Un estudio sobre el papel clasificador de las garantías en los mercados de crédito con información asimétrica

This paper tests Bester's (1985, 1987) prediction about the separating role ofcontracts that involve both interest rates and collateral in credit markets. To test thisprediction we use data from natural credit markets and controlled experiments. Using asample of credits to small and medium size firms in Valencia, Spain, we relate twodifferent types of contracts with the ex post risk type of the borrower and other relevantvariables. We then design two incentive compatible contracts and analyze decisionsunder two different experimental treatments, one with moral hazard. Our empiricalresults confirm that borrowers of ex post lower risk choose contracts with highercollateral and lower interest rate. However, we find that moral hazard could reduceseparation. En este trabajo se examinan las tesis de Bester (1985, 1987) sobre el efecto clasificador de los contratos de préstamo que combinan los requisitos de garantía y tipo de interés. Para ello, empleamos dos métodos de análisis complementarios: un análisis empírico tradicional y un análisis experimental. En el primero, sobre una muestra de préstamos a Pymes de la Comunidad Valenciana, relacionamos dos tipos de contratos con el riesgo ex post del prestatario y otras variables relevantes del contrato y/o de la empresa. En el segundo, diseñamos dos contratos incentivo-compatibles y analizamos las elecciones de los individuos en dos entornos: con y sin riesgo moral. Nuestros resultados empíricos y experimentales confirman que los prestatarios de menor riesgo ex post se concentran en los contratos de mayor garantía y menor tipo de interés. Sin embargo, encontramos evidencia experimental de que la existencia de riesgo moral podría reducir la eficacia en la clasificación.Mercado de crédito, garantías, contratos incentivo-compatibles, información asimétrica, riesgo moral Credit markets, incentive compatible contracts, asymmetric information, moral hazard, experiments

Extended WKB method, resonances and supersymmetric radial barriers

Semiclassical approximations are implemented in the calculation of position and width of low energy resonances for radial barriers. The numerical integrations are delimited by t/T<<8, with t the period of a classical particle in the barrier trap and T the resonance lifetime. These energies are used in the construction of `haired' short range potentials as the supersymmetric partners of a given radial barrier. The new potentials could be useful in the study of the transient phenomena which give rise to the Moshinsky's diffraction in time.Comment: 12 pages, 4 figures, 3 table

Design and development of a dual-flow bioreactor mimicking intestinal peristalsis and permeability in epithelial tissue barriers for drug transport assessment.

we present a bioreactor system which combines a semi permeable membrane that simulates the osmotic nutrients interchange in the intestine circulation and rhythmic peristaltic movement. This custom-designed, pulsatile membrane bioreactor, with programmable manipulation, allows adjustment of luminal flow rate. In addition, this system is also capable of achieving the intestine-like drug distribution to the cells by the luminal perfusion of the hollow channel compartment. This dynamic platform can mimic the human intestine with increased accuracy to overcome many of the limitations with the previously described in vitro intestinal models, providing a more representative model of the human intestine

Plasma gradient modified scaffolds to generate a chemoattractant surface

A gradient of plasma polymerization of pyrrole was generated to model a chemoattractant surface; it was obtained by changing the polymerization time to manipulate the thickness and the deposited layer. The polymerization was generated with a power of 30W on a cylindrical vacuum reactor, the coverslip was polymerized covered by a cavity with a surface exposed of 0.7 cm every 35 min., the cells seeded were liver stellate cells (Ito); it was evaluated against a coverslip with continuous plasma polymerization of pyrrole (Ppy). The results show similar protein secretions, but cells proliferation was selective in the surface gradient regions

Optical potentials using resonance states in Supersymmetric Quantum Mechanics

Complex potentials are constructed as Darboux-deformations of short range, radial nonsingular potentials. They behave as optical devices which both refracts and absorbs light waves. The deformation preserves the initial spectrum of energies and it is implemented by means of a Gamow-Siegert function (resonance state). As straightforward example, the method is applied to the radial square well. Analytical derivations of the involved resonances show that they are `quantized' while the corresponding wave-functions are shown to behave as bounded states under the broken of parity symmetry of the related one-dimensional problem.Comment: 16 pages, 6 figures, 1 tabl

Elastofibroma Dorsi

Se realiza un estudio clínico-patológico de dos casos, mujeres de 57 y 45 años, de "elastofibroma dorsi" intervenidos quirúrgicamente. En una enferma apareció como una tumoracion asintomática y en otra asociada a dolor en el hombro irradiado a miembro superior derecho. Se describen las particularizadas clínicas, las exploraciones complementarias, los hallazgos quirúrgicos y las características histológicas de estos tumores de partes blandas cuyo origen debe referirse a una alteración del tejido fibroelástico. Se confronta nuestra experiencia con los casos anteriormente publicados confirmándose su aparición en mujeres adultas o añosas dedicadas a trabajos manuales rutinarios, que parecen estar implicados en la patogenia del elastofibroma dorsi. En uno de los casos, aunque localizado en el espacio anatómico escápulo-torácico, su situación era supraescapular frente a la típicamente infraescapular del elastofibroma dorsi, y la consideramos la primera observación de la literatura.A clinical-pathological study of two cases of elastofibroma dorsi was carried out. Both patients were female, 57 and 45 years old, and underwent surgical operation. One patients was sympton-free, while the other complained of pain in the shoulder which spread to the upper right arm. The autors describe the clinical details, the diagnostic methods employed, the results of surgery and the histopathological features of these tumours which must have originated in a modification of conective tissue, especially in elastic fibres. We compare our findings with those of previously published cases and can confirm the appearence of these tumours in adults or middle-aged women who carry out rutinary manual work, which seems to be connected with the pathogeny of the elastofibroma dorsi. These are normally found adjacent to the vertebral border of the escapula at its inferior angle, but in one case ot was located in the supra-escapular region and we believe this is the first evidence of this kind in the literature

Influence of Ca/Si ratio on the microstructure and properties of blended cements elaborated with kaolinite based waste

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1To reduce the environmental impact of cement industries, cementitious materials are added to the manufacture of eco-efficient cements, focusing in industrial wastes. In this paper metakaolinite (MK) based industrial wastes have been mixed with cement in order to study the effect of the chemical composition of the raw material in both microstructural and mechanical properties of the pastes. Frattini test was also determined. The selected metakaolin based industrial wastes were previously activated for two hours at temperatures around 600ºC to transform the inert waste into a cementing material. The industrial wastes materials used were coal mining and paper sludge. The second one was mixed with fly ash (50/50 w/w) in order to evaluate the performance of ternary blended cements. The mixtures were prepared with OPC and both 6 and 20% of activated industrial waste (coal mining and paper sludge + fly ash). Prismatic samples (1x1x6 cm) were prepared with water/cement ratio of 0.5 and cured 28 days. After this time, mineralogical composition of the samples was determined by XRD as well as mechanical properties (compressive and flexural strength, total porosity, etc). Besides, portlandite and ettringite, both monocarboaluminate and C4AH13 have been formed in the samples after 28 days of hydration. It can be observed that C4AH13 decreases as Ca/Si ratio decreases; with the opposite behaviour for the monocarboaluminate. From the mechanical properties, porosity decreases from 1 to 28 days of curing as compressive strength increases.To the Ministry of Economy and Competiveness by the financial support (MAT2012-37005-C03-01-02-03).Peer Reviewe

Non-Hermitian SUSY Hydrogen-like Hamiltonians with real spectra

It is shown that the radial part of the Hydrogen Hamiltonian factorizes as the product of two not mutually adjoint first order differential operators plus a complex constant epsilon. The 1-susy approach is used to construct non-hermitian Hamiltonians with hydrogen spectra. Other non-hermitian Hamiltonians are shown to admit an extra `complex energy' at epsilon. New self-adjoint hydrogen-like Hamiltonians are also derived by using a 2-susy transformation with complex conjugate pairs epsilon, (c.c) epsilon.Comment: LaTeX2e file, 13 pages, 6 EPS figures. New references added. The present is a reorganized and simplified versio

Silver nanoparticle chains for ultra-long-range plasmonic waveguides for Nd3+ fluorescence

Plasmonic waveguides have been shown to be a promising approach to confine and transport electromagnetic energy beyond the diffraction limit. However, ohmic losses generally prevent their integration at micrometric or millimetric scales. Here, we present a gain-compensated plasmonic waveguide based on the integration of linear chains of Ag nanoparticles on an optically active Nd3+-doped solid-state gain medium. By means of dual confocal fluorescence microscopy, we demonstrate long-range optical energy propagation due to the near-field coupling between the plasmonic nanostructures and the Nd3+ ions. The subwavelength fluorescence guiding is monitored at distances of around 100 µm from the excitation source for two different emission ranges centered at around 900 nm and 1080 nm. In both cases, the guided fluorescence exhibits a strong polarization dependence, consistent with the polarization behavior of the plasmon resonance supported by the chain. The experimental results are interpreted through numerical simulations in quasi-infinite long chains, which corroborate the propagation features of the Ag nanoparticle chains at both excitation (λexc = 590 nm) and emission wavelengths. The obtained results exceed by an order of magnitude that of previous reports on electromagnetic energy transport using linear plasmonic chains. The work points out the potential of combining Ag nanoparticle chains with a small interparticle distance (~2 nm) with rare-earth-based optical gain media as ultra-long-range waveguides with extreme light confinement. The results offer new perspectives for the design of integrated hybrid plasmonic–photonic circuits based on rare-earth-activated solid-state platformsThis research has been funded by the Spanish State Research Agency under contracts PID2019-108257GB-I00 and RTI2018-098452-B-100, Comunidad de Madrid under contract CAM (SI1/PJI/2019-00105) and the María de Maeztu “Programme for Units of Excellence in R&D” CEX2018-000805-

Experimental evidence of charged domain walls in lead-free ferroelectric ceramics: Light-driven nanodomain switching

The control of ferroelectric domain walls at the nanometric level leads to novel interfacial properties and functionalities. In particular, the comprehension of charged domain walls, CDWs, lies at the frontier of future nanoelectronic research. Whereas many of the effects have been demonstrated for ideal archetypes, such as single crystals, and/or thin films, a similar control of CDWs on polycrystalline ferroelectrics has not been achieved. Here, we unambiguously show the presence of charged domain walls on a lead-free (K,Na)NbO 3 polycrystalline system. The appearance of CDWs is observed in situ by confocal Raman microscopy and second harmonic generation microscopy. CDWs produce an internal strain gradient within each domain. Specifically, the anisotropic strain develops a crucial piece in the ferroelectric domain switching due to the coupling between the polarization of light and the ferroelectric polarization of the nanodomain in the (K,Na)NbO 3 ceramic. This effect leads to the tuning of the ferroelectric domain switching by means of the light polarization angle. Our results will help to understand the relevance of charged domain walls on the ferroelectric domain switching process and may facilitate the development of domain wall nanoelectronics by remote light control utilizing polycrystalline ferroelectricsThis work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the projects MAT201348009-C4-1-P, MAT2013-43301-R and MAT2016-76106-R, the Spanish National Research Council (CSIC) under the project NANOMIND CSIC 201560E068 and the Comunidad de Madrid under the grant S2013/MIT-274