302 research outputs found

    Conference on Alaskan placer mining, focus: gold recovery systems

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    Alaska Miners' Association and the School of Mineral Industry, University of Alaska, Fairbanks conference proceedings of the Alaskan Placer Mining conference on Gold Recovery Systems

    Placer mining in Alaska II

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    During July, August and September, 1979, a team from the Mineral Industry Research Laboratory visited a number of placer mining districts that could be reached by automobile, hence at a reasonable cost for transportation. These districts yielded varying amounts of information that will be of value to the industry. The district visited were: 1. Fairbanks, 2. Circle (Birch Creak), 3. Livengood (Tolovana), 4. Manley Hot Springs, 5. Fortymile, 6. Klondike, 7. Kantishna, 8. Yentna.University of Alaska Mining and Mineral Resources Research Institute.Placer mining in Alaska II -- Selected references -- List of figures

    Analytical solution of the Gross-Neveu model at finite density

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    Recent numerical calculations have shown that the ground state of the Gross-Neveu model at finite density is a crystal. Guided by these results, we can now present the analytical solution to this problem in terms of elliptic functions. The scalar potential is the superpotential of the non-relativistic Lame Hamiltonian. This model can also serve as analytically solvable toy model for a relativistic superconductor in the Larkin-Ovchinnikov-Fulde-Ferrell phase.Comment: 5 pages, no figures, revtex; vs2: appendix with analytical proof of self-consistency adde

    Critical and tricritical exponents of the Gross-Neveu model in the large-NfN_f limit

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    The critical and the tricritical exponents of the Gross-Neveu model are calculated in the large-NfN_f limit. Our results indicate that these exponents are given by the mean-field values.Comment: 8 pages, 8 figure

    Revised Phase Diagram of the Gross-Neveu Model

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    We confirm earlier hints that the conventional phase diagram of the discrete chiral Gross-Neveu model in the large N limit is deficient at non-zero chemical potential. We present the corrected phase diagram constructed in mean field theory. It has three different phases, including a kink-antikink crystal phase. All transitions are second order. The driving mechanism for the new structure of baryonic matter in the Gross-Neveu model is an Overhauser type instability with gap formation at the Fermi surface.Comment: Revtex, 12 pages, 15 figures; v2: Axis labelling in Fig. 9 correcte

    Synapse efficiency diverges due to synaptic pruning following over-growth

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    In the development of the brain, it is known that synapses are pruned following over-growth. This pruning following over-growth seems to be a universal phenomenon that occurs in almost all areas -- visual cortex, motor area, association area, and so on. It has been shown numerically that the synapse efficiency is increased by systematic deletion. We discuss the synapse efficiency to evaluate the effect of pruning following over-growth, and analytically show that the synapse efficiency diverges as O(log c) at the limit where connecting rate c is extremely small. Under a fixed synapse number criterion, the optimal connecting rate, which maximize memory performance, exists.Comment: 15 pages, 16 figure

    Z-Score Burden Metric: A Method for Assessing Burden of Injury and Disease

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    Introduction: Traditional methods of summarizing burden of disease have limitations in terms of identifying communities within a population that are in need of prevention and intervention resources. This paper proposes a new method of burden assessment for use in guiding these decisions. Methods: This new method for assessing burden utilizes the sum of population-weighted age-specific z-scores. This new Z-Score Burden Metric was applied to firearm-related deaths in North Carolina counties using 2010‒2017 North Carolina Violent Death Reporting System data. The Z-Score Burden Metric consists of 4 measures describing various aspects of burden. The Z-Score Burden Metric Overall Burden Measure was compared with 2 traditional measures (unadjusted and age-adjusted death rates) for each county to assess similarities and differences in the relative burden of firearm-related death. Results: Of all 100 North Carolina counties, 73 met inclusion criteria (≄5 actual and expected deaths during the study period in each age strata). Ranking by the Overall Burden Measure produced an ordering of counties different from that of ranking by traditional measures. A total of 8 counties (11.0%) differed in burden rank by at least 10% when comparing the Overall Burden Measure with age-adjusted and unadjusted rates. All the counties with large differences between the measures were substantially burdened by firearm-related death. Conclusions: The use of the Z-Score Burden Metric provides an alternative way of measuring realized community burden of injury while still facilitating comparisons between communities with different age distributions. This method can be used for any injury or disease outcome and may help to prioritize the allocation of resources to communities suffering high burdens of injury and disease

    Logarithmic Corrections in the 2D XY Model

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    Using two sets of high-precision Monte Carlo data for the two-dimensional XY model in the Villain formulation on square L×LL \times L lattices, the scaling behavior of the susceptibility χ\chi and correlation length Ο\xi at the Kosterlitz-Thouless phase transition is analyzed with emphasis on multiplicative logarithmic corrections (lnL)−2r(ln L)^{-2r} in the finite-size scaling region and (lnΟ)−2r(ln \xi)^{-2r} in the high-temperature phase near criticality, respectively. By analyzing the susceptibility at criticality on lattices of size up to 5122512^2 we obtain r=−0.0270(10)r = -0.0270(10), in agreement with recent work of Kenna and Irving on the the finite-size scaling of Lee-Yang zeros in the cosine formulation of the XY model. By studying susceptibilities and correlation lengths up to Ο≈140\xi \approx 140 in the high-temperature phase, however, we arrive at quite a different estimate of r=0.0560(17)r = 0.0560(17), which is in good agreement with recent analyses of thermodynamic Monte Carlo data and high-temperature series expansions of the cosine formulation.Comment: 13 pages, LaTeX + 8 postscript figures. See also http://www.cond-mat.physik.uni-mainz.de/~janke/doc/home_janke.htm

    Multigrid Monte Carlo Algorithms for SU(2) Lattice Gauge Theory: Two versus Four Dimensions

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    We study a multigrid method for nonabelian lattice gauge theory, the time slice blocking, in two and four dimensions. For SU(2) gauge fields in two dimensions, critical slowing down is almost completely eliminated by this method. This result is in accordance with theoretical arguments based on the analysis of the scale dependence of acceptance rates for nonlocal Metropolis updates. The generalization of the time slice blocking to SU(2) in four dimensions is investigated analytically and by numerical simulations. Compared to two dimensions, the local disorder in the four dimensional gauge field leads to kinematical problems.Comment: 24 pages, PostScript file (compressed and uuencoded), preprint MS-TPI-94-
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