Heat Transfer in Packed Bed Heat Recuperators—I. A Precision Numerical Analysis

An extensive literature survey is reported that verifies the need for a more precise representation of the heat transfer film coefficient in packed beds. A precision numerical analysis scheme is developed for a much more general model than previously reported. Application of the results to the experimental data will be reported in Part II of the paper.     

What mathematical competencies does a citizen need to interpret Mexico’s official information about the COVID-19 pandemic?

Educational Studies in Mathematics - We report a study on mathematical literacy with special emphasis on health literacy. In particular, we identify and characterize the mathematical competencies...     

Under what conditions do firms benefit from the research efforts of other organizations?

Although R&D spillovers play a key role in the battle for technological leadership, it is unclear under what conditions firms build on and benefit from the discoveries of others. The study described here empirically examines this issue. The findings indicate that, depending on technological opportunities, firm size and competitive pressure, the net impact of R&D spillovers on productivity can be either positive or negative. Specifically, we find that although spillover effects are positively associated with the technological opportunities that a firm faces, this relationship is reversed when firm size is considered. Whilst external R&D affects large self-reliant firms negatively, its impact on the productivity of smaller firms (who usually introduce incremental innovations that are characterized by a strong reliance on external technologies) is positive, and even higher than that of their own R&D. We also demonstrate that the economic payoff for firms’ own R&D is lower when they face intense competition. In cases of low-appropriability, however, spillover effects are more positive, allowing firms to increase their performance using the inventions of others.     

Haemoglobin A1c-based screening for prediabetes and diabetes mellitus: a multi-center study in Croatian adult population

IntroductionBased on the hypothesis that there is a substantial rate of adults with prediabetes and undiagnosed diabetes mellitus (DM), our aim was to perform haemoglobin A1c (HbA_1c)-based screening in a cohort of Croatian adults and estimate the prevalence of prediabetes and undiagnosed DM according to American Diabetes Association criteria.Materials and methodsThis multi-center, cross-sectional study performed in six Croatian hospitals included 5527 patients aged 40 to 70 years admitted to the Emergency Department or undergoing a primary care check-up. Haemoglobin A1c was measured from leftover whole blood samples using the enzymatic method on either Alinity c or Architect c-series analyser (Abbott Laboratories, Chicago, USA). Haemoglobin A1c between 39-47 mmol/mol was classified as prediabetes, while ≥ 48 mmol/mol as undiagnosed DM.ResultsAfter exclusion of 435 patients with known DM, the final cohort included 5092 patients (median age 57; 56% males). A total of 882 (17.3%) patients had HbA_1c values between 39 and 47 mmol/mol. There were 214 (4.2%) patients with HbA_1c ≥ 48 mmol/mol. Prediabetes prevalence ranged from 14.2% to 20.5%, while undiagnosed DM from 3.3% to 7.3%, with statistically significant differences among settings (P < 0.001). Age-stratified analysis showed that prediabetes and undiagnosed DM prevalence increase with age (P < 0.001), being 25.4% and 5.8%, respectively, in patients aged 60 to 70 years.ConclusionUnderlying impairment of glucose metabolism was identified in about one in five adults, with significant number of patients with already overt DM. These results should serve as a starting point for further steps directed towards promotion of preventive measures for DM in Croatia.     

Do linkages between farmers and academic researchers influence researcher productivity? The Mexican case

A growing body of literature is focusing on how the collaborations researchers engage in affect their productivity. Most authors have focused on linkages among academic researchers, measuring productivity by the number of papers published in ISI journals. In contrast, the impact of interactions between academic researchers and the business sector on research productivity has been less analyzed. The aim of this paper is to analyze how broadly defined research productivity (papers, new recommendations and new techniques) in agriculture-related fields is affected by the nature of academy-farmers interactions. This latter was approached through two dimensions: the breadth of linkages and their intensity, measured by the duration, in two different modalities (R&D activities and consultancy). Based on original micro data obtained through a survey of researchers working in universities and PRCs in agriculture-related fields, we built three models, one per output, to identify the effect of the nature of interactions on research productivity. The models were estimated with a negative binomial distribution using Maximum Likelihood estimators. We found a positive relationship between interaction with farmers and publishing of papers when interactions are carried out through the R&D modality. We also found that the impact of the nature of interactions on research productivity differs according to the type of research output. The impact is broader in the case of new recommendations than in the other outputs. The production of new recommendations is positively influenced by both the breadth of linkages and their duration through both modalities of interaction (R&D and consultancy).     

Potential adverse cardiac remodelling in highly trained athletes: still unknown clinical significance

Moderate endurance exercise has long been considered an essential element to maintain cardiovascular health, and sedentary behaviour in the general population has been related to a significant increase in all-causes of mortality, cardiovascular disease mortality and cardiovascular disease incidence. However, a growing group of people performs an intense exercise that leads to multiple heart adaptive changes that are collectively called “athlete’s heart”. In this review, we discussed the evidence of cardiac remodelling process secondary to repetitive and strenuous exercise in some predisposed athletes that produces intense and probably deleterious changes in cardiac morphology and function with no clear clinical significance in long-term follow-up. Moreover, we also discussed the individual biological response to exercise assessed by myocardial damage, inflammation, oxidative stress, fibrosis and ventricular hypertrophy biomarkers showing different intensities with equivalent exertion.