Sedimentology and depositional architecture of tufas deposited in stepped fluvial systems of changing slope: Lessons from the quaternary añamaza valley (Iberian Range, Spain)

The Pleistocene and Holocene tufas of the Añamaza valley (stepped build-ups, up to 70 m thick, along the valley) consist of several depositional stages separated by erosional surfaces. Eight associations of tufa and related carbonate facies, plus minor polygenic detrital facies, represent the processes that occurred in different fluvial and related environments. The bedrock lithology and structure controlled the location of the knickpoints along the valley and allowed separation of two stepped stretches with distinct conceptual facies models. The moderate-slope model includes extensive standing-water areas dammed by barrage-cascades. In the lakes, bioclastic silts, sands and limestones along with phytoclastic and marly, at places peaty, sediments formed. Abundant stem phytoherms account for extensive palustrine areas. The high-slope model consists of smaller dammed areas between close-up cascades and barrage-cascades, which were composed primarily of moss phytoherms and phytoclastic tufas. An outstanding feature is the extensive steep reach with phytoclastic and polygenic detrital sediments, and stepped cascades consisting of stromatolitic and moss phytoherms. There, the steep slope limited the preservation of stem phytoherms and favoured erosion. The geometry and thickness of the sedimentary fill (wedge-shaped units composed of cascade and barrage-cascade deposits downstream, and dammed and gentle-sloped channel deposits upstream) are therefore different for each model. Multi-storey wedges are a distinctive feature of the high-slope model. The initial knickpoint geometry and the tufa aggradation/progradation ratio on such steep surfaces (for example, related to changes in discharge) controlled the growth style of the cascades or barrage-cascades and, hence, the extent, thickness and vertical evolution of the upstream deposits. The sedimentological attributes and stable-isotope composition of the carbonate facies suggest a higher and more variable precipitation/evaporation ratio during the Pleistocene than during the Holocene, consistent with an overall decrease in the river discharge. This evolution was coupled with warm conditions, which prevailed during the stages of tufa formation. These results may help to assess architectural patterns in interpreting other basins, and underscore the significance of tufas as records of past hydrology and climate

Tufa sedimentation in changing hydrological conditions: the River Mesa (Spain)

The processes controlling tufa deposition along the River Mesa (NE Spain) were studied from April 2003 to September 2009, based on six-monthly monitoring of physical and chemical parameters of the river water and sedimentological characteristics, including deposition rates on tablets. With a mean annual discharge around 1.5m3/s, the sedimentation rate (mean 2mm/yr) recorded important spatial, seasonal and interannual variations. The river waters are of the calcium bicarbonate type. In this study, three distinct river stretches were distinguished based on the steady groundwater inputs, some of low-thermal nature. Groundwater discharges controlled the water chemical composition, and some sedimentation features too. At each stretch, an increase in pCO2 and conductivity was measured around the spring sites. Decreasing trends in conductivity or alkalinity with high enough saturation values with respect to calcite were only clearly observed in the intermediate stretch, which had higher tufa deposition rates than the other two. Tufa deposition rates were higher in cool (autumn+winter) than in warm (spring+summer) periods. In some low-rainfall warm periods, tufa deposition was inhibited or limited due to the low flow –mainly from groundwater inputs– and to the dryness of some river sites, which indeed favoured erosion during flooding. A decrease in yearly deposition rates from April 2006 onwards paralleled an important reduction in the river discharge. Groundwater inputs, drought periods and flood events should therefore be considered to understand fluvial tufa sedimentation in semi-arid conditions

Tufa sedimentation in changing hydrological conditions: the River Mesa (Spain)

The processes controlling tufa deposition along the River Mesa (NE Spain) were studied from April 2003 to September 2009, based on six-monthly monitoring of physical and chemical parameters of the river water and sedimentological characteristics, including deposition rates on tablets. With a mean annual discharge around 1.5m3 /s, the sedimentation rate (mean 2mm/yr) recorded important spatial, seasonal and interannual variations. The river waters are of the calcium bicarbonate type. In this study, three distinct river stretches were distinguished based on the steady groundwater inputs, some of low-thermal nature. Groundwater discharges controlled the water chemical composition, and some sedimentation features too. At each stretch, an increase in pCO2 and conductivity was measured around the spring sites. Decreasing trends in conductivity or alkalinity with high enough saturation values with respect to calcite were only clearly observed in the intermediate stretch, which had higher tufa deposition rates than the other two. Tufa deposition rates were higher in cool (autumn+winter) than in warm (spring+summer) periods. In some low-rainfall warm periods, tufa deposition was inhibited or limited due to the low flow –mainly from groundwater inputs– and to the dryness of some river sites, which indeed favoured erosion during flooding. A decrease in yearly deposition rates from April 2006 onwards paralleled an important reduction in the river discharge. Groundwater inputs, drought periods and flood events should therefore be considered to understand fluvial tufa sedimentation in semi-arid conditions

Intrinsic and extrinsic controls of spatial and temporal variations in modern fluvial tufa sedimentation: A thirteen-year record from a semi-arid environment

Sedimentological and hydrochemical parameters of the River Piedra (north-east Spain) were monitored every six months (from 1999 to 2012) at 24 sites, at which tablets were installed all along the river. The river water is of HCO3–SO4–Ca type and is notably influenced by inputs from upstream karstic springs. Tufa deposition was first detected 8 km downstream of these springs and greatly increased from there, primarily along the steeper stretch (i.e. within the Monasterio de Piedra Natural Park); then, deposition decreased through the most downstream stretch, with smaller ground water inputs. The spatial evolution of the tufa thickness, with parallel variations of PWP (Plummer, Wigley, Parkhurst) rates, was thus determined by the river water pCO2 which was controlled by ground water inputs and by the river bed slope. Five fluvial subenvironments and seven sedimentary facies were characterized. The water flow conditions are the primary factor responsible for the distinct deposition rates of facies, mainly through CO2-outgassing. Stromatolites and moss-tufa and alga-tufa had the highest rates, whereas loose tufa formed in slow-flowing water and tufa of spray areas had thinner deposition. A six-month pattern in the deposition rate was detected through thickness measurements. That pattern was parallel to the seasonal PWP rates. The increased deposition during warm periods (spring and summer; mean: 5·08 mm) compared with cool periods (autumn and winter; mean: 2·77 mm) is linked chiefly to temperature, which controlled the seasonal changes in the physico-chemical and biological processes; this finding is supported by a principal components analysis. Seasonal variations of insolation and day duration also contributed to such a deposition pattern. Large discharge events, which provoked erosion of tufa deposits and dilution of water, caused the reversal of the seasonal deposition rate pattern. Stromatolites are likely to preserve the most complete sedimentary record. Although tufas are a potentially sensitive record of climate-related parameters, erosion is an intrinsic process that may overwhelm the effects of such parameters. This issue should be considered in palaeoclimatic studies based on the tufa record, particularly in semi-arid conditions

Benthic diatoms on fluvial tufas of the Mesa River, Iberian Range, Spain

Background. The Mesa River (MR) in the Iberian Range (Spain) displays prominent, Pleistocene to present-day fluvial tufa deposits. Little of their associated microbiota has been studied to date despite the regional and historical relevance of these calcareous buildups. Goals. This paper is a preliminary exploration of the diatom (Bacillariophyta) genera associated with actively-growing tufa from 10 benthic environments along 24 km of the Mesa River. Methods. Bright- field microscopy, as well as consultation with specialists and specialized literature was used for taxonomic classification of diatoms. Results. We identified 25 diatom genera in three different types of sedimentary facies (porous and moss-algae rich, dense-laminated, and tufa-free gravel). Most diatoms were raphid pennate (class Bacillariophyceae), while few were centric (class Coscinodiscophyceae) or araphid pennate (class Fragilariophyceae). They appeared as integral components of the tufa structure along with cyanobacteria and other algae and mosses. Conclusions. Together with previous studies on the hydrochemistry and sedimentology of the MR, our interpretations suggest that HCO3-, pCO2, Ca2+, and TDIC negatively affect diatom richness and that their abundance is positively related to the presence of mosses and algae

Validity of student satisfaction surveys to assess teaching quality: the UPCT case study (Cartagena, Spain)

[ES] El programa DOCENTIA de ANECA se de­sarrolló como base para los modelos me­diante los cuales las universidades espa­ñolas evalúan la docencia del profesorado, una necesidad ligada a los requerimientos de transparencia y de mejora continua que están en la esencia del EEES. Entre los in­dicadores habituales en estos modelos destacan las encuestas de satisfacción de los estudiantes, cuya validez es objeto de debate desde el origen de su utilización. Una de las opiniones críticas más extendi­das sostiene que las encuestas no son una buena referencia, porque contienen ses­gos inasumibles. Con el objetivo de com­probar si existen realmente esos sesgos, se ha realizado un estudio estadístico a partir de los datos de indicadores de calidad en la Universidad Politécnica de Cartagena. Se ha empleado la regresión lineal múlti­ple, mediante el procedimiento conocido como regresión hacia atrás, para identifi­car las variables que pudieran influir en las valoraciones que hacen los estudiantes y cuantificar su efecto. El principal resultado del estudio es que las variables analizadas, que suelen citarse como causas de sesgo, muestran una influencia poco o nada signi­ficativa sobre los resultados de las encues­tas. Por otra parte, es importante subrayar que hay aspectos de la actividad docente que solamente pueden evaluarse a partir de la observación sistemática que hacen los estudiantes. Por todo ello considera­mos que las encuestas de satisfacción son un indicador indispensable, y es funda­mental que el peso que se les asigna en el modelo de evaluación docente refleje su importancia.[EN]  ANECA´s DOCENTIA program was developed to support the evaluation of teaching by the Spanish universities. Nowadays, teaching quality evaluation is a need linked to the transparency and continuous improvement requirements inherent to the European Higher Education Area. The indicators on the quality models frequently include student evaluation of teaching (SET), whose validity is the subject of a broad debate from the beginning of its use. One of the most widespread critical opinions argues that student surveys are not a good reference, as they contain non-assumable biases. With the aim of verify whether these biases actually exist, a statistical study has been carried out based on quality indicators data from the Technical University of Cartagena. Multiple linear regression has been used, through backward stepwise regression, to identify variables that may influence students’ opinions and to quantify their effects. The main result is that the variables analyzed, many of which are often cited as causes of bias, show little or no significant influence on student satisfaction with teaching. It is also important to remark that there are aspects of the teaching activity that can only be evaluated from the systematic observation made by students. Therefore, we believe that student surveys are an essential indicator, and their weight within teaching evaluation models should reflect their relevance.García Martín, A.; Montero Cases, T.; García León, J.; Vázquez Arenas, G. (2020). Validez de las encuestas de satisfacción de los estudiantes para evaluar la calidad docente: el caso de la UPCT (Cartagena). REDU. Revista de Docencia Universitaria. 18(1):275-290. https://doi.org/10.4995/redu.2020.12996OJS275290181Abadía, A.R., Bueno, C., Ubieto-Artur, M.I., Márquez, M.D., Sabaté, S., Jorba, H., Pagès, T. (2015). Competencias del buen docente universitario. Opinión de los estudiantes. REDU, Revista de Docencia Universitaria, 13(2), 363-390. https://doi.org/10.4995/redu.2015.5453Benton, S.L., Cashin, W.E. (2013). Student ratings of instruction in college and university courses. En M.B. Paulsen (ed.), Higher Education: Handbook of Theory and Research (pp. 279-326). https://doi.org/10.1007/978-94-017-8005-6_7Berk, R.A. (2014). Should student outcomes be used to evaluate teaching? Journal of Faculty Development, 28(2), 87-96. Recuperado de https://pdfs.semanticscholar. org/72dc/eb08a40f9019c72d5f20971bd3413fe06efd.pdfBoring, A. (2017). Gender biases in student evaluations of teaching. Journal of Public Economics, 145, 27-41. https://doi.org/10.1016/j.jpubeco.2016.11.006Casero, A. (2010). Factores moduladores de la percepción de la calidad docente. RELIEVE, Revista Electrónica de Investigación y Evaluación Educativa, 16(2), 1-17. https://doi.org/10.7203/relieve.16.2.4135Centra, J.A. (2003). Will teachers receive higher student evaluations by giving higher grades and less course work? Research in Higher Education, 44(5), 495-518. https://doi.org/10.1023/A:1025492407752Cohen, P.A. (1983). Comment on a selective review of the validity of student ratings of teaching. The Journal of Higher Education, 54(4), 448-458. https://doi.org/10.2307/1981907Elizondo, A., Novo, A., Silvestre, M. (2010). Igualdad de mujeres y hombres en las universidades españolas. Instituto de la Mujer, Madrid. Recuperado de http://www.inmujer.gob.es/areasTematicas/estudios/serieEstudios/docs/ igualdadUniversidades.pdfEmery, C.R., Kramer, T.R., Tian, R.G. (2003). Return to academic standards: a critique of student evaluations of teaching effectiveness. Quality Assurance in Education, 11(1), 37-46. https://doi.org/10.1108/09684880310462074Fernández Rico, J.E., Fernández, S., Álvarez, A., Martínez Camblor, P. (2007). Éxito académico y satisfacción de estudiantes con la enseñanza universitaria. RELIEVE, Revista Electrónica de Investigación y Evaluación Educativa, 13(2). https://doi.org/10.7203/relieve.13.2.4207Franklin, M. (2016). Student evaluations of teaching in business and accounting courses: a perspective and a suggested improvement. Cogent Business & Management, 3(1), 1-17. https://doi.org/10.1080/23311975.2016.1226458García Martín, A., García-León, J. (2017). Una experiencia de medición de la carga de trabajo percibida por los estudiantes para facilitar la coordinación horizontal. REDU, Revista de Docencia Universitaria, 15(1), 81-104. https://doi.org/10.4995/redu.2017.5987Greenwald, A.G., Gillmore, G.M. (1997). No pain, no gain? The importance of measuring course workload in student ratings of instruction. Journal of Educational Psychology, 89(4), 743-751. https://doi.org/10.1037/0022-0663.89.4.743Hammonds, F., Mariano, G.J., Ammons, G., Chambers, S. (2016). Student evaluations of teaching: improving teaching quality in higher education. Perspectives: Policy and Practice in Higher Education, 21(1), 26-33. https://doi.org/10.1080/13603108.2016.1227388Isla-Díaz, R., Marrero-Hernández, H., Hess-Medler, S., Soriano, M., Acosta-Rodríguez, S., Pérez-Monteverde, M.V., Blanco-Freijo, M. (2018). Una mirada longitudinal: ¿Es el "Docentia" útil para la evaluación del profesorado universitario? RELIEVE, Revista Electrónica de Investigación y Evaluación Educativa, 24(2). https://doi.org/10.7203/relieve.24.2.12142Jones, J. (1989). Students' ratings of teacher personality and teaching competence. Higher Education, 18(5), 551-558. https://doi.org/10.1007/BF00138747López-Aguado, M. (2018). La evaluación de la calidad de títulos universitarios. Dificultades percibidas por los responsables de los sistemas de garantía de calidad. Educación XX1, 21(1), 263-284. https://doi.org/10.5944/educxx1.20195Marsh, H., Roche, L. (1997). Making students' evaluations of teaching effectiveness effective. American Psychologist, 52(11), 1187-1197. https://doi.org/10.1037/0003-066X.52.11.1187Marsh, H. (2007). Students' evaluations of university teaching: dimensionality, reliability, validity, potential biases and usefulness. En R.P. Perry and J.C. Smart (eds.), The Scholarship of Teaching and Learning in Higher Education: An Evidence-Based Perspective, 319-383. Springer. https://doi.org/10.1007/1-4020-5742-3_9Mas Torelló, O. (2012). Las competencias del docente universitario: la percepción del alumno, de los expertos y del propio protagonista. REDU - Revista de Docencia Universitaria, 10(2), 299-318. https://doi.org/10.4995/redu.2012.6109Murray, H.G. (2005). Student evaluation of teaching: has it made a difference? Paper presented at the Annual Meeting of the Society for Teaching and Learning in Higher Education, Charlottetown, Prince Edward Island. Recuperado de https://www.stlhe.ca/wp-content/uploads/2011/07/Student-Evaluation-of- Teaching1.pdfRamírez, M.I., Montoya, J. (2014). La evaluación de la calidad de la docencia en la universidad: Una revisión de la literatura. REDU, Revista de Docencia Universitaria, 12 (2), 77-95. https://doi.org/10.4995/redu.2014.5641Sánchez, F., Rubio, R., Alonso, E., Retamal, K. (2009). La valoración de la actividad docente. Algo más que la opinión de los estudiantes. Boletín de Psicología, 97, 71-92. Recuperado de https://www.uv.es/seoane/boletin/previos/N97-5.pdfSpooren, P., Mortelmans, D., Thijssen, P. (2012). 'Content' versus 'style': acquiescence in student evaluation of teaching? British Educational Research Journal, 38(1), 3-21. https://doi.org/10.1080/01411926.2010.523453Uttl, B., White, C.A., Gonzalez, D. (2017). Meta-analysis of faculty's teaching effectiveness: Student evaluation of teaching ratings and student learning are not related. Studies in Educational Evaluation 54, 22-42. https://doi.org/10.1016/j.stueduc.2016.08.007Wolbring, T., y Treischl, E. (2016). Selection bias in students' evaluation of teaching. Causes of student absenteeism and its consequences for course ratings and rankings. Research in Higher Education, 57, 51-71. https://doi.org/10.1007/s11162-015-9378-

El prestigio cultural de la mímesis ritual

In general, mimesis can be ritual, visual or cognitive. The oldest mimesis takes place within the framework of rites, but in times of symbolic impoverishment many of them have lost their former vigour and have sometimes been reduced to mere folklore. Plato addressed visual mimesis, who said that it did not allow us to know reality with the depth or perfection with which it was possible to do it through rite or reflection. Aristotle delved into cognitive mimesis, pointing out that from it could be known the laws of nature, its ends and the way in which it operates to achieve them. By analysing these types of mimesis, we will highlight that a legitimate and effective way to reconnect man with the world and with reality is the enhancement of the rite.En general, la mímesis puede ser de orden ritual, visual o cognitiva. La mímesis más antigua tiene lugar en el marco de los ritos, pero en tiempos de empobrecimiento simbólico, muchos de ellos han perdido su antiguo vigor y, a veces, han quedado reducidos a mero folclore. La mímesis visual fue abordada por Platón de la que afirmó que no permitía conocer la realidad con la profundidad ni con la perfección con que era posible hacerlo mediante el rito o la reflexión. Aristóteles profundizó en una mímesis de índole cognitiva, señalando que a partir de ella podían conocerse las leyes de la naturaleza, sus fines y el modo en que opera para conseguirlos. Al analizar estos tipos de mímesis trataremos de poner de relieve que una forma legítima y eficaz de reconectar al hombre con el mundo y con la realidad es la puesta en valor del rito

Steady-State Dynamics of the Forest Fire Model on Complex Networks

Many sociological networks, as well as biological and technological ones, can be represented in terms of complex networks with a heterogeneous connectivity pattern. Dynamical processes taking place on top of them can be very much influenced by this topological fact. In this paper we consider a paradigmatic model of non-equilibrium dynamics, namely the forest fire model, whose relevance lies in its capacity to represent several epidemic processes in a general parametrization. We study the behavior of this model in complex networks by developing the corresponding heterogeneous mean-field theory and solving it in its steady state. We provide exact and approximate expressions for homogeneous networks and several instances of heterogeneous networks. A comparison of our analytical results with extensive numerical simulations allows to draw the region of the parameter space in which heterogeneous mean-field theory provides an accurate description of the dynamics, and enlights the limits of validity of the mean-field theory in situations where dynamical correlations become important.Comment: 13 pages, 9 figure

Critical phenomena in complex networks

The combination of the compactness of networks, featuring small diameters, and their complex architectures results in a variety of critical effects dramatically different from those in cooperative systems on lattices. In the last few years, researchers have made important steps toward understanding the qualitatively new critical phenomena in complex networks. We review the results, concepts, and methods of this rapidly developing field. Here we mostly consider two closely related classes of these critical phenomena, namely structural phase transitions in the network architectures and transitions in cooperative models on networks as substrates. We also discuss systems where a network and interacting agents on it influence each other. We overview a wide range of critical phenomena in equilibrium and growing networks including the birth of the giant connected component, percolation, k-core percolation, phenomena near epidemic thresholds, condensation transitions, critical phenomena in spin models placed on networks, synchronization, and self-organized criticality effects in interacting systems on networks. We also discuss strong finite size effects in these systems and highlight open problems and perspectives.Comment: Review article, 79 pages, 43 figures, 1 table, 508 references, extende

Effectiveness and safety of first-generation protease inhibitors in clinical practice: Hepatitis C virus patients with advanced fibrosis

AIM: To evaluates the effectiveness and safety of the first generation, NS3/4A protease inhibitors (PIs) in clinical practice against chronic C virus, especially in patients with advanced fibrosis. METHODS: Prospective study and non-experimental analysis of a multicentre cohort of 38 Spanish hospitals that includes patients with chronic hepatitis C genotype 1, treatment-nai¨ve (TN) or treatment-experienced (TE), who underwent triple therapy with the first generation NS3/4A protease inhibitors, boceprevir (BOC) and telaprevir (TVR), in combination with pegylated interferon and ribavirin. The patients were treatment in routine practice settings. Data on the study population and on adverse clinical and virologic effects were compiled during the treatment period and during follow up. RESULTS: One thousand and fifty seven patients were included, 405 (38%) were treated with BOC and 652 (62%) with TVR. Of this total, 30% (n = 319) were TN and the remaining were TE: 28% (n = 298) relapsers, 12% (n = 123) partial responders (PR), 25% (n = 260) null-responders (NR) and for 5% (n = 57) with prior response unknown. The rate of sustained virologic response (SVR) by intention-to-treatment (ITT) was greater in those treated with TVR (65%) than in those treated with BOC (52%) (P < 0.0001), whereas by modified intention-to-treatment (mITT) no were found significant differences. By degree of fibrosis, 56% of patients were F4 and the highest SVR rates were recorded in the non-F4 patients, both TN and TE. In the analysis by groups, the TN patients treated with TVR by ITT showed a higher SVR (P = 0.005). However, by mITT there were no significant differences between BOC and TVR. In the multivariate analysis by mITT, the significant SVR factors were relapsers, IL28B CC and non-F4; the type of treatment (BOC or TVR) was not significant. The lowest SVR values were presented by the F4-NR patients, treated with BOC (46%) or with TVR (45%). 28% of the patients interrupted the treatment, mainly by non-viral response (51%): this outcome was more frequent in the TE than in the TN patients (57% vs 40%, P = 0.01). With respect to severe haematological disorders, neutropaenia was more likely to affect the patients treated with BOC (33% vs 20%, P = 0.0001), and thrombocytopaenia and anaemia, the F4 patients (P = 0.000, P = 0.025, respectively). CONCLUSION: In a real clinical practice setting with a high proportion of patients with advanced fibrosis, effectiveness of first-generation PIs was high except for NR patients, with similar SVR rates being achieved by BOC and TVR