Quantum transport through mesoscopic disordered interfaces, junctions, and multilayers

The study explores perpendicular transport through macroscopically inhomogeneous three-dimensional disordered conductors using mesoscopic methods (real-space Green function technique in a two-probe measuring geometry). The nanoscale samples (containing $\sim1000$ atoms) are modeled by a tight-binding Hamiltonian on a simple cubic lattice where disorder is introduced in the on-site potential energy. I compute the transport properties of: disordered metallic junctions formed by concatenating two homogenous samples with different kinds of microscopic disorder, a single strongly disordered interface, and multilayers composed of such interfaces and homogeneous layers characterized by different strength of the same type of microscopic disorder. This allows us to: contrast resistor model (semiclassical) approach with fully quantum description of dirty mesoscopic multilayers; study the transmission properties of dirty interfaces (where Schep-Bauer distribution of transmission eigenvalues is confirmed for single interface, as well as for the stack of such interfaces that is thinner than the localization length); and elucidate the effect of coupling to ideal leads (``measuring apparatus'') on the conductance of both bulk conductors and dirty interfaces When multilayer contains a ballistic layer in between two interfaces, its disorder-averaged conductance oscillates as a function of Fermi energy. I also address some fundamental issues in quantum transport theory--the relationship between Kubo formula in exact state representation and ``mesoscopic Kubo formula'' (which gives the zero-temperature conductance of a finite-size sample attached to two semi-infinite ideal leads) is thoroughly reexamined by comparing their answers for both the junctions and homogeneous samples.Comment: 18 pages, 17 embedded EPS figure

From shallow to very shallow image of the highly active Kefalonia - Zakynthos fault system

4 pages, 2 figuresIn May 2022 and June 2023 two oceanographic cruises were carried out around the Ionian Islands with the aim of defining the real geometry of the strike-slip fault system of Kefalonia and of the reverse faults present south of Zakynthos. The acquired multidisciplinary and multiresolution data will also allow to understand the dynamics of the area offshore the Peoloponnese peninsula, the deformation of the surface sediments at the transition of the two systems, i.e. from reverse fault system to strike-slip fault system, and the relationship between the recorded seismicity and mapped fault activity. To date, the analysis of the processed data has allowed us to define the tectonic and morphological complexity of the fault system affecting the investigated area. [...]Thanks to the CNR for supporting the cruise with time ship, IONIANS 2022 project. Interpretation of seismic profile has been done using the Kindgom IHS Markit. Poseidon project has been supported by Eurofleet+ SEA02_13_POSEIDONPeer reviewe

Is Left Innominate Vein Ligation during Aortic Arch Surgery Always Safe? A Case Report

Ligation of the left innominate vein (LIV) expands the surgeon’s surgical field for ascending aorta and aortic arch procedures. Although it is considered a safe technique by most surgeons in that it is associated with only minor drawbacks, conflicting views exist regarding this method. We herein describe a 70-year-old woman who underwent ascending aorta replacement due to an aneurysm with subsequent cerebral dysfunction caused by extended brain edema, possibly related to LIV ligation, leading to her death. © 2022 Tehran University of Medical Sciences

POSEIDON: New data on offshore structures in the west Peloponnese - Ionian Islands Domain and implications for seismic hazards

8th International Colloquium on Historical Earthquakes, Palaeo- Macroseismology and Seismotectonics, Past earthquakes and advances in seismology for informed risk decision-making, 17-20 September 2023, Lixouri, Kefalonia Island, Greece.-- 4 pages, 2 figuresOur cruise POSEIDON from 10 to 22 June 2023, on Research Vessel (R/V) Laura Bassi, aimed at mapping the tectonic structure of arguably one of the most complex and comparatively little evaluated regions, with demonstrated seismic hazard, in the Mediterranean. The region encompassing this tectonic domain extends from the western Peloponnese across the Ionian Islands (Figure 1). Here, a complex fault system with numerous strands has developed in a region with dramatic lateral changes in deformation rates. This system has produced numerous large earthquakes, mostly offshore, recorded during the past few decades in the onshore Greek national seismological network(Hadad et al., 2020). However, the large Cephalonia 1953 Mw~6.8 event (Stiros et al., 1994) was recorded in comparatively few stations only. This earthquake is possibly the most destructive seismic event in recent Greek history, causing the collapse of ~85% of all buildings on Kefalonia, ~1000 deaths, and ~145k people homeless, (Saranga, 2017; Hore, 2019). The limited data on the 1953 earthquake has made it poorly understoodcomparatively with more recent, albeit less destructive events. The epicentreof the 1953 event is poorly located, and the location and dimensions of the causative fault are unconstrained. Likewise, the thrust fault focal mechanism, located E or SE of Kefalonia, has a hypocenter depth poorly defined from <50 km to <20 km, depending on the analysis. Surface geology studies of the islands interpret active shallow thrusting(Underhill, 1989), and it has been proposed that the 1953 event ruptured several of those faults. The goal of POSEIDON is to determine region fault system structure and kinematics. [...]Peer reviewe

The dominant role of CD8(+) dendritic cells in cross-presentation is not dictated by antigen capture

Mouse spleens contain three populations of conventional (CD11c(high)) dendritic cells (DCs) that play distinct functions. The CD8(+) DC are unique in that they can present exogenous antigens on their MHC class I molecules, a process known as cross-presentation. It is unclear whether this special ability is because only the CD8(+) DC can capture the antigens used in cross-presentation assays, or because this is the only DC population that possesses specialized machinery for cross-presentation. To solve this important question we examined the splenic DC subsets for their ability to both present via MHC class II molecules and cross-present via MHC class I using four different forms of the model antigen ovalbumin (OVA). These forms include a cell-associated form, a soluble form, OVA expressed in bacteria, or OVA bound to latex beads. With the exception of bacterial antigen, which was poorly cross-presented by all DC, all antigenic forms were cross-presented much more efficiently by the CD8(+) DC. This pattern could not be attributed simply to a difference in antigen capture because all DC subsets presented the antigen via MHC class II. Indeed, direct assessments of endocytosis showed that CD8(+) and CD8(−) DC captured comparable amounts of soluble and bead-associated antigen, yet only the CD8(+) DC cross-presented these antigenic forms. Our results indicate that cross-presentation requires specialized machinery that is expressed by CD8(+) DC but largely absent from CD8(−) DC. This conclusion has important implications for the design of vaccination strategies based on antigen targeting to DC