania, delivers a lecture on Francis Johnson (1792-1844), Philadelphia band leader and composer. Johnson holds a special place in the history of American music. Although a free African American, he lived in an age when racial segregation and prejudice were commonplace. Despite these obstacles, he was able to achieve extraordinary renown and respect among the elite of Philadelphia through performances of his band at balls, parades, and promenade concerts. Following a series of concert tours late in his life, Johnson\u27s fame eventually extended through the Midwest and across the Atlantic to London. His music survives today in piano arrangements published during his lifetime. The lecture marked the opening of an exhibition in the Otto E. Albrecht Music Library. The exhibition included a selection from the over forty pieces of Johnson sheet music in the collection of the late Kurt Stein. Also part of the exhibition were prints, period newspaper articles, and a Kent bugle like that favored by Johnson. To download a podcast of the lecture, select one of the additional files below. Welcome, H. Carton Rogers, 00-04:52 Introduction, Richard Griscom, 04:52-13:06 Lecture, Guthrie P. Ramsay, Jr., 13:15-37:27 The event announcement is also available for download, by selecting the download button, at upper right. The exhibition is available in an online version, at: https://web.archive.org/web/20160422121347/https://www.library.upenn.edu/exhibits/music/fjohnson

Aspects of slurry management on pig farms.

End of Project ReportThe objectives of manure or slurry management on intensive pig farms are the provision of adequate slurry storage capacity and the efficient recycling of the slurry nutrients for crop production. However, recent surveys of pig slurry dry matter suggest there is excessive dilution of raw pig slurry with water. This has two important implications for management. The first is greater storage capacity will be required due to the increased volume of slurry generated. Slurry storage is expensive. For example, a 350 sow unit adding 10 weeks storage needs to invest £50,000. Secondly, evidence from the literature indicates an improved slurry nitrogen efficiency with the more dilute manure. The results of field trials showed that higher dry matter pig slurries reduced the relative efficiency of pig slurry nitrogen for second cut silage production. This is probably linked to reduced ammonia volatilisation losses, consequent to the less viscous nature of dilute slurry which permits a more rapid infiltration of the ammonium nitrogen into the soil. The use of a band spreader or shallow injection rather than the conventional splash plate were shown to increase the efficiency of pig slurry nitrogen for grass silage production. Therefore, the potential for the higher pig slurry dry matter, required for cost effective storage/ handling costs, to reduce the efficiency of its nitrogen for grass silage production can be partially offset by using band spreaders or shallow injection spreading systems. These have the added advantage of reducing odour emissions from the land spreading operation.Teagasc Walsh Fellowship Programm

Interaction between a surface quasi-geostrophic buoyancy anomaly jet and internal vortices

This paper addresses the dynamical coupling of the ocean's surface and the ocean's interior. In particular, we investigate the dynamics of an oceanic surface jet, and its interaction with vortices at depth. The jet is induced by buoyancy (density) anomalies at the surface. We first focus on the jet alone. The linear stability indicates there are two modes of instability: the sinuous and the varicose modes. When a vortex in present below the jet, it interacts with it. The velocity field induced by the vortex perturbs the jet and triggers its destabilisation. The jet also influences the vortex by pushing it under a region of co-operative shear. Strong jets may also partially shear out the vortex. We also investigate the interaction between a surface jet and a vortex dipole in the interior. Again, strong jets may partially shear out the vortex structure. The jet also modifies the trajectory of the dipole. Dipoles travelling towards the jet at shallow incidence angles may be reflected by the jet. Vortices travelling at moderate incidence angles normally cross below the jet. This is related to the displacement of the two vortices of the dipole by the shear induced by the jet. Intense jets may also destabilise early and form streets of billows. These billows can pair with the vortices and separate the dipole.PostprintPeer reviewe

RAPPRESENTAZIONE IN CARTA DELLE CARATTERISTICHE DEI SENTIERI AI FINI DELLA MITIGAZIONE DEL RISCHIO GEOMORFOLOGICO

L’ambiente naturale di alcuni particolari ambiti geografici è in rapida evoluzione non solo per quanto riguarda le sue variabili, legate alle tendenze climatiche in atto, ma anche in relazione all’aumentata frequentazione turistica. La maggiore diffusione dei mezzi di risalita in montagna e di navigazione lungo le coste, rende possibile l’accesso anche a siti altrimenti difficilmente raggiungibili: ciò porta ad un contatto rapido e diretto con ambienti talvolta mutevoli in tempi brevi. La crescente richiesta di una maggiore conoscenza dell’ambiente naturale, che si esplica per lo più attraverso la frequentazione della rete sentieristica, implica la necessità di abbinare alle proposte di percorsi ed itinerari, note illustrative e carte tematiche di immediata lettura, che evidenzino sia i siti di interesse naturalistico - culturale sia le possibili situazioni di rischio e di difficoltà di percorrenza degli itinerari stessi. Esistono infatti alcuni elementi morfologici del territorio che di per sé non costituiscono una pericolosità in senso stretto ma che, a seconda delle capacità del fruitore, possono essere fonte indiretta di danno, in quanto rendono difficile l’attraversamento di alcuni punti specifici o la percorrenza di particolari tratti di sentiero. Contemporaneamente la stagionalità in alcune regioni climatiche e la variabilità meteorologica possono incrementare sia la pericolosità sia la vulnerabilità e di conseguenza il rischio per il frequentatore. Obiettivo del presente lavoro è quello di proporre una simbologia adeguata da inserire sulle carte dei sentieri, e più specificatamente su quelle geoturistiche, per una rapida e facile identificazione di specifiche situazioni riscontrabili lungo itinerari: questi simboli, che dovranno riferirsi solo alla percorribilità dell’itinerario e non alla valorizzazione naturalistica dello stesso, andranno rappresentati su base topografica separata, al fine di non appesantire la lettura dell’elaborato cartografico principale e dovranno fornire solo informazioni oggettive che saranno poi interpretate dal fruitore dell’itinerario. La simbologia e le note terranno conto sia delle caratteristiche costanti dei sentieri che degli elementi variabili, in funzione anche delle condizioni climatiche o stagionali, a seconda dei diversi ambienti interessati

Multiple causes of interannual sea surface temperature variability in the equatorial Atlantic Ocean

The eastern equatorial Atlantic Ocean is subject to interannual fluctuations of sea surface temperatures, with climatic impacts on the surrounding continents. The dynamic mechanism underlying Atlantic temperature variability is thought to be similar to that of the El Nino/Southern Oscillation (ENSO) in the equatorial Pacific, where air-sea coupling leads to a positive feedback between surface winds in the western basin, sea surface temperature in the eastern basin, and equatorial oceanic heat content. Here we use a suite of observational data, climate reanalysis products, and general circulation model simulations to reassess the factors driving the interannual variability. We show that some of the warm events can not be explained by previously identified equatorial wind stress forcing and ENSO-like dynamics. Instead, these events are driven by a mechanism in which surface wind forcing just north of the equator induces warm ocean temperature anomalies that are subsequently advected toward the equator. We find the surface wind patterns are associated with long-lived subtropical sea surface temperature anomalies and suggest they therefore reflect a link between equatorial and subtropical Atlantic variability

Nitrogen Response of Spring and Winter Wheat to Biosolids Compared to Chemical Fertiliser

Irish sewage sludge production was over 30,000 t/year in the 1990s (EPA, Ireland, 2003). Application to agricultural land is a management option for this organic material as it results in the recycling of the nutrients they contain for crop production. The EU Directive (91/271/EEC) encourages the recycling of sewage sludge as biosolids to agriculture. However, up to 1999, only about 5 % of biosolids produced was applied to agricultural land. In this study, several biosolids and a chemical fertiliser were used to assess N availability for spring and winter wheat (Triticum aestivum,) production in a pot experiment