172,644 research outputs found
Anelli e monete. Cronologia, tipologie, fruitori
No full textFra le diverse classi della gioielleria monetale antica, gli anelli sembrano aver goduto di un successo che attraversa le diverse epoche, senza soluzione di continuità. Tale tipologia di monili,inoltre, riveste un particolare interesse per la complessa rete semantica demandata agli anelli toutcourt, grazie alla loro funzione sigillaria, di simbolo di patto nuziale, di emblema di status sociale.
Il saggio analizza innanzitutto i tre anelli aurei ritrovati nella sepoltura contenuta nel grande tumulo di
Ryzhanivka, presso Kiev (270 a.C. circa), che incastonano stateri d'oro della zecca di Panicapeo (330 e il 304 a. C.). Essi rappresentano i soli antecedenti noti degli anelli monetali di produzione romana. I 22 monili oggi consosciutivsono esaminati dapprima negli aspetti cronotipologici. Viene poi affrontata la questione relativa ai fruitori di tale classe della gioielleria monetale, attingendo a fonti letterarie e ai pochi dati di contesto pervenuti.The paper studies the chronology, typologies and users of Roman coin rings
Canone novecentesco e manuali scolastici: un'indagine
No full textIl saggio presenta i risultati di un’indagine di tipo frequenziale condotta sui repertori antologici della letteratura italiana del XX secolo in un campione costituito da venti manuali scolastici per il triennio superiore attualmente disponibili sul mercato. Anche attraverso la comparazione con i sondaggi effettuati alla metà degli anni Novanta dal collettivo Zippo (1995, 1996), esso intende così restituire dalla prospettiva dell’insegnamento secondario un quadro aggiornato dei valori canonici del Novecento letterario
Design and fabrication of mid-infrared devices for IoT applications
No full textThe advancement of photonics has transformed the fields of communication and sensing, allowing for outstanding improvements in transmission speed, accuracy, miniaturization, and scalability. This Ph.D. thesis reports the design and fabrication of Mid-InfraRed (Mid-IR) devices tailored for Internet of Things (IoT) applications, focusing on the use of optical fibers based on soft glasses. The research encompasses various optical components, including Bragg gratings inscribed on flat fibers and planar substrates, and optical fiber devices based on stretching and heating fabrication technique such as combiners, couplers, photonic lanterns, long period gratings (LPGs), non-adiabatic tapers, and S-tapers. Additionally, the modelling and design of a Praseodymium-doped laser is explored to enhance Mid-IR light generation.
The initial section of this thesis concentrates on the design, fabrication, and characterization of innovative Bragg gratings. These are wavelength-selective mirrors, essential for the construction of laser cavities. Moreover, they can be used as sensors exploiting the Bragg wavelength shift to measure various physical parameters, such as strain, curvature, and temperature. These results were achieved in collaboration with the University of Southampton (Optoelectronic Research Centre - ORC, UK) and the University of Bristol (School of Civil, Aerospace and Design Engineering, UK).
Considering the increasing interest in the Mid-IR spectral range, the second part of the thesis investigates the design, fabrication, and characterization of Mid-IR optical fiber components based on soft glasses, mainly operating within the wavelength range from λ=0.5 μm to λ=5.5 μm. Optical fiber combiners and couplers are key building blocks in communication and sensing systems, serving for spectral splitting/combining and the increasing of optical power. Photonic lanterns offer an efficient interface between multi-mode and single-mode waveguides, proving beneficial in astrophotonics where “every photon counts”. LPGs and tapers enable sensing capabilities in the Mid-IR, spectral range that allows to identify the typical bonds of many molecules. In collaboration with Le Verre Fluoré (Bruz, France), the development of a specialized manufacturing process for soft glasses permitted the fabrication and characterization of these devices.
Finally, Bragg gratings in combination with some of the developed building blocks allow the fabrication of all-in-fiber Mid-IR amplifiers, and lasers systems. In this context, optical fiber lasers, emitting in the Mid-IR wavelengths, can be employed for novel communication and sensing schemes. Therefore, the design and optimization of a Mid-IR continuous wave (CW) laser based on Praseodymium, is reported in the last part of the Ph.D. research work.
Some of the findings from this research have been published in International Journals and presented at National and International Conferences, as detailed in the list at the end of the thesis
The basilica of the eastern harbor of Hephaestia (Lemnos). Preliminary research report in 2019|La basilica del porto orientale di efestia (Lemno). Relazione preliminare delle ricerche del 2019
No full textThe IASA archaeological expedition continued to investigate the basilica complex located on the Eastern harbor of Hephaestia, Lemnos. Investigations resumed in 2018, ninety-two years after the discovery of the site. During the 2019 excavation season, the structures of the Early Byzantine basilica were completely brought to light, as well as an associated room located north of the narthex. The stratigraphic excavations of the central nave of the Early Byzantine basilica revealed the overlying single nave of the Middle Byzantine church, cruciform in plan. Moreover, excavations below the apse revealed two structures that date to the Archaic-Classic and Hellenistic phases of occupation of this site. This paper presents the preliminary results of the 2019 excavation season and the related study of the finds. © 2019, Scuola Archeologica Italiana di Atene. All rights reserved
The basilica of the eastern harbor of Hephaestia (Lemnos). Preliminary research report in 2019|La basilica del porto orientale di efestia (Lemno). Relazione preliminare delle ricerche del 2019
No full textLa basilica del porto orientale di Efestia (Lemno). Relazione preliminare delle ricerche 2019
No full textLa missione archeologica della SAIA a Lemno ha proseguito le indagini presso la basilica del porto orientale di Efestia, riprese nel 2018 a novantadue anni dalla scoperta. Sono state messe in luce per intero le strutture della fase proto-bizantina ed è stato individuato un ambiente annesso a N del nartece. Lo scavo stratigrafico della navata centrale ha consentito di rintracciare le strutture di una navata singola, pertinente alla chiesa cruciforme, realizzata in età medio-bizantina sulle spoglie della basilica. Nell'area dell'abside, alcuni sondaggi in profondità hanno permesso di individuare due strutture relative alle fasi di occupazione dell'area portuale in età arcaico-classica ed ellenistica. Si presentano in questa sede i risultati preliminari della campagna di scavo e di studio dei materiali del 2019.The IASA archaeological expedition continued to investigate the basilica complex located on the Eastern harbour of Hephaestia, Lemnos. Investigations resumed in 2018, ninety-two years after the discovery of the site. During the 2019 excavation season, the structures of the Early Byzantine basilica were completely brought to light, as well as an associated room located north of the narthex. The stratigraphic excavations of the central nave of the Early Byzantine basilica revealed the overlying single nave of the Middle Byzantine church, cruciform in plan. Moreover, excavations below the apse revealed two structures that date to the Archaic-Classic and Hellenistic phases of occupation of this site. This paper presents the preliminary results of the 2019 excavation season and the related study of the finds
Chemical analysis of tree rings to trace the effects of volcanic eruptions
No full textopenL’obiettivo della seguente tesi è quello di individuare una possibile connessione tra eruzioni vulcaniche e composizione chimica degli anelli di accrescimento dei ginepri. Si vuole verificare se sia possibile datare eruzioni vulcaniche in base ad arricchimenti di elementi chimici in anelli compresi circa fra l’anno 1000 e il 1600. Per rispondere alla domanda, è stato necessario analizzare la concentrazione nelle piante prese in esame di elementi minori (quindi escludendo C, O, H) che fossero elementi nutritivi, quindi assorbiti dal terreno, o al contrario elementi dannosi per queste ultime rilasciati tipicamente a seguito di eruzioni (es. zinco, zolfo...). Una volta eseguita questa distinzione, sono stati esaminati i picchi ottenuti dai vari elementi e successivamente datati servendosi dell’analisi dendrocronologica.
Ciò si è reso possibile in quanto attraverso lo studio degli anelli è possibile risalire a eventi accaduti secoli/millenni fa, ricostruendo la storia dell’albero e le condizioni ambientali presenti prima delle eruzioni. Dunque si può affermare che gli anelli fungono da registratori di eventi climatici.The aim of the following thesis is to identify a possible connection between volcanic eruptions and the chemical composition of juniper’s growth rings. It is intended to verify whether it is possible to date volcanic eruptions on the bases of chemical elements enrichments between approximately the year 1000 and 1600. To answer the question, it was necessary to analyze the concentration in the plants examined of minor elements (therefore excluding C, O, H) that were nutritive elements, therefore absorbed from the soil, or on the contrary harmful elements to the latter typically released as a result of eruptions (e.g. zinc, sulfur...). Once this distinction was made, the peaks obtained from the various elements were examined and subsequently dated using dendrochronological analysis.
This was possible because through the study of the rings it is possible to trace events that occurred centuries/milleniums of years ago, reconstructing the history of the tree and the environmental conditions present before the eruptions. So it can be said that the growth rings act as recorders of climatic events
Is the placenta an innocent bystander in perinatal programming?
No full textDuring pregnancy, a well functioning placenta is needed to ensure appropriate growth and development of the fetus [1]. Indeed, a malfunctioning or “insufficient” placenta has been recognized as the “cause” of Intrauterine Growth Restriction (IUGR) [2], leading to decreased oxygen delivery as well as altered placental transport of nutrients, mainly amino acids and lipids, but also micronutrients such as iron and folate. A number of previous studies from our lab support this hypothesis, demonstrating a specific placental phenotype of IUGR [3], recently confirmed with decreased levels of placental Transferrin Receptor (TFRC – mediating cellular iron uptake) or of Sodium-coupled Neutral Amino acid transporter 2 (SNAT2) in IUGR versus controls [4, 5] (summarized in Tab. 1). Maternal nutritional status, diet and exposure to environmental factors are increasingly acknowledged as potentially affecting placental gene expression, thus modifying placental function. These epigenetic associations link intrauterine environment to adverse perinatal outcomes reprogramming the fetal epigenome with several mechanisms, such as methylation or miRNA, thus affecting gene expression and activity in preeclamptic (PE) and IUGR tissues [6]. Changes in miRNA expression pattern have been observed in placental tissue and associated with several pregnancy pathologies as preeclampsia (DOWN miR-21, UP miR-155, DOWN miR-223), GDM (DOWN miR-132), IUGR (DOWN miR-21, DOWN miR-210) and preterm birth (UP miR-493, UP miR-338) [7]. In this context, an active placental metabolism is crucial to support both trophoblast invasion and placentation [8]. Alterations in early implantation may lead to mismatches in oxygen (O2) delivery to different areas of the placenta, with less O2 exchange between the uterine and the umbilical circulations [9]. Mitochondrial DNA (mtDNA) copy number is positively correlated with the number of mitochondria. We have previously demonstrated altered mitochondrial content in IUGR placentas [10], with higher mtDNA levels in IUGR maternal blood [11]. Moreover, we measured the functionality of the respiratory complexes (RCC) by high-resolution respirometry (HRR), in order to assess potential alterations in placental energy metabolism [12] (summarized in Tab. 1). Preliminary observations suggest similar changes in placental mitochondria, DNA content and function of obese pregnant women. These pregnancies are characterized by low-grade inflammation and oxidative stress [13]. Moreover, dysregulated mt genes methylation (D-loop and CO1 hypomethylation) might expand our findings of higher mtDNA content in fetal cord blood of
IUGR and PE [14]. These preliminary data may indeed suggest a compensatory attempt of fetuses to increase energy production through higher mtDNA content and RCC (CO1) expression, representing a further link between epigenetic
changes and perinatal programming of diseases. Another issue is related to the placental hormonal function. The placenta as a source of a wide array of hypothalamic or pituitary hormones was a hot topic in the 60-70s, then neglected because of the radioactive techniques needed at that time. Steroid hormones, and in particular estrogens, are important for uterine/placental vascular adaptations to pregnancy, but also essential for trophoblast cells syncytialization in placenta. During pregnancy, the feto-placental unit is a source of estrogens through its aromatase enzyme Cytochrome P450 (CYP19) involved in estradiol (E2) production [15]. Interestingly, CYP19 levels appeared signi%cantly higher in IUGR placentas that we recently analyzed. We might speculate that the CYP19 alterations have an estrogenrelated protective action in more severe IUGR placentas, which we showed to be characterized by increased mtDNA [16]. Ongoing analyses will evaluate if these placental molecular alterations result in E2 hormone altered production. Placental mesenchymal stromal cells (p-MSCs) may also represent an interesting point to evaluate in order to understand normal and abnormal placental development. In IUGR pregnancies, p-MSCs have lower proliferation rate with earlier shift towards homogeneity than in controls. In vitro findings also demonstrate that multipotency of IUGR derived p-MSCs is restricted, as their capacity for adipocyte differentiation is increased, whereas their differentiation ability towards endothelial cell lineage is decreased (Fig. 1) [17]. These findings are indicative of changes that may also be reflected in the developing fetus (summarized in Tab. 1).
The potential role for p-MSCs in pregnancy pathologies, as well as the striking mitochondrial changes involved in energy production, open new perspectives for understanding the development of the diseases and potential routes of prevention and treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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