993 research outputs found
Resonant Transport in Nb/GaAs/AlGaAs/GaAs Microstructures
Resonant transport in a hybrid semiconductor-superconductor microstructure
grown by MBE on GaAs is presented. This structure experimentally realizes the
prototype system originally proposed by de Gennes and Saint-James in 1963 in
\emph{all}-metal structures. A low temperature single peak superimposed to the
characteristic Andreev-dominated subgap conductance represents the mark of such
resonant behavior. Random matrix theory of quantum transport was employed in
order to analyze the observed magnetotransport properties and ballistic effects
were included by directly solving the Bogoliubov-de Gennes equations.Comment: 7 pages REVTeX, 4 figures, to be published by World Scientific in
Proceedings of International Symposium on Mesoscopic Superconductivity and
Spintronics (NTT R&D Center Atsugi, Japan, March 2002
Smoothing semi-smooth stable Godeaux surfaces
We show that all the semi-smooth stable complex Godeaux surfaces, classified in
[M. Franciosi, R. Pardini and S. Rollenske, Ark. Mat. 56 (2018), no. 2, 299–317], are
smoothable and that the moduli stack is smooth of the expected dimension 8 at the
corresponding points
I-surfaces with one T-singularity
We classify normal stable surfaces with KX2=1, pg= 2 and q= 0 with a unique singular point which is a non-canonical T-singularity, thus exhibiting two divisors in the main component and a new irreducible component of the moduli space of stable surfaces MÂŻ 1 , 3
Changing the approach to sustainable constructions: An adaptive mix-design calibration process for earth composite materials
One major drawback of excavation earth-based composite construction materials is the variability in excavation earth characteristics from site to site. This variability can affect certain physical properties, and, in turn, the design models used to create a structure. To solve this problem, a methodology has been developed to predict the physical properties of earth-based composites for any mix-design variation, which enables a robust structural design process. This new methodology has been tested for Shot-earth, a new class of earth-based composite material made using high rates of excavation earth, aggregates, and a low rate of stabilization if needed. Shot-earth is placed using a high-speed dry-mix process. The methodology was tested by preparing small, inexpensive specimens through a process that simulates the
dry-process used to fabricate Shot-earth in the field. An adaptive technique, used in conjunction with the experimental methodology, allows for the identification of the variant of possible Shot-earth mix-designs that provides optimal physical properties for a specific project. This technique is potentially applicable to any type of earth-based composite. The proposed methodology’s reliability enables a fast and cost-effective detailing of Shot-earth constructions
Comparative Analysis of Sliding Resistance of Different Lingual Systems
Objective: To analyse and compare the frictional properties of 4 lingual systems combined with two types of stainless steel archwire (0.016x0.022, 0.018x0.025) and a 0.018x0.025 TMA archwire by simulating different misalignment situations in vitro. Material and Methods: Five randomly chosen brackets from each system (e-Brace, Harmony, Incognito, and STb) were used for the measurements and to simulate an upper first premolar extraction case. The friction tests were performed using a material testing machine in combination with a specialized test rig. Results: The lowest absolute friction values were found with the 0.016x0.022 SS wire in a passive configuration. STb provided the lowest mean friction, while Harmony brackets displayed the highest friction. The TMA Beta Titanium wire showed the highest friction values, but maintained proportions similar to those of the other wires as tip and torsion increased. Conclusion: The type of bracket has a significant impact on friction, and there is a positive correlation between mesiodistal bracket width and resistance to sliding. The archwire sections and materials and the vertical displacement, also significantly affect the friction generated by the system
Geochemical characteristics and mantle sources of the Oligo-Miocene primitive basalts from Sardinia: The role of subduction components.
During the Oligo-Miocene, the Island of Sardinia was covered by the products of voluminous magmatic activity, with a typical subduction-related signature. The mafic rocks of the Montresta (north) and Arcuentu (south) volcanic districts include primitive high MgO basalts whose trace element and Sr-, Nd- and Pb-isotope compositions constrain the nature and role of subduction-related components in the Tertiary Sardinian volcanism. The geochemical and isotopic data require an approximate degree of partial melting of 15% of a MORB-like depleted mantle prior to enrichment, and the input of two subduction components in the mantle wedge consisting of fluids from subducted oceanic crust (altered MORB) and fluids from subducted sediments. Ratios among trace elements which are variably compatible with fluid and melt phases (i.e. Th/Pb, Th/Nd and Sr/Nd) exclude the contribution of melts from the subducted slab. Models based on isotopic ratios indicate that the pre-subduction depleted mantle source of Sardinia magmas was enriched by 0.1-0.5% MORB fluid and less than 0.1% sediment fluid. The geochemical and isotopic compositions of the Montresta volcanic rocks are homogeneous, whereas those of the Arcuentu show quite heterogeneous characters, suggesting variations in mantle source over the long time-span (about 13 Ma) of volcanic activity in this district
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