University of Valencia

About: University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 27096 authors who have published 65669 publications receiving 1765689 citations. The organization is also known as: Universitat de València & UV.

HST/WFC3 Confirmation of the Inside-out Growth of Massive Galaxies at 0 < z < 2 and Identification of Their Star-forming Progenitors at z ~ 3

Abstract: We study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n $_c$ = 1.4 { imes} 10$^{-4}$ Mpc$^{-3}$ to z ~{} 3. Structural parameters were measured by fitting Sersic profiles to high-resolution CANDELS HST WFC3 J $_{125}$ and H $_{160}$ imaging in the UKIDSS-UDS at 1 {lt} z {lt} 3 and ACS I $_{814}$ imaging in COSMOS at 0.25 {lt} z {lt} 1. At a given redshift, we selected the HST band that most closely samples a common rest-frame wavelength so as to minimize systematics from color gradients in galaxies. At fixed n $_c$, galaxies grow in stellar mass by a factor of ~{}3 from z ~{} 3 to z ~{} 0. The size evolution is complex: galaxies appear roughly constant in size from z ~{} 3 to z ~{} 2 and then grow rapidly to lower redshifts. The evolution in the surface mass density profiles indicates that most of the mass at r {lt} 2 kpc was in place by z ~{} 2, and that most of the new mass growth occurred at larger radii. This inside-out mass growth is therefore responsible for the larger sizes and higher Sersic indices of the descendants toward low redshift. At z {lt} 2, the effective radius evolves with the stellar mass as r$_e$ vpropM $^{2.0}$, consistent with scenarios that find dissipationless minor mergers to be a key driver of size evolution. The progenitors at z ~{} 3 were likely star-forming disks with r$_e$ ~{} 2 kpc, based on their low Sersic index of n ~{} 1, low median axis ratio of b/a ~{} 0.52, and typical location in the star-forming region of the U - V versus V - J diagram. By z ~{} 1.5, many of these star-forming disks disappeared, giving rise to compact quiescent galaxies. Toward lower redshifts, these galaxies continued to assemble mass at larger radii and became the local ellipticals that dominate the high-mass end of the mass function at the present epoch. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Nonperturbative approach to effective chiral lagrangians and meson interactions

Abstract: We develop a coupled channel unitary approach describing the behavior at higher energies of systems whose low-energy dynamics is given by effective O(p^2) and O(p^4) chiral Lagrangians. Our free parameters are those of the O(p^4) Lagrangian. When applied to the meson-meson interaction, it yields a remarkable agreement with data up to √2≅1.2 GeV, dynamically generating the σ , f_0 α_0, ρ, and K* resonances. Further applications are also proposed.

Preterm birth, infant weight gain, and childhood asthma risk : A meta-analysis of 147,000 European children

Abstract: BACKGROUND: Preterm birth, low birth weight, and infant catch-up growth seem associated with an increased risk of respiratory diseases in later life, but individual studies showed conflicting results. OBJECTIVES: We performed an individual participant data meta-analysis for 147,252 children of 31 birth cohort studies to determine the associations of birth and infant growth characteristics with the risks of preschool wheezing (1-4 years) and school-age asthma (5-10 years). METHODS: First, we performed an adjusted 1-stage random-effect meta-analysis to assess the combined associations of gestational age, birth weight, and infant weight gain with childhood asthma. Second, we performed an adjusted 2-stage random-effect meta-analysis to assess the associations of preterm birth (gestational age <37 weeks) and low birth weight (<2500 g) with childhood asthma outcomes. RESULTS: Younger gestational age at birth and higher infant weight gain were independently associated with higher risks of preschool wheezing and school-age asthma (P < .05). The inverse associations of birth weight with childhood asthma were explained by gestational age at birth. Compared with term-born children with normal infant weight gain, we observed the highest risks of school-age asthma in children born preterm with high infant weight gain (odds ratio [OR], 4.47; 95% CI, 2.58-7.76). Preterm birth was positively associated with an increased risk of preschool wheezing (pooled odds ratio [pOR], 1.34; 95% CI, 1.25-1.43) and school-age asthma (pOR, 1.40; 95% CI, 1.18-1.67) independent of birth weight. Weaker effect estimates were observed for the associations of low birth weight adjusted for gestational age at birth with preschool wheezing (pOR, 1.10; 95% CI, 1.00-1.21) and school-age asthma (pOR, 1.13; 95% CI, 1.01-1.27). CONCLUSION: Younger gestational age at birth and higher infant weight gain were associated with childhood asthma outcomes. The associations of lower birth weight with childhood asthma were largely explained by gestational age at birth.

Health risks and potential remedies during prolonged lockdowns for coronavirus disease 2019 (COVID-19).

Abstract: As coronavirus disease 2019 (COVID-19) pandemic continues, an increasing number of countries and territories are adopting restrictive measures based on physical ("social") distancing, aimed at preventing human-to-human transmission and thereby limiting virus propagation. Nationwide lockdowns, encompassing mass quarantine under stay-at-home ordinances, have already been proven effective to contain the COVID-19 outbreak in some countries. Nevertheless, a prolonged homestay may also be associated with potential side effects, which may jeopardize people's health and thus must be recognized and mitigated in a way without violating local ordinances. Some of the most important undesirable consequences of prolonged homestay such as physical inactivity, weight gain, behavioral addiction disorders, insufficient sunlight exposure and social isolation will be critically addressed in this article, which also aims to provide some tentative recommendations for the alleviation of side effects.

Pinch Technique: Theory and Applications

Abstract: We review the theoretical foundations and most important physical applications of the Pinch Technique (PT). This method allows the construction of off-shell Green's functions in non-Abelian gauge theories that are independent of the gauge-fixing parameter and satisfy ghost-free Ward identities. We first present the diagrammatic formulation of the technique in QCD, deriving at one loop the gauge independent gluon self-energy, quark-gluon vertex, and three-gluon vertex, together with their Abelian Ward identities. The generalization to theories with spontaneous symmetry breaking is carried out in detail, and the connection with the optical theorem and the dispersion relations are explained within the electroweak sector of the Standard Model. The equivalence between the PT and the Feynman gauge of the Background Field Method (BFM) is elaborated, and the crucial differences between the two methods are critically scrutinized. The Batalin-Vilkovisky quantization method and the general formalism of algebraic renormalization are introduced, and the all-order generalization of the PT is thoroughly examined. The extension of the PT to the non-perturbative domain of the QCD Schwinger-Dyson equations is presented systematically, and the main advantages of the resulting self-consistent truncation scheme are discussed. A plethora of physical applications relying on the PT are reviewed, such as the definition of gauge-independent off-shell form-factors, the construction of non-Abelian effective charges, the gauge-invariant treatment of resonant transition amplitudes and unstable particles, and the dynamical generation of an effective gluon mass.