8,320 research outputs found

    On the relative strengths of fragments of collection

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    Let M\mathbf{M} be the basic set theory that consists of the axioms of extensionality, emptyset, pair, union, powerset, infinity, transitive containment, Δ0\Delta_0-separation and set foundation. This paper studies the relative strength of set theories obtained by adding fragments of the set-theoretic collection scheme to M\mathbf{M}. We focus on two common parameterisations of collection: Πn\Pi_n-collection, which is the usual collection scheme restricted to Πn\Pi_n-formulae, and strong Πn\Pi_n-collection, which is equivalent to Πn\Pi_n-collection plus ÎŁn+1\Sigma_{n+1}-separation. The main result of this paper shows that for all n≄1n \geq 1, (1) M+Πn+1-collection+ÎŁn+2-induction on ω\mathbf{M}+\Pi_{n+1}\textrm{-collection}+\Sigma_{n+2}\textrm{-induction on } \omega proves the consistency of Zermelo Set Theory plus Πn\Pi_{n}-collection, (2) the theory M+Πn+1-collection\mathbf{M}+\Pi_{n+1}\textrm{-collection} is Πn+3\Pi_{n+3}-conservative over the theory M+strong Πn-collection\mathbf{M}+\textrm{strong }\Pi_n \textrm{-collection}. It is also shown that (2) holds for n=0n=0 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 V=LV=L) that does not include the powerset axiom.Comment: 22 page

    Oral Bone Grafting in a Rat Model and the Use of Scanning Electron Microscopy for Tissue Morphology Evaluation

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    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 – 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

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    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

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    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

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    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 drivers’ 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

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    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

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    [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 2.7×10−7% and 5.4×10−5% using the EZAG and ITG generators, respectively
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