Factorizing the time evolution operator

There is a widespread belief in the quantum physical community, and in textbooks used to teach Quantum Mechanics, that it is a difficult task to apply the time evolution operator Exp{-itH/h} on an initial wave function. That is to say, because the hamiltonian operator generally is the sum of two operators, then it is a difficult task to apply the time evolution operator on an initial wave function f(x,0), for it implies to apply terms operators like (a+b)^n. A possible solution of this problem is to factorize the time evolution operator and then apply successively the individual exponential operator on the initial wave function. However, the exponential operator does not directly factorize, i. e. Exp{a+b} is not equal to Exp{a}Exp{b}. In this work we present a useful procedure for factorizing the time evolution operator when the argument of the exponential is a sum of two operators, which obey specific commutation relations. Then, we apply the exponential operator as an evolution operator for the case of elementary unidimensional potentials, like the particle subject to a constant force and the harmonic oscillator. Also, we argue about an apparent paradox concerning the time evolution operator and non-spreading wave packets addressed previously in the literature.Comment: 24 pages; added references; one figure change

Obtención de un polímero de tipo Elastina modificado con secuencias Bioactivas y Biodegradables, para su aplicación en ingeniería

La matriz extracelular es uno de los principales elementos reguladores de la actividad celular. Los diferentes módulos de las macromoléculas que la componen son capaces de desencadenar señales que activan diferentes rutas intracelulares que organizan las funciones vitales de las células. La ingeniería de tejidos se dedica a desarrollar sistemas capaces de imitar, temporalmente, el comportamiento de la matriz extracelular con objeto de promover la regeneración o el reemplazo de tejidos y órganos dañados, actuando como un soporte atractivo para las células que deben adherirse y crecer sobre ella, hasta reemplazarla por tejido sano. En este trabajo se describe el proceso de diseño y producción de un polímero de tipo elastina que se ha funcionalizado con secuencias bioactivas que añaden actividades específicas al andamio o soporte celular que constituye la elastina. Así,algunos dominios elastoméricos se modificaron con el aminoácido lisina para poder entrecruzar las moléculas de polímero y conseguir matrices. También se incluyó la secuencia REDV, presente el dominio CS5 de la fibronectina humana, como motivo de adhesión celular. Por último, el polímero se funcionalizó con secuencias diana de enzimas proteolíticas para mejorar su bioprocesabilidad.Extracellular matrix (ECM) is a major component for the regulation of cell activity. The different modules of the proteins which constitute the extracellular matrix macromolecules represent for the cells which enter in contact with them, new signals capable of activating several intracellular signaling pathways, resulting in the modulation of numerous cell functions. Tissue engineering tries to develop new materials based on these components as scaffolds for cells to promote their adhesion and growth. In this work, genetic engineering techniques were used to design and biosynthesize an extracellular matrix analogue based in the elastin component. The structural base of our scaffold is an elastin –derived sequence which confers an adequate mechanical behavior. In addition, several domains were included, for adding new bioactivities to this elastin-like polymer (ELP). Some of these elastic domains were modified to contain lysine for cross linking purposes. The polymer also contained periodically spaced fibronectin CS5 domain enclosing the well known cell attachment sequence REDV. Finally, the polymer had target sequences for proteolitic action.Peer ReviewedAward-winnin

Structural behavior of cemented bahareque for social housing: A case study in Guayaquil City, Ecuador

The need for social housing creates challenges for engineering. One of the most economical and ecological structural systems for certain areas is the cemented bahareque, which uses Guadua cane, a type of Bamboo with favorable properties for construction. Despite being an ancient technique for the construction of houses, there is not an extensive bibliography that allows making justified decisions regarding their design in most cases. One of the objectives of this article is to present a prototypical design of a housing case with appropriate characteristics to allow a decent occupant’s life with this construction system. For the selected house, the structural behavior is evaluated under gravitational and seismic loads. The constructive criteria that will provide good performance under seismic events are recommended. The most important criteria to follow for the design of wall systems are regularity, continuity, symmetry, bolted connections, rigid diaphragms for mezzanines and continuous maintenance of the Guadua cane elements that make up the framework of the walls. Finally, it is concluded that following the basic criteria of earthquake-resistant design for this type of housing, adequate structural performance can be obtained

Constraining the X-ray reflection in low accretion rate AGN using XMM-Newton, NuSTAR and Swift

An interesting feature in active galactic nuclei (AGN) accreting at low rate is the weakness of the reflection features in their X-ray spectra, which can result from the gradual disappearance of the torus with decreasing accretion rates. It has been suggested that low luminosity AGN (LLAGN) would have a different reflector configuration compared with high luminosity AGN, either covering a smaller fraction of the sky or simply having less material. Additionally, we note that the determination of the spectral index ($\Gamma$) and the cut-off energy of the primary power-law emission is affected by the inclusion of reflection models, showing the importance of using them to study the accretion mechanism, especially in the case of the LLAGN that have previously shown a high dispersion on the relation between $\Gamma$ and the accretion rate. Our purpose is to constrain the geometry and column density of the reflector in a sample of LLAGN covering a broad X-ray range of energy combining data from XMM-Newton + NuSTAR + Swift of a hard X-ray-flux limited sample of 17 LLAGN from BASS/DR2 with accretion rates $\lambda_{Edd}$=L$_{\rm Bol}$/L$_{\rm Edd}$<10$^{-3}$. We fit all spectra using the reflection model for torus (borus02) and accretion disk (Xillver) reflectors. We found a tentative correlation between the torus column density and the accretion rate, LLAGN shows a lower column density compared with the high-luminosity objects. We also confirm the relation between $\Gamma$ and $\lambda_{Edd}$, with a smaller scatter than previously reported, thanks to the inclusion of high-energy data and the reflection models. Our results are consistent with a break at $\lambda_{Edd}\sim10^{-3}$, suggestive of a different accretion mechanism compared with higher accretion AGN.Comment: Accepted for publication in Astronomy & Astrophysic

New uses of treated urban waste digestates on stimulation of hydroponically grown tomato (Solanum lycopersicon L.)

One strategy to re-use solid urban wastes is the production of energy by anaerobic digestion. This process also generates high volume of digestates, which are frequently disposal in landfills. The aim of this work is to assess anaerobic digestates as agricultural inputs. Three different biomethanation wastes from different plants were collected. Firstly, a complete physico-chemical characterization of the wastes was done according to the Spanish regulation, showing that the materials had the 90% of the particles below 25 mm, high values of pH, electric conductivity, organic matter, humic acids and soluble nutrients such as NO3−, SO42−, Ca2+, Mg2+, PO43− and K+. Total concentrations of heavy metals and microbiological parameters were below the threshold levels allowed for agricultural use. The wastes were then treated with a strong acid and a strong base having two different solutions (ATr and BTr, respectively) which were evaluated as biostimulants for tomato plants in hydroponic culture. Those liquid extracts, ATr and BTr, demonstrated their biostimulant ability towards root system of tomato enhancing the hair root density and plant biometric parameters including plants weight and chlorophyll content. This work demonstrates the re-use feasibility of treated digestates in agriculture as fertilizers and more over as feedstock for biostimulants productio

Phosphoenolpyruvate from Glycolysis and PEPCK Regulate Cancer Cell Fate by Altering Cytosolic Ca2+

Changes in phosphoenolpyruvate (PEP) concentrations secondary to variations in glucose availability can regulate calcium signaling in T cells as this metabolite potently inhibits the sarcoplasmic reticulum Ca2+/ATPase pump (SERCA). This regulation is critical to assert immune activation in the tumor as T cells and cancer cells compete for available nutrients. We examined here whether cytosolic calcium and the activation of downstream effector pathways important for tumor biology are influenced by the presence of glucose and/or cataplerosis through the phosphoenolpyruvate carboxykinase (PEPCK) pathway, as both are hypothesized to feed the PEP pool. Our data demonstrate that cellular PEP parallels extracellular glucose in two human colon carcinoma cell lines, HCT-116 and SW480. PEP correlated with cytosolic calcium and NFAT activity, together with transcriptional up-regulation of canonical targets PTGS2 and IL6 that was fully prevented by CsA pre-treatment. Similarly, loading the metabolite directly into the cell increased cytosolic calcium and NFAT activity. PEP-stirred cytosolic calcium was also responsible for the calmodulin (CaM) dependent phosphorylation of c-Myc at Ser62, resulting in increased activity, probably through enhanced stabilization of the protein. Protein expression of several c-Myc targets also correlated with PEP levels. Finally, the participation of PEPCK in this axis was interrogated as it should directly contribute to PEP through cataplerosis from TCA cycle intermediates, especially in glucose starvation conditions. Inhibition of PEPCK activity showed the expected regulation of PEP and calcium levels and consequential downstream modulation of NFAT and c-Myc activities. Collectively, these results suggest that glucose and PEPCK can regulate NFAT and c-Myc activities through their influence on the PEP/Ca2+ axis, advancing a role for PEP as a second messenger communicating metabolism, calcium cell signaling, and tumor biology

Paleoseismological evidence of holocene activity of the Los Tollos fault (Murcia, se Spain): a lately formed quaternary tectonic feature of the eastern betic shear zone

The Los Tollos Fault is a recent and important feature of the Eastern Betic Shear Zone, one of the major tectonic structures in South Iberia accommodating the convergence between Nubian and Eurasian plates in the western Mediterranean. The Los Tollos Fault became active by the end of Middle Pleistocene introducing some paleogeographical modifications. Previously mapped as a secondary normal fault related to the Carrascoy Fault, recent research evidences that the Los Tollos Fault is an independent Holocene active left-lateral reverse fault extending for at least 15 km. Data analysis from 4 trenches dug across the fault has revealed the occurrence of at least two paleo-earthquake events during the Holocene. The most recent event is dated between 2,740 and 2,140 yr BP (8th to 2nd centuries BC). The size of the paleoevents is calculated to be Mw 6.3 – 6.6 following empirical regressions on surface rupture length. The recurrence interval is estimated to be between 2,200-6,860 years, fitting a slip rate for the fault between 0.12 and 0.17 mm/yr. Such parameters highlight the Los Tollos Fault as a tectonic structure with a considerable activity located relatively close to densely populated areas. These seismogenic parameters should be considered in future reassessments of the seismic hazard of the regionThis work forms part of the research activities carried out in the FASEGEO Project (CGL2009-09726) funded by the Spanish Ministry of Science and Innovatio

Comparison of Three-phase Active Rectifier Solutions for Avionic Applications: Impact of the Avionic Standard DO-160 F and Failure Modes

In aircraft applications, there has been an increasing trend related with the More Electric Aircraft (MEA), which results in rapid rise in the electrical power demand on-board. One of its goals lies in minimizing weight and volume of the electrical subsystem while maintaining good power quality and efficiency. The main purpose of this paper is to present and analyze an electrical design of a three-phase Boost rectifier, a three-phase Buck rectifier and a three-phase Vienna rectifier for output power level of 10 kW and compare them in terms of weight, volume, efficiency etc. Moreover, the design is obliged to comply with specific sections of DO-160 standard for avionic equipment with 230 VAC, 360-800 Hz grid conditions. Even though all proposed solutions satisfy the standard requirements, it will be shown that the Vienna rectifier has the lowest volume and not considering failure modes, the better solution overall. However, due to increased number of semiconductors and additional circuitry required for soft start-up, the Buck rectifier would prove to be the more robust solution failure-wise

Nuevos eventos deformacionales registrados en el Segmento SO de la Falla de Carrascoy (Murcia, España): implicaciones en el modelo de crecimiento

La Falla de Carrascoy es una falla de desgarre sinestral que forma parte del Corredor de Cizalla de las Béticas Orientales. Con dos segmentos solapados (SO y NE) controla el borde norte de la Sierra de Carrascoy y su articulación con la Depresión del Guadalentín. El segmento SO está formado por la zona de Falla de Algezares – Casas Nuevas, un sistema de pliegues y cabalgamientos que conforman relieves de tipo foreberg dispuestos en échelon, mostrando la migración progresiva de la deformación hacia el NO desde el frente montañoso controlado por la falla de desgarre sinestral (Falla de Carrascoy s.s.). Estudios previos sitúan el inicio de la formación de la Falla de Algezares – Casas Nuevas en el Pleistoceno medio. En el presente trabajo se han identificado nuevos eventos de deformación tectónica en el extremo NE de la falla que pliegan y cabalgan los sedimentos de abanicos aluviales del Pleistoceno superior. Estos eventos posteriores a los registrados en localizaciones más occidentales en los trabajos previos, se ajustan a un modelo de crecimiento en el que la longitud de la falla aumenta gradualmente con cada terremoto

New deformational events recorded in the SW Segment of the Carrascoy Fault (Murcia, Spain): Implications in the growth model

La Falla de Carrascoy es una falla de desgarre sinestral que forma parte del Corredor de Cizalla de las Béticas Orientales. Con dos segmentos solapados (SO y NE) controla el borde norte de la Sierra de Carrascoy y su articulación con la Depresión del Guadalentín. El segmento SO está formado por la zona de Falla de Algezares – Casas Nuevas, un sistema de pliegues y cabalgamientos que conforman relieves de tipo foreberg dispuestos en échelon, mostrando la migración progresiva de la deformación hacia el NO desde el frente montañoso controlado por la falla de desgarre sinestral (Falla de Carrascoy s.s.). Estudios previos sitúan el inicio de la formación de la Falla de Algezares – Casas Nuevas en el Pleistoceno medio. En el presente trabajo se han identificado nuevos eventos de deformación tectónica en el extremo NE de la falla que pliegan y cabalgan los sedimentos de abanicos aluviales del Pleistoceno superior. Estos eventos posteriores a los registrados en localizaciones más occidentales en los trabajos previos, se ajustan a un modelo de crecimiento en el que la longitud de la falla aumenta gradualmente con cada terremoto.The Carrascoy Fault is a left-lateral strike-slip fault belonging to the Eastern Betic Shear Zone. With two overlapping segments (SW and NE), this fault controls the northern edge of the Carrascoy Range and its linkage with of the Guadalentín Depression. The SW segment is formed by the Algezares – Casas Nuevas Fault zone, a fold-and-thrust system constituting foreberg-type, en-echelon-arranged reliefs that show the progressive northwestward migration of deformation from the front controlled by the left-lateral strike-slip (s.s. Carrascoy Fault). Prior studies locate the onset of the Algezares – Casas Nuevas Fault in the middle Pleistocene. In this paper we have identified new tectonic events at the NE fault tip, which fold and thrust the sediments of late Pleistocene alluvial fans. These events are younger than those recorded westernmost in previous studies, and they support a growth model in which the length fault gradually increases with each earthquake.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu