388 research outputs found
Low voltage electron beam bunching and deflection
No full textIn a Malmberg'Penning trap like ELTRAP an electron beam can be stored or propagated in a space charge dominated condition, due to the low acceleration voltage used; in particular we can test the longitudinal expansion of the electron bunch with several diagnostics, including Thomson scattering. Pulsed electron beams produced by an external photocathode source in the 1'10 keV energy range and with 4 ns length have been measured also by two electrostatic diagnostic systems. A proper software is needed to compensate for the capacitance of the pickup electrodes. Rf can be applied to the sectored electrode to produce a plasma source or to excite or to detect rotational modes; in particular the use of a new 8 sector electrode will allow up to m=3 modes
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Adiabatic Focuser
No full textTheoretical analysis is made of an intense relativistic electron beam. such as would be available from a linear collider, moving through a plasma of increasing density, but density always less than that of the beam (underdense). In this situation. the plasma electrons are expelled from the beam channel and the electrons are subject to an ever-increasing focusing force provided by the channel ions. Analysis is made on the beam radiation energy loss in the classical, the transition, and the quantum regimes. It is shown that the focuser is insensitive to the beam energy spread due to radiation loss. Furthermore, because of the different scaling behaviors in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded. The sensitivity of the system to the optic mismatch and the nonlinearity is also analyzed. Examples are given with SLC-type and TLC-type parameters
Neuroreceptors and ion channels as targets of alcohol
No full textThis article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Toshio Narahashi and Kinya Kuriyama. The presentations were (1) Modulation of neuroreceptors and ion channels by alcohol, by T. Narahashi; (2) Inhibition by ethanol of NMDA and AMPA receptor-channels, by P. Illes, K. Wirkner, W. Fischer, K. Muhlberg, P. Scheibler, and C. Allgaier; (3) Effects of ethanol on metabotropic glutamate receptors, by K. Minami; (4) Acute alcohol actions on the 5-HT3 ligand-gated ion channel, by D. Lovinger; (5) Inhibition of NMDA receptors by MK801 attenuates ethanol-induced taurine release from the hippocampus, by F. Lallemand, R.J. Ward, and P. DeWitte; and (6) Effect of ethanol on voltage-operated Ca2+ channels in hepatic stellate cells, by T. Itatsu, Y. Takei, II. Oide, M. Hirose, X. E. Wang, S. Watanabe, M. Tateyama, R. Ochi, and N. Sato
On Principles of Logic
No full textThe author has constructed a subsystem of quantum logic --pseudo-orthomodular logic-- as a sequential logic. It contains Grundsequenz : φ→φ; cut rule : φ→ψ, ψ→χ ⇒ φ→χ; weak thinning rules : →ψ ⇒ φ→ψ and φ→ ⇒ φ→ψ; besides the rules for conjunction and disjunction, weak rules for negation : φ⋀┑φ→ and φ⋀(┑φ⋁ψ)→ ⇒ φ→┑ψ; weak rules for conditional :φ→ψ ⇒ φ⋀(ψ⊃χ)→χ and φ⋀ψ→χ, φⅭψ ⇒ φ→ψ⊃χ. (φⅭψ means "φ is commutable with ψ" , i.e., "φ⋀(┑φ⋁┑ψ)→┑ψ" .) Then this system is an orthomodular subsystem of classical and intuitionistic logics and it can be shown that adding →φ⋁┑φ to it we obtain the system of non-distributive orthomodular quantum logic. (Kagakukisoron-kenkyu, Vo1. 14, No.3, 1980.) It is really remarkable that the system of quantum logic introduces the notion of commutability between sentences and that the conditionalization in the form : φ⋀ψ→χ ⇒ φ→ψ⊃χ is no more valid in quantum logic for non-commutable φ and ψ. This fact obliges us to think the problem "What are principles of logic?" over again, for the conditionalization is a feature of classical logic as well as of intuitionistic logic. In this paper the author examines the Aristotelian doctrine of logic and discusses the problem of logical principles from a modern logical point of view. The main issues are the following. (1) Aristotle has the exact truth-functional notion of logical consequence, that is, he writes several times that we can obtain a true conclusion from a false premise by valid inference. He counts law of contradiction and law of excluded middle among logical principles, which are the most intelligible and the most certain, therefore, he says, we can not demonstrate them from more fundamental laws and all we can do is only to offer the reason (ἔλєγχος) why we accept them. (2) The different properties of classical, intuitionistic and quantum logics draw our attention to the fact that logical principles are concerned with the notion of logical consequence, since all of them play their roles only in the whole system of logic. If the notions of logical consequence are not the same, no more logical sytems are the same, consequently the status of logical principles are different. (3) G. Gentzen, having constructed his system of sequential logic, made the notion of logical consequence clearer than the axiomatic approach does. He distinguishes his sign of sequent '→' from the sign of conditional '⊃' . The former corresponds to 'logical consequence' more subtly than the ordinary axiomatic characterization such as '⊦φ⊃ψ'.This point gets critical, if we take the logical consequence from more than one premises into consideration. Up to the present we have identified 'φ⋀ψ→χ' with 'φ, ψ→χ' and 'φ⋀ψ→χ' with 'φ→ψ⊃χ'. But the system of quantum logic does not allow the identification of 'φ⋀ψ→χ' with 'φ, ψ→χ' , because this assumes the ordinary (strong) left thinning rule. It does not any more permit to infer from 'φ⋀ψ→χ' to 'φ→ψ⊃χ' , because, if we admit this, it follows that the system is distributive. Therefore we must conclude that the choice between the weak left thinning rule and the strong one, together with the notion of commutability, is crucial for the construction of quantum logic. Why cannot we say that the choice of the kind is a logical principle? (4) The law of contradiction of the form : φ⋀┑φ→ is accepted by all classical, intuitionistic and quantum logics. In this sense we can take it for a logical principle and we can say that its status is fairly stable. On the other hand we have the logical systems such as intuitionistic and pseudo-orthomodular logics which do not admit the law of excluded middle. It is difficult to refute the systems of this sort as il-logical, thus the law is not so stable as the law of contradiction. (5) The fundamental question which quantum logic raises is the legality of the notion of commutability. Must we refuse to introduce such a strange notion as 'mutually commutable sentences', but by what reason? The author cannot find any definite reason for the refusal. If we accept the notion, then we will be able to produce a new sort of logic and the notion of logic will change. Therefore we may just as well say that the logical principle, which forms the basis of construction of logical system, has changed. The logical principle is no more so stable nor so certain as Aristotle claimed
Adhesive bonding and corrosion performance investigated as a function of auminum oide chemistry and adhesives
No full textThe long-term strength and durability of an adhesive bond is dependent on the stability of the oxide-adhesive interface. As such, changes in the chemistry of the oxide and/or the adhesive are expected to modify the interfacial properties and affect the joint performance in practice. The upcoming transition to Cr(VI)-free surface pretreatments makes it crucial to evaluate how the incorporation of electrolyte-derived sulfate and phosphate anions from, respectively, phosphoric acid anodizing and sulfuric acid anodizing affect the interfacial chemical properties. Hence, different types of featureless aluminum oxides with well-defined surface chemistries were prepared in this study. The relative amounts of O2−, OH−, , and surface species were quantified using x-ray photoelectron spectroscopy. Next, bonding with two types of commercial aerospace adhesive films was assessed by peel and bondline corrosion tests. The presented results indicate that the durability of the oxide-adhesive interface depends on the interplay between oxide and adhesive chemistries. Epoxy adhesion is highly affected by changes in the oxide surface chemistry, especially the amount of surface hydroxyls. However, the performance of anodic oxides with a lower hydroxyl fraction can be significantly enhanced by the presence of covalent bonds using a silane coupling agent, γ-amino propyl triethoxy. On the contrary, results with Redux 775 adhesive exhibit very low sensitivity to variations in the surface chemistry. Bondline corrosion resistance of the joints is mainly determined by the nature of the adhesive, independent of the varying oxide chemistries.Accepted Author Manuscript(OLD) MSE-6(OLD) MSE-
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