Invariance Violation Extends the Cosmic Ray Horizon ?

We postulate in the present paper that the energy-momentum relation is modified for very high energy particles to violate Lorentz invariance and the speed of photon is changed from the light velocity c. The violation effect is amplified, in a sensitive way to detection, through the modified kinematical constraints on the conservation of energy and momentum, in the absorption process of gamma-rays colliding against photons of longer wavelengths and converting into an electron-positron pair. For gamma-rays of energies higher than 10 TeV, the minimum energy of the soft photons for the reaction and then the absorption mean free path of gamma-rays are altered by orders of magnitude from the ones conventionally estimated. Consideration is similarly applied to high energy cosmic ray protons. The consequences may require the standard assumptions on the maximum distance that very high energy radiation can travel from to be revised.Comment: 14 pages, 1 figure, to be published in Ap J Letter

Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation

We examine what the absorbed spectra of extra-galactic TeV gamma-ray sources, such as blazars, would look like in the presence of Lorentz invariance violation (LIV). Pair-production with the extra-galactic background light modifies the observed spectra of such sources, and we show that a violation of Lorentz invariance would generically have a dramatic effect on this absorption feature. Inspecting this effect, an experimental task likely practical in the near future, can provide unique insight on the possibility of LIV.Comment: Published in Phys. Rev.

Functional neuroanatomy of contextual acquisition of concrete and abstract words

The meaning of a novel word can be acquired by extracting it from linguistic context. Here we simulated word learning of new words associated to concrete and abstract concepts in a variant of the human simulation paradigm that provided linguistic context information in order to characterize the brain systems involved. Native speakers of Spanish read pairs of sentences in order to derive the meaning of a new word that appeared in the terminal position of the sentences. fMRI revealed that learning the meaning associated to concrete and abstract new words was qualitatively different and recruited similar brain regions as the processing of real concrete and abstract words. In particular, learning of new concrete words selectively boosted the activation of the ventral anterior fusiform gyrus, a region driven by imageability, which has previously been implicated in the processing of concrete words

Nonequilibrium Luminescence At The E0+Δ0 Gap In Gaas With Si-δ Doping

We studied the light scattering spectra of three molecular beam epitaxy GaAs samples with Si-δ doping. A broad feature appears in these spectra which is similar to that attributed by other authors to resonant Raman scattering by electronic intersubband transitions. By studying the dependence of this emission on exciting laser photon energy we believe that this line is really produced by nonequilibrium luminescence at the E0+Δ 0 gap.71115619562

Determinació de radiocarboni d'origen antropogènic

Tots els materials, tant vivents corn inerts, poden contenir traces de radioactivitat natural a causa de l'existència de radionúclids presents a la terra des del moment de la seva formació (series de l'U-235, U-238, Th-232 i els radionúclids independents K-40, Sr-87 i Sm-187) o bé de la formació continua per interacció dels raigs còsmics amb els elements terrestres (H-3, Be-7, C-14). El radiocarboni es produeix segons la reacció nuclear següent: 14 7N+0 1n ---------- 14 6C+ 1 1H i ha mantingut constant la seva proporció en relació amb el carboni total al llarg del temps perquè s'ha establert un equilibri entre la seva formació i la seva desaparició. Darrerament l'home ha alterat aquest equilibri principalment a causa de l'ús de 1'energia nuclear per a diverses finalitats, i cal pensar que en el futur hi haurà un increment de l'ús d'aquest tipus d'energia. Els vegetals incorporen el radiocarboni atmosfèric a llurs teixits a través de la fotosíntesi, d'aquests passa als teixits animals i finalment s'incorpora a l'home, que clou la cadena tròfica. Un augment del contingut de radiocarboni en els dipòsits naturals produeix un increment del contingut de radiocarboni en cadascuna de les baules de la cadena tròfica, i finalment pot causar efectes cancerígens en l'home. Són necessaris, doncs, cada vegada més, el mesurament i el control dels nivells de concentració d'aquest radionúclid. En aquest treball presentem els materials que cal analitzar amb aquesta finalitat, i llur tractament per a l'obtenció de CO2 i posterior transformació d'aquest en benzè per a poder procedir a la determinació de 1'activitat per centelleig líquid. Tamb´r avaluem les condicions òptimes d'aquesta determinació tal corn són dutes a terme en el laboratori instal•lat al Departament de Química Anàlitica de la Universitat de Barcelona

Processing factors that affect the balance of alcohols and alkyl esters during ‘Arbequina’ olive oil production: Separation and clarification steps

The aim of this study was to assess how different conditions used on the centrifugation step during olive oil extraction affect its quality by considering the balance of fatty acid alkyl esters (FAAEs) and their precursor alcohols. All the experiments were carried out under real working conditions in a two-phase decanter followed by a vertical centrifuge (VC) and different water injection doses and paste injection rates were tested. The fruits used were from ‘Arbequina’ variety at two different maturity stages and the balances of alcohols and FAAEs were measured at the outlets of both, decanter and VC, with respect to the system inlet. Results show that the paste injection rate affects the content of alcohols and FAAEs in the final oil, which tend to increase when working closer to the maximum capacity of the decanter. Different behaviors have been detected when dealing with unripe or ripe fruits. Similarly, the water addition doses have different effects on the FAAEs and alcohols formation depending on the maturity status. Therefore, both the decanter and the step decanter to vertical centrifuge are key points that, when properly controlled, allow minimizing FAAEs formation, which is essential for obtaining quality oils.info:eu-repo/semantics/acceptedVersio

Effect of Hopper Loading on the Formation of Alkyl Alcohols in Olive Fruits and Its Relationship with Sensory Quality Losses of Virgin Olive Oil

The storage of olives in large hoppers is a widespread practice in oil mills, but these large volumes and their unloading can cause a physical deterioration of the olives that will affect the quality of the oil obtained. This research deals with the effect of hopper charge on the formation of alkyl alcohols in olive fruits and its relationship with the sensory quality losses of ‘Arbequina’ virgin olive oil. The contents of ethanol, methanol, and acetaldehyde were measured in olive samples loaded and stored for a short time in a large hopper and analyzed at three different hopper-discharging times, which are related to three different positions inside the hopper. The corresponding oil from each sampling was obtained by using ABENCOR and was evaluated by a trained tasting panel. Results showed that the ethanol content in olives increased during their storage in the hopper, while methanol and acetaldehyde contents did not show significant differences. Regarding their position in the hopper, fruits located at the bottom or on the lateral sides showed a greater deterioration. The sensory analyses showed an inverse relationship between the positive attributes of olive oils and their content of alcohols.The authors thank the International Olive Oil Council IOOC for the fellowship [T1/COI-DOCT 1/16] and the Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI) (project PID2019-104269RR-C33). The authors also thank the Cooperative La Granadella mill for allowing us to carry out the experiments in their facilities and the official olive oil tasting panel of Catalonia, as well. A.R. and J.-F.H. acknowledge the Generalitat of Catalonia for the financial support (CERCA Program). Finally, A. B also thank his founding by the “Ministerio de Universidades and European Union- NextGeneration” in the framework “Ayudas para la Recualificación del Sistema Universitario Español” in modality “MARGARITA SALAS” (2021URV-MS-30).info:eu-repo/semantics/publishedVersio

Functional neuroanatomy of meaning acquisition from context

An important issue in language learning is how new words are integrated in the brain representations that sustain language processing. To identify the brain regions involved in meaning acquisition and word learning, we conducted a functional magnetic resonance imaging study. Young participants were required to deduce the meaning of a novel word presented within increasingly constrained sentence contexts that were read silently during the scanning session. Inconsistent contexts were also presented in which no meaning could be assigned to the novel word. Participants showed meaning acquisition in the consistent but not in the inconsistent condition. A distributed brain network was identified comprising the left anterior inferior frontal gyrus (BA 45), the middle temporal gyrus (BA 21), the parahippocampal gyrus, and several subcortical structures (the thalamus and the striatum). Drawing on previous neuroimaging evidence, we tentatively identify the roles of these brain areas in the retrieval, selection, and encoding of the meaning

Self-consistency in Theories with a Minimal Length

The aim of this paper is to clarify the relation between three different approaches of theories with a minimal length scale: A modification of the Lorentz-group in the 'Deformed Special Relativity', theories with a 'Generalized Uncertainty Principle' and those with 'Modified Dispersion Relations'. It is shown that the first two are equivalent, how they can be translated into each other, and how the third can be obtained from them. An adequate theory with a minimal length scale requires all three features to be present.Comment: typos corrected, published with new title following referee's advic