8,320 research outputs found
On the relative strengths of fragments of collection
Let be the basic set theory that consists of the axioms of
extensionality, emptyset, pair, union, powerset, infinity, transitive
containment, -separation and set foundation. This paper studies the
relative strength of set theories obtained by adding fragments of the
set-theoretic collection scheme to . We focus on two common
parameterisations of collection: -collection, which is the usual
collection scheme restricted to -formulae, and strong
-collection, which is equivalent to -collection plus
-separation. The main result of this paper shows that for all ,
(1) proves the consistency of Zermelo Set Theory plus
-collection,
(2) the theory is
-conservative over the theory .
It is also shown that (2) holds for when the Axiom of Choice is
included in the base theory. The final section indicates how the proofs of (1)
and (2) can be modified to obtain analogues of these results for theories
obtained by adding fragments of collection to a base theory (Kripke-Platek Set
Theory with Infinity and ) that does not include the powerset axiom.Comment: 22 page
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The Rumsfeld Effect: The unknown unknown
A set of studies tested whether people can use awareness of ignorance to provide enhanced test consistency over time if they are allowed to place uncertain items into a âdonât knowâ category. For factual knowledge this did occur, but for a range of other forms of knowledge relating to conceptual knowledge and personal identity, no such effect was seen. Known unknowns would appear to be largely restricted to factual kinds of knowledge
Oral Bone Grafting in a Rat Model and the Use of Scanning Electron Microscopy for Tissue Morphology Evaluation
Oral bone grafting is a procedure widely performed in current dentistry. Several biomaterials fit this purpose. The aim of this study was to use scanning electron microscopy (SEM) to evaluate the ultrastructural aspects of bone repair in a rat model, with periodontal tissues involved. Two groups (I and II) of 20 animals each were operated on to create a surgical defect with a round carbide burr (3mm) on the right side of their mandible, anterior to the mental foramen. Both groups were evenly divided with 5 animals each to receive the application of either bifasic calcium phosphate bioceramic (B), lyophilized deproteinated bovine bone (L), bifasic bioceramic associated with lyophilized deproteinated bovine bone (BL), or no biomaterial (control or C). Group I was monitored for one week and group II for three weeks prior to euthanasia. Hemi-mandibles were prepared for SEM analysis. Parameters such as exposure of incisive root surface, width of the cross-section of filiform structures and presence of mineralized-like globuli (area) were evaluated. The findings of this study suggested that surgical procedures for introduction or not of biomaterial did not cause problems with normal feeding to the animals. Both of the biomaterials used promoted a periodontal ligament involvement. Fibers (single filiform structures) could be detected in a range from 0.07 to 0.18ÎŒm of diameter, except for L that was larger â considered to be due to residual fibers of bovine origin. C bundles (groups of fibers) showed larger width of cross-section than with the use of biomaterials. Globuli areas (mineralization) were smaller to C than with the biomaterials use. B showed larger globuli areas, suggesting slow incorporation. It was concluded that the use of these biomaterials favored maintenance of tissue volume although slowing remodeling, and the combination (BL) presented the best performance.
Solid-state magnetic traps and lattices
We propose and analyze magnetic traps and lattices for electrons in
semiconductors. We provide a general theoretical framework and show that
thermally stable traps can be generated by magnetically driving the particle's
internal spin transition, akin to optical dipole traps for ultra-cold atoms.
Next we discuss in detail periodic arrays of magnetic traps, i.e. magnetic
lattices, as a platform for quantum simulation of exotic Hubbard models, with
lattice parameters that can be tuned in real time. Our scheme can be readily
implemented in state-of-the-art experiments, as we particularize for two
specific setups, one based on a superconducting circuit and another one based
on surface acoustic waves.Comment: 18 pages, 8 figure
Noise and thermal stability of vibrating micro-gyrometers preamplifiers
The preamplifier is a critical component of gyrometer's electronics. Indeed
the resolution of the sensor is limited by its signal to noise ratio, and the
gyrometer's thermal stability is limited by its gain drift. In this paper, five
different kinds of preamplifiers are presented and compared. Finally, the
design of an integrated preamplifier is shown in order to increase the gain
stability while reducing its noise and size.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Self-regulation of driving and its relationship to driving ability among older adults
Although it is known that older drivers limit their driving, it is not known whether this self-regulation is related to actual driving ability. A sample of 104 older drivers, aged between 60 and 92, completed a questionnaire about driving habits and attitudes. Ninety of these drivers also completed a structured on-road driving test. A measure of self-regulation was derived from driversâ self-reported avoidance of difficult driving situations. The on-road driving test involved a standard assessment used to determine fitness to drive. Of the 90 participants who completed the driving assessment, 68 passed the test, eight passed but were recommended to have driving lessons and 14 failed. Driving test scores for the study were based on the number of errors committed in the driving tests, with weightings given according to the seriousness of the errors. The most commonly avoided difficult driving situations were parallel parking and driving at night in the rain, while the least avoided situation was driving alone. Poorer performance on the driving test was not strongly related to overall avoidance of difficult driving situations. Stronger relationships were found between driving ability and avoidance of specific difficult driving situations. These specific driving situations were the ones in which the drivers had low confidence and that the drivers were most able to avoid if they wished to. These results may reflect a tendency for those with poorer driving ability to lose confidence in their driving, and begin to avoid difficult driving situations. However, there are a number of situations that drivers find difficult to avoid.M.R.J. Baldock, J.L. Mathias, A.J. McLean, A. Bernd
The Vincia Parton Shower
We summarize recent developments in the VINCIA parton shower. After a brief
review of the basics of the formalism, the extension of VINCIA to hadron
collisions is sketched. We then turn to improvements of the efficiency of
tree-level matching by making the shower history unique and by incorporating
identified helicities. We conclude with an overview of matching to one-loop
matrix elements.Comment: 6 pages, to appear in the proceedings of DIS 201
Experience in Production of 68Ga-DOTA-NOC for Clinical Use Under an Expanded Access IND
[68Ga]Ga-DOTA-NOC was produced under an Expanded Access IND for 174 clinical PET/CT studies to evaluate patients with neuroendocrine tumors. Production employed either the TiO2-based Eckert & Ziegler (EZAG) 68Ge/68Ga-generator (with fractionated elution), or the SiO2-based ITG 68Ge/68Ga-generator. In both cases, [68Ga]Ga-DOTA-NOC was reliably produced, without pre-synthesis purification of the68Ga generator eluate, using readily-implemented manual synthesis procedures. [68Ga]Ga-DOTA-NOC radiochemical purity averaged 99.2±0.4%. Administered 68Ga dose averaged 181±22 MBq, and administered peptide mass averaged 43.2±5.2 ”g (n=47) and 23.9±5.7 ”g (n=127), respectively, using the EZAG and ITG generators. At dose expiration, 68Ge breakthrough in the final product averaged 2.7Ă10â7% and 5.4Ă10â5% using the EZAG and ITG generators, respectively
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