Search results for "Cone"
showing 10 items of 772 documents
Can we understand an auxetic pion-photon transition form factor within QCD?
2013
A state-of-the-art analysis of the pion-photon transition form factor is presented based on an improved theoretical calculation that includes the effect of a finite virtuality of the quasireal photon in the method of light-cone sum rules. We carry out a detailed statistical analysis of the existing experimental data using this method and by employing pion distribution amplitudes with up to three Gegenbauer coefficients a(2), a(4), a(6). Allowing for an error range in the coefficient a(6) approximate to 0, the theoretical predictions for gamma*gamma -> pi(0) obtained with nonlocal QCD sum rules are found to be in good agreement with all data that support a scaling behavior of the transition …
Light-cone quark model with spin force for the nucleon and Δ (1232)
1992
Abstract Electromagnetic structure functions for the nucleon, static observables for the nucleon and N → Δ (1232) transition form factors are calculated in a relativistic constituent quark model on the light cone. The model simulates the main effect of the spin force between quarks in terms of smaller (and lighter) scalar ud diquarks in the nucleon. The polarized proton structure function is found to agree with the EMC data.
On the regularity of critical and minimal sets of a free interface problem
2015
We study a free interface problem of finding the optimal energy configuration for mixtures of two conducting materials with an additional perimeter penalization of the interface. We employ the regularity theory of linear elliptic equations to study the possible opening angles of Taylor cones and to give a different proof of a partial regularity result by Fan Hua Lin [Calc Var. Partial Differential Equations, 1993].
B→ρsemileptonic decays and|Vub|
2014
We reevaluate the $B\to\rho\,l^+\nu_l$ decay width as a full $B\to\pi\pi\,l^+\nu_l$ four-particle decay, in which the two final pions are produced via an intermediate $\rho$ meson. The decay width can be written as a convolution of the $B\to\rho\,l^+\nu_l$ decay width, for an off-shell $\rho$, with the $\rho\to\pi\pi$ line shape. This allows to fully incorporate the effects of the finite $\rho$ meson width. As shown, consideration of the $\rho$ meson width effects increase the $|V_{ub}|$ value by some 8%, rendering it in better agreement with the determination based in the $B\to\pi$ decay. We take the $q^2$ dependence of the $B\to \rho$ semileptonic form factors from a dispersive Omn\`es re…
Estudi exploratori comparatiu del coneixement didàctic del contingut sobre piles galvàniques de professors de secundària en exercici i en formació
2021
En este estudio exploratorio se evalúa el conocimiento didáctico del contenido (CDC) sobre pilas galvánicas de profesores de secundaria en formación y en ejercicio. Además, este conocimiento se ha relacionado con los enfoques de enseñanza que prefieren. Para este propósito, se ha adaptado el instrumento CoRe de Loughran, Mulhall y Berry (2004) considerando dos situaciones: pila Daniell y pila voltaica simple. La muestra se compuso de 25 profesores en formación y de 15 profesores en ejercicio. El análisis de los resultados obtenidos hasta ahora sugiere que, en primer lugar, el CDC de los profesores de secundaria sobre pilas galvánicas no es el deseable; en segundo lugar, el CDC de los profes…
Flowers, Water accumulation and Corporate Social Responsibility: Certification of the Production of Roses and Claims for Environmental Justice in Ecu…
2018
La producción comercial de flores, el acaparamiento del agua y las luchas sociales por un reparto equitativo y un ambiente sano tienen una estrecha relación. Ecuador es el tercer exportador mundial de rosas. Cayambe-Tabacundo es la principal zona de producción y presenta una fuerte presión sobre los recursos hídricos. El agua es acaparada por las grandes empresas florícolas, quedando el resto para agricultura/ganadería de subsistencia en comunidades indígenas. Las florícolas utilizan las certificaciones ambientales y de comercio justo privadas, pero los estándares son permisivos. Este artículo analiza las relaciones de poder detrás de las prácticas de certificación de flores. Concluye que s…
Technophysis. Le tecniche della natura
2022
Una ricostruzione dei modelli che strutturano il rapporto tra tecnica e natura dall’epi- ca omerica alle teorie evoluzionistiche passando per classici della filosofia come Platone, Aristotele e Bacone. Una parabola storico-critica guidata da un’idea di technophysis in cui ripensare le opposizioni tradizionali alla luce di nuovi equilibri. Queste le coordinate di un percorso che non rinuncia all’antico per costruire una didattica sensibile alle sfide del contemporaneo.
Sulfur’s role in the flame retardancy of thio-ether–linked hyperbranched polyphosphoesters in epoxy resins
2020
Abstract Hyperbranched polyphosphoesters are promising multifunctional flame retardants for epoxy resins. These polymers were prepared via thiol-ene polyaddition reactions. While key chemical transformations and modes of actions were elucidated, the role of sulfur in the chemical composition remains an open question. In this study, the FR-performance of a series of phosphorus-based flame retardant additives with and without sulfur (thio-ethers or sulfones) in their structure are compared. The successful synthesis of thio-ether or sulfone-containing variants is described and verified by 1H and 31P NMR, also FTIR and MALDI-TOF. A decomposition process is proposed from pyrolytic evolved gas an…
Rascló, Polluela pintoja (VER0000095)
1946
Altres noms vulgars: Spotted crake (Anglès), Marouette ponctuée (Francès), Tüpfelsumpfhuhn (Alemany) Gabinet de Vertebrats (Departament de Zoologia), Facultat de Ciències Biològiques (Campus de Burjassot), C/ Doctor Moliner, s/n, Bloque B. 5é plant, Burjassot (Valencia). Armari: 10-1 Canet de Berenguer 25/4/1946
Regularization of perturbed state-dependent sweeping processes with nonregular sets
2018
International audience; In this paper, we prove the convergence strongly pointwisely (up to a subsequence) of Moreau-Yosida regularization of perturbed state-dependent sweeping process with nonregular (subsmooth and positively alpha-far) sets in separable Hilbert spaces. Some relevant consequences are indicated.