A reconstruction of development of the periodic table based on history and philosophy of science and its implications for general chemistry textbooks

The objectives of this study are: (a) elaboration of a history and philosophy of science (HPS) framework based on a reconstruction of the development of the periodic table; (b) formulation of seven criteria based on the framework; and (c) evaluation of 57 freshman college‐level general chemistry textbooks with respect to the presentation of the periodic table. The historical reconstruction of the periodic table showed that the periodicity of the elements could be construed as an inductive generalization or as a function of the atomic theory. There is considerable controversy with respect to the nature of Mendeleev's contribution, and various alternatives are discussed: ordered domain; empirical law; and a theory with limited explanatory power. Accommodation of the elements according to their physicochemical properties is considered to be the major contribution of the periodic table by all textbooks, followed by contrapredictions of previously unknown elements (30 textbooks), and novel predictions (corrections of atomic mass) of known elements (10 textbooks). The relative importance of accommodation and prediction within an HPS framework is generally ignored. Few textbooks have attempted to explore the possible cause of periodicity in the table and very few textbooks have explored the nature of Mendeleev's contribution. The development of the periodic table as a sequence of heuristic principles in the form of a convincing argument has been ignored. The textbook approach of emphasizing that the development of the periodic table was an inductive generalization, and that Mendeleev had no model or theory, does not facilitate the spirit of critical inquiry that led the scientists to grapple with alternative interpretations, conflicts, and controversies. It is concluded that the development of the periodic table went through a continual critical appraisal (conflict and controversy), in which scientists presented various tentative theoretical ideas to understand the observed phenomena. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 42: 84–111, 2005     

Research assessment by percentile-based double rank analysis

In the double rank analysis of research publications, the local rank position of a country or institution publication is expressed as a function of the world rank position. Excluding some highly or lowly cited publications, the double rank plot fits well with a power law, which can be explained because citations for local and world publications follow lognormal distributions. We report here that the distribution of the number of country or institution publications in world percentiles is a double rank distribution that can be fitted to a power law. Only the data points in high percentiles deviate from it when the local and world μ parameters of the lognormal distributions are very different. The likelihood of publishing very highly cited papers can be calculated from the power law that can be fitted either to the upper tail of the citation distribution or to the percentile-based double rank distribution. The great advantage of the latter method is that it has universal application, because it is based on all publications and not just on highly cited publications. Furthermore, this method extends the application of the well-established percentile approach to very low percentiles where breakthroughs are reported but paper counts cannot be performed.     

Un estudio sobre la comprensión de términos espacio-temporales en niños de 4 a 6 años

Resumen

Este estudio trató de comprobar si la comprensión de los pares de palabras «antesldespués», «delanteldetrás» y «primerolúltimo» presenta relación con el significado dominante en la comunidad lingüistica, la complejidad de la tarea, la asimetría de los términos y la edad. Se utilizaron 90 adultos y 180 niños entre 4 y 6 años. Los adultos definieron las palabras a analizar; loi niños ejecutaron las consignas en tres contextos: espacial, espacio-temporal y temporal. Los resultados indican que el par «antesldespués» es comprendido más pronto en el sentido temporal, el par «delanteldetrás» en sentido espacial. Estos datos coinciden con los obtenidos en las definiciones adultas. «Primeroúltimo» es mejor comprendido en tareas temporales, aunque los adultos dieron definiciones ambiguas. Por otra parte, la compejidad de la tarea parece influir en la comprensión: l'a ausencia de rasgos de los objetos y. el. orden gramatical inverso dificultan la tarea. Estos resultados sugieren que la hipótesis de los rasgos sonánticos es insuficiente para explicar la adquisición del signifcado.     

Guava extract （Psidium guajava） alters the labelling of blood constituents with technetium-99m

Psidium guajava （guava） leaf is a phytotherapic used in folk medicine to treat gastrointestinal and respiratory disturbances and is used as anti-inflammatory medicine. In nuclear medicine, blood constituents （BC） are labelled with technetium-99m （^99mTc） and used to image procedures. However, data have demonstrated that synthetic or natural drugs could modify the labelling of BC with ^99mTC. The aim of this work was to evaluate the effects of aqueous extract of guava leaves on the labelling of BC with ^99mTc. Blood samples of Wistar rats were incubated with different concentrations of guava extract and labelled with ^99mTc after the percentage of incorporated radioactivity （%ATI） in BC was determined. The results suggest that aqueous guava extract could present antioxidant action and/or alters the membrane structures involved in ion transport into cells, thus decreasing the radiolabelling of BC with ^99mTc. The data showed significant （P〈0.05） alteration of ATI in BC from blood incubated with guava extract.     

Paid maternal leave is associated with infant brain function at 3 months of age

The first months of life are critical for establishing neural connections relevant for social and cognitive development. Yet, the United States lacks a national policy of paid family leave during this important period of brain development. This study examined associations between paid leave and infant electroencephalography (EEG) at 3 months in a sociodemographically diverse sample of families from New York City (N = 80; 53 males; 48% Latine; data collection occurred 05/2018–12/2019). Variable-centered regression results indicate that paid leave status was related to differences in EEG power (ps < .02, R²s > .12). Convergent results from person-centered latent profile analyses demonstrate that mothers with paid leave were 7.39 times as likely to have infants with EEG profiles characterized by increased higher-Hz power (95% CI, 1.9–36.9), potentially reflecting more mature patterns of brain activity.     

Double rank analysis for research assessment

Reliable methods for the assessment of research success are still in discussion. One method, which uses the likelihood of publishing very highly cited papers, has been validated in terms of Nobel prizes garnered. However, this method cannot be applied widely because it uses the fraction of publications in the upper tail of citation distribution that follows a power law, which includes a low number of publications in most countries and institutions. To achieve the same purpose without restrictions, we have developed the double rank analysis, in which publications that have a low number of citations are also included. By ranking publications by their number of citations from highest to lowest, publications from institutions or countries have two ranking numbers: one for their internal and another one for world positions; the internal ranking number can be expressed as a function of the world ranking number. In log–log double rank plots, a large number of publications fit a straight line; extrapolation allows estimating the likelihood of publishing the highest cited publication. The straight line derives from a power law behavior of the double rank that occurs because citations follow lognormal distributions with values of μ and σ that vary within narrow limits.     

Differential thermal expansion as a cause of salt decay: literature review,experiments, and modelling of micro and macro effects on Ançã limestone

Salt decay is one of the harshest, most frequent, and more complex types of decay of porous materials in built heritage, including natural stones, ceramics, and mortars. In this article, we address the mechanism of thermal expansion, which is one of the least studied, yet most controversial, of those proposed over time to explain salt decay. We present a review of scientific literature on the topic, followed by a study of the effects of thermal expansion on a specific material, the well-known Ançã limestone. The study included experimental measurement of the linear thermal expansion coefficient of the Ançã, both in its natural state and with varying contents of sodium chloride, sodium sulphate, or sodium nitrate. The results show that this coefficient: (i) is significantly higher when the stone is contaminated with salt; and (ii) scales approximately with the amount of salt contained in the stone pores, regardless of the type of salt. Based on these results and on modelling of damage modes at the microscopic and macroscopic levels, respectively, we conclude that thermal expansion can cause powdering, disaggregation, or other types of decay consisting of internal loss of cohesion. However, it is not likely to cause exfoliation of salt-loaded layers.     

Prevalence of urinary incontinence in high-impact sports athletes and their association with knowledge,attitude and practice about this dysfunction

Objective: To evaluate the prevalence of urinary incontinence (UI) in female athletes practising high-impact sports and its association with knowledge, attitude and practice (KAP).

Design: Observational study.

Methods: A semi-structured evaluation form, KAP survey and the International Consultation on Incontinence Questionnaire – Short Form were used. Univariate and multivariate analyses were performed to verify the association of UI with KAP, sociodemographic, gynaecological and sports-related variables, with significant variables remaining in the model (p?Results: The prevalence of UI in 118 athletes was 82 (70%), of which 19 (23%) had pure stress UI, 19 (23%) had pure urgency UI and 44 (54%) had mixed UI; with 50 (61%) athletes losing urine during training and 37 (45%) during competitions. Regarding the KAP survey, 37 athletes (31%) demonstrated adequate knowledge, 63 (53%) adequate attitude and zero adequate practice. In the multivariate analysis, a sports practice time of over 8 years and dyspareunia presented significant values, with odds ratios (OR) of 2.66 and 2.99, respectively. Knowledge was significantly associated with UI (OR 0.43). UI had a slight impact on QOL.

Conclusions: There is a high prevalence of UI yet low levels of adequate knowledge and practice regarding the occurrence of UI in sports, with sports practice time over 8 years and dyspareunia factors predisposing female athletes to UI by 2.7 and 3 times, respectively. Athletes with adequate knowledge were 57% less likely to develop UI.