Materials with a high electromagnetic activity usually present a strong resonant response that produces extreme values for the constitutive parameters, but in a narrow frequency range. Here, a chiral material composed by four helical-like resonators, as the unit cell, able to produce high rotatory dispersion as well as low circular dichroism in a wide frequency band is presented. The transmission and reflection coefficients of a thin slab of such material have been determined by using a free-wave experimental set up and numerical simulations. The experimental results show a cross-polarization conversion in transmission mode for linearly polarized incident waves in a 2 GHz bandwidth centered at 10 GHz and a polarization conversion ratio larger than 0.97.
Plant material culture can offer unique insights into the ways of life of prehistoric societies; however, its perishable nature has prevented a thorough understanding of its diverse and complex uses. Sites with exceptional preservation of organic materials provide a unique opportunity for further research. The burial site of Cueva de los Murciélagos in southern Iberia, uncovered during 19th-century mining activities, contained the best-preserved hunter-gatherer basketry in southern Europe, together with other unique organic artifacts associated with the first farming communities, such as sandals and a wooden hammer. We present 14 14 C dates for the perishable artifacts (N = 76), situating the assemblage between the Early and Middle Holocene (c. 7500 to 4200 cal BCE). Our integrated analysis includes raw material determination and technological and chrono-cultural contextualization of this unique and important set of materials.
The oxidative potential (OP) is defined as the ability of inhaled PM components to catalytically/non-catalytically generate reactive oxygen species (ROS) and deplete lung antioxidants. Although several studies have measured the OP of particulate matter (PM OP) soluble components using different antioxidants under neutral pH conditions, few studies have measured PM OP with acidic lung fluids. This study provides new insights into the use of acidic rather than neutral fluids in OP assays. Thus, the first aim of this study was to clarify the effect of using an acidic lung fluid on ascorbic acid (AA) depletion. This was achieved by measuring the oxidative potential (OP-AA) of individual compounds known to catalyze the AA oxidation (CuSO4, CuCl2, and 1,4-NQ) in artificial lysosomal fluid (ALF, pH 4.5), a commonly used acidic simulated lung fluid, and in a neutral fluid (phosphate-buffered saline (PBS1x), pH 7.4). Our results from these individual compounds showed a significant decrease of OP-AA in the acidic fluid (ALF) with respect to the neutral fluid (PBS). Then, the second aim of this work was to investigate whether the OP-AA assay could be applied to PM2.5 samples extracted in acidic conditions. For this purpose, OP-AA and bioaccessible concentrations of metal(loid)s (V, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb, and Pb) of PM2.5 samples collected in an urban-industrial area that were extracted in ALF were analyzed. The mean volume-normalized OP (OP-AAv) value was 0.10 ± 0.07 nmol min⁻¹ m⁻³, clearly lower than the values found in the literature at neutral pH. OP-AAv values were highly correlated with the ALF-bioaccessible concentration of most of the studied metal(loid)s, mainly with Cu and Fe.
Prehistoric and Archaeological research has pointed out the role of marine resources in modern humans’ cognitive and cultural developments. Maritime adaptations constitute a key component of the sociocultural evolution in Eastern Arabia. During the Neolithic (c. 6500–3300 BCE), it is expressed by the colonisation of offshore islands supported by advanced seafaring and the exploitation of marine resources not only for staple food but also for obtaining hard animal materials used for both symbolic and technological productions, respectively in the form of personal adornments and tooling. Although tools made of retouched large marine mollusc shells are reported on several sites, no detailed study has been conducted on their function and role within the socio-technological processes. The present study introduces a prospective approach for the functional analysis of archaeological shell tools from Eastern Arabia. A reference collection of use-wear traces made experimentally has been built: it compiles the results of 65 experiments (23 are documented and illustrated in the present study), including the processing of various animal, vegetal, and mineral materials. Use-wear traces have been observed and described using both low and high-power magnifications (conducted mainly at 100 ×). It provides helpful methodological support for future comparisons with archaeological specimens. The procurement conditions of the shell valves and the techniques of retouch have been discussed in detail, allowing further considerations on the degree of the socio-technological investment devoted to these peculiar artefacts.
Pancreas transplantation has more than 50 years of history, being performed in more than 200 centres around the world, most of them in the United States and Europe. While in the US fellowship programmes were developed in the 1970s that allowed training of many transplant surgeons, formal training in pancreas transplantation in Europe was limited. Since 2007, the UEMS (European Union of Medical Specialists) developed a Division of Transplantation, which is part of the UEMS Section of Surgery. This Division is responsible for the accreditation in transplantation surgery of European trainees via a formal examination process. The Division is also accrediting transplant centres that offer training in transplantation surgery.
It has been proposed that climate change and the arrival of modern humans in Europe affected the disappearance of Neanderthals due to their impact on trophic resources; however, it has remained challenging to quantify the effect of these factors. By using Bayesian age models to derive the chronology of the European Middle to Upper Paleolithic transition, followed by a dynamic vegetation model that provides the Net Primary Productivity, and a macroecological model to compute herbivore abundance, we show that in continental regions where the ecosystem productivity was low or unstable, Neanderthals disappeared before or just after the arrival of Homo sapiens . In contrast, regions with high and stable productivity witnessed a prolonged coexistence between both species. The temporal overlap between Neanderthals and H. sapiens is significantly correlated with the carrying capacity of small- and medium-sized herbivores. These results suggest that herbivore abundance released the trophic pressure of the secondary consumers guild, which affected the coexistence likelihood between both human species.
Complex signalling between the apical ectodermal ridge (AER - a thickening of the distal epithelium) and the mesoderm controls limb patterning along the proximo-distal axis (humerus to digits). However, the essential in vivo requirement for AER-Fgf signalling makes it difficult to understand the exact roles that it fulfils. To overcome this barrier, we developed an amenable ex vivo chick wing tissue explant system that faithfully replicates in vivo parameters. Using inhibition experiments and RNA-sequencing, we identify a transient role for Fgfs in triggering the distal patterning phase. Fgfs are then dispensable for the maintenance of an intrinsic mesodermal transcriptome, which controls proliferation/differentiation timing and the duration of patterning. We also uncover additional roles for Fgf signalling in maintaining AER-related gene expression and in suppressing myogenesis. We describe a simple logic for limb patterning duration, which is potentially applicable to other systems, including the main body axis.
Background Aortic valve stenosis (AVS) affects 25% of the population over 65 years. At present, there is no curative medical treatment for AVS and therefore the surgical approach, consisting of transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR), is the treatment of choice. Methodology The aim of this study was to analyze the sociodemographic and clinical characteristics, quality of life and functionality of a sample of patients with AVS over 75 years of age, who underwent TAVR or SAVR, applying standard clinical practice. A prospective multicenter observational study was conducted in two hospitals of the Spanish National Health System. Data were collected at baseline, 1, 6 months and 1 year. Results In total, 227 participants were included, with a mean age of 80.6 [SD 4.1]. Statistically significant differences were found in terms of quality of life, which was higher at 1 year in patients who underwent SAVR. In terms of functionality, SAVR patients obtained a better score ( p < 0.01). However, patients who underwent TAVR began with a worse baseline situation and managed to increase their quality of life and functionality after 1 year of follow-up. Conclusion The individualized choice of TAVR or SAVR in patients with AVS improves patients’ quality of life and function. Moreover, the TAVR procedure in patients with a worse baseline situation and a high surgical risk achieved a similar increase in quality of life and functionality compared to patients undergoing SAVR with a better baseline situation.
Background Chronic lymphocytic leukemia (CLL) etiology is poorly understood, and carcinogenic chemicals in drinking and recreational water are candidates. Objective To evaluate the association between drinking-water exposure to trihalomethanes (THMs) and nitrate as well as lifetime swimming pool attendance and CLL. Methods During 2010–2013, hospital-based CLL cases and population-based controls were recruited in Spain, providing information on residential histories, type of water consumed and swimming pool attendance. Average THMs and nitrate levels in drinking water were linked to lifetime water consumption. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models. Results Final samples for residential tap water analyses and swimming pool attendance analyses were 144 cases/1230 controls and 157 cases/1240 controls, respectively. Mean (SD) values for average lifetime residential brominated THMs and chloroform in tap water (μg/L), and ingested nitrate (mg/day) were 48.1 (35.6), 18.5 (6.7) and 13.7 (9.6) respectively in controls; and 72.9 (40.7), 17.9 (5.4), and 14.1 (8.8) in CLL cases. For each 10 μg/L increase of brominated THMs and chloroform lifetime-average levels, the ORs (95% CI) were 1.22 (1.14, 1.31) and 0.54 (0.34, 0.87), respectively. For each 5 mg/day increase of ingested nitrate, the OR of CLL was 0.91 (0.80, 1.04). The OR of lifetime pool users (vs. non-users) was 2.38 (1.61, 3.52). Upon performing annual frequency of attending pools analysis through categorization, the second and third categories showed an ORs of 2.36 (1.49, 3.72) and 2.40 (1.51, 3.83), respectively, and P-trend of 0.001. Impact statement This study identifies an association of long-term exposure to THMs in drinking water, at concentrations below the regulatory thresholds and WHO guidelines, and swimming pool attendance, with chronic lymphocytic leukemia (CLL). These unprecedented findings are highly relevant since CLL is an incurable cancer with still unknown etiology and because the widespread exposure to chlorination by-products that remain in drinking and recreational water worldwide. Despite the demonstrated carcinogenicity in animals of several chlorination by-products, little is known about their potential risks on human health. This study makes a significant contribution to the search for environmental factors involved in the etiology of CLL and to the evidence of the health impact of these high prevalent water contaminants.
The degree of success of river water diversion planning decisions is affected by uncertain environmental conditions. The adaptive water management framework incorporates this uncertainty at all stages of management. While the most effective form of adaptive management requires experimental comparison of practices, the use of optimization modeling is convenient for conducting exploratory simulations to evaluate the spatiotemporal implications of current water diversion management decisions under future environmental changes. We demonstrate such an explorative modeling approach by assessing river water availability for diversion in a river basin in Northern Spain under two future environmental scenarios that combine climate and land use change. An evolutionary optimization method is applied to identify and reduce trade-offs with Supporting Ecosystem Services linked to environmental flow requirements for relevant local freshwater species. The results show that seasonal shifts and spatial heterogeneity of diversion volumes are the main challenges for the future diversion management of the Pas River. Basin-scale diversion management should take into account the seasonal planning horizon and the setting of tailored diversion targets at the local-level to promote the implementation of adaptive management. The presented assessment can help with strategic placement of diversion points and timing of withdrawals, but it also provides deeper insight into how optimisation can support decision-making in managing water diversion under uncertain future environmental conditions.
The aim of this work is to develop a new estuarine classification attending to their vertical structure by examining the advantages and disadvantages of the existing classifications. For this purpose, we reviewed the main classifications, finding that most of them analyze the entire estuary as a unique water body without considering the spatiotemporal variability of the mixing zone in estuaries. Furthermore, the proposed classifications require the calculation of parameters that are not easily measurable, such as tidal current amplitude. Thus, we developed a new classification based on density profile slopes of the water column, which has been correlated to the potential energy anomaly. To test this classification, the proposed method was applied to the Suances estuary (Spain) during the year 2020 and to analyze the potential estuarine modifications under four climate change projections (RCP 4.5 and 8.5 for the years 2050 and 2100). To carry out this study, a calibrated and validated high-resolution horizontal and vertical 3D model was used. The application showed a high variability in the vertical structure of the estuary due to the tide and river. According to the proposed classification, the well mixed category was predominant in the estuary in 2020 and tended to grow in the projections of climate change. As a result, the fully mixed and weakly stratified mixing classes were reduced in the projected scenarios due to a decrease of external forcing, such as river flow and sea level rise. Furthermore, areas classified as stratified tended to move upstream of the estuary.
The objective of this chapter is to analyze if there are similarities on the effects of online shopping channel attributes and perceived risks on online shopping intention among shoppers from Ecuador and Perú. For this purpose, a survey has been applied to Bachelor students from both countries for evaluating their behavior on fashion online shopping. The hypotheses were tested by applying a multigroup PLS-SEM analysis. The results show that convenience and perceived risks are the factors that explain online shopping behavior. It has also been found a significant effect of institutional trust on perceived risk. But, contrary to expectations, higher perceived risks and higher institutional trust resulted in higher perceived risks of online shopping. However, institutional trust has a low explicative and predictive relevance. As a result of multigroup analysis, it seems that there are no significant differences between the two countries, but the external model assessment and the MICOM and PLSpredict analysis indicate that the path-model analysis must be performed separately for each country.
Early and intensive treatment of type 2 diabetes (T2D) has been associated with lower risk of diabetes-related complications. Control of overweight and obesity, which are strongly associated with T2D and many of its complications, is also key in the management of the disease. New therapies allow for individualised glycaemic control targets with greater safety. Thus, in patients with a higher cardiovascular and renal risk profile, current guidelines encourage early treatment with metformin together with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and sodium-glucose co-transporter-2 inhibitors with proven cardiovascular benefit. GLP-1 RAs combine highly efficacious glucose-lowering activity with a reduced risk of hypoglycaemia. Recently, tirzepatide, a first-in-class drug that activates both glucose-dependent insulinotropic polypeptide and GLP-1 receptors, has demonstrated very high efficacy in glycated haemoglobin (HbA1c) and weight reduction in clinical trials. Tirzepatide has the potential to help people with T2D reach recommended glycaemic and weight targets (HbA1c < 7% and > 5% weight reduction) and to allow some patients to reach HbA1c measurements close to normal physiological levels and substantial weight reduction. In 2022, tirzepatide was approved by the US Food and Drug Administration and the European Medicines Agency for treatment of people with T2D and is currently in development for chronic weight management.
Two α-β brass alloys with varying Zn contents have been studied. The samples received for examination were heat-treated at 500 °C in order to conduct dezincification studies according to EN ISO 6509-1 and to measure the depth of dezincification from metallographic sections. According to the phase diagram, the α-phase content should increase as a result of heat-treatment at 500 °C. This phenomenon, however, is difficult to observe in the metallographic sections which were prepared from the heattreated samples. When analyzing the depth of dezincification, it was found that reduced dezincification occurred in the heat-treated samples. This is plausible since β brass is attacked by preferential corrosion. Not only was uniform layer dezincification observed in the brass alloy with the higher Zn content, but also the onset of plug dezincification. This is associated with the original microstructure of the brass which is characterized by a coarse primary grain size. In this alloy, it is clearly observed that larger areas containing alpha brass will impede the process of dezincification.
The use of 3D printed composites in structural applications beyond current prototyping applica-tions requires defining safe and robust methodologies for the determination of critical loads. Taking into account that notches (corners, holes, grooves, etc.) are unavoidable in structural components, the presence of this kind of stress risers affects the corresponding load carrying capacity. This work applies the Point Method (PM) to the estimation of critical (fracture) loads of graphene reinforced polylactic acid (PLA-Gr) plates obtained by fused deposition modeling (FDM), with fixed raster orientation at 45/-45. The plates, additionally, contain three different notch types (U-notches, V-notches and circular holes) and comprise various thicknesses (from 5 mm up to 20 mm) and notch length to plate width ratios (a/W= 0.25 and a/W=0.50). The com-parison between the obtained experimental critical loads and the corresponding estimations de-rived from the application of the PM reveal that this approach generates reasonable accuracy in this particular material, comparable to that obtained in other structural materials obtained from traditional manufacturing processes.
This paper addresses the estimation of critical loads in FFF (Fused Filament Fabrication) printed polymers and composites containing notches. Particularly, the analysis is focused on the fracture load estimations of 39 PLA (polylactic acid) and 39 graphene reinforced PLA (PLA-Gr) printed plates containing two different types of notches (U- and V-notches) and combining different plate thicknesses and defect length to plate width (a/W) ratios. The addition of graphene (1 wt.%) increases both the yield stress and the ultimate tensile strength, also reducing the strain at rupture and, thus, generating a material whose behavior is closer to linear-elasticity. Among the different assessment tools that may be used to estimate critical loads, this work applies the well-known Averaged Strain Energy Density (ASED) criterion, which compares the averaged strain energy over a certain control volume at the notch tip with the corresponding critical value, the latter being a material property. This approach has linear-elastic nature, so its application to non-fully linear materials may require the use of specific corrections or calibrations. For the two materials analyzed here, PLA and PLA-Gr, it has been observed that the ordinary linear-elastic ASED criterion provides good estimations for the PLA-Gr material, whereas the pristine PLA, with more evident non-linear behavior, the obtainment of accurate results requires a previous specific calibration of the ASED material parameters
Background: Over the past two decades, various research teams have designed and applied instruments to measure the quality of life of families with a member who has a disability. A recent systematic review on the state of the Family Quality of Life in early care identified that many of these studies collected data only from the mothers. The present study aimed to investigate whether there is a bias in participant selection in these types of studies. Method: A systematic review of the scientific literature was conducted in three databases—Scopus, Web of Science, Eric—from 2000 to 2022. A total of 72 empirical studies were identified. Results: The findings indicate that most studies examining the Family Quality of Life were based on the information of a single informant per family unit. The profiles of participants according to the research objective are quite similar. In one-third of studies, the authors reported that family members who participate cannot be represented by only mothers or one participant per household. Conclusions: Given the dynamic and collective nature of the construct, the application of a systemic approach is necessary.
Background Prosthetic valve endocarditis (PVE) is a serious infection associated with high mortality that often requires surgical treatment.Methods Study on clinical characteristics and prognosis of a large contemporary prospective cohort of prosthetic valve endocarditis (PVE) that included patients diagnosed between January 2008 and December 2020. Univariate and multivariate analysis of factors associated with in-hospital mortality was performed.ResultsThe study included 1354 cases of PVE. The median age was 71 years with an interquartile range of 62-77 years and 66.9% of the cases were male. Patients diagnosed during the first year after valve implantation (early onset) were characterized by a higher proportion of cases due to coagulase-negative staphylococci and Candida and more perivalvular complications than patients detected after the first year (late onset). In-hospital mortality of PVE in this series was 32.6%; specifically, it was 35.4% in the period 2008-2013 and 29.9% in 2014-2020 (p = 0.031). Variables associated with in-hospital mortality were: Age-adjusted Charlson comorbidity index (OR: 1.15, 95% CI: 1.08-1.23), intracardiac abscess (OR:1.78, 95% CI:1.30-2.44), acute heart failure related to PVE (OR: 3. 11, 95% CI: 2.31-4.19), acute renal failure (OR: 3.11, 95% CI:1.14-2.09), septic shock (OR: 5.56, 95% CI:3.55-8.71), persistent bacteremia (OR: 1.85, 95% CI: 1.21-2.83) and surgery indicated but not performed (OR: 2.08, 95% CI: 1.49-2.89). In-hospital mortality in patients with surgical indication according to guidelines was 31.3% in operated patients and 51.3% in non-operated patients (p
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
Universidad de Cantabria, Avda. de Los Castros, s/n, E-39005, Santander, Cantabria, Spain
Head of institution
Rec. Mag. Ángel Pazos Carro
+34 942 201500