37,109 research outputs found
Pcf theory and cardinal invariants of the reals
The additivity spectrum ADD(I) of an ideal I is the set of all regular
cardinals kappa such that there is an increasing chain {A_alpha:alpha<kappa\}
in the ideal I such that the union of the chain is not in I.
We investigate which set A of regular cardinals can be the additivity
spectrum of certain ideals.
Assume that I=B or I=N, where B denotes the sigma-ideal generated by the
compact subsets of the Baire space omega^omega, and N is the ideal of the null
sets.
For countable sets we give a full characterization of the additivity spectrum
of I: a non-empty countable set A of uncountable regular cardinals can be
ADD(I) in some c.c.c generic extension iff A=pcf(A).Comment: 9 page
Repository Steering Groups
A well-chosen, well-informed and committed Steering
Group can make an important contribution to the
sustained success of a repository. This Briefing Paper
highlights some of the issues for consideration when
planning the role, remit and composition of a repository
Steering Group
Recommended from our members
Anti-social behaviour orders: an infringement of the Human Rights Act 1998?
Fabrication and repair of graphite/epoxy laminates
New forming and patching methods have been developed for high-quality graphite/epoxy laminates. Laminates range in thickness from 0.012 to 0.018 in. (0.31 to 0.46 mm)
Fluorine negative ion detachment kinetics
A study of the rate of F(-) detachment by O and H atoms via the reactions F(-) + O yields FO + e and F(-) + H yields FH+ e was undertaken using a drift tube to produce F(-) ions at various drift velocities and therefore different ion temperatures. Preliminary mobility measurements of F(-) ions in Ar were made, indicating that ion temperatures in the 300 K to 5000 K range could be achieved; however due to numerous difficulties experienced in obtaining a reliable F(-) ion source, the study could not be completed
Microdosimetric concepts relevant to HZE-particles
The biological effectiveness of HZE-particles
i s determined by the extreme microscopic concentrations
of energy transfer in the vicinity
of the particle tracks. The concept of linear
energy transfer fails to describe this situation
adequately. The more rigorous microdosimetric
concepts are presented. A simplified
treatment, based on the radial distribution
of energy around the track core, is then considered
Revision of the weevil genus Epimechus Dietz (Coleoptera: Curculionidae: Anthonomini)
Epimechus curvipes Dietz is designated as type species of the genus Epimechus Dietz. Ten additional species from western North America, including four new species, are assigned to the genus: E. aemulus Fall; E. flavirostris Fall; E. mimicus Dietz; E. adspersus Dietz; E. mobilis Fall; E. nevadicus Dietz; E. molina, new species (Arizona, Baja California Norte); E. combustus, new species (Arizona, New Mexico, Utah); E. signum, new species (Arizona, Coahuila, Colorado, New Mexico, Saskatchewan, Texas, Utah) and E. hesperius, new species (Arizona, California, Colorado, Guanajuato, Idaho, Nevada, New Mexico, Nuevo Leon, South Dakota, Texas, Utah, Wyoming). These are distinguished from other Anthonomini by the short, simple tarsal claws. The names Epimeclws modicus Fall, E. soriculus Dietz, and E. nanulus Fall are placed in new synonymy under E. curvipes. Lectotypes are designated for E. adspersus and E. nevadicus. Two species formerly in Epimechus are transferred the subgenus Cnemocyllus Dietz in Anthonomus Germar: E. arenicolor Fall as Anthonomus arenicolor (Fall), new combination, and E. canoides Fall as Anthonomus canoides (Fall), new combination. Adults of species of Epimechus have been collected on plants in the genera Baccharis, Chrysothamnus, Ericameria, Gutierrezia, Haplopappus, Senecio and Tetradymia (all Asteraceae)
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