8,921 research outputs found

    The ontology of causal process theories

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    There is a widespread belief that the so-called process theories of causation developed by Wesley Salmon and Phil Dowe have given us an original account of what causation really is. In this paper, I show that this is a misconception. The notion of "causal process" does not offer us a new ontological account of causation. I make this argument by explicating the implicit ontological commitments in Salmon and Dowe's theories. From this, it is clear that Salmon's Mark Transmission Theory collapses to a counterfactual theory of causation, while the Conserved Quantity Theory collapses to David Fair's phsyicalist reduction of causation

    Intermediate range chemical ordering of cations in simple molten alkali halides

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    The presence of first sharp diffraction peaks in the partial structure factors is investigated in computer simulations of molten mixtures of alkali halides. An intermediate range ordering appears for the Li+ ions only, which is associated with clustering of this species and is not reflected in the arrangement of other ions. This ordering is surprising in view of the simplicity of the interionic interactions in alkali halides. The clustering reflects an incomplete mixing of the various species on a local length scale, which can be demonstrated by studying the complementary sub-space of cations in the corresponding pure alkali halides by means of a void analysis.Comment: 5 pages, 5 figure

    WILDLIFE DAMAGE IN AUSTRALIA: CONSTRUCTIVE CONTRASTS WITH THE UNITED STATES

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    There are numerous wildlife damage problems in Australia. The major pests include rabbits (Oryctolagus cuniculusl, foxes (Vulpes vulpes/, starlings (Sturnus vulgarisl, feral cats (felts catus/, donkeys (Equus asinusl, goats (Capra hircusl, buffalo (Bubalus trutralisl, pigs (Sus scrofal, all of which have been introduced. The dingo ICanis familiaris dingo/, classified as being a native species by most people, is the primary native animal causing problems, although others, such as kangaroos and several native bird species, are pests in some areas. The Australians spend considerable amounts of money on wildlife damage control research. The people of Western Australia take a regulatory approach to most of their wildlife problems. The concept of declaring species as pests allows the Australians to regulate what can and should be done to control these species. Australian wildlife control programs range from conducting control activities to simply advising as to what should be done. The Australians often designate areas where control should (or should not) be undertaken. This approach allows clear decisions to be made about control program expenditures and resource deployment

    Differential effects of Alzheimer\u27s disease and Huntington\u27s disease on the performance of mental rotation

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    he ability to spatially rotate a mental image was compared in patients with Alzheimer\u27s disease (AD; n = 18) and patients with Huntington\u27s disease (HD; n = 18). Compared to their respective age-matched normal control (NC) group, the speed, but not the accuracy, of mental rotation abnormally decreased with increasing angle of orientation for patients with HD. In contrast, the accuracy, but not the speed, of rotation abnormally decreased with increasing angle of orientation for patients with AD. Additional analyses showed that these unique patterns of performance were not attributable to different speed/accuracy trade-off sensitivities. This double dissociation suggests that the distinct brain regions affected in the two diseases differentially contribute to speed and accuracy of mental rotation. Specifically, the slowing exhibited by HD patients may be mediated by damage to the basal ganglia, whereas the spatial manipulation deficit of AD patients may reflect pathology in parietal and temporal lobe association cortices important for visuospatial processing. (JINS, 2005, 11, 30–39.

    A randomized controlled trial of PEEK versus titanium interference screws for anterior cruciate ligament reconstruction with 2-year follow-up

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    Purpose: To compare the clinical performance of ACL reconstruction with PEEK and titanium interference screws at 2 years and to evaluate a novel method of measuring tunnel volume. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 133 patients underwent arthroscopic ACL reconstruction with 4-strand hamstring autografts and were randomized to have titanium or PEEK interference screws for femoral and tibial tunnel fixation. At 2 years, subjective Lysholm and International Knee Documentation Committee scores were assessed and clinical examination performed. At 12 months, MRI was performed to assess graft incorporation and cyst formation, and a novel technique was employed to measure tunnel volumes. Results: There were no significant differences in graft rerupture rate, contralateral ACL rupture rate, subjective outcomes, or objective outcomes. In the titanium and PEEK groups, MRI demonstrated high overall rates of graft integration (96%-100% and 90%-93%, respectively) and ligamentization (89% and 84%) and low rates of synovitis (22% and 10%) and cyst formation (0%-18% and 13%-15%). There was a higher proportion of patients with incomplete graft integration within the femoral tunnel in the PEEK group as compared with the titanium group (10% vs 0%, P = .03); however, the authors suggest that metal artifact precluded proper assessment of the graft in the titanium group by MRI. Tunnel volumes also appeared to be equivalent in the 2 groups and were measured with a novel technique that was highly reproducible in the PEEK group secondary to the absence of flare. Conclusion: Two-year clinical analysis of PEEK interference screws for femoral and tibial fixation of ACL reconstructions showed equivalent clinical performance to titanium interference screws. Given the excellent mechanical characteristics, biological compatibility, and absence of metal artifact on MRI, PEEK has become our material of choice for interference screw fixation in ACL reconstruction

    Slow flows of an relativistic perfect fluid in a static gravitational field

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    Relativistic hydrodynamics of an isentropic fluid in a gravitational field is considered as the particular example from the family of Lagrangian hydrodynamic-type systems which possess an infinite set of integrals of motion due to the symmetry of Lagrangian with respect to relabeling of fluid particle labels. Flows with fixed topology of the vorticity are investigated in quasi-static regime, when deviations of the space-time metric and the density of fluid from the corresponding equilibrium configuration are negligibly small. On the base of the variational principle for frozen-in vortex lines dynamics, the equation of motion for a thin relativistic vortex filament is derived in the local induction approximation.Comment: 4 pages, revtex, no figur

    Speech of Hon. Salmon P. Chase.

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    Speech of Honorary Salmon P. Chase delivered at the Republican Mass Meeting in Cincinnati, August 21, 1855. Together with extracts from his speeches in the Senate of Kindred subjects. Consisting of 16 pages.https://stars.library.ucf.edu/civilwar-text/1023/thumbnail.jp

    Letter, Salmon P. Chase to Elliot C. Cowden, September 2, 1862

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    This handwritten letter, dated September 8, 1862, is from Salmon P. Chase to Elliot C. Cowden as a response to Cowden\u27s letter to Chase on September 2. Chase informs Cowden that Mr. John Mack\u27s appointment was made by the President on the recommendation of some of the best the citizens of New York and is not under the purview of the Secretary of the Treasury. Chase goes on to encourage that perhaps experience will prove the selection not so injudicious as you think it now. A Treasury Department envelope postmarked Washington, D. C. Sep. 9, 1862 and addressed to Elliot C. Cowdin, Esq. in New York is included with the letter.https://scholarsjunction.msstate.edu/fvw-manuscripts-original-manuscripts/1130/thumbnail.jp

    Letter, Salmon P. Chase to Thomas Bolton, October 14, 1848

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    This handwritten letter, dated October 14, 1848, is written from Salmon P. Chase to Thomas Bolton wherein Chase discusses the difficulties in getting a letter two Van Buren [Martin VanBuren?] and the difficulty of planning for VanBuren\u27s impending visit.https://scholarsjunction.msstate.edu/fvw-manuscripts-original-manuscripts/1123/thumbnail.jp
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