3,351 research outputs found

    Formal Contexts, Formal Concept Analysis, and Galois Connections

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    Formal concept analysis (FCA) is built on a special type of Galois connections called polarities. We present new results in formal concept analysis and in Galois connections by presenting new Galois connection results and then applying these to formal concept analysis. We also approach FCA from the perspective of collections of formal contexts. Usually, when doing FCA, a formal context is fixed. We are interested in comparing formal contexts and asking what criteria should be used when determining when one formal context is better than another formal context. Interestingly, we address this issue by studying sets of polarities.Comment: In Proceedings Festschrift for Dave Schmidt, arXiv:1309.455

    Using TIRF microscopy to analyze stimulated and basal state B-cell MHC II clustering in response to ageing and dietary fish oil

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    This research focused on developing an efficient TIRF microscopy approach to evaluate membrane protein organization. More specifically, the data demonstrate that TIRF microscopy can detect changes in ex vivo B-cell MHC II lateral organization using a monoclonal antibody under differing conditions. MHC II clustering is dependent on the underlying lipid environment and upon LPS stimulation MHC II expression is dramatically increased. Using mice fed a fish oil or control diet for three weeks, or using mice aged for nine months, we imaged splenic B-cell MHC II clustering using TIRF microscopy. We also used LPS to stimulate B-cells from both experimental conditions to determine if either ageing the animals or feeding them fish oil could affect MHC II clustering. We then determined cluster quantity, size, and intensity using the NIH ImageJ software. The data showed that neither a relevant dose of fish oil, nor aging the mice approximately nine months, had an affect on MHC II clustering in the absence of LPS stimulation. However upon LPS stimulation, MHC II clustering dramatically changed in aged mice as well as fish oil fed mice compared to control animals. Taken together, the data establish the TIRF microscopy protocol as a relevant alternative to more costly and time consuming approaches to address membrane protein clustering. Moreover, either ageing the animals or feeding them fish oil significantly affects MHC II clustering upon stimulation with LPS.  M.S

    Max Dose Opioids: How High Can You Go?

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    Learning Objectives: Describe the rationale for the belief that opioids have no maximum dose Describe the data supporting the rationale that high doses of opioids increase toxicity Describe the data supporting the rationale that high doses of opioids do not improve outcomes Identify potential safety concerns with patients taking high doses of opioid

    Enriched Topology and Asymmetry

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    Mathematically modeling the question of how to satisfactorily compare, in many-valued ways, both bitstrings and the predicates which they might satisfy-a surprisingly intricate question when the conjunction of predicates need not be commutative-applies notions of enriched categories and enriched functors. Particularly relevant is the notion of a set enriched by a po-groupoid, which turns out to be a many-valued preordered set, along with enriched functors extended as to be variable-basis . This positions us to model the above question by constructing the notion of topological systems enriched by many-valued preorders, systems whose associated extent spaces motivate the notion of topological spaces enriched by many-valued preorders, spaces which are non-commutative when the underlying lattice-theoretic base is equipped with a non-commutative (semi-)tensor product. Of special interest are crisp and many-valued specialization preorders generated by many-valued topological spaces, orders having these consequences for many-valued spaces: they characterize the well-established L-T0 separation axiom, define the L-T1(1) separation axiom-logically equivalent under appropriate lattice-theoretic conditions to the L-T1 axiom of T. Kubiak, and define an apparently new L-T1(2) separation axiom. Along with the consequences of such ideas for many-valued spectra, these orders show that asymmetry has a home in many-valued topology comparable in at least some respects to its home in traditional topology

    The relationship between food intake and predation risk in migratory caribou and implications to caribou and wolf population dynamics

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    We examined the hypothesis that spring migration in barren-ground caribou (Rangifer tarandus) enhances access to high quality food, reduces predation risks or both. We related our findings to the hypothesis that one of the consequences of migration is that prey populations cannot be regulated by predation because predators are unable to respond numerically to changes in abundance of migratory prey. In the Northwest Territories, migration to calving grounds by pregnant cows reduced the risk of predation on neonates. Wolf (Canis lupus) densities on calving grounds averaged only 22% of winter range densities because most wolves denned near tree line. The quality and quantity of food that was available to cows that migrated to calving grounds was lower than for bulls and other caribou that lagged far behind the pregnant cows during spring migration. Fecal nitrogen levels were higher in bulls than in cows in late May and early June but there were no differences in mid or late June. Areas occupied by bulls in late May had a greater biomass of live sedges than on the calving ground in early June. It appears that although food in July is abundant and nutritious, insect harassment prevents efficient feeding. Body fat reserves in both sexes declined to almost zero by mid-July, the lowest level of the year. Insect numbers declined in August and body fat levels increased to the highest level of the year by early September. Because the timing of caribou's return to the hunting ranges of tree line denning wolves was related to caribou density, our data were inconsistent with the suggested consequence of migration. Tree line denning by wolves and density-dependent changes in caribou migration suggests a mechanism for population regulation in caribou and wolves. We suggest that the process is as follows; when caribou numbers increase, some density-dependent factor causes range expansion in August (e.g., competition for food) causing caribou to return earlier to the hunting ranges of tree line denning wolves, more denning wolves have access to caribou, wolf pup survival increases and wolf numbers increase. The effect on caribou population growth will depend on the timing and magnitude of the wolf numerical response

    Relationships between Hereditary Sobriety, Sobriety, TD, T1, and Locally Hausdorff

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    This work augments the standard relationships between sobriety, T1, and Hausdorff by mixing in locally Hausdorff and the compound axioms sober + T1 and sober + TD. We show the latter compound condition characterizes hereditary sobriety, and that locally Hausdorff fits strictly between Hausdorff and sober + T1. Classes of examples are constructed, in part to show the non-reversibility of key implications

    Across-Column Cracks and Axial Splits in S2 Saline Ice under Compression

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    Experiments on plate-like specimens have established that across-column cracks from within S2 (columnar) salt-water ice when compressed uniaxially along a direction inclined to the long axis of the grains. Wing cracks initiate from the across-column cracks and lengthen into axial splits when the ice is rapidly deformed; correspondingly; the macroscopic behavior changes from ductile to brittle. The across-column cracking is attributed to grain-boundary sliding, and the splitting to the suppression of crack-tip creep
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