455 research outputs found
Two-dimensional superconductivity at the (111)LaAlO/SrTiO interface
We report on the discovery and transport study of the superconducting ground
state present at the (111)LaAlO/SrTiO interface. The superconducting
transition is consistent with a Berezinskii-Kosterlitz-Thouless transition and
its 2D nature is further corroborated by the anisotropy of the critical
magnetic field, as calculated by Tinkham. The estimated superconducting layer
thickness and coherence length are 10 nm and 60 nm, respectively. The results
of this work provide a new platform to clarify the microscopic details of
superconductivity at LaAlO/SrTiO interfaces, in particular in what
concerns the link with orbital symmetry.Comment: 4 pages, 4 figure
Field-Dependent Differential Susceptibility Studies on Tetrathiafulvalene-AuS\u3csub\u3e4\u3c/sub\u3eC\u3csub\u3e4\u3c/sub\u3e(CF\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e4\u3c/sub\u3e: Universal Aspects of the Spin-Peierls Phase Diagram
An applied magnetic field is known to produce novel effects in the phase behavior of magnetoelastic spin-Peierls systems. Hence we report measurements of the differential susceptibility (χ) and magnetization (M) in fields up to 40 kOe (4 T) on the spin-Peierls compound tetrathiafulvalene (TTF)-AuS4C4(CF3)4 in the temperature region (1.1K \u3c- T \u3c- 4.2K). This range of field and temperature encompasses an interesting phase region, including the zero-field spin-Peierls transition temperature Tc(0)=2.03 K. The measurements of the differential (ac) susceptibility provide a more sensitive probe of the transition behavior than magnetization measurements. The first definitive evidence for significant deviations from mean-field critical behavior appear in these measurements, and the appropriate criteria for determining the precise location of the transitions are thus provided by the thermodynamic theory of λ transitions. Using the new criteria, qualitative and even quantitative agreement is obtained with current theories of the field dependence of spin-Peierls transitions. A novel contour plot of χac in the H − T plane is shown to be useful for the delineation of the global phase-transition behavior. An investigation of the role of relaxation effects in χac relative to the nature of the phase boundaries is conducted. A major feature is the observation of a striking degree of universality in the phase behavior of three spin-Peierls systems TTF-AuS4C4(CF3)4, TTF-AuS4C4(CF3)4, and methylethylmorpholinium di-tetracyanoquinodimethane [MEM-(TCNQ)2]. hese universal features are preserved through considerable differences in lattice structure and a variation in Tc(0) of a factor of 10
Laser texturing of a St. Jude Medical Regent (TM) mechanical heart valve prosthesis:the proof of concept
OBJECTIVES: The liquid-solid interactions have attracted broad interest since solid surfaces can either repel or attract fluids, configuring a wide spectrum of wetting states (from superhydrophilicity to superhydrophobicity). Since the blood-artificial surface interaction of bileaf-let mechanical heart valves essentially represents a liquid-solid interaction, we analysed the thrombogenicity of mechanical heart valve prostheses from innovative perspectives. The aim of the present study was to modify the surface wettability of standard St. Jude Medical Regent (TM) occluders. METHODS: Four pyrolytic carbon occluders were irradiated by means of ultra-short pulse laser, to create 4 different nanotextures (A-D), the essential prerequisite to achieve superhydrophobicity. The static surface wettability of the occluders was qualified by the contact angle (theta) of 2 mu l of purified water, using the sessile drop technique. The angle formed between the liquid-solid and the liquid-vapour interface was the contact angle and was obtained by analysing the droplet images captured by a camera. The morphology of the occluders was characterized and analysed by a scanning electron microscope at different magnifications. RESULTS: The scanning electron microscope analysis of the textures revealed 2 different configurations of the pillars since A and B showed well-rounded shaped tops and C and D flat tops. The measured highest contact angles were comprised between 108.1 degrees and 112.7 degrees, reflecting an improved hydrophobicity of the occluders. All the textures exhibited, to different extents, an orientation (horizontal or vertical), which was strictly related to the observed anisotropy. CONCLUSIONS: In this very early phase of our research, we were able to demonstrate that the intrinsic wettability of pyrolytic carbon occluders can be permanently modified, increasing the water repellency
Reversing Blood Flows Act through klf2a to Ensure Normal Valvulogenesis in the Developing Heart
Heart valve anomalies are some of the most common congenital heart defects, yet neither the genetic nor the epigenetic forces guiding heart valve development are well understood. When functioning normally, mature heart valves prevent intracardiac retrograde blood flow; before valves develop, there is considerable regurgitation, resulting in reversing (or oscillatory) flows between the atrium and ventricle. As reversing flows are particularly strong stimuli to endothelial cells in culture, an attractive hypothesis is that heart valves form as a developmental response to retrograde blood flows through the maturing heart. Here, we exploit the relationship between oscillatory flow and heart rate to manipulate the amount of retrograde flow in the atrioventricular (AV) canal before and during valvulogenesis, and find that this leads to arrested valve growth. Using this manipulation, we determined that klf2a is normally expressed in the valve precursors in response to reversing flows, and is dramatically reduced by treatments that decrease such flows. Experimentally knocking down the expression of this shear-responsive gene with morpholine antisense oligonucleotides (MOs) results in dysfunctional valves. Thus, klf2a expression appears to be necessary for normal valve formation. This, together with its dependence on intracardiac hemodynamic forces, makes klf2a expression an early and reliable indicator of proper valve development. Together, these results demonstrate a critical role for reversing flows during valvulogenesis and show how relatively subtle perturbations of normal hemodynamic patterns can lead to both major alterations in gene expression and severe valve dysgenesis
Generalized Quantifiers on Dependent Types: A System for Anaphora
We propose a system for the interpretation of anaphoric relationships between
unbound pronouns and quantifiers. The main technical contribution of our
proposal consists in combining generalized quantifiers with dependent types.
Empirically, our system allows a uniform treatment of all types of unbound
anaphora, including the notoriously difficult cases such as quantificational
subordination, cumulative and branching continuations, and 'donkey anaphora'.Comment: 40 pages; final versio
Нарушение межличностных отношений супругов при отдаленных последствиях закрытой черепно−мозговой травмы у мужа
Методами психодиагностического исследования выявлены закономерности нарушения межличностной адаптации супругов при отдаленных последствиях военной закрытой черепно−мозговой травмы у мужа.The methods of psychodiagnosis were used to reveal the regularities of interpersonal adaptation disorders in spouses at long−term sequelae of military closed brain injury in the husband
Trichoblastic carcinosarcoma with panfollicular differentiation (panfollicular carcinosarcoma) and CTNNB1 (beta-catenin) mutation
We present a case of trichoblastic carcinosarcoma with panfollicular differentiation. An 80-year-old man presented with a lesion on the left ear, which ha
- …