611 research outputs found

    Vegetable Production Guide for Commercial Growers, 2014-15

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    Successful vegetable production generally requires the grower to make daily decisions regarding pest management, irrigation, and cultural practices. Would-be growers unwilling to make serious investments of time (and money) should not attempt to expand beyond a space at the farmers’ market. It is important for vegetable growers to have a market outlet for their product before they choose to start production. Good marketing plans start with the customer and work backward to production. Potential growers should first determine exactly what buyers want, how they want it, and when they want it. They then must determine how these crops should be grown. Even selecting varieties and determining planting times are basic marketing decisions. Kentucky growers should pay particular attention to comparisons of marketing time required, compatibility with off-farm employment, and compatibility with tobacco production. Individual situations vary, and producers often must learn about their particular markets by starting small and getting a foot in the door

    Analytic and Reidemeister torsion for representations in finite type Hilbert modules

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    For a closed Riemannian manifold we extend the definition of analytic and Reidemeister torsion associated to an orthogonal representation of fundamental group on a Hilbert module of finite type over a finite von Neumann algebra. If the representation is of determinant class we prove, generalizing the Cheeger-M\"uller theorem, that the analytic and Reidemeister torsion are equal. In particular, this proves the conjecture that for closed Riemannian manifolds with positive Novikov-Shubin invariants, the L2 analytic and Reidemeister torsions are equal.Comment: 78 pages, AMSTe

    Detailed balance in Horava-Lifshitz gravity

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    We study Horava-Lifshitz gravity in the presence of a scalar field. When the detailed balance condition is implemented, a new term in the gravitational sector is added in order to maintain ultraviolet stability. The four-dimensional theory is of a scalar-tensor type with a positive cosmological constant and gravity is nonminimally coupled with the scalar and its gradient terms. The scalar field has a double-well potential and, if required to play the role of the inflation, can produce a scale-invariant spectrum. The total action is rather complicated and there is no analog of the Einstein frame where Lorentz invariance is recovered in the infrared. For these reasons it may be necessary to abandon detailed balance. We comment on open problems and future directions in anisotropic critical models of gravity.Comment: 10 pages. v2: discussion expanded and improved, section on generalizations added, typos corrected, references added, conclusions unchange

    Elliptic operators on manifolds with singularities and K-homology

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    It is well known that elliptic operators on a smooth compact manifold are classified by K-homology. We prove that a similar classification is also valid for manifolds with simplest singularities: isolated conical points and fibered boundary. The main ingredients of the proof of these results are: an analog of the Atiyah-Singer difference construction in the noncommutative case and an analog of Poincare isomorphism in K-theory for our singular manifolds. As applications we give a formula in topological terms for the obstruction to Fredholm problems on manifolds with singularities and a formula for K-groups of algebras of pseudodifferential operators.Comment: revised version; 25 pages; section with applications expande

    Lifshitz Tails in Constant Magnetic Fields

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    We consider the 2D Landau Hamiltonian HH perturbed by a random alloy-type potential, and investigate the Lifshitz tails, i.e. the asymptotic behavior of the corresponding integrated density of states (IDS) near the edges in the spectrum of HH. If a given edge coincides with a Landau level, we obtain different asymptotic formulae for power-like, exponential sub-Gaussian, and super-Gaussian decay of the one-site potential. If the edge is away from the Landau levels, we impose a rational-flux assumption on the magnetic field, consider compactly supported one-site potentials, and formulate a theorem which is analogous to a result obtained in the case of a vanishing magnetic field

    Eigenvalues of Laplacian with constant magnetic field on non-compact hyperbolic surfaces with finite area

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    We consider a magnetic Laplacian ΔA=(id+A)(id+A)-\Delta_A=(id+A)^\star (id+A) on a noncompact hyperbolic surface \mM with finite area. AA is a real one-form and the magnetic field dAdA is constant in each cusp. When the harmonic component of AA satifies some quantified condition, the spectrum of ΔA-\Delta_A is discrete. In this case we prove that the counting function of the eigenvalues of ΔA-\Delta_{A} satisfies the classical Weyl formula, even when $dA=0.

    Home Vegetable Gardening in Kentucky

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    Before You Begin Every aspiring gardener should follow seven steps to have a successful gardening season: Plan your garden on paper before you begin. Select a good gardening site that is: a. in full sun for at least eight hours each day, b. relatively level, c. well‑drained, d. close to a water source, e. not shaded. Prepare the soil properly and add fertilizer and lime according to soil test recommendations. Plan only as large a garden as you can easily maintain. Beginning gardeners often overplant, and then they fail because they cannot keep up with the tasks required. Weeds and pests must be controlled, water applied when needed and harvesting done on time. Vegetables harvested at their peak are tasty, but when left on the plants too long, the flavor is simply not there. Grow vegetables that will produce the maximum amount of food in the space available. Plant during the correct season for the crop. Choose varieties recommended for your area. Harvest vegetables at their proper stage of maturity. Store them promptly and properly if you do not use them immediately

    On the Usefulness of Modulation Spaces in Deformation Quantization

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    We discuss the relevance to deformation quantization of Feichtinger's modulation spaces, especially of the weighted Sjoestrand classes. These function spaces are good classes of symbols of pseudo-differential operators (observables). They have a widespread use in time-frequency analysis and related topics, but are not very well-known in physics. It turns out that they are particularly well adapted to the study of the Moyal star-product and of the star-exponential.Comment: Submitte

    Quantum Graphs II: Some spectral properties of quantum and combinatorial graphs

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    The paper deals with some spectral properties of (mostly infinite) quantum and combinatorial graphs. Quantum graphs have been intensively studied lately due to their numerous applications to mesoscopic physics, nanotechnology, optics, and other areas. A Schnol type theorem is proven that allows one to detect that a point belongs to the spectrum when a generalized eigenfunction with an subexponential growth integral estimate is available. A theorem on spectral gap opening for ``decorated'' quantum graphs is established (its analog is known for the combinatorial case). It is also shown that if a periodic combinatorial or quantum graph has a point spectrum, it is generated by compactly supported eigenfunctions (``scars'').Comment: 4 eps figures, LATEX file, 21 pages Revised form: a cut-and-paste blooper fixe

    Essential self-adjointness of magnetic Schr\"odinger operators on locally finite graphs

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    We give sufficient conditions for essential self-adjointness of magnetic Schr\"odinger operators on locally finite graphs. Two of the main theorems of the present paper generalize recent results of Torki-Hamza.Comment: 14 pages; The present version differs from the original version as follows: the ordering of presentation has been modified in several places, more details have been provided in several places, some notations have been changed, two examples have been added, and several new references have been inserted. The final version of this preprint will appear in Integral Equations and Operator Theor
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