6,259 research outputs found

    Matroids with nine elements

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    We describe the computation of a catalogue containing all matroids with up to nine elements, and present some fundamental data arising from this cataogue. Our computation confirms and extends the results obtained in the 1960s by Blackburn, Crapo and Higgs. The matroids and associated data are stored in an online database, and we give three short examples of the use of this database.Comment: 22 page

    Shock absorbing mount for electrical components

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    A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided

    Major management factors associated with the variation in reproductive performance of Irish dairy herds

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    End of project reportThe results highlight the importance of BCS in achieving good reproductive performance. The likelihood of reproductive success was best predicted by BCS around the time of breeding and, for cows calving in good BCS (3.0 or greater) the level of BCS loss between calving and first service. A low BCS pre-calving (3.5) results in excessive BCS loss (>0.5) post-calving. On the basis of these findings a pre-calving BCS of no greater than 3.25 is a sensible target for pasture-based spring calving systems in Ireland. It is necessary to maintain BCS at 2.75 or greater during the breeding season, and loss of body condition between calving and first service should be restricted to 0.5 BCS units.National Development Plan (NDP

    Maximum size binary matroids with no AG(3,2)-minor are graphic

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    We prove that the maximum size of a simple binary matroid of rank r≥5r \geq 5 with no AG(3,2)-minor is (r+12)\binom{r+1}{2} and characterise those matroids achieving this bound. When r≥6r \geq 6, the graphic matroid M(Kr+1)M(K_{r+1}) is the unique matroid meeting the bound, but there are a handful of smaller examples. In addition, we determine the size function for non-regular simple binary matroids with no AG(3,2)-minor and characterise the matroids of maximum size for each rank

    WATER RIGHTS AND ECOLOGY ON THE WIND RIVER INDIAN RESERVATION: THE COLLISION OF HISTORIES, A TRADITION OF NEGLECT AND SUGGESTIONS FOR RESOLUTION

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    In 1989, in a four-to-four vote without opinion, the United States Supreme Court let stand a senior priority, reserved Indian water right for the Shoshone and Northern Arapaho Tribes of the Wind River Indian Reservation. Shortly thereafter, the Tribes issued a permit requiring a minimum flow of water, known as an \u27instream flow/ on the Wind River for fishery, environmental and cultural purposes. In 1992 however, a Wyoming Supreme Court majority ruled the Tribes must divert their water from its stream channel in order to use it and that the State Engineer shall administer the Tribes\u27 water. Without means to divert, the tribes\u27 water right has essentially been usurped. This Big Horn III case obstructs United States policy of self-determination for Indian tribes and neglects federal principles protecting tribal sovereignty from state interference. The Wyoming court decision also permits irrigators to continue practices that prohibit biological integrity for the Wind River ecosystem and seriously limit cultural, recreational and economic values of the river. Wind River tribal leaders nonetheless opted not to appeal the decision because the U.S. Supreme Court had been acting unpredictably toward Indian rights in lieu of state rights. In the early 1900\u27s, the federal government promised water to both the tribes and non-Indian farmers of the Wind River Basin. Today, mistrust and apprehension surround water use in the basin. Farmers fear their livelihoods could be lost to eventual Indian water use while the tribes watch non-Indians dry up seven miles of river each year by diverting Indian water. Some say that with efficiency, plenty of water exists for both interests. After twenty years and over $20 million, no court or agency has been able to resolve this water rights conflict. It is time for the diverse people of the Wind River to rise above their fears and respect one another in their inherent connection to each other and their river. With mutual respect, the Wind River watershed community can collectively and responsibly manage their water resources in an open, watershed council forum

    Monte Carlo Simulation of Ising Models with Dipole Interaction

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    Recently, a new memory effect was found in the metamagnetic domain structure of the diluted Ising antiferromagnet FexMg1−xCl2Fe_x Mg_{1-x} Cl_2 by domain imaging with Faraday contrast. Essential for this effect is the dipole interaction. We simulate the low temperature behavior of diluted Ising-antiferromagnets by a Monte Carlo simulation considering long range interaction. The metamagnetic domain structure occurring due to the dipole interaction is investigated by graphical representation. In the model considered the antiferromagnetic state is stable for an external magnetic field smaller than a lower boundary Bc1B_{c1} while for fields larger than an upper boundary Bc2B_{c2} the system is in the saturated paramagnetic phase, where the spins are ferromagnetically polarized. For magnetic fields in between these two boundaries a mixed phase occurs consisting of ferromagnetic domains in an antiferromagnetic background. The position of these ferromagnetic domains is stored in the system: after a cycle in which the field is first removed and afterwards applied again the domains reappear at their original positions. The reason for this effect can be found in the frozen antiferromagnetic domain state which occurs after removing the field.Comment: Latex, 10 pages; 3 postsript-figures, compressed tar-file, uuencoded, report 10109

    Correspondence [John F. Dillon]

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