46,530 research outputs found

    Fractal templates in the escape dynamics of trapped ultracold atoms

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    We consider the dynamic escape of a small packet of ultracold atoms launched from within an optical dipole trap. Based on a theoretical analysis of the underlying nonlinear dynamics, we predict that fractal behavior can be seen in the escape data. This data would be collected by measuring the time-dependent escape rate for packets launched over a range of angles. This fractal pattern is particularly well resolved below the Bose-Einstein transition temperature--a direct result of the extreme phase space localization of the condensate. We predict that several self-similar layers of this novel fractal should be measurable and we explain how this fractal pattern can be predicted and analyzed with recently developed techniques in symbolic dynamics.Comment: 11 pages with 5 figure

    Zero-loss/deflection map analysis

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    Experimental plots of the fraction of detected electrons removed from the zero-loss peak, versus the fraction of incident electrons scattered outside of the objective aperture, can serve as a robust fingerprint of object-contrast in an energy filtered transmission electron microscope (EFTEM). Examples of this, along with the first in a series of models for interpreting the resulting patterns, were presented at the August 2010 meeting of the Microscope Society of America meeting in Portland, Oregon, and published in {\em Microscopy and MicroAnalysis} {\bf 16}, Supplement 2, pages 1534-1535 by Cambridge University Press.Comment: 3 pages (3 figs, 4 refs) RevTeX, cf. http://www.umsl.edu/~fraundorfp/zldeflmaps.htm

    Economic Impact Assessment: the creative sector in the Western Region

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    Introduction. Developments around the globe are re-defining media, arts and other related sectors as ‘creative industries’ which are being recognised for their potential impact on local and national economies. This economic impact assessment builds on previous work commissioned by the Western Development Commission and contends that artistic and cultural activities are not simple by-products of a developed economy but essential elements of economic success and sustainability. Such activities represent alternate forms of expression of human creativity that encourage lateral thinking and thus complement scientific and technological innovation. As we will see, these activities lie at the core of a number of growing sectors in the region, and contribute directly to employment growth and wealth creation2. Internationally, the case for fostering the creative economy is a convincing one. In the ten years up to 2005, the creative economy grew at twice the annual rate of the service industries and four times the rate of manufacturing in OECD countries3. In Europe, the growth of the cultural and creative sector was 12.3% higher than the growth of the overall economy from 1999 to 2003. From an economic perspective, international trade is a key component, from 2000 – 2005, trade in creative-industry products grew on average by 8.7% annually. These figures have grabbed the attention of policy makers here and abroad. This report was commissioned by the Western Development Commission (WDC) in July 2010 to consider the economic impact of the Creative Economy in the Western Region of Ireland4. It builds on previous work carried out by Oxford Economics and the WDC. That work, published as the Creative West document in early 2009 informed a great deal of debate at the regional and national level. This work attempts to add a dynamic element to what was a snapshot of the sector

    Derivation of the Gauge Link in Light Cone Gauge

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    In light cone gauge, a gauge link at light cone infinity is necessary for transverse momentum-dependent parton distribution to restore the gauge invariance in some specific boundary conditions. We derive such transverse gauge link in a more regular and general method. We find the gauge link at light cone infinity naturally arises from the contribution of the pinched poles: one is from the quark propagator and the other is hidden in the gauge vector field in light cone gauge. Actually, in the amplitude level, we have obtained a more general gauge link over the hypersurface at light cone infinity which is beyond the transverse direction. The difference of such gauge link between semi-inclusive deep inelastic scattering and Drell-Yan processes can also be obtained directly and clearly in our derivation.Comment: 18 pages, 5 figures, published versio

    An evaluation of the suitability of ERTS data for the purposes of petroleum exploration

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    This experiment was designed to determine the types and amounts of information valuable to petroleum exploration extractable from ERTS data and the cost of obtaining the information using traditional or conventional means. It was desired that an evaluation of this new petroleum exploration tool be made in a geologically well known area in order to assess its usefulness in an unknown area. The Anadarko Basin lies in western Oklahoma and the panhandle of Texas. It was chosen as a test site because there is a great deal of published information available on the surface and subsurface geology of the area, and there are many known structures that act as traps for hydrocarbons. This basin is similar to several other large epicontinental sedimentary basins. It was found that ERTS imagery is an excellent tool for reconnaissance exploration of large sedimentary basins or new exploration provinces. For the first time, small and medium size oil companies can rapidly and effectively analyze exploration provinces as a whole

    Programmable networks for quantum algorithms

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    The implementation of a quantum computer requires the realization of a large number of N-qubit unitary operations which represent the possible oracles or which are part of the quantum algorithm. Until now there are no standard ways to uniformly generate whole classes of N-qubit gates. We have developed a method to generate arbitrary controlled phase shift operations with a single network of one-qubit and two-qubit operations. This kind of network can be adapted to various physical implementations of quantum computing and is suitable to realize the Deutsch-Jozsa algorithm as well as Grover's search algorithm.Comment: 4 pages. Accepted version; Journal-ref. adde

    The Transversity Function and Double Spin Azimuthal Asymmetry in Semi-Inclusive Pion Leptoproduction

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    We show that the transverse momentum dependent transversity function is proportional to the longitudinal polarization of a quark in a transversely polarized proton. This result suggests an alternative, convenient method for determining transversity, without knowing unusual fragmentation functions. The method consists of measuring the double spin azimuthal asymmetry in semi-inclusive pion leptoproduction by a transversely polarized proton target. The asymmetry, which is twist 3, is estimated to be more than 10% under the most favorable conditions. The experiment we suggest is feasible at facilities like DESY and CERN.Comment: extended version; to appear on Int. Jou. Mod. Phys.

    Non-Markovian Stochastic Resonance

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    The phenomenological linear response theory of non-Markovian Stochastic Resonance (SR) is put forward for stationary two-state renewal processes. In terms of a derivation of a non-Markov regression theorem we evaluate the characteristic SR-quantifiers; i.e. the spectral power amplification (SPA) and the signal-to-noise ratio (SNR), respectively. In clear contrast to Markovian SR, a characteristic benchmark of genuine non-Markovian SR is its distinctive dependence of the SPA and SNR on small (adiabatic) driving frequencies; particularly, the adiabatic SNR becomes strongly suppressed over its Markovian counterpart. This non-Markovian SR theory is elucidated for a fractal gating dynamics of a potassium ion channel possessing an infinite variance of closed sojourn times.Comment: 4 pages, 1 figur
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