Search results for " ring"
showing 10 items of 478 documents
Noetherian type in topological products
2010
The cardinal invariant "Noetherian type" of a topological space $X$ (Nt(X)) was introduced by Peregudov in 1997 to deal with base properties that were studied by the Russian School as early as 1976. We study its behavior in products and box-products of topological spaces. We prove in Section 2: 1) There are spaces $X$ and $Y$ such that $Nt(X \times Y) < \min\{Nt(X), Nt(Y)\}$. 2) In several classes of compact spaces, the Noetherian type is preserved by the operations of forming a square and of passing to a dense subspace. The Noetherian type of the Cantor Cube of weight $\aleph_\omega$ with the countable box topology, $(2^{\aleph_\omega})_\delta$, is shown in Section 3 to be closely related …
A topological model for Oersted-Amp�re's law
1973
A geometrical description of Oersted-Ampere's law ∮H ds=(4π/c)I can be given in terms of an appropriate topological manifold. More precisely: It will be shown that Oersted-Ampere's law can be related to the topological invariantH 1(S 1), i.e. de Rham's first cohomology group on the differentiable manifoldS 1={(x,y) ∈ ℝ2∶x 2+y 2}
Whispering gallery mode resonator sensors referenced to saturated absorption lines in rubidium atoms and a fs frequency comb
2019
Optical Whispering Gallery Mode Resonators (WGMR) can be produced by many methods, for example, by flame melting of silica fibers [1], by polishing of crystals [2], by optical lithography, by solidifying transparent materials, or using commercially available microspheres. They confine light by the total internal reflection and do not need mirror coatings. A part of radiation is traveling outside the WGMR as an evanescent wave and it is used for sensing applications. WGMRs are becoming increasingly popular as biosensors [3] when their surface is covered with antibodies to provide selectivity. Advantage is that light circulates in the resonator and interacts many times with a few molecules at…
Synthetic and theoretical studies of novel ring closure and ring opening reactions
2006
Ring closure and ring opening reactions are in many cases useful synthetic procedures in organic chemistry. They allow the preparation of complex molecules with high stereoselectivity and good yields. Mechanistic and theoretical studies have been carried out on the transformation of 2-aminopyrimidines into imidazo[1,2-c]pyrimidines and guanidines, respectively, through ring closure and ring opening reactions, as well as the transamidation reactions through the ring closure and ring opening of guanidine derivatives, which constitute novel synthetic methods. Sepulveda Arques, Jose, Jose.Sepulveda@uv.es
La Vierge sans âge. Mythes et rites, images et parentés
2011
This article studies the status of images concerning the most important parental configuration of the Christian horizon: the relationship between the Virgin and her Son. The iconographic tradition, especially Byzantine, illustrated the different facets of this relationship, including those generated by the belief in the virgin birth and the Trinity. It also helped to stabilize the myths of the gospels (canonical and apocryphal) which promoted it. Strictly mixed with the liturgical word and popular rituals, the images help to understand better the symbolic work that underlies reversed filiation (visible for example in the Dormitio virginis). The sacred marriage is depicted in numerous images…
"Tutto quel che è, finisce". Guida a "L'Anello del Nibelungo" di Richard Wagner
2017
Il volume costituisce una guida completa e aggiornata al sistema drammaturgico-musicale wagneriano, alla sua ricchezza concettuale e ai presupposti estetici, filosofici e politici che ne furono alla base. È costituito da un’ampia introduzione dedicata alle suddette premesse (con numerose citazioni dagli scritti di Wagner), seguita da un ‘racconto’ dettagliato delle vicende – innanzi tutto "musicali" – dei quattro drammi, in altrettanti capitoli. La trattazione si avvale degli apporti ermeneutici più significativi, da quelli storici di Nietzsche, George Bernard Shaw, Thomas Mann, T. W. Adorno a quelli più recenti. Corredata degli esempi musicali relativi a tutti i Leitmotive e di tavole che …
All polarization-maintaining passively mode-locked fiber-ring ytterbium-doped laser; from net-normal to net-anomalous dispersion
2020
We investigated the behavior of a fiber-ring polarization-maintaining passively modelocked ytterbium-doped laser in a broad range of dispersion values; i.e., from highly net-normal to net-anomalous, with a special emphasis near the zero of chromatic dispersion. Different lengths of an ad hoc polarization-maintaining photonic crystal fiber were used as intracavity dispersion compensator to shift the operation of this laser from net-normal to the net-anomalous regime. The laser generated the shortest light pulses around the zero of dispersion: 6 ps / 7ps for −0.023 ps2 / 0.045 ps2 ; in both cases, pulses were not transform-limited, being theoretically possible an out-of-cavity recompression d…
The dual and the double of a Hopf algebroid are Hopf algebroids
2017
Let $H$ be a $\times$-bialgebra in the sense of Takeuchi. We show that if $H$ is $\times$-Hopf, and if $H$ fulfills the finiteness condition necessary to define its skew dual $H^\vee$, then the coopposite of the latter is $\times$-Hopf as well. If in addition the coopposite $\times$-bialgebra of $H$ is $\times$-Hopf, then the coopposite of the Drinfeld double of $H$ is $\times$-Hopf, as is the Drinfeld double itself, under an additional finiteness condition.
The 30 Year Search for the Compact Object in SN 1987A
2018
Despite more than 30 years of searches, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy ($0.1\times 10^{-26}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) at 213 GHz, 1 Lsun ($6\times 10^{-29}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) in optical if our line-of-sight is free of ejecta dust, and $10^{36}$ erg s$^{-1}$ ($2\times 10^{-30}$ erg s$^{-1}$ cm$^{-2}$ Hz$^{-1}$) in 2-10 keV X-rays. Our X-ray limits are an order of magnitude less constraining than previous limits because we use a…
Patterns of Puffing Activity in the Polytene Chromosomes of Drosophila Subobscura
1982
The puffs and Balbiani rings are the visible expression of sites of genetic activity (Beerman, 1952). Since Beermann’s original hypothesis, puffing patterns for several species of Diptera have been described. Thus for the genus Drosophila, Ashburner (1967, 1969a and 1969b) has reported the puffing pattern of Drosophila melanogaster and Drosophila simulans, Beredens (1965) of Drosophila hydei, and Moriwaki and Ito (1969) of Drosophila ananassae. In a previous paper Frutos and Latorre (1981) have determined puffing patterns of the J and U chromosomes of Drosophila subobscura. This species shows a rich chromosomal polymorphism and the puffing pattern of several chromosomal rearrangements of th…