Virtual fit and design improvements of a filtering half-mask for sub-adult wearers.

The recent pandemic has shown that protecting the general population from hazardous substances or pathogens can be a challenging and urgent task. The key element to adequate protection is appropriately sized, well-fitted and sufficiently distributed personal protective equipment (PPE). While these conditions are followed for adult PPE wearers, they are less considered when it comes to protecting subadults. In this study, the assessment of the fit and design improvements of a 3D-printed facial half mask for subadult wearers (4-18 years) is designed. The target population was represented by 1137 subadults, aged 4.06-18.94 years, for whom 3D face models were acquired. The half mask tested, which was originally provided in one subadult size, did not fit appropriately the target population. This finding prompted the creation of four size categories using the age-dependent distribution of the centroid size calculated from 7 facial landmarks. For each size category, a modified half-mask virtual design was created, including resizing and reshaping, and fit was evaluated visually and numerically using averaged and random 3D face representatives.Practitioner summary: The reason for this study was to describe procedures which led to design improvement of an existing half-mask and provide respiratory protection for subadults. To address this, fit was assessed using an innovative metric approach. Four sizes were then created based on centroid size, resulting in improved fit and design.Abbreviations: CH: cheilion landmark; CS: centroid size; EX: exocanthion landmark; GN: gnathion landmark; N: nasion landmark; PPE: personal protective equipment; PR: pronasale landmark; RPE: respiratory protective equipment.

3D human face dataset was used for modifying and validating protective equipment for subadultsTo ensure optimal protection for subadults, four size categories were proposed based on 3D face landmarks and centroid sizeModified half-mask design fit was validated virtually using a visual and numerical approach.

Within-family intergenerational trends in age at menarche relative to political changes in Czechoslovakia after World War II.

OBJECTIVES: The aim of the study was to examine a secular trend in age at menarche (AAM) in the former Czechoslovak (and descendant Slovak and Czech) population in relation to its large-scale political and social events taking place after World War II. METHODS: The study included 211 women aged 18-30 (born during 1984-1998), and their relatives: mothers, sisters, and grandmothers, yielding a total of 421 women. Changes in retrospectively recalled AAM between the three generations of women (oldest-grandmothers, middle-mothers, and youngest-daughters) were studied in pairwise comparisons. Relationships between AAM and the birth/conception date were analyzed relative to three events in the post-WWII Czechoslovakia (1948, 1968, and 1989). RESULTS: AAM was the highest in the oldest generation, slightly lower in the middle generation and the lowest in the youngest generation. Mixed-Effect Model showed statistically significant interaction between the date of conception, historical events, and the period before and after the event. CONCLUSIONS: The recorded decline in AAM is congruent with secular trends reported in the literature. However, the decreasing trend was not linear and included an increase in AAM in women conceived within the five-year period after the invasion of Czechoslovakia by communist armies in 1968.

Radioulnar contrasts in fingerprint ridge counts: Searching for dermatoglyphic markers of early sex development.

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.

Estimating Growth in Height from Limited Longitudinal Growth Data Using Full-Curves Training Dataset: A Comparison of Two Procedures of Curve Optimization-Functional Principal Component Analysis and SITAR.

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.

Normal-weight obesity frequency in the Central European urban adult female population of Brno, Czech Republic.

OBJECTIVES: The universally recognized indicator of nutritional status, BMI, has some shortcomings, especially in detecting overweight and obesity. A relatively recently introduced normal weight obesity (NWO) describes a phenomenon when individuals are found to have normal weight as indicated by BMI but have an elevated percentage of body fat. Normal weight obese individuals face a higher risk of developing metabolic syndrome, cardiometabolic dysfunction and have higher mortality. No studies have been previously performed which would map NWO in Brno, Czech Republic. METHODS: In a sample of 100 women from Brno, we assessed the percentage of normal weight obese individuals using bioelectric impedance analysis (BIA) - three different analyzers were utilized: Tanita BC-545 personal digital scale, InBody 230 and BodyStat 1500MDD. Also, a caliperation method was used to estimate body fat percentage. Various body fat percentage cut-off points were used according to different authors. RESULTS: When the 30% body fat (BF) cut-off was used, up to 14% of the women in our sample were found to be normal weight obese. When the sum of skinfolds or the 35% BF cut-off point are selected as a criterion for identifying normal weight obesity (NOW), only 1 of 100 examined women was identified as normal weight obese; at the 35% BF cut-off, BodyStat analyzer categorized no women as normal weight obese. Also, when the 30% BF or 66th percentile BF cut-off points were utilized, BodyStat identified pronouncedly fewer women from our sample to be normal-weight obese than the two other analyzers. CONCLUSIONS: On a pilot sample of Czech women, we demonstrated that depending on the selected cut-off (there is no clear agreement on cut-off points in literature), up to 14% of the examined women were found to be normal weight obese.

Family effects on the digit ratio (2D:4D): The role of the interbirth interval.

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) between-family 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.

Sex differences in frequencies of dermatoglyphic patterns by individual fingers.

Background: The size of sex differences in dermatoglyphic features and their inter-population differences remains a subject of debate. Combining fingers in traditional dermatoglyphic methodology and omitting finger-specific variations might be a cause for uncertainty.Aim: To compare sex differences in whorl frequencies between fingers.Subjects and methods: Using meta-analytical methods, the authors studied sex differences in frequencies of whorls (log Odd Ratios) for each finger separately, including their heterogeneities (between-samples variance). The dataset of 204 population samples was extracted from published dermatoglyphic studies.Results: Aggregated effects of sex differences were significant in all fingers, except for the left 1st finger. Sex differences were higher in the right hand and increased from radial to ulnar fingers. Apart from the right 1st and 3rd fingers, heterogeneities were small and literally zero in the right 4th finger.Conclusion: Higher sex differences in ulnar fingers and the lack of interpopulation differences all over the world in the 4th finger might be caused by a stronger influence of genetic and/or hormonal factors on dermatoglyphic development of the ulnar side of the hand. It is suggested that future studies, when applying dermatoglyphic traits as markers of prenatal environment, use traits by individual fingers or their relationships within the hand.