scholarly journals Bite force estimates in juvenile Tyrannosaurus rex based on simulated puncture marks

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11450
Author(s):  
Joseph E. Peterson ◽  
Z. Jack Tseng ◽  
Shannon Brink
Keyword(s):  
Cortical Bone ◽  
Late Cretaceous ◽  
Linear Models ◽  
Mechanical Tests ◽  
Bite Force ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Ontogenetic Changes ◽  
Bite Marks

Background Bite marks attributed to adult Tyrannosaurus rex have been subject to numerous studies. However, few bite marks attributed to T. rex have been traced to juveniles, leaving considerable gaps in understanding ontogenetic changes in bite mechanics and force, and the paleoecological role of juvenile tyrannosaurs in the late Cretaceous. Methods Here we present bite force estimates for a juvenile Tyrannosaurus rex based on mechanical tests designed to replicate bite marks previously attributed to a T. rex of approximately 13 years old. A maxillary tooth of the juvenile Tyrannosaurus specimen BMR P2002.4.1 was digitized, replicated in dental grade cobalt chromium alloy, and mounted to an electromechanical testing system. The tooth was then pressed into bovine long bones in various locations with differing cortical bone thicknesses at varying speeds for a total of 17 trials. Forces required to replicate punctures were recorded and puncture dimensions were measured. Results Our experimentally derived linear models suggest bite forces up to 5,641.19 N from cortical bone thickness estimated from puncture marks on an Edmontosaurus and a juvenile Tyrannosaurus. These findings are slightly higher than previously estimated bite forces for a juvenile Tyrannosaurus rex of approximately the same size as BMR P2002.4.1 but fall within the expected range when compared to estimates of adult T. rex. Discussion The results of this study offer further insight into the role of juvenile tyrannosaurs in late Cretaceous ecosystems. Furthermore, we discuss the implications for feeding mechanisms, feeding behaviors, and ontogenetic niche partitioning.

scholarly journals Wider-community Segregation and the Effect of Neighbourhood Ethnic Diversity on Social Capital: An Investigation into Intra-Neighbourhood Trust in Great Britain and London

Sociology ◽  
2016 ◽  
Vol 51 (5) ◽  
pp. 1011-1033 ◽  
Author(s):  
James Laurence
Keyword(s):  
Social Capital ◽  
Great Britain ◽  
Ethnic Diversity ◽  
Linear Models ◽  
Critical Role ◽  
Hierarchical Linear Models ◽  
Negatively Associated ◽  
Community Segregation ◽  
Do So

Extensive research has demonstrated that neighbourhood ethnic diversity is negatively associated with intra-neighbourhood social capital. This study explores the role of segregation and integration in this relationship. To do so it applies three-level hierarchical linear models to two sets of data from across Great Britain and within London, and examines how segregation across the wider-community in which a neighbourhood is nested impacts trust amongst neighbours. This study replicates the increasingly ubiquitous finding that neighbourhood diversity is negatively associated with neighbour-trust. However, we demonstrate that this relationship is highly dependent on the level of segregation across the wider-community in which a neighbourhood is nested. Increasing neighbourhood diversity only negatively impacts neighbour-trust when nested in more segregated wider-communities. Individuals living in diverse neighbourhoods nested within integrated wider-communities experience no trust-penalty. These findings show that segregation plays a critical role in the neighbourhood diversity/trust relationship, and that its absence from the literature biases our understanding of how ethnic diversity affects social cohesion.

scholarly journals Chromosome Instability, Aging and Brain Diseases

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1256
Author(s):  
Ivan Y. Iourov ◽  
Yuri B. Yurov ◽  
Svetlana G. Vorsanova ◽  
Sergei I. Kutsev
Keyword(s):  
Brain Aging ◽  
Chromosome Instability ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Accelerated Aging ◽  
Brain Diseases ◽  
Aging Brain ◽  
Ontogenetic Changes ◽  
Health And Disease

Chromosome instability (CIN) has been repeatedly associated with aging and progeroid phenotypes. Moreover, brain-specific CIN seems to be an important element of pathogenic cascades leading to neurodegeneration in late adulthood. Alternatively, CIN and aneuploidy (chromosomal loss/gain) syndromes exhibit accelerated aging phenotypes. Molecularly, cellular senescence, which seems to be mediated by CIN and aneuploidy, is likely to contribute to brain aging in health and disease. However, there is no consensus about the occurrence of CIN in the aging brain. As a result, the role of CIN/somatic aneuploidy in normal and pathological brain aging is a matter of debate. Still, taking into account the effects of CIN on cellular homeostasis, the possibility of involvement in brain aging is highly likely. More importantly, the CIN contribution to neuronal cell death may be responsible for neurodegeneration and the aging-related deterioration of the brain. The loss of CIN-affected neurons probably underlies the contradiction between reports addressing ontogenetic changes of karyotypes within the aged brain. In future studies, the combination of single-cell visualization and whole-genome techniques with systems biology methods would certainly define the intrinsic role of CIN in the aging of the normal and diseased brain.

scholarly journals Relationship between Cycling Infrastructure and Transportation Cycling in a Small Urban Area

2021 ◽  
Vol 1 (1) ◽  
pp. 99-112
Author(s):  
Richard Larouche ◽  
Nimesh Patel ◽  
Jennifer L. Copeland
Keyword(s):  
Generalized Linear Models ◽  
Qualitative Data ◽  
Linear Models ◽  
The Other ◽  
Small City ◽  
The Road ◽  
The Past ◽  
Low Prevalence ◽  
The Relationship

The role of infrastructure in encouraging transportation cycling in smaller cities with a low prevalence of cycling remains unclear. To investigate the relationship between the presence of infrastructure and transportation cycling in a small city (Lethbridge, AB, Canada), we interviewed 246 adults along a recently-constructed bicycle boulevard and two comparison streets with no recent changes in cycling infrastructure. One comparison street had a separate multi-use path and the other had no cycling infrastructure. Questions addressed time spent cycling in the past week and 2 years prior and potential socio-demographic and psychosocial correlates of cycling, including safety concerns. Finally, we asked participants what could be done to make cycling safer and more attractive. We examined predictors of cycling using gender-stratified generalized linear models. Women interviewed along the street with a separate path reported cycling more than women on the other streets. A more favorable attitude towards cycling and greater habit strength were associated with more cycling in both men and women. Qualitative data revealed generally positive views about the bicycle boulevard, a need for education about sharing the road and for better cycling infrastructure in general. Our results suggest that, even in smaller cities, cycling infrastructure may encourage cycling, especially among women.

Closing Achievement Gaps: Examining the Roles of School Background and Process

2021 ◽  
pp. 001312452198944
Author(s):  
Huang Wu ◽  
Jianping Shen ◽  
Jessaca Spybrook ◽  
Xingyuan Gao
Keyword(s):  
Achievement Gap ◽  
Teacher Collaboration ◽  
White Students ◽  
Science Achievement ◽  
Linear Models ◽  
Achievement Gaps ◽  
School Level ◽  
Academic Learning ◽  
Closing Achievement Gaps

The purpose of this study was to examine the role of school background and school process in closing achievement gaps between White and non-White students in science. To answer the research questions, a series of two-level hierarchical linear models (HLM) was performed on the fourth-grade U.S. portion of the 2015 Trends in International Mathematics and Science Study (TIMSS) data. Results indicate that (a) the science achievement gap between White and non-White students is 0.21 standard deviation, holding student and school background constant; (b) the science achievement gap varies across schools; (c) none of the school background variables are associated with the achievement gap in a school; and (d) school emphasis on student academic learning is not only associated with higher school-level science achievement, but also with a narrower science achievement gap between White and non-White students. However, teacher collaboration is not associated with school-level science achievement but is associated with a larger achievement gap. Implications, limitations, and recommendations for further research are discussed.

Life Course Socioeconomic Position, Intergenerational Social Mobility, and Hypertension Incidence in ELSA-Brasil

2021 ◽  
Author(s):  
José Aparecido Soares Lopes ◽  
Luana Giatti ◽  
Rosane Harter Griep ◽  
Antonio Alberto da Silva Lopes ◽  
Sheila Maria Alvim Matos ◽  
...  
Keyword(s):  
Life Course ◽  
Social Mobility ◽  
Socioeconomic Position ◽  
Linear Models ◽  
Sociodemographic Factors ◽  
Incidence Rates ◽  
Explanatory Variables ◽  
Rate Ratios

Abstract Background Life course epidemiology is a powerful framework to unravel the role of socioeconomic position (SEP) disparities in hypertension (HTN). This study investigated whether life course SEP is associated with HTN incidence. Specifically, to test whether cumulative low SEP throughout life and unfavorable intergenerational social mobility increased HTN incidence. METHODS Longitudinal analysis of 8,754 ELSA-Brasil participants without HTN or cardiovascular in visit 1 (2008–2010). The response variable was the incidence of HTN between visits 1 and 2 (2012–2014). The explanatory variables were childhood, youth, and adulthood SEP, cumulative low SEP, and intergenerational social mobility. Associations were estimated by incidence rate ratios (IRRs) obtained by generalized linear models, with Poisson distribution and logarithmic link function, after adjustment for sociodemographic, behavioral, and health factors. RESULTS The incidence of HTN was 43.2/1,000 person-years, being higher in males, elderly (70–74 years), self-declared black, and low SEP individuals. After considering sociodemographic factors, low SEP in childhood, youth, and adulthood remained statistically associated with increased HTN incidence. Individuals in the third (IRR: 1.26; 95% confidence interval (CI): 1.11–1.44) and fourth top quartiles (IRR: 1.29; 95% CI: 1.11–1.49) of cumulative low SEP, vs. first, as well as those with low stable intergenerational trajectory (IRR: 1.29; 95% CI: 1.16–1.43), vs. high stable, also had increased HTN incidence rates. Conclusions Socioeconomic disparities at all phases of the life cycle appear to raise HTN incidence rates, being the individuals with greater accumulation of exposure to low SEP and with more unfavorable intergenerational mobility at greatest risk, even in a short follow-up time.

scholarly journals The Role of Organic Matter on Uranium Precipitation in Zoovch Ovoo, Mongolia

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 310 ◽  
Author(s):  
Dimitrios Rallakis ◽  
Raymond Michels ◽  
Marc Brouand ◽  
Olivier Parize ◽  
Michel Cathelineau
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Late Cretaceous ◽  
Uranium Deposit ◽  
Vitrinite Reflectance ◽  
Driven Systems ◽  
Sem Observation ◽  
Organic Matter Type ◽  
Clay Layers

The Zoovch Ovoo uranium deposit is located in East Gobi Basin in Mongolia. It is hosted in the Sainshand Formation, a Late Cretaceous siliciclastic reservoir, in the lower part of the post-rift infilling of the Mesozoic East Gobi Basin. The Sainshand Formation corresponds to poorly consolidated medium-grained sandy intervals and clay layers deposited in fluvial-lacustrine settings. The uranium deposit is confined within a 60- to 80-m-thick siliciclastic reservoir inside aquifer driven systems, assimilated to roll-fronts. As assessed by vitrinite reflectance (%Rr < 0.4) and molecular geochemistry, the formation has never experienced significant thermal maturation. Detrital organic matter (type III and IV kerogens) is abundant in the Zoovch Ovoo depocenter. In this framework, uranium occurs as: (i) U-rich macerals without any distinguishable U-phase under SEM observation, containing up to 40 wt % U; (ii) U expressed as UO2 at the rims of large (several millimeters) macerals and (iii) U oxides partially to entirely replacing macerals, while preserving the inherited plant texture. Thus, uranium is accumulated gradually in the macerals through an organic carbon–uranium epigenization process, in respect to the maceral’s chemistry and permeability. Most macerals are rich in S and, to a lesser extent, in Fe. Frequently, Fe and S contents do not fit the stoichiometry of pyrite, although pyrite also occurs as small inclusions within the macerals. The organic matter appears thus as a major redox trap for uranium in this kind of geological setting.

scholarly journals Delivery of paclitaxel from cobalt–chromium alloy surfaces without polymeric carriers

Biomaterials ◽  
2010 ◽  
Vol 31 (20) ◽  
pp. 5372-5384 ◽  
Author(s):  
Gopinath Mani ◽  
Celia E. Macias ◽  
Marc D. Feldman ◽  
Denes Marton ◽  
Sunho Oh ◽  
...  
Keyword(s):  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Polymeric Carriers ◽  
Cobalt Chromium Alloy

scholarly journals The role of cortical bone and its microstructure in bone strength

2006 ◽  
Vol 35 (suppl_2) ◽  
pp. ii27-ii31 ◽  
Author(s):  
Peter Augat ◽  
Sandra Schorlemmer
Keyword(s):  
Cortical Bone ◽  
Bone Strength
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