3,960 research outputs found
Study made of anodized aluminum circuit boards
Hard coated aluminum circuit boards demonstrate the feasibility of obtaining an electrical power circuit of high packaging density with very high thermal conductivity and mechanical strengths
Information Geometry, Inference Methods and Chaotic Energy Levels Statistics
In this Letter, we propose a novel information-geometric characterization of
chaotic (integrable) energy level statistics of a quantum antiferromagnetic
Ising spin chain in a tilted (transverse) external magnetic field. Finally, we
conjecture our results might find some potential physical applications in
quantum energy level statistics.Comment: 9 pages, added correct journal referenc
Jacobi multipliers, non-local symmetries and nonlinear oscillators
Constants of motion, Lagrangians and Hamiltonians admitted by a family of
relevant nonlinear oscillators are derived using a geometric formalism. The
theory of the Jacobi last multiplier allows us to find Lagrangian descriptions
and constants of the motion. An application of the jet bundle formulation of
symmetries of differential equations is presented in the second part of the
paper. After a short review of the general formalism, the particular case of
non-local symmetries is studied in detail by making use of an extended
formalism. The theory is related to some results previously obtained by
Krasil'shchi, Vinogradov and coworkers. Finally the existence of non-local
symmetries for such two nonlinear oscillators is proved.Comment: 20 page
From Lagrangian to Quantum Mechanics with Symmetries
We present an old and regretfully forgotten method by Jacobi which allows one
to find many Lagrangians of simple classical models and also of nonconservative
systems. We underline that the knowledge of Lie symmetries generates Jacobi
last multipliers and each of the latter yields a Lagrangian. Then it is shown
that Noether's theorem can identify among those Lagrangians the physical
Lagrangian(s) that will successfully lead to quantization. The preservation of
the Noether symmetries as Lie symmetries of the corresponding Schr\"odinger
equation is the key that takes classical mechanics into quantum mechanics.
Some examples are presented.Comment: To appear in: Proceedings of Symmetries in Science XV, Journal of
Physics: Conference Series, (2012
On the solar cycle dependence of winds and planetary waves as seen from mid-latitude D1 LF mesopause region wind measurements
On a generalization of Jacobi's elliptic functions and the Double Sine-Gordon kink chain
A generalization of Jacobi's elliptic functions is introduced as inversions
of hyperelliptic integrals. We discuss the special properties of these
functions, present addition theorems and give a list of indefinite integrals.
As a physical application we show that periodic kink solutions (kink chains) of
the double sine-Gordon model can be described in a canonical form in terms of
generalized Jacobi functions.Comment: 18 pages, 9 figures, 3 table
Online prevention of disordered eating in at-risk young-adult women: A two-country pragmatic randomized controlled trial
This article has been published in a revised form in Psychological Medicine. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. © Cambridge University Press 2017.
This author accepted manuscript is made available following 6 month embargo from date of publication (Dec 2017) in accordance with the publisher’s copyright policyDisordered eating (DE) is a widespread, serious problem. Efficacious prevention programs that can be delivered at-scale are needed.
A pragmatic randomized controlled trial of two online programs was conducted. Participants were young-adult women from Australia and New Zealand seeking to improve their body image. Media Smart-Targeted (MS-T) and Student Bodies (SB) were both 9-module interventions released weekly, whilst control participants received positive body image information. Primary [Eating Disorder Examination–Questionnaire (EDE-Q) Global], secondary (DE risk factors) and tertiary (DE) outcome measures were completed at baseline, post-program, 6- and 12-month follow-up.
Baseline was completed by 608 women (M age = 20.71 years); 33 were excluded leaving 575 randomized to: MS-T (N = 191); SB (N = 190) or control (N = 194). Only 66% of those randomized to MS-T or SB accessed the intervention and were included in analyses with controls; 78% of this sample completed measures subsequent to baseline. Primary intent-to-treat (ITT) analyses revealed no differences between groups, while measure completer analyses found MS-T had significantly lower EDE-Q Global than controls at 12-month follow-up. Secondary ITT analyses found MS-T participants reported significantly higher quality of life–mental relative to both SB and controls (6-month follow-up), while MS-T and controls had lower clinical impairment relative to SB (post-program). Amongst measure completers, MS-T scored significantly lower than controls and SB on 5 variables. Of those with baseline DE, MS-T participants were significantly less likely than controls to have DE at 12-month follow-up.
Given both programs were not therapist-moderated, MS-T has potential to achieve reductions in DE risk at low implementation costs
Analysing the sensitivity of Arctic large-scale circulation to the regional radiation forcing over Europe using deep learning
The Arctic large-scale circulation is governed by a wide range of factor. In order to investigate the sensitivity of the Arctic large-scale circulation to the regional radiative forcing over Europe, we conducted sensitivity experiments using a state-of-the-art atmosphere-land-ocean coupled model. Using advanced Deep Learning (DL) algorithms, we analyzed the Arctic circulation regimes response to negative radiative forcing anomalies over Europe. We examined different architectures for our DL algorithm to find the most suitable one for our analysis. We simultaneously layer Thickness (300-700-T) and their spatiotemporal patterns with the DL algorithm. The DL algorithm showed good skills in capturing the general structure of the large-scale circulation. The radiative forcing over Europe doesn't seem to induce the occurrence frequency of preferred circulation regimes.Die arktische großräumige Zirkulation wird von einer Vielzahl von Faktoren bestimmt. Um die Sensitivität der arktischen großräumigen Zirkulation auf den regionalen Strahlungsantrieb über Europa zu untersuchen, haben wir Sensitivitätsexperimente mit einem hochmodernen gekoppelten Atmosphäre-Land-Ozean-Modell untersucht. Unter Verwendung neuer Deep-Learning-Algorithmen (DL) analysierten wir die Reaktion der arktischen Zirkulationsregime auf negativen Strahlungsantriebsanomalien über Europa. Wir haben verhsciedene Architekturen für unseren DL-Algorithmus untersucht, um die am besten geeignete für unsere Analyse zu finden. Wir haben die Felder des mittleren Drucks auf Meeresspiegelniveau und der Schichtdicke von 700 bis 300 hPa und ihre raumzeitlichen Muster mit dem DL-Algorithmus analysiert. Die DL-Algorithmen zeigten gute Ergebnisse bei der Erfassung der allgmeinen Struktur der großräumigen Zirkulation. Der Strahlungsantrieb über Europa scheint der großräumigen Zirkulation keine neuen raumzeitlichen Muster zuzufügen, veränderte aber die Häufigkeit des Auftretens bevorzugter Zirkulationsmuster
Distortion of meteor count rates due to cosmic radio noise and atmospheric particularities
The determination of the meteoroid flux is still a scientifically challenging
task. This paper focusses on the impact of extraterrestrial noise sources as
well as atmospheric phenomena on the observation of specular meteor echoes.
The effect of cosmic radio noise on the meteor detection process is estimated
by computing the relative difference between radio loud and radio quiet areas
and comparing the monthly averaged meteor flux for fixed signal-to-noise
ratios or fixed electron line density measurements. Related to the cosmic
radio noise is the influence of D-layer absorption or interference with
sporadic E-layers, which can lead to apparent day-to-day variation of the
meteor flux of 15–20%
Elliptic Phases: A Study of the Nonlinear Elasticity of Twist-Grain Boundaries
We develop an explicit and tractable representation of a twist-grain-boundary
phase of a smectic A liquid crystal. This allows us to calculate the
interaction energy between grain boundaries and the relative contributions from
the bending and compression deformations. We discuss the special stability of
the 90 degree grain boundaries and discuss the relation of this structure to
the Schwarz D surface.Comment: 4 pages, 2 figure
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