Comparative analysis of resonant phonon THz quantum cascade lasers

We present a comparative analysis of a set of GaAs-based THz quantum cascade lasers, based on longitudinal-optical phonon scattering depopulation, by using an ensemble Monte Carlo simulation, including both carrier-carrier and carrier-phonon scattering. The simulation shows that the parasitic injection into the states below the upper laser level limits the injection efficiency and thus the device performance at the lasing threshold. Additional detrimental effects playing an important role are identified. The simulation results are in reasonable agreement with the experimental findings.Comment: 3 pages, 3 figure

FERNANDO MALAVOLTI SPELEOLOGO E GEOLOGO

Fernando Malavolti (Modena, 1913–1954) poliedrica figura di archeologo, geologo e speleologo, a partire dagli anni Trenta del Novecento condusse una instancabile attività di ricerca con indagini sistematiche nel territorio modenese, bolognese e reggiano. Fornì un fondamentale contributo allo studio della preistoria e in particolare del Neolitico dell’Italia settentrionale. Leggendarie rimangono le spedizioni organizzate nel 1938 e nel 1945 per studiare gli aspetti geologici, idrologici, botanici, faunistici, paletnologici e toponomastici dell’area carsica dei Gessi Triassici della Val Secchia (Reggio Emilia). Fra il 1935 e il 1948 affida la narrazione meticolosa di 13 anni di ricerche pionieristiche a una serie di Diari che, grazie alla disponibilità dei figli Mara e Marco, sono pubblicati integralmente in forma digitale, corredati da una trascrizione e da indici dei toponimi e dei nomi di persona. Il volume comprende una serie di saggi scientifici che ripercorrono i diversi campi di ricerca che Malavolti attraversò. Le pagine dei diari riportano anche una inedita testimonianza di Modena negli anni della seconda guerra mondiale e tracciano il rapporto che Malavolti ebbe con Modena

Mutina sepolta: inquadramento geologico dell’area urbana di Modena

Le pianure alluvionali sono tra le aree più popolate al mondo per le favorevoli caratteristiche morfologiche e la ricchezza di risorse. Sono piane formate dai sedimenti abbandonati dai corsi d'acqua durante le piene. Il divagare dei corsi d’acqua e le alluvioni rendono l’evoluzione di questi ambienti estremamente dinamica, caratteristica oggi notevolmente ridotta dalla costruzione degli argini artificiali. Uno dei risultati della complessa evoluzione delle pianure è che le vestigia di antiche civiltà non sono più visibili perché sepolte sotto spessi strati di sedimenti fluviali. Tra gli esempi più noti ricordiamo le civiltà mesopotamiche, dell’Antico Egitto e dell’età del bronzo della Cina. Proprio come a Modena, dove i resti della nostra antica città fondata 2200 anni fa giacciono ben al di sotto dell’area urbana moderna, a circa 5 metri di profondità. Ma com’è possibile che questo sia accaduto? Perché Mutina è sepolta a così grande profondità? La risposta a questa domanda è nascosta all’interno dei sedimenti stessi. I sedimenti rappresentano un vero e proprio archivio di inestimabile valore per ricostruire l’evoluzione degli ambienti e delle caratteristiche climatiche nelle quali hanno vissuto i nostri antenati. E per indagare le modalità con le quali è avvenuta la sedimentazione nella pianura modenese dobbiamo fare riferimento a due recenti fenomeni geologici che hanno sconvolto il nostro territorio: il terremoto del 2012 e l’alluvione del 2014. È proprio grazie allo studio di questi eventi che possiamo scoprire come la città romana sia stata lentamente “inghiottita” nel sottosuolo. Si tratta di una storia per molti versi drammatica, che ci racconta la lotta millenaria dei nostri antenati contro le alluvioni e i terremoti

Evolution of the Po–Alpine River System during the Last 45 Ky Inferred from Stratigraphic and Compositional Evidence (Ostiglia, Northern Italy)

The stratigraphic and compositional study of three sediment cores recovered close to the Po River near Ostiglia provides clues on changes in fluvial dynamics at the transition from the last glacial to the present interglacial. Upper Pleistocene units are dominated by sands with high content in volcanic lithics, denoting high sediment supply from the south-Alpine fluvio-glacial tributary system. The Early–Mid Holocene unit, peat-rich and barren in fluvial sands, results from low sediment supply and waterlogging, encompassing the maximum marine ingression. The Late Holocene unit, characterized by fluvial-channel sands with lower content in volcanics and relatively abundant metamorphic lithics, records the Po River sedimentation since the Late Bronze Age. Late Holocene sands show a lower content in siliciclastic lithic fragments (supplied mainly by Apennine tributaries) compared to modern Po River sands. This distinctive composition could reflect the diversion of Apennine sediments into a southern Po River branch during the Late Bronze Age and into an Apennine collector flowing south of Ostiglia during Roman times and the Middle Ages. The integrated stratigraphic-compositional methods used in this study permitted to reconstruct the major climate-related changes in sediment dispersal and may be potentially applied to other alluvial and coastal settings

Are fluid inclusions in gypsum reliable paleoenvironmental indicators? An assessment of the evidence from the Messinian evaporites

The paleosalinity of water from which the gypsum precipitated during the Messinian salinity crisis is a controversial issue. Recent microthermometry studies on primary fluid inclusions in gypsum provided very low salinity values not compatible with precipitation from seawater, and suggested strong mixing between seawater and nonmarine waters enriched in calcium sulfate. We applied a new microthermometric protocol on gypsum crystals from nine Mediterranean sections that were experimentally stretched to measure a larger population of fluid inclusions. The results show salinities ranging from 9 to 238 wt‰ NaCl equivalent, largely falling within the evaporation path of normal seawater. The data from previous studies were obtained mostly from those fluid inclusions capable of nucleating a stable bubble after a weak stretching, which probably correspond to those having a lower salinity acquired through post-depositional crack-and-seal processes. Our data suggest instead that the primary gypsum precipitated from a marine brine, later modified by post-trapping processes during tectonics and exhumation

Rare KIT (CD117) expression in multiple myeloma abrogates the usefulness of imatinib mesylate treatment

Background: Imatinib mesylate blocks the tyrosine kinase activity of KIT (CD117) and is an effective treatment for gastrointestinal stromal tumors. In multiple myeloma, KIT expression has been detected by flow cytometry in about 33% of specimens, but no previous immunohistochemical assessment has yet been made of the expression pattern of KIT. Materials and methods: We performed immunohistochemical analyses of 100 patients, including 72 with multiple myeloma (MM), 8 with lymphoplasmacytic lymphoma (LPL), 10 with monoclonal gammopathy of undetermined significance (MGUS) and 10 with reactive plasmocytosis. One KIT-positive MM was sequenced using polymerase chain reaction analysis. Results: In MM, only 2 cases (2.8%) were KIT positive. The great majority of the cases (97, 2%) did not express the KIT receptor tyrosine kinase. No mutation of the c-kit gene was detected. Conclusions: KIT expression is a rare event in MM and not detectable in MGUS and LPL. Therefore, treatment with imatinib is unlikely to be effective in these patient

Alice in wonderland: experimental jurisprudence on the internal point of view

Humans have this extraordinary cognitive ability: They imagine inexistent objects, they treat them as if they were real, and by doing so they make them real. They thus give rise to a shared institutional reality that enables them to cooperate in ways that would be impossible otherwise. In this paper, we would like to revisit the account that HLA Hart gives of the practice of collective acceptance that makes a legal system possible. We try to provide an explanation of what Hart calls the 'internal point of view', on the basis of experiments on institutional concepts, drawing on the paradigm known as 'embodied cognition'. Experts and non-experts in law rated the role of several cognitive dimensions for a list of words referring to two kinds of abstract concepts (institutional and theoretical/scientific) and two kinds of concrete ones (food and artifact). Institutional concepts were distinguished into pure-institutional (e.g., 'contract', 'state', 'property') and meta-institutional (e.g., 'norm', 'duty', 'justice'). The results provide an empirical account of how our way of thinking about institutions changes as we acquire expertise in the legal field, thus shading light on the cognitive underpinnings of the 'internal point of view'

Sediment stacking pattern effect on sand liquefaction inferred from full-scale experiments in the Emilia alluvial plain (Italy)

The geometry and the depositional configuration of sand bodies affected by the 2012 Emilia earthquakes (Bondeno site, northern Italy) were reconstructed and the role of the sediment stacking pattern was tested using data from full-scale blast experiments. The research integrates remote sensing and surface geological mapping, subsurface investigations including stratigraphic coring and cone penetration tests, grain-size and petrography of sands, geotechnical and geophysical monitoring. Data are compared with the Mirabello blast test site, also in the epicentral area. The results highlight the preeminent role of sediment heterogeneity and their mechanical and compositional properties in modulating liquefaction in alluvial settings. The lateral confinement of the buried sandy bodies, their thickness, and the occurrence of a thick non-liquefiable crust influence the dissipation of the excess pore water pressure, as indicated by the blast monitoring, and therefore the duration of liquefaction phenomena, according to the local stratigraphic architecture