El trabajo de la fuerza de fricción en libros de texto universitarios

Considerando una revisión de la literatura relacionada con la enseñanza de la física, estamos desarrollando una investigación que analiza cómo se presenta el trabajo de las fuerzas de roce y sus relaciones con el teorema de trabajo y energía, en libros de texto de nivel universitario básico. Si bien algunos artículos ampliamente citados destacan aspectos relevantes que deberían ser considerados en el tratamiento del tema y han sido publicados hace más de dos décadas, encontramos textos que no se han hecho eco de los mismos, otros que introducen modificaciones parciales y pocos que reflejan explícitamente los cambios sugeridos. Las tendencias mencionadas se ilustran considerando tres textos de uso muy difundido en nuestro ámbito

El trabajo de la fuerza de fricción en libros de texto universitarios

Considerando una revisión de la literatura relacionada con la enseñanza de la física, estamos desarrollando una investigación que analiza cómo se presenta el trabajo de las fuerzas de roce y sus relaciones con el teorema de trabajo y energía, en libros de texto de nivel universitario básico. Si bien algunos artículos ampliamente citados destacan aspectos relevantes que deberían ser considerados en el tratamiento del tema y han sido publicados hace más de dos décadas, encontramos textos que no se han hecho eco de los mismos, otros que introducen modificaciones parciales y pocos que reflejan explícitamente los cambios sugeridos. Las tendencias mencionadas se ilustran considerando tres textos de uso muy difundido en nuestro ámbito

Delayed Care and Mortality Among Women and Men with Myocardial Infarction

Background-Women with ST-segment-elevation myocardial infarction (STEMI) have higher mortality rates than men. We investigated whether sex-related differences in timely access to care among STEMI patients may be a factor associated with excess risk of early mortality in women. Methods and Results-We identified 6022 STEMI patients who had information on time of symptom onset to time of hospital presentation at 41 hospitals participating in the ISACS-TC (International Survey of Acute Coronary Syndromes in Transitional Countries) registry (NCT01218776) from October 2010 through April 2016. Patients were stratified into time-delay cohorts. We estimated the 30-day risk of all-cause mortality in each cohort. Despite similar delays in seeking care, the overall time from symptom onset to hospital presentation was longer for women than men (median: 270 minutes [range: 130-776] versus 240 minutes [range: 120-600]). After adjustment for baseline variables, female sex was independently associated with greater risk of 30-day mortality (odds ratio: 1.58; 95% confidence interval, 1.27-1.97). Sex differences in mortality following STEMI were no longer observed for patients having delays from symptom onset to hospital presentation of (odds ratio: 0.77; 95% confidence interval, 0.29-2.02). Conclusions-Sex difference in mortality following STEMI persists and appears to be driven by prehospital delays in hospital presentation. Women appear to be more vulnerable to prolonged untreated ischemia

Neutrophilia, lymphopenia and myeloid dysfunction: A living review of the quantitative changes to innate and adaptive immune cells which define COVID-19 pathology

Destabilisation of balanced immune cell numbers and frequencies is a common feature of viral infections. This occurs due to, and further enhances, viral immune evasion and survival. Since the discovery of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), which manifests in coronavirus disease 2019 (COVID-19), a great number of studies have described the association between this virus and pathologically increased or decreased immune cell counts. In this review, we consider the absolute and relative changes to innate and adaptive immune cell numbers, in COVID-19. In severe disease particularly, neutrophils are increased, which can lead to inflammation and tissue damage. Dysregulation of other granulocytes, basophils, and eosinophils represent an unusual COVID-19 phenomenon. Contrastingly, the impact on the different types of monocytes leans more strongly to an altered phenotype, e.g. HLA-DR expression, rather than numerical changes. However, it is the adaptive immune response which bears the most profound impact of SARS-CoV-2 infection. T cell lymphopenia correlates with increased risk of ICU admission and death; therefore, this parameter is particularly important for clinical decision making. Mild and severe disease differ in the rate of immune cell counts returning to normal levels post disease. Tracking the recovery trajectories of various immune cell counts may also have implications for long-term COVID-19 monitoring. This review represents a snapshot of our current knowledge, showing that much has been achieved in a short period of time. Alterations in counts of distinct immune cells represent an accessible metric to inform patient care decision or predict disease outcomes

Risk prediction of late-onset Alzheimer’s disease implies an oligogenic architecture

Genetic association studies have identified 44 common genome-wide significant risk loci for late-onset Alzheimer's disease (LOAD). However, LOAD genetic architecture and prediction are unclear. Here we estimate the optimal P-threshold (P) of a genetic risk score (GRS) for prediction of LOAD in three independent datasets comprising 676 cases and 35,675 family history proxy cases. We show that the discriminative ability of GRS in LOAD prediction is maximised when selecting a small number of SNPs. Both simulation results and direct estimation indicate that the number of causal common SNPs for LOAD may be less than 100, suggesting LOAD is more oligogenic than polygenic. The best GRS explains approximately 75% of SNP-heritability, and individuals in the top decile of GRS have ten-fold increased odds when compared to those in the bottom decile. In addition, 14 variants are identified that contribute to both LOAD risk and age at onset of LOAD

Heart re-transplantation in Eurotransplant

Internationally 3% of the donor hearts are distributed to re-transplant patients. In Eurotransplant, only patients with a primary graft dysfunction (PGD) within 1 week after heart transplantation (HTX) are indicated for high urgency listing. The aim of this study is to provide evidence for the discussion on whether these patients should still be allocated with priority. All consecutive HTX performed in the period 1981-2015 were included. Multivariate Cox' model was built including: donor and recipient age and gender, ischaemia time, recipient diagnose, urgency status and era. The study population included 18 490 HTX, of these 463 (2.6%) were repeat transplants. The major indications for re-HTX were cardiac allograft vasculopathy (CAV) (50%), PGD (26%) and acute rejection (21%). In a multivariate model, compared with first HTX hazards ratio and 95% confidence interval for repeat HTX were 2.27 (1.83-2.82) for PGD, 2.24 (1.76-2.85) for acute rejection and 1.22 (1.00-1.48) for CAV (P < 0.0001). Outcome after cardiac re-HTX strongly depends on the indication for re-HTX with acceptable outcomes for CAV. In contrast, just 47.5% of all hearts transplanted in patients who were re-transplanted for PGD still functioned at 1-month post-transplant. Alternative options like VA-ECMO should be first offered before opting for acute re-transplantation

Reperfusion therapy for ST elevation acute myocardial infarction in Europe: description of the current situation in 30 countries

Aims Patient access to reperfusion therapy and the use of primary percutaneous coronary intervention (p-PCI) or thrombolysis (TL) varies considerably between European countries. The aim of this study was to obtain a realistic contemporary picture of how patients with ST elevation myocardial infarction (STEMI) are treated in different European countries. Methods and results The chairpersons of the national working groups/societies of interventional cardiology in European countries and selected experts known to be involved in the national registries joined the writing group upon invitation. Data were collected about the country and any existing national STEMI or PCI registries, about STEMI epidemiology, and treatment in each given country and about PCI and p-PCI centres and procedures in each country. Results from the national and/or regional registries in 30 countries were included in this analysis. The annual incidence of hospital admission for any acute myocardial infarction (AMI) varied between 90–312/100 thousand/year, the incidence of STEMI alone ranging from 44 to 142. Primary PCI was the dominant reperfusion strategy in 16 countries and TL in 8 countries. The use of a p-PCI strategy varied between 5 and 92% (of all STEMI patients) and the use of TL between 0 and 55%. Any reperfusion treatment (p-PCI or TL) was used in 37–93% of STEMI patients. Significantly less reperfusion therapy was used in those countries where TL was the dominant strategy. The number of p-PCI procedures per million per year varied among countries between 20 and 970. The mean population served by a single p-PCI centre varied between 0.3 and 7.4 million inhabitants. In those countries offering p-PCI services to the majority of their STEMI patients, this population varied between 0.3 and 1.1 million per centre. In-hospital mortality of all consecutive STEMI patients varied between 4.2 and 13.5%, for patients treated by TL between 3.5 and 14% and for patients treated by p-PCI between 2.7 and 8%. The time reported from symptom onset to the first medical contact (FMC) varied between 60 and 210 min, FMC-needle time for TL between 30 and 110 min, and FMC-balloon time for p-PCI between 60 and 177 min. Conclusion Most North, West, and Central European countries used p-PCI for the majority of their STEMI patients. The lack of organized p-PCI networks was associated with fewer patients overall receiving some form of reperfusion therapy