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Particle transport in gravel‐bed rivers: Revisiting passive tracer data
No full textData from tracer experiments were compiled and analysed in order to explore the role of geomorphological, hydrological and sedimentological constraints on fluvial gravel transport in gravel‐bed rivers. A large data set from 217 transport episodes of tagged stones were compiled from 33 scientific papers. Our analyses showed that while magnitude of peak discharge is a major control on gravel transport and mobility, tracer travel distances show some scale dependence on the morphological configuration of the channel. Our results also highlight differences in the way tracers are displaced between step–pool and riffle and pool channels. The riffle–pool sequence seems to be a more efficient trap for travelling gravels than the step–pool pair. In addition, in step–pool channels there are clear differences in tracer transport between observations of first displacements after tracer seeding (unconstrained‐stone conditions), and second and subsequent observations of tracer displacements (constrained‐stone conditions). The comparison between tracer experiments under constrained conditions and those under unconstrained conditions also highlights the importance of bed state and structures in gravel mobility. The results of this study confirm that sediment transport in gravel‐bed rivers is a complex process, whereby sedimentological and geomorphological controls are superimposed on the hydraulic forcing.Ayudas postdoctorales ACA14‐30 y ACB17‐44, cofinanciadas por el programa ‘Clarin’ - FICYT (Principado de Asturias) / Marie Curie Cofund
In-Plane Anisotropic and Ultra-Low Loss Polaritons in a Natural van der Waals Crystal
No full textPolaritons—hybrid light–matter excitations—enable nanoscale control of light. Particularly large polariton field confinement and long lifetimes can be found in graphene and materials consisting of two-dimensional layers bound by weak van der Waals forces1,2 (vdW materials). These polaritons can be tuned by electric fields3,4 or by material thickness5, leading to applications including nanolasers6, tunable infrared and terahertz detectors7, and molecular sensors8. Polaritons with anisotropic propagation along the surface of vdW materials have been predicted, caused by in-plane anisotropic structural and electronic properties9. In such materials, elliptic and hyperbolic in-plane polariton dispersion can be expected (for example, plasmon polaritons in black phosphorus9), the latter leading to an enhanced density of optical states and ray-like directional propagation along the surface. However, observation of anisotropic polariton propagation in natural materials has so far remained elusive. Here we report anisotropic polariton propagation along the surface of α-MoO3, a natural vdW material. By infrared nano-imaging and nano-spectroscopy of semiconducting α-MoO3 flakes and disks, we visualize and verify phonon polaritons with elliptic and hyperbolic in-plane dispersion, and with wavelengths (up to 60 times smaller than the corresponding photon wavelengths) comparable to those of graphene plasmon polaritons and boron nitride phonon polaritons3,4,5. From signal oscillations in real-space images we measure polariton amplitude lifetimes of 8 picoseconds, which is more than ten times larger than that of graphene plasmon polaritons at room temperature10. They are also a factor of about four larger than the best values so far reported for phonon polaritons in isotopically engineered boron nitride11 and for graphene plasmon polaritons at low temperatures12. In-plane anisotropic and ultra-low-loss polaritons in vdW materials could enable directional and strong light–matter interactions, nanoscale directional energy transfer and integrated flat optics in applications ranging from bio-sensing to quantum nanophotonics
Parto de nalgas. Hospital Universitario Central De Asturias
No full textProtocolo del Servicio de Obstetricia y Ginecología el HUCA. Área Sanitaria I
An AC–DC PFC Single-Stage Dual Inductor Current-Fed Push–Pull for HB-LED Lighting Applications
No full textAn ac-dc single-stage driver for high-brightness light-emitting diodes (HB-LEDs) with galvanic isolation is presented in this paper. The driver is based on a dual inductor current-fed push-pull converter with each inductor operating in boundary conduction mode (BCM). The interleaving between the two inductors enables the converter to reduce the high input current ripple inherent to a BCM. Moreover, it is fully compliant with IEC 1000-3-2 Class C and it is able to achieve a high power factor (PF). Its low component count, simplicity, and overall outstanding characteristics make this current-fed topology suitable for medium power range HB-LED drivers in low-cost applications. The proposed topology has been tested on a 100-W prototype for the full range of the US single-phase line voltage, feeding several HB-LED strings, with an output voltage equivalent to 48 V at full load. The prototype achieves a maximum efficiency of 92% with a 0.99 PF, 8% total harmonic distorsion at full load while guaranteeing a good quality light.This work was supported in part by the Spanish Government under Project MINECO-13-DPI2013-47176-C2-2-R, in part by the Principality of Asturias under Severo Ochoa Grant BP14-142, Grant BP14-085, and Project FC-15-GRUPIN14-143, and in part by the European Regional Development Fund grants
Il canino mandibolare con doppia radice come indicatore di parentela nei cimiteri antichi. Il caso studio della necropoli altomedievale di Montichiari, Monte San Zeno (BS)
Get PDFITALIANO: Sei individui della necropoli altomedievale di Montichiari – Monte San Zeno (Brescia), datata tra VI e VII secolo, sono caratterizzati da un canino mandibolare con doppia radice. Tale tratto dentario è diffuso quasi esclusivamente nelle popolazioni europee, e si ritiene
avere una forte componente genetica. I sei individui esaminati risultano collocati lungo una medesima fila di tombe all’interno del cimitero, il che suggerisce un legame genetico tra di essi. I tratti dentari rari, come il canino mandibolare con doppia radice, in particolare se
intrecciati con i dati archeologici, costituiscono un utile strumento per l’individuazione dei gruppi parentali all’interno di una necropoli antica. / ENGLISH: Six individuals from the early medieval necropolis of Montichiari – Monte San Zeno, Brescia (6th-7th century AD), show a double-rooted lower canine, a rare non-metric trait that is more common in Europeans than in any other regional grouping. Several studies have reported that morphological dental traits are under strong genetic control. The six individuals examined are all placed along the same line of burials, suggesting a close blood relationship between them. Rare dental non-metric traits, such two-rooted lower canines, when used jointly with archaeological data, can be useful in intra-cemetery analysis, particularly in the identification of relatives within skeletal series
Juridical formulas in papal decretals of the twelfth and thirteenth centuries
Get PDFA significant number of Pope Alexander III’s decretal letters were incorporated into the "Liber Extra" becoming part of a cohesive juridical work that would remain as the principal source of Canon Law well into the Twentieth Century. If his direct association with the School of Bologna and Master Gratian is disputed (Noonan, 1977), the presence of juridical elements in his writings is undeniable. In face of the discussions surrounding Alexander III’s background, the present text analyzes the use of juridical formulas and terms in some of the pope’s decretals as well as his references to works of canon law, particularly to Gratian’s Decretum
Rappresentare il giudizio: il Processus Satane (XIV secolo) fra teologia e diritto
Get PDFITALIANO: Il Processus Satane è inserito con il titolo di Tractatus questionis ventilate coram domino nostro
Iesu Christo inter virginem Mariam ex una parte et diabolum ex altera parte nel corpus dei trattati di Bartolo da Sassoferrato. Si tratta di un processo assai singolare, svoltosi in Paradiso, fra il Diavolo e la Vergine Maria che disputano sul possesso del genere umano, davanti a Cristo giudice. Destinato alle scuole di diritto e a quelle di teologia, il testo costituisce una efficace “messa in scena” di questioni strettamente giuridiche e di problematiche filosofiche: dalla rappresentanza processuale delle donne alle tematiche legate al possesso e allo spolium, dalla teoria della Salvezza al problema dell’esistenza stessa del male e del “diritto” del diavolo sull’umanità. / ENGLISH:
With the title Tractatus questionis ventilate coram domino nostro Iesu Christo inter virginem Mariam ex una parte et diabolum ex altera parte, the Processus Satane is inserted into the corpus of the treaties of Bartolo of Sassoferrato. The trial took place in heaven, with Christ as judge,
between the Devil and the Virgin Mary who were disputing the possession of human beings. Addressed to both law and theology schools, the text is an effective “staging” of strictly legal and philosophical issues: from the legal representation of women, to possession and spolium, from
the theory of Salvation to the problem of the existence of evil and the Devil’s rights to humanity
L'espansione del principato longobardo di Salerno, nell'età di Guaimario III e Guaimario IV
Get PDFITALIANO: L’età di Guaimario III e di suo figlio, Guaimario IV, rappresentò il periodo di massimo sviluppo economico e politico del principato longobardo di Salerno. In quell’epoca, infatti, la compagine salernitana raggiunse la massima espansione territoriale, rinverdendo i “fasti” dell’indiviso principato di Arechi II. Nello stesso tempo, i principi salernitani stabilirono importanti relazioni diplomatiche col papato e con gli imperatori germanici. Un periodo di splendore che, tuttavia, durò meno di un secolo, a causa dell’avvento della conquista normanna. / ENGLISH: The age of Guaimario III and his son, Guaimario IV, was the most important moment for the economic and political development of the Salerno lombardic principality. In fact, in that age, the principality reached the greatest territorial expansion and restored the glorious deeds of the Benevento’s principality at the age of Arechi II. At the same time, the princes of Salerno established very important diplomatic relationships with the papacy and teutonic emperors. An age of magnificence that, however, lasted less than a century, in consequence of the Norman Conquest
I porti romani nel Mar Rosso da Augusto al Tardoantico
Get PDFITALIANO: Il volume punta a inserirsi nel contesto generale degli studi sul commercio che collegava l’antica Roma con i Paesi dell’Oriente, quali Arabia, Etiopia e India. Tale commercio è descritto dalle fonti antiche che riferiscono di come esso fosse fiorente e dei grandi capitali che gli imprenditori romani investivano per prendervi parte. Più specificamente, la monografia si concentra sull’analisi della vita e dell’evoluzione delle installazioni portuali ubicate sul Mar Rosso e controllate da Roma. Tali porti furono per secoli degli hub internazionali, punti di collegamento tra Oriente e Occidente, le porte attraverso cui le mercanzie orientali entravano nei mercati romani. Mantenere in vita questi insediamenti, collocati in punti remoti e di difficile accesso dell’Impero, richiedeva un grosso sforzo economico, nonché una certa capacità di pianificare investimenti e linee di sviluppo. Nel corso dei secoli, la geografia portuale del Mar Rosso romano cambiò sensibilmente. La maggior parte degli studi finora pubblicati sul tema, ha associato tale cambiamento, avvenuto durante la fase tardoantica di dominazione romana, con un fenomeno di declino del potere romano nella zona. Questo lavoro spinge l’analisi oltre la soglia considerata di declino, indagando approfonditamente le dinamiche economiche dell’era tardoantica, e dimostrando che essa non fu una fase di recessione economica, ma piuttosto di riorganizzazione, spiegandone le caratteristiche e le peculiarità. Il volume si propone quindi di giungere a una nuova e più completa comprensione della politica economica romana nel Mar Rosso tra i secoli I a.C. e VI d.C. / ENGLISH: This volume draws upon the scholarship on the international trade between the Roman Empire and Eastern regions such as Arabia, Ethiopia and India. Such trade has been often described by ancient sources as a flourishing and very expensive one. More in detail, the book focuses on the life and the development of the ports on the Red Sea, controlled by Rome. These ports acted for centuries as international hubs, linking points between West and East, and they were the gates though which the eastern merchandise would reach the Roman markets. Keeping these remote settlements alive required a big effort on the part of the imperial administration, and some degree of planning to choose how and when to invest in the area. So, over the centuries, the geography of such ports changed dramatically. Most works published so far have explained such changes in terms of decline and economic shrinking, due to the “late antique phase” of the Roman Empire. This monograph looks for a different explanation and stretches the analysis into the late antique period, showing hot it was not a period of decline and economic recession, but rather of reorganization. The volume aims finally to reach a new and more full level of understanding of the Roman economic policy in the Red Sea between the first century BC and the sixth AD