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We present an autonomous system that remotely monitors the state of reinforced concrete structures. This system performs real-time follow-up of the corrosion rate of rebars (iCORR), along with other relevant parameters such as temperature, corrosion potential (ECORR), and electrical resistance of concrete (RE), at many of a structure’s control points by using embedded sensors. iCORR is obtained by applying a novel low-stress electrochemical polarization technique to corrosion sensors. The custom electronic system manages the sensor network, consisting of a measurement board per control point connected to a central single-board computer in charge of processing measurement data and uploading results to a server via 4G connection. In this work, we report the results obtained after implementing the sensor system into a reinforced concrete wall, where two well-differentiated representative areas were monitored. The obtained corrosion parameters showed consistent values. Similar conclusions are obtained with ECORR recorded in rebars. With the iCORR follow-up, the corrosion penetration damage diagram is built. This diagram is particularly useful for identifying critical events during the corrosion propagation period and to be able to estimate structures’ service life. Hence, the system is presented as a useful tool for the structural maintenance and service life predictions of new structures.

OptiGUI DataCollector is a Python 3.8-based graphical user interface that facilitates automated data collection in optics and photonics research and development equipment. It provides an intuitive and easy-to-use platform for controlling a wide range of optical instruments, including spectrometers and lasers. OptiGUI DataCollector is a flexible and modular framework that enables simple integration with different types of devices. It simplifies experimental workflow and reduces human error by automating parameter control, data acquisition, and analysis. OptiGUI DataCollector is currently focused on optical mode conversion utilizing fiber optic technologies but can be expanded to other R&D processes.

Mode division multiplexing (MDM) is currently one of the most attractive multiplexing techniques in optical communications, as it allows for an increase in the number of channels available for data transmission. Optical modal converters are one of the main devices used in this technique. Therefore, the characterization and improvement of these devices are of great current interest. In this work, we present a dataset of 49,736 near-field intensity images of a modal converter based on a long-period fiber grating (LPFG) written on a few-mode fiber (FMF). This characterization was performed experimentally at various wavelengths, polarizations, and temperature conditions when the device converted from LP01 mode to LP11 mode. The results show that the modal converter can be tuned by adjusting these parameters, and that its operation is optimal under specific circumstances which have a great impact on its performance. Additionally, the potential application of the database is validated in this work. A modal decomposition technique based on the particle swarm algorithm (PSO) was employed as a tool for determining the most effective combinations of modal weights and relative phases from the spatial distributions collected in the dataset. The proposed dataset can open up new opportunities for researchers working on image segmentation, detection, and classification problems related to MDM technology. In addition, we implement novel artificial intelligence techniques that can help in finding the optimal operating conditions for this type of device.

This work aims to study the corrosion performance of six concretes in the marine environment: three ordinary concretes (C30, C40 and C50); one high-performance concrete (C90); two ultra high-performance concretes, one without fibres (C150-NF) and another one with steel fibres (C150-F). To this end, porosity and chloride ingress resistance were analysed at different ages. Resistivity was also evaluated and the corrosion rate in the embedded rebars was monitored. The results showed that C30, C40 and C50 had porosity accessible to water percentages and capillary absorption values between six- and eight-fold higher than C90 and C150-NF and C150-F, respectively. Similar differences were obtained when oxygen permeability was analysed. Chloride ingress resistance in the ordinary concretes was estimated to be one-fold lower than in C90 and two-fold lower than in C150-NF and C150-F. Presence of fibres in C150-F increased the diffusion coefficient between 5% and 50% compared to C150-NF. Fibres also affected resistivity: C150-NF had values above 5500 Ωm, but the C150-F and C90 values were between 700 and 1000 Ωm and were one-fold higher than the ordinary concretes. After 3 years, the corrosion damage in the embedded rebars exposed to a marine environment was negligible in C90, C150-NF and C150-F (9.5, 6.2 and 3.5 mg mass loss), but with higher values (between 170.4 and 328.9 mg) for C3, C40 and C50. The results allow a framework to be established to make comparisons in future studies.

Multisystem inflammatory syndrome in children (MIS-C) onsets in COVID-19 patients with manifestations similar to Kawasaki disease (KD). Here the author probe the peripheral blood transcriptome of MIS-C patients to find signatures related to natural killer (NK) cell activation and CD8+ T cell exhaustion that are shared with KD patients.

Matthew M. Hernandez and Ana S. Gonzalez-Reiche and colleagues report evidence of SARSCoV-2 infections in respiratory pathogen-negative nasopharyngeal specimens collected in New York, which date back to over one month before the first officially documented case in the state. The findings provide insights in to the origins of the virus in New York.

En este artículo discuto sobre la forma en cómo han cambiado las prácticas consumistas y, en consecuencia, la publicidad. La publicidad contemporánea tiene el objetivo de que los consumidores desarrollen fidelidad a la marca a través de las emociones y la creación de conexiones. Sostengo la idea de que las modas culturales fortalecen el capitalismo de consumo y las prácticas consumistas a pesar de que algunas de ellas intentan oponerse y denunciar las consecuencias nocivas de la vida consumista. Analizo cómo las formas de resistencia contracutlural son convertidas en mercancías y cómo las actitudes consumistas se generalizan y son aceptadas dócilmente hasta por los más fuertes opositores al capitalismo de consumo. Al final planteo que la indignación es el último recurso para reaccionar contra el capitalismo de consumo. Para ilustrar los argumentos ofrezco diversos ejemplos de cómo todo esto ocurre en la vida cotidiana.

Presentado en sesión de 22 de mayo de 1957

La sociedad de Cirugía realizó el 31 de octubre de 1951 una sesión homenaje a Profesor Domingo Prat

Presentado en sesión noviembre 1945. Incluye discursos de Armando Loubejac, Carlos Stajano, Fernando Etchegorry

Presentado en la Sesión del miércoles 23 de abril de 1946.

Presentado en sesión de 3 de mayo de 1944

Presentado en sesión de 12 de mayo de 1943

Obituario y homenaje al Ex presidente de la Sociedad de Cirugía

Presentado en sesión de 12 de agosto de 1942

The monitoring of concrete carbonation takes an important role in the structures maintenance, considering that corrosion induced by this phenomenon is one of the mainly failure causes in the Reinforcement Concrete Structures (RCS) located in industrial zones, roads and cities. Carbonation of concrete is produced by the penetration of the CO2 inside of the porous net, which is mainly combined with the Ca(OH)2 contained in the concrete pore solution producing carbonates with low solubility and eventually causing a pH drop until neutral levels. The pH drop produces the instability and final generalised destruction of the rebars passive layers, which is the step that precedes generalized corrosion. The current existing systems to detect concrete carbonation are based on potentiometric sensors to detect the pH of concrete pore solution. These have some limitations such as the interference of different reactions on the sensor surface. Considering these limitations, in this study a novel system of voltammetric Au sensors embedded in concrete for the detection of concrete carbonation was presented. In the voltammetric sensor, the potential sweep signal applied comprises the potential range where the effect of the pH variations has more influence in the sensor response. Then the response processing by means of the multivariate analysis PCA (principal component analysis) allows to manage a huge quantity of variables and to reduce the effect of the interference with other analytes, increasing the importance of the pH changes effect in the obtained data. Thus, increasing the reliability of the system to detect the concrete carbonation.

Sesión del 21 de Noviembre de 1934.

Presentado en la sesión del 8 de Junio de 1932

This work analyzes chemical surface and optical characteristics of a commercial nanoporous alumina structure (NPAS) as a result of surface coverage by different imidazolium-based ionic liquids (1-butyl-3-metylimidazolium hexafluorophosphate, 3-methyl-1-octylimidazolium hexafluorophosphate, or 1-ethyl-3-methylimidazolium tetrafluoroborate). Optical characteristics of the IL/NPAS samples were determined by photoluminescence (at different excitation wavelengths (from 300 nm to 400 nm), ellipsometry spectroscopy, and light transmittance/reflectance measurements for a range of wavelengths that provide information on modifications related to both visible and near-infrared regions. Chemical surface characterization of the three IL/NPAS samples was performed by X-ray photoelectron spectroscopy (XPS), which indicates almost total support coverage by the ILs. The IL/NPAS analyzed samples exhibit different photoluminescence behavior, high transparency (

This study aimed to remove carbamazepine from aqueous solutions, using functional silica phenylamine (SiBN), which is characterized and showed excellent chemical and thermal stability. Adsorbents based on silica were developed due to their unusually large surface area, homogenous pore structure, and well-modified surface properties, as silica sparked tremendous interest. It was determined to develop a novel silica adsorbent including phenylamine and amide (SiBCON). The adsorbents obtained were analyzed by various spectroscopy devices, including SEM, FT-IR and TGA analysis. The maximum removal rates for carbamazepine were 98.37% and 98.22% for SiBN and SiBCON, respectively, when optimized at room temperature, pH 9.0, initial concentration of 10 mg·L−1 and contact time of 15 min. Theoretical tools are widely used in the prediction of the power of interactions between chemical systems. The computed data showed that new amine modified silica is quite effective in terms of the removal of carbamazepine from aqueous solution. Calculation binding energies and DFT data showed that there is a powerful interaction between amine-modified silica and carbamazepine.

Medir el contenido de humedad (CH) de los agregados de concreto (ADC) en la fabricación de concreto premezclado es uno de los retos actuales en la industria de la construcción porque afecta a las propiedades finales del concreto. Actualmente los métodos que se utilizan para medir el CH en ADC son invasivos y destructivos. Este artículo presenta una técnica moderna basada en espectroscopía dieléctrica (ED), un método que al propagar microondas en el material correlaciona su constante dieléctrica (CD) y su CH. En esta investigación se ha utilizado este método en ADC. Tres diferentes canteras peruanas de ADC (Moyobamba, Sol-Sol y Cerro Mocho) han sido utilizadas. Los resultados demuestran que el sensor a una frecuencia de 1.5 GHz es capaz de detectar el CH en ADC con una regresión lineal de R2 = 95 %. En conclusión, se puede utilizar la ED como un método de sensado no invasivo y en línea de CH en ADC para ser utilizado en la industria de la construcción.

Abstract Decellularized vascular scaffolds are promising materials for vessel replacements. However, despite the natural origin of decellularized vessels, issues such as biomechanical incompatibility, immunogenicity risks and the hazards of thrombus formation, still need to be addressed. In this study, we coated decellularized vessels obtained from porcine carotid arteries with poly (ethylmethacrylate-co-diethylaminoethylacrylate) (8g7) with the purpose of improving endothelial coverage and minimizing platelet attachment while enhancing the mechanical properties of the decellularized vascular scaffolds. The polymer facilitated binding of endothelial cells (ECs) with high affinity and also induced endothelial cell capillary tube formation. In addition, platelets showed reduced adhesion on the polymer under flow conditions. Moreover, the coating of the decellularized arteries improved biomechanical properties by increasing its tensile strength and load. In addition, after 5 days in culture, ECs seeded on the luminal surface of 8g7-coated decellularized arteries showed good regeneration of the endothelium. Overall, this study shows that polymer coating of decellularized vessels provides a new strategy to improve re-endothelialization of vascular grafts, maintaining or enhancing mechanical properties while reducing the risk of thrombogenesis. These results could have potential applications in improving tissue-engineered vascular grafts for cardiovascular therapies with small caliber vessels.

Vibrational wavenumbers of pyridine adsorbed on a silver electrode have been correlated to the calculated ones from different theoretical approaches based on DFT methods. The vibrational tuning caused by the electrode potential has been simulated by means of pyridine-silver clusters with different densities of charge or, alternatively, under applied external electric fields. Both methodologies predict correctly a qualitative red-shift of the vibrational wavenumbers at negative potentials. As a result, harmonic frequency calculations performed at the B3LYP/LanL2DZ level of theory by using a linear [AgnPy]q complex model with different densities of charge (qeff = q/n) have exhibited the best agreement with the experimental observations although the tuning amplitudes are overestimated. Electric fields calculations are unable to account for subtle details observed in the spectra related to the differentiated chemical nature of the metal-molecule bond at positive or negative potentials with respect to the potential of zero charge of the electrode.

The present work presents the results obtained with a stainless steel (SS) voltammetric sensor to detect variations in humidity (H2O) and oxygen (O2) availability in concretes. First, studies in solution were run by preparing several solutions to represent the different conditions that can be found in concrete pores. Second, the sensor’s response was studied by varying O2 availability by argon or synthetic air bubbling. Then concrete conditions with different degrees of carbonation were simulated using solutions with a pH between 13 and 8.45. After characterization in solution, a study by means of concrete samples with several water/cement ratios (0.6, 0.5 and 0.4) was performed, in which sensors were embedded and studied under different O2 and H2O saturation conditions. The obtained results revealed that with the voltagram, it is possible to evaluate O2 availability variation from the slopes of the lines identified logarithmically in the voltagram for the obtained cathodic sweeping. All the results obtained with the sensor were correlated/validated by standard assays to characterize porosity in hardened concretes.

The concrete electrical resistivity is a prominent parameter in structural health monitoring, since, along with corrosion potential, it provides relevant qualitative diagnosis of the reinforcement corrosion. This study proposes a simple expression to reliable determine resistivity from the concrete electrical resistance (RE) provided by the corrosion sensor of the Integrated Network of Sensors for Smart Corrosion Monitoring (INESSCOM) we have developed. The novelty here is that distinct from common resistivity sensors, the cell constants obtained by the proposed expression are intended to be valid for any sensor implementation scenario. This was ensured by studying most significant geometrical features of the sensor in a wide set of calibration solutions. This embedded-sensor approach is intended to be applicable for RE measurements obtained both using potential step voltammetry (PSV, used in the INESSCOM sensor for corrosion rate measurement) and alternating current methods. In this regard, we present a simple protocol to reliably determine RE, and therefore resistivity, from PSV measurements. It consists in adding a very short potentiostatic pulse to the original technique. In this way, we are able to easy monitor resistivity along with corrosion rate through a single sensor, an advantage which is not usual in structural health monitoring.

The main objective of this study was to analyze the influence that the addition of finely ground hydrated lime has on chloride-induced reinforcement corrosion in eco-efficient concrete made with 50% cement replacement by fly ash. Six tests were carried out: mercury intrusion porosimetry, chloride migration, accelerated chloride penetration, electrical resistivity, and corrosion rate. The results show that the addition of 10–20% of lime to fly ash concrete did not affect its resistance to chloride penetration. However, the cementitious matrix density is increased by the pozzolanic reaction between the fly ash and added lime. As a result, the porosity and the electrical resistivity improved (of the order of 10% and 40%, respectively), giving rise to a lower corrosion rate (iCORR) of the rebars and, therefore, an increase in durability. In fact, after subjecting specimens to wetting–drying cycles in a 0.5 M sodium chloride solution for 630 days, corrosion is considered negligible in fly ash concrete with 10% or 20% lime (iCORR less than 0.2 µA/cm2), while in fly ash concrete without lime, corrosion was low (iCORR of the order of 0.3 µA/cm2) and in the reference concrete made with Portland cement, only the corrosion was high (iCORR between 2 and 3 µA/cm2).

Este texto trata sobre los usos sociales de las imágenes. Está dividido en cuatro apartados. Se asume una idea central: las imágenes no poseen significados propios si no es gracias a la intermediación de las dimensiones sociales, ideológicas, políticas, culturales, etc., que perfilan un ‘modo de ver’. Se sostiene que las imágenes nunca están solas y que establecemos lazos sociales con ellas gracias a las formas en que las utilizamos para relacionarnos con la realidad a través de ellas, así como entre nosotros mismos. Vivimos entre las imágenes y no solo ellas entre nosotros.

A Surface-Enhanced Raman Scattering (SERS) spectrum of 4-cyanopyridine (4CNPy) was recorded on silver plasmonic nanoparticles and analyzed by using Density Functional Theory (DFT) calculations. Two simple molecular models of the metal−4CNPy surface complex with a single silver cation or with a neutral dimer (Ag+−4CNPy, Ag2−4CNPy), linked through the two possible interacting sites of 4CNPy (aromatic nitrogen, N, and nitrile group, CN), were considered. The calculated vibrational wavenumbers and intensities of the adsorbate and the isolated species are compared with the experimental Raman and SERS results. The analysis of the DFT predictions and the experimental data indicates that 4CNPy adsorbs preferentially on neutral/charged active sites of the silver nanoparticles through the nitrogen atom of the aromatic ring with a perpendicular orientation.

An electronic tongue has been developed to monitor the presence of ammonium nitrate in water. It is based on pulse voltammetry and consists of an array of eight working electrodes (Au; Pt; Rh; Ir; Cu; Co; Ag and Ni) encapsulated in a stainless steel cylinder. In a first step the electrochemical response of the different electrodes was studied in the presence of ammonium nitrate in water in order to further design the wave form used in the voltammetric tongue. The response of the electronic tongue was then tested in the presence of a set of 15 common inorganic salts; i.e.; NH4NO3; MgSO4; NH4Cl; NaCl; Na2CO3; (NH4)2SO4; MgCl2; Na3PO4; K2SO4; K2CO3; CaCl2; NaH2PO4; KCl; NaNO3; K2HPO4. A PCA plot showed a fairly good discrimination between ammonium nitrate and the remaining salts studied. In addition Fuzzy Art map analyses determined that the best classification was obtained using the Pt; Co; Cu and Ni electrodes. Moreover; PLS regression allowed the creation of a model to correlate the voltammetric response of the electrodes with concentrations of ammonium nitrate in the presence of potential interferents such as ammonium chloride and sodium nitrate.

A new electronic tongue to monitor the presence of glyphosate (a non-selective systemic herbicide) has been developed. It is based on pulse voltammetry and consists in an array of three working electrodes (Pt, Co and Cu) encapsulated on a methacrylate cylinder. The electrochemical response of the sensing array was characteristic of the presence of glyphosate in buffered water (phosphate buffer 0.1 mol·dm−3, pH 6.7). Rotating disc electrode (RDE) studies were carried out with Pt, Co and Cu electrodes in water at room temperature and at pH 6.7 using 0.1 mol·dm−3 of phosphate as a buffer. In the presence of glyphosate, the corrosion current of the Cu and Co electrodes increased significantly, probably due to the formation of Cu2+ or Co2+ complexes. The pulse array waveform for the voltammetric tongue was designed by taking into account some of the redox processes observed in the electrochemical studies. The PCA statistical analysis required four dimensions to explain 95% of variance. Moreover, a two-dimensional representation of the two principal components differentiated the water mixtures containing glyphosate. Furthermore, the PLS statistical analyses allowed the creation of a model to correlate the electrochemical response of the electrodes with glyphosate concentrations, even in the presence of potential interferents such as humic acids and Ca2+. The system offers a PLS prediction model for glyphosate detection with values of 098, −2.3 × 10−5 and 0.94 for the slope, the intercept and the regression coefficient, respectively, which is in agreement with the good fit between the predicted and measured concentrations. The results suggest the feasibility of this system to help develop electronic tongues for glyphosate detection.

Common sense, the thinking of the people par excellence, asserts that: a picture is worth a thousand words. This is a big mistake. The images are not carriers of meanings. The images always go through three basic processes are: production, circulation and reception. These processes are always determined in the time and social space. They are always the result of multiple relationships (social, ideological, political, moral, religious, etc.), established with them. Always there are so many elements beyond the image, which determines its meaning. The meaning of an image always depends on the relationships established with it in a historical time and space, socially and culturally determined. The images are never alone. To decrypt their meanings, you must first know the symbolic life of the societies in which they appear. Images do not have a single meaning because it depends on the historical and cultural geography which presents. The images always have a close relationship with the society they were born. The Muhammad cartoons not offend everyone equally.El sentido común, que es el pensamiento de las colectividades por excelencia, afirma que: una imagen dice más que mil palabras. Lo cual es un grave error. Las imágenes no son portadoras de significados. Las imágenes siempre atraviesan por tres procesos básicos que son: su producción, su circulación y su recepción. Estos procesos siempre están determinados en el tiempo y en el espacio sociales. Su significado siempre es el resultado de múltiples relaciones (sociales, ideológicas, políticas, morales, religiosas, etc.), que se establecen con las mismas. Es decir, siempre existen elementos que están más allá de la imagen, que determinan su significado. La manera en cómo se significa una imagen, siempre depende de las relaciones que se establecen con ella en un tiempo histórico y en un espacio, social y culturalmente determinado. Las imágenes nunca están solas. Para descifrar o conocer sus significados, primero es preciso conocer la vida simbólica de las sociedades donde aparecen. Las imágenes no tienen un solo significado puesto que éste depende de la geografía histórica y cultural donde se presentan. Las imágenes siempre guardan una estrecha relación con la sociedad que les vio nacer. Las caricaturas de Mahoma no ofenden a todos por igual.

The use of a voltammetric electronic tongue for the quantitative analysis of quality parameters in spring water is proposed here. The electronic voltammetric tongue consisted of a set of four noble electrodes (iridium, rhodium, platinum, and gold) housed inside a stainless steel cylinder. These noble metals have a high durability and are not demanding for maintenance, features required for the development of future automated equipment. A pulse voltammetry study was conducted in 83 spring water samples to determine concentrations of nitrate (range: 6.9–115 mg/L), sulfate (32–472 mg/L), fluoride (0.08–0.26 mg/L), chloride (17–190 mg/L), and sodium (11–94 mg/L) as well as pH (7.3–7.8). These parameters were also determined by routine analytical methods in spring water samples. A partial least squares (PLS) analysis was run to obtain a model to predict these parameter. Orthogonal signal correction (OSC) was applied in the preprocessing step. Calibration (67%) and validation (33%) sets were selected randomly. The electronic tongue showed good predictive power to determine the concentrations of nitrate, sulfate, chloride, and sodium as well as pH and displayed a lower R2 and slope in the validation set for fluoride. Nitrate and fluoride concentrations were estimated with errors lower than 15%, whereas chloride, sulfate, and sodium concentrations as well as pH were estimated with errors below 10%.

En este artículo -que discute la unidad y la diversidad en la antropología- se toma como pretexto la cultura para desarrollar un conjunto de reflexiones divididas en dos partes. En la primera se aborda el problema de la contraposición entre las perspectivas iluminista y romántica, con relación a la unidad y la diversidad. En la segunda se aborda el problema del concepto de cultura, sin olvidar la discusión del primer apartado. A lo largo del trabajo se argumenta que es difícil sostener la existencia de principios universales para comprender y pensar la cultura.

En este artículo se presentan los resultados de un estudio experimental de caracterización de concretos reforzados con fibras de acero y polipropileno para ser utilizados en pisos industriales, evaluando  parámetros como resistencia a compresión, módulo de elasticidad, tenacidad a compresión, resistencia a flexión, tenacidad a flexión, resistencia residual a flexión y energía de fractura. El programa de ensayos de caracterización consistió en la elaboración de probetas cilíndricas y prismáticas de concreto reforzado con fibras incluyendo nueve tipos de fibras: cinco de acero y cuatro sintéticas o de polipropileno. Así mismo se fabricaron probetas de concreto sin ningún tipo de refuerzo como parámetro de referencia, tomando como base un concreto utilizado para pisos industriales de 40 MPa de resistencia a flexión. De los resultados se observó que la forma y longitud de las fibras tienen influencia en el desarrollo de resistencia a flexión y otras propiedades mecánicas como la ductilidad, ya que la fibra de acero con extremos con ganchos mostró una mejor adherencia con el concreto, mientras que la fibra de copolímero tipo recta y polímeros tipo ondulada generaron un mejor desempeño en el concreto. Finalmente se observó una concordancia entre los valores obtenidos de tenacidad a compresión y a flexión.    Â

An electronic tongue for the qualitative analysis of aqueous solutions of salts hasbeen developed. The following set of electrodes was used: RuO2, Ag, and Cu in thick-filmtechnology and Au, Pb, Zn and Ni as small bars of the corresponding metal. The response ofthe designed “electronic tongue†was tested on a family of samples containing pure salt andcomplex mixtures. The electrodes were used as potentiometric un-specific sensors and thee.m.f. of each electrode in contact with a certain aqueous solution was used as input signalfor a PCA analysis. The study showed that the set of electrodes were capable to discriminatebetween aqueous solutions of salts basically by their different content in anions and cations(the anions SO42-, Cl-, PO4H2-, CO3H-, NO3- and cations Na+ and K+ were studied). In orderto better analyze the basis for the discrimination power shown by the electronic tongue, aquantitative analysis was also envisaged. A fair estimation of the concentrations of thedifferent ions in the solutions studied appeared to be possible using this electronic tonguedesign.Keywords:

The ionophore 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane(L1) was used for the development of miniaturised perchlorate-selective electrodes in thick-film technology. Different PVC membranes containing L1 and the plasticizers o-nitrophenyloctyl ether (NPOE), dibutyl phthalate (DBP), bis(2-ethylhexyl)sebacate (DOS) and dibutylsebacate (DBS) were prepared and placed on a graphite working electrode manufactured byusing thick film serigraphic technology. The perchlorate selective electrode containing DBSas plasticizer showed a potentiometric Nernstian response of -57 mV per decade in a rangeof perchlorate concentration from 1 x 10-4 to 1 x 10-1 M with a detection limit of 5 x 10-5 M.The ion selective electrodes containing DBP and NPOE as plasticizers exhibit a workingrange from 6.3 x 10-5 to 1 x 10-1 M and 7.4 x 10-5 to 1 x 10-1 M for perchlorate, respectively,with a detection limit of ca. 2.2 x 10-5 M. For all three electrodes a response time of ca. 5 s was found. The prepared electrodes do not show appreciable decay of the slope for at least 25 days. Potentiometric selectivity coefficients (log KpotClO4-,X-) with respect to the primaryanion perchlorate were evaluated using the fixed interference method. These coefficients areof the order of 10-1.7 or smaller, indicating the relatively poor interference of the differentanions studied.

El sentido común, que es el pensamiento de las colectividades por excelencia, afirma que: una imagen dice más que mil palabras. Lo cual es un grave error. Las imágenes no son portadoras de significados. Las imágenes siempre atraviesan por tres procesos básicos que son: su producción, su circulación y su recepción. Estos procesos siempre están determinados en el tiempo y en el espacio sociales. Su significado siempre es el resultado de múltiples relaciones (sociales, ideológicas, políticas, morales, religiosas, etc.), que se establecen con las mismas. Es decir, siempre existen elementos que están más allá de la imagen, que determinan su significado. La manera en cómo se significa una imagen, siempre depende de las relaciones que se establecen con ella en un tiempo histórico y en un espacio, social y culturalmente determinado. Las imágenes nunca están solas. Para descifrar o conocer sus significados, primero es preciso conocer la vida simbólica de las sociedades donde aparecen. Las imágenes no tienen un solo significado puesto que éste depende de la geografía histórica y cultural donde se presentan. Las imágenes siempre guardan una estrecha relación con la sociedad que les vio nacer. Las caricaturas de Mahoma no ofenden a todos por igual.

A inicios del 2007, un llamativo suceso se convirtió en el ‘foco de atención' de la opinión pública: 600 internas de La Villa de las niñas de Chalco, presentaron síntomas como: mareo, náuseas, vómitos y problemas musculares. Una vez descartados los factores orgánicos y con el aval de la ‘ciencia médica' se procedió a construir una versión oficial respaldada por la ‘ciencia' y los ‘sistemas de expertos'. En las entrevistas televisivas aparecían ‘académicos' de distintas instituciones del país opinando al respecto y lo sorprendente es que su ‘punto de vista' sobre el caso, resultaba ser tan inverosímil como el de las instancias de salud. Incluso, como se verá, las ‘versiones académicas' terminaron otorgándole, quizá sin quererlo, verosimilitud a la ‘versión oficial' de la Secretaría de Salud. Lo interesante del caso es que las explicaciones que se produjeron para justificar la existencia de los ‘hechos' se apegaron con estricto fervor romántico a las suposiciones hipnótico-epidemiológicas desarrolladas por la ‘psicología de masas' de finales del siglo XIX y principios del XX. Sirva el presente ensayo para hacer una revisión no sólo del curioso caso de la villa de las niñas sino de la forma en que la construcción de versiones, descripciones y explicaciones, circulan de modos particulares y que el entendimiento de la forma en cómo circulan dichas versiones, descripciones y explicaciones, permite entender la complejidad cultural de cualquier entorno social.

En este ensayo, hay tres puntos acerca de los cuales la discusión está estructurada. El primero, la soberbia interpretativa, analiza un problema central en la psicología social relacionada con la forma en que “persona” (como término, como concepto, como noción, etc.), es usado en la disciplina. Generalmente las personas son concebidas como “idiotas culturales” y no hay razones de peso para hacerlo así. El segundo, la incultura en la psicología aborda otro problema, pero relacionado con el anterior. En este apartado la discusión está orientada a reconocer que en las diferentes formas de ‘construir conocimiento’ en psicología social, la cultura como referencia, como variable, como un elemento importante de análisis no existe. El tercero, la ausencia de espíritu fenomenológico, tal como los otros dos apartados, es crítico con la psicología social, pero en este apartado la discusión enfatiza en la relevancia de la fenomenología para construir conocimiento de otra forma.