Mixed-sex Groups Research Articles

Mice employ a bait-and-switch escape mechanism to de-escalate social conflict.

Intraspecies aggression has profound ecological and evolutionary consequences, as recipients can suffer injuries, decreases in fitness, and become outcasts from social groups. Although animals implement diverse strategies to avoid hostile confrontations, the extent to which social influences affect escape tactics is unclear. Here, we used computational and machine-learning approaches to analyze complex behavioral interactions as mixed-sex groups of mice, Mus musculus, freely interacted. Mice displayed a rich repertoire of behaviors marked by changes in behavioral state, aggressive encounters, and mixed-sex interactions. A distinctive behavioral sequence consistently occurred after aggressive encounters, where males in submissive states quickly approached and transiently interacted with females immediately before the aggressor engaged with the same female. The behavioral sequences were also associated with substantially fewer physical altercations. Furthermore, the male's behavioral state could be predicted by distinct features of the behavioral sequence, such as kinematics and the latency to and duration of male-female interactions. More broadly, our work revealed an ethologically relevant escape strategy influenced by the presence of females that may serve as a mechanism for de-escalating social conflict and preventing consequential reductions in fitness.

The hows and whys of gendered grouping practices in primary physical education in England

ABSTRACT Background: Single- and mixed-sex grouping have long been a focus of attention in physical education (PE) and are matters often at the fore of discussions about curriculum planning, teaching, and learning. Nonetheless, there remains little consensus or guidance on which approach (or combination of approaches) should be preferred in PE in primary and secondary schools in England. Further, while single- and mixed-sex grouping have been extensively researched in PE in secondary schools, hitherto there remains an absence of research examining these practices in PE in primary schools. This research sought to address gaps in the literature to build a stronger evidence-base for decisions about gendered grouping practices in PE. Specifically, the study was designed to provide a snapshot of current single- and mixed-sex grouping arrangements in primary PE in England. Method: Data were collected via an online survey which was administered to all state-funded mainstream and special schools providing for children in Key Stage 1 (aged 5–7) and/or Key Stage 2 (aged 7–11) in the North-East of England (917 at the time of study). A total of 254 surveys were completed giving a response rate of 27.7%. Results: The responses indicate that nearly all schools were using mixed-sex grouping for PE, with children typically remaining in their mixed-sex form class and taught the same curriculum activities by their class teacher. Notably, no schools were using single-sex grouping for all PE lessons, although some were teaching combinations of single- and mixed-sex classes across different year groups and/or different activities of the curriculum. The responses also challenge the traditional dichotomous representation of single- and mixed-sex grouping by showing that some schools were grouping children into smaller single-sex groups within mixed-sex PE classes, particularly in activities requiring bodily contact. Some schools were also organising children into smaller mixed-sex groups within mixed-sex PE classes to encourage boys and girls to work together and support one another in their learning. Reported reasons for current grouping arrangements reflected both pragmatic considerations and perceived educational benefits of particular approaches, including school timetabling and consideration of gender equity in curriculum provision in PE. Conclusion: The conclusion calls for further research to explore the efficacy of single- and/or mixed-sex grouping in supporting and meeting the needs of all children in primary PE. Relatedly, we also highlight the importance of intersectional perspectives being brought to single- and mixed-sex grouping debates to inform the development of more nuanced, evidence-based policies and practices that promote inclusion and celebrate the diversity of children. We further suggest a need for research and policy to reconsider the language used in grouping practices to reflect commitments to gender diversity and gender equity.

Exercise-based interventions targeting balance and falls in people with COPD: a systematic review and meta-analysis.

This review quantifies the mean treatment effect of exercise-based interventions on balance and falls risk in people with COPD. A structured search strategy (2000-2023) was applied to eight databases to identify studies evaluating the impact of exercise-based interventions (≥14 days in duration) on balance or falls in people with COPD. Pooled mean treatment effects (95% confidence intervals (CIs), 95% prediction intervals (PIs)) were calculated for outcomes reported in five or more studies. Inter-individual response variance and the promise of behaviour change techniques (BCTs) were explored. 34 studies (n=1712) were included. There were greater improvements in balance post intervention compared to controls for the Berg Balance Scale (BBS) (mean 2.51, 95% CI 0.22-4.80, 95% PI -4.60-9.63), Timed Up and Go (TUG) test (mean -1.12 s, 95% CI -1.69- -0.55 s, 95% PI -2.78-0.54 s), Single-Leg Stance (SLS) test (mean 3.25 s, 95% CI 2.72-3.77 s, 95% PI 2.64-3.86 s) and Activities-specific Balance Confidence (ABC) scale (mean 8.50%, 95% CI 2.41-14.58%, 95% PI -8.92-25.92%). Effect on falls remains unknown. Treatment effects were larger in male versus mixed-sex groups for the ABC scale and SLS test, and in balance training versus other exercise-based interventions for the BBS and TUG test. Falls history was not associated with changes in balance. Meta-analysis of individual response variance was not possible and study-level results were inconclusive. Eleven promising BCTs were identified (promise ratio ≥2). Evidence for the effect of exercise-based interventions eliciting clinically important improvements in balance for people with COPD is weak, but targeted balance training produces the greatest benefits. Future exercise interventions may benefit from inclusion of the identified promising BCTs.

Observations of reproductive behaviors in the Critically Endangered bowmouth guitarfish Rhina ancylostoma

Wedgefishes, family Rhinidae, are collectively identified as one of the most threatened groups of chondrichthyan fishes globally by the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species. Within the family Rhinidae, bowmouth guitarfish Rhina ancylostoma have been designated by the IUCN as Critically Endangered since 2018. Bowmouth guitarfish were first introduced to the Association of Zoos and Aquariums (AZA) in 2005 when the Newport Aquarium, Newport, KY, USA, acquired a single female. In 2007, a male bowmouth guitarfish was added into the collection with the goal of establishing an institutional breeding program and to generate foundational knowledge for future breeding programs. This study presents an ethogram of mating behaviors exhibited by a mixed sex group of bowmouth guitarfish using behavioral observations from December 2017 through August 2022. The observed interactions between male and female bowmouth guitarfish led to the identification of 5 male reproductive behaviors: hovering, chasing, wrapping up, flipping/rolling, and copulation. These 5 behaviors were directly linked with successful reproduction, e.g. active breeding and live parturition, in the imperiled species R. ancylostoma. The breeding behavioral knowledge presented within this study provides the first step to a viable breeding program, a critical tool for conserving wild populations.

The ability to inhibit impulses is related to social behavior in long-tailed macaques.

Performance in cognitive tasks has been linked to differences in species' social organization, yet to understand its function its relationship to within-species variation in behavior should also be explored. One important cognitive capacity, the ability to inhibit impulses, is typically better in egalitarian than despotic primate species and in primate species with strong fission-fusion dynamics. A different line of research indicates that a high ability to inhibit impulses is related to less aggressive behavior and more socio-positive behavior. However, within species the relationship between performance on cognitive inhibition tasks and variation in social behavior remains to be explored. Here we investigate how performance in a typical inhibition task in cognitive research is related to aggressive and socio-positive behavior in despotic long-tailed macaques. Twenty individuals living in two naturalistic mixed-sex groups were tested with the Plexiglass Hole Task. Aggressive behavior and three types of socio-positive behavior (neutral/friendly approaches, socio-positive signaling, and grooming others) among group members were measured. Individuals differed in their ability to inhibit impulses. Individuals that were not good at inhibiting impulses showed higher rates of aggressive behavior, but also more socio-positive signals, whereas inhibition was not related to neutral/friendly approaches and grooming. These results confirm the positive link between impulsiveness and aggression. In addition, the results indicate that some social-positive behavior may be enhanced when inhibition is limited. In this species, benefits potentially derived from aggression and socio-positive signals match a low ability to inhibit impulses, suggesting that a low ability to inhibit impulses may actually be advantageous. To understand differences between species in cognitive skills, understanding the benefits of variation in a cognitive capacity within a species is crucial.

Early life social complexity shapes adult neural processing in the communal spiny mouse Acomys cahirinus.

Early life social rearing has profound consequences on offspring behavior and resilience. Yet, most studies examining early life development in rodents use species whose young are born immobile and do not produce complex social behavior until later in development. Furthermore, models of rearing under increased social complexity, rather than deprivation, are needed to provide alternative insight into the development of social neural circuitry. To understand precocial offspring social development, we manipulated early life social complexity in the communal spiny mouse Acomys cahirinus and assessed long-term consequences on offspring social behavior, exploration, and neural responses to novel social stimuli. Spiny mouse pups were raised in the presence or absence of a non-kin breeding group. Upon adulthood, subjects underwent social interaction tests, an open field test, and a novel object test. Subjects were then exposed to a novel conspecific and novel group and neural responses were quantified via immunohistochemical staining in brain regions associated with social behavior. Early life social experience did not influence behavior in the test battery, but it did influence social processing. In animals exposed to non-kin during development, adult lateral septal neural responses toward a novel conspecific were weaker and hypothalamic neural responses toward a mixed-sex group were stronger. Communal species may exhibit robust behavioral resilience to the early life social environment. But the early life environment can affect how novel social information is processed in the brain during adulthood, with long-term consequences that are likely to shape their behavioral trajectory.

Savory Cracker Development for Blood Glucose Control and Management: Glycogen Storage Diseases.

The blood glucose response of savory slow energy-release crackers (GLY-HYP) were evaluated in volunteers carrying glycogen storage diseases (GSDs), Types I (Ia) and IV. The crackers have been shown previously to provide a "flat" slow glucose response in healthy volunteers, for up to 4 h. On average for the mixed-sex volunteer group aged 53 to 70 for Type I, the blood glucose concentration increased from baseline to a maximum of 9.5 mmol/L at 60 min and remained above baseline for up to 210 min; overall, above 5 mmol/L for 4 h. In common with healthy individuals, a relatively flat blood glucose response was recorded. For Type IV, mixed-sex patients aged between 55 and 72, the blood glucose concentration reached maximum of 10.2 mmol/L at 45 min and then stayed above baseline for 150 min. Again, overall, above 5 mmol/L for 4 h. Altogether, these data indicate that these crackers would provide a valuable contribution to the nutritional needs of people of different age groups with GSDs (Clinical Registration Number: HRC10032021).

Life Span Changes of Coffee White Stem Borers, Xylotrechus quadripes (Coleoptera: Cerambycidae) in Response to Directed Homosexual and Heterosexual Interactions

Our study on coffee white stem borers, Xylotrechus quadripes investigated the influence of different sex-based clustering factors on beetle survivorship and life spans. Our experiments involved various groups, including individually isolated virgin males, individually isolated virgin females, groups of only males, groups of only females, and mixed-sex groups. First, survivorship reached 100% within the initial 15 days for all groups except for isolated virgin males. In contrast, the survivorship rates of both groups involving only virgin females and only virgin males ranged from 80% to 90% compared to the maximum survival duration. Notably, in scenarios with males in groups or mixed-gender groups, survival dropped to zero percent after 45 days. Our study also highlighted the comparable costs incurred by males engaging in both homosexual and heterosexual interactions. Males interacting with females and other males exhibited similar survival curves, displaying shorter median life spans compared to isolated virgin males, suggesting that both courting and mounting behaviors, regardless of the recipient's sex, might affect the life span of males. Furthermore, our research revealed that female-female interactions, while less costly than male-male interactions, still reduced survival periods in only the female group. These findings highlight the cost possibly associated with same-sex interactions and shed light on the dynamics of mating behaviors in this beetle. In conclusion, our findings underscore the significance of studying behavioral and life history traits in different environmental contexts. Social circumstances and ecological factors significantly influence sexual differences in lifespan and highlight the complexity of the interplay between reproductive strategies and survival rates in Xylotrechus quadripes.

Combined estrogen and elevated temperature treatments induce feminization in Nile tilapia, Oreochromis niloticus

Nile tilapia has proven to be sensitive to change phenotypic sex upon exposure to steroid hormone and high temperature during the critical period of gonad differentiation. It is more difficult to feminize XY males than to masculinize XX females. High temperature feminization has also been observed in very few cases in Nile tilapia. Therefore, this study was designed to increase the feminization rates using combined treatments of estrogen hormone (either diethylstilbestrol, DES, or 17α-ethynylestradiol, EE2) and high temperature (36 oC) during the sensitive period of gonad differentiation in Nile tilapia. The parents genotype of the crosses was XX♀ × XY♂; XX♀ × YY♂ and XX♀ × XX♂. Progenies from each cross were exposed to one of six types of treatments: (i) combined treatment of estrogen hormone (DES or EE2) and high temperature (36 oC) (ii) hormone (DES or EE2) alone as positive control (iii) 36 oC as positive control and (iv) 28 oC as negative control. The sexual genotype was confirmed using tightly sex-linked markers located in linkage groups (LG) 1, LG20 and LG23. Both of the combined treatments of estrogen hormone (either DES or EE2) and high temperature induced significant feminization compared with hormone alone in all the crosses except XX (all female progeny). The combined hormone and high temperature treatment using DES showed 100% feminization rate in mixed sex group. On the other hand, high temperature treatment with EE2 showed 75% (100 mg/kg feed) and 65% (150 mg/kg feed) feminization rate in mixed sex group whereas in XY progeny group c. 19% (100 mg/kg feed) and c. 22% (150 mg/kg feed) feminization percentage were observed. However, the survival rate in the negative control ranged from 79% to 96% whereas the EE2-high temperature combined treatment showed higher survival rate (ranged from 79% to 94%) than in the DES-high temperature combined treatment (46.88% in mixed sex group). Similarly, survival rate was also higher in EE2 alone (ranged from 73% to 96%) than in DES alone treatment (c. 66%). DES hormone alone showed higher percentage of feminization (57.14%) than EE2 whereas EE2 hormone alone showed variable results and induced feminization (38.89%) in only one of the batches produced (mixed sex progeny treated with 150 mg/kg feed). High temperature masculinization was observed in one of the mixed sex crosses produced (40%) and in the XX cross (30%). This is the first study demonstrating that combined treatment of estrogen hormone and elevated temperature induced higher feminization rates in Nile tilapia than hormone alone, despite the generally opposite effect of the estrogen hormone and high temperature on gonad differentiation pathways in Nile tilapia.

Crossing the Old Local Breed Deutsches Lachshuhn with the Layer Breed White Rock: Effects on Laying Performance of the Females and Fattening Performance of the Males.

We tested the novel cross of the old local breed Deutsches Lachshuhn and the layer breed White Rock, as well as purebred Deutsches Lachshuhn, for their suitability as dual-purpose chickens under 100% organic husbandry conditions, and compared their performance and welfare with the two dual-purpose crosses New Hampshire × Bresse and Bresse × White Rock, which are already established in Germany. Chicks were reared in mixed-sex groups until slaughter of the males at 15 or 18 weeks of life. Data on laying performance and animal welfare were recorded until the hens' 72nd week of life. Laying performance of Deutsches Lachshuhn × White Rock was almost twice as high as that in purebred hens, while fattening performance of the males did not differ. Deutsches Lachshuhn × White Rock, New Hampshire × Bresse and Bresse × White Rock realized a balanced performance profile of 242-250 eggs per hen alive and a final live weight of the males of 2924-3105 g after 18 weeks of rearing. The efficiency of a pair of chickens (one male and one female) was very similar for the crosses (3.69-3.77 kg feed kg-1 marketable product), while purebred Deutsches Lachshuhn was less efficient (6.35 kg feed kg-1 marketable product). Crossing the breed Deutsches Lachshuhn with a layer breed therefore improved laying performance and overall efficiency of the birds compared to purebred Deutsches Lachshuhn.

Guarding success of the rarest sex in the amphipodHyalella aztecaSaussure, 1858 (Amphipoda: Hyalellidae)

AbstractTraditional methods to study precopulatory mate guarding in Hyalella azteca (Saussure, 1858) have some limitations because precopulatory pairs are usually observed in isolation. This condition precludes researchers from testing the role of the social environment in the duration of precopulatory mate guarding. We present the use of a sampling method to investigate the influence of sex ratios on guarding success (the proportion of precopulatory pairs per trial) in mixed-sex groups of H. azteca. The presence/absence of precopulatory pairs over eight consecutive days, morning and afternoon samplings, was analysed as a series of successes (runs) to estimate the mean precopula duration. The non-random nature of the observed duration of the precopula was tested against a probabilistic distribution based on the set of all ways every possible duration may occur. While skewed sex ratios increased guarding success of the rarest sex, even sex ratios decreased it. The mean duration of observed precopulas (2.32 and 2.08 d for the morning and afternoon periods, respectively) is consistent with theoretical and empirical results, which confirms the accuracy and usefulness of the sampling method we used. The use of this method and the associated probabilistic analysis of the relevant data can enhance the study of the effect of biotic and abiotic factors on precopulatory mate guarding. It can also be used to test predictions derived from hypothesis concerned with mate guarding among crustaceans.

Effect of mixed-sex play on pupils’ attitudes towards schooling in public and private schools in Oyo state, Nigeria

This study examined how mixed-sex play affected students' attitudes toward schooling in both private and state primary schools in Oyo State, Nigeria. Participants in a pre-test, post-test control group quasi-experimental research design with a 2x2 factorial matrix were randomly assigned to the experimental and control groups. For eight weeks, participants met for a weekly one-hour session. Using the Pupil Attitude Questionnaire, data were gathered. The significance level used to evaluate the results was.05. Utilizing Analysis of Covariance, data were examined. The study's findings showed a substantial treatment effect on pupils' attitudes toward schooling (F (1,149) = 340.567; p < .05), with students in the mixed-sex play group showing the greatest improvement. Additionally, it was discovered that treatment and school type had a two-way interaction impact (F (1,149) = 4.445; p < .05). No significant school type effect (F (1,149) = 2.093; p > .05) was observed. It was concluded that mixed-sex play has significant effect on attitudes towards schooling among primary school pupils and that same was influenced by school type. It was therefore recommended that while mixed-sex play could be used with gains in public schools, efforts should be made to see how it could be significantly deployed to the advantage of private school pupils.

Instrumental Flirting: An Exploration of Charm in Decision-Making Groups.

The scholarship on flirting as a persuasive tactic in the workplace indicates that flirting can have negative consequences for task groups. The goal of this study was to extend the investigation of instrumental flirting by operationalizing this form of flirting as charm and by examining the consequences of charm in decision-making groups for the individual group members. In the current study, participants (60 women, 60 men) made decisions in four-person, mixed sex groups. The results of the study demonstrate that the use of charm was negatively associated with perceptions of group member task competence. Differences in perceptions of charm were also examined.

Sexual health and serotonin 4 receptor brain binding in unmedicated patients with depression—a NeuroPharm study

Sexual dysfunction is prominent in Major Depressive Disorder (MDD) and affects women with depression more than men. Patients with MDD relative to healthy controls have lower brain levels of the serotonin 4 receptor (5-HT4R), which is expressed with high density in the striatum, i.e. a key hub of the reward system. Reduced sexual desire is putatively related to disturbed reward processing and may index anhedonia in MDD. Here, we aim to illuminate plausible underlying neurobiology of sexual dysfunction in unmedicated patients with MDD. We map associations between 5-HT4R binding, as imaged with [11C]SB207145 PET, in the striatum, and self-reported sexual function. We also evaluate if pre-treatment sexual desire score predicts 8-week treatment outcome in women. From the NeuroPharm study, we include 85 untreated MDD patients (71% women) who underwent eight weeks of antidepressant drug treatment. In the mixed sex group, we find no difference in 5-HT4R binding between patients with sexual dysfunction vs normal sexual function. However, in women we find lower 5-HT4R binding in the sexual dysfunctional group compared to women with normal sexual function (β = −0.36, 95%CI[−0.62:−0.09], p = 0.009) as well as a positive association between sexual desire and 5-HT4R binding (β = 0.07, 95%CI [0.02:0.13], p = 0.012). Sexual desire at baseline do not predict treatment outcome (ROC curve AUC = 52%[36%:67%]) in women. Taken together, we find evidence for a positive association between sexual desire and striatal 5-HT4R availability in women with depression. Interestingly, this raises the question if direct 5-HT4R agonism can target reduced sexual desire or anhedonia in MDD.

Research on Space Occupancy, Activity Rhythm and Sexual Segregation of White-Lipped Deer (Cervus albirostris) in Forest Habitats of Jiacha Gorge on Yarlung Zangbo River Basin Based on Infrared Camera Technology.

The white-lipped deer (Cervus albirostris) is a rare and endangered species found in the Qinghai-Tibet Plateau in China. To understand the space occupancy, activity rhythm, and sexual segregation of the white-lipped deer, 24,096 effective photos and 827 effective videos were captured using infrared cameras from February 2020 to January 2022. The ecology and behavior of the white-lipped deer in Jiacha Gorge were studied in more detail using site occupancy models, relative abundance index, and other technologies and methods. The results show that The occupancy predicted by the model exceeds or approaches 0.5. The occupancy increases with greater altitude and with larger EVI values, while the detection rate increases with altitude only during spring and decreases with EVI values only in summer. The daily activity peaks for white-lipped deer were observed from 7:00 to 11:00 and 17:00 to 22:00, with annual activity peaks occurring from April to June and from September to November. From July to the following January, white-lipped deer mostly move in mixed-sex groups, while during the remainder of the year, they predominantly associate with individuals of the same sex. Climate, vegetation coverage, food resources, and human disturbance collectively influenced the behavior and habitat utilization of white-lipped deer. The foundational research conducted on white-lipped deer over the past two years is expected to enhance the basic understanding of white-lipped deer in the Qinghai-Tibet Plateau and contribute to future protection and management decisions.

Assessment of black and gold howler monkey (<i>Alouatta caraya</i>, Humboldt, 1812) populations in two new study sites in northeastern Argentina


 
 
 Alouatta caraya has the southernmost distribution of the howler monkeys. While information about most populations remains limited, the forests this species inhabits are being altered continuously. We present data about populations of A. caraya from two new study sites in northeastern Argentina: the “Laguna Oca” Biosphere Reserve (RLO) (26°14'S, 58°10'W), and the “Las Lomas” Private Reserve (RLL) (27°23'S, 58°22'W). We conducted censuses along roads within forest patches in both areas to find groups of A. caraya, counting all visible individuals, and classifying them by sex and age. We found only mixed sex groups in both areas, with a density of 1.12 individuals/ha in RLO and 2.05 individuals/ ha in RLL. At other study sites in Argentina, A. caraya population densities vary from 0.11 to 3.25 individuals/ha, where forest continuity may be important in determining densities. Maintaining long-term study sites of A. caraya across different habitats will allow comparative analyses to explore the underlying mechanisms of behavioral, ecological, and demographic variability.
 
 

Risky business: relating probability of direct contact to risk of chronic wasting disease

Chronic wasting disease (CWD) is a fatal, prion disease of cervids that was first detected in Alberta in 2005. Transmission of CWD by direct contact with infected individuals plays a major role in the early phases of an outbreak. Mule deer (Odocoileus hemionus) comprise 85% of CWD-infected animals in the province, and we investigated the seasonal effects of grouping patterns and landscape heterogeneity on direct, pair-wise contacts (distance of 3 m) within and between sex-specific (same or mixed sex) groups of mule deer in east-central Alberta. We determined seasonal contacts of mule deer based on proximity loggers that alter GPS schedules to record contact locations. We modeled the relative risk of contact between sex-specific dyads both within and between social groups based on landscape characteristics at the location of contact. We then assessed the support for 5 hypotheses that linked locations of seasonal contacts to occurrence of CWD on the landscape. Disease occurrence on the landscape was derived by comparing locations of CWD-infected and CWD-uninfected deer collected as part of the Alberta’s CWD hunter-harvest surveillance program. We found that contacts in winter occurred in areas where deer use was concentrated, whereas in summer, contact locations were less constrained in space where patterns of landscape characteristics at contact locations varied between sex-specific dyads. Contact probabilities of within and between-group male dyads in winter and between-group female dyads in summer were the best predictors of CWD risk in east-central Alberta. Our results relate habitat specific, social behaviors between conspecific mule deer to potential routes of CWD transmission and contribute to CWD research that guides management strategies for an emergent wildlife disease.

Crossbreeding to improve local chicken breeds: predicting growth performance of the crosses using the Gompertz model and estimated heterosis

The present study aims to validate the Gompertz model to predict the growth performance of chicken crosses according to growth curve parameters of the parental lines and the estimated heterosis for each curve parameter. A total of 252 one-day-old chicks of both sexes belonging to 6 genotypes, including Ross 308, Sassò (SA), Bionda Piemontese (BP), and Robusta Maculata (RM), and the crosses between these local breeds and SA (BP×SA and RM×SA) were randomly allocated in 18 pens (3 pens/genotype) in mixed-sex groups (14 animals/pen; 7 females and 7 males). The individual body weight (BW) of all birds was recorded once a week from hatching until slaughtering (81 d for Ross 308; 112 d for SA, 140 d for the other genotypes). We drew up our final dataset with 240 birds (40 birds/genotype; 20 females and 20 males). The growth curve of each genotype was described using the Gompertz model, and the heterosis for each growth curve parameter was calculated as the difference between F1 crosses and the average of parental breeds. The predicted growth curve parameters were evaluated by cross-validation. The Gompertz model accurately estimated the growth curves of all the genotypes (R2 > 0.90). Heterosis was significant for almost all growth curve parameters in both crosses (P < 0.05). Heterosis ranged from -13.0 to +11.5%, depending on parameters, but varied slightly between the crossbreeds (BP×SA and RM×SA). The predicted values of adult BW, weight at the inflection point, and maximum growth rate were overestimated for BP×SA and underestimated for RM×SA, with a mean error between observed and predicted values <│2.7│% for all the curve parameters. In conclusion, the growth performance of chicken crosses between local breeds and commercial strains can be accurately predicted with Gompertz parameters of the parental lines adjusting for heterosis.

An examination of the lyrical construction of Pop music

The current study examines the use of five different dimensions of language in popular music based on the sex of the performer. Theoretically grounded in both social cognitive theory and cultivation theory, the study analyzes popular music as a vehicle for enculturating gender norms within society. Sampling and analyzing over 700 popular songs, the lyrical construction of songs performed by females and males is compared. Similarities are found in many key areas, while differences are identified in the specific areas of power language and social language. Additional differences are identified and discussed when artists perform in mixed-sex groups. Based on the results, a discussion of the prominence of male writers and lack of female representation in the music industry is included.

Mixed-sex peer groups and violent delinquency: understanding the separate and combined influence of mixed-sex peer groups, sex, and romance on violent delinquency

ABSTRACT Prior studies suggest peer group sex composition is an important correlate of delinquency, but these studies often conflate the influence of other-sex peers with that of romantic and intimate partners. This research seeks to understand the influence of other-sex peers as separate from, but related to, romantic activity and sexual debut. I find that while sexual and romantic activity predict mixed-sex peer group (MSPG) membership, they do not fully explain the positive relationship between MSPG membership and violent delinquency. Guided by literature on gender socialization and the institutionalization of heteronormativity, I argue this result can be explained as the result of a heteronormative culture that problematizes platonic, other-sex interactions and forces adolescents to maintain other-sex friendships in non-surveilled spaces.