Size Asymmetry Research Articles

Size Asymmetry in Multidomain Single Crystals and the Development of Curved Surfaces

Size Asymmetry in Multidomain Single Crystals and the Development of Curved Surfaces

7452 A Diagnostically Challenging Case of Hyperandrogenism in Postmenopausal Woman

Abstract Disclosure: M.S. Hossain: None. S. Hossain: None. B. Gautam: None. H. liao: None. S.C. Kumar: None. D.S. Rosenthal: None. Background: The diagnosis of new-onset severe hyperandrogenism in postmenopausal women is rarely encountered, posing a unique challenge for clinicians. Ovarian hyperthecosis and androgen-secreting tumors are the usual suspects in post menopause. In our case ovarian hyperthecosis is the primary consideration but elevated 17-OH Progesterone (17-OHP) introduces the potential co-existence of Non classical congenial adrenal hyperplasia (NCCAH) or rare instances of Sertoli-Leydig Cell Tumor (SLCT). Case Presentation: A 70 years old female, with no past medical history, referred to the Endocrinology clinic for significantly elevated testosterone level. She reported excessive hair growth in various areas of her body since 2022, which required shaving almost every day. She also reported male pattern hair loss and weight loss of 15 lbs over the last three months. She denied headache, vision changes, deepening of voice, history of fertility problems and use of exogenous testosterone. Her vital sign were normal. On examination, she had clitoromegaly, terminal hair growth on her upper lip and chin, breast atrophy, male pattern baldness, but no cushingoid or acromegaly features. Blood tests showed significantly elevated total testosterone: 1422 ng/dl (2-45); free testosterone: 147.9 pg/ml (0.2-3.7) and Estradiol: 64 pg/ml (Postmenopausal <31) with low LH: 7.6 mIU/ml (Postmenopausal 10.0-54.7) and FSH: 22.2 mIU/mL (Postmenopausal 23-116). Her serum ACTH, DHEA Sulfate, 11-deoxycortisol, 17 OH pregnenolone, TSH, Free T4, prolactin, IGF-1 were normal while her 17-OHP: 396 ng/dl (<45 ng/dl) was significantly elevated. An ACTH stimulation test showed 17-OHP level of 734 ng/dl at 30 minutes and 901 ng/dl at 1 hour. Pelvic ultrasonography: right ovary of 2.3 x 1.6 x 1.9 cm and the left ovary of 3.1 x 1.8 x 3.0 cm. MRI showed normal adrenal glands but a prominent left ovary. Patient was referred to the Obstetrics department to undergo bilateral oophorectomy for the definitive diagnosis and treatment. Discussion: The current ACTH stimulation test for non-classical congenital adrenal hyperplasia is validated for premenopausal women but lacks standardization in post-menopausal state. In our case, distinguishing the source of elevated 17-OHP between adrenal (NCCAH) and ovarian (SLCT) was difficult. Unexpected asymmetry in ovarian size observed in our case further complicates the scenario, contrasting with the typical symmetrical enlargement seen in ovarian hyperthecosis. Pending surgical pathology will further guide the management. This case highlights the complexity of diagnosing hyperandrogenism in postmenopausal women, emphasizing the significance of thoroughly exploring differential diagnoses and meticulously analyzing laboratory results. Presentation: 6/2/2024

Incidence and Impact of Component Size Asymmetry in Bilateral Total Knee Arthroplasty: A Prospective Study

Incidence and Impact of Component Size Asymmetry in Bilateral Total Knee Arthroplasty: A Prospective Study

Associations Between Developmental Stability, Canalization, and Phenotypic Plasticity in Response to Heterogeneous Experience.

The processes of developmental stability, canalization, and phenotypic plasticity have ecological and evolutionary significance, and been studied extensively, but mostly separately and thus the relationships between them are not straightforward. Our objective was to better integrate these processes in the context of temporally heterogeneous environments. We did this by investigating the effects of early experience with temporal heterogeneity in water availability on associations between developmental stability, canalization, and phenotypic plasticity. We subjected eight plant species to a first round of alternating inundation and drought vs. constantly moderate water treatments (heterogeneous experience) and a second round of water conditions (to test plasticity). We measured fluctuating asymmetry (FA) in leaf size, intra- and inter-individual variation (CVintra and CVinter), and plasticity (PI) in traits and analyzed correlations between these variables across all species. Results showed little correlations between FA, CVintra and PI, several positive correlations between FA and CVinter in more stressful conditions, especially in as well as positive correlations between CVinter and PI initially and negative correlations between them later. These suggested the complexity of these relationships, which can depend on whether plasticity occurs. Greater inter-individual variation will more likely cooperate with plasticity before or during plastic response, whereas higher canalization may reflect phenotypic convergence. Both higher FA and CVintra can reflect faster growth, while CVintra may also reflect plant growth stage, and the two mechanisms should cooperate in response to environmental challenges. The complexity of these relationships suggests plants deal with environmental variation in elaborate and integrative ways which can be affected by many factors.

Unionised dockworkers and port ownership structure in an international oligopoly

In an international duopoly with two markets and two ports, this paper investigates the role of dockworkers unionisation in determining the endogenous choice by governments of port ownership structure. While private ports maximise profits, public ports maximise domestic welfare and face a budget constraint, which is binding when unions are sufficiently wage-oriented and shipping costs are not too high. State-owned ports appear as the most likely equilibrium result although all possible configurations may arise in equilibrium, including an asymmetric structure with a state-owned port and a private port. Country size asymmetry, product differentiation and price competition in product markets favour the rise of a joint public ownership structure of ports. This structure also maximises domestic welfare when unions are wage-oriented.

Asymmetric vertical transport in weakly forced shallow flows

In this paper, we report on an investigation of the vertical transport of tracer particles released within a shallow, continuously-forced flow by means of numerical simulations. The investigation is motivated by the shallow flows encountered in many environmental situations and inspired by the laboratory experiments conducted in electromagnetically forced shallow fluid layers. The flow is confined to a thin fluid layer by stress-free top and no-slip bottom walls. The dynamics and the transport properties of the shallow flow are investigated under various flow conditions characterized by a Reynolds number related to the forcing, ReF, and the aspect ratio of vertical and horizontal length scales δ. The forcing generates an array of vortices that becomes unsteady when ReFδ2≳10. These vortices are accompanied by upwellings in their cores which are surrounded by narrower, stronger downwellings. Hence, upwellings occur where the horizontal flow is vorticity-dominated, while downwellings where it is strain-dominated. The magnitude of the asymmetry in strength and size of the vertical flows and their correlation with horizontal structures depends on the flow conditions and significantly influences the vertical spreading of particles within the fluid volume. Under conditions leading to a large asymmetry, particles within updrafts are transported slowly upwards, while particles within downdrafts rapidly move downwards. In addition, particles are trapped for longer within the updrafts than downdrafts because of their correlation with vorticity-dominated regions. However, when the flow becomes fully three-dimensional and highly unsteady for large ReFδ2 values, this transport asymmetry subsides because the updrafts and downdrafts exhibit similar strength and size in such flow conditions. Consequently, similar amounts of particles are transported upwards and downwards at similar rates.

From molecules to organisms: A multi-level approach shows negative effects of trace elements from sewage sludge used as soil improver on honeybees

The use of sewage sludge as a soil improver has been promoted in agroecosystems. However, sludges can contain toxic trace elements because of suboptimal wastewater treatment. Nonetheless, field studies investigating the negative effects of these practices on pollinators are lacking. We collected honeybees from an area where sewage sludge use is widespread, and one where it is precluded. Trace elements in soils and bees were quantified. Cadmium, chromium, lead, mercury, and nickel were investigated because they were the least correlated elements to each other and are known to be toxic. Their levels were related to oxidative stress and energy biomarkers, midgut epithelial health, body size and wing asymmetry of honeybees. We found increased carbohydrate content in sites with higher cadmium levels, increased histological damage to the midgut epithelium in the sewage sludge area, and the presence of dark spherites in the epithelium of bees collected from the sites with the highest lead levels. Finally, we found that honeybees with the highest lead content were smaller, and that wing fluctuating asymmetry increased in sites with increasing levels of mercury. To the best of our knowledge, this is the first comprehensive study of the concentration and effects on honeybees of trace elements potentially deriving from soil amendment practices.

Speed-up of the collective dynamics induced by non-observable components in binary suspensions of highly charged colloids

By light scattering, we study the collective dynamics of binary mixtures of charged colloids at low ionic strength. The size asymmetry between colloids gives us access to the intermediate scattering function corresponding to the big colloids. We find that the global dynamic correlations relax faster as the number of small undetectable components increases, and Brownian Dynamics numerical simulations confirm this finding. From simulations, we identify that the gradual softening of interparticle correlations, as the number of small colloids increases, is at the origin of the weakening of the measured dynamic correlations. Furthermore, we put forward a semi-empirical scheme to estimate the hydrodynamic interactions, allowing us to improve the comparison between the dynamic light scattering data and numerical simulation results.

Differential growth regulates asymmetric size partitioning in Caulobacter crescentus.

Cell size regulation has been extensively studied in symmetrically dividing cells, but the mechanisms underlying the control of size asymmetry in asymmetrically dividing bacteria remain elusive. Here, we examine the control of asymmetric division in Caulobacter crescentus, a bacterium that produces daughter cells with distinct fates and morphologies upon division. Through comprehensive analysis of multi-generational growth and shape data, we uncover a tightly regulated cell size partitioning mechanism. We find that errors in division site positioning are promptly corrected early in the division cycle through differential growth. Our analysis reveals a negative feedback between the size of daughter cell compartments and their growth rates, wherein the larger compartment grows slower to achieve a homeostatic size partitioning ratio at division. To explain these observations, we propose a mechanistic model of differential growth, in which equal amounts of growth regulators are partitioned into daughter cell compartments of unequal sizes and maintained over time via size-independent synthesis.

Mechanism of overscreening breakdown by molecular-scale electrode surface morphology in asymmetric ionic liquids

The interfacial nature of the electric double layer (EDL) assumes that electrode surface morphology significantly impacts the EDL properties. Since molecular-scale roughness modifies the structure of EDL, it is expected to disturb the overscreening effect and alter differential capacitance (DC). In this paper, we present a model that describes EDL near atomically rough electrodes with account for short-range electrostatic correlations. We provide numerical and analytical solutions for the analysis of conditions for the overscreening breakdown and DC shift estimation. Our findings reveal that electrode surface structure leads to DC decrease and can both break or enhance overscreening depending on the relation of surface roughness to electrostatic correlation length and ion size asymmetry.

Correlation between Component Size and Functional Knee Score in Patients Undergoing Bilateral Simultaneous Total Knee Arthroplasty: A Cross-Sectional Study

Abstract Background: Simultaneous bilateral total knee arthroplasty (simBTKA) has been a favored surgical solution to reduce costs and patient suffering. We aimed to evaluate the rate of asymmetry of component size in patients undergoing simBTKA and its impact on knee function as we believe that implant asymmetry may affect the functional outcomes in those patients. Methods: A cross-sectional study design was done on on 60 patients (120 knees) with simBTKA using patient-specific templating (PST). Patients were included if they had Kellgren–Lawrence Grade III-IV osteoarthritis. Revision surgeries, staged BTKA, or patients with bone defects, valgus deformity, severe varus deformity (defined as above 20°), and extra-articular deformities were excluded from the study. The outcome measures were interlimb component asymmetry, Knee Society Score (KSS), and range of motion (ROM). The comparison between pre- and postoperative findings was done using a dependent t-test. Results: A total of 29 (48.34%) patients had symmetrical femoral and tibial components, whereas the rest had asymmetry, of them, 11.7% had both femoral and tibial component size asymmetry. There were no statistically significant differences between the changes in KSS and ROM in the smaller implant and larger implant groups (P = 0.5 and P = 0.4, respectively). The total number of complications was eight and as follows: superficial infection, aseptic loosening, rupture of the patellar tendon after a bathroom fall, anemia requiring blood transfusion, residual varus deformity, deep venous thrombosis, periprosthetic fracture, and malalignment. Conclusion: There is no correlation between the interlimb component asymmetry and the knee function. However, there was statistically significant improvement from preoperative to postoperative KSS and ROM in small and large implants.

Human Male Body Size Predicts Increased Knockout Power, Which Is Accurately Tracked by Conspecific Judgments of Male Dominance

Humans have undergone a long evolutionary history of violent agonistic exchanges, which would have placed selective pressures on greater body size and the psychophysical systems that detect them. The present work showed that greater body size in humans predicted increased knockout power during combative contests (Study 1a-1b: total N = 5,866; Study 2: N = 44 openweight fights). In agonistic exchanges reflective of ancestral size asymmetries, heavier combatants were 200% more likely to win against their lighter counterparts because they were 200% more likely to knock them out (Study 2). Human dominance judgments (total N = 500 MTurkers) accurately tracked the frequency with which men (N = 516) knocked out similar-sized adversaries (Study 3). Humans were able to directly perceive a man’s knockout power because they were attending to cues of a man’s body size. Human dominance judgments—which are important across numerous psychological domains, including attractiveness, leadership, and legal decision-making—accurately predict the likelihood with which a potential mate, ally, or rival can incapacitate their adversaries.

Diagnostic Approach to Equine Testicular Disorders.

Management of breeding stallions is crucial to equine reproduction. The longevity of the breeding career is the ultimate objective, whether the stallion is used for natural cover or for semen collection and artificial insemination. Stud farm veterinarians should be aware of the techniques used to evaluate testicular function and the diagnostic approach to testicular disorders in cases of emergency. This paper presents the clinical methods used to evaluate testicular health, including palpation, ultrasonography, biopsy, and fine-needle aspiration. The discussion of testicular disorders is broken down into four categories: congenital disorders (cryptorchidism, monorchidism, and testicular hypoplasia), differential diagnosis of scrotal enlargement, differential diagnosis of causes of progressive testicular enlargement, and differential diagnosis of testicular asymmetry or reduction in size with an emphasis on testicular degeneration. The sudden increase in testicular size is often accompanied by severe clinical signs and is a major cause for referral of stallion for surgery. Testicular disorders are illustrated with clinical cases seen by the authors.

NMY-2, TOE-2 and PIG-1 regulate Caenorhabditis elegans asymmetric cell divisions.

Asymmetric cell division is an important mechanism that generates cellular diversity during development. Not only do asymmetric cell divisions produce daughter cells of different fates, but many can also produce daughters of different sizes, which we refer to as Daughter Cell Size Asymmetry (DCSA). In Caenorhabditis elegans, apoptotic cells are frequently produced by asymmetric divisions that exhibit DCSA, where the smaller daughter dies. We focus here on the divisions of the Q.a and Q.p neuroblasts, which produce larger surviving cells and smaller apoptotic cells and divide with opposite polarity using both distinct and overlapping mechanisms. Several proteins regulate DCSA in these divisions. Previous studies showed that the PIG-1/MELK and TOE-2 proteins regulate DCSA in both the Q.a and Q.p divisions, and the non-muscle myosin NMY-2 regulates DCSA in the Q.a division but not the Q.p division. In this study, we examined endogenously tagged NMY-2, TOE-2, and PIG-1 reporters and characterized their distribution at the cortex during the Q.a and Q.p divisions. In both divisions, TOE-2 localized toward the side of the dividing cell that produced the smaller daughter, whereas PIG-1 localized toward the side that produced the larger daughter. As previously reported, NMY-2 localized to the side of Q.a that produced the smaller daughter and did not localize asymmetrically in Q.p. We used temperature-sensitive nmy-2 mutants to determine the role of nmy-2 in these divisions and were surprised to find that these mutants only displayed DCSA defects in the Q.p division. We generated double mutant combinations between the nmy-2 mutations and mutations in toe-2 and pig-1. Because previous studies indicate that DCSA defects result in the transformation of cells fated to die into their sister cells, the finding that the nmy-2 mutations did not significantly alter the Q.a and Q.p DCSA defects of toe-2 and pig-1 mutants but did alter the number of daughter cells produced by Q.a and Q.p suggests that nmy-2 plays a role in specifying the fates of the Q.a and Q.p that is independent of its role in DCSA.

Abstract PO2-02-14: Development of a multi-institutional, photograph-rich clinical dataset to test and validate a novel inflammatory breast cancer (IBC) scoring system

Abstract Purpose: Susan G. Komen, The Inflammatory Breast Cancer (IBC) Research Foundation, and the Milburn Foundation convened a collaborative of patient advocates, clinicians, and researchers and proposed a novel quantitative scoring system for IBC diagnosis. The score includes timing of symptoms, extent of skin edema and erythema/other discoloration, breast and nipple asymmetry, lympho-vascular space invasion, nodal stage, and diffuse extent disease in the breast on breast imaging. Total scores were categorized (< 14 Not IBC, 14-24 Weak Possibility of IBC, 25-41 Strong Possibility of IBC, > 41 Definitely IBC). Herein, we developed a multi-institutional clinical dataset to retrospectively test and validate the proposed scoring system. Methods: IBC (N= 988) and non-IBC (N=322) cases were identified at two institutions with dedicated multi-disciplinary IBC programs, UT MD Anderson Cancer Center (MDA) and Dana-Farber Cancer Institute (DFCI). The DFCI cohort was diagnosed from 1986-2021 and the MDA cohort was diagnosed from 2010-2020. The non-IBC cohorts were identified as consecutive T4b and T4c cases in existing retrospective databases. Photographs were reviewed for available cases. All scoring variables were reviewed with data extractors and standard operating procedures (SOPs) developed for all ambiguous findings and language. A subset of scores were reviewed by IBC clinicians (FL, WW) and discrepancies discussed to inform the SOPs. Missing data imputation using three methods was examined. Area under the curve (AUC) - Receiver operator characteristic (ROC) curves and values, and sensitivity and specificity for the proposed score cut offs were examined. Results: Of 1320 patients currently in the analysis, 421 (31.9%) have missing data on > 1 characteristics and 47 (3.6%) are missing data on > 4. The rubric characteristic most commonly missing was “nipple abnormalities” accounting for 21.0% and 19.3% for IBC and non-IBC cohorts respectively. Unavailable bilateral breast photograph was the primary source of missing data. The highest scoring finding was present in the following percentage of IBC and non-IBC cases, respectively: timing of symptom onset < 3 months (74.1% vs 38.6%), any peau d’orange (61.2% vs 30.1%), clinically apparent enlargement or new asymmetry of breast size (87.8% vs 90.1%), complete or near complete involvement of the breast skin by erythema or discoloration (55.6% vs 25.6%), new nipple inversion (24.6% vs 9.0%), dermal lymphovascular emboli present (17.9% vs 1.8%), diffuse involvement of the breast parenchyma by imaging (72% vs 77.7%). True IBC cases were categorized as Definitely IBC, Strong Possibility, Weak Possibility, not IBC and unknown 19.7%, 49.1%, 0.4%, 0.1%, and 30.7%. True non-IBC were 0.6%, 51.8%, 9.9%, 2.1%, and 35.5%. Random imputation, lowest value imputation, and median value imputation were compared to impute missing data. AUC-ROC values for each method were similar, 0.80 - 0.84. Conclusion: We describe the development of the largest multi-institutional IBC clinical database to date. SOPs for the rubric characteristics were developed. The importance of bilateral photography to assess the score retrospectively is highlighted. The score is associated with a good AUC-ROC but still leaves much overlap among cases between 25 and 42. Further optimization of the current scoring system and association with outcomes are in progress. Citation Format: Filipa Lynce, Samuel Niman, Megumi Kai, Sean Ryan, Elizabeth Troll, Li Li, Kathy Miller, Reshma Jagsi, Ginny Mason, Beth Overmoyer, H. T. Carisa Le-Petross, Faina Nakhlis, Savitri Krishnamurthy, Beth Harrison, Susie X. Sun, Eren Yeh, Jennifer Bellon, Laura Warren, Michael Stauder, Meredith Regan, Wendy Woodward. Development of a multi-institutional, photograph-rich clinical dataset to test and validate a novel inflammatory breast cancer (IBC) scoring system [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-02-14.

Should paediatric tonsillar asymmetry be an indication for tonsillectomy? A single centre experience.

Paediatric tonsillar lymphoma (TL) is a rare diagnosis. Historically, the presence of clinical features such as tonsillar asymmetry, grossly abnormal tonsil appearance and cervical lymphadenopathy raise concern for this diagnosis. Tonsillar asymmetry is considered to be the most concerning clinical feature; however, asymmetry is often apparent due to differences in depth or shape of tonsillar fossa and tonsillar pillars, rather than a true difference in volume. There is debate whether a tonsillectomy is required in all cases of tonsil asymmetry to exclude lymphoma, and what clinical features should raise concern. The aim of this study was to establish whether the presence of clinical asymmetry can be deemed a reliable marker for genuine tonsil size discrepancies. We also sought to evaluate the clinical and examination characteristics that are concerning for lymphoma. Retrospective review of clinical records for paediatric tonsil specimens sent for histological evaluation between 1 January 2012 and 1 January 2023 driven by a clinical suspicion of lymphoma at Starship Children's Hospital, New Zealand. Patient demographics and clinical data were recorded. A comparison was made between tonsil size asymmetry on clinical examination (Brodsky criteria) and tonsil volume difference based on dimensions given in pathology reports. One hundred and forty-three patients had tonsillectomies between 2012 and 2022 at Starship Children's Hospital due to concern for lymphoma. Of these, three were positive for lymphoma. Presence of pain and abnormal tonsil appearance were predictors for lymphoma (p<0.02). Interrater reliability agreement between clinical size difference and tonsil volume was poor, Kappa= -0.13 p<0.05. Clinical size difference is a poor predictor for true tonsil volume difference. We advise that assessment of tonsil size should be performed in conjunction with the examination of gross visual abnormalities and lymphadenopathy to guide clinical decision making.

Asymmetry in linear measurements and cross-sectional geometry in the humerus during ontogeny.

Adult upper limb asymmetry is used to reconstruct behavior. However, the developmental trajectory of asymmetry in bone length, cross-sectional geometry (CSG), and joint dimensions is poorly understood. This study examines the development trajectory of humeral asymmetry and if asymmetry in bone length, joint size, and CSG develop in concert. Linear measurements of bone length and metaphyseal/epiphyseal breadth, bending rigidity (Imax and Imin), and cross-sectional shape (Imax/Imin) at 30%, 50%, and 70% of bone length were acquired from 3D models of humeri from four skeletal samples of prehistoric hunter-gatherer populations (n = 82). Dental age cohorts were used to assess ontogenetic trends. Percent absolute (%AA) and directional (%DA) asymmetry were calculated for paired measures. Percentage of matching direction of asymmetry across variables and correlation analysis tested relationships between variables. Within the total pooled sample, Imax shows the highest %AA and %DA, followed by shape and linear dimensions. Asymmetry is lowest in neonates and increases with age, particularly %DA of Imax in mid-proximal sections. Correlations among variables are low to moderate and strongest between Imax measures. Matching direction of asymmetry between variables is low and generally increases with age. Higher correlations with age in CSG likely indicate greater responsiveness to mechanical loading. Low correlations in magnitude of asymmetry and side dominance suggest independence in the development of asymmetry between maximum rigidity, shape, and linear measures. Differences in how asymmetric loading affects the ontogeny of linear and CSG variables may account for the heterogeneous development of asymmetry.

Inter-arm bone mass and size asymmetries in children tennis players are maturity status specific: a 9-month study on the effects of training time across pubertal change and somatic growth

PurposeBone growth with exercise is best assessed by tennis-induced inter-arm asymmetries. Yet, the effects of training and maturation across puberty were unclear. This study explored arm bone growth across 9 months of training in 46 tennis players 7–14 years (25 boys, 21 girls).MethodsBone mineral content (BMC) and bone area (BA) were measured from DXA scans. Pubertal status was assessed by Tanner stage (TS) and somatic growth by maturity offset (MO). Children were grouped as pre- (TS I–I), early (TS I–II), and mid/late pubertal (TS II–III).ResultsTraining time (TT) change in the three groups was 160–170, 190–230, and 200–220 h, respectively. Bone asymmetries were large in all groups (d > 0.8, P < 0.001): 5–18 g (9–21%) and 9–17 g (17–23%) in girls and boys, respectively, for BMC, and 5–15 cm2 (6–13%) and 9–15 cm2 (12–15%) in girls and boys (10–13%), respectively, for BA. BMC and BA change asymmetry peaked at pre-puberty in girls (56%, 46%) and at early puberty in boys (57%, 43%). Asymmetry gains varied with baseline asymmetry (41%) and change in TT (38%) and TS (17%) in BMC, and with baseline asymmetry (58%) and change in MO (17%) and TS (12%) in BA.ConclusionAll bone asymmetries were substantial. Tennis-induced bone gains were higher at pre- to early puberty in girls and at early to mid/late puberty in boys. Training enhanced mostly bone mass and maturity status enhanced mostly bone size; sex was not bone-change modeling impactful. Implications are discussed considering certain limitations.

Choosing a bigger opponent: the path to victory and greater gains for the small contestant

Animals often engage in contests over limited resources. The probability of winning a contest is primarily determined by the individual's fighting ability relative to its opponent and the perceived value of the disputed resource. Individuals of the hermit crab Calcinus californiensis frequently fight over gastropod shells. We conducted a free-choice experiment to assess the factors that determine individuals’ choice of opponent, contest initiation, and contest resolution. We placed hermit crabs occupying two shell species into a large container and monitored agonistic interactions between crabs. We assessed the asymmetries in fighting ability based on the differences in body mass between the opponents. The shell species and fit (i.e., shell size relative to crab body size) were used as measures of the objective and subjective resource value, respectively. Motivation influenced contest initiation; the crabs occupying too-tight shells were more likely to initiate a contest than the ones in looser-fitting shells. In most cases, the attackers fought for a shell with a looser fit, even if that meant losing a tighter-fitting shell of the preferred shell species. The fighting success for attackers was positively associated with the number of bouts of rapping and the shell size improvement. However, success was negatively correlated with body size asymmetry; attackers that chose opponents larger than themselves were more likely to evict their opponent than the attackers that chose opponents that were smaller. Experimental designs that allow animals to select their own opponents, rather than assigning specific opponents, can strongly contribute to knowledge of agonistic interactions.Significance statementFighting dynamics are commonly assessed by estimating the influence of the resource-holding potential and resource value in pair-matched opponents. Here, however, we examined the influence of asymmetries in resource-holding potential and the objective and subjective value of gastropod shells on the choice of a contender and contest resolution through a free-choice opponent experiment in hermit crabs. The contest initiation was driven by the motivation to obtain a better gastropod shell species or one with a better size fit—factors which are known to improve individual fitness. Furthermore, fighting success was associated with an individual's persistence in displaying aggressive behaviors and its motivation to obtain a better resource. However, contrary to the predictions of game theoretical models, fighting success was higher when attackers chose opponents larger than themselves. Our results highlight the relevance of assessing fighting under more natural conditions by allowing animals to select their opponents.

Aggressiveness overcomes body‐size effects in contests between native and invasive cichlid fishes

AbstractIn animal fights, there are often size asymmetries between opponents. Although larger individuals typically dominate smaller ones, size is not the sole determining factor, as the competitors' motivation, aggressiveness, resource value, physiological characteristics, and strength also play crucial roles in fighting outcomes. In this study, we evaluated the influence of body size on dominance hierarchy and contest success during intra‐ and inter‐specific contests in two fish species: the native mojarra of the Balsas basin Amphilophus istlanus and the invasive convict cichlid Amatitlania nigrofasciata. We used size‐asymmetric males to carry out experimental contests. The number and type of aggressive behaviors, time to contest outcome, and dominant individual at the end of the contest were determined. In contests between two native mojarra, the smaller individual always lost. In contests between convict cichlids, the smaller contestants lost in all contests where size asymmetry was greater than 20%. In interspecific contests, the native mojarra performed more aggressive behaviors than the invasive convict cichlid and dominated convict cichlids despite a size disadvantage. This suggests that in terms of competition via interference, the native mojarra can counter the arrival of the invasive convict cichlid.