2,266 research outputs found
The quantum integrable system
The quantum integrable system is a 3D system with rational potential
related to the non-crystallographic root system . It is shown that the
gauge-rotated Hamiltonian as well as one of the integrals, when written
in terms of the invariants of the Coxeter group , is in algebraic form: it
has polynomial coefficients in front of derivatives. The Hamiltonian has
infinitely-many finite-dimensional invariant subspaces in polynomials, they
form the infinite flag with the characteristic vector \vec \al\ =\ (1,2,3).
One among possible integrals is found (of the second order) as well as its
algebraic form. A hidden algebra of the Hamiltonian is determined. It is
an infinite-dimensional, finitely-generated algebra of differential operators
possessing finite-dimensional representations characterized by a generalized
Gauss decomposition property. A quasi-exactly-solvable integrable
generalization of the model is obtained. A discrete integrable model on the
uniform lattice in a space of -invariants "polynomially"-isospectral to
the quantum model is defined.Comment: 32 pages, 3 figure
Primordial black holes and gravitational waves from dissipation during inflation
We study the generation of a localized peak in the primordial spectrum of
curvature perturbations from a transient dissipative phase during inflation,
leading to a large population of primordial black holes. The enhancement of the
power spectrum occurs due to stochastic thermal noise sourcing curvature
fluctuations. We solve the stochastic system of Einstein equations for many
realizations of the noise and obtain the distribution for the curvature power
spectrum. We then propose a method to find its expectation value using a
deterministic system of differential equations. In addition, we find a single
stochastic equation whose analytic solution helps to understand the main
features of the spectrum. Finally, we derive a complete expression and a
numerical estimate for the energy density of the stochastic background of
gravitational waves induced at second order in perturbation theory. This
includes the gravitational waves induced during inflation, during the
subsequent radiation epoch and their mixing. Our scenario provides a novel way
of generating primordial black hole dark matter with a peaked mass distribution
and a detectable stochastic background of gravitational waves from inflation.Comment: 48 pages, 11 figures; matches published version in JCAP; typo
corrected, the rest of the paper is unchange
Phase space contraction and quantum operations
We give a criterion to differentiate between dissipative and diffusive
quantum operations. It is based on the classical idea that dissipative
processes contract volumes in phase space. We define a quantity that can be
regarded as ``quantum phase space contraction rate'' and which is related to a
fundamental property of quantum channels: non-unitality. We relate it to other
properties of the channel and also show a simple example of dissipative noise
composed with a chaotic map. The emergence of attaractor-like structures is
displayed.Comment: 8 pages, 6 figures. Changes added according to refferee sugestions.
(To appear in PRA
Noise models for superoperators in the chord representation
We study many-qubit generalizations of quantum noise channels that can be
written as an incoherent sum of translations in phase space. Physical
description in terms of the spectral properties of the superoperator and the
action in phase space are provided. A very natural description of decoherence
leading to a preferred basis is achieved with diffusion along a phase space
line. The numerical advantages of using the chord representation are
illustrated in the case of coarse-graining noise.Comment: 8 pages, 5 .ps figures (RevTeX4). Submitted to Phys. Rev. A. minor
changes made, according to referee suggestion
SWOT Analysis Applied to Wheat Straw Utilization as a Biofuel in Mexico
Wheat is one of the main crops worldwide with a production of 733 million of tons by 2015. By 2013, the wheat grain production in Mexico was 3,357,307 t. Wheat straw is generated as a biomass waste once the wheat is harvested. However, the agricultural biomass waste has acquired international relevance as a source of bioenergy. The utilization of bioenergy has significant environmental benefits, and also economic benefits because the biomass waste is valorized as biofuel. The use of wheat straw as raw material for any productive process presents diverse factors that must be considered. Among those factors are the low density of biomass, handling and high transportation cost, an attractive heating value, and the physicochemical characterization. Therefore, the aim of this work was to apply the SWOT analysis to wheat straw utilization as a biofuel in Mexico. The main findings highlighted an estimation of 4,612,950.23 t of wheat straw generated. The experimental results of proximate analysis were 64.42% volatile matter, 19.49% fixed carbon and 16.09% ash. The higher heating was 14.86 MJ/kg. An energy potential of 69 PJ per agricultural cycle was calculated, equivalent to 19% of the biomass energy share reported in Mexico’s National Energy Balance, by 2014
Interaction of 8 He with 208Pb at near-barrier energies: 4 He and 6 He production
Spanish Ministry of Economy and Competitiveness-FPA-2010-22131-CO2-01 (FINURA) y FPA2013-47327-C2-1-RMinistry of Science and Higher Education of Poland-N202 033637National Science Centre of Poland-2013/08/M/ST2/00257 (LEA-COPIGAL) y 2014/14/M/ST2/00738 (COPIN-INFN Collaboration)European Science Foundation-EUI2009-04163432 (EUROGENESIS
Retinoic Acid Modulates PTGDR Promoter Activity
[EN] Background and objective: Vitamin A has been linked to the development of allergic diseases although its role is not fully understood, Retinoic acid (RA), a metabolite of Vitamin A, has been previously associated with the prostaglandin pathway, and PTGDR, a receptor of PGD2, has been proposed as a candidate gene in allergy and asthma. Considering the role of PTGDR in allergy, the goal of this study was to analyze the effect of RA on the activation of the promoter region of the PTGDR gene.
Methods: A549 lung epithelial cells were transfected with 4 combinations of genetic variants of the PTGDR promoter and stimulated with all-trans RA (ATRA); luciferase assays were performed using the Dual Luciferase Reporter System, and real-time quantitative polymerase chain reaction was used to measure the expression of PTGDR, CYP26A1, RARA, RARB, RARG, and RXRA in basal A549 cell cultures and after ATRA treatment. We also performed an in silico analysis.
Results: After ATRA treatment increased expression of CYP26A1 (12-fold) and RARB (4-fold) was detected. ATRA activated PTGDR promoter activity in transfected cells (P<.001) and RA response element sequences were identified in silico in this promoter region.
Conclusions: RA modulated PTGDR promoter activity. Differential response to RA and to new treatments based on PTGDR modulation could depend on genetic background in allergic asthmatic patients.Instituto de Salud Carlos III; European Regional Development Fund (ERDF); Junta de Castilla y León; Fundación Botín-Universidad de Salamanca; Sociedad Española de Alergología e
Inmunología Clínica; Fundación Salud 200
Triplet formation inhibits amplified spontaneous emission in perylene-based polycyclic aromatic hydrocarbons
Polycyclic Aromatic Hydrocarbons (PAHs) have demonstrated potential as active laser materials, showing good Amplified Stimulated Emission (ASE) properties. However, the molecular origin of their ASE properties is still unclear and depends on the particular compound. In this work we study the ASE properties of polystyrene films hosting three different perylene-based PAHs YZ-1, YZ-2 and YZ-3, where only YZ-3 has displayed ASE. Their molecular structure has been systematically changed to establish the connection between their molecular structure and their ASE properties. A complete spectroscopic study, with ground state and time-resolved techniques, show that, even at low yields, triplets play a critical role as a major loss mechanism. Their slow relaxation to ground state completely hinders the required unbalance of the S1 and S0 states for succesful ASE. Quantum chemical calculations suggest that a lower triplet density of states for YZ-3 is responsible for the blockage in triplet formation and, therefore, does not restrict ASE. This work not only presents a new PAH showing ASE, but also unequivocable proves the massive importance of triplet states in the development of organic lasers.JW acknowledges financial support from A*STAR AME grant (A20E5c0089). The group at the University of Alicante thanks financial support from the “Ministerio de Ciencia e Innovación” (MCIN) of Spain and the European Regional Development Fund (grant No. PID2020-119124RB-I00) and from the Generalitat Valenciana though grant No. AICO/2021/093. Besides, this study is part of the Advanced Materials program supported by the Spanish MCIN with funding from European Union Next Generation EU and by Generalitat Valenciana (grant no. MFA/2022/045). The group at the UA thanks Dr. J.M Villalvilla and Dr. J.A. Quintana for useful discussions. We also thank the Research Central Services (SCAI) of the University of Málaga for the access to the EVI, EEL and MENL to perform ground state and transient spectroscopic characterisation. JC thanks funding provided by MINECO/FEDER (PID2021-127127NB-I00, PID2019-110305GB-I00) and Junta de Andalucía (PROYEXCEL-0328)
Wheat Straw Open Burning: Emissions and Impact on Climate Change
The state of Baja California, Mexico, is the second national wheat producer. Mexicali, the capital of Baja California, is the primary wheat producer, and it represents the most significant crop in the valley, with 90,609 ha of a cultivated surface by 2015; it leads to a wheat production of 585,334 t and a generation of 661,446 t of wheat straw as agricultural residue. The 15% of this waste has various uses. The 85% of wheat straw is open burnt in situ to prepare the farmland for the next agricultural cycle. Through the development of an emissions and energy model on iThink®, the emissions of 6,185 t of PM, 35,983 t of CO, and 1,125 t of CH4 considering a headfire burning or 3,373 t of PM, 30,360 t of CO, and 731 t of CH4 by backfire burning were estimated. Also, the wheat straw wasted energy was estimated at 8.15 PJ by 2015, with a lower heating value of 14.50 MJ/kg determined experimentally. The results highlight that for each hectare of harvested wheat, 6.205 t of wheat straw are generated and burnt. It represents the emission of pollutants and 89,972.50 MJ of wasted energy
Clinically significant anxiety as a risk factor for dementia in the elderly community
Objective: To evaluate whether clinically significant anxiety is an independent risk factor for dementia, taking into account both depression among potentially confounding factors and the competing risk of death.
Method: During the Zaragoza Dementia and Depression (ZARADEMP) study, a random sample of community dwellers aged 55 years or older was assessed (n = 4803), and a two-wave, 4.5-year follow-up was completed. Geriatric Mental State (GMS)-AGECAT criteria were used to diagnose anxiety and DSM-IV criteria were applied to diagnose incident dementia. The multivariate Fine and Gray regression model was implemented to calculate dementia risk.
Results: Compared with non-cases (GMS-AGECAT criteria), the incidence rate of dementia was significantly higher in subcases of anxiety, and particularly significant in the cases of anxiety (incidence rate ratio (IRR): 2.77; P = 0.010). Cases of anxiety, but not subcases, at baseline were significantly associated with dementia risk (adjusted subdistribution hazard ratio (SHR): 2.7; P = 0.019).
Conclusion: Clinically significant anxiety is associated with an almost threefold increase in the risk of dementia in the population, even when controlling for depression and considering mortality in the competing risks model
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