scholarly journals A model of developmental canalization, applied to human cranial form

2021 ◽  
Vol 17 (2) ◽  
pp. e1008381
Author(s):  
Philipp Mitteroecker ◽  
Ekaterina Stansfield
Keyword(s):  
Compensatory Growth ◽  
Individual Development ◽  
Upper Airways ◽  
Cross Sectional ◽  
Geometric Morphometric ◽  
Individual Health ◽  
Cross Sectional Size ◽  
Frontal Sinuses ◽  
Organismal Development ◽  
Developmental Dynamics

Developmental mechanisms that canalize or compensate perturbations of organismal development (targeted or compensatory growth) are widely considered a prerequisite of individual health and the evolution of complex life, but little is known about the nature of these mechanisms. It is even unclear if and how a “target trajectory” of individual development is encoded in the organism’s genetic-developmental system or, instead, emerges as an epiphenomenon. Here we develop a statistical model of developmental canalization based on an extended autoregressive model. We show that under certain assumptions the strength of canalization and the amount of canalized variance in a population can be estimated, or at least approximated, from longitudinal phenotypic measurements, even if the target trajectories are unobserved. We extend this model to multivariate measures and discuss reifications of the ensuing parameter matrix. We apply these approaches to longitudinal geometric morphometric data on human postnatal craniofacial size and shape as well as to the size of the frontal sinuses. Craniofacial size showed strong developmental canalization during the first 5 years of life, leading to a 50% reduction of cross-sectional size variance, followed by a continual increase in variance during puberty. Frontal sinus size, by contrast, did not show any signs of canalization. Total variance of craniofacial shape decreased slightly until about 5 years of age and increased thereafter. However, different features of craniofacial shape showed very different developmental dynamics. Whereas the relative dimensions of the nasopharynx showed strong canalization and a reduction of variance throughout postnatal development, facial orientation continually increased in variance. Some of the signals of canalization may owe to independent variation in developmental timing of cranial components, but our results indicate evolved, partly mechanically induced mechanisms of canalization that ensure properly sized upper airways and facial dimensions.

scholarly journals A model of developmental canalization, applied to human cranial form

2020 ◽  
Author(s):  
Philipp Mitteroecker ◽  
Ekaterina Stansfield
Keyword(s):  
Statistical Model ◽  
Postnatal Development ◽  
Frontal Sinus ◽  
Individual Development ◽  
Craniofacial Morphology ◽  
Upper Airways ◽  
Individual Health ◽  
Developmental Mechanisms ◽  
Facial Orientation ◽  
Organismal Development

AbstractDevelopmental mechanisms that canalize or compensate perturbations of organismal development (targeted or compensatory growth) are widely considered a prerequisite of individual health and the evolution of complex life, but little is known about the nature of these mechanisms. It is even unclear if and how a “target trajectory” of individual development is encoded in the organism’s genetic-developmental system or, instead, emerges as an epiphenomenon. Here we develop a statistical model of developmental canalization based on an extended autoregressive model. We show that under certain assumptions the strength of canalization and the amount of canalized variance in a population can be estimated, or at least approximated, from longitudinal phenotypic measurements, even if the target trajectories are unobserved. We extend this model to multivariate measures and discuss reifications of the ensuing parameter matrix. We apply these approaches to longitudinal geometric morphometric data on human postnatal craniofacial size and shape as well as to the size of the frontal sinuses. Craniofacial size showed strong developmental canalization during the first 5 years of life, leading to a 50% reduction of cross-sectional size variance, followed by a continual increase in variance during puberty. Frontal sinus size, by contrast, did not show any signs of canalization. Total variance of craniofacial shape decreased slightly until about 5 years of age and increased thereafter. However, different feature of craniofacial shape showed very different developmental dynamics. Whereas the relative dimensions of the nasopharynx showed strong canalization and a reduction of variance throughout postnatal development, facial orientation continually increased in variance. Some of the signals of canalization may owe to independent variation in developmental timing of cranial components, but our results indicate evolved, partly mechanically induced mechanisms of canalization that ensure properly sized upper airways and facial dimensions.Author summaryDevelopmental mechanisms that canalize or compensate perturbations of organismal development are a prerequisite of individual health and the evolution of complex life. However, surprisingly little is known about these mechanisms, partly because the “target trajectories” of individual development cannot be observed directly. Here we develop a statistical model of developmental canalization that allows one to estimate the strength of canalization and the amount of canalized variance in a population even if the target trajectories are unobserved. We applied these approaches to data on human postnatal craniofacial morphology. Whereas overall craniofacial size was strongly canalized during the first 5 years of age, frontal sinus size did not show any signs of canalization. The relative dimensions of the nasopharynx showed strong canalization and a reduction of variance throughout postnatal development, while other shape features, such as facial orientation, continually increased in variance. Our results indicate evolved, partly mechanically induced mechanisms of canalization that ensure properly sized upper airways and facial dimensions.

scholarly journals Views on Aging and Well-Being in the Covid Crisis – A Longitudinal Study in Luxembourg

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 961-961
Author(s):  
Anna Kornadt ◽  
Martine Hoffmann ◽  
Elke Murdock ◽  
Josepha Nell ◽  
Isabelle Albert
Keyword(s):  
Older Adults ◽  
Well Being ◽  
Subjective Health ◽  
Community Dwelling ◽  
Individual Development ◽  
Subjective Age ◽  
Negative Effects ◽  
Cross Sectional ◽  
Social Loss ◽  
Physical Decline

Abstract During the Covid-Crisis, stereotypes of older adults as helpless and vulnerable were spread, and intergenerational conflict was stirred more or less openly. We thus focused on perceived ageism during the crisis and its effects on well-being and health of older adults. Since views on aging are multifaceted and can be both, risk and resource for individual development, we assessed people’s self-perceptions of aging (SPA) as social loss, continued growth and physical decline and subjective age (SA). We hypothesized that people with SPA of social loss and physical decline would be more susceptible to negative effects of perceived ageism, whereas those with SPA of continued growth and younger SA would be less affected. NT1 = 611 community-dwelling adults aged 60 – 98 (Mage = 69.92 years) were recruited in June 2020 online and via phone in Luxembourg. In September 2020, participants will be contacted again for a follow-up. Analyses with cross-sectional data show that participants who felt more discriminated reported lower life satisfaction after the onset of the crisis (r = -.35) and worse subjective health (r = -.14). SPA of social loss and higher SA increased the negative effect of ageism on well-being (beta = -.57) and subjective health (beta = -.53), respectively. Our results point to mid- and long-term consequences of age discriminatory and stereotype-based crisis communication for the well-being of older adults and the importance of individual SPA in critical situations.

Infrared Diagnostics of Free Charge Carriers in Silicon Nanowires

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940030 ◽  
Author(s):  
A. I. Efimova ◽  
E. A. Lipkova ◽  
K. A. Gonchar ◽  
A. A. Eliseev ◽  
V. Yu. Timoshenko
Keyword(s):  
Silicon Nanowires ◽  
Crystalline Silicon ◽  
Free Charge Carrier ◽  
Charge Carrier Concentration ◽  
Attenuated Total Reflection ◽  
Free Charge ◽  
Cross Sectional ◽  
Text Type ◽  
Cross Sectional Size ◽  
Potential Applications

Free charge carrier concentration in arrays of silicon nanowires (SiNWs) with cross-sectional size of the order of 100[Formula: see text]nm was quantitatively studied by means of the infrared spectroscopy in an attenuated total reflection mode. SiNWs were formed on lightly-doped [Formula: see text]-type crystalline silicon substrates by metal-assisted chemical etching followed by additional doping through thermoactivated diffusion of boron at 900–1000∘C. The latter process was found to increase the concentration of free holes in SiNWs up to [Formula: see text][Formula: see text]cm[Formula: see text]. Potential applications of highly doped SiNWs in thermoelectric energy converters and infrared plasmonic devices are discussed.

Structural Design of a Multifunctional Morphing Fowler Flap for a Twin-Prop Regional Aircraft

2018 ◽  
Author(s):  
Francesco Rea ◽  
Francesco Amoroso ◽  
Rosario Pecora ◽  
Maria Chiara Noviello ◽  
Maurizio Arena
Keyword(s):  
Finite Element ◽  
Analysis Tool ◽  
Load Path ◽  
Element Analysis ◽  
Cross Sectional ◽  
Aerodynamic Performances ◽  
Cross Sectional Size ◽  
Elementary Methods ◽  
Minimum Number ◽  
Mode 3

In the framework of Clean Sky 2 Airgreen 2 (REG-IADP) European research project, a novel multifunctional morphing flap technology was investigated to improve the aerodynamic performances of the next Turboprop regional aircraft (90 passengers) along its flight mission. The proposed true-scale device (5 meters span with a mean chord of 0.6 meters) is conceived to replace and enhance conventional Fowler flap with new functionalities. Three different functions were enabled: overall airfoil camber morphing up to +30° (mode 1), +10°/−10° (upwards/downwards) deflections of the flap tip segment (mode 2), flap tip “segmented” twist of ±5° along the outer flap span (mode 3). Morphing mode 1 is supposed to be activated during take-off and landing only to enhance aircraft high-lift performances and steeper initial climb and descent. Thanks to this function, more airfoil shapes are available at each flap setting and therefore a dramatic simplification of the flap deployment system may be implemented. Morphing modes 2 and 3 are enabled in cruise and off-design flight conditions to improve wing aerodynamic efficiency. The novel structural concept of the three-modal morphing Fowler flap (3MMF) was designed according to the challenges posed by real wing installation issues. The proposed concept consists of a multi-box arrangement activated by segmented ribs with embedded inner mechanisms to realize the transition from the baseline configuration to different target aero-shapes while withstanding the aerodynamic loads. Lightweight and compact actuating leverages driven by electromechanical motors were properly synthesized to comply with stringent requirements for real aircraft implementation: minimum actuating torque, minimum number of motors, reduced weight, and available design space. The methodology for the kinematic design of the inner mechanisms is based on a building block approach where the instant center analysis tool is used to preliminary select the locations of the hinges’ leverages. The final geometry of the inner mechanisms is optimized to maximize the mechanical advantage as well as to provide the kinematic performances required by the three different morphing modes. The load-path was evaluated, and the cross-sectional size of leverages was subsequently optimized. Finally, actuating torques predicted by instant center analysis were compared to the calculated values from finite element analysis. The structural sizing process of the multi-box arrangement was carried out considering elementary methods, and results were compared with finite element simulations.

scholarly journals A cross-sectional study of the use and effectiveness of the Individual Development Plan among doctoral students

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 722 ◽  
Author(s):  
Nathan L. Vanderford ◽  
Teresa M. Evans ◽  
L. Todd Weiss ◽  
Lindsay Bira ◽  
Jazmin Beltran-Gastelum
Keyword(s):  
Career Development ◽  
Doctoral Students ◽  
Online Survey ◽  
Career Planning ◽  
Statistical Significance ◽  
Development Plan ◽  
Individual Development ◽  
Negative Consequences ◽  
Cross Sectional ◽  
The Individual

Background: The Individual Development Plan (IDP) was introduced as a tool to aid in career planning for doctoral trainees. Despite the National Institutes of Health and academic institutions creating policies that mandate the use of IDPs, little information exists regarding the use and effectiveness of the career planning tool. Methods: We conducted a multi-institutional, online survey to measure IDP use and effectiveness. The survey was distributed to potential respondents via social media and direct email. IDP survey questions were formatted using a five-point Likert scale (strongly agree, agree, neutral, disagree and strongly disagree). For data analysis purposes, responses were grouped into two categories (agree versus does not agree/disagree). The data were summarized as one-way frequencies and the Pearson chi-square test was used to determine the statistical significance of univariate associations between the survey variables and an outcome measure of the effectiveness of the IDP. Results: Among all respondents, fifty-three percent reported that they are required to complete an IDP while thirty-three percent reported that the tool is helpful to their career development. Further, our data suggests that the IDP is most effective when doctoral students complete the tool with faculty mentors with whom they have a positive relationship. Respondents who are confident about their career plans and who take advantage of career development resources at their institution are also more likely to perceive that the IDP is useful for their career development. Conclusion: Given the nuanced use and effectiveness of the IDP, we call for additional research to characterize the overall use and effectiveness of the IDP and to determine whether there are unintended negative consequences created through the use of the tool. Furthermore, we recommend an enhancement of career development infrastructure that would include mentorship training for faculty in order to provide substantially more career planning support to trainees.

Modeling growth stocks via birth-death processes

2003 ◽  
Vol 35 (3) ◽  
pp. 641-664 ◽  
Author(s):  
S. C. Kou ◽  
S. G. Kou
Keyword(s):  
Size Distribution ◽  
Death Process ◽  
Cross Sectional ◽  
Share Prices ◽  
Cross Sectional Size ◽  
High Volatility ◽  
Growth Stocks ◽  
Future Growth ◽  
Modeling Growth ◽  
Birth Death

The inability to predict the future growth rates and earnings of growth stocks (such as biotechnology and internet stocks) leads to the high volatility of share prices and difficulty in applying the traditional valuation methods. This paper attempts to demonstrate that the high volatility of share prices can nevertheless be used in building a model that leads to a particular cross-sectional size distribution. The model focuses on both transient and steady-state behavior of the market capitalization of the stock, which in turn is modeled as a birth-death process. Numerical illustrations of the cross-sectional size distribution are also presented.

Study on Fatigue Properties of Double-Wall-Brazed-Tube

2011 ◽  
Vol 105-107 ◽  
pp. 1644-1647
Author(s):  
Qi Rong Zhu ◽  
Ming Ru Xie ◽  
Xiao Hua Li
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Shaking Table ◽  
Fatigue Properties ◽  
Metal Fatigue ◽  
Cross Sectional ◽  
Data Analysis Procedure ◽  
Cross Sectional Size ◽  
Double Wall

This paper is referred to other literature on properties of metal fatigue testing methods and data analysis procedure methods. According to high cycle fatigue testing, double-wall-brazed-tube is loaded with different stimulated vibration force by shaking table and is forced to vibrate. In the experience, strain of key parts is measured with Electrical resistance Strain measurement Methods. By curve fitting of experimental data, we gain the fitting function of the specimen’s fatigue life and draw its S-N curve. In accordance with the analysis of experimental data and S-N curves, it is concluded that fatigue properties of metallic materials can not fully reflect fatigue properties of a specimen and that the cross-sectional size of a specimen has much effects on its fatigue life.

Morphologic Changes in the Upper Airway of Children during Awakening from Propofol Administration

2002 ◽  
Vol 96 (3) ◽  
pp. 607-611 ◽  
Author(s):  
Ronald S. Litman ◽  
Eric E. Weissend ◽  
David A. Shrier ◽  
Denham S. Ward
Keyword(s):  
Soft Palate ◽  
Upper Airway ◽  
Cross Sectional Area ◽  
Transverse Diameter ◽  
Sectional Area ◽  
Upper Airways ◽  
Cross Sectional ◽  
Propofol Sedation ◽  
The Cross ◽  
Morphologic Changes

Background The purpose of this study was to determine the morphologic changes that occur in the upper airway of children during awakening from propofol sedation. Methods Children undergoing magnetic resonance imaging of the head underwent additional scans of the upper airway during deep sedation with propofol; this was repeated on awakening. Axial views were obtained at the most posterior sites of the pharynx at the levels of the soft palate and tongue. Measurements were then obtained of the anterior-posterior (A-P) diameter, transverse diameter, and cross-sectional areas at these levels. Results Data were obtained on 16 children, aged 10 months to 7 yr. In both sedated and awakening states, most children had the smallest cross-sectional area of the pharynx at the level of the soft palate. During the sedated state, at the soft palate level, the transverse diameter was most narrow in 11 children, the A-P diameter was most narrow in 1 child, and they were equal in 2 children. During the sedated state, at the level of the tongue, the transverse diameter was most narrow in 9 children, the A-P diameter was most narrow in 5 children, and they were equal in 2 children. During awakening, at the soft palate level, the transverse diameter was most narrow in none of the children, the A-P diameter was most narrow in 13 children, and they were equal in 1 child. At the level of the tongue, the transverse diameter was most narrow in 4 children, and the A-P diameter was most narrow in 12 children. During awakening, the A-P diameter of the pharynx at the level of the soft palate decreased in 12 children, increased in 1 child, and remained the same in 1 child. (P < 0.001). The transverse diameter increased in 11 children, decreased in 1 child, and remained the same in 2 children (P = 0.001). The cross-sectional area at the level of the soft palate increased in 4 children, decreased in 8 children, and stayed the same in 2 children (P = 0.5). During awakening, the A-P diameter of the pharynx at the level of the tongue decreased in 11 children, increased in 4 children, and remained the same in 1 child. (P = 0.01). The transverse diameter increased in 11 children and decreased in 5 children (P = 0.07). The cross-sectional area at the level of the tongue increased in 7 children, decreased in 7 children, and stayed the same in 2 children (P = 0.9). Conclusions The dimensions of the upper airways of children change shape significantly on awakening from propofol sedation. When sedated, the upper airway is oblong shaped, with the A-P diameter larger than the transverse diameter. On awakening, the shape of the upper airway in most children changed such that the transverse diameter was larger. Cross-sectional areas between sedated and awakening states were unchanged. These changes may reflect the differential effects of propofol on upper airway musculature during awakening.

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