Silver as a constraint for a large-scale development of solar photovoltaics? Scenario-making to the year 2050 supported by expert engagement and global sensitivity analysis

In this study we assess whether availability of silver could constrain a large-scale deployment of solar photovoltaics (PV). While silver-paste use in photovoltaics cell metallization is becoming more efficient, solar photovoltaics power capacity installation is growing at an exponential pace. Along photovoltaics, silver is also employed in an array of industrial and non-industrial applications. The trends of these uses are examined up to the year 2050. The technical coefficients for the expansion in photovoltaics power capacity and contraction in silver paste use have been assessed through an expert-consultation process. The trend of use in the non-PV sectors has been estimated through an ARIMA (auto-regressive integrated moving average) model. The yearly and cumulative silver demand are evaluated against the technological potential for increasing silver mining and the estimates of its global natural availability, respectively. The model implemented is tested with a quasi-random Monte Carlo variance-based global sensitivity analysis. The result of our inquiry is that silver may not represent a constraint for a very-large-scale deployment of photovoltaics (up to tens TW in installed power capacity) provided the present decreasing trend in the use of silver paste in the photovoltaics sector continues at an adequate pace. Silver use in non-photovoltaic sectors plays also a tangible influence on potential constraints. In terms of natural constraints, most of the uncertainty is dependent on the actual estimates of silver natural budget

Graduate Student Recital: Sandra P. Thompson, Trombone; Donna Stadsholt, Piano; June 30, 197

Centennial East Recital HallSunday AfternoonJune 30, 19745:15 p.m

Normative Values for Near and Distance Clinical Tests of Stereoacuity.

PurposeExtensive literature exists on normative stereoacuity values for younger children, but there is less information about normative stereoacuity in older children/adults. Individual stereotests cannot be used interchangeably-knowing the upper limit of normality for each test is important. This report details normative stereoacuity values for 5 near/distance stereotests drawn from a large sample of participants aged 16-40 years, across 3 studies.MethodsParticipants (n=206, mean age 22.18±5.31 years) were administered the following stereotests: TNO, Preschool Randot, Frisby, Distance Randot, and Frisby-Davis 2. Medians and upper limits were calculated for each test.ResultsUpper limits for each stereotest were as follows: TNO (n=127, upper limit=120" arc), Preschool Randot (PSR, n=206, upper limit=70" arc), Frisby (n=206, upper limit=40" arc), Distance Randot (n=127, upper limit=160" arc), and Frisby-Davis 2 (n=109, upper limit=25" arc).ConclusionsNormative values for each stereotest are identified and discussed with respect to other studies. Potential sources of variation between tests, within testing distances, are also discussed

Surface morphology and magnetic anisotropy in (Ga,Mn)As

Atomic Force Microscopy and Grazing incidence X-ray diffraction measurements have revealed the presence of ripples aligned along the $[1\bar{1}0]$ direction on the surface of (Ga,Mn)As layers grown on GaAs(001) substrates and buffer layers, with periodicity of about 50 nm in all samples that have been studied. These samples show the strong symmetry breaking uniaxial magnetic anisotropy normally observed in such materials. We observe a clear correlation between the amplitude of the surface ripples and the strength of the uniaxial magnetic anisotropy component suggesting that these ripples might be the source of such anisotropy.Comment: 3 pages, 4 figures, 1 table. Replaced with published versio

Beta-diversity and stressor specific index reveal patterns of macroinvertebrate community response to sediment flushing

Anthropogenic increase of fine sediment loading is one of the main pressures for rivers worldwide. Particularly, Alpine streams are increasingly facing this issue due to sediment flushing operations from hydropower reservoirs, aimed at recovering storage for preserving electricity generation. Although Controlled Sediment Flushing Operations (CSFOs) are becoming increasingly frequent, ecological indicators to adequately assess and monitor their impact on the stream ecosystem have been poorly developed. In this work, we aimed to perform a screening of currently available biomonitoring tools to evaluate the CSFO effects on the riverine biota and adequately assess its recovery, starting from the recognition of the main ecological mechanisms triggered by the mentioned activities on benthic macroinvertebrate communities. We used two independent datasets concerning two reservoirs in the central Italian Alps to investigate the temporal effects of CSFOs repeated for four consecutive years (case-study I), and the impact of a single CSFO at a seasonal scale through a before/after-control/impact approach (case-study II). Initially, we quantified the CSFO impact on the richness and beta-diversity of macroinvertebrate communities by combining multivariate and univariate statistical techniques. Then, we compared the performance of the Siltation Index for LoTic EcoSystems (SILTES), recently developed for detecting siltation impact in Alpine streams, with that of the generic index currently adopted to assess the ecological status (sensu Water Framework Directive) of the Italian rivers, and of another sediment-specific index, but developed for a different bio-geographical area. The analysis of the two case-studies demonstrated that the nestedness (i.e. taxa loss) is the primary source of biological impairment caused by CSFOs. Moreover, we found that SILTES was more effective than the other indices because of its strong correlation with the nestedness, and since it properly discriminated impaired and pristine conditions, at both multi-annual and seasonal scale. In the first case-study, a threshold in the temporal trend of this index was detected, indicating a recovery within three months. In the second one, SILTES showed a recovery to pre-event seasonal values after nine months from the CSFO, due to larger and more persistent sediment deposition. This study demonstrates that SILTES could be adopted as a benchmark to improve the management of CSFOs from an ecological viewpoint. Our findings can be extended to the management of other sediment-related activities affecting mountainous streams worldwide, and, more generally, the adopted approach can be replicated for developing new ecological tools to manage other disturbances to river environments

SURVEY ON V. CHOLERAE, V. VULNIFICUS AND V. PARAHAEMOLYTICUS IN BIVALVE MOLLUSCS OF THE ADRIATIC SEA AND PROPOSAL OF AN ANALYTICAL PROTOCOL

Bivalve molluscs from Adriatic sea were analyzed for V. parahaemolyticus, V. cholerae e V. vulnificus presence. The isolates on TCBS Agar and m-CPC Agar were selected on the basis of a new biochemical screening, that showed a good performance, because among 2344 strains from primary culture only 237 (10%) were presumptively assigned to the species of interest. The PCR analyses was performed for the target genes toxR hlyA, ctxA, tcpI (V. cholerae), toxR, tl, tdh, trh (V. parahaemolyticus), vvhA and viuB (V. vulnificus). Among the 9 strains confirmed to belong to V. parahaemolyticus specie, 6 were sucrose positive. On 215 samples of molluscs only 5 resulted positive for V. parahaemolyticus being toxR+, tl+, although non pathogenic (tdh-, trh-), and none for V. cholerae e V. vulnificus

CFD-based methodology for the characterization of the combustion process of a passive pre-chamber gasoline engine

Pre-chamber (PC) ignition systems, enabling Turbulent Jet Ignition (TJI) combustion, represent a promising technology to extend the lean limit of Spark Ignition Internal Combustion Engines. Indeed, the higher ignition energy provided by the turbulent jets contributes to the limitation of combustion duration and variability even in diluted conditions. However, a detailed analysis of the combustion process is needed to maximize the performance of the system. More specifically, the interaction between the chemical and the turbulent scales are key factors in assessing the probabilities of main chamber (MC) ignition, determining the ignition pattern, and characterizing the combustion process. For this reason, the development of reliable numerical models is a crucial factor to pave the way toward a deeper understanding of details concerning TJI combustion. In the present work, a 3D-CFD numerical model was validated against experimental data at 4000 rpm, in stoichiometric and lean (i.e., λ = 1.2) conditions in a single-cylinder gasoline engine equipped with a passive pre-chamber. In both operations, the evolution of the turbulent combustion regimes over the whole combustion process was investigated, highlighting analogies and differences between the selected operative conditions. Additionally, a methodology to characterize the MC ignition and combustion process, able to describe the different phases of the interaction between PC and MC, and assess the thermal, turbulent, and chemical effects of the turbulent jets is presented

Il contenimento del consumo di suolo a scala europea: il Programma ESPON

La pianificazione e lo sviluppo territoriale hanno informato l’agenda europea negli ultimi 10 anni soprattutto attraverso l’European Spatial Planning and Development Perspective (ESDP) formalizzatosi attraverso gli studi dell’European Spatial Planning Observatory Network (ESPON) e le Guidelines for the Sustainable Development of the European Continent del Council of Ministers of the Wider Europe with responsibility for Regional Planning (CEMAT)). Pur inizialmente lontani da quella concezione pienamente territoriale propria del pensiero geografico ed urbanistico italiano, che si è manifestata solo nel 2007, questi contributi rappresentano un forte incentivo a rinnovare l’atteggiamento politico, economico, culturale nei confronti del valore che il territorio, la sua utilizzazione e la sua identità hanno per lo sviluppo. Di fronte a queste sollecitazioni, nell’ultimo quinquennio il Programma ESPON si è aperto alla revisione dei paradigmi e dei contenuti operativi disciplinari, affrontando e sviluppando temi quali: i cambiamenti strutturali e le grandi tendenze del territorio europeo tra il 1998 e il 2007 (la coesione, sostenibilità e il cambiamento climatico, il policentrismo, l’urbano-rurale, la dimensione competitiva delle città anche medio-piccole, la governance, il cambiamento demografico, ecc.); l’integrazione tra i principi della ricerca geoeconomica e della pianificazione attraverso la creazione di modelli multidisciplinari applicabili a differenti scale - NUTs 2, 3, 4 - per l’individuazione delle capacità competitive endogene entro i limiti di sostenibilità; le procedure e gli strumenti di valutazione comuni per la scelta di politiche e piani/programmi in applicazione delle direttive europee (Territorial Impact Assessment – TIA); lo sviluppo di GIS e database dedicati alla conoscenza e alla gestione di processi cooperativi comparabili trasparenti, sussidiari, integrati; la definizione e l’applicazione di un protocollo di indicatori statistico-economico-geografici condivisi e certificati a sostegno dei processi decisionali; lo sviluppo di case study transnazionali sui temi principali della politica UE. In Italia, molti di questi cambiamenti sono stati introdotti e sperimentati attraverso i progetti speciali, tematici, strategici ESPON, confermando il valore di nuovi orientamenti geografici e della pianificazione, che coinvolgono direttamente i policy makers. I risultati dei progetti di ricerca transnazionale ESPON promossi tra il 2000-2006 e il 2007-2010 , ed in particolare quelli più legati alla dimensione territoriale ed urbana delle strategie europee in applicazione della Territorial Agenda 2007, hanno consentito di misurare e sperimentare anche in Italia indicatori, metodi, criteri di ricerca comuni, rivelatisi utili alla discussione internazionale e nazionale che accompagnano la revisione di molti temi, tra cui l’uso del suolo, la città e il suo rapporto con con l’area vasta di più stretta pertinenza, la provincia come luogo centrale della sussidiarietà europea (Prezioso, 2009)

Gamma-ray observations of Cygnus X-1 above 100 MeV in the hard and soft states

We present the results of multi-year gamma-ray observations by the AGILE satellite of the black hole binary system Cygnus X-1. In a previous investigation we focused on gamma-ray observations of Cygnus X-1 in the hard state during the period mid-2007/2009. Here we present the results of the gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 carried out for which includes a remarkably prolonged `soft state' phase (June 2010 -- May 2011). Previous 1--10 MeV observations of Cyg X-1 in this state hinted at a possible existence of a non-thermal particle component with substantial modifications of the Comptonized emission from the inner accretion disk. Our AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1, provide a significant upper limit for gamma-ray emission above 100 MeV of F_soft < 20 x 10^{-8} ph/cm^2/s, excluding the existence of prominent non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We discuss theoretical implications of our findings in the context of high-energy emission models of black hole accretion. We also discuss possible gamma-ray flares detected by AGILE. In addition to a previously reported episode observed by AGILE in October 2009 during the hard state, we report a weak but important candidate for enhanced emission which occurred at the end of June 2010 (2010-06-30 10:00 - 2010-07-02 10:00 UT) exactly in coincidence with a hard-to-soft state transition and before an anomalous radio flare. An appendix summarizes all previous high-energy observations and possible detections of Cygnus X-1 above 1 MeV.Comment: 16 pages, 12 figures, 1 table, accepted for publication in Ap