8,973 research outputs found
Spettroscopia computazionale di materiali disomogenei secondo la teoria delle perturbazioni di molti corpi: sviluppo di metodi e applicazioni.
No full textNel quadro dell'approssimazione GW, l'interazione schermata W è un potenziale non locale e dinamico che può avere una struttura complessa nella sua dipendenza dalla frequenza. Una descrizione completa di tale dipendenza in un ampio intervallo di energia è in molti casi proibitiva: per questo motivo, è pratica comune approssimarla utilizzando un modello di polo plasmonico (PP). L'approccio PP può tuttavia fallire per sistemi disomogenei, come interfacce e difetti, e anche per alcuni materiali sfusi, inclusi ad es. metalli.
In questo lavoro esploro un approccio multipolare per ottenere una rappresentazione efficace di W. Dimostro che strategie di campionamento ottimali nel piano complesso possono portare a precisioni confrontabili con metodi a piena frequenza a costi molto inferiori e discuto l'applicazione di tali strategie ai sistemi prototipo pertinenti.
Infine, mostrerò la rilevanza dello sviluppo proposto nel caso di un sistema ibrido molecola-grafene-metallo. Le proprietà strutturali, elettroniche e magnetiche di un insieme di questi tipi di interfacce vengono studiate a livello DFT, prima di applicare le approssimazioni della teoria delle perturbazioni di molti corpi.In the framework of the GW approximation, the screened interaction W is a non-local and dynamical potential that may have a complex structure in its frequency dependence. A full description of such dependence in a large energy range is in many cases prohibitive: for this reason, it is common practice to approximate it using a plasmon pole (PP) model. The PP approach may however fail for inhomogeneous systems, such as interfaces and defects, and also for some bulk materials, including e.g. metals.
In this work I explore a multi-pole approach for getting an effective representation of W. I show that optimal sampling strategies in the complex plane can lead to accuracies comparable with full-frequency methods at much lower costs, and discuss the application of such strategies to relevant prototype systems.
Finally, I will show the relevance of the proposed development in the case of a hybrid molecule-graphene-metal system. The structural, electronic and magnetic properties of a set of these kinds of interfaces are studied at the DFT level, before applying many body perturbation theory approximations
El valido del virrey. Poder, 'patronage' y clientelismo en la corte virreinal mexicana (1612-1635)
No full textBüschges C. El valido del virrey. Poder, 'patronage' y clientelismo en la corte virreinal mexicana (1612-1635). In: América Latina: Outro Ocidente? Actas do XII Congresso Internacional de la Associaçao de Historiadores Latinoamericanistas Europeus (Porto, 21 a 25 de setembro de 1999). Porto; 2001: 141-150
Taphonomy on the beach: experimental approach to bone modifications made by insects on an island (Gran Canaria, Canary Island, Spain)
No full textInsects play a crucial role in cadaveric decomposition, yet their contribution to taphonomic alterations on bones is often overlooked. This study investigates insect activity's impact on bone surface modifications under different environmental conditions. Five unfleshed pig heads were subjected to varied settings-buried and exposed-across coastal and inland contexts. Nine insect taxa were identified, including flies (Sarcophagidae, Calliphoridae [Chrysomia albiceps], Fanniidae, Muscidae), beetles (Dermestidae [Dermestes maculatus], Cleridae [Necrobia rufipes], Hydrophilidae [Cercyon cf. arenarius]), ants (Formicidae [Tetramorium depressum]), and termites (Kalotermitidae [Cryptotermes brevis]). Taphonomic changes observed on bone surfaces varied between buried and exposed specimens, with greater insect diversity and more pronounced modifications in exposed samples. Striations, linear marks, perforations, and bone destruction were linked to specific insect taxa, revealing novel osteophagic behavior in certain species. Termite activity, identified by faecal pellets, occasionally resulted in bone damage. Notably, beetle-induced alterations were absent in coastal environments, suggesting post-decomposition transport when these modifications appear on bone elements from coastal sites. This is the first experimental study in archaeoentomology, providing critical insights into insect-driven taphonomic processes in coastal and inland archaeological sites, with implications for forensic and archaeological interpretations of bone alterations.150,9712,2Q1Q1AHCISCIESSCI10,6ERIH PLU
Arqueoentomología y arqueobotánica de los espacios de almacenamiento a largo plazo: el granero de Risco Pintado, Temisas (Gran Canaria)
No full textThis contribution aims at understanding the storage techniques used in the past by means of studying the entomological and plant remains present in the pre-hispanic granary of Risco Pintado, dated between the IX and XV centuries cal AD.This type of granary groups together a large number of silos excavated in the volcanic tuff, situated on steep escarpments, difficult to access and easy to defend.The exceptional environmental conditions of these infrastructures have allowed the desiccated remains of the stored plant products and the pests associated with such storage to be preserved within the silos.The domestic species documented include cereals (barley and wheat), legumes (broad beans and lentils) and fruits (figs), as well as other gathered indigenous plants.Together with these remains, insects that developed as primary and secondary storage pests are recorded (grain weevil and sawtoothed grain beetle).To combat these infestations, the ancient Canarians used a number of natural insecticides (laurel and lentisk).The presence of these pests is analysed as an indicator of long-term storage and of the strategies developed to ensure the integrity of stored plant resources.Este trabajo pretende contribuir al estudio de las técnicas de almacenamiento utilizadas en el pasado mediante el análisis de los restos entomológicos y vegetales presentes en el granero prehispánico canario de Risco Pintado, fechado entre los siglos IX y XV cal DC. Este tipo de granero se caracteriza por agrupar numerosos silos excavados en la toba volcánica y situarse en lugares escarpados de difícil acceso y fácil defensa. Las excepcionales condiciones ambientales de estas infraestructuras han permitido la conservación en el interior de los silos de restos desecados de los productos vegetales almacenados y de las plagas asociadas al ensilado. Las especies domésticas documentadas incluyen cereales (cebada y trigo), legumbres (habas y lentejas) y frutales cosechados (higos), así como otros vegetales silvestres recolectados. Junto a estos restos se registran insectos que se desarrollan como plagas primarias y secundarias del almacenamiento (gorgojos del grano y dientes de sierra). Estas plagas se combatieron mediante insecticidas naturales como el laurel y el lentisco. Se analiza la presencia de estas plagas como un indicador de almacenamiento a largo plazo y de las estrategias desarrolladas para asegurar la integridad de los recursos vegetales almacenados
O valido em cena. Política, história e crítica social em ¿Cómo ha de ser el privado?, de Francisco de Quevedo
No full textThe valido was a polemic personage during the 17th century in the ambit of the political culture on the Ancien Regime. This article aims to provide an analysis of how valido was treated within the genre of dramaturgy called Comedia de la Privanza, in keeping with Francisco de Quevedo’s comedy ¿Cómo ha de ser el privado?, which poses relevant questions about the phenomenon of valimento, as well as Quevedo’s controversial relationship with the Count-Duke of Olivares’ regime, valido of Felipe IV.El valido fue un polémico personaje en el siglo XVII en el ámbito de la cultura política del Antiguo Régimen. Este texto busca ofrecer un análisis acerca de cómo el valido fue tratado en el género de la dramaturgia llamada Comedia de la Privanza, ateniéndose a la comedia ¿Cómo ha de ser el privado?, de Francisco de Quevedo, por el relieve que presenta acerca del fenómeno del valimiento, así como de la controvertida relación de Quevedo con el régimen del Duque de Olivares, valido de Felipe IV.O valido foi uma personagem polêmica durante o século XVII no âmbito da cultura política do Antigo Regime. Este artigo pretende oferecer uma análise de como o valido foi tratado dentro do gênero de dramaturgia denominado Comedia de la Privanza, atendo-se à comédia ¿Cómo ha de ser el privado?, de Francisco de Quevedo, que coloca questões relevantes acerca do fenômeno do valimento, bem como da controversa relação de Quevedo com o regime do conde-duque de Olivares, valido de Felipe IV
Reseña de: Valladares, Rafael (ed.), El mundo de un valido. Don Luis de Haro y su entorno, 1643-1661, Madrid, Marcial Pons, 2016
No full textReseña de: Valladares, Rafael (ed.), El mundo de un valido. Don Luis de Haro y su entorno, 1643-1661, Madrid, Marcial Pons, 2016, 456 pp., isbn: 9788415963943.</jats:p
La tyrannie du valido dans la pensée politique espagnole au temps de Lerma et d’Olivarès
No full textInternational audiencePlan : - Une réactivation des discours du XVe siècle contre la privanza ?- Usages du lexique de la tyrannie au sujet du privado ou du valido au XVIIe siècle- Des intentions diverses et des aspirations différentes pour la monarchie- Conclusion
El valido «encubierto»: Don Luis de Haro y Calderón
No full textEl valido reapareció en España con el duque de Lerma y Felipe III a finales del siglo XVI. A partir de ese momento se escribieron obras de teatro en las que este personaje se convirtió en protagonista. Lo interesante es que no solo encontramos validos en las comedias y dramas, sino también en autos sacramentales. En El lirio y el azucena, representado en 1660, Calderón retrata a don Luis de Haro, primer ministro de Felipe IV, que jugó un papel importante en las conversaciones de paz entre España y Francia y en la boda de María Teresa de Austria y Luis XIV. El análisis del auto sacramental demuestra que, según Calderón, don Luis de Haro fue el último valido o primer ministro de Felipe IV.The favourite reappeared in Spanish politics at the end of the 16th century with the duke of Lerma and Philip III. From that moment, works were published presenting that minister as main character. Interestingly, these these characters cannot only be found in comedies or dramas but in sacramental plays as well. El lirio y el azucena by Pedro Calderón, performed in 1660, portrays don Luis de Haro, primeminister of Philip IV, who played an important role in the peace talks between Spain and France, and in the marriage of María Teresa de Austria and Luis XIV. The analysis of the sacramental play proves that, according to Calderón, don Luis de Haro was the last favourite or prime minister of Philip IV
Lopo Fernandes Pacheco: um valido de D. Afonso IV
No full textO túmulo de Lopo Fernandes Pacheco encontra-se abundantemente estudado por vários autores. No entanto , pouco se sabe sobre esta personagem que ocupou uma posição de grande destaque na corte do rei D. Afonso IV (1325-1357). Não descurando os estudos já realizados ao seu túmulo , este trabalho procura traçar o percurso deste valido régio demonstrando que a imponência do seu monumento funerário , localizado na capela de S. Cosme e S. Damião na Charola da Sé de Lisboa, poderá ser uma consequência da importância deste senhor que foi, talvez, a mais importante personagem do reinado de D. Afonso IV.Palavras-chave: nobreza, Portugal, século XIV, Lopo Fernandes Pacheco. Linhagem, corte, património
A 40.9 mu W high sensitivity wake-up radio for wireless sensor networks using uncertain-IF architecture
No full textThis paper presents an 868 MHz wake-up radio using uncertain-IF architecture for wireless sensor network. It is designed to receive data modulated with on-off-keying in UMC 65nm CMOS technology and it employs uncertain-IF architecture to reduce the oscillator design constraints and to decrease power consumption. The wake-up radio consist of a single-ended active mixer, a five stage IF-amplifier and a differential envelope detector biased in weak inversion. The wake-up radio has been designed with to provide a trade-off between sensitivity and power consumption. The obtained sensitivity and power consumption is -78 dBm and 40.9 μW, respectively, with 1.2 V power supply.
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