Sobre la libertad y las diversas expresiones de la cultura que, acrecentadas por la mirada profunda de la fe, iluminan los interrogantes de nuestro tiempo

Resumen: Promover el diálogo de la Iglesia con las culturas de nuestro tiempo resulta inobjetable. El Concilio Ecuménico Vaticano II se pronunció en este sentido, en comunión histórica con distintas civilizaciones, hace ya medio siglo; asimismo, destacó la necesidad para los creyentes de comprender a fondo la manera de pensar y de sentir de los demás hombres de la propia época, y dedicó a esta temática toda una sección de la Constitución Pastoral Gaudium et spes. El campo de la economía, bajo esta idea, hubo de subsumirse con carácter sistemático a un estrecho criterio de racionalidad, según el cual tanto la acción humana individual como la política a nivel general se consideraron determinadas por cálculos y valoraciones de costos y beneficios a través de un juicio de optimización.

La buena fe y su aplicación en el derecho argentino

Al leer nuestro Código Civil –y legislación en general–, encontramos muchas veces en el articulado el término “buena fe”, al cual por lo general no analizamos en profundidad, dado que lo consideramos como algo que está sobreentendido, o que tal vez no necesite definirse. Ahora bien, ¿cuál es el significado del mismo?, ¿qué aplicación tiene en nuestro ordenamiento jurídico?, ¿sigue vigente en el nuevo Anteproyecto de Código Civil y Comercial de la Nación? Son las preguntas que intentaremos respondernos a lo largo de este artículo.

El obrar divino en la historia como objeto de fe : Benedicto XVI y Santo Tomás de Aquino

Introducción: A lo largo de su obra, J. Ratzinger ha destacado la dimensión histórica de la revelación divina como un rasgo esencial de la religión de Israel y, de un modo específico, de la fe cristiana. En las últimas décadas el hoy Papa Benedicto XVI ha renovado esta afirmación, ante interpretaciones que correrían el riesgo de oscurecer dicha dimensión del obrar divino como objeto de fe. Sus expresiones recientes podrían ponerse en relación con otras tempranas sobre santo Tomás de Aquino, al compararlo con representantes de la tradición platónico-agustiniana, como san Buenaventura. En esta presentación haremos referencia sucesivamente a algunas de dichas observaciones tempranas de J. Ratzinger, a la vinculación entre el misterio de Dios y obrar divino en la creación y en la historia en algunos textos del Aquinate, y a expresiones más recientes de Benedicto XVI, que permiten percibir un cierto diálogo subyacente con sus fuentes, así como la actualidad del tema.

Fe, cristianismo y humildad: núcleos teologales de la pastoral popular del padre Rafael Tello

Resumen: Sin pretender “espiritualizar” la teología del padre Rafael Tello, este artículo ofrece algunas de las vertientes en las que abreva la espiritualidad de la pastoral popular de la que el teólogo argentino es uno de sus más originales representantes. Indagaremos en ciertos núcleos teologales y teológicos que nos permitirán registrar una continuidad entre teología y vida, al tiempo que nos dejarán en el umbral de una propuesta evangelizadora que no es posible comprender sin esta manera de vivir la fe cristiana. De la mano de figuras tradicionales de la mística y de la teología como san Juan de la Cruz y santo Tomás de Aquino, el padre Tello nos propone recrear la vivencia del evangelio para los tiempos actuales.

Fe y teología : elogio de la via eminentiae

Resumen: Este texto muestra la importancia de la conversión como parte esencial de la tarea pensante de la teología a la hora de la Nueva Evangelización. El autor relaciona la eficacia de la palabra teológica en diálogo con la actual cultura posmoderna, con la exigencia –para la teología– de superar críticamente sus propias posibles idolatrías, entrando decidida y gozosamente en la via eminentiae, en el camino incesante hacia el “Dios siempre mayor”, que es, a la vez, el camino hacia lo auténticamente humano. El itinerario del apóstol Pedro ilustra ejemplarmente el planteo que propone el autor.

铁基抗高温磨损激光熔覆涂层强韧设计和研究 Ⅱ:Fe-Cr-C-W-Ni激光熔覆层的微观组织及性能

利用ＯＭ、ＳＥＭ、ＴＥＭ研究了Ｆｅ－Ｃｒ－Ｃ－Ｗ－Ｎｉ激光熔覆涂层熔覆态及其高温时效态的微观组织结构。结果表明激光熔覆层组织细小，具有强韧两相组成（奥氏体和Ｍ_７Ｃ_３碳化物）的微观结构特征，高温时效处理组织中有Ｍ_（２３）Ｃ_６、Ｍ_６Ｃ、Ｍ_２Ｃ等新碳化物形成。显微硬度和冲击磨损实验证实了激光熔覆态和峰值时效态熔覆层均具有良好的力学性能。

DNA Damage and Transcriptional Changes in the Gills of Mytilus galloprovincialis Exposed to Nanomolar Doses of Combined Metal Salts (Cd, Cu, Hg)

[ENG]Aiming at an integrated and mechanistic view of the early biological effects of selected metals in the marine sentinel organism Mytilus galloprovincialis, we exposed mussels for 48 hours to 50, 100 and 200 nM solutions of equimolar Cd, Cu and Hg salts and measured cytological and molecular biomarkers in parallel. Focusing on the mussel gills, first target of toxic water contaminants and actively proliferating tissue, we detected significant dose-related increases of cells with micronuclei and other nuclear abnormalities in the treated mussels, with differences in the bioconcentration of the three metals determined in the mussel flesh by atomic absorption spectrometry. Gene expression profiles, determined in the same individual gills in parallel, revealed some transcriptional changes at the 50 nM dose, and substantial increases of differentially expressed genes at the 100 and 200 nM doses, with roughly similar amounts of up- and down-regulated genes. The functional annotation of gill transcripts with consistent expression trends and significantly altered at least in one dose point disclosed the complexity of the induced cell response. The most evident transcriptional changes concerned protein synthesis and turnover, ion homeostasis, cell cycle regulation and apoptosis, and intracellular trafficking (transcript sequences denoting heat shock proteins, metal binding thioneins, sequestosome 1 and proteasome subunits, and GADD45 exemplify up-regulated genes while transcript sequences denoting actin, tubulins and the apoptosis inhibitor 1 exemplify down-regulated genes). Overall, nanomolar doses of co-occurring free metal ions have induced significant structural and functional changes in the mussel gills: the intensity of response to the stimulus measured in laboratory supports the additional validation of molecular markers of metal exposure to be used in Mussel Watch programs

Trace metals in fresh water plankton

The uptake of Cu, Zn, and Cd by fresh water plankton was studied by analyzing samples of water and plankton from six lakes in southern California. Co, Pb, Mn, Fe, Na, K, Mg, Ca, Sr, Ba, and Al were also determined in the plankton samples. Special precautions were taken during sampling and analysis to avoid metal contamination.

The relation between aqueous metal concentrations and the concentrations of metals in plankton was studied by plotting aqueous and plankton metal concentrations vs time and comparing the plots. No plankton metal plot showed the same changes as its corresponding aqueous metal plot, though long-term trends were similar. Thus, passive sorption did not completely explain plankton metal uptake.

The fractions of Cu, Zn, and Cd in lake water which were associated with plankton were calculated and these fractions were less than 1% in every case.

To see whether or not plankton metal uptake could deplete aqueous metal concentrations by measurable amounts (e.g. 20%) in short periods (e.g. less than six days), three integrated rate equations were used as models of plankton metal sorption. Parameters for the equations were taken from actual field measurements. Measurable reductions in concentration within short times were predicted by all three equations when the concentration factor was greater than 10^5. All Cu concentration factors were less than 10^5.

The role of plankton was regulating metal concentrations considered in the context of a model of trace metal chemistry in lakes. The model assumes that all particles can be represented by a single solid phase and that the solid phase controls aqueous metal concentrations. A term for the rate of in situ production of particulate matter is included and primary productivity was used for this parameter. In San Vicente Reservoir, the test case, the rate of in situ production of particulate matter was of the same order of magnitude as the rate of introduction of particulate matter by the influent stream.

Part I. Kinetics of coarsening of the gamma-prime precipitate in nickel-silicon alloys. Part II. Rate of crystallization of an amorphous Fe-P-C alloy

The coarsening kinetics of Ni₃ Si(γ') precipitate in a binary Ni-Si alloy containing 6.5 wt. % silicon was studied by magnetic techniques and transmission electronmicroscopy. A calibration curve was established to determine the concentration of silicon in the matrix. The variation of the Si content of the Ni-rich matrix as a function of time follows Lifshitz and Wagner theory for diffusion controlled coarsening phenomena. The estimated values of equilibrium solubility of silicon in the matrix represent the true coherent equilibrium solubilities.

The experimental particle-size distributions and average particle size were determined from dark field electron micrographs. The average particle size varies linearly with t^-1/3 as suggested by Lifshitz and Wagner. The experimental distributions of particle sizes differ slightly from the theoretical curve at the early stages of aging, but the agreement is satisfactory at the later stages. The values of diffusion coefficient of silicon, interfacial free energy and activation energy were calculated from the results of coarsening kinetics. The experimental value of effective diffusion coefficient is in satisfactory agreement with the value predicted by the application of irreversible the rmodynamics to the process of volume constrained growth of coherent precipitate during coarsening. The coherent γ' particles in Ni-Sialloy unlike those in Ni-Al and Ni-Ti seem to lose coherency at high temperature. A mechanism for the formation of semi-coherent precipitate is suggested.

Prescription for optimizing holograms in LiNbO3 : Fe : Mn

The photorefractive holographic dynamics of grating formation in photochromic doubly doped LiNbO3:Fe:Mn crystal is studied numerically and analytically in terms of the two-center model of Kukhtarev Et al. [Ferroelectrics 22, 949 (1979)]. The relations among the recorded and fixed space-charge fields and the doping densities, the oxidation-reduction states of the fields, and the intensities of UV-sensitizing and red recording beams are studied. Important conditions and effects are feued, and an optimal prescription for material doping and oxidation-reduction processing is suggested in which the crystal can be strongly oxidized and the Mn-doping density is smaller than the Fe-doping density. (C) 2000 Optical Society of America. OCIS codes: 050.7330, 190.5330, 090.2900.

Absorption characteristic and nonvolatile holographic recording in LiNbO3 : Cr : Cu crystals

The absorption characteristic of lithium niobate crystals doped with chromium and copper (Cr and Cu) is investigated. We find that there are two apparent absorption bands for LiNbO3:Cr:Cu crystal doped with 0.14 wt.% Cr2O3 and 0.011 wt.% CuO; one is around 480 nm, and the other is around 660 nm. With a decrease in the doping composition of Cr and an increase in the doping composition of Cu, no apparent absorption band in the shorter wavelength range exists. The higher the doping level of Cr, the larger the absorbance around 660 nm. Although a 633 nm red light is located in the absorption band around 660 nm, the absorption at 633 nm does not help the photorefractive process; i.e., unlike other doubly doped crystals, for example, LiNbO3:Fe:Mn crystal, a nonvolatile holographic recording can be realized by a 633 nm red light as the recording light and a 390 nm UV light as the sensitizing light. For LiNbO3:Cr:Cu crystals, by changing the recording light from a 633 nm red light to a 514 nm green light, sensitizing with a 390 nm UV light and a 488 nm blue light, respectively, a nonvolatile holographic recording can be realized. Doping the appropriate Cr (for example, N-Cr = 2.795 X 10(25)m(-3) and N-Cr/N-Cu = 1) benefits the improvement of holographic recording properties. (c) 2005 Optical Society of America.

Improvement of sensitivity and refractive-index changes in LiNbO3 : Ce : Cu crystals with UV light

A nonvolatile recording scheme is proposed using LiNbO3:Ce:Cu crystals and modulated UV light to record gratings simultaneously in two centres and using red light to bleach the grating in the shallow centre to realize persistent photorefractive holographic storage. Compared with the normal UV-sensitized nonvolatile holographic system, the amplitude of refractive-index changes is greatly increased and the recording sensitivity is significantly enhanced by recording with UV light in the LiNbO3:Ce:Cu crystals. Based on jointly solving the two-centre material equations and the coupled-wave equations, temporal evolutions of the photorefractive grating and the diffraction effciency are effectively described and numerically analysed. Roles of doping levels and recording-beam intensity are discussed in detail. Theoretical results confirm and predict experimental results.

Sensitivity improvement by UV-light recording in LiNbO3 : Ce : Cu crystals

Modulated UV light is used to increase the sensitivity of the two-centre holographic recording. Inherent mechanisms of nonvolatile holographic recording in oxidized and reduced crystals are numerically analysed based on solving the two-centre material equations modilied for UV-Iight recording. Experiments verification is performed with an oxidized crystal and a reduced crystal, and the role of UV intensity on the sensitivity is presented.

Mass measurements of some proton-rich nuclei

The Q values and 0^o cross sections of (He³, n) reactions forming seven proton-rich nuclei have been measured with accuracies varying from 6 to 18 keV. The Q values (in keV) are: Si²⁶ (85), S³⁰ (-573), Ar³⁴ (-759), Ti⁴² (-2865), Cr⁴⁸ (5550), Ni⁵⁶ (4513) and Zn⁶⁰ (818). At least one excited state was found for all but Ti⁴². The first four nuclei complete isotopic spin triplets; the results obtained agree well with charge-symmetry predictions. The last three, all multiples of the α particle, are important in the α and e-process theories of nucleo-synthesis in stars. The energy available for β decay of these three was found by magnetic spectrometer measurements of the (He³, p) Q values of reactions leading to V⁴⁸, Co⁵⁶, and Cu⁶⁰. Many excited states were seen: V⁴⁸ (3), Co⁵⁶ (15), Cu⁶⁰ (23). The first two states of S³⁰ are probably 0⁺ and 2⁺ from (He³, n) angular distribution measurements. Two NaI γ-ray measurements are described: the decay of Ar³⁴ (measured ^Ƭ1/2 = 1.2 ± 0.3s) and the prompt γ-ray spectrum from Fe⁵⁴(He³, nγ)Ni⁵⁶. Possible collective structure in Ni⁵⁶ and Ca⁴⁰, both doubly magic, is discussed.

The (He³, n) neutron energy and yield measurements utilized neutron-induced nuclear reactions in a silicon semiconductor detector. Cross sections for the most important detection processes, Si²⁸ (n, α) Mg²⁵ and Si²⁸ (n, p) Al²⁸, are presented for reactions leading to the first four states of both residual nuclei for neutron energies from 7.3 to 16.4 MeV. Resolution and pulse-height anomalies associated with recoil Mg²⁵ and Al²⁸ ions are discussed. The 0^o cross section for Be⁹ (α, n) C¹², used to provide calibration neutrons, has been measured with a stilbene spectrometer for n_o (5.0 ≤ E_α ≤ 12 MeV), n₁ (4.3 ≤ E_α ≤ 12.0 MeV) and n₂ (6.0 ≤ E_α ≤ 10.1 MeV). Resonances seen in the n_o yield may correspond to nine new levels in C¹³.

Sistemas SCR y NSR-SCR para DeNOx en corrientes de escape diésel: Formulaciones, cinética y modelización

314 p.