Universidad de Burgos
  • Burgos, Castilla y León, Spain
Recent publications
In this work, we design and analyze a discrete model to approximate the solutions of a parabolic partial differential equation in multiple dimensions. The mathematical model considers a nonlinear reaction term and a space-dependent diffusion coefficient. The system has a Gibbs' free energy, we establish rigorously that it is non-negative under suitable conditions, and that it is dissipated with respect to time. The discrete model proposed in this work has also a discrete form of the Gibbs' free energy. Using a fixed-point theorem, we prove the existence of solutions for the numerical model under suitable assumptions on the regularity of the component functions. We prove that the scheme preserves the positivity and the dissipation of the discrete Gibbs' free energy. We establish theoretically that the discrete model is a second-order consistent scheme. We prove the stability of the method along with its quadratic convergence. Some simulations illustrating the capability of the scheme to preserve the dissipation of Gibb's energy are presented.
The 2018/844 Energy Performance of Buildings Directive (EU) has widened the scope of appropriate design of buildings from a pure energy performance and carbon emissions perspective to a wider scope that includes indoor comfort, and indoor air quality among others. To this effect, external parameters, especially solar energy, have a strong impact on the energy performance of buildings in Mediterranean regions, which requires careful consideration when it comes to benefiting from natural lighting while avoiding solar overheating. This paper addresses the considerations of natural lighting in the deep renovation of a housing block in the Mediterranean climate of the Republic of Malta, comparing some of the usual illuminance ranges to achieve optimal conditions based on international recommendations. DesignBuilder v7.0.0.102 has been the selected software to model the building that has been calibrated through experimental measurements. The model enabled the natural lighting conditions in the building evaluated and the effectiveness of suggested improvements to be determined. Results pointed out that the building under study satisfies the international standards about the prevention of visual discomfort only. Increasing the size of windows in identified zones, especially the first floor, was found to help improve other natural lighting characteristics. One of the proposed designs (Model 6) that replaces single-glazed with double-glazed windows that include an external spectrally-selective coating would significantly improve access to natural light bringing the building closer to the recommended levels of Annual Sunlight Exposure and reducing artificial lighting usage by up to five times. The relocation of room spaces could also reduce the use of artificial lighting.
Spatial analysis has been much used to examine the distribution of archaeological remains at Pleistocene sites. However, little is known about the distribution patterns at sites identified as hunting camps, i.e., places occupied over multiple short periods for the capture of animals later transported to a base camp. The present work examines a Neanderthal hunting camp (the Navalmaíllo Rock Shelter in Pinilla del Valle, Madrid, Spain) to determine whether different activities were undertaken in different areas of the site. A spatial pattern was detected with a main cluster of materials (lithic tools, faunal remains, and coprolites) clearly related to the presence of nearby hearths—the backbone of the utilised space. This main cluster appears to have been related to collaborative and repetitive activities undertaken by the hunting parties that used the site. Spatial analysis also detected a small, isolated area perhaps related to carcasses processing at some point in time and another slightly altered by water.
Quality control in the food industry is of the upmost importance from the food safety, organoleptic and commercial viewpoints. Accordingly, the development of in situ, rapid, and costless analytical tools is a valuable task in which we are working. Regarding this point, the copper content of grape must has to be determined by wineries along the wine production process. For this purpose, grape must samples are sent to laboratories where the copper content is measured usually by flame atomic absorption spectrometry or by inductively coupled plasma mass spectrometry. We herein propose a straightforward, rapid, and inexpensive methodology based both on a film-shaped colorimetric polymer sensor and a smartphone method that at the same time can be used by unskilled personnel. The sensory polymer films change their color upon dipping them on the grape must, and the color evolution is analyzed using the digital color parameters of a picture taken to the film with a smartphone. Furthermore, the analytical procedure is automatically carried out by a smartphone app. The limit of detection of copper of the polymer sensor is 0.08 ppm. Following this approach, 18 production samples coming from the French Groupe ICV company were studied. The copper content of the samples was analyzed by the usual procedure carried out by the company (flame atomic absorption spectrometry) and by the method proposed in this work, ranging this content from 0.41 to 6.08 ppm. The statistical study showed that the results of both methods are fully consistent, showing the validity of the proposed method for the determination of copper in grape must within the frame of wine production wineries and industries.
Clientelism is a widespread and persistent practice in Latin America with significant ramifications for political actors and systems. This paper analyses its impact upon ideological overlapping, which is one of the aspects of ideological competition that has received disparate levels of attention depending on the region of study. The hypothesis examined is that clientelism reduces the ideological differentiation of political parties because, firstly, a clientelist environment makes it difficult for political actors to use left/right categories, thereby contributing to a reduction in parties’ ideological identities. Secondly, the use of clientelist practices by parties fosters ideological overlapping with other parties, given the lack of incentives for them to differentiate themselves ideologically from one another. To test this relationship, a multilevel regression analysis was performed of 86 Latin American parties since 2009.
The development of an electrochemical procedure for the determination of 4-ethylguaiacol and its application to wine analysis is described. Modified screen-printed carbon electrodes (SPCEs) with fullerene C60 (C60) have been shown to be efficient in this kind of analysis. The developed activated C60/SPCEs (AC60/SPCEs) were adequate for the determination of 4-ethylguaicol, showing a linear range from 200 to 1000 µg/L, a reproducibility of 7.6% and a capability of detection (CCβ) value of 200 µg/L, under optimized conditions. The selectivity of the AC60/SPCE sensors was evaluated in the presence of possibly interfering compounds, and their practical applicability was demonstrated in the analysis of different wine samples obtaining recoveries ranging from 96 to 106%. Graphical Abstract
Some of the Sima de los Huesos (SH) humeri have been previously studied and described elsewhere. Here we present an updated inventory and a review of the specimens recovered to the present day. The morphological key traits of the adult and subadult specimens are described, discussed, and illustrated. The SH humeri share with Neandertals many traits usually considered to be Neandertal specializations, thus, most of this morphological pattern is not exclusive to them. The variation found within fossil samples stresses the frequential nature of all these traits and in the specific case of the SH humeri, most of the traits considered as phylogenetically relevant are retained by their descendants, the Neandertals. Some traits are plesiomorphic for the entire genus Homo or are present in European hominins since the early Pleistocene. Finally, some other traits display high variability within the SH sample or different hominin samples and are of uncertain phylogenetic value. Altogether, this evidence is consistent with the hypothesis based on the overall cranial and postcranial morphology that the SH hominins are a sister group to the later Neandertals.
This work experimentally evaluates the friction shear behavior of Electric Arc Furnace (EAF) concrete, compared to its reference counterpart made with natural aggregates only. For this scope, two concrete mixes were casted, both containing a blended cement with 30% of fly ash to improve their sustainability. For each mix, other than analyzing the main mechanical properties (compressive, tensile strength and elastic modulus), push-off specimens were tested to obtain the shear strength, failure modes, stress-slip and stress-crack opening curves. The results obtained here clearly identify an enhancement of the shear strength τ of EAF concrete compared to the reference, even though the relation between τ and concrete tensile strength f ct is similar between the two concretes. Results are also compared with ones in literature, dealing with ordinary and recycled aggregate concrete (RAC). Further, existing models from both designing codes and literature were applied to the experimental results, obtaining conservative predictions in all cases. The safety margin for the EAF concrete was found to be higher than for the reference concrete.
Understanding consumers’ behavior and their handling of high-risk foods at home is essential for reducing the number of foodborne illnesses. This study shows the results of a cross-national analysis of consumers’ perception from nine countries, and the identification of customers’ clusters and its characteristics in order to understand customers’ behavior, and to build safe chilled ready-to-eat (RTE) foods prevention strategies. The cluster analysis resulted in two clusters: (1) “Precautious consumers” characterized by the orientation towards pre-packed RTE foods, with consumers mainly coming from Bosnia and Herzegovina, India, Poland, Portugal, Spain, and Turkey. Their attitudes and self-reported practices may be categorized as less risky in terms of food-borne illnesses connected with the consumption of RTE foods; (2) “Unconcerned consumers” preferred cutting and slicing RTE foods freshly at the point of purchase, usually sold at the delicatessen department in a supermarket or at open markets. Those consumers mostly came from Croatia, Serbia and Slovenia and their attitudes and self-reported practices were riskier. These results allow a better understating of what characterizes consumers of RTE foods in different countries.
The postcranial skeleton of fossil hominins is crucial for reconstructing the processes that occurred between the time of death and the recovery of the bones. Thousands of postcranial skeletal fragments from at least 29 hominin individuals have been recovered from the Sima de los Huesos Middle Pleistocene site in Spain. This study's primary objective is to address the main taphonomic features of the postcranial remains from the Sima de los Huesos sample, including antemortem, perimortem, and postmortem skeletal disturbances. We present an updated assessment of the bone surface modification analysis, the fracture pattern analysis, and the skeletal part representation to facilitate interpretation of the biostratinomic and fossil-diagenetic processes in this large paleoanthropological collection. We conclude that carnivores (probably bears) had limited access to the hominin bones and complete bodies were probably placed in the site.
The first waves of the COVID-19 pandemic were times of great change in the lives of university students and their families in Spain. The aim of this study was to explore the psychosocial aspects and preventive measures carried out during the COVID-19 pandemic by students and family members of the nursing degree students of the University of Valladolid (Spain). The number of people surveyed was 877, by means of an ad hoc questionnaire. Relationships between variables were established by means of the Chi-square test and Student’s t-test. In addition, multivariate logistic regression was generated. The significance level used was 0.05. Students and family members maintained preventive measures= such as hand washing, correct use of masks =in closed places, avoiding crowds and maintaining social distance, but at low rates (close to 20% in all cases). Regarding psychosocial aspects, 41.07% of the participants suffered from anxiety and loneliness, while 5.2% needed to take drugs to reduce anxiety or sleep and 66.07% were dependent on technology. Suicidal behavior is related to stress, anxiety, loneliness, poor family relationships, psychotropic drug use and technology abuse. The pandemic has caused life changes in university students and their families at the psychosocial level, generating high figures of suicidal ideation regardless of age. Preventive measures adopted to control the pandemic have not been followed for the most part.
Recently, several hydrogen-assisted failures have been reported on different nickel alloys used in the subsea oil and gas industries. It is thus essential to correlate hydrogen uptake and diffusion behavior with stress conditions for an in-depth understanding of the failures. This study reports the first-hand finding on hydrogen diffusion behavior in a nickel Alloy 625 under different pre-strain levels by combining the electrochemical permeation test and diffusion model, with a particular focus on the effect of grain boundary carbide. As the multiplication of dislocations was claimed to trap hydrogen atoms and reduce the diffusivity by increasing the strain levels from 0.05 to 0.2, an acceleration in hydrogen diffusivity was however observed when the strain was higher than 0.1. This phenomenon was deduced to be caused by the diffusion highways by the hydrogen-enhanced strain-induced vacancy formation at the grain boundaries and reduced hydrogen trapping by the fractured carbides.
In order to ensure casting simulation plausibility, as requested in wind certifications, its default mechanical property prediction is evaluated based on results tested from wind structural castings made in furan no-bake resin systems. Through a standard definition of pre-process parameters and the default post-process provided by commercial software, it is verified that predictions on nodular cast iron are already in order of magnitude with tests on wind castings. To improve the default mechanical property prediction, the specific process of each supplier, an advanced definition of pre-process parameters and new post-process criteria should be considered.
The application of edutainment and gamification resources as complementary methodologies allows to reinforce and facilitate the internalization of learning, although there are hardly any studies that relate its use to the organizational culture of educational establishments. This research aims to assess the effectiveness of the Foodball gamification program, applied to nutritional education as a strategy for innovation and learning and, specifically, its relationship with the teacher perception of organizational culture in education. A transversal methodology was used with students between 7 and 10 years old (n = 185), and teachers (n = 55) from 14 public primary schools in Rome and Ostia (Italy). Ad hoc assessment scales and the Organizational Culture Inventory (OCI) were used in the collection of information. For the analysis of the data, descriptive and inferential tests were carried out. The results associate the potential of these resources with an active participation and motivation in the learning process, as well as with the internalization of the information. Likewise, the teachers who participated in the educational entertainment crossmedia format obtained higher scores in the perception of the organizational culture , revealing significant differences according to gender and the acceptance of error as a unit value, and age with the perception of innovation. It is concluded in the need to deepen in these results through the design of longitudinal studies on the use of gamification resources and its effective incidence in the organizational culture.
After more than three decades of extensive investigations in supramolecular polymers, strategies for self‐limiting growth still remain challenging. Herein, we exploit a new V‐shaped monomer design to achieve anti‐cooperatively formed oligomers with superior robustness and high luminescence. In toluene, the monomer‐oligomer equilibrium is shifted to the monomer side, enabling the elucidation of the molecular packing modes and the resulting (weak) anticooperativity. Steric effects associated with an antiparallel staircase dye organization are proposed to outcompete aromatic and unconventional B‐F···H‐N/C interactions, restricting the growth at the stage of oligomers. In methylcyclohexane (MCH), the packing modes and the anticooperativity are preserved; however, pronounced solvophobic and chain enwrapping effects lead to thermally ultrastable oligomers. Our results shed light on understanding anticooperative effects and restricted growth in self‐assembly.
In this systematic review, a series of didactic proposals and experiences that have been developed over recent years in formal education are presented with the common purpose of ensuring that students with special educational needs learn science. Initially, only 54 publications on the topic were identified, which underlines the scarce research over the last 20 years and the small percentage of papers published in research journals and conference proceedings within this area. From among those publications, our review is focused on the 27 that report the implementation of didactic interventions: 11 at specific special education centres and 16 at regular educational centres. Explicit instruction was considered a fundamental strategy in the first group, while varied experiences and methods were among the most relevant approach in the second group. In addition, both educational environments involve learner-centred teaching approaches, with the implementation of inquiry-based and hands-on activities, in line with the general results of research in Science Education that does not specifically deal with SSEN. Ensuring that all learners have the opportunity to learn science requires more specific and complementary studies that consolidate the evidence of these results, taking into account the diversity of learners in classrooms for the benefit of all.
Sunflower seeds, one of the main oilseeds produced around the world, are widely used in the food industry. Mixtures of seed varieties can occur throughout the supply chain. Intermediaries and the food industry need to identify the varieties to produce high-quality products. Considering that high oleic oilseed varieties are similar, a computer-based system to classify varieties could be useful to the food industry. The objective of our study is to examine the capacity of deep learning (DL) algorithms to classify sunflower seeds. An image acquisition system, with controlled lighting and a Nikon camera in a fixed position, was constructed to take photos of 6000 seeds of six sunflower seed varieties. Images were used to create datasets for training, validation, and testing of the system. A CNN AlexNet model was implemented to perform variety classification, specifically classifying from two to six varieties. The classification model reached an accuracy value of 100% for two classes and 89.5% for the six classes. These values can be considered acceptable, because the varieties classified are very similar, and they can hardly be classified with the naked eye. This result proves that DL algorithms can be useful for classifying high oleic sunflower seeds.
Degenerative cervical myelopathy (DCM) consists of spinal cord damage due to its compression through the cervical spine. The leading cause is degenerative. The diagnosis is clinical, and the therapeutic approach is usually surgical. Confirmation of the diagnostic suspicion is done by magnetic resonance imaging (MRI); however, this test lacks functional information of the spinal cord, the abnormality of which may precede involvement in neuroimaging. Neurophysiological examination using somatosensory evoked potentials (SSEPs) and transcranial magnetic stimulation (TMS) allows for an evaluation of spinal cord function, and provides information in the diagnostic process. Its role in the post-surgical follow-up of patients undergoing decompressive surgery is being studied. We present a retrospective study of 24 patients with DCM and surgical decompression who underwent neurophysiological tests (TMS and SSEP) before, 6, and 12 months after surgery. The result of the TMS and the SSEP in the post-operative follow-up did not correlate with the clinical outcome, either subjective or measured by clinical scales at six months. We only found post-surgical improvement of central conduction times (CMCTs) in patients with severe pre-surgical motor impairment on TMS. In patients with normal pre-surgical CMCT, we found a transient worsening with return to baseline at the one-year follow-up. Most patients presented pre-surgical increased P40 latency at diagnosis. CMCT and SSEP were more related to clinical outcomes one year after the surgical procedure and were very useful in diagnosing.
The feasibility of industrial subcritical water treatment on Gelidium sesquipedale residue through scaling up from the lab to pilot system in discontinuous mode (geometric scale-up factor = 50), at 130 and 175 °C (5% biomass), was investigated. The maximum volumes of the reactors were 500 mL at the lab-scale and 5 L at the pilot-scale system. At 175 °C, faster extraction/hydrolysis was observed for the pilot plant, but maximum yields were similar: 71.4 and 78.6% for galactans, 9.8 and 10.4% for glucans, and 92.7 and 86.1% for arabinans in pilot scale and lab scale, respectively, while the yields for proteins accounted nearly 40%. The highest yields for amino acids were observed for the smallest ones, while lower yields were determined for polar amino acids. The total phenolic content and color intensity progressively increased along time at lab scale, while a plateau was reached at the pilot level. Lower extraction yields but reproducible results were obtained at 130 °C. Finally, the pilot scale was essayed at a higher biomass loading (15%), and successful results were obtained, supporting the feasibility of the scaling-up process.
The literature about the influence of country corruption on corporate cash holdings is not conclusive as there are studies supporting both a positive and negative relationship. To better explain this relationship, our study introduces a corporate-level mediating variable, i.e. the company's willingness to fight bribery as part of its CSR policy. Using a sample of 1,075 listed firms from 21 European Union countries for the period 2008–2019 (7,771 firm-year observations), we find a partial mediating effect of the corporate anti-bribery policy on the relationship between country corruption and corporate cash holdings. On the one hand, according to the shielding argument, country corruption negatively influences corporate cash holdings. And, on the other hand, there is a mediating effect such that firms in corrupt countries adopt less tough anti-bribery policies and, instead, they reduce their cash holdings both to protect themselves from expropriation and to signal their limit on bribe payments.
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1,995 members
José Manuel Galán
  • Ingeniería de Organización
Luis R. Izquierdo
  • Management Engineering
Juan Mielgo-Ayuso
  • Departamento de Ciencias de la Salud
Sagrario Beltrán
  • Department of Biotechnology and Food Science
Hospital del Rey, s/n, 09001, Burgos, Castilla y León, Spain
Head of institution
Manuel Perez-Mateos
947 25 87 36