scholarly journals Adolescent school injuries and classroom sex compositions in German secondary schools

2021 ◽  
Author(s):  
Andreas Filser ◽  
Sven Stadtmüller ◽  
Robert Lipp ◽  
Richard Preetz
Keyword(s):  
Sex Ratio ◽  
Secondary Schools ◽  
Risk Taking ◽  
Regression Models ◽  
Sex Ratios ◽  
Peer Groups ◽  
Positive Association ◽  
Logistic Regression Models ◽  
Adolescent Students ◽  
Males And Females

School injuries are an important adolescent health problem. Previous research suggests that relevant risk behaviors for school injuries, risk-taking and aggression, are highly susceptible to peer effects. Specifically, evidence suggests that the ratio of males and females in peer groups (sex ratio) affects individuals’ propensity for aggression and risk-taking. However, research so far has ignored potential associations of classroom sex ratios with adolescent school injury risks. In this paper, we investigate the association of classroom sex compositions with adolescent school injuries in a longitudinal survey dataset containing 13,131 observations from 9,204 adolescent students (ages 13-16) from secondary schools in Germany. The data also allow us to identify injuries that were due to aggressive behavior and analyze these injuries in detail. Results from multilevel logistic regression models reveal that adolescent students’ risk for school injuries is significantly and positively associated with male-skewed classroom sex ratios. Moreover, we find an even stronger positive association between male-dominated classrooms and aggression-injury risks. Finally, we find that both boys’ and girls’ injury risks equally increase with a higher proportion of males in their classroom. We discuss the implications of our findings with regard to the sex ratio literature and potential interventions.

scholarly journals Adolescent school injuries and classroom sex compositions in German secondary schools

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Andreas Filser ◽  
Sven Stadtmüller ◽  
Robert Lipp ◽  
Richard Preetz
Keyword(s):  
Sex Ratio ◽  
Secondary Schools ◽  
Risk Taking ◽  
Sex Ratios ◽  
Peer Groups ◽  
Positive Association ◽  
Male Students ◽  
Logistic Regression Models ◽  
Adolescent Students ◽  
Intervention Planning

Abstract Background School injuries are an important adolescent health problem. Previous research suggests that relevant risk behaviors for school injuries, risk-taking and aggression, are highly susceptible to peer effects. Specifically, evidence suggests that the ratio of men and women in peer groups (sex ratio) affects individuals’ propensity for aggression and risk-taking. However, potential associations of classroom sex ratios with adolescent school injury risks have not been studied so far. The purpose of this paper is to investigate the association of classroom sex compositions with adolescent school injuries. Methods We investigate the association of classroom sex ratios with school injuries in a longitudinal survey dataset containing 13,131 observations from 9,204 adolescent students (ages 13-16) from secondary schools in Germany. The data also allow us to identify injuries due to aggressive behavior and analyze these injuries in detail. We use multilevel logistic regression models to analyze risks of both overall and aggression-related school injuries. Results Adolescent students’ risk for school injuries is significantly and positively associated with male-skewed classroom sex ratios (OR = 1.012, p=0.012). Specifically, the risk of sustaining a school injury increases by 33.5 percent when moving from the 10th to the 90th classroom sex ratio percentile. Moreover, we find an even stronger positive association between male-dominated classrooms and aggression-related injury risks (OR = 1.022, p=0.010). Compared to classroom sex ratios at the 10th percentile, the risk of an aggression-related injury is 78 percent higher in classrooms with a sex ratio at the 90th percentile. Finally, we find that both boys’ and girls’ injury risks equally increase with a higher proportion of male students in their classroom. Conclusions Our findings indicate that sex composition of classrooms is an important contextual factor for adolescent school injuries, in particular school injuries resulting from aggression. These findings illustrate the need to integrate a contextual perspective on school injuries among adolescent students both into research and into intervention planning.

A new male-killing parasitism:Spiroplasmabacteria infect the ladybird beetleAnisosticta novemdecimpunctata(Coleoptera: Coccinellidae)

Parasitology ◽  
2006 ◽  
Vol 132 (6) ◽  
pp. 757-765 ◽  
Author(s):  
M. C. TINSLEY ◽  
M. E. N. MAJERUS
Keyword(s):  
Phylogenetic Analysis ◽  
Sex Ratio ◽  
High Efficiency ◽  
Sex Ratios ◽  
Egg Hatch ◽  
Hatch Rate ◽  
Male Killing ◽  
Offspring Sex ◽  
Novel Host ◽  
Males And Females

Whilst most animals invest equally in males and females when they reproduce, a variety of vertically transmitted parasites has evolved the ability to distort the offspring sex ratios of their hosts. One such group of parasites are male-killing bacteria. Here we report the discovery of females of the ladybirdAnisosticta novemdecimpunctatathat produced highly female-biased offspring sex ratios associated with a 50% reduction in egg hatch rate. This trait was maternally transmitted with high efficiency, was antibiotic sensitive and was infectious following experimental haemolymph injection. We identified the cause as a male-killingSpiroplasmabacterium and phylogenetic analysis of rDNA revealed that it belongs to theSpiroplasma ixodetisclade in which other sex ratio distorters lie. We tested the potential for interspecific horizontal transfer by injection from an infectedA. novemdecimpunctataline into uninfected individuals of the two-spot ladybirdAdalia bipunctata. In this novel host, the bacterium was able to establish infection, transmit vertically and kill male embryos.

scholarly journals Analysis of the sex ratio in Bradysia matogrossensis (Diptera, Sciaridae)

2000 ◽  
Vol 23 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Lincoln S. Rocha ◽  
André Luiz P. Perondini
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
X Chromosome ◽  
Control Mechanism ◽  
Sex Ratios ◽  
Laboratory Strain ◽  
Chromosome Elimination ◽  
Common Control ◽  
Males And Females ◽  
Successive Generations

In sciarid flies, the control of sex determination and of the progeny sex ratio is exercised by the parental females, and is based on differential X-chromosome elimination in the initial stages of embryogenesis. In some species, the females produce unisexual progenies (monogenic females) while in others, the progenies consist of males and females (digenic females). The sex ratio of bisexual progenies is variable, and departs considerably from 1:1. Bradysia matogrossensis shows both monogenic and digenic reproduction. In a recently established laboratory strain of this species, 15% of the females were digenic, 10% produced only females, 13% produced only males, and 62% produced progenies with one predominant sex (33% predominantly of female and 29% predominantly male progenies). These progeny sex ratios were maintained in successive generations. Females from female-skewed progenies yielded female- and male-producing daughters in a 1:1 ratio. In contrast, daughters of females from male-skewed progenies produce bisexual or male-skewed progenies. The X-chromosome of B. matogrossensis shows no inversion or other gross aberration. These results suggest that the control of the progeny sex ratio (or differential X-chromosome elimination) involves more than one locus or, at least, more than one pair of alleles. The data also suggest that, in sciarid flies, monogeny and digeny may share a common control mechanism.

scholarly journals The association of diabetes and BMI among Melanesian and Indian Fijians aged ≥ 40 years

2011 ◽  
Vol 105 (10) ◽  
pp. 1539-1545 ◽  
Author(s):  
Garry Brian ◽  
Jacqueline Ramke ◽  
Andrew Page ◽  
Louise Maher ◽  
John Szetu ◽  
...  
Keyword(s):  
Regression Models ◽  
Medical Practitioner ◽  
Population Based ◽  
Common Environment ◽  
Logistic Regression Models ◽  
Previous Diagnosis ◽  
Males And Females ◽  
Adjusted Logistic Regression ◽  
Hb Concentration ◽  
Population Based Survey

The present study examines the association of diabetes with BMI (kg/m2) in Asian-Indian and Melanesian Fijian populations sharing a common environment. A population-based survey was used to investigate the risk of diabetes (defined by glycosylated Hb concentration ≥ 6·5 % among participants who denied previous diagnosis of the disease by a medical practitioner) by sex, ethnicity and strata of BMI in a series of age-adjusted logistic regression models. Ethnicity and BMI interactions were compared using WHO and empirically derived BMI cut-off points. Indians had a greater risk (BMI and age adjusted) of undetected diabetes than Melanesians in both males (OR 2·99, 95 % CI 1·73, 5·17; P < 0·001) and females (OR 2·26, 95 % CI 1·56, 3·28; P < 0·001). BMI ≥ 25 to < 30 and ≥ 30 kg/m2 conferred a higher risk of diabetes compared with a BMI ≥ 18·5 to < 25 kg/m2. Risk was higher for males with a BMI ≥ 25 to < 30 kg/m2 (OR 2·35, 95 % CI 1·24, 4·46; P = 0·007) and BMI ≥ 30 kg/m2 (OR 6·08, 95 % CI 3·06, 12·07; P < 0·001) than for females with the same BMI (OR 1·85, 95 % CI 1·11, 3·08; P = 0·027 and OR 2·10, 95 % CI 1·28, 3·44; P = 0·002, respectively). However, the threshold that appeared to differentiate higher risk varied by ethnicity and sex. For Melanesians, BMI thresholds suggested were 25 kg/m2 for males and 32 kg/m2 for females. For Indo-Fijians, these were 24 and 22 kg/m2 for males and females, respectively. Disaggregating by ethnicity and sex, and applying specific evidence-based thresholds, may render BMI a more discriminating tool for assessing the risk of developing diabetes among Fiji adults.

scholarly journals Sex ratio distortion in bovine sperm correlates to recombination in the pseudoautosomal region

2000 ◽  
Vol 75 (1) ◽  
pp. 53-59 ◽  
Author(s):  
JOANNA SZYDA ◽  
HENNER SIMIANER ◽  
SIGBJØRN LIEN
Keyword(s):  
Sex Ratio ◽  
Recombination Rate ◽  
Regression Models ◽  
Segregation Ratio ◽  
Pseudoautosomal Region ◽  
Logistic Regression Models ◽  
Bovine Sperm ◽  
Y Chromosomes ◽  
Ratio Distortion ◽  
Sex Ratio Distortion

A total of 2122 single sperm from 35 bulls belonging to six different paternal half-sib groups were analysed with respect to two markers in the bovine pseudoautosomal region (PAR) and sex- specific loci on the X and Y chromosomes, respectively. A segregation ratio significantly different from 1[ratio ]1 was observed in a test over all families, with a higher proportion of X-bearing gametes (53·5%). The analysis of recombination conducted separately for X- and Y-bearing sperm showed that X-bearing sperm cells possess highly significant individual and between-family variability in recombination rate, whereas Y-bearing sperm show linkage homogeneity. To test whether the two phenomena are related, different logistic regression models were fitted to the data. The results show that sex ratio significantly correlates with changes in recombination rate among X-bearing but not among Y-bearing sperm. Different hypotheses to explain these observations are discussed.

scholarly journals Anemia and iron deficiency in Mexican elderly population. Results from the Ensanut 2012

2015 ◽  
Vol 57 (5) ◽  
pp. 394 ◽  
Author(s):  
Alejandra Contreras-Manzano ◽  
Vanessa De la Cruz ◽  
Salvador Villalpando ◽  
Rosario Rebollar ◽  
Teresa Shamah-Levy
Keyword(s):  
Iron Deficiency ◽  
Regression Models ◽  
Elderly Population ◽  
The Elderly ◽  
Serum Concentrations ◽  
Nutrition Survey ◽  
Logistic Regression Models ◽  
Health And Nutrition ◽  
Males And Females ◽  
Prevalence Of Anemia

Objective. To describe de prevalence of iron deficiency (ID) and anemia in a sample of Mexican elderly population from the National Health and Nutrition Survey (Ensanut) 2012. Materials and methods. 1 920 subjects ≥60 years of age were included. Hemoglobin, serum concentrations of ferritin and CRP were measured. The risk for ID and anemia adjusted for potential confounders was assessed in logistic regression models. Results. The overall prevalence of anemia was 13.9%, 15.2% in males and 12.8% females. For ID,overall it was 4.2%, males 4.0% and females 4.3%. The greatest prevalence of ID was found in males and females over 80 years old (6.9 and 7.0%, respectively). ID was present in 1.5 of 10 Mexican elders with anemia. Conclusion. The prevalence of anemia was high in the elderly, however the prevalence of ID was low; there is a need to further investigate the causes of anemia in this age group.

Sex-Ratios and Related Characteristics in Spinifex sericeus (Poaceae)

1990 ◽  
Vol 38 (2) ◽  
pp. 153 ◽  
Author(s):  
KM Maze ◽  
RDB Whalley
Keyword(s):  
Sex Ratio ◽  
New Caledonia ◽  
New South ◽  
Sand Dunes ◽  
Sex Ratios ◽  
Experimental Period ◽  
North Coast ◽  
Male Bias ◽  
South Wales ◽  
Males And Females

Spinifex sericeus R.Br. is a dioecious, stoloniferous grass which occurs on sand dunes around much of the south-eastern coastline of Australia, New Zealand and New Caledonia. Sex ratios of ramets of S. sericeus and some associated characteristics were studied on the mid-north coast of New South Wales. Generally there was a male bias in the observed ramet sex ratio, although the extent of this bias varied with the beach investigated, the position in the dunes and the time of sampling. Male inflorescences matured and died more rapidly than females, and hence the observed male bias was greatest at the beginning of the flowering period. Male ramets were found to have more sexual tillers per clump than female ramets. The genet sex ratio was estimated from plants grown from seed and separated from each other throughout the experimental period. Males and females were found to be equal in number, although this equality may not be a true reflection of the genet sex ratio in the field.

Sex ratios and survival in fluctuating populations of the deer mouse, Peromyscus mamculatus borealis

1970 ◽  
Vol 48 (4) ◽  
pp. 809-811 ◽  
Author(s):  
Raymond P. Canham
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Deer Mouse ◽  
Sex Ratios ◽  
Natural Populations ◽  
In Captivity ◽  
Males And Females ◽  
Young Of The Year ◽  
Fluctuating Populations ◽  
Number Of Males

In litters of the deer mouse, Peromyscus mamculatus borealis, born in captivity there was a significantly greater number of males than females. In natural populations of the same subspecies, an excess of males caused the sex ratio in captured young of the year to differ significantly from 1:1 only in those summers in which population density increased considerably. The sex ratio did not change appreciably during a winter in which density remained stable, but in winters of low survival the proportion of males declined. A difference between males and females in the amplitude of the fluctuations in postnatal survival thus appeared responsible for variations in the sex ratio.

scholarly journals Menarche increases relapse risk in pediatric multiple sclerosis

2015 ◽  
Vol 22 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Sabeen Lulu ◽  
Jennifer Graves ◽  
Emmanuelle Waubant
Keyword(s):  
Multiple Sclerosis ◽  
Sex Ratio ◽  
Clinical Features ◽  
Regression Models ◽  
Disease Onset ◽  
Disease Course ◽  
Pediatric Multiple Sclerosis ◽  
Males And Females ◽  
Age Of Menarche

Background: Multiple sclerosis (MS) predominantly affects women with a sex ratio of 3:1 in contrast with a 1:1 sex ratio seen in pre-pubertal onset. Thus, puberty may influence MS risk differentially in males and females. How puberty may be associated with MS clinical features and disease course remains unknown. Objective: The objective of this paper is to determine the association of menarche with disease course in girls with MS. Methods: This is a longitudinal retrospective study from the UCSF Regional Pediatric MS Center database. We categorized patients by time of disease onset: pre-menarche, peri-menarche and post-menarche. Poisson regression models were used for within-subject relapse analyses offset by follow-up time. Results: Seventy-six girls were included (pre-menarche onset = 17; peri-menarche onset = 9; post-menarche onset = 50). Age of menarche was similar in all groups (Kruskal-Wallis p = 0.19). Relapse rate was the same in all three groups during the first two years of follow-up. In girls with follow-up overlapping at least two time periods, within-subject analyses showed increased relapses during the peri-menarche compared to post-menarche period (adjusted IRR = 8.5, 95% CI 2.5–28.7, p = 0.001). Conclusion: Pubertal status may influence MS course at least in female patients. Understanding how puberty influences MS clinical features may offer new insights into important factors regulating disease processes.

scholarly journals Estimating adult sex ratios in nature

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160313 ◽  
Author(s):  
Sergio Ancona ◽  
Francisco V. Dénes ◽  
Oliver Krüger ◽  
Tamás Székely ◽  
Steven R. Beissinger
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Evolutionary Biology ◽  
Adult Population ◽  
Sex Ratios ◽  
Estimation Methods ◽  
Spatial And Temporal Variation ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effects of spatial and temporal variation in the numbers of males and females, and detection/capture probabilities that differ between the sexes. Here, we critically evaluate methods for estimating ASR in wild animal populations, reviewing how recent statistical advances can be applied to handle some of these challenges. We review methods that directly account for detection differences between the sexes using counts of unmarked individuals (observed, trapped or killed) and counts of marked individuals using mark–recapture models. We review a third class of methods that do not directly sample the number of males and females, but instead estimate the sex ratio indirectly using relationships that emerge from demographic measures, such as survival, age structure, reproduction and assumed dynamics. We recommend that detection-based methods be used for estimating ASR in most situations, and point out that studies are needed that compare different ASR estimation methods and control for sex differences in dispersal. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

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