Remarks on Higgs Inflation

We discuss models where the Higgs boson of the electroweak standard model plays the role of the inflaton. We focus on the question of the violation of perturbative unitarity due to the coupling of the Higgs boson either to the Ricci scalar or to the Einstein tensor and discuss the background dependence of the unitarity bounds. Our conclusion is that the simplest model which restricts itself to the standard model Higgs boson without introducing further degrees of freedom has a serious problem. However, in the asymptotically safe gravity scenario, the Higgs boson of the standard model could be the inflaton and no physics beyond the standard model is required to explain both inflation and the spontaneous breaking of the electroweak symmetry of the standard model.Comment: 9 pages. Version 2: Final Phys. Lett. B version, includes further discussion of singlet scala

Theory for the density of interacting quasi-localised modes in amorphous solids

Quasi-localised modes appear in the vibrational spectrum of amorphous solids at low-frequency. Though never formalised, these modes are believed to have a close relationship with other important local excitations, including shear transformations and two-level systems. We provide a theory for their frequency density, $D_{L}(\omega)\sim\omega^{\alpha}$, that establishes this link for systems at zero temperature under quasi-static loading. It predicts two regimes depending on the density of shear transformations $P(x)\sim x^{\theta}$ (with $x$ the additional stress needed to trigger a shear transformation). If $\theta>1/4$, $\alpha=4$ and a finite fraction of quasi-localised modes form shear transformations, whose amplitudes vanish at low frequencies. If $\theta<1/4$, $\alpha=3+ 4 \theta$ and all quasi-localised modes form shear transformations with a finite amplitude at vanishing frequencies. We confirm our predictions numerically

Unitarizing Higgs Inflation

We consider a simple extension of the Standard Model Higgs inflation with one new real scalar field which preserves unitarity up to the Planck scale. The new scalar field (called sigma) completes in the ultraviolet the theory of Higgs inflation by linearizing the Higgs kinetic term in the Einstein frame, just as the non-linear sigma model is unitarized into its linear version. The unitarity cutoff of the effective theory, obtained by integrating out the sigma field, varies with the background value of the Higgs field. In our setup, both the Higgs field and the sigma field participate in the inflationary dynamics, following the flat direction of the potential. We obtain the same slow-roll parameters and spectral index as in the original Higgs inflation but we find that the Hubble rate during inflation depends not only on the Higgs self-coupling, but also on the unknown couplings of the sigma field.Comment: 16 page

Organotypic brain slices: a model to study the neurovascular unit micro-environment in epilepsies.

BACKGROUND: It is now recognized that the neuro-vascular unit (NVU) plays a key role in several neurological diseases including epilepsy, stroke, Alzheimer\u27s disease, multiple sclerosis and the development of gliomas. Most of these disorders are associated with NVU dysfunction, due to overexpression of inflammatory factors such as vascular endothelial growth factor (VEGF). Various in vitro models have been developed previously to study the micro-environment of the blood-brain barrier (BBB). However none of these in vitro models contained a complete complement of NVU cells, nor maintained their interactions, thus minimizing the influence of the surrounding tissue on the BBB development and function. The organotypic hippocampal culture (OHC) is an integrative in vitro model that allows repeated manipulations over time to further understand the development of cell circuits or the mechanisms of brain diseases. METHODS/DESIGN: OHCs were cultured from hippocampi of 6-7 day-old Sprague Dawley rats. After 2 weeks in culture, seizures were induced by application of kainate or bicuculline into culture medium. The regulation of BBB integrity under physiological and pathological conditions was evaluated by immunostaining of the main tight junction (TJ) proteins and of the basal membrane of microvessels. To mimic or prevent BBB disassembly, we used diverse pro- or anti-angiogenic treatments. DISCUSSION: This study demonstrates that NVU regulation can be investigated using OHCs. We observed in this model system an increase in vascularization and a down-regulation of TJ proteins, similar to the vascular changes described in a chronic focus of epileptic patients, and in rodent models of epilepsy or inflammation. We observed that Zonula occludens-1 (ZO-1) protein disappeared after seizures associated with neuronal damage. In these conditions, the angiopoeitin-1 system was down-regulated, and the application of r-angiopoeitin-1 allowed TJ re-assembly. This article demonstrates that organotypic culture is a useful model to decipher the links between epileptic activity and vascular damage, and also to investigate NVU regulation in diverse neurological disorders

Determination of urban volatile organic compound emission ratios and comparison with an emissions database

During the NEAQS-ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from New York City and Boston. The emission ratios of VOCs relative to CO and acetylene were calculated using a method in which the ratio of a VOC with acetylene is plotted versus the photochemical age. The intercept at the photochemical age of zero gives the emission ratio. The so determined emission ratios were compared to other measurement sets, including data from the same location in 2002, canister samples collected inside New York City and Boston, aircraft measurements from Los Angeles in 2002, and the average urban composition of 39 U.S. cities. All the measurements generally agree within a factor of two. The measured emission ratios also agree for most compounds within a factor of two with vehicle exhaust data indicating that a major source of VOCs in urban areas is automobiles. A comparison with an anthropogenic emission database shows less agreement. Especially large discrepancies were found for the C2-C4 alkanes and most oxygenated species. As an example, the database overestimated toluene by almost a factor of three, which caused an air quality forecast model (WRF-CHEM) using this database to overpredict the toluene mixing ratio by a factor of 2.5 as well. On the other hand, the overall reactivity of the measured species and the reactivity of the same compounds in the emission database were found to agree within 30%. Copyright 2007 by the American Geophysical Union

Crisis pandémica: fenomenologia husserliana y el llamado a la responsabilidad

Este trabajo intenta iluminar desde un punto de vista fenomenológico las crisis ecológicas que han afectado a nuestro planeta y al mundo circundante de la vida en el siglo veintiuno, y en particular, la devastadora pandemia global que se desató el año 2020. Primero abordo ciertos aspectos histórico-críticos que preceden a la pandemia del 2020, y que se relacionan a la visión mecanicista moderna en las ciencias y la cultura. Luego, situada en la actitud natural, parto de esta ecocrisis actual como un “hilo conductor” para la interrogación retrospectiva que conduce a las raíces experienciales de todo sentido y validez objetiva, asumiendo la perspectiva de la primera persona y contratastándola con aspectos de una nueva y unificada visión sistémica de la vida. A continuación, destacando la paradoja del sujeto-en-el-mundo y el sujeto-para-el-mundo, examino la estructura del mundo de la vida como un camino o vía hacia el campo de la experiencia trascendental—aquel de la correlación entre la vida humana (encarnada, intersubjetiva e histórico-temoral) y el mundo, es decir, la estructura noético-noemática, con el objeto de mostrar cómo no es reductible a una auto-afección pasiva, sino que es la fuente originaria de una virtud espiritual y capacidad transformativa: la de la responsabilidad

Sound-propagation gap in fluid mixtures

We discuss the behavior of the extended sound modes of a dense binary hard-sphere mixture. In a dense simple hard-sphere fluid the Enskog theory predicts a gap in the sound propagation at large wave vectors. In a binary mixture the gap is only present for low concentrations of one of the two species. At intermediate concentrations sound modes are always propagating. This behavior is not affected by the mass difference of the two species, but it only depends on the packing fractions. The gap is absent when the packing fractions are comparable and the mixture structurally resembles a metallic glass.Comment: Published; withdrawn since ordering in archive gives misleading impression of new publicatio

El movimiento neocardenista: su perspectiva a corto plazo

El movimiento neo-cardenista ha vivido distintas etapas, en las que asume naturalezas diversas. Nace como un movimiento de cuadros y como una de las corrientes que confluyen y, con cierta regularidad, dirimen posiciones en el interior del partido oficial. Se convierte en movimiento de grupos y partidos de izquierda cuando se le expulsa de este partido. Se erige, a partir del 6 de julio de 1988, en movimiento político sui generis, pues propicia una movilización amplia. Después de dos años de jomada electoral, para mayo de 1990, el movimiento neocardenista se convierte en partido político: Partido de la Revolución Democrática

Musculoskeletal Applications of Elastography: a Pictorial Essay of Our Initial Experience

Elastography is an ultrasound-based newer imaging technique that is currently being used for the evaluation of breast lesions and hepatic pathology. It is also being evaluated for characterizing lesions of the prostate, thyroid, cervix and lymph nodes. We have applied real-time sonoelastography to a variety of musculoskeletal pathologies and here we report the findings of elastography for the evaluation of various musculoskeletal pathologies. Elastography of musculoskeletal lesions is not yet being routinely used in clinical practice, but it is being extensively researched