Objectives Using prenatally fixed dermatoglyphics features as markers of prenatal sex development is limited due to insufficient knowledge on their sex differences. This study aims to examine more thoroughly sex differences in radioulnar contrasts. Methods Fingerprints of 360 females and 331 males from four samples of different ethnic backgrounds (Czechs, Slovaks, Vietnamese and Lusatian Sorbs) were studied. On both hands, finger ridge counts were recorded, and all possible radioulnar contrasts were computed as a difference between ridge count at a radial position minus ridge count at a respective ulnar position on the hand. Radioulnar contrasts with population‐congruent and numerically large dimorphism were selected and the dimorphism of the selected radioulnar contrasts was then tested using nonparametric analysis of variance. Results Greater dimorphism of radioulnar contrasts occurred on the right hand than on the left hand. Population congruent direction and relatively strong dimorphism (Cohen’s d greater than 0.3) was found in six radioulnar contrasts on the right hand, all of which involved the radial ridge count of the 2nd finger. Of these, the highest average dimorphism was observed for the difference between the radial ridge count of the 2nd finger and the ulnar ridge count of the 4th finger (2r4u contrast), where the average effect size from all four population samples was comparable to a published average effect size of the 2D:4D finger length ratio. Conclusion We propose that 2r4u contrast of ridge counts could serve as a marker of prenatal sexual development targeting a temporally narrow developmental window.

A variety of models are available for the estimation of parameters of the human growth curve. Several have been widely and successfully used with longitudinal data that are reasonably complete. On the other hand, the modeling of data for a limited number of observation points is problematic and requires the interpolation of the interval between points and often an extrapolation of the growth trajectory beyond the range of empirical limits (prediction). This study tested a new approach for fitting a relatively limited number of longitudinal data using the normal variation of human empirical growth curves. First, functional principal components analysis was done for curve phase and amplitude using complete and dense data sets for a reference sample (Brno Growth Study). Subsequently, artificial curves were generated with a combination of 12 of the principal components and applied for fitting to the newly analyzed data with the Levenberg–Marquardt optimization algorithm. The approach was tested on seven 5-points/year longitudinal data samples of adolescents extracted from the reference sample. The samples differed in their distance from the mean age at peak velocity for the sample and were tested by a permutation leave-one-out approach. The results indicated the potential of this method for growth modeling as a user-friendly application for practical applications in pediatrics, auxology and youth sport.

Unzurrunzaga FM. 1976. Estudio de las líneas dermopapilares dactilares en mujeres vascas. Análisis de las diferencias sexuales y comparación de los vascos con poblaciones españolas y no españolas.

VyuŽiTÍ SociÁlnÍch SÍTÍ uniVerZiTnÍmi STudenTyABSTRAKT Internetové sociální sítě (Facebook, MySpace, LinkedIn, Twitter, …) se staly skutečně významným jevem mezilidské komunikace a mají výrazný vliv na to, jakým způsobem mezi sebou lidé udržují spojení. V současnosti užívají sociální sítě milióny mladých lidí. Mezi nejaktivnější uživatele patří mládež ve věku 13-19 let. Z recentních studií vyplývá, že mládež tráví značnou část dne interakcemi na sociálních médiích a je třeba hledat fundované odpovědi na palčivou otázku vlivu sociálních sítí na vývoj mladých lidí. Jen málo je známo o základních údajích -v jaké míře, proč a jak mládež tyto sítě využívá. V rámci této studie se 561 univerzitních studentů různých národností zúčastnilo průzkumu, který pomáhá osvětlit aktivity mladých lidí v těchto internetových komunitách. Naše zjištění naznačují, že aktivní působení na sociálních sítích je pro tuto novou generaci zcela typické a že Facebook je nejčastěji využíván k udržení kontaktu, udržení se ve středu dění. Dále byl zjištěn silný vztah mezi užíváním Facebooku a závislostí na udržení sociálního kapitálu. Emerging studies fi nd that youth spend a considerable amount of time in their daily life interacting through social media. Subsequently, questions and controversies emerge about the eff ects SNS have on adolescent development. Little is known about how much, why, and how they use these sites. In this study, 561 university students of diff erent nationalities completed a survey that helps clarify these questions that surround youth participation in these online communities. Our fi ndings suggest that social networks are the modus operandi of the new generation and that Facebook is mostly used to keep up to date. In addition, a strong connection was found between Facebook use and the addiction to maintaining social capital.

Objectives: Family represents the closest social environment that immediately affects human ontogeny from an early prenatal period. This study aimed to assess sibship influences on the second-to-fourth digit length ratio (2D:4D ratio). Methods: The source sample represented 329 children aged 6.5 to 15.8 years (Czech Republic), including a subsample of 75 sibling pairs. A combination of (a) betweenfamily design (cross-sectional sample) and (b) within-family design (pairs of siblings) was used to study the effect of family variables and interbirth interval (IBI) on the 2D:4D ratio. Results: Birth order, number of siblings (except for younger sisters), and sex ratio in siblings were significantly related to the 2D:4D ratio on the right, left, or both hands.At the same time, the relationships were opposite in males and females for birth order, number of older brothers and number of children in the family--increasing values in these variables increased digit ratio in males but decreased digit ratio in females. Mean difference in 2D:4D ratio (DIFF) within pairs (older minus younger sibling) differed from zero only in the "older sister--younger brother" group, where DIFF did not depend on IBI. On the contrary, in remaining pair types the DIFF tended to change with IBI, the strongest in the "older brother--younger sister" pairs. Conclusions: Family variables, especially number of older brothers, should be considered as important confounding factors in 2D:4D ratio studies. However, the effect of these variables might be modified by IBI.