1,491 research outputs found
Down in arms: Marine climate stress inhibits growth and calcification of regenerating \u3ci\u3eAsterias forbesi\u3c/i\u3e (Echinodermata: \u3ci\u3eAsteroidea\u3c/i\u3e) arms
Anthropogenic CO2 is changing the pCO2, temperature, and carbonate chemistry of seawater. These processes are termed ocean acidification (OA) and ocean warming. Previous studies suggest two opposing hypotheses for the way in which marine climate stress will influence echinoderm calcification, metabolic efficiency, and reproduction: either an additive or synergistic effect. Sea stars have a regenerative capacity, which may be particularly affected while rebuilding calcium carbonate arm structures, leading to changes in arm growth and calcification. In this study, Asterias forbesi were exposed to ocean water of either ambient, high temperature, high pCO2, or high temperature and high pCO2 for 60 days, and the regeneration length of the amputated arm was measured weekly. Ocean acidification conditions (pCO2 ~1180 μatm) had a negative impact on regenerated arm length, and an increase in temperature of +4°C above ambient conditions (Fall, Southern Gulf of Maine) had a positive effect on regenerated arm length, but the additive effects of these two factors resulted in smaller regenerated arms compared to ambient conditions. Sea stars regenerating under high pCO2 exhibited a lower proportion of calcified mass, which could be the result of a more energetically demanding calcification process associated with marine climate stress. These results indicate that A. forbesi calcification is sensitive to increasing pCO2, and that climate change will have an overall net negative effect on sea star arm regeneration. Such effects could translate into lower predation rates by a key consumer in the temperate rocky intertidal of North America
SDCS quantum mechanical flux formula revisited for electron-hydrogen ionization
Through a simple, classical, energy conservation analysis, we propose a fi-nite distance reinterpretation of the standard energy fraction definition used for the electron-hydrogen S wave ionization process. The energy modification is due to the fact that, at finite distances from the nucleus, the continuum electrons have to over-come the remaining potential energy to be completely free. As a consequence, the flux formula for extracting - at finite distances - single differential cross sections (SDCS) is also modified. Differently from the usual observations, the proposed corrections yield finite and well behaved SDCS values also at the asymmetrical situation where one of the continuum electrons carries all the energy while the other has zero energy. Re-sults of calculations performed at various impact energies, for both singlet and tripletsymmetry, are presented and compared favorably with benchmark theoretical data. Although we do not know how, we believe that finite distance effects should strongly affect the evaluation of the flux and consequently the SDCS, also in the full electron-hydrogen case.Fil: Ancarani, L. U.. Université de Lorraine; FranciaFil: Randazzo, Juan Martin. Comisión Nacional de Energía Atómica. Gerencia del Area Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Balseiro). División Colisiones Atómicas; Argentin
Tourist or Traveler? Unpacking Informal Conversations between Teachers and Young Children across Diversity
The world is in the midst of a dramatic demographic shift: culturally, ethnically, and socioeconomically. To address the needs of an increasingly diverse student population, research has examined the effects of teacher-student relationships. This chapter describes a study that used autophotography to examine the ways teachers engage in informal conversations with young children who come from different racial, ethnic, and socioeconomic backgrounds, around the child’s own photos of home. Specifically, conversations were interrogated to identify what impacts the teacher-student interactions across differences. Using Gee’s discourse analysis, this study explored how the teachers built or lessened what the children viewed as significant, how they distributed their social goods—influence, power, or status—and how they created or positioned identities within the conversations. The findings inform the mission of enhancing teacher-student relationships and content relevance through providing new insights into how teachers and young children interact, connect, and change within their conversations
Optical Module Front-End for a Neutrino Underwater Telescope: PMT interface
A proposal for a new system to capture signals in the Optical Module (OM) of an Underwater Neutrino Telescope is described. It concentrates on the problem of power consumption in relation to precision. In particular, a solution for the interface between the photomultiplier (PMT) and the front-end electronics is presented
Impiego di batteri lattici autoctoni per il miglioramento igienico-sanitario del Pecorino Siciliano DOP
Il Pecorino Siciliano DOP \ue8 considerato
il pi\uf9 antico formaggio prodotto in
Sicilia e, probabilmente, d\u2019Europa. Le
citazioni storiche sulla sua antica origine
risalgono al IX secolo a.C. in uno
dei passi pi\uf9 famosi dell\u2019odissea di Omero,
quando Ulisse incontra Polifemo. In seguito,
anche Aristotele e Plinio esaltano il gusto
unico di questo formaggio. In particolare,
proprio Plinio, nella sua opera \u201cNaturalis
Historia\u201d, redige una carta dei formaggi nella
quale vengono citati, tra i migliori pecorini,quelli provenienti da Agrigento.
Fra le caratteristiche peculiari del Pecorino
Siciliano DOP vanno annoverati il sapore
leggermente piccante e l\u2019incantevole profumo
di pascolo. Il Pecorino Siciliano DOP \ue8
un formaggio a pasta dura, semicotto, prodotto
con latte intero crudo di pecora. L\u2019areale
di produzione si estende su tutta la regione
Sicilia.
La forma \ue8 cilindrica a facce piane o lievemente
concave, pesa dai 4 ai 12 kg, lo scalzo
\ue8 di 10-18 cm. La crosta \ue8 bianca-giallognola,con la superficie rugosa per la modellatura
lasciata dal canestro in giunco dove avviene
la formatura, spesso viene cappata con
olio. La pasta \ue8 compatta, di colore bianco
o giallo paglierino, con occhiatura scarsa. Il
sapore \ue8 piccante e caratteristico, l\u2019aroma \ue8
intenso. La stagionatura minima prevista dal
disciplinare \ue8 di 4 mesi.
Il Pecorino Siciliano ha acquisito la certificazione
DO nel 1955 e la DOP nel 1996 con
regolamento CE n. 1107/96 della Commissione
del 12 giugno 1996 (Gazzetta Ufficiale
Comunit\ue0 Europea L 148 del 21/6/1996). Attualmente,
le attivit\ue0 di promozione, valorizzazione
e vigilanza sono affidate al Consorzio
di tutela del Pecorino Siciliano DOP,
che \ue8 stato riconosciuto dal ministero delle
Politiche agricole, alimentari e forestali (Mi-
Paaf) dal 2005 a oggi.
L\u2019elevata eterogeneit\ue0 del prodotto osservata
nelle forme presenti sul mercato \ue8 dovuta
sia ai metodi di produzione artigianali sia al
vecchissimo disciplinare di produzione, risalente
al 1956. Ci\uf2 ha indotto il consorzio
di tutela a intraprendere una proficua collaborazione
tecnico-scientifica con l\u2019Universit\ue0
degli Studi di Palermo prima e l\u2019Istituto
Zooprofilattico Sperimentale della Sicilia, il
Corfilac e l\u2019Universit\ue0 di Catania successivamente,
con l\u2019obiettivo di migliorare la qualit\ue0
igienico-sanitaria del formaggio Pecorino Siciliano
DOP e ridurre l\u2019eccessiva variabilit\ue0
qualitativa fra le forme ottenute da differenti
caseificazioni
THE MOSAIC OF THE FRIGIDARIUM OF “VILLA BONANNO” IN PALERMO: MINERALOGICAL AND PETROGRAPHIC ANALYSES FOR IN SITU CONSERVATION AND RESTORATION INTERVENTIONS
The topic of this study was the mineralogical and petrographic characterization of bedding mortars (made of different layers) and tesserae of Roman age (3rd century A.D.), taken from the mosaic of the Frigidarium of “Villa Bonanno”, brought to light by archaeological excavations conducted in the historical centre of Palermo. The collected samples have been analysed by thin-section optical microscopy (PLM), and scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS). The study was aimed to define the “recipe” (composition of aggregate and binder, aggregate size distribution, aggregate/binder ratio), in order to assess the provenance of raw materials (supply site/area) and to acquire useful information in order to formulate "restoration mortars" that should be most comparable with the original ones, for replacements and/or integration. Rock types constituting the coloured tesserae were also characterized by thin-section optical microscopy.
The mineralogical and petrographic investigations allowed establishing two different recipes used for the formulation of the studied mortars in terms of both compositional and textural features. The aggregate is composed by diverse proportions of detritic calcareous granules (both bioclasts and limestone fragments deriving from the local outcropping biocalcarenites and limestones), siliceous sand (monocrystalline quartz, chert and quartzarenite fragments), volcanic ash (pozzolana) and sometimes cocciopesto. The resulting hydraulic binder was the product of the „pozzolanic reaction‟ between volcanic ash and the aerial lime (specifically made by the calcination of locally available magnesian limestone or dolostone). The coloured tesserae can be all classified as compact limestones of Mesozoic or Cenozoic age, likely of local provenance
Smart Analogue Sampler for the Optical Module of a Cherenkov Neutrino Detector
A transient waveform sampler/recorder IC has been developed and realized in AMS C35B4 technology. This chip has been designed to fit the needs of a proposal for a front-end architecture for the readout of the anode signal of the photomultipliers in an underwater neutrino telescope. The design is based around a 3 channels x 32 cells switched capacitor array unit sampling its voltage inputs at 200MHz external clock rate and transferring the stored analogue voltage samples to its single analogue output at 1/10th of the sampling rate. This unit is replicated inside the ASIC providing 4 independent analogue sampling queues for signal transients up to 32 x 5 ns and a fifth unit storing transients up to 128 x 5 ns. A micro-pipelined unit, based on Muller C-gates, controls the 5 independent samplers. This paper briefly summarizes the complete front-end architecture and discusses in more detail the internal structure of the ASIC and its first functional tests
Characterization of Cell-Envelope Proteinases from Two Lacticaseibacillus casei Strains Isolated from Parmigiano Reggiano Cheese
Microbial Consortia Involved in Traditional Sicilian Sourdough: Characterization of Lactic Acid Bacteria and Yeast Populations
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