305,563 research outputs found
A functional limit theorem for stochastic integrals driven by a time-changed symmetric sigma-stable Levy process
No full textUnder proper scaling and distributional assumptions, we prove the convergence in the Skorokhod space endowed with the -topology of a sequence of stochastic integrals of a deterministic function driven by a time-changed symmetric Œ±-stable Lévy process. The time change is given by the inverse Œ≤-stable subordinator
On the convergence of quadratic variation for compound fractional poisson processes
No full textThe relationship between quadratic variation for compound renewal processes and M-Wright functions is discussed. The convergence of quadratic variation is investigated both as a random variable (for given t) and as a stochastic process. © 2012 Diogenes Co., Sofia
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
Elsie Viles, 80, of Augusta, is donating a 6,200-square-foot modern home, comple
No full textElsie Viles, 80, of Augusta, is donating a 6,200-square-foot modern home, complete with two swimming pools, a tennis court and nine acres of land, to the state for use as a judicial office and conference center. The property is next to Viles\u27 85-acre property on the east side of Augusta. Maine Supreme Judicial Court Chief Justice Daniel E. Wathen, a friend of Viles, announced the planned gift, and will benefit by getting office space in the building
Ecosustainable and phytobased alternative methods for the conservation of biodeteriorated stone materials
No full textIl presente lavoro di tesi propone di sviluppare un metodo finalizzato al trattamento di materiali lapidei biocolonizzati, tramite l’impiego di sostanze chimiche di origine naturale (i.e. fitochimici), caratterizzati da un basso impatto ambientale, una bassa tossicità per l’uomo e che non compromettano lo stato conservativo dei beni culturali.
In questa prospettiva, sono state sfruttate le già note proprietà biocide di tre Oli Essenziali (EOs) già largamente studiati e impiegati in diversi ambiti, tra cui quello della conservazione dei beni culturali. Tali sostanze sono ottenute a partire da piante molto comuni della flora mediterranea, ed in particolare si tratta degli oli di Origanum vulgare, Thymus vulgaris e Clinopodium nepeta. Ogni olio essenziale ha una composizione chimica molto eterogenea, sebbene siano sempre presenti uno o due componenti chimici maggioritari, anche definiti Principi Attivi (APs), che ne definiscono il chemiotipo e sembrerebbero condizionarne l’azione biocida, sebbene non sia ancora stato sistematicamente dimostrato. In virtù di quanto detto, l’effetto biocida dei tre oli essenziali è stato confrontato con quello dei loro rispettivi principi attivi ovvero: carvacrolo per O. vulgare, timolo per T. vulgaris e pulegone per C. nepeta.
Per valutarne un possibile incremento dell’azione biocida, ogni olio è stato applicato singolarmente e in combinazione con gli altri due, in modo da creare diverse miscele contenenti rispettivamente, uno, due e tre composti, e lo stesso è stato fatto per i principi attivi. L’applicazione sulle superfici lapidee biocolonizzate ha previsto l’incapsulamento delle sostanze attive all’interno di una matrice idrogel (HG) di nuova formulazione, composta dalla miscela di sostanze polimeriche e tensioattivi, i cui più grandi vantaggi sono legati all’atossicità nella composizione chimica e alla capacità di formare un film omogeneo, pelabile, facile da rimuovere dalle superfici una volta asciutto. I composti sono stati testati su diversi biofilm presenti su substrati lapidei in granito e travertino. In particolare, le sperimentazioni hanno previsto l’applicazione su campioni di granito (in laboratorio) e su due superfici murarie, una in granito e una in travertino, esposte a diverse condizioni ambientali. Per la valutazione dell’azione biocida e pulente dei composti fitochimici, sono state effettuate misure non invasive di colore e di fluorescenza che potranno essere replicate anche sui beni culturali. Il sistema ottenuto dalla combinazione dell’idrogel e dei fitochimici (phyto-HG) ha mostrato buoni risultati per quanto riguarda l’azione pulente e biocida nei confronti di differenti biofilm, anche rispetto a quelle dimostrate da un sistema classicamente utilizzato per la pulitura meccanica dei beni culturali (spazzolatura) e di un comune biocida (Preventol® RI80).
Le prove sperimentali hanno messo in evidenza l’efficacia dei principi attivi i quali, possono essere considerati, nella maggior parte dei casi, più efficienti rispetto ai corrispondenti oli essenziali. Questo risultato è molto incoraggiante per le future sperimentazioni riguardanti lo sviluppo del metodo, che potrebbe prevedere l’impiego dei soli principi attivi per la realizzazione delle formulazioni biocide, con i notevoli vantaggi legati ai minori costi di produzione e alla possibilità di ridurre i limiti legati all’impossibilità di controllare le composizioni chimiche degli estratti naturali.
L’azione ottenuta dalla combinazione di più sostanze necessita ulteriori approfondimenti, in quanto sembrerebbe che la loro azione sia condizionata dalla sinergia che si ottiene da più sostanze nei confronti di specifici microorganismi presenti.
Il monitoraggio a medio e a breve termine effettuato sui campioni sperimentali ha evidenziato un’azione prolungata delle sostanze nel tempo. Sebbene questo non possa essere considerato sempre vantaggioso, in quanto ci si potrebbero aspettare delle reazioni secondarie che potrebbero verificarsi tra i residui e la matrice lapidea, è importante comunque sottolineare i vantaggi legati all’inibizione a lungo termine nei confronti di una possibile ricolonizzazione della superficie. Per queste ragioni, risulta importante analizzare più approfonditamente la stabilità dei fitochimici nel tempo, tramite l’osservazione di possibili modifiche delle proprietà chimiche ed estetiche dei materiali.The present PhD thesis aims to develop a valid strategy for the treatment of the biocolonization of stone materials, by employing natural chemical substances (i.e. phytochemicals) harmless towards ecosystems, human health, and cultural heritage materials. To achieve this goal, the well know biological properties of the Essential Oils (EOs) have been exploited, by employing three of these plant extracts that have already demonstrated inhibitory effects towards different microorganisms. These oils are obtained from Mediterranean plants of the Lamiaceae family, in particular: Origanum vulgare, Thymus vulgaris and Clinopodium nepeta. Each EO is characterized by the presence of one or two mayor chemical components, also defined Active Principles (APs). It seems that the biocidal action of each EO is established by the presence of specific APs, although this was not systematically proven. To demonstrate what has just been said, in this study, the effect of the EOs has been compared to the one of the respective APs, which are carvacrol for O. vulgare, thymol for T. vulgaris and pulegone for C. nepeta. Each EO has been applied alone and combined with the two others, in mixtures containing two and three EOs. The same process occurred with the APs. This was done to assess a possible empowerment of the biocidal action when more substances are combined. For their application on biodegraded stone surfaces, the phytochemicals were incorporated inside an innovative hydrogel (HG) matrix based on a mixture of polymeric substances and surfactants; whose main advantage is linked to its ability of forming a peelable layer when applied on surfaces. The compounds were tested on biofilms, colonizing granite and travertine surfaces. The experimentations were performed on granite samples and on two biocolonized walls, one in granite and the other in travertine. The biocidal and cleaning properties of the systems composed by the phytochemical substances and the hydrogel have been assessed through non-invasive colorimetric and fluorescence measurements. The phyto-HG systems demonstrated good cleaning and large spectrum biocidal properties against different biofilms, also compared to the ones of a commonly employed mechanical cleaning tool (brushing) and a common biocide (Preventol ® RI80).
The APs also showed their broad-spectrum biocidal action, which can be considered, in many cases, higher than the one of the respective EOs. This is an encouraging result, in sight of possible future developments of the method, that will provide the employment of the only APs for the creation of the formulations, with notable advantages linked to the reduction of the production costs and the possibility of reducing the limits linked to the impossibility of controlling the chemical composition of the natural extracts (i.e. the EOs).
The action of the combined substances compared to biofilms needs to be further analysed, because it seems that their action is strongly linked to the synergism occurring between two substances and the specific microorganisms present.
The short-term and medium-term monitoring carried out on the experimental samples evidenced a prolonged action of the substances in time. Even though this is not always encouraged, since possible secondary reactions may occur between the chemical residuals and the mineralogical matrix, it is important to stress the advantage related to the long-term inhibition towards a secondary biological growth on the surfaces. For these reasons, it will be important to further analyse the stability of the substances in time, by observing possible modifications in the properties of the stones during the time
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
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