1,587 research outputs found
The effect of magnetic islands on ITG turbulence driven transport
In this work, we address the question of the influence of magnetic islands on
the perpendicular transport due to steady-state ITG turbulence on the energy
transport time scale. We demonstrate that turbulence can cross the separatrix
and enhance the perpendicular transport across magnetic islands. As the
perpendicular transport in the interior of the island sets the critical island
size needed for growth of neoclassical tearing modes, this increased transport
leads to a critical island size larger than that predicted from considering
collisional conductivities, but smaller than that using anomalous effective
conductivities.
We find that on Bohm time scales, the turbulence is able to re-establish the
temperature gradient across the island for islands widths , the turbulence correlation length. The reduction in the island
flattening is estimated by comparison with simulations retaining only the
perpendicular temperature and no turbulence. At intermediate island widths,
comparable to , turbulence is able to maintain finite
temperature gradients across the island
Plasma turbulence simulations with X-points using the flux-coordinate independent approach
In this work, the Flux-Coordinate Independent (FCI) approach to plasma
turbulence simulations is formulated for the case of generic, static magnetic
fields, including those possessing stochastic field lines. It is then
demonstrated that FCI is applicable to nonlinear turbulent problems with and
without X-point geometry. In particular, by means of simulations with the
FENICIA code, it is shown that the standard features of ITG modes are recovered
with reduced toroidal resolution. Finally, ITG turbulence under the influence
of a static island is studied on the transport timescale with ITER-like
parameters, showing the wide range of applicability of the method
Implementation of a three-qubit quantum error correction code in a cavity-QED setup
The correction of errors is of fundamental importance for the development of
contemporary computing devices and of robust communication protocols. In this
paper we propose a scheme for the implementation of the three-qubit quantum
repetition code, exploiting the interaction of Rydberg atoms with the quantized
mode of a microwave cavity field. Quantum information is encoded within two
circular Rydberg states of the atoms and encoding and decoding process are
realized within two separate microwave cavities. We show that errors due to
phase noise fluctuations could be efficiently corrected using a
state-of-the-art apparatus.Comment: 9 pages, 5 figures. This is v2. Some misprints corrected, conclusions
section extended, refs added. Accepted for publication on PR
Cu-catalyzed Si-NWS grown on “carbon paper” as anodes for Li-ion cells
The very high theoretical capacity of the silicon (4200mAh/g more than 10 times larger than graphite), environmental-friendly, abundant and low-cost, makes it a potential candidate to replace graphite in high energy density Li-ion batteries. As a drawback, silicon suffers from huge volume changes (300%) on alloying and dealloying with Li, leading a structural deformation that induces disruption. The use of nanostructured silicon materials has been shown to be an effective way to avoid this mechanical degradation of the active material. In this paper the synthesis of silicon nanowires, grown on a highly porous 3D-like carbon paper substrate by CVD using Cu as the catalyst, is presented. The use of carbon paper allows to achieve remarkable loadings of active material (2-5 mg/cm2) and, consequently, high capacity densities. The silicon electrode was investigated both morphologically and electrochemically. To improve the electrochemical performance various strategies have been carried out. It was observed that a very slow first cycle (C/40), which helps the formation of a stable solid electrolyte interphase on the silicon surface, improves the performance of the cells; nevertheless, their cycle life has been found not fully satisfactory. Morphological analysis of the Si-NWs electrodes before and after cycling showed the presence of a dense silicon layer below the nanowires which could reduce the electrical contact between the active material and the substrate
Quantum theory of a polarization phase-gate in an atomic tripod configuration
We present the quantum theory of a polarization phase-gate that can be
realized in a sample of ultracold rubidium atoms driven into a tripod
configuration. The main advantages of this scheme are in its relative
simplicity and inherent symmetry. It is shown that the conditional phase shifts
of order can be attained.Comment: X International Conference on Quantum Optics, Minsk, Belaru
The curve of lines on a prime Fano threefold of genus 8
We show that a general prime Fano threefold X of genus 8 can be reconstructed
from the pair , where is its Fano curve of lines and
is the theta-characteristic which gives a natural embedding
\Gamma \subset \matbb{P}^5.Comment: 24 pages, misprints corrected, to appear in International Journal of
Mathematic
Diabetic striatopathy: an updated overview of current knowledge and future perspectives
Purpose: Diabetic striatopathy (DS) is a rare complication of poorly controlled diabetes mellitus (DM), characterized by hyperglycemia associated with chorea/ballism and characteristic reversible basal ganglia abnormalities on computed tomography (CT) and/or magnetic resonance imaging (MRI). We propose a narrative review of the literature on this topic, currently unknown to most, and about which physicians should be aware. We intend to summarize, critically review, and take to mean the evidence on this disorder, describing its typical features. Methods: We searched Pubmed for English-language sources using the following keywords in the title and the abstract: diabetic striatopathy, hyperglycemic non-ketotic hemichorea/hemiballism, chorea/hemichorea associated with non-ketotic hyperglycemia, diabetic hemiballism/hemichorea, chorea, hyperglycemia, and basal ganglia syndrome. We collected scientific articles, including case reports, reviews, systematic reviews, and meta-analyses from the years 1975 to 2023. We eliminated duplicate, non-English language or non-related articles. Results: Older Asian women are more frequently affected. Suddenly or insidiously hemichorea/hemiballism, mainly in the limbs, and high blood glucose with elevated HbA1c in the absence of ketone bodies have been observed. Furthermore, CT striatal hyperdensity and T1-weighted MRI hyperintensity have been observed. DS is often a treatable disease following proper hydration and insulin administration. Histopathological findings are variable, and no comprehensive hypothesis explains the atypical cases reported. Conclusion: DS is a rare neurological manifestation of DM. If adequately treated, although treatment guidelines are lacking, the prognosis is good and life-threatening complications may occur occasionally. During chorea/hemiballism, we recommend blood glucose and HbA1c evaluation. Further studies are needed to understand the pathogenesis
- …