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.

Observation of Gravitational Waves from Two Neutron Star–Black Hole Coalescences

Abstract: We report the observation of gravitational waves from two compact binary coalescences in LIGO’s and Virgo’s third observing run with properties consistent with neutron star–black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo and the second by all three LIGO–Virgo detectors. The source of GW200105 has component masses 8.9−1.5+1.2 and 1.9−0.2+0.3M⊙ , whereas the source of GW200115 has component masses 5.7−2.1+1.8 and 1.5−0.3+0.7M⊙ (all measurements quoted at the 90% credible level). The probability that the secondary’s mass is below the maximal mass of a neutron star is 89%–96% and 87%–98%, respectively, for GW200105 and GW200115, with the ranges arising from different astrophysical assumptions. The source luminosity distances are 280−110+110 and 300−100+150Mpc , respectively. The magnitude of the primary spin of GW200105 is less than 0.23 at the 90% credible level, and its orientation is unconstrained. For GW200115, the primary spin has a negative spin projection onto the orbital angular momentum at 88% probability. We are unable to constrain the spin or tidal deformation of the secondary component for either event. We infer an NSBH merger rate density of 45−33+75Gpc−3yr−1 when assuming that GW200105 and GW200115 are representative of the NSBH population or 130−69+112Gpc−3yr−1 under the assumption of a broader distribution of component masses.

Nonlocal Diffusion Problems

Abstract: Nonlocal diffusion problems arise in a wide variety of applications, including biology, image processing, particle systems, coagulation models, and mathematical finance. These types of problems are also of great interest for their purely mathematical content. This book presents recent results on nonlocal evolution equations with different boundary conditions, starting with the linear theory and moving to nonlinear cases, including two nonlocal models for the evolution of sandpiles. Both existence and uniqueness of solutions are considered, as well as their asymptotic behaviour. Moreover, the authors present results concerning limits of solutions of the nonlocal equations as a rescaling parameter tends to zero. With these limit procedures the most frequently used diffusion models are recovered: the heat equation, the $p$-Laplacian evolution equation, the porous media equation, the total variation flow, a convection-diffusion equation and the local models for the evolution of sandpiles due to Aronsson-Evans-Wu and Prigozhin. Readers are assumed to be familiar with the basic concepts and techniques of functional analysis and partial differential equations. The text is otherwise self-contained, with the exposition emphasizing an intuitive understanding and results given with full proofs. It is suitable for graduate students or researchers. The authors cover a subject that has received a great deal of attention in recent years. The book is intended as a reference tool for a general audience in analysis and PDEs, including mathematicians, engineers, physicists, biologists, and others interested in nonlocal diffusion problems.

Prevalence of corneal astigmatism before cataract surgery.

Abstract: Purpose To analyze the prevalence and presentation patterns of corneal astigmatism in cataract surgery candidates. Setting University of Valencia, Valencia, Spain. Methods Refractive and keratometric values were measured before surgery in patients having cataract extraction. Descriptive statistics of refractive and keratometric cylinder data were analyzed and correlated by age ranges. Results Refractive and keratometric data from 4540 eyes of 2415 patients (mean age 60.59 years ± 9.87 [SD]; range 32 to 87 years) differed significantly when the patients were divided into 10-year subsets. There was a trend toward less negative corneal astigmatism values, except the steepest corneal radius and the J 45 vector component, in older groups (Kruskal-Wallis, P Conclusions Corneal astigmatism less than 1.25 D was present in most cataract surgery candidates; it was higher in about 22%, with slight differences between the various age ranges. This information is useful for intraocular lens (IOL) manufacturers to evaluate which age ranges concentrate the parameters most frequently needed in sphere and cylinder powers and for surgeons to evaluate which IOLs provide the most effective power range.

Mitochondrial oxidative stress plays a key role in aging and apoptosis.

Abstract: Harman first suggested in 1972 that mitochondria might be the biological clock in aging, noting that the rate of oxygen consumption should determine the rate of accumulation of mitochondrial damage produced by free radical reactions. Later in 1980 Miquel and coworkers proposed the mitochondrial theory of cell aging. Mitochondria from postmitotic cells use O2 at a high rate, hence releasing oxygen radicals that exceed the cellular antioxidant defences. The key role of mitochondria in cell aging has been outlined by the degeneration induced in cells microinjected with mitochondria isolated from fibroblasts of old rats, especially by the inverse relationship reported between the rate of mitochondrial production of hydroperoxide and the maximum life span of species. An important change in mitochondrial lipid composition is the age-related decrease found in cardiolipin content. The concurrent enhancement of lipid peroxidation and oxidative modification of proteins in mitochondria further increases mutations and oxidative damage to mitochondrial DNA (mtDNA) in the aging process. The respiratory enzymes containing the defective mtDNA-encoded protein subunits may increase the production of reactive oxygen species, which in turn would aggravate the oxidative damage to mitochondria. Moreover, superoxide radicals produced during mitochondrial respiration react with nitric oxide inside mitochondria to yield damaging peroxynitrite. Treatment with certain antioxidants, such as sulphur-containing antioxidants, vitamins C and E, or the Ginkgo biloba extract EGb 761, protects against the age-associated oxidative damage to mtDNA and the oxidation of mitochondrial glutathione. Moreover, the EGb 761 extract also prevents changes in mitochondrial morphology and function associated with aging of the brain and liver.