46,138 research outputs found

    Insects Taken at Japanese Beetle Traps Baited with Anethole-Eugenol in Southern Michigan in 1968

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    A survey of the populations of Jap.anese beetles, Popillia japonica Newman, is made each year in southern Michigan to determine the abundance and distribution of this pest insect. Since little information is available about the insects that are attracted by Japanese beetle attractants in Michigan or anywhere in the United States, a study was made of the insects captured in Japanese beetle traps

    Supernova neutrinos and nucleosynthesis

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    Observations of metal-poor stars indicate that at least two different nucleosynthesis sites contribute to the production of r-process elements. One site is responsible for the production of light r-process elements Z<~50 while the other produces the heavy r-process elements. We have analyzed recent observations of metal-poor stars selecting only stars that are enriched in light r-process elements and poor in heavy r-process elements. We find a strong correlation between the observed abundances of the N=50 elements (Sr, Y and Zr) and Fe. It suggest that neutrino-driven winds from core-collapse supernova are the main site for the production of these elements. We explore this possibility by performing nucleosynthesis calculations based on long term Boltzmann neutrino transport simulations. They are based on an Equation of State that reproduces recent constrains on the nuclear symmetry energy. We predict that the early ejecta is neutron-rich with Ye ~ 0.48, it becomes proton rich around 4 s and reaches Ye = 0.586 at 9 s when our simulation stops. The nucleosynthesis in this model produces elements between Zn and Mo, including 92Mo. The elemental abundances are consistent with the observations of the metal-poor star HD 12263. For the elements between Ge and Mo, we produce mainly the neutron-deficient isotopes. This prediction can be confirmed by observations of isotopic abundances in metal-poor stars. No elements heavier than Mo (Z=42) and no heavy r-process elements are produced in our calculations.Comment: 18 pages, 5 figures, submitted to J. Phys. G: Nucl. Part. Phys. (Focus issue "Nucleosynthesis and the role of neutrinos", ed. Baha Balantekin and Cristina Volpe

    Women and the Revolution in Portugal

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    Fluids with quenched disorder: Scaling of the free energy barrier near critical points

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    In the context of Monte Carlo simulations, the analysis of the probability distribution PL(m)P_L(m) of the order parameter mm, as obtained in simulation boxes of finite linear extension LL, allows for an easy estimation of the location of the critical point and the critical exponents. For Ising-like systems without quenched disorder, PL(m)P_L(m) becomes scale invariant at the critical point, where it assumes a characteristic bimodal shape featuring two overlapping peaks. In particular, the ratio between the value of PL(m)P_L(m) at the peaks (PL,maxP_{L, max}) and the value at the minimum in-between (PL,minP_{L, min}) becomes LL-independent at criticality. However, for Ising-like systems with quenched random fields, we argue that instead ΔFL:=ln(PL,max/PL,min)Lθ\Delta F_L := \ln (P_{L, max} / P_{L, min}) \propto L^\theta should be observed, where θ>0\theta>0 is the "violation of hyperscaling" exponent. Since θ\theta is substantially non-zero, the scaling of ΔFL\Delta F_L with system size should be easily detectable in simulations. For two fluid models with quenched disorder, ΔFL\Delta F_L versus LL was measured, and the expected scaling was confirmed. This provides further evidence that fluids with quenched disorder belong to the universality class of the random-field Ising model.Comment: sent to J. Phys. Cond. Mat

    The Balance of Cultivated Land in China during 1988-1995

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    The extent and fate of cultivated land in China has been the subject of intense debate in academia and the cause for major public concerns in China and abroad. This paper discusses statistics recently compiled by China's State Land Administration on conversions from and to cultivated land. To fit within the LUC research framework, the analysis is mainly presented in terms of eight sub-regions in China which have been defined on the basis of geographic/natural conditions, demographic and economic features, and province-level administrative subdivisions. The eight regions form the geographic building blocks in the LUC economic model. The data compilations reported here provide an improved empirical basis for modeling future land-use changes in China. The analysis concludes that net decreases and abandonment of farmland in China during 1988-1995 amount to 2.2 million hectares, i.e., about 1.6 percent of China's cultivated land base estimated to be 131.1 million hectares at the end of 1995. Net changes in used farmland are the result of reported increases of cultivated land amounting to more than 3 million hectares and, concurrently, farmland conversions and abandonment exceeding 5.2 million hectares during the eight-year period

    An Introduction to Conformal Ricci Flow

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    We introduce a variation of the classical Ricci flow equation that modifies the unit volume constraint of that equation to a scalar curvature constraint. The resulting equations are named the Conformal Ricci Flow Equations because of the role that conformal geometry plays in constraining the scalar curvature. These equations are analogous to the incompressible Navier-Stokes equations of fluid mechanics inasmuch as a conformal pressure arises as a Lagrange multiplier to conformally deform the metric flow so as to maintain the scalar curvature constraint. The equilibrium points are Einstein metrics with a negative Einstein constant and the conformal pressue is shown to be zero at an equilibrium point and strictly positive otherwise. The geometry of the conformal Ricci flow is discussed as well as the remarkable analytic fact that the constraint force does not lose derivatives and thus analytically the conformal Ricci equation is a bounded perturbation of the classical unnormalized Ricci equation. That the constraint force does not lose derivatives is exactly analogous to the fact that the real physical pressure force that occurs in the Navier-Stokes equations is a bounded function of the velocity. Using a nonlinear Trotter product formula, existence and uniqueness of solutions to the conformal Ricci flow equations is proven. Lastly, we discuss potential applications to Perelman's proposed implementation of Hamilton's program to prove Thurston's 3-manifold geometrization conjectures.Comment: 52 pages, 1 figur

    Geometric Laws of Vortex Quantum Tunneling

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    In the semiclassical domain the exponent of vortex quantum tunneling is dominated by a volume which is associated with the path the vortex line traces out during its escape from the metastable well. We explicitly show the influence of geometrical quantities on this volume by describing point vortex motion in the presence of an ellipse. It is argued that for the semiclassical description to hold the introduction of an additional geometric constraint, the distance of closest approach, is required. This constraint implies that the semiclassical description of vortex nucleation by tunneling at a boundary is in general not possible. Geometry dependence of the tunneling volume provides a means to verify experimental observation of vortex quantum tunneling in the superfluid Helium II.Comment: 4 pages, 2 figures, revised version to appear in Phys. Rev.

    Crystalline phases in chiral ferromagnets: Destabilization of helical order

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    In chiral ferromagnets, weak spin-orbit interactions twist the ferromagnetic order into spirals, leading to helical order. We investigate an extended Ginzburg-Landau theory of such systems where the helical order is destabilized in favor of crystalline phases. These crystalline phases are based on periodic arrangements of double-twist cylinders and are strongly reminiscent of blue phases in liquid crystals. We discuss the relevance of such blue phases for the phase diagram of the chiral ferromagnet MnSi.Comment: 6 pages, 5 figures (published version

    Ceramic Experiments At The State Teachers College, Mankato, Minnesota

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    Status of a DEPFET pixel system for the ILC vertex detector

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    We have developed a prototype system for the ILC vertex detector based on DEPFET pixels. The system operates a 128x64 matrix (with ~35x25 square micron large pixels) and uses two dedicated microchips, the SWITCHER II chip for matrix steering and the CURO II chip for readout. The system development has been driven by the final ILC requirements which above all demand a detector thinned to 50 micron and a row wise read out with line rates of 20MHz and more. The targeted noise performance for the DEPFET technology is in the range of ENC=100 e-. The functionality of the system has been demonstrated using different radioactive sources in an energy range from 6 to 40keV. In recent test beam experiments using 6GeV electrons, a signal-to-noise ratio of S/N~120 has been achieved with present sensors being 450 micron thick. For improved DEPFET systems using 50 micron thin sensors in future, a signal-to-noise of 40 is expected.Comment: Invited poster at the International Symposium on the Development of Detectors for Particle, AstroParticle and Synchrotron Radiation Experiments, Stanford CA (SNIC06) 6 pages, 12 eps figure
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