170,137 research outputs found
3D enamel thickness in Neandertals and Homo sapiens permanent lower canines
No full textOver the last decades, the growing support of 3D data has led to develop comparative morphometric and qualitative methods to
increase the number of fossils suitable for more comprehensive dental analysis [1]. Enamel thickness figures prominently in studies
of human evolution, particularly with hominoid taxonomy, phylogeny, and paleodiet [2, 3]. Attention has focused on molar
teeth, recently utilising advanced technologies with novel protocols [3]. Despite important results achieved thus far, further work
is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth [4] to investigate 3D enamel
thickness of hominin canines. MicroCT data of 38 unworn/lightly worn Homo sapiens (Early: n= 4; Upper Paleolithic: n=4; Recent:
n=21) and Neandertal (n=9) permanent lower canines were segmented using Avizo 7 to reconstruct 3D digital models of the
teeth. The cervical line was digitized on each 3D model using the spline function in Rapidform XOR to separate crown from root
dentine. Volumes of enamel and of crown dentine, and the enamel-dentine junction surface were measured to compute Relative
Enamel Thickness (RET). Mean RET value for Neandertals (12.7±1.8) falls below the mean computed for H. sapiens (Upper Paleolithic=
15.6±2.9; Early=14.0±1.9; Recent=15.5±2.6). Results of the permutation test between Neandertal and recent humans
support the significant difference in RET (p=0.0055), a useful index for the taxonomic discrimination between modern humans
and Neandertals. This preliminary study confirms this trend for lower permanent canines [2], using a 3D protocol which is reproducible,
has little subjectivity, and is particularly effective for the uneven contour of cervical enamel in anterior teeth. In recent
literature, although the majority of datasets are based on micro-CT scans, the analysis of dental tissues in Neandertal and H. sapiens
permanent lower canines have been performed on virtual longitudinal sections [2, 5]. Our preliminary 3D analysis of permanent
lower canines support the general findings that Neandertal have thinner enamel than H. sapiens, as observed in molars. Future
contributions will incorporate increased sample sizes and include worn teeth to investigate whether the RET index continues to
discriminate between Neandertal and H. sapiens canines.
Acknowledgements: We thank all the curators and collaborators that granted us access to the dental material and the CT-operators
at MPI-EVA.
References:[1] Le Cabec, A., Tang, N., Tafforeau, P., 2015. Accessing Developmental Information of Fossil Hominin Teeth
Using New Synchrotron-Microtomography Based Visualization Techniques of Dental Surfaces and Interfaces. PLoS ONE 10(4):
e0123019. doi:10.1371/journal.pone.0123019[2] Smith, T.M., Olejniczak, A.J., Zermeno, J.P., Tafforeau, P., Skinner, M.M.,
Hoffmann, A., Radovcic, J., Toussaint, M., Kruszynski, R., Menter, C., Moggi- Cecchi, J., Glasmacher, U.A., Kullmer, O.,
Schrenk, F., Stringer, C., Hublin, J.-J., 2012. Variation in enamel thickness within the genus Homo. J. Hum. Evol. 62,395e411.[3]
Olejniczak, A.J., Smith, T.M., Feeney, R.N.M., Macchiarelli, R., Mazurier, A.,Bondioli, L., Rosas, A., Fortea, J., de la Rasilla, M.,
Garcia-Tabernero, A., Radovcic, J., Skinner, M.M., Toussaint, M., Hublin, J.-J., 2008. Dental tissue proportions and enamel
thickness in Neandertal and modern human molars. J. Hum. Evol. 55, 12e23.[4] Benazzi, S., Panetta, D., Fornai, C., Toussaint,
M., Gruppioni, G., Hublin, J-J., 2014. Technical Note: Guidelines for the digital computation of 2D and 3D enamel thickness in
hominoid teeth. Am. J. Phys. Anthropol. 2014 Feb;153(2):305-13.[5] Feeney, R.N.M., Zermeno, J.P., Reid, D.J., Nakashima, S.,
Sano, H., Bahar, A., Hublin, J-J., Smith, T.S., 2010. ’Enamel thickness in Asian human canines and premolars’. Anthrop. Sci., 118
(3):191-198
Bulletins et Mémoires de la Société d'Anthropologie de Paris, n.s., 1989, I (3-4), n° spéc. : Histoire de l'anthropologie : hommes idées, moments. S. dir. C. Blanckaert, A. Ducros & J.-J. Hublin
No full textMasset Claude. Bulletins et Mémoires de la Société d'Anthropologie de Paris, n.s., 1989, I (3-4), n° spéc. : Histoire de l'anthropologie : hommes idées, moments. S. dir. C. Blanckaert, A. Ducros & J.-J. Hublin. In: L'Homme, 1992, tome 32 n°121. Anthropologie du proche. pp. 238-239
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Unravelling the functional biomechanics of dental features and tooth wear
No full textMost of the morphological features recognized in hominin teeth, particularly the topography of the occlusal surface, are generally interpreted as an evolutionary functional adaptation for mechanical food processing. In this respect, we can also expect that the general architecture of a tooth reflects a response to withstand the high stresses produced during masticatory loadings. Here we use an engineering approach, finite element analysis (FEA), with an advanced loading concept derived from individual occlusal wear information to evaluate whether some dental traits usually found in hominin and extant great ape molars, such as the trigonid crest, the entoconid-hypoconulid crest and the protostylid have important biomechanical implications. For this purpose, FEA was applied to 3D digital models of three Gorilla gorilla lower second molars (M2) differing in wear stages. Our results show that in unworn and slightly worn M2s tensile stresses concentrate in the grooves of the occlusal surface. In such condition, the trigonid and the entoconid-hypoconulid crests act to reinforce the crown locally against stresses produced along the mesiodistal groove. Similarly, the protostylid is shaped like a buttress to suffer the high tensile stresses concentrated in the deep buccal groove. These dental traits are less functional in the worn M2, because tensile stresses decrease physiologically in the crown with progressing wear due to the enlargement of antagonistic contact areas and changes in loading direction from oblique to nearly parallel direction to the dental axis. This suggests that the wear process might have a crucial influence in the evolution and structural adaptation of molars enabling to endure bite stresses and reduce tooth failure throughout the lifetime of an individual
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The effectiveness of using carbonate isotope measurements of body tissues to infer diet in human evolution: Evidence from wild western chimpanzees (Pan troglodytes verus)*
No full textChanges in diet throughout hominin evolution have been linked with important evolutionary changes. Stable carbon isotope analysis of inorganic apatite carbonate is the main isotopic method used to reconstruct fossil hominin diets; to test its effectiveness as a paleodietary indicator we present bone and enamel carbonate carbon isotope data from a well-studied population of modern wild western chimpanzees (Pan troglodytes verus) of known sex and age from Taï, Cote d'Ivoire.We found a significant effect of age class on bone carbonate values, with adult chimpanzees being more 13C- and 18O-depleted compared to juveniles. Further, to investigate habitat effects, we compared our data to existing apatite data on eastern chimpanzees (P. troglodytes schweinfurthii) and found that the Taï chimpanzees are significantly more depleted in enamel d13Cap and d18Oap compared to their eastern counterparts. Our data are the first to present a range of tissue-specific isotope data from the same group of wild western chimpanzees and, as such, add new data to the growing number of modern non-human primate comparative isotope datasets providing valuable information for the interpretation of diet throughout hominin evolution. By comparing our data to published isotope data on fossil hominins we found that our modern chimpanzee bone and enamel data support hypotheses that the trend towards increased consumption of C4 foods after 4 Ma (millions of years ago) is unique to hominins
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Self-reported sleep bruxism and mortality in 1990–2020 in a nationwide twin cohort
No full textBackground: The association of sleep bruxism with mortality has not been studied. Objectives: Altogether 12 040 subjects from the nationwide Finnish twin cohort were included in the analyses. We examined whether self-reported sleep bruxism is associated with increased risk of mortality, and if so, whether the effect is independent of known common risk factors. The time span of the follow-up was 30 years. Methods: Cox proportional hazards regression models (Hazard Ratios and their 95% Confidence Intervals) adjusted by age, sex and covariates were used to assess the effect of baseline bruxism status in 1990 on future mortality in 1990–2020. Results: The risk of mortality among all participants (n = 12 040), independent of missing covariates and adjusted by age and sex, was 40% higher in weekly bruxers than in never bruxers (HR 1.40, 95% CI 1.16–1.68, p <.001). However, when adjusted by all studied covariates, (n = 11 427) the risk was no longer observed (HR 1.04, 95% CI 0.86–1.25, p =.717). Despite the overall lack of between bruxism and mortality after adjustment for covariates, we examined the cause-specific risks for major cause-of-death groups. There were no substantial associations of weekly bruxism with major disease outcomes by the fully adjusted hazard ratios for them. Conclusion: Bruxism does not kill—in line with its definition of being rather a behaviour (with all its phenotypes) than a disease
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