27,917 research outputs found

    Mollusca of the Illinois River, Arkansas

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    The Illinois River is in the Ozark region of northwestern Arkansas and eastern Oklahoma. A survey of the Illinois River in Arkansas produced nine species and one morphological subspecies of gastropods, three species of sphaeriid clams, and 23 species of unionid mussels. Museum records resulted in another two species and an ecophenotype of the Unionidae. This represents the first published survey of molluscan species from the Illinois River in Arkansas

    Dynamical control of quantum state transfer within hybrid open systems

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    We analyze quantum state-transfer optimization within hybrid open systems, from a "noisy" (write-in) qubit to its "quiet" counterpart (storage qubit). Intriguing interplay is revealed between our ability to avoid bath-induced errors that profoundly depend on the bath-memory time and the limitations imposed by leakage out of the operational subspace. Counterintuitively, under no circumstances is the fastest transfer optimal (for a given transfer energy)

    Molecular Gas in the Powerful Radio Galaxies 3C~31 and 3C~264: Major or Minor Mergers?

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    We report the detection of 12^{12}CO~(1→01 \to 0) and 12^{12}CO~(2→12 \to 1) emission from the central regions (≲5\lesssim 5--10kpc10 {\rm kpc}) of the two powerful radio galaxies 3C~31 and 3C~264. Their individual CO emission exhibits a double-horned line profile that is characteristic of an inclined rotating disk with a central depression at the rising part of its rotation curve. The inferred disk or ring distributions of the molecular gas is consistent with the observed presence of dust disks or rings detected optically in the cores of both galaxies. For a CO to H2_2 conversion factor similar to that of our Galaxy, the corresponding total mass in molecular hydrogen gas is (1.3±0.2)×109M⊙(1.3 \pm 0.2) \times 10^9 {\rm M_{\odot}} in 3C~31 and (0.31±0.06)×109M⊙(0.31 \pm 0.06) \times 10^9 {\rm M_{\odot}} in 3C~264. Despite their relatively large molecular-gas masses and other peculiarities, both 3C~31 and 3C~264, as well as many other powerful radio galaxies in the (revised) 3C catalog, are known to lie within the fundamental plane of normal elliptical galaxies. We reason that if their gas originates from the mergers of two gas-rich disk galaxies, as has been invoked to explain the molecular gas in other radio galaxies, then both 3C~31 and 3C~264 must have merged a long time (a few billion years or more) ago but their remnant elliptical galaxies only recently (last tens of millions of years or less) become active in radio. Instead, we argue that the cannibalism of gas-rich galaxies provides a simpler explanation for the origin of molecular gas in the elliptical hosts of radio galaxies. Given the transient nature of their observed disturbances, these galaxies probably become active in radio soon after the accretion event when sufficient molecular gas agglomerates in their nuclei.Comment: 16 pages, 1 JPEG figure attached, accepted for publication in ApJ

    On Steering Swarms

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    The main contribution of this paper is a novel method allowing an external observer/controller to steer and guide swarms of identical and indistinguishable agents, in spite of the agents' lack of information on absolute location and orientation. Importantly, this is done via simple global broadcast signals, based on the observed average swarm location, with no need to send control signals to any specific agent in the swarm

    Dietary modifications for infantile colic

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    Infantile colic can be defined as periods of inconsolable, unexplained, and incessant crying in a seemingly healthy infant that, quite understandably, leads to exhausted, frustrated, and concerned parents seeking to comfort their child (Landgren 2010). The prevalence of excessive crying varies according to the definition used although, most often, it peaks during the second month of life,with a prevalence of 1.5%to 11.9%(Reijneveld 2001).Traditionally, the definition of the condition was based on the rule of three (Wessel 1954): that is, unexplained episodes of paroxysmal crying for more than three hours per day, for three days per week, for at least three weeks. More recently a new definition has been proposed. It refers to a clinical condition of fussing and crying for at least one week in an otherwise healthy infant (Hyman 2006). Colic can be graded as mild, moderate, or severe, though there is no consensus for this classification. Colic can affect up to 10% to 30% of infants worldwide (Clifford 2002; Rosen 2007)

    Effective geometry in Astrophysics

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    The effective metric is introduced by means of two examples (non-linear electromagnetism and hydrodynamics),along with applications in Astrophysics. A sketch of the generality of the effect is also given.Comment: 9 pages, contributions for the proceedings of the First International Workshop on Astronomy and Relativistic Astrophysics (IWARA 2003), Olinda (Brazil

    The Angular Momentum Operator in the Dirac Equation

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    The Dirac equation in spherically symmetric fields is separated in two different tetrad frames. One is the standard cartesian (fixed) frame and the second one is the diagonal (rotating) frame. After separating variables in the Dirac equation in spherical coordinates, and solving the corresponding eingenvalues equations associated with the angular operators, we obtain that the spinor solution in the rotating frame can be expressed in terms of Jacobi polynomials, and it is related to the standard spherical harmonics, which are the basis solution of the angular momentum in the Cartesian tetrad, by a similarity transformation.Comment: 13 pages,CPT-94/P.3027,late

    Finnish Industry Investment ltd: an International Evaluation

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    The Finnish Industry Investment Ltd. (FII) is a government owned investment company, which started its operations in 1995. Its core purpose is to stimulate the development of the Finnish venture capital industry particularly in those areas where market failure has constrained the supply of equity finance to high potential, small and medium sized Finnish enterprises. FII invests in young firms ‘indirectly’ via participating as a cornerstone investor in the new funds of venture capital firms, as well as investing ‘directly’ into Finnish firms. In common with other European venture capital industries, the Finnish industry grew very rapidly between 1995−2000. However, the Finnish market is still very small and under-developed by international standards, particularly, if the high knowledge intensity of the Finnish economy is taken into consideration. The limited availability of early stage (seed and start-up) venture capital to attractive young firms is the most urgent and persistent failure in the Finnish venture capital market. The primary policy goal of FII has been to address this problem by helping to set up, develop, and provide finance to venture capital funds investing in seed and start-up firms. However, FII has also has had a requirement imposed by government to operate profitably. This has lead the organisation to seek later stage investments in order to meet the profitability target. FII’s focus on profitability goal and its practice of investing on equal terms with private investors has lead to a reduction in its effectiveness in resolving the market failure in early stage venture capital. FII’s reduced impact has occurred at a time of worsening market conditions when the need for effective government intervention is highest. The main conclusion of the evaluation is that FII should focus its operations more directly on resolving remaining market failures in the supply of early stage venture capital. The evaluation also argues strongly that FII should concentrate on an indirect operating mode whereby it finances, and incentivizes by asymmetric profit sharing, private investment professionals to set up venture capital funds targeted at seed and startup stages. The same indirect approach should also continue to be used to resolve market failures in the provision of regional venture capital. Additionally, FII has a valuable role in helping channel foreign capital, including finance from EU, to Finnish early stage venture capital funds. Direct investments by FII to target companies should be avoided as an operating mode. Given the FII’s responsibility for addressing market failures, its performance measurement and governance systems should fully reflect this primary goal. The evaluation also finds that FII’s communication and collaboration with other actors in the Finnish innovation system should be improved. In addition to the need for improved coordination between the government special financing agencies, there is also a need for more effective direction and coordination of policy at the highest executive level, for example in ensuring the integration of enterprise policy and general financial policy to enable significant improvements in the environment for growth-oriented entrepreneurship in Finland.Commissioned by Ministry of Trade and Industr

    Generalization properties of finite size polynomial Support Vector Machines

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    The learning properties of finite size polynomial Support Vector Machines are analyzed in the case of realizable classification tasks. The normalization of the high order features acts as a squeezing factor, introducing a strong anisotropy in the patterns distribution in feature space. As a function of the training set size, the corresponding generalization error presents a crossover, more or less abrupt depending on the distribution's anisotropy and on the task to be learned, between a fast-decreasing and a slowly decreasing regime. This behaviour corresponds to the stepwise decrease found by Dietrich et al.[Phys. Rev. Lett. 82 (1999) 2975-2978] in the thermodynamic limit. The theoretical results are in excellent agreement with the numerical simulations.Comment: 12 pages, 7 figure

    Vortex lattice stability and phase coherence in three-dimensional rapidly rotating Bose condensates

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    We establish the general equations of motion for the modes of a vortex lattice in a rapidly rotating Bose-Einstein condensate in three dimensions, taking into account the elastic energy of the lattice and the vortex line bending energy. As in two dimensions, the vortex lattice supports Tkachenko and gapped sound modes. In contrast, in three dimensions the Tkachenko mode frequency at long wavelengths becomes linear in the wavevector for any propagation direction out of the transverse plane. We compute the correlation functions of the vortex displacements and the superfluid order parameter for a homogeneous Bose gas of bounded extent in the axial direction. At zero temperature the vortex displacement correlations are convergent at large separation, but at finite temperatures, they grow with separation. The growth of the vortex displacements should lead to observable melting of vortex lattices at higher temperatures and somewhat lower particle number and faster rotation than in current experiments. At zero temperature a system of large extent in the axial direction maintains long range order-parameter correlations for large separation, but at finite temperatures the correlations decay with separation.Comment: 10 pages, 2 figures, Changes include the addition of the particle density - vortex density coupling and the correct value of the shear modulu
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