Evolution of dental traits since latest Pleistocene in meadow voles (Microtus pennsylvanicus) from Virginia

Paleobiology ◽  
1990 ◽  
Vol 16 (3) ◽  
pp. 370-383 ◽  
Author(s):  
Anthony D. Barnosky
Keyword(s):  
Microtus Pennsylvanicus ◽  
Geographic Range ◽  
Hudson Bay ◽  
Dental Morphology ◽  
Peripheral Population ◽  
Shape Factors ◽  
Future Studies ◽  
The Third ◽  
Dental Traits ◽  
Tooth Length

Digitizing the third upper molars of Microtus pennsylvanicus reveals evolutionary change in some traits but stability in others during the last 30,000 years. Fossils from Strait Canyon, Virginia (radiocarbon dated between 29,870 + 1,800/-1,400 and 17,880 ± 150 yr B.P.) were compared with modern samples from the margin of the species' conterminous geographic range: Virginia, Colorado, Alaska, and Hudson Bay. Since the late Pleistocene a modification from narrow to wide teeth took place in the eastern populations but not in the western ones, and populations in Virginia apparently evolved wider confluence between triangles 1 and 2. Traits that remained stable through time in the Virginia area, but not necessarily elsewhere, include the numerical shape factors of the occlusal surface and the posterior loop. Potentially widespread stability is evident in the perimeter of the posterior loop relative to total tooth perimeter. Tooth length forms a geographic cline, in which both the fossil and modern populations from Virginia occupy the same position. A peripheral population from southern Colorado shows the most derived dental morphology. These morphological relationships suggest that mosaic evolution operates in arvicoline lineages and provide testable paradigms for future studies.

Biographical Studies of G.I. Gurdjieff

2016 ◽  
Vol 11 (1) ◽  
pp. 10-35
Author(s):  
Joseph Azize
Keyword(s):  
Comparative Research ◽  
Source Material ◽  
Future Studies ◽  
The Third ◽  
The Subject

The various published biographies and biographical notices of G.I. Gurdjieff (c.1865-1949) are of diverse style, quantity and content. While some have made considerable contributions to the subject, most attempts have reacted for or against Gurdjieff’s status as what might call an ‘Enlightened Master’. Little biographical writing on Gurdjieff has questioned the scope, reliability and prejudices of the sources. Further, possible resources have been neglected. The development in Gurdjieff’s ideas is often overlooked, his life is not sufficiently related to that development, and the lack of comparative research has failed to highlight Gurdjieff’s unique contributions. This article is structured in four parts. The first is an introduction, followed by an overview of existing biographical studies of Gurdjieff. The third part addresses bias in these studies, and this is followed by suggestions for future studies. It is concluded that fieldwork regarding the biography of Gurdjieff has been hampered by imperfect methodology. However, with better use of the source material, some of which has only recently been discovered, and a rigorous use of sources, a more balanced and nuanced picture of Gurdjieff’s life, and the development of his ideas and methods, should emerge.

scholarly journals Morphological variation of the deciduous second molars in the Baka Pygmies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Petra G. Šimková ◽  
Gerhard W. Weber ◽  
Fernando V. Ramirez Rozzi ◽  
Lotfi Slimani ◽  
Jérémy Sadoine ◽  
...  
Keyword(s):  
Growth Rate ◽  
Morphological Variation ◽  
Growth Pattern ◽  
Distal Region ◽  
Dental Morphology ◽  
Human Sample ◽  
Different Populations ◽  
Dental Traits ◽  
South Americans ◽  
Range Of Variation

AbstractThe Baka Pygmies are known for their short stature resulting from a reduced growth rate during infancy. They are peculiar also for their teeth erupt earlier than in any other African population, and their posterior dentition is larger than in non-Pygmy populations. However, the Baka’s dental morphology, like several other aspects of their biology, is still understudied. Here, we explore the variation of the Baka’s deciduous upper and lower second molars (dm2s) in comparison to a geographically heterogeneous human sample by means of 3D geometric morphometrics and analysis of dental traits. Our results show that the different populations largely overlap based on the shape of their dm2s, especially the lower ones. Their distal region and the height of the dentinal crown differ the most, with the Baka showing the most extreme range of variation. Upper and lower dm2s covary to a great extent (RV = 0.82). The Baka’s and South Americans’ dm2s were confirmed among the largest in our sample. Despite the Baka’s unique growth pattern, long-lasting isolation, and extreme dental variation, it is not possible to distinguish them from other populations based on their dm2s’ morphology only.

scholarly journals Testing the utility of dental morphological trait combinations for inferring human neutral genetic variation

2020 ◽  
Vol 117 (20) ◽  
pp. 10769-10777 ◽  
Author(s):  
Hannes Rathmann ◽  
Hugo Reyes-Centeno
Keyword(s):  
Modern Human ◽  
Genomic Variation ◽  
Future Research ◽  
Human Populations ◽  
Dental Morphology ◽  
Genomic Signatures ◽  
Neutral Genetic Variation ◽  
Tooth Form ◽  
Dental Traits ◽  
Population Affinity

Researchers commonly rely on human dental morphological features in order to reconstruct genetic affinities among past individuals and populations, particularly since teeth are often the best preserved part of a human skeleton. Tooth form is considered to be highly heritable and selectively neutral and, therefore, to be an excellent proxy for DNA when none is available. However, until today, it remains poorly understood whether certain dental traits or trait combinations preserve neutral genomic signatures to a greater degree than others. Here, we address this long-standing research gap by systematically testing the utility of 27 common dental traits and >134 million possible trait combinations in reflecting neutral genomic variation in a worldwide sample of modern human populations. Our analyses reveal that not all traits are equally well-suited for reconstructing population affinities. Whereas some traits largely reflect neutral variation and therefore evolved primarily as a result of genetic drift, others can be linked to nonstochastic processes such as natural selection or hominin admixture. We also demonstrate that reconstructions of population affinity based on many traits are not necessarily more reliable than those based on only a few traits. Importantly, we find a set of highly diagnostic trait combinations that preserve neutral genetic signals best (up to x∼r = 0.580; 95% r range = 0.293 to 0.758; P = 0.001). We propose that these trait combinations should be prioritized in future research, as they allow for more accurate inferences about past human population dynamics when using dental morphology as a proxy for DNA.

The Effect of Antenatal Neuroprotective Magnesium Sulfate Treatment on Cerebral Oxygenation in Preterm Infants

2020 ◽  
Author(s):  
Buse Ozer Bekmez ◽  
Yüksel Oğuz ◽  
Hayriye Gözde Kanmaz Kutman ◽  
Dilek Uygur ◽  
Fuat Emre Canpolat ◽  
...  
Keyword(s):  
Magnesium Sulfate ◽  
Preterm Infants ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Postnatal Life ◽  
Regional Cerebral Oxygen Saturation ◽  
Future Studies ◽  
The Third ◽  
Early Postnatal Life ◽  
Underlying Mechanisms

Abstract Objective Antenatal magnesium sulfate (MgSO4) treatment is associated with reduced risk of cerebral palsy in preterm infants. We aimed to investigate whether this treatment leads to any alterations on cerebral hemodynamics which could be detected by near-infrared spectroscopy (NIRS) readings in early postnatal life. Study design Infants with gestational ages (GAs) ≤ 32 weeks were divided into two groups regarding their exposure to antenatal neuroprotective MgSO4 treatment or not. NIRS monitoring was performed to all infants, and readings were recorded for 2 hours each day during the first 3 days of life. The primary aim was to compare regional cerebral oxygen saturation (rcSO2) and cerebral fractional tissue oxygen extraction (cFTOE) between the groups. Results Sixty-six infants were exposed to antenatal MgSO4, while 64 of them did not. GA and birth weight were significantly lower in the treatment group (p < 0.01). No difference was observed in rcSO2 and cFTOE levels in the first, second, and the third days of life (p > 0.05). An insignificant reduction in severe intraventricular hemorrhage rates was observed (8 vs. 15%, p = 0.24). Conclusion We could not demonstrate any effect on cerebral oxygenation of preterm infants in early postnatal life that could be attributed to antenatal neuroprotective MgSO4 treatment. Future studies are warranted to clarify the exact underlying mechanisms of neuroprotection.

Polymathy: A New Outlook

2018 ◽  
Vol 3 (Fall 2018) ◽  
pp. 66-82 ◽  
Author(s):  
Michael Espindola Araki
Keyword(s):  
Developmental Model ◽  
The Novel ◽  
Research Practice ◽  
New Model ◽  
Future Studies ◽  
Life Project ◽  
The Third ◽  
New Perspective

This article aims to contribute to the study of polymathy by introducing novel perspectives on the phenomenon and by advancing a new model that systematizes the different variables involved in its development. The article is divided into four sections. The first section involves a reflection about the nature of polymathy; the term mathema is presented as the unit that underpins the development of polymathic knowledge, and the elements that constitute the fundamental qualities of polymathy are identified and discussed. In the second section, the novel conceptualization of polymathy as a life project is introduced; it builds upon previous psychoeconomic approaches to offer a new perspective on the phenomenon. In the third sec- tion, a developmental model of polymathy is suggested; it organizes the different constructs involved in the development of polymathy into a framework that can serve as basis for future studies. Finally, implications for research, practice and policy are discussed.

scholarly journals MODELOS REDUZIDOS APLICADOS AO ENSINO DE GEOGRAFIA: A FORMAÇÃO DE DOLINAS E A EVOLUÇÃO DO RELEVO CÁRSTICO

2020 ◽  
Vol 11 (38) ◽  
pp. 01-17
Author(s):  
Péricles Souza Lima ◽  
◽  
Fernando de Morais ◽  
Keyword(s):  
Higher Education ◽  
Learning Process ◽  
Early Years ◽  
The Other ◽  
Geographic Education ◽  
Future Studies ◽  
Stochastic Nature ◽  
The Third ◽  
Teaching Learning ◽  
Analog Models

The present study constituted simulations ofthe formation of dolines by using reduced analog models and it looked for contributing to the teaching-learning process of geographic education. The research was carried out using a wooden box, which was adapted with a reservoir that recharged the system,and a space for the superposition of the sedimentary layers. Altogether, four experiments were conducted, which enabled analytical and didactic interpretations. The first two, due to their stochastic nature, encourage future studies. The last two presented doliniform features, with the third coming closer to the natural scenerio. On the other hand, the fourth test was more didactic. Such a test was done under controlled conditions, and could contribute more to the geographic education in the early years, unlike the third, conducive to higher education.

scholarly journals Higher Grading Standards and Academic Motivation: Perceptions of Students and Teachers in a Lagos (Nigeria) Private Secondary School

2020 ◽  
Vol 9 ◽  
pp. 1-20
Author(s):  
Innocent Uche Anazia
Keyword(s):  
Secondary School ◽  
Academic Motivation ◽  
Study Data ◽  
Low Achievers ◽  
High Achievers ◽  
Future Studies ◽  
The Third ◽  
Interview Technique ◽  
Perceptions Of Students ◽  
Grading Standards

Abstract This study used qualitative research method to investigate the views of students and teachers of a private secondary school in Lagos State, Nigeria on whether higher grading standards motivate students. The study was prompted by the decision of the management of the school to increase its grading standard. To guide the study, 10 students and 7 teachers participated in the study. Data were generated using interview technique which centred on three objectives or themes of the study. However, the second objective of the study was targeted at the students, while the third objective or theme was targeted at the teachers. Thematic analysis was used to analyze the perceptions of the students and teachers. The findings revealed that higher grading standards motivate students to study harder and that higher standards benefit both high-achievers and low-achievers. Considering that the study was the first attempt to investigate the issue as it concerns Nigeria, suggestions were made on future studies.    

scholarly journals SARS – COV-2 (COVID-19) Pandemic: A Critical Review on Novel Coronavirus Pathogenesis, Clinical Diagnosis and Treatment

2020 ◽  
Vol 10 (3) ◽  
pp. 241-252
Author(s):  
Ruchi Jain ◽  
Nilesh Jain ◽  
Surendra Kumar Jain ◽  
Ram C Dhakar
Keyword(s):  
World Health ◽  
The Novel ◽  
Global Public Health ◽  
Future Studies ◽  
The Public ◽  
The Third ◽  
Treatment And Prevention ◽  
Published Evidence ◽  
Novel Coronavirus ◽  
Health Organization

The 2019-nCoV is officially called SARS-CoV-2 and the disease is named COVID-19. The Novel coronavirus (SARS-CoV-2) caused pneumonia in Wuhan, China in December 2019 is a highly contagious disease. The World Health Organization (WHO) has declared it as a global public health emergency. This is the third serious Coronavirus outbreak in less than 20 years, following SARS in 2002–2003 and MERS in 2012. Currently, the research on novel coronavirus is still in the primary stage. It is currently believed that this deadly Coronavirus strain originated from wild animals at the Huanan market in Wuhan by Bats, snakes and pangolins have been cited as potential carriers. On the basis of current published evidence, we systematically summarize the epidemiology, clinical characteristics, diagnosis, treatment and prevention of COVID-19. This review in the hope of helping the public effectively recognize and deal with the novel coronavirus (SARS-CoV-2) and providing a reference for future studies. Keywords: SARS-CoV-2, COVID-19, Coronavirus, pneumonia, Respiratory infection

"Challenges of using educational platforms and suggestions to address them from the perspective of first-field students at Al Sharqiyah University, Sultanate of Oman"

2022 ◽  
pp. 80-97
Author(s):  
رابعة بنت محمد بن مانع الصقرية ◽  
ثرياء بنت سليمان بن حمد الشبيبية
Keyword(s):  
Electronic Devices ◽  
Technical Support ◽  
Point Of View ◽  
Sultanate Of Oman ◽  
Payment Method ◽  
Future Studies ◽  
The Third ◽  
Descriptive Approach ◽  
Internet Networks ◽  
Answering Questions

The study aimed to explore the challenges of using educational platforms and proposals to address them from the point of view of the third-year students at Al-Sharqiya University. The descriptive approach was used on a sample of the third-year students at Al-Sharqiya University in the specialization of the first field, consisting of (100) students. The study tool consisted of a two-axis questionnaire to identify the challenges of Use of educational platforms and proposals to address them. The study concluded that among the main challenges of students' use of educational platforms are weak Internet networks and their lack of coverage in some places, some students not having their own computers, and the lack of technical support when needed. The results showed that among the proposals to address the challenges are the following: Strengthening internet networks in some areas and making them available for free for educational purposes, and providing personal computers for students who need them at subsidized prices and an easy payment method, in addition to providing the necessary technical support through the establishment of a special platform that includes answering questions directly, as well as educating students about the harms of staying long hours in front of electronic devices. The results of this study were discussed in the light of latest reviewed literature followed by recommendations and suggestions for future studies and investigations.

Sign in / Sign up

Export Citation Format

Share Document