Out-of-school experience categories influencing interest in biology of secondary school students by gender: exploration on an Abu Dhabi sample

This study employed the international Relevance of Science Education questionnaire to survey the interest in biology and the out-of-school experiences of Abu Dhabi secondary school students (median age 17, mean age 17.53 and mode age of 16) in the third semester of 2014. It included 3100 participants. An exploratory factor analysis was used to categorise the items for both interest in biology and out-of-school experience. Ten interest in biology and 12 out-of-school experience factors were extracted. The summated means for each factor indicated that ‘health and fitness’ and ‘disease control’ enjoyed highest interests among students. For out-of-school experiences, the two factors of ‘digital applications’ and ‘medical treatment’ received the highest scores. Multivariate analysis of variance revealed that all factors for both interest in biology and out-of-school experience exhibited significant differences between boys and girls. More girls than boys were interested in disease control, reproduction (human biology), alternative science, health and fitness, zoology, and applied cosmetic biology. No significant differences were observed for the remaining five other categories. Furthermore, analysis of variance revealed significant differences between boys and girls with regard to individual items comprising each of the factors. The highest correlations were between the two factors of out-of-school experiences of ‘the natural world’ and ‘learning through observation’ and the interest in biology factor related to ‘plant and animal farming and agriculture’. Results suggested that more emphasis must be placed on students’ out-of-school experience and their engagement in informal learning in contextual outdoor environments to enhance their interest in learning more about biology and the living environment in general.     

Relationship of lower limb height to sitting height in black populations of Africa and the United States.

This article examines a recently reported generalization. Materials from more than a score of invetigations are drawn upon. These materials show there is not a substantial research base for the claim that interbreeding in the United States between black people of African ancestry and white people of European ancestry has resulted in increased lower limb height relative to sitting height.     

Contrast-FEL—A Test for Differences in Selective Pressures at Individual Sites among Clades and Sets of Branches

A number of evolutionary hypotheses can be tested by comparing selective pressures among sets of branches in a phylogenetic tree. When the question of interest is to identify specific sites within genes that may be evolving differently, a common approach is to perform separate analyses on subsets of sequences and compare parameter estimates in a post hoc fashion. This approach is statistically suboptimal and not always applicable. Here, we develop a simple extension of a popular fixed effects likelihood method in the context of codon-based evolutionary phylogenetic maximum likelihood testing, Contrast-FEL. It is suitable for identifying individual alignment sites where any among the K≥2 sets of branches in a phylogenetic tree have detectably different ω ratios, indicative of different selective regimes. Using extensive simulations, we show that Contrast-FEL delivers good power, exceeding 90% for sufficiently large differences, while maintaining tight control over false positive rates, when the model is correctly specified. We conclude by applying Contrast-FEL to data from five previously published studies spanning a diverse range of organisms and focusing on different evolutionary questions.     

Discrimination reversal learning reveals greater female behavioural flexibility in guppies

Behavioural flexibility allows an animal to adapt its behaviour in response to changes in the environment. Research conducted in primates, rodents and domestic fowl suggests greater behavioural persistence and reduced behavioural flexibility in males. We investigated sex differences in behavioural flexibility in fish by comparing male and female guppies (Poecilia reticulata) in a reversal learning task. Fish were first trained on a colour discrimination, which was learned equally rapidly by males and females. However, once the reward contingency was reversed, females were better at inhibiting the previous response and reached criterion twice as fast as males. When reward reversing was repeated, males gradually reduced the number of errors, and the two sexes had a comparable performance after four reversals. We suggest that sex differences in behavioural flexibility in guppies can be explained in terms of the different roles that males and females play in reproduction.     

Photosynthesis,Transpiration, and Water Use Efficiency of Vegetative and Reproductive Shoots of Grassland Species from North-Eastern China

The differences in net photosynthetic rate (P _N), transpiration rate (E), and water use efficiency (WUE) between the vegetative and reproductive shoots of three native grass species from the grassland of northeastern China [grey-green and yellow green populations of Leymus chinensis (Trin.) Tzvel., Puccinellia tenuiflora (Griseb) Scrib & Merr, Puccinellia chinampoensis Ohwi] were compared. The two type shoots experienced similar habitats, but differed in leaf life-span and leaf area. The leaf P _N and WUE for the vegetative shoots were significantly higher than those for the reproductive shoots in the grasses, while their E were remarked lower in the dry season. Relative lower leaf P _N and WUE for the reproductive shoots of grassland grasses may explain the facts of lower seed production and the subordinate role of seed in the grassland renewal in north-eastern China.     

Within-tree spatial variation in the leaf monoterpenes of Sequoia sempervirens

Location within a tree was analyzed as a source of variation in Sequoia sempervirens leaf monoterpenes. No differences were found for quantitative composition or total yield/dry wt among lower, middle and upper canopy positions. The awlshaped, spirally arranged leaves of vigorous upper shoots showed small quantitative compositional differences, but not differences in total yield. The intermediate leaf form of young sprouts had the most different monoterpene quantitative composition and about three times the total yield of the above two leaf forms. Analysis of a clonal ring of 17 adult trees resulted in coefficients of variation similar to those for samples collected from different canopy levels of the same shoot. Results revealed the sources and magnitudes of experimental error in comparative studies of this species' leaf monoterpenes, and did not support the concept that somatic mutation provides an important source of variation in a large, long-lived organism such as coast redwood.     

Kinetic characterization of rat liver nuclear lysozyme

The kinetic properties of rat liver nuclear lysozyme, earlier purified to homogeneity in our laboratory, have been studied. The enzyme was found to be maximally active in the pH range 4.2 to 5.4 in 0.02 M buffer. Its Km was found to be 333 mg/litre. It was heat sensitive even in the acidic pH range. The enzyme exhibited tissue specific differences when compared with the rat kidney nuclear lysozyme.     

Sex differences in leg dexterity are not present in elite athletes

We studied whether the time-varying forces that control unstable foot–ground interactions provide insight into the neural control of dynamic leg function. Twenty elite (10 F, 26.4 ± 3.5 yrs) and 20 recreational (10 F, 24.8 ± 2.4 yrs) athletes used an isolated leg to maximally compress a slender spring designed to buckle at low forces while seated. The foot forces during the compression at the edge of instability quantify the maximal sensorimotor ability to control dynamic foot–ground interactions. Using the nonlinear analysis technique of attractor reconstruction, we characterized the spatial (interquartile range IQR) and geometric (trajectory length TL, volume V, and sum of edge lengths SE) features of the dynamical behavior of those force time series. ANOVA confirmed the already published effect of sex, and a new effect of athletic ability, respectively, in TL (p = 0.014 and p < 0.001), IQR (p = 0.008 and p < 0.001), V (p = 0.034 and p = 0.002), and SE (p = 0.033 and p < 0.001). Further analysis revealed that, for recreational athletes, females exhibited weaker corrective actions and greater stochasticity than males as per their greater mean values of TL (p = 0.003), IQR (p = 0.018), V (p = 0.017), and SE (p = 0.025). Importantly, sex differences disappeared in elite athletes. These results provide an empirical link between sex, athletic ability, and nonlinear dynamical control. This is a first step in understanding the sensorimotor mechanisms for control of unstable foot–ground interactions. Given that females suffer a greater incidence of non-contact knee ligament injuries, these non-invasive and practical metrics of leg dexterity may be both indicators of athletic ability, and predictors of risk of injury.     

Inferring patterns of aggression from red howler monkey injuries

Venezuelan red howler monkeys in a semideciduous habitat typically survive injuries and disabilities. Intraspecific physical aggression was the most frequently observed and inferred cause of injury. Thirty-eight percent of 119 howlers of all ages examined during capture had scars or other evidence of “damage.” Overall, the sexes did not differ significantly in total number of injuries or number of individuals classified as “damaged.” The incidence of injury was not independent of age-sex class. The subadult male class had the highest percentage of “damaged” individuals. However, when total injuries per age class were examined for each sex separately, only females showed a pattern that was significantly different than expected based on age (i.e., exposure to injury factors). Subadult females experienced more injuries than expected, whereas adult females had fewer injuries. Troop status (resident troop, natal troop, or extratroop) was not significantly related to the number of injuries in adult and subadult males. Thin finding was not surprising, because adult and subadult males of all status classes are involved in aggression related to breeding competition. Extratroop females had more injuries than expected, and natal females had the fewest injuries. The higher incidence of injuries on subadult females and extratroop females is consistent with aggression-mediated emigration of some females and observed resistance to female immigration by resident females. Overall, 74% of injuries were located on anterior-ventral portions of the body, consistent with the face-to-face fighting observed in howlers. Sociobiological costs of aggression in red howlers are difficult to assess because many howlers, despite frequent and severe injury, subsequently survive and reproduce. We recommend caution in inferring mortality from injuries, especially when social mobility and emigration out of the study area are common.