Diferencias intraespecíficas en el uso de un vertedero por parte de la Cigüeña Blanca (Ciconia ciconia) en el oeste de la Península Ibérica

Es va estudiar la presència de cigonyes blanques anellades a l'abocador de Càceres durant les temporades de cria de 1989 i 1990. La mitjana més alta del nombre d'ocells es va donar durant l'abril, mentre que al maig va ser el mes amb el menor nombre d'ocells. Els exemplars més joves de quatre anys foren més freqüents i amb proporcions majors del que s'esperava tenint en compte els percentatges de mortalitat d'aquesta espècie. Entre els ocells més joves de quatre anys els més abundants foren els individus d'un any, els quals eren més freqüents de l'esperat. Durant el període d'estudi les cigonyes van estar a l'abocador el mateix temps amb independència de les dues classes d'edats definides. Aquests resultats mostren la importància del menjar addicional per als ocells immadurs

Niveles de razonamiento de estudiantes de secundaria y bachillerato en una situación-problema de probabilidad

En el presente trabajo se explora la manera en que estudiantes de secundaria (14-15 años) y Bachillerato (15-16 años), que no han estudiado probabilidad, resuelven una tarea que involucra algunas nociones básicas de la teoría de probabilidades. El propósito es identificar los rasgos característicos de los niveles de razonamiento que exhiben los estudiantes cuando transitan de la secundaria al Bachillerato frente a una situación-problema de probabilidad. Se utiliza la taxonomía SOLO para organizar las respuestas en niveles estructurales. En general, los estudiantes de Bachillerato muestran un nivel más alto de razonamiento que los estudiantes de secundaria

Alturas de equilibrio de líquidos en celdas de Hele-Shaw corrugadas bajo penetración capilar espontánea = Equilibrium heights of liquids in corrugated Hele-Shaw cells under spontaneous capillary penetration

Se presenta un método simple y general para calcular las alturas de equilibrio de un líquido que penetra espontáneamente, por capilaridad, en una celda de Hele-Shaw vertical y corrugada. La corrugación se impuso sobre cada una de las paredes interiores de las placas que forman la celda como funciones coseno y de esta forma se generan canales periódicos verticales. Se encuentra que esta corrugación determina complejos per.les de equilibrio que pueden ser integrados para estimar los volémenes de líquido absorbido, o del aire (gas) desalojado. Se discuten también resultados para celdas corrugadas con una inclinación respecto a la vertical. A simple and general method to calculate the equilibrium heights of a liquid that penetrates spontaneously, due to capillarity, into a corrugated Hele-Shaw cell is presented. A cosine-like corrugation was imposed on each internal face of the plates that made the cell and periodic channels were generated. It were found complex equilibrium heights which allow to evaluate the volumes of absorbed liquid or expelled gas. Equilibrium heights were also evaluated in corrugated tilted cells

Oscillatory relaxation of zonal flows in a multi-species stellarator plasma

The low frequency oscillatory relaxation of zonal potential perturbations is studied numerically in the TJ-II stellarator (where it was experimentally detected for the first time). It is studied in full global gyrokinetic simulations of multi-species plasmas. The oscillation frequency obtained is compared with predictions based on single-species simulations using simplified analytical relations. It is shown that the frequency of this oscillation for a multi-species plasma can be accurately obtained from single-species calculations using extrapolation formulas. The damping of the oscillation and the influence of the different inter-species collisions is studied in detail. It is concluded that taking into account multiple kinetic ions and electrons with impurity concentrations realistic for TJ-II plasmas allows to account for the values of frequency and damping rate in zonal flows relaxations observed experimentally.Comment: 11 figures, 22 page

Confirmation of symmetrical distributions of clinical attachment loss and tooth loss in a homogeneous Mexican adult male population

Background/purpose To ascertain whether or not clinical attachment loss and tooth loss are present with similar severity and prevalence across the two sides of the mouth in a homogeneous sample of urban male adults. Materials and methods A cross-sectional study was carried out on 161 policemen (a largely homogeneous group in terms of ethnic background, socioeconomic status, sex, occupation, and medical/dental insurance) in Campeche, Mexico. Periodontal examinations were undertaken using the Florida Probe System in a dental chair by one trained and standardized examiner (kappa ≥ 0.60) to determine clinical attachment loss and tooth loss. We examined six sites in all teeth present in the mouth (a maximum of 168 sites, no third molars). Because of correlated data between observations, McNemar (for tooth loss) and Wilcoxon (for attachment loss) signed-rank tests were used to compare right and left sites within the same patient. Results The mean age was 38.4 ± 11.0 years. The mean number of teeth present was 24.4 ± 4.6; the mean number of periodontal sites/person was 146.7 ± 27.8. All P values were ≥ 0.05 (except for attachment loss in the upper first premolars), suggesting that there were no statistically significant differences between the right and left sides for the frequency of presentation of these two conditions. Conclusion Tooth loss and attachment loss measurements largely resemble each other on both sides of the mouth

Some viable models for digital public-interest journalism

The supply of public interest journalism that serves the needs of citizens in a democratic society has always been scarce in the media marketplace when compared with sensationalism, gossip, entertainment, propaganda, and misinformation. This scarce commodity, whose market value lies in its credibility and depends on costly investments of time and money in professional research, has frequently required a subsidy, which for more than a century was provided by advertising. Now that this subsidy has mostly been devoured by technological platforms such as Google and Facebook, the industry and profession are developing new models focused on user needs and wants with a trend toward public service rather than profit. This paper uses deductive and critical methodologies to identify the most promising business models used by media companies to counteract the decline in public-interest journalism. Our proposal is that an appropriate business model can be the best way to revitalize media companies. The research is based on Chesbrough’s business model framework applied to 20 leading digital news publications from 16 countries. In addition, we analyze how Covid-19 has impacted those business models

Effect of zinc intake on growth in infants: A meta-analysis

A systematic review and meta-analysis of available randomized controlled trials (RCTs) was conducted to evaluate the effect of zinc (Zn) intake on growth in infants. Out of 5500 studies identified through electronic searches and reference lists, 19 RCTs were selected after applying the exclusion/inclusion criteria. The influence of Zn intake on growth was considered in the overall meta-analysis. Other variables were also taken into account as possible effect modifiers: doses of Zn intake, intervention duration, nutritional status, and risk of bias. From each select growth study, final measures of weight, length, mid upper arm circumference (MUAC), head circumference, weight for age z-score (WAZ), length for age z-score (LAZ), and weight for length z-score (WLZ) were assessed. Pooled β and 95% confidence interval (CI) were calculated. Additionally, we carried out a sensitivity analysis. Zn intake was not associated with weight, length, MUAC, head circumference, and LAZ in the pooled analyses. However, Zn intake had a positive and statistically effect on WAZ (β = 0.06; 95%CI 0.02 to 0.10) and WLZ (β = 0.05; 95%CI 0.01 to 0.08). The dose–response relationship between Zn intake and these parameters indicated that a doubling of Zn intake increased WAZ and WLZ by approximately 4%. Substantial heterogeneity was present only in length analyses (I2 = 45%; p = 0.03). Zn intake was positively associated with length values at short time (four to 20 weeks) (β = 0.01; CI 95% 0 to 0.02) and at medium doses of Zn (4.1 to 8 mg/day) (β = 0.003; CI 95% 0 to 0.01). Nevertheless, the effect magnitude was small. Our results indicate that Zn intake increases growth parameters of infants. Nonetheless, interpretation of these results should be carefully considered