768 research outputs found
Critical current and topology of the supercooled vortex state in NbSe2
We study the behavior of the critical current, Ic(H,T), of pure and Fe doped
NbSe2 crystals in the denominated disordered vortex region, limited by the
critical field Hc2(T) and the field Hp(T) at which the peak effect in Ic(H,T)
is detected. The critical current follows an individual pinning response as
demonstrated by its field independent universal function of the superfluid
density. Transport measurements combined with Bitter decorations show no
evidence of the existence of an amorphous phase in the high temperature region.Comment: 7 pages, figures included. Submitted to Phys. Rev.
Avalanches and Self-Organized Criticality in Superconductors
We review the use of superconductors as a playground for the experimental
study of front roughening and avalanches. Using the magneto-optical technique,
the spatial distribution of the vortex density in the sample is monitored as a
function of time. The roughness and growth exponents corresponding to the
vortex landscape are determined and compared to the exponents that characterize
the avalanches in the framework of Self-Organized Criticality. For those
situations where a thermo-magnetic instability arises, an analytical non-linear
and non-local model is discussed, which is found to be consistent to great
detail with the experimental results. On anisotropic substrates, the anisotropy
regularizes the avalanches
Regulation of the expression of the Kluyveromyces lactis PDC1 gene: carbon source-responsive elements and autoregulation
The yeast Kluyveromyces lactis has a single structural gene coding for pyruvate decarboxylase (KIPDC1). In order to study the regulation of the expression of KIPDC1, we have sequenced (EMBL Accession No. Y15435) its promoter and have fused the promoter to the reporter gene lacZ from E. coli. Transcription analysis in a Klpdc1 delta strain showed that KIPDC1 expression is subject to autoregulation. The PDC1 gene from Saccharomyces cerevisiae was able to complement the Rag- phenotype of the Klpdc1 delta mutant strain and it could also repress transcription of the KIPDC1-lacZ fusion on glucose. A deletion analysis of the promoter region was performed to study carbon source-dependent regulation and revealed that at least two cis-acting regions are necessary for full induction of gene expression on glucose. Other cis-elements mediate repression on ethanol
Dynamics of stripe patterns in type-I superconductors subject to a rotating field
The evolution of stripe patterns in type-I superconductors subject to a
rotating in-plane magnetic field is investigated magneto-optically. The
experimental results reveal a very rich and interesting behavior of the
patterns. For small rotation angles, a small parallel displacement of the main
part of the stripes and a co-rotation of their very ends is observed. For
larger angles, small sideward protrusions develop, which then generate a zigzag
instability, ultimately leading to a breaking of stripes into smaller segments.
The short segments then start to co-rotate with the applied field although they
lag behind by approximately . Very interestingly, if the rotation is
continued, also reconnection of segments into longer stripes takes place. These
observations demonstrate the importance of pinning in type-I superconductors.Comment: To appear in Phys. Rev.
Actuator Fault Reconstruction via Dynamic Neural Networks for an Autonomous Underwater Vehicle Model
This paper proposes the development of a scheme for the fault diagnosis of the actuators of a simulated model accurately representing the behaviour of an autonomous underwater vehicle. The Fossen model usually adopted to describe the dynamics of the underwater vehicle has been generalised in this paper to take into account time-varying sea currents. The proposed fault detection and isolation strategy uses a data-driven approach relying on multi-layer perceptron neural networks that include auto-regressive exogenous prototypes that provide the fault reconstruction. These tools are thus exploited to design a bank of dynamic neural networks for residual generation that are trained on the basis of the input and outputmeasurements acquired from the simulator. In this work, the residuals are designed to represent the reconstruction of the fault signals themselves. Moreover, the neural network bank is also able to perform the isolation task, in case of simultaneous and concurrent faults affecting the actuators. The paper firstly describes the steps performed for deriving the proposed fault diagnosis solution. Secondly, the effectiveness of the scheme is demonstrated by means of high-fidelity simulations of a realistic autonomous underwater vehicle, in the presence of faults and marine current
Corneal Melting Two Weeks after Pterygium Excision with Topical Mitomycin C: Successfully Treated with Lamellar Keratoplasty and Amnion Membrane Transplantation
PURPOSE: To report the management of a case of corneal melting two weeks after pterygium excision with intraoperative topical mitomycin C (MMC).
METHODS: Case report.
RESULTS: A 57-year-old male was referred to our Department for therapy of rapidly progressive corneal melting two weeks after primary pterygium surgery with MMC (0.2 mg/ml) in September 2009. Initial treatment consisted of topical and systemic immunosuppression along with topical antibiotics. Eight days after presentation, the patient underwent successful lamellar keratoplasty and amnion membrane transplantation. Subconjunctival injection of triamcinolone (40 mg/ml) and topical bevacizumab were used to manage the increased fibrovascular activity around the site of the former pterygium.
CONCLUSION: Topical use of MMC during pterygium surgery may be related to serious postoperative complications such as progressive inflammatory corneal melting. The etiology may be multifactorial, which is related to MMC-induced inflammation and/or induced apoptosis. A therapeutic option is the described combination of systemic and local anti-inflammatory treatment along with lamellar keratoplasty and amniotic membrane transplantation. Adjunctive therapy may be needed if recurrence occurs
Dendritic flux penetration in Pb films with a periodic array of antidots
We explore the flux-jump regime in type-II Pb thin films with a periodic
array of antidots by means of magneto-optical measurements. A direct
visualization of the magnetic flux distribution allows to identify a rich
morphology of flux penetration patterns. We determine the phase boundary
between dendritic penetration at low temperatures and a smooth flux
invasion at high temperatures and fields. For the whole range of fields and
temperatures studied, guided vortex motion along the principal axes of the
square pinning array is clearly observed. In particular, the branching process
of the dendrite expansion is fully governed by the underlying pinning topology.
A comparative study between macroscopic techniques and direct local
visualization shed light onto the puzzling and independent magnetic
response observed at low temperatures and fields. Finally, we find that the
distribution of avalanche sizes at low temperatures can be described by a power
law with exponent
Metabolic aspects of cardiovascular diseases: Is FoxO1 a player or a target?
The O subfamily of forkhead (FoxO) 1 is a crucial regulator of cell metabolism in several tissues, including the heart, where it is involved in cardiac regulation of glucose and lipid metabolic pathways, and endothelium, controlling the levels of some relevant biomarkers in atherosclerotic process. Despite the growing understanding of FoxO1 biology, the metabolic consequences of FoxO1 modifications and its implication in CVD, atherosclerosis and T2DM are still not incompletely described. In this review we discuss how FoxO1 affects cardiovascular pathophysiology and which of its effects should be restrained or enhanced to preserve endothelial and heart functions
Weiterer Kariesrückgang bei Schweizer Rekruten von 1996 bis 2006
Rekruten der Rekrutenschule
Thun (N = 606) wurden im Jahr 2006
mit einer standardisierten Methode zahnmedizinisch
untersucht. Die Resultate wurden mit
denjenigen aus früheren Erhebungen (1985
und 1996) verglichen.
Der DM6FT-Wert betrug im Jahr 2006 im
Durchschnitt 3,11; im Jahr 1996 lag er noch
deutlich höher (4,95). Dies entspricht einem
Kariesrückgang von 37%. Der beobachtete
Kariesrückgang konnte nur zum Teil erklärt
werden.
Rekruten, die rauchten, zeigten einen erhöhten
Kariesbefall.
Rekruten aus der Deutschschweiz, die in Kindergarten
und Primarschule von Schulzahnpflege-
Instruktorinnen betreut worden waren,
unterschieden sich im Kariesbefall nicht von
den Rekruten aus der Romandie
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