Prácticas en la enseñanza de las ciencias. Problemas y posibilidades

We have effected an analysis of the role attached to practical studies in teaching sciences through the study of works published on this subjetc. The work has been structured starting from the historic development, to go on with the ends and advantages and finishing it outstanding some of the aspects of what can be considered the core of practical work. Finally, we highlight the main objectives to establish these practical classes

Presentation. Reason, reasoning and action: puzzling out the mark of Anscombe.

Nota editorial.Editorial note

Assessing the uncertainty on particle size and shape: implications for ESR and OSL dating of quartz and feldspar grains

Grain size and shape are two important parameters in Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) dating of sediment, since they have a direct impact on several correction factors that are used for evaluating the dose rate. These parameters were evaluated by static image analysis for a wide range of quartz and feldspar grain samples. Our results indicate that there are many factors that may influence the final grain size and shape. Overall, grains are not perfect spheres, but should be rather approximated to smooth slightly elongated ellipsoids, with a width that is on average about 25% smaller than the length. For multiple grains dating, this may have an influence of a few percents on the beta dose rate evaluation, and thus even less on the total dose rate. However, in the case of single grain dating, the impact may be somewhat more significant given the large variability in size and shape between grains that may be encountered in a natural sediment. For beta micro-dosimetry purpose, it may be thus useful to better characterize the single grain that is going to be dated.This study was partially sponsored by a project from the Spanish Ministry of Science and Innovation (Grant number: CGL2010-16821). MD is currently the recipient of an International Outgoing Fellowship from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement PIOF-GA-2013-626474. IC is the beneficiary of a PhD scholarship from the Spanish MINECO (project CGL2012-38434-C03-02)

The effects of cocaine self-administration on dendritic spine density in the rat hippocampus are dependent on genetic background

Chronic exposure to cocaine induces modifications to neurons in the brain regions involved in addiction. Hence, we evaluated cocaine-induced changes in the hippocampal CA1 field in Fischer 344 (F344) and Lewis (LEW) rats, 2 strains that have been widely used to study genetic predisposition to drug addiction, by combining intracellular Lucifer yellow injection with confocal microscopy reconstruction of labeled neurons. Specifically, we examined the effects of cocaine self-administration on the structure, size, and branching complexity of the apical dendrites of CA1 pyramidal neurons. In addition, we quantified spine density in the collaterals of the apical dendritic arbors of these neurons. We found differences between these strains in several morphological parameters. For example, CA1 apical dendrites were more branched and complex in LEW than in F344 rats, while the spine density in the collateral dendrites of the apical dendritic arbors was greater in F344 rats. Interestingly, cocaine self-administration in LEW rats augmented the spine density, an effect that was not observed in the F344 strain. These results reveal significant structural differences in CA1 pyramidal cells between these strains and indicate that cocaine self-administration has a distinct effect on neuron morphology in the hippocampus of rats with different genetic backgrounds

Ethnicity associated microbial and metabonomic profiling in newly diagnosed ulcerative colitis

Introduction: Ulcerative colitis (UC) differs across geography and ethnic groups. Gut microbial diversity plays a pivotal role in disease pathogenesis and differs across ethnic groups. The functional diversity in microbial-driven metabolites may have a pathophysiologic role and offer new therapeutic avenues. Methods: Demographics and clinical data were recorded from newly diagnosed UC patients. Blood, urine and faecal samples were collected at three time points over one year. Bacterial content was analysed by 16S rRNA sequencing. Bile acid profiles and polar molecules in three biofluids were measured using liquid-chromatography mass spectrometry (HILIC) and nuclear magnetic resonance spectroscopy. Results: We studied 42 patients with a new diagnosis of UC (27 South Asians; 15 Caucasians) with 261 biosamples. There were significant differences in relative abundance of bacteria at the phylum, genus and species level. Relative concentrations of urinary metabolites in South Asians were significantly lower for hippurate (positive correlation for Ruminococcus) and 4-cresol sulfate (Clostridia) (p<0.001) with higher concentrations of lactate (negative correlation for Bifidobacteriaceae). Faecal conjugated and primary conjugated bile acids concentrations were significantly higher in South Asians (p=0.02 and p=0.03 respectively). Results were unaffected by diet, phenotype, disease severity and ongoing therapy. Comparison of time points at diagnosis and at 1 year did not reveal changes in microbial and metabolic profile. Conclusion: Ethnic-related microbial metabolite associations were observed in South Asians with UC. This suggests a predisposition to UC may be influenced by environmental factors reflected in a distinct gene-environment interaction. The variations may serve as markers to identify risk factors for UC and modified to enhance therapeutic response

Mid-regional pro-adrenomedullin as a supplementary tool to clinical parameters in cases of suspicion of infection in the emergency department

Introduction: Mid-regional proadrenomedullin (MR-proADM), a novel biomarker, has recently gained interest particularly with regards to its potential in assisting clinicians\u2019 decision making in patients with suspicion of infection in the emergency department (ED). A group of international experts, with research and experience in MR-proADM applications, produced this review based on their own experience and the currently available literature. Areas covered: The review provides evidence related to MR-proADM as a triaging tool in avoiding unnecessary admissions to hospital and/or inadequate discharge, and identifying patients most at risk of deterioration. It also covers the use of MR-proADM in the context of COVID-19. Moreover, the authors provide a proposal on how to incorporate MR-proADM into patients\u2019 clinical pathways in an ED setting. Expert opinion: The data we have so far on the application of MR-proADM in the ED is promising. Incorporating it into clinical scoring systems may aid the clinician\u2019s decision making and recognizing the \u2018ill looking well\u2019 and the \u2018well looking ill\u2019 sooner. However there are still many gaps in our knowledge especially during the ongoing COVID-19 waves. There is also a need for cost-effectiveness analysis studies especially in the era of increasing cost pressures on health systems globally

The Impact of Almonds and Almond Processing On Gastrointestinal Physiology, Luminal Microbiology and Gastrointestinal Symptoms: a Randomized Controlled Trial and Mastication Study.

BACKGROUND: Almonds contain lipid, fiber and polyphenols and possess physicochemical properties that impact nutrient bioaccessibility, which are hypothesized to impact gut physiology and microbiota. OBJECTIVES: Investigate the impact of whole almonds and ground almonds (almond flour) on fecal bifidobacteria (primary outcome), gut microbiota composition and transit time. DESIGN: Healthy adults (n = 87) participated in a parallel, 3-arm randomized controlled trial. Participants received whole almonds (56 g/d), ground almonds (56 g/d) or an isocaloric control muffin in place of habitual snacks for 4 weeks. Gut microbiota composition and diversity (16S rRNA gene sequencing), short-chain fatty acids (gas-chromatography), volatile organic compounds (gas-chromatography mass-spectrometry), gut transit time (wireless motility capsule), stool output and gut symptoms (7-day diary) were measured at baseline and endpoint. The impact of almond form on particle size distribution (PSD) and predicted lipid release was measured in a subgroup (n = 31). RESULTS: Modified intention-to-treat analysis was performed on 79 participants. There were no significant differences in abundance of fecal bifidobacteria following consumption of whole almonds (8.7%, SD 7.7%), ground almonds (7.8%, SD 6.9%) or control (13.0%, SD 10.2%; q = 0.613). Consumption of almonds (whole and ground pooled) resulted in higher butyrate (24.1 μmol/g, SD 15.0 μmol/g) in comparison to control (18.2 μmol/g, SD 9.1 μmol/g; p = 0.046). There was no effect of almonds on gut microbiota at the phylum level or diversity, gut transit time, stool consistency or gut symptoms. Almond form (whole versus ground) had no effect on study outcomes. Ground almonds resulted in significantly smaller PSD and higher predicted lipid release (10.4%, SD 1.8%) in comparison to whole almonds (9.3%, SD 2.0%; p = 0.017). CONCLUSIONS: Almond consumption has limited impact on gut microbiota composition but increases butyrate concentrations in adults, suggesting positive alterations to microbiota functionality. Almonds can be incorporated into the diet to increase fiber consumption without triggering gut symptoms. Clinical trial registry: ClinicalTrials.gov identifier - NCT03581812

Quantifying hydrofluoric acid etching of quartz and feldspar coarse grains based on weight loss estimates: implication for ESR and luminescence dating studies

A series of hydrofluoric (HF) acid etching experiments were performed on several 50 to 300 μm (nominal sieve opening) quartz and feldspar samples, and average etching thicknesses were subsequently determined from weight loss estimates, following the approach of Bell & Zimmerman (1978). Our results are consistent with previous studies and confirm that both HF experimental conditions (etching time, HF concentration, agitation) and the nature/origin of the minerals have a significant effect on etching rate and magnitude. For the samples considered in this study, the outer 10 μm of quartz (i.e., the usual etching target in most ESR and luminescence dating studies) was removed with 40% HF after 40 min of etching, in fair agreement with previous studies. Similar etching results were achieved in just over 20 min when the quartz samples were constantly agitated during 40% HF treatment. For K-feldspars, 10% HF etching for between 10 and 40 min was required to remove the same thickness, although some variability in etching efficiency was evident between different samples and experimental conditions. For a given experimental setup, the overall variability in etching thickness among quartz samples was found to be of at least 20% after 40– 60 min with 40% HF, and can be as high as ∼35%. A set of 14 K-feldspars from a single site revealed an inherent variability of 14% in etching thickness. As a first order approximation, these data may provide useful insights into the expected variability among samples of different origin and from a given area, respectively. However, we recommend that each laboratory evaluates etching thickness losses for their specific HF experimental setup. Additionally, our results show that the 10 μm etching usually considered in ESR and luminescence dating studies may reduce the alpha contribution of the total dose rate to <5%. Although relatively small, this contribution is nevertheless non-negligible. Based on these results, it may be worth considering an additional alpha dose rate term as part of the ESR and luminescence age calculation when etching depths are < 15 μm.M. Duval, V. Guilarte, I. Campaña, L.J. Arnold, L. Miguens, J. Iglesias, S. Gonzàlez-Sierr