Can human maxillary premolar crown dimensions discriminate between males and females?

Studies showed that odontometry can be used to analyse the influence of sexual dimorphism on the size of the teeth in specific ancestries. The aim of this study was to explore the bucco-lingual dimensions expressed as a ratio of human maxillary premolar crowns in males and females from polled ancestries. ethnicities If this measurement could discriminate sex, it would have application in forensic cases, mass disasters and archaeology where the number of mingled human remains is high and the ancestry ethnicity is unknown or multiple; Moreover, methodologies applied on radiographs or biochemical analysis in the laboratory is not always possible. The sample studied consisted of unworn premolars from 51 skeletal remains, 19 females and 32 males of known sex from collections: the Hunterian Museum, Royal College of Surgeons, England and the Natural History Museum, London and 100 archived orthodontic plaster casts of young adult dental patients (50 females and 50 males) of Royal London Hospital. Digital photographs were taken parallel to the occlusal surface and intercuspal distance and maximum bucco-lingual distance were captured using ImageJ 1.47v (U. S. National Institutes of Health, Maryland, USA), and the ratio of both distances calculated. Results were compared using a t-test and showed that for both upper premolars, the overall ratio was greater in males than females; however this was not significantly different to zero. The overall ratio for first premolar (P1) was less than second premolar (P2) in males and females. These findings show that maxillary premolar, measured in this way, are not significantly different and cannot discriminate between the sexes in this sample of different ancestries

Fear appeals prior to a high-stakes examination can have a positive or negative impact on engagement depending on how the message is appraised

Previous studies have shown that teachers may use messages that focus on the importance of avoiding failure (fear appeals) prior to high-stakes examinations as a motivational tactic. The aim of this study was to examine whether fear appeals, and their appraisal as challenging or threatening, impacted on student engagement. Data were collected from 1373 students, clustered in 46 classes, and 81 teachers responsible for instruction in those classes, prior to a high-stakes mathematics secondary school exit examination. Data were analyzed in a multilevel structural equation model. The appraisal of fear appeals as challenging leads to greater student engagement and as threatening to lower student engagement. The impact of fear appeals on engagement was mediated by challenge and threat appraisals. The effectiveness of fear appeals as a motivational strategy depends on how they are interpreted by students

The timing of mandibular tooth formation in two African groups

Background: Ethnic differences in the timing of human tooth development are unclear. Aim: To describe similarities and differences in the timing of tooth formation in two groups of Sudanese children and young adults. Subjects and methods: The sample consisted of healthy individuals from Khartoum, Sudan, aged 2–23 years. The Northern group was of Arab origin (848 males, 802 females) and the Western group was of African origin (846 males, 402 females). Each mandibular left permanent tooth from first incisor to third molar was assessed from dental radiographs into one of 15 development stages. Mean ages at entry for 306 tooth stages were calculated using probit regression in males/females in each group and compared using a t-test. Results: Mean ages were not significantly different in most tooth stage comparisons between ethnic groups for both males (61/75) and females (56/76), despite a tendency of earlier mean ages in the Western group. Mean ages for most tooth stage comparisons between males and females (137/155) were not significantly different within ethnic groups suggesting low sexual dimorphism. Conclusion: The mean ages of most mandibular tooth formation stages were generally not significantly different between ethnic groups or between males and females in this study

Educating Young Adults in the Conejo Valley to Choose a Godly Spouse

Problem Divorce rates and marital satisfaction rates are similar in both Christian and non-Christian young adults. Yet increases in church attendance, religious commitment and spirituality have been shown to make significant differences in divorce and marital satisfaction rates. However, many young adults have no framework to understand how to choose a potential spouse, or what factors or characteristics are most important in making such a choice. Almost all premarital education is aimed at young adults who have already chosen their spouse, but have no education aimed at understanding what matters most in making this choice. Method A weekend seminar was designed and presented at The Place Adventist Fellowship the weekend of May 19, 2017, that sought to educate young adults on the characteristics most important in a prospective spouse. Thirteen young adults participated in the entire seminar receiving education on developing a biblical framework for marriage. The participants were asked to complete two separate pre-surveys exploring their beliefs regarding characteristics deemed most important in a potential spouse and two identical post-surveys to measure if their beliefs were influenced by the seminar. The results were evaluated using analysis of the numerical data, observations and written reflections by the participants. Results The seminar and data revealed a group of 13 young adults who had received no formal premarital education. They were enthusiastic about learning through biblical education and contemporary research how to best develop a framework for understanding the characteristics most important in a potential spouse, and for themselves as a potential spouse. Throughout the seminar, participants expressed a desire for greater education in this regard. The data indicated they were receptive to the biblical characteristics of “hot, holy and healthy” and the seminar was meaningful in enabling the participants to freely discern what characteristics were truly important to them. Conclusion Based on the participants’ reflections, the seminar experience and the data from the pre- and post-surveys, the seminar did appear to have spiritual and educational value to them. Consequently, further premarital education regarding the characteristics most important in a potential spouse is merited and recommended

The ecological life history of the Cape Bulbul

The study of the ecological life history of the Cape Bulbul Pycnonotus capensis was carried out in 20 hectares of coastal dune forest near Port Elizabeth, South Africa. Results from four years 1959 to 1962 are given in detail and only the number of breeding pairs present in 1958 have been used from observations that year. The Cape Bulbul is one of three closely related species of a predominantly tropical family. Intra specific breeding is rare and occurs only where man has altered the habitat. Distribution has altered slightly in 150 years where colonisation has occurred. Several conditions may influence distribution, the species is mainly limited to within winter or all year round zones of rainfall. Population of breeding pairs varies from nine to 19 pairs. It is the commonest species in the area. There is a 25% annual adult mortality with life expectancy of an adult about three years. Competition for food is negligible. Predators concern mainly the nesting cycle. Clutch size which is two or three is not regulated by food supply or population changes. Main changes are due to emigration and immigration which is apparently influenced by density-independent factors

Disproportionate mortality of males in a population of springbok (Artiodactyla: Bovidae)

The hypothesis that an imbalanced sex ratio, favouring females, in populations of springbok (Anti-dorcas marsupialis) is the result of disproportionate mortality of males is tested by comparing the sex ratio in a sample of 50 carcasses with that in a population of live springbok from the same geographical area. The results are consistent with this pypothesis. A suggested refinement of the hypothesis is that the disproportionate male mortality falls most heavily on young adult males which are in close association with springbok territories. Possible causes of this age- and sex-linked mortality are discussed

The role of climate in determining the ontogeny trends of low Arctic lakes, south-western Greenland

This thesis uses palaeolimnological records to reconstruct Holocene ontogeny trends from four lakes in south western Greenland. The research addresses four hypotheses investigating how Holocene lake ontogeny trends vary under different climatic settings, how long-term changes in ontogeny relate to periods of established climatic change in the region, the similarities between proxies within the lakes and between the lakes, and the role of vegetation in lake ontogeny. The study region occupies the widest ice-free area of south western Greenland and is characterised by a climatic gradient. The area inland and nearer to the ice-margin is arid, receives less precipitation and is warmer relative to the coastal areas. A paired lake approach, using lake records from two inland lakes and two coastal lakes, was adopted to examine the role of climatic setting upon lake development trajectories. Specifically, diatoms were used to reconstruct DI-alkalinity from the lakes using a DI-alkalinity model created from existing training sets in the region (WA Cla model, r2boot = 0.76, RMSEP = 0.28 log alkalinity units), sedimentary pigments to investigate trends in production and sedimentary parameters to reconstruct organic and minerogenic accumulation rates. All four lakes experienced comparable Holocene long-term ontogeny trajectories; maximum alkalinity in the first ~ 1000 cal. year BP of deglaciation followed by maximum production during the peak of Holocene Thermal Maximum (HTM) warming (~7000 -6000 cal. years BP). Following the HTM, all lakes demonstrated oligotrophication and a decline in pH. Vegetation development and catchment stabilisation at the end of the HTM may be important in determining the onset of oligotrophication in vegetated catchments. However, the impact of vegetation development on lake ontogeny cannot be isolated from the changes in the lakes associated with the colder and wetter climate which occurred at the end of the peak HTM warming. The timings of the large transitions in the ontogeny trajectories are comparable with established periods of Holocene climatic variability in the region; climate forcing drives ontogeny in these lakes. However, there are short-term differences between the lakes indicating that lakes have different thresholds of ecological change and may respond differently to the same climate forcing. It is concluded that ontogeny is driven by climate but lakes may respond differently to forcing depending on catchment specific characteristics which can filter out the climate signal or cause climate to influence the lake in a more direct way