The biomechanical function of periodontal ligament fibres in orthodontic tooth movement

Orthodontic tooth movement occurs as a result of resorption and formation of the alveolar bone due to an applied load, but the stimulus responsible for triggering orthodontic tooth movement remains the subject of debate. It has been suggested that the periodontal ligament (PDL) plays a key role. However, the mechanical function of the PDL in orthodontic tooth movement is not well understood as most mechanical models of the PDL to date have ignored the fibrous structure of the PDL. In this study we use finite element (FE) analysis to investigate the strains in the alveolar bone due to occlusal and orthodontic loads when PDL is modelled as a fibrous structure as compared to modelling PDL as a layer of solid material. The results show that the tension-only nature of the fibres essentially suspends the tooth in the tooth socket and their inclusion in FE models makes a significant difference to both the magnitude and distribution of strains produced in the surrounding bone. The results indicate that the PDL fibres have a very important role in load transfer between the teeth and alveolar bone and should be considered in FE studies investigating the biomechanics of orthodontic tooth movement. © 2014 McCormack et al

Perceptions of the Freezing Response of Male and Female Rape Victims, and an examination of the Moderating Role of Rape Myth Beliefs

PurposeThe purpose of this study was to investigate whether indicating victims of sexual attacks actively resisted their attacker or froze during their assault affected perceptions of victim blame, perpetrator blame and seriousness of the crime. We also tested whether victim and perpetrator gender or participants’ rape myth endorsement moderated the outcomes.Design/methodology/approachThis study was a cross-sectional, vignette survey study with a 2 × 2 between-participants experimental design. Participants read a mock police report describing an alleged rape with a female or male victim who either resisted or froze, while perpetrator gender was adjusted heteronormatively.FindingsFreezing and male victims were blamed more than resisting and female victims. Perpetrators were blamed more when the victim resisted, but male and female perpetrators were blamed equally. Seriousness of the crime was higher for male perpetrators and when the victim resisted. Female, but not male, rape myth acceptance moderated the relationship between victim behaviour and outcome variables.Originality/valueThis study highlights the influence of expectations about victim behaviour on perceptions of rape victims and the pervasive influence of rape myths when evaluating female rape victims. The data is drawn from the German border region of the Netherlands, which is an especially valuable population given the evolving legal definitions of rape in both countries

Masticatory biomechanics in the rabbit : a multi-body dynamics analysis

Acknowledgement We thank Sue Taft (University of Hull) for the µCT-scanning of the rabbit specimen used in this study. We also thank Raphaël Cornette, Jacques Bonnin, Laurent Dufresne, and l'Amicale des Chasseurs Trappistes (ACT) for providing permission and helping us capture the rabbits used for the in vivo bite force measurements at la Réserve Naturelle Nationale de St Quentin en Yvelines, France.Peer reviewedPublisher PD

Innovative multi-material tool use in the pant-hoot display of a chimpanzee

‘Pant-hoot displays’ are a species-typical, multi-modal communicative behaviour in chimpanzees in which pant-hoot vocalisations are combined with varied behavioural displays. In both captivity and the wild, individuals commonly incorporate striking or throwing elements of their environment into these displays. In this case study, we present five videos of an unenculturated, captive, adult male chimpanzee combining a large rubber feeding tub with excelsior (wood wool) in a multi-step process, which was then integrated into the subject’s pant-hoot displays as a percussive tool or ‘instrument’. During the construction process, the subject demonstrated an understanding of the relevant properties of these materials, ‘repairing’ the tub to be a more functional drum when necessary. We supplement these videos with a survey of care staff from the study site for additional detail and context. Although care must be taken in generalising data from a single individual, the behaviour reported here hints at three intriguing features of chimpanzee communicative cognition: (1) it suggests a degree of voluntary control over vocal production, (2) it is a so-far unique example of compound tool innovation and use in communicative behaviour and (3) it may represent an example of forward planning in communicative behaviour. Each of these would represent hitherto undocumented dimensions of flexibility in chimpanzee communication, mapping fertile ground for future research

Costs and cost trends for forestry practices in the South

Cost estimates of practicing forestry in the South during 1986 and cost changes during the 1952-1986 period are presented in this report. Albert C. Worrell reported the original cost study in Forest Farmer in May 1953. His work was updated by James G. Yoho and Robert B. Fish in the November 1961 issue of Forest Farmer. Other revisions include James G. Yoho, George F . Dutrow, and James Moak (Forest Farmer, 1971); James Moak and Jim Kucera (Forest Farmer, 1975); James Moak, James Kucera, and W.F. Watson (Forest Farmer Manual, 1977); James Moak, W.F. Watson, and Paul Van Deusen (Forest Farmer Manual, 1980); James Moak, W.F. Watson, and Mark Watson (Forest Farmer Manual, 1983); and Thomas J. Straka and William F . Watson (Forest Farmer Manual, 1985). The present study is based on the results of a survey completed in 1986 and reports current costs for most forestry practices covered by previous surveys. It also provides tables with cost changes from 1952 to 1986 for\u27 specific commercial practices common in the South

It pays to know how your timber will be valued

You as a forest farmer can usually realize income from your timber investment in two ways. You can rent timberland for nontimber uses (usually hunting) , or you can lease or sell your interest in the timber. In most cases, greater returns result from selling timber outright

Primer on forestry investment

Most forest farmers know that growing timber is a good investment. Some forest farmers, however, and many new timberland investors may not fully understand the basic ingredients that make up a forestry investment. Like other ventures, forest farming involves costs and revenues, and rates of return can be calculated. These rates can be compared with interest rates for other investments, but forest farming is not exactly like your other investments. It has special qualities

How multiple interviews and interview framing influence the development and maintenance of rapport

Information obtained from investigative interviews is crucial for police to develop leads, advance investigations and make effective decisions. One well-endorsed approach for eliciting detailed and accurate information is building rapport between the interviewer and interviewee. While familiarity and communicative tone are predicted determinants of rapport, the effects of repeated exposure to an interviewer, as well as interview framing, on rapport has rarely been tested. In two simulated suspect interview experiments, we tested whether established rapport is maintained during a second interview with the same interviewer (Experiment 1) and how accusatory and humanitarian interview framings impact the development of rapport (Experiment 2). We also tested, across both experiments, whether nonverbal mimicry can be a proxy for measuring rapport. We found evidence suggesting that rapport, once established, is carried over to subsequent meetings, and that it is possible to build rapport even when it was poorly established in the initial interview. We also found that an accusatory interview framing was associated with lower rapport than a humanitarian interview framing, and that interview framing affected nonverbal mimicry between interviewer and interviewee. Contrary to our expectations, mimicry did not correlate with an existing measure of rapport

Chimpanzees prioritise social information over pre-existing behaviours in a group context but not in dyads

Funding: John Templeton Foundation (US) (40128).How animal communities arrive at homogeneous behavioural preferences is a central question for studies of cultural evolution. Here, we investigated whether chimpanzees (Pan troglodytes) would relinquish a pre-existing behaviour to adopt an alternative demonstrated by an overwhelming majority of group mates; in other words, whether chimpanzees behave in a conformist manner. In each of five groups of chimpanzees (N = 37), one individual was trained on one method of opening a two-action puzzle box to obtain food, while the remaining individuals learned the alternative method. Over 5 h of open access to the apparatus in a group context, it was found that 4/5 ‘minority’ individuals explored the majority method and three of these used this new method in the majority of trials. Those that switched did so after observing only a small subset of their group, thereby not matching conventional definitions of conformity. In a further ‘Dyad’ condition, six pairs of chimpanzees were trained on alternative methods and then given access to the task together. Only one of these individuals ever switched method. The number of observations that individuals in the minority and Dyad individuals made of their untrained method was not found to influence whether or not they themselves switched to use it. In a final ‘Asocial’ condition, individuals (N = 10) did not receive social information and did not deviate from their first-learned method. We argue that these results demonstrate an important influence of social context upon prioritisation of social information over pre-existing methods, which can result in group homogeneity of behaviour.Publisher PDFPeer reviewe