Universal Rashba Spin Precession of Two-Dimensional Electrons and Holes

We study spin precession due to Rashba spin splitting of electrons and holes in semiconductor quantum wells. Based on a simple analytical expression that we derive for the current modulation in a broad class of experimental situations of ferromagnet/nonmagnetic semiconductor/ferromagnet hybrid structures, we conclude that the Datta-Das spin transistor (i) is feasible with holes and (ii) its functionality is not affected by integration over injection angles. The current modulation shows a universal oscillation period, irrespective of the different forms of the Rashba Hamiltonian for electrons and holes. The analytic formulas approximate extremely well exact numerical calculations of a more elaborate Kohn--Luttinger model.Comment: 7 pages, 2 eps figures included, minor change

Presentación del editor

El presente dossier de Rubrica Contemporanea recoge los artículos fruto de las intervenciones presentadas en el seminario "Escriure Història: tàctiques i tècniques", organizado por el Departament d'Història Moderna i Contemporània de la Universitat Autònoma de Barcelona y celebrado en la misma universidad los días 15, 16 y 17 de mayo de 2012. El objetivo que se prefijaron sus organizadores era el de proporcionar a los estudiantes del programa de doctorado "Historia comparada, política y social" una serie de puntos de vista que les ayudaran a tener una idea más clara acerca del largo y laborioso proceso de escritura de la tesis doctoral. Y éste es también el objetivo del dossier, dejando claro desde ahora el elemento que comparten todos sus textos: su carácter más práctico que teórico. En efecto, no se trataba de sustituir a aquel tipo de literatura científica cuyo fin es elaborar propuestas detalladas para redactar una disertación académica, sino de complementarla con reflexiones sobre la escritura académica que nacieran de la formación cultural y la labor profesional de los autores. Reflexiones, en suma, que fueran expresión de lo vivido y experimentado en su práctica historiográfica y que pudiesen estimular el quehacer intelectual del doctorando en Historia

High performance Tunnel Field Effect Transistors based on in-plane transition metal dichalcogenide heterojunctions

In-plane heterojunction tunnel field effect transistors based on monolayer transition metal dichalcogenides are studied by means of self-consistent non-equilibrium Green's functions simulations and an atomistic tight-binding Hamiltonian. We start by comparing several heterojunctions before focusing on the most promising ones, i.e WTe2-MoS2 and MoTe2-MoS2. The scalability of those devices as a function of channel length is studied, and the influence of backgate voltages on device performance is analysed. Our results indicate that, by fine-tuning the design parameters, those devices can yield extremely low sub-threshold swings (below 5mV/decade) and Ion/Ioff ratios higher than 1e8 at a supply voltage of 0.3V, making them ideal for ultra-low power consumption.Comment: 10 page

Nullo Glauco Lepori: note biografiche

Breve biografia del professor Nullo Glauco Lepori, direttore dell'Istituto di Zoologia dell'Università degli studi di Sassari e poi preside della Facoltà di Scienze

Kelepçe Center

Taha Toros Arşivi, Dosya No: 3-Eminönü-Sirkeciİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) Istanbul Development Agency (TR10/14/YEN/0033

Sant’Antioco sulcitano: il culto, il santuario, le immagini dal tardoantico al barocco

La chiesa e santuario di Sant’Antioco è ubicata nell’omonima isola situata nella regione del Sulcis in Sardegna. Il culto del santo martire titolare della chiesa sulcitana è testimoniato da un’epigrafe attribuibile al VII secolo, collocata all’interno dell’edificio sino al XVII secolo. La venerazione di Antioco in Sardegna sembra più remota della data riferibile all’iscrizione, ipotesi suffragata anche dal recente ritrovamento di due sigilli plumbei che recano il nome del santo, databili al VI secolo. Nel contributo si fa un excursus sulla venerazione del martire nell’isola, in particolare si passano in rassegna le immagini più rappresentative di Antioco comprese in un arco cronologico che va dal VI al XVIII secolo. Nello scritto si propone anche una lettura delle immagini del santo attraverso le fonti scritte del XVII secolo Parole chiave: Sardegna, Sulcis, Sant’Antioco, Scultura, Dipinto, Epigrafe, SigilloThe church and shrine of Sant’Antioco is located in the homonymous island in the region of Sardinia called Sulcis. The cult of the martyred saint to whom the church is evidenced by an inscription attributed to the seventh century, placed inside the building until the seventeenth century. The veneration of Antioco in Sardinia seems more remote date refers to enrollment, hypothesis supported by the recent discovery of two leaden seals bearing the name of the saint dating to the sixth century. The contribution make a digression on the veneration of the martyr in the island, in particular the text review the most representative images of Antioco included in a period of time ranging from VI to XVIII century. The paper also proposes a reading of images of the saint through the written sources of the seventeenth century

Production of proteolytic enzymes by selected microorganisms

Předložená práce se zabývala studiem možností mikrobiální produkce proteolytických enzymů používaných v řadě průmyslových aplikací. K produkci mikrobiálních proteolytických enzymů byla využita průmyslová bakterie Bacillus subtilis. V průběhu kultivace byl studován růst biomasy a produkce proteolytických enzymů v závislosti na typu substrátu a aplikaci vybraných stresových faktorů (osmotického šoku, peroxidu vodíku a ethanolu). Nejvyšší produkce biomasy byla dosažena v koncentrovaném BM médiu ve 32. hodině kultivace. Výtěžek představoval 1,11 g/l. Nejvyšší proteázová aktivita (88,28 U/ml) byla stanovena ve stejném kultivačním médiu a čase. Na základě vyhodnocení výsledků stresových experimentů lze konstatovat, že převážná většina použitých stresových faktorů působí na bakteriální kulturu toxicky již v nízkých koncentracích.Presented work was focused on study of microbial production of proteolytic enzymes used in many industrial applications. Bacterium Bacillus subtilis was used for laboratory production of microbial proteolytic enzymes. During cultivation production of biomass and proteolytic enzymes were studied influence of substrate type and stress factor application (osmotic shock, hydrogen peroxide and ethanol) was tested too. The highest concentration of biomass was measured in concentrated BM medium after 32 hours of cultivation. Biomass yield was 1.11 g/l. The highest protease activity (88.28 U/ml) was obtained in the same cultivation medium and time of cultivation. According to results of stress experiments it can be concluded that most of used stress factors exhibited a toxic effects to bacterial culture even at low concentrations.