Population Asymmetry Research Articles

Carpal variability and asymmetry in limb reduced Western lesser sirens (Siren nettingi).

Trait functionality can act as a constraint on morphological development. Traits that become vestigialized can exhibit unstable developmental patterns such as fluctuating asymmetry (FA) and variation in populations. We use clearing and staining along with morphometric analyzes to compare FA and allometry of limbs in Western lesser sirens (Siren nettingi) to Ouachita dusky salamanders (Desmognathus brimleyorum). Our results describe new carpal phenotypes and carpal asymmetry in our sample of S. nettingi. However, we found no significant evidence of limb length asymmetry in S. nettingi. The degree of relative limb asymmetry correlates inversely with body size in both of our samples. This work provides strong evidence of increased mesopodal variation within a population of S. nettingi. Our work provides a basis for further study of a broader range of morphological traits across salamanders.

Complex pathways to cooperation emergent from asymmetry in heterogeneous populations.

Cooperation within asymmetric populations has garnered significant attention in evolutionary games. This paper explores cooperation evolution in populations with weak and strong players, using a game model where players choose between cooperation and defection. Asymmetry stems from different benefits for strong and weak cooperators, with their benefit ratio indicating the degree of asymmetry. Varied rankings of parameters including the asymmetry degree, cooperation costs, and benefits brought by weak players give rise to scenarios including the prisoner's dilemma (PDG) for both player types, the snowdrift game (SDG), and mixed PDG-SDG interactions. Our results indicate that in an infinite well-mixed population, defection remains the dominant strategy when strong players engage in the prisoner's dilemma game. However, if strong players play snowdrift games, global cooperation increases with the proportion of strong players. In this scenario, strong cooperators can prevail over strong defectors when the proportion of strong players is low, but the prevalence of cooperation among strong players decreases as their proportion increases. In contrast, within a square lattice, the optimum global cooperation emerges at intermediate proportions of strong players with moderate degrees of asymmetry. Additionally, weak players protect cooperative clusters from exploitation by strong defectors. This study highlights the complex dynamics of cooperation in asymmetric interactions, contributing to the theory of cooperation in asymmetric games.

Sex differences in workload in medieval Poland: Patterns of asymmetry and biomechanical adaptation in the upper limb at Giecz.

This study characterizes sexual dimorphism in skeletal markers of upper limb mechanical loading due to lateralization as evidence of division of labor in medieval Giecz, Poland. Twenty-six dimensions for paired humeri, clavicles, and radii representing adult males (n = 89) and females (n = 53) were collected from a skeletal sample from the cemetery site Gz4. Percent directional asymmetry (DA) and absolute asymmetry (AA) for each dimension were compared among bones, osteometric subcategories, and sex. Additionally, side bias and sex differences were assessed in degenerative joint disease (DJD) and entheseal changes (ECs). Nearly all measurements revealed significant asymmetry favoring the right side. Asymmetry was most pronounced in midshaft dimensions with few sex differences. There were more correlations among dimensions within elements than between elements, mainly in the midshaft. No laterality in DJD frequencies was noted for either sex, but females demonstrated significantly lower odds of having DJD than males in most joints. Most ECs demonstrated a right-bias and association with DA with no sex-specific patterns except the biceps brachii insertion, where females were ~5 times more likely to be scored "right" than males. The general lack of sex differences in asymmetry and ECs suggests similarly demanding workloads for females and males, with the exception of sex-specific functional loading differences in the forearm. Further, DJD data suggest males engaged in more intensive activities involving the upper limb. These results enhance understanding of workload in this important historical period and provide a comparison for asymmetry in past populations.

Cranial fluctuating asymmetry in Danish populations from the Neolithic to the Early Modern Age

Fluctuating asymmetry are random deviations of an otherwise symmetrical body plan and arises from instability in development. Earlier studies suggest that levels of cranial fluctuating asymmetry may be influenced by lifestyle and quality of life in a population. It may, therefore, be useful as a stress indicator. We investigated whether cranial fluctuating asymmetry has changed in archaeological Danish populations over time, and between grave sites from the same time period. Our sample consisted of 219 adult individuals from the Neolithic Age (approx. 3000BC) to the Early Modern Age (approx. 1850). We collected 27 3-dimensional landmarks from the face, calvarium, and base of the cranium. Levels of shape variation were analyzed using Procrustes analysis of variance and principal component analysis. Cemeteries, time periods, and sex were compared using linear mixed models, one-way analysis of variance, and Kruskal-Wallis test. We found no statistically significant differences in cranial FA between grave sites from the same time period, nor did we find any statistically significant difference between time periods. We found that sex did not have an influence on levels of cranial FA. We found no measurable difference in levels of cranial FA between Danish populations over time. Further knowledge on genetics and other stress indicators in our sample may give more insight into the relationship between cranial fluctuating asymmetry and developmental instability.

Neurodiversity in Brain Organisation

IN A HIGHLY engaging session during the European Academy of Neurology (EAN) Congress 2023, discussing neurodiversity in brain organisation, Annakarina Mundorf, Medical School Hamburg, Germany, spoke about the role of laterality in neurological diseases, while Sebastian Ocklenburg, Medical School Hamburg, Germany, discussed asymmetries in clinical and non-clinical populations.

Single-cell expression profile of Drosophila ovarian follicle stem cells illuminates spatial differentiation in the germarium

BackgroundHow stem cell populations are organized and regulated within adult tissues is important for understanding cancer origins and for developing cell replacement strategies. Paradigms such as mammalian gut stem cells and Drosophila ovarian follicle stem cells (FSC) are characterized by population asymmetry, in which stem cell division and differentiation are separately regulated processes. These stem cells behave stochastically regarding their contributions to derivative cells and also exhibit dynamic spatial heterogeneity. Drosophila FSCs provide an excellent model for understanding how a community of active stem cells maintained by population asymmetry is regulated. Here, we use single-cell RNA sequencing to profile the gene expression patterns of FSCs and their immediate derivatives to investigate heterogeneity within the stem cell population and changes associated with differentiation.ResultsWe describe single-cell RNA sequencing studies of a pre-sorted population of cells that include FSCs and the neighboring cell types, escort cells (ECs) and follicle cells (FCs), which they support. Cell-type assignment relies on anterior–posterior (AP) location within the germarium. We clarify the previously determined location of FSCs and use spatially targeted lineage studies as further confirmation. The scRNA profiles among four clusters are consistent with an AP progression from anterior ECs through posterior ECs and then FSCs, to early FCs. The relative proportion of EC and FSC clusters are in good agreement with the prevalence of those cell types in a germarium. Several genes with graded profiles from ECs to FCs are highlighted as candidate effectors of the inverse gradients of the two principal signaling pathways, Wnt and JAK-STAT, that guide FSC differentiation and division.ConclusionsOur data establishes an important resource of scRNA-seq profiles for FSCs and their immediate derivatives that is based on precise spatial location and functionally established stem cell identity, and facilitates future genetic investigation of regulatory interactions guiding FSC behavior.

Asymmetric shoe height induces reactive changes in gait kinematics but not kinetics in healthy young adults

BackgroundFootwear interventions are a potential avenue to correct walking asymmetry in neurologic populations, such as stroke. However, the motor learning mechanisms that underlie the changes in walking imposed by asymmetric footwear are unclear. Research questionThe objectives of this study were to examine symmetry changes during and after an asymmetric shoe height intervention in (1) vertical impulse and (2) spatiotemporal gait parameters and (3) joint kinematics, in healthy young adults MethodsEleven healthy young adults (3 males, 8 females; 21.2 ± 3.1 years old) participated in this study. Participants walked on an instrumented treadmill at 1.3 m/s for four conditions: (1) a 5-minute familiarization with equal shoe height, (2) a 5-minute baseline with equal shoe height, (3) a 10-minute intervention, where participants walked with asymmetric shoe height with a 10 mm shoe insert in one shoe, and (4) a 10-minute post-intervention, where participants walked with equal shoe height. Asymmetry in kinetics and kinematics were used to identify changes during intervention and aftereffects, a hallmark of feedforward adaptation ResultsParticipants did not alter vertical impulse asymmetry (p = 0.667) nor stance time asymmetry (p = 0.228). During the intervention, step time asymmetry (p = 0.003) and double support asymmetry (p < 0.001) were greater compared to baseline. Leg joint asymmetry during stance (Ankle plantarflexion: p < 0.001; Knee flexion: p < 0.001; Hip extension: p = 0.011) was greater during the intervention compared to baseline. However, changes in spatiotemporal gait variables and joint mechanics did not demonstrate aftereffects. SignificanceOur results show that healthy human adults change gait kinematics, but not weight-bearing symmetry with asymmetrical footwear. This suggests that healthy humans prioritize maintaining vertical impulse by changing their kinematics. Further, the changes in gait kinematics are short-lived, suggesting feedback-based control, and a lack of feedforward motor adaptations

Descriptors of dimensionality for n × n density matrices

By using the recently introduced parametrization of an n-dimensional density matrix in terms of the indices of population asymmetry and the intrinsic coherences, we define descriptors in both integer and continuous forms of the effective dimension that take place for a complete description of a density matrix, thus providing accurate information beyond the rank of the density matrix. The concepts of dimensional folding, hidden dimensional purity, and dimensional entropy are introduced and discussed in view of the new approach presented. The results are applicable to any physical system represented by a density matrix, such as n-level quantum systems, qutrits, sets of interacting pencils of radiation, classical polarization states, and to transformations of density matrices, as occurs with quantum channels.

Coherent control of symmetry breaking in transverse-field Ising chains using few-cycle pulses

Abstract Coherent control of quantum systems with phase-stable pulses offers enticing new opportunities for lightwave electronics. Here we extend this approach to many-body systems with spin degrees of freedom, demonstrating that a single few-cycle control pulse can create a sizable population asymmetry between the two degenerate polar ground states of the Ising model. This opens a route for femtosecond-scale data processing and storage, allowing one to control the final ground state of a correlated system in an all-optical way.

Euro-Med Abandoned Small(er) Towns. A landscape/ecological urbanism perspective for sustainable regeneration in Basilicata inlands

Inside a Mediterranean scenario of population asymmetries, this paper talks about and ongoing research that aims to highlight issues, identify a working method and tools able to support sustainable regenerative design strategies for abandoned historical small(er) towns and their landscapes, especially in inlands contexts. With these objectives, the research chooses Basilicata region, in the South of Italy, as emblematic for its structural marginality- morphological, infrastructural, social and economic -, bio-cultural diverse and diffused heritage and its seemingly unreversible depopulation process. Aging, low birth rates and high level of emigration has produced the abandonment of small(er) towns, of rural areas and, by the contrary, an increasing wilderness, changing the millennial settlement structure and impacting on socio-ecological resilience. Inside the theoretical framework of landscape/ecological urbanism and related design- oriented experimentations, the constellation of abandoned small(er) towns are interpreted as urban densities of a performative bio-cultural green infrastructure that could support, through design, the contemporary challenge of sustainable development, with a relational and glocal approach. Small(er) towns regeneration is view inside a more complex, interdisciplinary and holistic frame in which inter-scalarity, flux, dynamic and time variability are crucial. Performative bio-cultural green infrastructure, through the multiplication of public space, could support sustainable processes, in an ecological, economic and social sense. From an applicational point of view, the research intends to build a dynamic atlas for the regeneration of abandoned small(er) towns; the atlas is conceived both as a reading and a design tool able to support polyphonic and open process of sustainable regeneration.

Modeling of Water Quality in West Ukrainian Rivers Based on Fluctuating Asymmetry of the Fish Population

Increased concentrations of chemicals in surface waters affect the development of fish and the state of water bodies in general. In turn, the human consumption of fish that have accumulated heavy metals can cause toxicological hazards and endanger health. The importance of this area and the lack of water quality assessment methods in Ukraine based on the fluctuating asymmetry level of fish and the chemical parameters of water informed the object and aim of the current research. The object of this study was the use of fish populations as a bioindicator of water quality. The study had three purposes: (1) the determination of the dominant fish species and a comparison of their fluctuating asymmetry in the studied rivers; (2) the evaluation of the sensitivity/tolerance of the selected fish populations for assessing water quality; and (3) the creation of a model for assessing the water quality of the studied rivers based on the determined fluctuating asymmetry of the typical fish populations. Each of the studied fish populations had different frequency of fluctuating asymmetry (FFA) levels: the common roach had the highest value, and the silver crucian carp had the lowest. The final stage of the study was building an artificial neural network (ANN) model for predicting water quality based on the FFA of meristic features. Optimal results were obtained for the ANN model with the ReLU activation function and SGD optimization algorithm (MAPE = 6.7%; R2 = 0.97187). Such values for the MAPE and R2 indicators demonstrated that the level of agreement between the target and forecast data was satisfactory. The novelty of this research lay in the development of a model for assessing water quality based on the comparison of the fluctuating asymmetry values of the typical fish populations in the studied rivers.

Handgrip Strength Asymmetry Is Associated With Future Accumulating Morbidities In Older Americans

Functional asymmetries are an often-observed form of poor muscle function during aging that is typically not evaluated in handgrip strength (HGS) protocols. Examining such asymmetries in older populations may help in identifying persons at risk for future morbidities linked to poor muscle function. PURPOSE: We sought to determine the association between asymmetric HGS and future accumulating morbidities in older Americans. METHODS: The analytic sample included 18,506 participants aged 65.0 ± 10.2 years from the 2006-2016 waves of the Health and Retirement Study. HGS was collected on each hand with a handgrip dynamometer. The highest HGS on each hand was used for determining HGS asymmetry ratio: (non-dominant HGS/dominant HGS). Persons with HGS asymmetry ratio < 1.0 had their ratio inverted to make all ratios ≥1.0. Participants were categorized into asymmetry groups based on their inverted HGS asymmetry ratio: 1) 0.0%-10.0%, 2) 10.1%-20.0%, 3) 20.1%-30.0%, and 4) >30.0%. Each person reported the presence of healthcare provider diagnosed morbidities: hypertension, diabetes, cancer, chronic lung disease, cardiovascular disease, stroke, psychiatric problems, and arthritis. Separate covariate-adjusted ordinal generalized estimating equations were used for the analyses. RESULTS: Every 0.10 (i.e., 10%) increase in HGS asymmetry ratio was associated with 1.21 (95% confidence interval (CI): 1.09-1.35) greater odds for future accumulating morbidities. Compared to those with HGS asymmetry 0.0%-10.0%, persons with wider asymmetry had greater odds for future accumulating morbidities: 1.07 (CI: 1.02-1.12) for HGS asymmetry 10.1%-20.0%, 1.09 (CI: 1.02-1.16) for HGS asymmetry at 20.1%-30.0%, and 1.22 (CI: 1.11-1.35) for HGS asymmetry >30.0%. CONCLUSIONS: Functional asymmetries between limbs, as another form of muscle dysfunction, are associated with future morbidity accumulation in during aging. Moreover, wider strength asymmetries between limbs may especially elevate risk for future morbidity accumulation. We recommend that health practitioners evaluate HGS asymmetry as a simple screening mode for helping to determine poor muscle function and future morbidity risk.

Fluctuating Asymmetry in the head shape and parotid gland secretion in introduced cane toads (Rhinella marina) from established populations in Caraga State University, Butuan City, Agusan del Norte, Philippines

The study was supervised to determine and assess the ecological health of Caraga State University in Ampayon, Butuan City by looking into the level of fluctuating asymmetry in populations and affected landmarks of Rhinella marina. Various studies have shown that fluctuating asymmetry can be used to indirectly assess water quality as well as the overall health of the ecosystem. In this study, R. marina was utilized because of its abundance in Caraga State University. Hence, with the presence and use of the thin-plate spline (TPS) series, landmark analysis was obtained and subjected to Symmetry and Asymmetry in Geometric Data (SAGE) software. Wherein, the findings in Procrustes ANOVA showed that although individual symmetry delineate no significant difference, Sides (Directional Asymmetry) and Interaction (Fluctuating asymmetry) showed a highly significant difference (P = 0.0000***). Furthermore, the results of Principal Component Scores display a high percentage Fluctuating Asymmetry of pooled (79.964%). Thus, in the results, PC 1 (40.589%), PC2 (18.8634%), PC3 (12.7566%), and PC4 (7.755%), the interaction was explicitly found to have significant variations affecting the R. marina parotid gland, landmarks of the loreal crest, and supra-tympanic edge of the cane toad. A significant proportion of the variation in head shape can be explained by environmental variables, suggesting that conditions of the physical environment should also be considered as a source of morphological variation. To conclude, this study authenticated the use of fluctuating asymmetry in determining and assessing the status of the ecological health of the study area confirming that indeed results of high FA equates for the incidence of cane toads in the area.

A Systematic Review of Non-Pharmacological Interventions to Improve Gait Asymmetries in Neurological Populations

Gait asymmetries are commonly observed in neurological populations and linked to decreased gait velocity, balance decrements, increased fall risk, and heightened metabolic cost. Interventions designed to improve gait asymmetries have varying methods and results. The purpose of this systematic review was to investigate non-pharmacological interventions to improve gait asymmetries in neurological populations. Keyword searches were conducted using PubMed, CINAHL, and Academic Search Complete. The search yielded 14 studies for inclusion. Gait was assessed using 3D motion capture systems (n = 7), pressure-sensitive mats (e.g., GAITRite; n = 5), and positional sensors (n = 2). The gait variables most commonly analyzed for asymmetry were step length (n = 11), stance time (n = 9), and swing time (n = 5). Interventions to improve gait asymmetries predominantly used gait training techniques via a split-belt treadmill (n = 6), followed by insoles/orthoses (n = 3). The literature suggests that a wide range of methods can be used to improve spatiotemporal asymmetries. However, future research should further examine kinematic and kinetic gait asymmetries. Additionally, researchers should explore the necessary frequency and duration of various intervention strategies to achieve the greatest improvement in gait asymmetries, and to determine the best symmetry equation for quantifying gait asymmetries.

Reduced joint motion supersedes asymmetry in explaining increased metabolic demand during walking with mechanical restriction

Recent research has highlighted the complex interactions among chronic injury- or disease-induced joint limitations, walking asymmetry, and increased metabolic cost. Determining the specific metabolic impacts of asymmetry or joint impairment in clinical populations is difficult because of concurrent neurological and physiological changes. This work investigates the metabolic impact of gait asymmetry and joint restriction by unilaterally (asymmetric) and bilaterally (symmetric) restricting ankle, knee, and combined ankle and knee ranges of motion in unimpaired individuals. We calculated propulsive asymmetry, temporal asymmetry, and step-length asymmetry for an average gait cycle; metabolic rate; average positive center of mass power using the individual limbs method; and muscle effort using lower limb electromyography measurements weighted by corresponding physiological cross-sectional areas. Unilateral restriction caused propulsive and temporal asymmetry but less metabolically expensive gait than bilateral restriction. Changes in asymmetry did not correlate with changes in metabolic cost. Interestingly, bilateral restriction increased average positive center of mass power compared to unilateral restriction. Further, increased average positive center of mass power correlated with increased energy costs, suggesting asymmetric step-to-step transitions did not drive metabolic changes. The number of restricted joints reduces available degrees of freedom and may have a larger metabolic impact than gait asymmetry, as this correlated significantly with increases in metabolic rate for 7/9 participants. These results emphasize symmetry is not by definition metabolically optimal, indicate that the mechanics underlying symmetry are meaningful, and suggest that available degrees of freedom should be considered in designing future interventions.

Plantar load transfer in children: a descriptive study with two pathological case studies

BackgroundTypical gait is often considered to be highly symmetrical, with gait asymmetries typically associated with pathological gait. Whilst gait symmetry is often expressed in symmetry ratios, measures of symmetry do not provide insight into how these asymmetries affect gait variables. To fully understand changes caused by gait asymmetry, we must first develop a normative database for comparison. Therefore, the aim of this study was to describe normative reference values of regional plantar load and present comparisons with two pathological case studies.MethodsA descriptive study of the load transfer of plantar pressures in typically developed children was conducted to develop a baseline for comparison of the effects of gait asymmetry in paediatric clinical populations. Plantar load and 3D kinematic data was collected for 17 typically developed participants with a mean age of 9.4 ± 4.0 years. Two case studies were also included; a 10-year-old male with clubfoot and an 8-year-old female with a flatfoot deformity. Data was analysed using a kinematics-pressure integration technique for anatomical masking into 5 regions of interest; medial and lateral forefoot, midfoot, and medial and lateral hindfoot.ResultsClear differences between the two case studies and the typical dataset were seen for the load transfer phase of gait. For case study one, lateral bias was seen in the forefoot of the trailing foot across all variables, as well as increases in contact area, force and mean pressure in the lateral hindfoot of the leading foot. For case study two, the forefoot of the trailing foot produced results very similar to the typical dataset across all variables. In the hindfoot of the leading foot, medial bias presents most notably in the force and mean pressure graphs.ConclusionsThis study highlights the clinical significance of the load transfer phase of gait, providing meaningful information for intervention planning.

Dynamic spatiotemporal coordination of neural stem cell fate decisions occurs through local feedback in the adult vertebrate brain.

SummaryNeural stem cell (NSC) populations persist in the adult vertebrate brain over a lifetime, and their homeostasis is controlled at the population level through unknown mechanisms. Here, we combine dynamic imaging of entire NSC populations in their in vivo niche over several weeks with pharmacological manipulations, mathematical modeling, and spatial statistics and demonstrate that NSCs use spatiotemporally resolved local feedback signals to coordinate their decision to divide in adult zebrafish brains. These involve Notch-mediated short-range inhibition from transient neural progenitors and a dispersion effect from the dividing NSCs themselves exerted with a delay of 9–12 days. Simulations from a stochastic NSC lattice model capturing these interactions demonstrate that these signals are linked by lineage progression and control the spatiotemporal distribution of output neurons. These results highlight how local and temporally delayed interactions occurring between brain germinal cells generate self-propagating dynamics that maintain NSC population homeostasis and coordinate specific spatiotemporal correlations.

About the asymmetry structure of the leaf blade Common plantain

Using the method of geometric morphometrics the contour of the image of the leaf blade of the Common plantain (Plantago major) was aligned along the axis of symmetry to answer the question of whether the asymmetry and shape were influenced by environmental pollution by vehicles and climatic conditions. Procrustes distances showed that fluctuating asymmetry was higher in roadside populations in 2019. In the control populations, a mixture of two types of asymmetry, fluctuating and directional, was obtained. In 2020 with high precipitation (47% more than in 2019), asymmetry was represented by higher directional asymmetry (p &lt;0.0001), although the overall asymmetry remained the same. The nonparametric Kruskal-Wallis test showed the influence on the shape only climatic environments of the year (p &lt;0.001). The geographical location of the populations and the combined effect of the factors year and the place of leaves gathering did not affect the shape of the leaf blade. In 2020, no data were obtained on the excess of asymmetry in roadside populations compared to the control, therefore authors conclude about the weak bioindicative properties of the Common plantain in response to traffic pollution.

Neural stem cell pools in the vertebrate adult brain: Homeostasis from cell-autonomous decisions or community rules?

Adult stem cell populations must coordinate their own maintenance with the generation of differentiated cell types to sustain organ physiology, in a spatially controlled manner and over long periods. Quantitative analyses of clonal dynamics have revealed that, in epithelia, homeostasis is achieved at the population rather than at the single stem cell level, suggesting that feedback mechanisms coordinate stem cell maintenance and progeny generation. In the central nervous system, however, little is known of the possible community processes underlying neural stem cell maintenance. Recent work, in part based on intravital imaging made possible in the adult zebrafish, conclusively highlights that homeostasis in neural stem cell pools may rely on population asymmetry and long-term spatiotemporal coordination of neural stem cell states and fates. These results suggest that neural stem cell assemblies in the vertebrate brain behave as self-organized systems, such that the stem cells themselves generate their own intrinsic niche.

Bloch Chirality Induced by an Interlayer Dzyaloshinskii-Moriya Interaction in Ferromagnetic Multilayers

Chiral spin textures stabilized by the interfacial Dzyaloshinkii-Moriya interaction, such as skyrmions and homochiral domain walls, have been shown to exhibit qualities that make them attractive for their incorporation in a variety of spintronic devices. However, for thicker multilayer films, mixed textures occur in which an achiral Bloch component coexists with a chiral Néel component of the domain wall to reduce the demagnetization field at the film surface. We show that an interlayer Dzyaloshinkii-Moriya interaction can break the degeneracy between Bloch chiralities. We further find large population asymmetries and chiral branching in the Bloch component of the domain walls in well-ordered Co/Pd multilayers. This asymmetry is a result of the combined effect of the demagnetization field and an interlayer Dzyaloshinkii-Moriya interaction, and is strongly related to film thickness and structural ordering. This work paves the way toward the utilization of this effect toward controlling Bloch chirality in magnetic multilayers.