Hippo pathway/Yap regulates primary enamel knot and dental cusp patterning in tooth morphogenesis.
Kwon, Hyuk-Jae Edward; Li, Liwen; Jung, Han-Sung
2015-11-01
The shape of an individual tooth crown is primarily determined by the number and arrangement of its cusps, i.e., cusp patterning. Enamel knots that appear in the enamel organ during tooth morphogenesis have been suggested to play important roles in cusp patterning. Animal model studies have shown that the Hippo pathway effector Yap has a critical function in tooth morphogenesis. However, the role of the Hippo pathway/Yap in cusp patterning has not been well documented and its specific roles in tooth morphogenesis remain unclear. Here, we provide evidence that Yap is a key mediator in tooth cusp patterning. We demonstrate a correlation between Yap localization and cell proliferation in developing tooth germs. We also show that, between the cap stage and bell stage, Yap is crucial for the suppression of the primary enamel knot and for the patterning of secondary enamel knots, which are the future cusp regions. When Yap expression is stage-specifically knocked down during the cap stage, the activity of the primary enamel knot persists into the bell-stage tooth germ, leading to ectopic cusp formation. Our data reveal the importance of the Hippo pathway/Yap in enamel knots and in the proper patterning of tooth cusps.
Cho, Sung-Won; Kim, Jae-Young; Cai, Jinglei; Lee, Jong-Min; Kim, Eun-Jung; Lee, Hyun-A; Yamamoto, Hitoshi; Jung, Han-Sung
2007-02-01
The enamel knot (EK), which is a transient signaling center in the tooth germ, regulates both the differential growth of the dental epithelium and the tooth shape. In this study, the regeneration of the EK was evaluated. The EK regions were removed from the E14 and E16 dental epithelia, and the remaining epithelia were recombined with their original dental mesenchymes. All these tooth germs could develop into calcified teeth after being transplanted into the kidney capsule for 3 weeks. One primary EK was regenerated earlier, and two or three secondary EKs were regenerated later in culture. When simply recombined without removing the EK, the tooth germ, which had four secondary EKs and four cuspal areas of the dental papilla, generated one primary EK first and subsequent secondary EKs. These results indicate that the patterning of the EK in all tooth germs always starts from a primary EK independent of the direct epithelial or mesenchymal control. This suggests that neither the dental epithelium nor the dental mesenchyme can dictate the pattern or number of the EK formation, but the interaction between the dental epithelium and the dental mesenchyme is essential for the regeneration and patterning of the EKs.
Luukko, Keijo; Løes, Sigbjørn; Furmanek, Tomasz; Fjeld, Karianne; Kvinnsland, Inger Hals; Kettunen, Paivi
2003-03-01
The final shape of the molar tooth crown is thought to be regulated by the transient epithelial signaling centers in the cusp tips, the secondary enamel knots (SEKs), which are believed to disappear after initiation of the cusp growth. We investigated the developmental fate of the signaling center using the recently characterized Slit1 enamel knot marker as a lineage tracer during morphogenesis of the first molar and crown calcification in the mouse. In situ hybridization analysis showed that after Fgf4 downregulation in the SEK, Slit1 expression persisted in the deep compartment of the knot. After the histological disappearance of the SEK, Slit1 expression was evident in a novel epithelial cell cluster, which we call the tertiary enamel knot (TEK) next to the enamel-free area (EFA)-epithelium at the cusp tips. In embryonic tooth, Slit1 was also observed in the stratum intermedium (SI) and stellate reticulum cells between the parallel SEKs correlating to the area where the inner enamel epithelium cells do not proliferate. After birth, the expression of Slit1 persisted in the SI cells of the transverse connecting lophs of the parallel cusps above the EFA-cells. These results demonstrate the presence of a novel putative signaling center, the TEK, in the calcifying tooth. Moreover, our results suggest that Slit1 signaling may be involved in the regulation of molar tooth shape by regulating epithelial cell proliferation and formation of EFA of the crown.
Tooth and scale morphogenesis in shark: an alternative process to the mammalian enamel knot system.
Debiais-Thibaud, Mélanie; Chiori, Roxane; Enault, Sébastien; Oulion, Silvan; Germon, Isabelle; Martinand-Mari, Camille; Casane, Didier; Borday-Birraux, Véronique
2015-12-24
The gene regulatory network involved in tooth morphogenesis has been extremely well described in mammals and its modeling has allowed predictions of variations in regulatory pathway that may have led to evolution of tooth shapes. However, very little is known outside of mammals to understand how this regulatory framework may also account for tooth shape evolution at the level of gnathostomes. In this work, we describe expression patterns and proliferation/apoptosis assays to uncover homologous regulatory pathways in the catshark Scyliorhinus canicula. Because of their similar structural and developmental features, gene expression patterns were described over the four developmental stages of both tooth and scale buds in the catshark. These gene expression patterns differ from mouse tooth development, and discrepancies are also observed between tooth and scale development within the catshark. However, a similar nested expression of Shh and Fgf suggests similar signaling involved in morphogenesis of all structures, although apoptosis assays do not support a strictly equivalent enamel knot system in sharks. Similarities in the topology of gene expression pattern, including Bmp signaling pathway, suggest that mouse molar development is more similar to scale bud development in the catshark. These results support the fact that no enamel knot, as described in mammalian teeth, can be described in the morphogenesis of shark teeth or scales. However, homologous signaling pathways are involved in growth and morphogenesis with variations in their respective expression patterns. We speculate that variations in this topology of expression are also a substrate for tooth shape evolution, notably in regulating the growth axis and symmetry of the developing structure.
Demineralization of enamel in primary second molars related to properties of the enamel.
Sabel, N; Robertson, A; Nietzsche, S; Norén, J G
2012-01-01
Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical and mineral composition of the enamel. A demineralized lesion was created in second primary molars from 18 individuals. Depths of lesions were then related to individual chemical content of the enamel. Enamel responded to demineralization with different lesion depths and this was correlated to the chemical composition. The carbon content in sound enamel was shown to be higher where lesions developed deeper. The lesion was deeper when the degree of porosity of the enamel was higher.
Demineralization of Enamel in Primary Second Molars Related to Properties of the Enamel
N. Sabel
2012-01-01
Full Text Available Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical and mineral composition of the enamel. A demineralized lesion was created in second primary molars from 18 individuals. Depths of lesions were then related to individual chemical content of the enamel. Enamel responded to demineralization with different lesion depths and this was correlated to the chemical composition. The carbon content in sound enamel was shown to be higher where lesions developed deeper. The lesion was deeper when the degree of porosity of the enamel was higher.
Analysis of some elements in primary enamel during postnatal mineralization.
Sabel, Nina; Klinberg, Gunilla; Nietzsche, Sandor; Robertson, Agneta; Odelius, Hans; Norén, Jörgen G
2009-01-01
The primary teeth start to mineralize in utero and continue development and maturation during the first year of life.The aim of this study was to investigate the concentrations of some elements, C, F, Na, Mg, Cl, K and Sr, by secondary ion mass spectrometry (SIMS) in human primary incisors at different stages of mineralization.The teeth derived from an autopsy material from children who had died in sudden infant death.The buccal enamel of specimens from the ages 1, 2, 3, 4, 6 and 19 months, respectively, was analyzed. It was evident that posteruptive effects play an important role in composition of the outermost parts of the enamel. Before the tooth erupts, the concentrations of the elements vary with the maturation grade of the mineralization in the enamel. Sodium was the element with the highest concentration of the measured elements and chlorine was the element of lowest concentration.The 19 month old specimen, considered as the only mature and erupted tooth, showed to differ from the other specimens.The concentration of fluorine, in the 19 month old specimen's outermost surface, is readily seen higher compared with the other specimens at this depth zone. In the 19 month old specimen the concentration of carbon is lower. Potassium, sodium and chlorine have higher concentrations, in general, in the 19 month old specimen compared with the immature specimens. The thickness of the enamel during mineralization was calculated from data from SIMS.The thickness of the buccal enamel of primary incisors seemed to be fully developed between 3-4 months after birth, reaching a thickness of 350-400 microm.
Developmental enamel defects in the primary dentition: aetiology and clinical management
Salanitri, S; Seow, WK
2013-01-01
...‐ and postnatal environment. The presence of enamel hypoplasia increases the risk of primary teeth to early childhood caries and tooth wear as the defective enamel is thinner, more plaque retentive and less resistant...
Microstructural analysis of demineralized primary enamel after in vitro toothbrushing
Neves Aline de Almeida
2002-01-01
Full Text Available The aim of this study was to investigate, in vitro, the morphological characteristics of demineralized primary enamel subjected to brushing with a dentifrice with or without fluoride. In order to do so, 32 enamel blocks were divided in 4 different groups containing 8 blocks each. They were separately immersed in artificial saliva for 15 days. The experimental groups were: C - control; E - submitted to etching with 37% phosphoric acid gel (30 s; EB - submitted to etching and brushing 3 times a day with a non-fluoridated dentifrice; EBF = submitted to etching and brushing 3 times a day with a fluoridated dentifrice. The toothbrushing force was standardized at 0.2 kgf and 15 double strokes were performed on each block. After the experimental period, the samples were prepared and examined under SEM. The control group (C showed a smooth surface, presenting scratches caused by habitual toothbrushing. The etched samples (E exhibited different degrees of surface disintegration, but the pattern of acid etching was predominantly the type II dissolution. The brushed surfaces were smooth, with elevations which corresponded to the exposure of Tomes? process pits and depressions which corresponded to interrod enamel. Particles resembling calcium carbonate were found in the most protected parts of the grooves. No morphological differences were observed between brushing with fluoridated (EBF and non-fluoridated (EB dentifrice. The results suggest that the mechanical abrasion caused by brushing demineralized enamel with dentifrice smoothes the rough etched surface, and the presence of fluoride does not cause morphological modifications in this pattern.
Demineralization of Enamel in Primary Second Molars Related to Properties of the Enamel
N. Sabel; Robertson, A; Nietzsche, S.; Norén, J. G.
2012-01-01
Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical an...
MicroCT study on the enamel mineral density of primary molars
Elfrink, M.E.C.; Kalin, K.; van Ruijven, L.J.; ten Cate, J.M.; Veerkamp, J.S.J.
2016-01-01
Aim The aim of this study is to report on the mineral density of the enamel of primary molars related to the age of the child and to compare the mineral density of sound and carious enamel in those molars. Materials and methods This study included 23 children and 41 extracted primary molars. The
Knirsch, M S; Bonifácio, C C; Shimaoka, A M; Andrade, A P; Carvalho, R C R
2009-06-01
This study aims to evaluate the bonding effectiveness of self-etch and etch-and-rinse adhesive systems in on intact and ground primary tooth enamel. Sixty primary incisors were divided into 6 groups according to the adhesive system (etch-and-rinse - Adper Single Bond 2 - SB, 2 steps self-etch -Clearfil SE Bond - SE, and 1 step self-etch - One Up Bond F Plus OBF) and to the substrate (ground or intact enamel): G1-SB/intact enamel; G2-SE/intact enamel; G3- OBF/intact enamel; G4-SB/ground enamel; G5- SE/ground enamel and G6-OBF/ground enamel. Microshear bond test specimens were prepared with microhybrid composite and after 24h of water storage the microshear test was performed. Data were submitted to statistical analysis using two-way ANOVA and Tukey's tests (penamel characteristics (ground or intact) only when SE was used a statistically significant difference was found, as G2 (21.12+/-4.52) was statistically lower than G5 (33.29+/-5.44). Among the intact enamel groups, SB (26.11+/-7.56) was statistically superior to SE (21.12+/-4.52) and OBF (17.01+/-3.96). However, when comparisons were made among groups of ground enamel, SE (33.29+/-5.44) was significantly higher than SB (26.35+/-8.18) and OBF (17.52+/-3.46). The two-step self-etch adhesive system is a reliable alternative to etch and rinse adhesive systems on both ground and intact primary enamel.
Human enamel veneer restoration: an alternative technique to restore anterior primary teeth.
Oliveira, Luciana Butini; Tamay, Tereza Keiko; Oliveira, Marta Dutra Machado; Rodrigues, Célia Martins Delgado; Wanderley, Marcia Turolla
2006-01-01
Restoration of severely decayed primary teeth is a clinical challenge in Pediatric Dentistry. Among the restorative treatment options, the use of prefabricated crowns and resin composite restorations, either by means of direct or indirect techniques is mentioned in the literature. The purpose of this article is to describe the rehabilitation of primary anterior teeth in a 5-year-old patient. Dental treatment consisted on an anterior space maintainer prosthesis made with natural primary teeth, plus human dental enamel veneer (facet) restorations. The advantages of this technique are better esthetics and the natural enamel has physiologic wear and offers superficial smoothness and cervical adaptation compatible with those of the surrounding teeth.
Association between enamel hypoplasia and dental caries in primary second molars: a cohort study.
Hong, L; Levy, S M; Warren, J J; Broffitt, B
2009-01-01
The purpose of this study was to assess the longitudinal relationships between enamel hypoplasia and caries experience of primary second molars. The study sample was 491 subjects who received dental examinations at both age 5 and 9 by the calibrated examiners. Four primary second molars (n = 1,892) were scored for the presence of enamel hypoplasia for each participant. Caries presence and number of decayed and filled surfaces (dfs) were determined at age 5 and 9. The relationships between enamel hypoplasia and caries experience were assessed. Among primary second molars, 3.9% of children and 1.7% of primary second molars had enamel hypoplasia. At age 5, 36.8% of children with hypoplasia had caries, while 16.9% of children without enamel hypoplasia had caries. At age 9, the corresponding numbers were 52.6% for children with hypoplasia and 34.5% for children without hypoplasia, respectively. At the tooth level, for age 5, 28.1% of teeth with hypoplasia had caries (mean dfs = 0.40), and 7.6% of teeth without hypoplasia had caries (mean dfs = 0.11). At age 9, the corresponding numbers were 41.9% (mean dfs = 0.76) for teeth with hypoplasia and 18.3% (mean dfs = 0.34) for teeth without hypoplasia. In multivariable logistic regression analyses, teeth of subjects with enamel hypoplasia had a significantly higher risk for caries at age 5 and 9 after controlling for other risk factors. Enamel hypoplasia appears to be a significant risk factor for caries and should be considered in caries risk assessment.
Lukacs, John R.
1999-11-01
This study reports the prevalence, distribution, and expression of enamel defects in a sample of primary teeth (n = 225) from a prehistoric site in western India (1400-700 BC). Five enamel surfaces of individual, isolated primary teeth were observed for surface defects using a binocular stereomicroscope with variable power of magnification (8-20x). Standards for evaluating dental enamel defects (DDE) recommended by the Fédération Dentaire International (FDI) were employed. Details of defect expression were also recorded, including size, shape, and surface of tooth crown affected. Hypoplastic enamel defects were observed in 28% of teeth, but the distribution and expression of defects was not random. More than 50% of canine teeth had hypoplastic defects (HD); incisors and molar teeth exhibited far fewer HD. The buccal surface of canines was the most commonly affected crown surface. Areas of missing enamel were also common on the mesial and distal surfaces of canines and incisors and on the mesial surface of molar teeth. The high frequency of enamel defects found on interproximal crown surfaces warrants a label, and the name interproximal contact hypoplasia (IPCH) is proposed. Linear enamel hypoplasia (LEH) was absent from this primary dental sample. IPCH is more frequent in mandibular than in maxillary teeth, but no side preference was detected. In canine teeth, buccal hypoplasias (localized hypoplasia of primary canines; LHPC) were not positively correlated with interproximal hypoplastic defects. The etiology of IPCH may involve mesial compaction of developing teeth due to slow longitudinal growth of the jaws. Episodic bone remodeling results in ephemeral fenestrae in the mesial and distal walls of the dental crypt permitting tooth-tooth contact and disruption of amelogenesis. IPCH prevalence decreases across the subsistence transition from sedentary Early Jorwe agriculturalists to seminomadic Late Jorwe hunters and foragers, but the difference is not
Elemental composition of normal primary tooth enamel analyzed with XRMA and SIMS.
Sabel, Nina; Dietz, Wolfram; Lundgren, Ted; Nietzsche, Sandor; Odelius, Hans; Rythén, Marianne; Rizell, Sara; Robertson, Agneta; Norén, Jörgen G; Klingberg, Gunilla
2009-01-01
There is an interest to analyze the chemical composition of enamel in teeth from patients with different developmental disorders or syndromes and evaluate possible differences compared to normal composition. For this purpose, it is essential to have reference material. The aim of this study was to, by means of X-ray micro analyses (XRMA) and secondary ion mass spectrometry (SIMS), present concentration gradients for C, O, P and Ca and F, Na, Mg, Cl, K and Sr in normal enamel of primary teeth from healthy individuals. 36 exfoliated primary teeth from 36 healthy children were collected, sectioned, and analyzed in the enamel and dentin with X-ray micro analyses for the content of C, O, P and Ca and F, Na MgCl, K and Sr. This study has supplied reference data for C, O, P and Ca in enamel in primary teeth from healthy subjects. No statistically significant differences in the elemental composition were found between incisors and molars.The ratio Ca/P is in concordance with other studies. Some elements have shown statistically significant differences between different levels of measurement. These results may be used as reference values for research on the chemical composition of enamel and dentin in primary teeth from patients with different conditions and/or syndromes.
[The study on chemical composition and crystalline structure of hypoplastic primary dental enamel].
Zheng, S; Deng, H; Gao, X
1997-11-01
The present study, firstly, analyzed chemical composition of hypoplastic primary teeth by electron probe analyzer and compared the hypoplastic part with the normal part in the same tooth; secondly, by X-ray diffraction analyzer, studied the hypoplastic dental enamel and the normal dental enamel, and compared the crystalline structure between different dental enamel and with that of the hydroxyapatite. The aim was to find out any change of crystalline structure. Two exfoliated hypoplastic deciduous anterior teeth were used for the electron probe study. The normal part of each tooth served as control. Determinations of weight percentage (wt%) were made for P, Al, Mg, Ca, Mn, Fe, Zn, Sr, Na, K and F. Four exfoliated hypoplastic deciduous anterior teeth and eight exfoliated normal deciduous anterior teeth were used for the X-ray diffraction study. We found by X-ray diffraction that the length of the alpha-axis of enamel crystallite and the distance of lattice plane (corresponding 300) were increased in defective enamel and could be associated with the increased content of magnesium detected by electron probe. Thus, the present study demonstrated that there were both quantity and quality changes in the enamel hypoplasia lesion, which may increase the susceptibility of the defective teeth to caries.
Costa de Almeida, Glauce Regina; Molina, Gabriela Ferian; Meschiari, Cesar Arruda [Department of Morphology, Stomatology and Physiology, Dental School of Ribeirao Preto, University of Sao Paulo - FORP/USP, Av. do Cafe, S/N, Monte Alegre, CEP 14040-904, Ribeirao Preto, SP (Brazil); Barbosa de Sousa, Frederico [Department of Morphology, Dental School of Joao Pessoa, Federal University of Paraiba - UFPB, Av Castelo Branco - Campus I, CEP 58.059-900, Joao Pessoa, PB (Brazil); Gerlach, Raquel Fernanda, E-mail: rfgerlach@forp.usp.br [Department of Morphology, Stomatology and Physiology, Dental School of Ribeirao Preto, University of Sao Paulo - FORP/USP, Av. do Cafe, S/N, Monte Alegre, CEP 14040-904, Ribeirao Preto, SP (Brazil)
2009-09-01
The aims of this study were 1) to verify how close to the theoretically presumed areas are the areas of enamel microbiopsies carried out in vivo or in exfoliated teeth; 2) to test whether the etching solution penetrates beyond the tape borders; 3) to test whether the etching solution demineralizes the enamel in depth. 24 shed upper primary central incisors were randomly divided into two groups: the Rehydrated Teeth Group and the Dry Teeth Group. An enamel microbiopsy was performed, and the enamel microbiopsies were then analyzed by Scanning Electron Microscopy (SEM) and Polarizing Microscopy (PM). Quantitative birefringence measurements were performed. The 'true' etched area was determined by measuring the etched enamel using the NIH Image analysis program. Enamel birefringence was compared using the paired t test. There was a statistically significant difference when the etched areas in the Rehydrated teeth were compared with those of the Dry teeth (p = 0.04). The etched areas varied from - 11.6% to 73.5% of the presumed area in the Rehydrated teeth, and from 6.6% to 61.3% in the Dry teeth. The mean percentage of variation in each group could be used as a correction factor for the etched area. Analysis of PM pictures shows no evidence of in-depth enamel demineralization by the etching solution. No statistically significant differences in enamel birefringence were observed between values underneath and outside the microbiopsy area in the same tooth, showing that no mineral loss occurred below the enamel superficial layer. Our data showed no evidence of in-depth enamel demineralization by the etching solution used in the enamel microbiopsy proposed for primary enamel. This study also showed a variation in the measured diameter of the enamel microbiopsy in nineteen teeth out of twenty four, indicating that in most cases the etching solution penetrated beyond the tape borders.
Morphology of enamel in primary teeth from children in Thailand exposed to environmental lead
Youravong, Nattaporn [Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla (Thailand); Chongsuvivatwong, Virasakdi [Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla (Thailand); Teanpaisan, Rawee [Department of Stomatology, Faculty of Dentistry, Prince of Songkla University, Songkhla (Thailand); Geater, Alan F. [Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla (Thailand); Dietz, Wolfram [Centre of Electron Microscopy, Friedrich-Schiller-University Jena (Germany); Dahlen, Gunnar [Department of Oral Microbiology, Faculty of Odontology, Goeteborg University (Sweden); Noren, Joergen G. [Department of Pedodontics, Faculty of Odontology, Goeteborg University, Box 450 SE-405 30 Goeteborg (Sweden)]. E-mail: Jorgen.noren@odontologi.gu.se
2005-09-15
Lead is one of the major environmental pollutants and a health risk. Dental hard tissues have a capacity to accumulate lead from the environment. Eighty exfoliated primary teeth were collected from children residing around a shipyard area in southern Thailand, known for its lead contamination. The morphology of the enamel was examined by polarized light microscopy (PLM), microradiography (MRG), and scanning electron microscopy (SEM). The specimens derived from two groups of children, one group with high blood levels of lead (57 teeth) and one group having low blood levels of lead (23 teeth). The enamel irrespective of group appeared normal. However, in a majority of the specimens the enamel surface appeared hypomineralized, which was confirmed in SEM. No morphological changes connected to lead in blood could be found. The hypomineralized surface zone could possibly be attributed to an acid oral environment.
Cheong, Youjin [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Choi, Samjin [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Department of Orthodontics, College of Dental Medicine, Kyung Hee University, Seoul (Korea, Republic of); Kim, So Jung [Department of Pediatric Dentistry, College of Dental Medicine, Kyung Hee University, Seoul (Korea, Republic of); Park, Hun-Kuk, E-mail: sigmoidus@khu.ac.kr [Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Program of Medical Engineering, Kyung Hee University, Seoul (Korea, Republic of)
2012-07-01
This study examined the nanostructural effects of fluoride application and the acid-etching time with respect to the time elapsed after fluoride application on the primary and permanent tooth enamel layers using atomic force microscopy (AFM) and scanning electron microscopy (SEM). 192 non-carious teeth were assigned to sixteen experimental groups (n = 12) including primary (1 to 8) and permanent (9 to 16) teeth, based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. The APF pre-treatment led to a decrease in surface roughness in both the primary and permanent teeth. After the APF treatment, the roughness in both primary and permanent teeth increased with the time elapsed. An acid-etching time of 40 s led to increased nanostructural changes in the enamel surfaces compared to the conventional acid-etching time of 20 s. This acid-etching process led to a higher roughness changes in the primary teeth than in the permanent teeth. To obtain proper enamel adhesion of a sealant after APF pre-treatment, it is important to apply acid-etching two weeks after pre-treatment. In addition, the acid-etching time should be prolonged to apply etching more quickly than two weeks, regardless of the primary and permanent teeth. Highlights: Black-Right-Pointing-Pointer APF pre-treatment led to decreased surface roughness in the enamel. Black-Right-Pointing-Pointer After APF treatment, the more roughness increased with increasing time elapsed. Black-Right-Pointing-Pointer Acid-etching should be performed two weeks after fluoride application.
Effect of foods and drinks on primary tooth enamel after erosive challenge with hydrochloric acid.
Mesquita-Guimarães, Késsia Suênia Fidelis de; Scatena, Camila; Borsatto, Maria Cristina; Rodrigues-Júnior, Antonio Luiz; Serra, Mônica Campos
2015-01-01
The aim of this study was to evaluate the effect of industrialised foods and drinks on primary tooth enamel previously eroded with hydrochloric acid (HCl). The crowns of one hundred two specimens were subjected to an erosive challenge with HCl and randomly divided into six groups (n = 17): Chocolate Milk (Toddynho® - Pepsico) - negative control; Petit Suisse Yogurt (Danoninho® - Danone); Strawberry Yogurt (Vigor); Apple puree (Nestlé); Fermented Milk (Yakult® - Yakult); and Home Squeezed Style Orange Juice (del Valle) - positive control. The 28-day immersion cycles for the test products were performed twice daily and were interspersed with exposure of the test substrate to artificial saliva. Measurements of enamel surface microhardness (SMH) were performed initially, after immersion in HCl and at 7, 14, 21 and 28 days of experimentation. A two-way ANOVA, according to a split-plot design, followed by the sum of squares decomposition and Tukey's test, revealed a significant effect for the interaction between Foods and Drinks and Length of Exposure (p < 0.00001). Orange juice resulted in greater mineral loss of enamel after 28 days. None of the test products was associated with recovery of tooth enamel microhardness.
Effect of foods and drinks on primary tooth enamel after erosive challenge with hydrochloric acid
Késsia Suênia Fidelis de MESQUITA-GUIMARÃES
2015-01-01
Full Text Available The aim of this study was to evaluate the effect of industrialised foods and drinks on primary tooth enamel previously eroded with hydrochloric acid (HCl. The crowns of one hundred two specimens were subjected to an erosive challenge with HCl and randomly divided into six groups (n = 17: Chocolate Milk (Toddynho® - Pepsico - negative control; Petit Suisse Yogurt (Danoninho® - Danone; Strawberry Yogurt (Vigor; Apple puree (Nestlé; Fermented Milk (Yakult® - Yakult; and Home Squeezed Style Orange Juice (del Valle - positive control. The 28-day immersion cycles for the test products were performed twice daily and were interspersed with exposure of the test substrate to artificial saliva. Measurements of enamel surface microhardness (SMH were performed initially, after immersion in HCl and at 7, 14, 21 and 28 days of experimentation. A two-way ANOVA, according to a split-plot design, followed by the sum of squares decomposition and Tukey’s test, revealed a significant effect for the interaction between Foods and Drinks and Length of Exposure (p < 0.00001. Orange juice resulted in greater mineral loss of enamel after 28 days. None of the test products was associated with recovery of tooth enamel microhardness.
Zahra Bahrololoomi
2015-04-01
Full Text Available Laser irradiation has been suggested as an adjunct to traditional caries prevention methods. But little is known about the cariostatic effect of diode laser and most studies available are on permanent teeth.The purpose of the present study was to investigate the effect of diode laser irradiation combined with topical fluoride on enamel surface microhardness.Forty-five primary teeth were used in this in vitro study. The teeth were sectioned to produce 90 slabs. The baseline Vickers microhardness number of each enamel surface was determined. The samples were randomly divided into 3 groups. Group 1: 5% NaF varnish, group 2: NaF varnish+ diode laser at 5 W power and group 3: NaF varnish+ diode laser at 7 W power. Then, the final microhardness number of each surface was again determined. The data were statistically analyzed by repeated measures ANOVA at 0.05 level of significance.In all 3 groups, microhardness number increased significantly after surface treatment (P0.05.The combined application of diode laser and topical fluoride varnish on enamel surface did not show any significant additional effect on enamel resistance to caries.
Micro-tensile bond strength of adhesive systems applied on occlusal primary enamel.
Ramires-Romito, Ana Cláudia; Reis, Alessandra; Loguercio, Alessandro Dourado; de Góes, Mario Fernando; Grande, Rosa Helena Miranda
2004-01-01
The aim of this study was to evaluate the micro-tensile bond strength of adhesive systems (OptiBond Solo, Kerr; Prime & Bond NT, Dentsply) on occlusal surface of primary molars. The adhesives were tested under manufacturers' specifications and after contamination of the bonding site with saliva. Hourglass cylindrical-shaped samples were obtained and subjected to a tensile force. No significant difference was observed among the groups. OptiBond Solo and Prime & Bond NT showed similar values of bond strengths when applied on occlusal enamel of primary molar under either saliva contamination or not.
Hosoya, Yumiko; Watanabe, Eiko; Tadokoro, Katsumi; Inoue, Takashi; Miyazaki, Masashi; Tay, Franklin R
2012-09-01
Silver diamine fluoride (Ag(NH(3))(2)F) arrests caries but stains teeth black. To overcome this drawback, we applied ammonium hexafluorosilicate (AHF; (NH(4))(2)SiF(6)) and observed changes in the color and structure of demineralized enamel and dentin of extracted primary teeth. Enamel and dentin were demineralized in 10% EDTA solution for 90 s followed by 35% phosphoric acid gel for 60 s, then soaked in AHF solution for 60 s. Before analysis by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS), enamel and dentin were demineralized in 10% EDTA for 90 s. Teeth were divided into 4 groups according to AHF application and artificial saliva immersion status and then examined. The data were statistically analyzed using one-way ANOVA and Fisher's PLSD test at a significance level of P F% and Ca/P ratio were significantly higher on dentin surfaces after AHF application without artificial saliva immersion. Further study on arresting caries treatment is required.
Analysis of the interface zone between the glass ionomer and enamel and dentin of primary molars
Petrović Bojan B.
2008-01-01
Full Text Available Restoring carious teeth is one of the major dental treatment needs of young children. Conventional glassionomer materials are frequently used as filling materials in contemporary pediatric dentistry. The objective of this study was to evaluate the restorative and prophylactic efficacy of the newly marketed glass ionomer, Fuji Triage (GC, Tokyo, Japan, through morphological analysis of the interface zone between the material and the enamel and the dentin of primary molars and to determine the extent of the ion exchange at the interface zone. The sample consisted of 5 extracted intact first primary molars in which glassionomer had been used as filling material after standard class I cavity preparation. The material was placed according to the manufacturer's instructions and teeth were placed into dionised water prior to experiment. Six sections of each tooth had been examined using scanning electron microscopic and electron dispersive spectroscopic techniques (SEM/EDS. The parameters for evaluation included: morphological characteristics of the interface zone and the extent of the ion exchange between the material and the tooth structures Results were statistically analyzed using descriptive statistical methods. SEM/EDS analysis revealed the presence of the chemical bonding between the glass ionomer and the enamel and dentin, 5 and 15 μm in width, respectively. Ion exchange has not been detected in the enamel at the EDS sensitivity level. Strontium and fluor penetration has been detected in dentin. The ion exchange and chemical bonding formation justify the usage of the conventional glass ionomer materials for restorative procedures in primary molars.
Memarpour, Mahtab; Soltanimehr, Elham; Sattarahmady, Naghmeh
2015-09-01
The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream, and 5) Clinpro White varnish containing functionalized tri-calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one-way ANOVA (pfluoride varnish (pfluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (pfluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP-ACP, toothpaste and fluoride varnish. The efficacy of CPP-ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish. © 2015 Wiley Periodicals, Inc.
Mahoney, Patrick; Miszkiewicz, Justyna J; Pitfield, Rosie; Schlecht, Stephen H; Deter, Chris; Guatelli-Steinberg, Debbie
2016-06-01
Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers-Halberg Oscillation hypothesis (HHO), Retzius periodicity (RP) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species' biology from fossilized teeth. Here, we tested intra-specific predictions of this hypothesis on skeletal samples of human juveniles. We measured daily enamel growth increments to calculate RP in deciduous molars (n = 25). Correlations were sought between RP, molar average and relative enamel thickness (AET, RET), and the average amount of primary bone growth (n = 7) in humeri of age-matched juveniles. Results show a previously undescribed relationship between RP and enamel thickness. Reduced major axis regression reveals RP is significantly and positively correlated with AET and RET, and scales isometrically. The direction of the correlation was opposite to HHO predictions as currently understood for human adults. Juveniles with higher RPs and thicker enamel had increased primary bone formation, which suggests a coordinating biorhythm. However, the direction of the correspondence was, again, opposite to predictions. Next, we compared RP from deciduous molars with new data for permanent molars, and with previously published values. The lowermost RP of 4 and 5 days in deciduous enamel extends below the lowermost RP of 6 days in permanent enamel. A lowered range of RP values in deciduous enamel implies that the underlying biorhythm might change with age. Our results develop the intra-specific HHO hypothesis. © 2016 Anatomical Society.
Success Evaluation of Pulpotomy in Primary Molars with Enamel Matrix Derivative: a Pilot Study
Fatemeh Mazhari
2016-06-01
Full Text Available Aim: To investigate the effect of Emdogain gel (EMD in pulpotomized primary molars and its clinical and radiographic outcomes. Methods and Materials: In this study, 18 lower second primary molars of nine children were treated by pulpotomy. The teeth were randomly assigned to the EMD (experimental and Formocresol (control groups in each patient (split mouth. Following removal of the coronal pulp and haemostasis, the pulp stumps were covered with Emdogain gel in the experimental group followed by application of resin-modified glass ionomer cement over the gel. In the control group, Formocresol (FC was placed with a cotton pellet over the pulp stumps. Lastly, the teeth in both groups were restored with stainless steel crowns. Results: Nine children referred with clinical failure before/at two months follow up. The radiographic evaluation revealed furcation involvement and extensive radicular radiolucency in molars treated with Emdogain gel. Conclusion: The present study showed the failure of enamel matrix derivative in pulpotomy of primary molars; therefore, we do not recommend using Emdogain as a pulpotomy agent for treatment of cariously exposed primary teeth
Knotted vs. unknotted proteins: evidence of knot-promoting loops.
Raffaello Potestio
Full Text Available Knotted proteins, because of their ability to fold reversibly in the same topologically entangled conformation, are the object of an increasing number of experimental and theoretical studies. The aim of the present investigation is to assess, on the basis of presently available structural data, the extent to which knotted proteins are isolated instances in sequence or structure space, and to use comparative schemes to understand whether specific protein segments can be associated to the occurrence of a knot in the native state. A significant sequence homology is found among a sizeable group of knotted and unknotted proteins. In this family, knotted members occupy a primary sub-branch of the phylogenetic tree and differ from unknotted ones only by additional loop segments. These "knot-promoting" loops, whose virtual bridging eliminates the knot, are found in various types of knotted proteins. Valuable insight into how knots form, or are encoded, in proteins could be obtained by targeting these regions in future computational studies or excision experiments.
Friedman, Greg
2004-01-01
This is an introduction to the construction of higher-dimensional knots by spinning methods. Simple spinning of classical knots was introduced by E. Artin in 1926, and several generalizations have followed. These include twist spinning, superspinning or p-spinning, frame spinning, roll spinning, and deform spinning. We survey these constructions and some of their most important applications, as well as some newer hybrids due to the author. The exposition, meant to be accessible to a broad aud...
Temperature rise during Er:YAG cavity preparation of primary enamel.
Contente, Marta Maria Martins Giamatei; de Lima, Fabrício Augusto; Galo, Rodrigo; Pécora, Jesus Djalma; Bachmann, Luciano; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina
2012-01-01
This study aimed to assess in vitro thermal alterations taking place during the Er:YAG laser cavity preparation of primary tooth enamel at different energies and pulse repetition rates. Forty healthy human primary molars were bisected in a mesio-distal direction, thus providing 80 fragments. Two small orifices were made on the dentin surface to which type K thermocouples were attached. The fragments were individually fixed with wax in a cylindrical Plexiglass® abutment and randomly assigned to eight groups, according to the laser parameters (n = 10): G1 - 250 mJ/ 3 Hz, G2 - 250 mJ/ 4 Hz, G3 - 250 mJ/ 6 Hz, G4 - 250 mJ/10 Hz, G5 - 250 mJ/ 15 Hz, G6 - 300 mJ/ 3 Hz, G7 - 300 mJ/ 4 Hz and G8 - 300 mJ/ 6 Hz. An area of 4 mm(2) was delimited. Cavities were done (2 mm long × 2 mm wide × 1 mm thick) using non-contact (12 mm) and focused mode. Temperature values were registered from the start of laser irradiation until the end of cavity preparation. Data were analyzed by one-way ANOVA and Tukey test (p ≤ 0.05). Groups G1, G2, G6, and G7 were statistically similar and furnished the lowest mean values of temperature rise. The set 250 mJ/10 and 15 Hz yielded the highest temperature values. The sets 250 and 300 mJ and 6 Hz provided temperatures with mean values below the acceptable critical value, suggesting that these parameters ablate the primary tooth enamel. Moreover, the temperature elevation was directly related to the increase in the employed pulse repetition rates. In addition, there was no direct correlation between temperature rise and energy density. Therefore, it is important to use a lower pulse frequency, such as 300 mJ and 6 Hz, during cavity preparation in pediatric patients.
R. A. Valério
2015-01-01
Full Text Available This study evaluated the effect of CO2 laser irradiation and topical fluoride therapy in the control of caries progression on primary teeth enamel. 30 fragments (3×3×2 mm from primary canines were submitted to an initial cariogenic challenge that consisted of immersion on demineralizing solution for 3 hours and remineralizing solution for 21 hours for 5 days. Fragments were randomly assigned into three groups (n=10: L: CO2 laser (λ=10.6 μm, APF: 1.23% acidulated phosphate fluoride, and C: no treatment (control. CO2 laser was applied with 0.5 W power and 0.44 J/cm2 energy density. Fluoride application was performed with 0.1 g for 1 minute. Cariogenic challenge was conducted for 5 days following protocol previously described. Subsurface Knoop microhardness was measured at 30 μm from the edge. Obtained data were subjected to analysis the variance (ANOVA and Duncan test with significance of 5%. It was found that the L group showed greater control of deciduous enamel demineralization and were similar to those of APF group, while being statistically different from C group (P≤0.05 that showed the lowest microhardness values. It was concluded that CO2 laser can be an additional resource in caries control progression on primary teeth enamel.
Enamel Matrix Derivative Promote Primary Human Pulp Cell Differentiation and Mineralization
Elisabeth Aurstad Riksen
2014-05-01
Full Text Available Enamel matrix derivative (EMD has been found to induce reactive dentin formation; however the molecular mechanisms involved are unclear. The effect of EMD (5–50 μg/mL on primary human pulp cells were compared to untreated cells and cells incubated with 10−8 M dexamethasone (DEX for 1, 2, 3, 7, and 14 days in culture. Expression analysis using Affymetrix microchips demonstrated that 10 μg/mL EMD regulated several hundred genes and stimulated the gene expression of proteins involved in mesenchymal proliferation and differentiation. Both EMD and DEX enhanced the expression of amelogenin (amel, and the dentinogenic markers dentin sialophosphoprotein (DSSP and dentin matrix acidic phosphoprotein 1 (DMP1, as well as the osteogenic markers osteocalcin (OC, BGLAP and collagen type 1 (COL1A1. Whereas, only EMD had effect on alkaline phosphatase (ALP mRNA expression, the stimulatory effect were verified by enhanced secretion of OC and COL1A from EMD treated cells, and increased ALP activity in cell culture medium after EMD treatment. Increased levels of interleukin-6 (IL-6, interleukin-8 (IL-8, and monocyte chemoattractant proteins (MCP-1 in the cell culture medium were also found. Consequently, the suggested effect of EMD is to promote differentiation of pulp cells and increases the potential for pulpal mineralization to favor reactive dentine formation.
Sakeenabi Basha
2016-01-01
Full Text Available Context: Enamel hypoplasia is a defect caused by disturbances during enamel formation. These defects in the enamel present important clinical significance as they predispose a tooth to dental caries. Aim: The aim of this study was to assess the longitudinal relationships between enamel hypoplasia and caries experience of primary second molars and permanent first molars. Materials and Methods: The study sample consisted of 765 subjects who underwent dental examinations at both ages 6 and 9 by the calibrated examiner. Primary second molars and permanent first molars were scored for the presence of enamel hypoplasia for each participant. Caries presence and number of decayed and filled surfaces (dfs and DFS were determined at ages 6 and 9. The relationships between enamel hypoplasia and caries experience were assessed using multivariable regression models. Results: At the tooth level, 2.8% and 3.5% of children had hypoplasia on primary second molars and permanent first molars respectively. Multivariable logistic regression analyses showed that children with enamel hypoplasia were at a significantly higher risk of caries at both ages 6 (odds ratio, OR = 5.27 for primary second molars and OR = 3.21 for permanent first molars and age 9 (OR = 3.45 for primary second molars and OR = 4.57 for permanent first molars, and that a statistically significant association was seen with caries incidence (OR = 2.08 for primary second molars and OR = 2.87 for permanent first molars. Conclusion: Enamel hypoplasia appears to be a significant risk factor for caries in both primary second molars and permanent first molars and should be considered in caries risk assessment.
Tooth enamel mineralization in ungulates: implications for recovering a primary isotopic time-series
Passey, Benjamin H.; Cerling, Thure E.
2002-09-01
Temporal changes in the carbon and oxygen isotopic composition of an animal are an environmental and behavioral input signal that is recorded into the enamel of developing teeth. In this paper, we evaluate changes in phosphorus content and density along the axial lengths of three developing ungulate teeth to illustrate the protracted nature of mineral accumulation in a volume of developing enamel. The least mature enamel in these teeth contains by volume about 25% of the mineral mass of mature enamel, and the remaining 75% of the mineral accumulates during maturation. Using data from one of these teeth (a Hippopotamus amphibius canine), we develop a model for teeth growing at constant rate that describes how an input signal is recorded into tooth enamel. The model accounts for both the temporal and spatial patterns of amelogenesis (enamel formation) and the sampling geometry. The model shows that input signal attenuation occurs as a result of time-averaging during amelogenesis when the maturation interval is long compared to the duration of features in the input signal. Sampling does not induce significant attenuation, provided that the sampling interval is several times shorter than the maturation interval. We present a detailed δ 13C and δ 18O record for the H. amphibius canine and suggest possible input isotope signals that may have given rise to the measured isotope signal.
Yimcharoen, Veeritta; Rirattanapong, Praphasri; Kiatchallermwong, Warawan
2011-07-01
This study evaluated the effect of a CPP-containing toothpaste and compared it with fluoride-containing toothpastes on remineralization of caries-like lesions in primary teeth enamel, using polarized light microscopy. Forty-eight sound primary incisors were coated with nail varnish, leaving two 1x1 mm windows before being placed in a demineralizing solution for 4 days. After demineralization, all the specimens were coated with nail varnish over one window and were randomly assigned to 4 groups (A to D; n = 12). Group A teeth were exposed to distilled water. Group B teeth were exposed to a CPP-containing toothpaste (Hi Herb). Group C teeth were exposed to a 260 ppm fluoride-containing toothpaste (Smile baby toothgel). Group D teeth were exposed to a 500 ppm fluoride-containing toothpaste (Oralmed Kid). Polarized light microscopy was used to evaluate lesion depth, before and after a 7-day pH cycle. Lesion depth was measured using a computerized method with the Image-Pro Plus program. Differences in mean lesion depth within groups and between groups were analysed using the paired t-test, Kruskal-Wallis test and Mann-Whitney U test at a 95% level of confidence. Mean lesion depths in Groups A, B, C and D significantly increased by 110.1, 36.1, 40.2 and 18.2%, respectively. The mean lesion depths for all the toothpaste groups (B, C and D) were significantly different from the control group (A). Comparisons made among treatment groups showed Group D was significantly different from Groups B and C. All toothpastes were effective for inhibiting progression of carious lesions. However, a 500 ppm fluoride-containing toothpaste inhibited lesion progression better than a CPP-containing toothpaste and a 260 ppm fluoride-containing toothpaste.
Ozgul, Betul Memis; Orhan, Kaan; Oz, Firdevs Tulga
2015-09-01
We investigated inhibition of lesion progression in artificial enamel lesions. Lesions were created on primary and permanent anterior teeth (n = 10 each) and were divided randomly into two groups with two windows: Group 1 (window A: resin infiltration; window B: negative control) and Group 2 (window A: resin infiltration + fluoride varnish; window B: fluoride varnish). After pH cycling, micro-computed tomography was used to analyze progression of lesion depth and changes in mineral density. Resin infiltration and resin infiltration + fluoride varnish significantly inhibited progression of lesion depth in primary teeth (P 0.05). Resin infiltration is a promising method of inhibiting progression of caries lesions.
Henrich, Allison; Narayan, Sneha; Pechenik, Oliver; Silversmith, Robert; Townsend, Jennifer
2010-01-01
In this paper, we introduce playing games on shadows of knots. We demonstrate two novel games, namely, To Knot or Not to Knot and Much Ado about Knotting. We also discuss winning strategies for these games on certain families of knot shadows. Finally, we suggest variations of these games for further study.
Willyanti Soewondo Sjarif
2013-06-01
Full Text Available Background: Prenatal disturbances disturb the development of organs resulting in small for gestational age (SGA babies and also causes enamel defects in primary teeth. There are disturbances occur in the beginning of pregnancy causing symmetrical SGA, and asymmetrical type of SGA, where the disturbances occur late in pregnancy. Purpose: This research was to determined differences in severity of enamel defect of primary dentition in small for gestational age children based on the time of intrauterine growth restriction. Methods: This was a clinical epidemiological cohort study. The Ponderal index was used to determine SGA type. The subjects were 129 SGA children aged 9-42 months, 82 with asymmetrical SGA and 47 with symmetrical SGA. Two hundred normal birth weight children were the control group. Intra-oral examinations to determine enamel defect used the FDI modification of the Developmental Defect of Enamel score at 3 months intervals. Statistical t-tests were used to test the difference in severity of enamel defect, and chisquare to find out the difference of Relative Risk Ratio (RRR. Results: The results showed that the enamel defect scores of symmetrical SGA were significantly higher than those with asymmetrical SGA. RRR for severe defect was also significantly higher in symmetrical type for anterior and canines. Conclusion: The study suggested that the severity of enamel defect for infants with symmetrical SGA was higher than those with asymmetrical SGA, indicating that the severity of the defect occurs in the beginning of pregnancy is more severe than in the late pregnancy.Latar belakang: Adanya gangguan prenatal mengganggu perkembangan organ, mengakibatkan terjadinya bayi lahir dengan kecil masa kehamilan (KMK dan defek email pada gigi sulung. Terdapat 2 tipe KMK yaitu tipe simetri; gangguan terjadi pada awal kehamilan; dimana lingkar kepala, berat dan panjang lahir lebih rendah dari normal. Tipe asimetri dimana gangguan terjadi saat
Tuloglu, Nuray; Bayrak, Sule; Tunc, Emine Sen; Ozer, Fusun
2016-09-26
This study aimed to investigate the effects of a fluoride varnish with added Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) treatments on acid resistance of primary teeth enamel. Enamel specimens obtained from 40 primary incisors (for surface microhardness testing) and 40 primary molars (for demineralization depth measurement) were randomly divided into four groups (n = 10 incisors and 10 molars) each according to surface treatment: no treatment (control), MI varnish (1-8 % sodium fluoride and 1-5 % CPP-ACP), Clinpro White (1-5 % sodium fluoride and fluoride). Specimens were stored for 24 h in a moist environment. After varnish residues were removed, specimens were subjected to pH cycling. The effects of fluoride varnishes were evaluated according to surface microhardness, lesion depth and structural changes. Results were analyzed by ANOVA and Tukey's tests. The lowest changes in surface microhardness and lesion depth occurred in MI varnish group, followed by the Clinpro White, Duraphat and no treatment (control) group (for percentage of loss surface microhardness -20.80, -34.60, -57.80 and -73.40; for lesion depth values 23.60 μm ± 3.36, 29.85 μm ± 3.27, 40.37 μm ± 3.41 and 54.56 μm ± 4.16, respectively). Statistically significant differences in both surface microhardness and lesion depth were observed among all groups (P fluoride varnish containing CPP-ACP was more effective in increasing the acid resistance of primary enamel than other fluoride varnishes. However, further clinical research is needed to confirm these in vitro results.
Suzan Sahana
2013-01-01
Full Text Available Background: It is axiomatic that Pediatric dental anomalies and enamel hypoplasia (E.H are routinely encountered in primary dentition and early detection and prudent management of the condition facilitates normal occlusal development. Objectives: To determine the prevalence of various dental anomalies and enamel hypoplasia in preschool children between two to six years of age. Materials & Method: A total of 1898 children, between two to six years were randomly selected and screened for dental anomalies and enamel hypoplasia The chi square test was used to analyze the data statistically. Results: The overall prevalence rate of dental anomalies and enamel hypoplasia in this study was 0.63% and 8.95% respectively. Double teeth were the most frequently reported dental anomaly while supernumerary teeth were least reported. None of them reported with hypodontia.
Sri Candiana Harahap
2008-01-01
Mottled enamel (enamel fluorosis, dental fluorosis) adalah salah satu bentuk dari hipoplasia enamel yaitu berupa berkurangnya jumlah matriks pembentuk enamel akibat adanya gangguan pada ameloblas selama tahap formatif perkembangan gigi, yang terjadi baik pada gigi desidui maupun gigi permanen. Penyebab terjadinya mottled enamel adalah fluorosis yaitu masuknya fluor dengan konsentrasi yang tinggi kedalam tubuh baik secara sistemik dan, atau lokal hingga mencapai > Ippm F. Gam...
Practical and ornamental knots
Shaw, George Russell
2008-01-01
For centuries, everyone from sailors, fishermen, and cowboys to explorers, hunters, and mountaineers have known about - and relied on - the indispensable knot. Many of them also knew that the diversity of knot crafting was limited only by the imagination. In this classic guide, George Russell Shaw reveals the unlimited potential of the knot as not only a basic tool, but as a beautiful work of art.Filled with easy-to-follow and accurate instructions on creating scores of useful and decorative knots, 193 hand-drawn illustrations will guide you in creating: Braids Angler Knots Japanese Knots L
Yacov Kantov
2005-06-01
Knots and topological entanglements play an important role in the statistical mechanics of polymers. While topological entanglement is a global property, it is possible to study the size of a knotted region both numerically and analytically. It can be shown that long-range repulsive interactions, as well as entropy favor small knots in dilute systems. However, in dense systems and at the -point in two dimensions the uncontracted knot configuration is the most likely.
p38α MAPK Is Required for Tooth Morphogenesis and Enamel Secretion*
Greenblatt, Matthew B.; Kim, Jung-Min; Oh, Hwanhee; Park, Kwang Hwan; Choo, Min-Kyung; Sano, Yasuyo; Tye, Coralee E.; Skobe, Ziedonis; Davis, Roger J.; Park, Jin Mo; Bei, Marianna; Glimcher, Laurie H.; Shim, Jae-Hyuck
2015-01-01
An improved understanding of the molecular pathways that drive tooth morphogenesis and enamel secretion is needed to generate teeth from organ cultures for therapeutic implantation or to determine the pathogenesis of primary disorders of dentition (Abdollah, S., Macias-Silva, M., Tsukazaki, T., Hayashi, H., Attisano, L., and Wrana, J. L. (1997) J. Biol. Chem. 272, 27678–27685). Here we present a novel ectodermal dysplasia phenotype associated with conditional deletion of p38α MAPK in ectodermal appendages using K14-cre mice (p38αK14 mice). These mice display impaired patterning of dental cusps and a profound defect in the production and biomechanical strength of dental enamel because of defects in ameloblast differentiation and activity. In the absence of p38α, expression of amelogenin and β4-integrin in ameloblasts and p21 in the enamel knot was significantly reduced. Mice lacking the MAP2K MKK6, but not mice lacking MAP2K MKK3, also show the enamel defects, implying that MKK6 functions as an upstream kinase of p38α in ectodermal appendages. Lastly, stimulation with BMP2/7 in both explant culture and an ameloblast cell line confirm that p38α functions downstream of BMPs in this context. Thus, BMP-induced activation of the p38α MAPK pathway is critical for the morphogenesis of tooth cusps and the secretion of dental enamel. PMID:25406311
Sabbarini, Jumana; Mohamed, Ahmed; Wahba, Nadia; El-Meligy, Omar; Dean, Jeffrey
2008-03-01
The purpose of this study was to compare the clinical and radiographic success rates of two different pulpotomy agents: one novel agent, the biologically active odontogenic protein enamel matrix derivative (EMD) versus formocresol (FC). A randomized, single-blind, split-mouth study was used with a sample of 15 children aged 4 to 7 years (mean age, 5 +/- 0.73 years). A total of 15 pairs of teeth, 1 pair per child, were selected for treatment. One tooth from each pair was randomly assigned to either the EMD pulpotomy group or the FC pulpotomy group. All teeth were followed up clinically and radiographically at 2, 4, and 6 months. After 6 months, the clinical success rates for the FC and EMD groups were 67% and 93%, respectively. Although most likely clinically relevant, the clinical success rate difference after 6 months was not statistically significant. After 6 months, the radiographic success rates for the FC and EMD groups were 13% and 60 %, respectively. There was a statistically significant difference at p < or = 0.05. The clinical and radiographic assessment of EMD pulpotomized teeth in this study offers preliminary evidence that EMD is a promising material which may be as successful, or more so, than other pulpotomy agents.
Rolfsen, Dale
2003-01-01
Rolfsen's beautiful book on knots and links can be read by anyone, from beginner to expert, who wants to learn about knot theory. Beginners with a basic background find an inviting introduction to the elements of topology, emphasizing the tools needed for understanding knots, the fundamental group and van Kampen's theorem, for example, which are then applied to concrete problems, such as computing knot groups. For experts, Rolfsen explains advanced topics, such as the connections between knot theory and surgery and how they are useful to understanding three-manifolds. Besides providing a guide
Menasco, William
2005-01-01
This book is a survey of current topics in the mathematical theory of knots. For a mathematician, a knot is a closed loop in 3-dimensional space: imagine knotting an extension cord and then closing it up by inserting its plug into its outlet. Knot theory is of central importance in pure and applied mathematics, as it stands at a crossroads of topology, combinatorics, algebra, mathematical physics and biochemistry.* Survey of mathematical knot theory* Articles by leading world authorities* Clear exposition, not over-technical* Accessible to readers with undergraduate background in mathematics
Nozari A.
2011-05-01
Full Text Available Statement of Problem: Dental erosion is defined as the loss of tooth substance by chemical processes not involving bacteria. Dental erosion has been found to be a common cause of tooth wear. Clinically apparent erosion has been found to be related to dietary factors such as the acid content of the beverages.Purpose: Evaluation of enamel erosion in the primary and permanent teeth as the result of two most common acidic drinks produced in Iranian factories, Mirinda and Pepsi.Materials and Method: The outermost surfaces of 20 primary and 20 permanent teeth were polished flat by using the finest grade sandpaper and water in order to facilitate the proper measurement. The specimens were then prepared by cutting 3-4 mm of the buccal surface of teeth by diamond burs. The specimens were then rinsed with distilled water and stored in 100˚10 humidity before testing. The surface micro-hardness of each specimen was measured by micro vickers Hardness tester before, after 5 minutes, and 10 minutes exposure to fresh solution of each drink (10 teeth per test group. Mann-Whitney and Wilcoxon signed rank tests were used for the estatistical analysis.Results: The results showed that both drinks, Mirinda and Pepsi, produced significant surface hardness loss at 5 and 10 minutes of exposure time ( p =0.05. The amount of erosive effect was changed as the exposure time increased (change from 5 to 10 minutes. There was no statistically significant difference between the amounts of surface hardness loss in the primary and permanent enamel ( p >0.05. Conclusion: Both drinks may have almost similar but significant erosive effect on the primary and permanent enamel surfaces. Although there wasn’t any difference between erosive effect of the two beverages, this effect was increased with increase in time. The primary teeth enamel was not found to be more susceptibe to acidic beverage-induced erosion than the permanent teeth.
Yildirim, Ceren; Basak, Feridun; Akgun, Ozlem Marti; Polat, Gunseli Guven; Altun, Ceyhan
2016-01-01
The aim of this study was to evaluate and to compare clinical and radiographic outcomes of 4 materials (formocresol, mineral trioxide aggregate (MTA), Portland cement and enamel matrix derivative) using in primary teeth pulpotomies. Sixty-five patients aged 5-9 years (32 female, 33 male) were included in this study. A total of 140 primary first and second molars with deep caries were treated with pulpotomy. All teeth were then restored with stainless steel crowns. The treated teeth were evaluated clinically and radiographically at 3, 6, 12, 18 and 24 months. At 24 months, the clinical success rates of formocresol, MTA, Portland cement, and enamel matrix derivative were 96.9%, 100%, 93.9%, and 93.3%, respectively. The corresponding radiographic success rates were 84.4%, 93.9%, 86.7% and 78.1%, respectively. Although there were no statistically significant differences in clinical and radiographic success rates among the 4 groups, MTA appears to be superior to formocresol, Portland cement, and enamel matrix derivative as a pulpotomy agent in primary teeth.
Tabulating knot polynomials for arborescent knots
Mironov, A; Morozov, An; Sleptsov, A; Ramadevi, P; Singh, Vivek Kumar
2016-01-01
Arborescent knots are the ones which can be represented in terms of double fat graphs or equivalently as tree Feynman diagrams. This is the class of knots for which the present knowledge is enough for lifting topological description to the level of effective analytical formulas. The paper describes the origin and structure of the new tables of colored knot polynomials, which will be posted at the dedicated site. Even if formal expressions are known in terms of modular transformation matrices, the computation in finite time requires additional ideas. We use the "family" approach, and apply it to arborescent knots in Rolfsen table by developing a Feynman diagram technique, associated with an auxiliary matrix model field theory. Gauge invariance in this theory helps to provide meaning to Racah matrices in the case of non-trivial multiplicities and explains the need for peculiar sign prescriptions in the calculation of [21]-colored HOMFLY polynomials.
Enamel matrix derivative promote primary human pulp cell differentiation and mineralization
Riksen, Elisabeth Aurstad; Landin, Maria A; Reppe, Sjur; Nakamura, Yukio; Lyngstadaas, Ståle Petter; Reseland, Janne E
2014-01-01
...; however the molecular mechanisms involved are unclear. The effect of EMD (5-50 μg/mL) on primary human pulp cells were compared to untreated cells and cells incubated with 10⁻⁸ M dexamethasone (DEX...
Microtensile bond strength of sealant and adhesive systems applied to occlusal primary enamel
Ramires-Romito, ACD; Reis, A; Loguercio, AD; Hipolito, VD; de Goes, MF; Singer, JD; Grande, RHM
2007-01-01
Purpose: To compare the microtensile bond strength (mu TBS) of a self-etch adhesive system (OptiBond Solo Self-Etch Adhesive System), two total etch adhesive system (OptiBond FL; OptiBond Solo), and a conventional sealant (Clinpro) applied to the occlusal surface of primary molars under saliva contamination. Methods: Sealant and adhesive systems were applied under manufacturers' specifications with or without previous saliva contamination. After storage in distilled water at 37 degrees C for ...
Turner, J C
1996-01-01
This book brings together twenty essays on diverse topics in the history and science of knots. It is divided into five parts, which deal respectively with knots in prehistory and antiquity, non-European traditions, working knots, the developing science of knots, and decorative and other aspects of knots.Its authors include archaeologists who write on knots found in digs of ancient sites (one describes the knots used by the recently discovered Ice Man); practical knotters who have studied the history and uses of knots at sea, for fishing and for various life support activities; a historian of l
Zou, L P; Pak, D G
2013-01-01
We consider topological structure of classical vacuum solutions in quantum chromodynamics. Topologically non-equivalent vacuum configurations are classified by non-trivial second and third homotopy groups for coset of the color group SU(N) (N=2,3) under the action of maximal Abelian stability group. Starting with explicit vacuum knot configurations we study possible exact classical solutions as vacuum excitations. Exact analytic non-static knot solution in a simple CP^1 model in Euclidean space-time has been obtained. We construct an ansatz based on knot and monopole topological vacuum structure for searching new solutions in SU(2) and SU(3) QCD. We show that singular knot-like solutions in QCD in Minkowski space-time can be naturally obtained from knot solitons in integrable CP^1 models. A family of Skyrme type low energy effective theories of QCD admitting exact analytic solutions with non-vanishing Hopf charge is proposed.
The Wiese Knot: A Sliding-Locking Arthroscopic Knot.
Parada, Stephen A; Shaw, K Aaron; Eichinger, Josef K; Boykin, Nathan T; Gloystein, David M; Ledford, Cheryl L; Arrington, Edward D; Wiese, Paul T
2017-02-01
Despite recent advances in knotless suture devices for arthroscopic surgical procedures, arthroscopic knot tying remains a necessary skill for the arthroscopic surgeon. Successful completion of arthroscopic knot tying relies on a thorough understanding of the chosen technique, proper suture management, adequate knot tensioning and securement, and the ability to reproducibly create the knot. We introduce a technique that serves as both a sliding and locking knot while being simple to master and reproducible to perform.
Tabulating knot polynomials for arborescent knots
Mironov, A.; Morozov, A.; Morozov, A.; Ramadevi, P.; Singh, Vivek Kumar; Sleptsov, A.
2017-02-01
Arborescent knots are those which can be represented in terms of double fat graphs or equivalently as tree Feynman diagrams. This is the class of knots for which the present knowledge is sufficient for lifting topological description to the level of effective analytical formulas. The paper describes the origin and structure of the new tables of colored knot polynomials, which will be posted at the dedicated site (http://knotebook.org). Even if formal expressions are known in terms of modular transformation matrices, the computation in finite time requires additional ideas. We use the ‘family’ approach, suggested in Mironov and Morozov (2015 Nucl. Phys. B 899 395–413), and apply it to arborescent knots in the Rolfsen table by developing a Feynman diagram technique, associated with an auxiliary matrix model field theory. Gauge invariance in this theory helps to provide meaning to Racah matrices in the case of non-trivial multiplicities and explains the need for peculiar sign prescriptions in the calculation of [21]-colored HOMFLY-PT polynomials.
2011-01-01
Statement of Problem: Dental erosion is defined as the loss of tooth substance by chemical processes not involving bacteria. Dental erosion has been found to be a common cause of tooth wear. Clinically apparent erosion has been found to be related to dietary factors such as the acid content of the beverages.Purpose: Evaluation of enamel erosion in the primary and permanent teeth as the result of two most common acidic drinks produced in Iranian factories, Mirinda and Pepsi.Materials and Meth...
Combinatorial Maps with Normalized Knot
Zeps, Dainis
2010-01-01
We consider combinatorial maps with fixed combinatorial knot numbered with augmenting numeration called normalized knot. We show that knot's normalization doesn't affect combinatorial map what concerns its generality. Knot's normalization leads to more concise numeration of corners in maps, e.g., odd or even corners allow easy to follow distinguished cycles in map caused by the fixation of the knot. Knot's normalization may be applied to edge structuring knot too. If both are normalized then one is fully and other partially normalized mutually.
Banagl, Markus
2011-01-01
The present volume grew out of the Heidelberg Knot Theory Semester, organized by the editors in winter 2008/09 at Heidelberg University. The contributed papers bring the reader up to date on the currently most actively pursued areas of mathematical knot theory and its applications in mathematical physics and cell biology. Both original research and survey articles are presented; numerous illustrations support the text. The book will be of great interest to researchers in topology, geometry, and mathematical physics, graduate students specializing in knot theory, and cell biologists interested
Nawata, Satoshi
2015-01-01
We provide various formulations of knot homology that are predicted by string dualities. In addition, we also explain the rich algebraic structure of knot homology which can be understood in terms of geometric representation theory in these formulations. These notes are based on lectures in the workshop "Physics and Mathematics of Link Homology" at Centre de Recherches Math\\'ematiques, Universit\\'e de Montr\\'eal.
Aneziris, Charilaos N
1999-01-01
One of the most significant unsolved problems in mathematics is the complete classification of knots. The main purpose of this book is to introduce the reader to the use of computer programming to obtain the table of knots. The author presents this problem as clearly and methodically as possible, starting from the very basics. Mathematical ideas and concepts are extensively discussed, and no advanced background is required.
Proteins analysed as virtual knots
Alexander, Keith; Dennis, Mark R
2016-01-01
Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identify...
Honda, Masaki J; Shinmura, Yuka; Shinohara, Yoshinori
2009-01-01
We describe a strategy for the in vitro engineering of enamel tissue using a novel technique for culturing enamel organ epithelial (EOE) cells isolated from the enamel organ using 3T3-J2 cells as a feeder layer. These subcultured EOE cells retain the capacity to produce enamel structures over a period of extended culture. In brief, enamel organs from 6-month-old porcine third molars were dissociated into single cells and subcultured on 3T3-J2 feeder cell layers. These subcultured EOE cells were then seeded onto a collagen sponge in combination with primary dental pulp cells isolated at an early stage of crown formation, and these constructs were transplanted into athymic rats. After 4 weeks, complex enamel-dentin structures were detected in the implants. These results show that our culture technique maintained ameloblast lineage cells that were able to produce enamel in vivo. This novel subculture technique provides an important tool for tooth tissue engineering.
Rational-slice Knots via Strongly Negative-amphicheiral Knots
KAWAUCHI AKIO
2009-01-01
We show that certain satellite knots of every strongly negative-amphicheiral rational knot are rational-slice knots. This proof also shows that the 0-surgery man-ifold of a certain strongly negative amphicheiral knot such as the figure-eight knot bounds a compact oriented smooth 4-manifold homotopy equivalent to the 2-sphere such that a second homology class of the 4-manifold is represented by a smoothly embedded 2-sphere if and only if the modulo two reduction of it is zero.
Knot theory in modern chemistry.
Horner, Kate E; Miller, Mark A; Steed, Jonathan W; Sutcliffe, Paul M
2016-11-21
Knot theory is a branch of pure mathematics, but it is increasingly being applied in a variety of sciences. Knots appear in chemistry, not only in synthetic molecular design, but also in an array of materials and media, including some not traditionally associated with knots. Mathematics and chemistry can now be used synergistically to identify, characterise and create knots, as well as to understand and predict their physical properties. This tutorial review provides a brief introduction to the mathematics of knots and related topological concepts in the context of the chemical sciences. We then survey the broad range of applications of the theory to contemporary research in the field.
Sedimentation of Knotted Polymers
Piili, Joonas; Kaski, Kimmo; Linna, Riku
2012-01-01
We investigate the sedimentation of knotted polymers by means of the stochastic rotation dynamics, a molecular dynamics algorithm which takes hydrodynamics fully into account. We show that the sedimentation coefficient s, related to the terminal velocity of the knotted polymers, increases linearly with the average crossing number n_c of the corresponding ideal knot. To the best of our knowledge, this provides the first direct computational confirmation of this relation, postulated on the basis of experiments in "The effect of ionic conditions on the conformations of supercoiled DNA. I. sedimentation analysis" by Rybenkov et al., for the case of sedimentation. Such a relation was previously shown to hold with simulations for knot electrophoresis. We also show that there is an accurate linear dependence of s on the inverse of the radius of gyration R_g^-1, more specifically with the inverse of the R_g component that is perpendicular to the direction along which the polymer sediments. Intriguingly, the linear de...
Dental enamel cells express functional SOCE channels.
Nurbaeva, Meerim K; Eckstein, Miriam; Concepcion, Axel R; Smith, Charles E; Srikanth, Sonal; Paine, Michael L; Gwack, Yousang; Hubbard, Michael J; Feske, Stefan; Lacruz, Rodrigo S
2015-10-30
Dental enamel formation requires large quantities of Ca(2+) yet the mechanisms mediating Ca(2+) dynamics in enamel cells are unclear. Store-operated Ca(2+) entry (SOCE) channels are important Ca(2+) influx mechanisms in many cells. SOCE involves release of Ca(2+) from intracellular pools followed by Ca(2+) entry. The best-characterized SOCE channels are the Ca(2+) release-activated Ca(2+) (CRAC) channels. As patients with mutations in the CRAC channel genes STIM1 and ORAI1 show abnormal enamel mineralization, we hypothesized that CRAC channels might be an important Ca(2+) uptake mechanism in enamel cells. Investigating primary murine enamel cells, we found that key components of CRAC channels (ORAI1, ORAI2, ORAI3, STIM1, STIM2) were expressed and most abundant during the maturation stage of enamel development. Furthermore, inositol 1,4,5-trisphosphate receptor (IP3R) but not ryanodine receptor (RyR) expression was high in enamel cells suggesting that IP3Rs are the main ER Ca(2+) release mechanism. Passive depletion of ER Ca(2+) stores with thapsigargin resulted in a significant raise in [Ca(2+)]i consistent with SOCE. In cells pre-treated with the CRAC channel blocker Synta-66 Ca(2+) entry was significantly inhibited. These data demonstrate that enamel cells have SOCE mediated by CRAC channels and implicate them as a mechanism for Ca(2+) uptake in enamel formation.
Saeed Aedha AlAmoudi
2013-01-01
Full Text Available Aim. The aim of this study was to compare the effect of pH cycling on the microhardness of the enamel of primary human teeth treated with a conventional brown Sodium Fluoride (5% NaF Varnish to those treated with a white Fluoride Varnish (5% NaF enhanced with functionalized tricalcium phosphate (fTCP. Materials and Methods. Ninety extracted caries-free primary incisors were washed in a detergent and divided into three groups; group A received no treatment, teeth in group B were coated with Sodium Fluoride (5% NaF Varnish, while teeth in group C were coated with 5% NaF varnish enhanced with functionalized tricalcium phosphate (fTCP. After ten days of pH cycling, the surface microhardness of the teeth was measured using a Knoop indenter. Results. The mean Knoop hardness number (KHN of 5% NaF with fTCP was greater than that of 5% NaF alone while the control group had the lowest mean KHN. Conclusion. The results of this study suggest that the use of an additive such as fTCP to a fluoride varnish significantly improves the protective ability of the varnish on primary teeth in vitro.
Proteins analysed as virtual knots
Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.
2017-02-01
Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important.
Proteins analysed as virtual knots
Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.
2017-01-01
Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important. PMID:28205562
Determining Knots by Minimizing Energy
Cai-Ming Zhang; Hui-Jian Han; Fuhua Frank Cheng
2006-01-01
A new method for determining knots to construct polynomial curves is presented. At each data point, a quadric curve which passes three consecutive points is constructed. The knots for constructing the quadric curve are determined by minimizing the internal strain energy, which can be regarded as a function of the angle. The function of the angle is expanded as a Taylor series with two terms, then the two knot intervals between the three consecutive points are defined by linear expression. Between the two consecutive points, there are two knot intervals, and the combination of the two knot intervals is used to define the final knot interval. A comparison of the new method with several existing methods is included.
Knot probabilities in random diagrams
Cantarella, Jason; Chapman, Harrison; Mastin, Matt
2016-10-01
We consider a natural model of random knotting—choose a knot diagram at random from the finite set of diagrams with n crossings. We tabulate diagrams with 10 and fewer crossings and classify the diagrams by knot type, allowing us to compute exact probabilities for knots in this model. As expected, most diagrams with 10 and fewer crossings are unknots (about 78% of the roughly 1.6 billion 10 crossing diagrams). For these crossing numbers, the unknot fraction is mostly explained by the prevalence of ‘tree-like’ diagrams which are unknots for any assignment of over/under information at crossings. The data shows a roughly linear relationship between the log of knot type probability and the log of the frequency rank of the knot type, analogous to Zipf’s law for word frequency. The complete tabulation and all knot frequencies are included as supplementary data.
Bajaj, Meghna; Poornima, P; Praveen, S; Nagaveni, N B; Roopa, K B; Neena, I E; Bharath, K P
To compare CPP-ACP, Tri-calcium phosphate and Hydroxyapatite on remineralization of artificial caries like lesions on primary enamel. Ten extracted Primary molars coated with nail varnish, leaving a window of 2×4 mm on buccal and lingual surface were immersed in demineralizing solution for 96 hours and sectioned longitudinally to obtain 40 sections (4 sections per tooth) and were randomly divided into 4 groups (A to D) n=10; Group A: negative control, Group B: CPP-ACP, Group C: Tri-calcium phosphate, Group D: Hydroxyapatite. Sections were subjected to pH cycling for 10 days and were evaluated by polarized light microscope before and after treatment. Intra group comparison of demineralization and remineralization was done by paired t-test. One way ANOVA was used for multiple group comparisons followed by post HOC TUKEY'S Test for group wise comparisons. Remineralization was found more with Group D followed by Group B, C and A. Hydroxyapatite showed better remineralization when compared to CPP-ACP and Tri-calcium phosphate.
Untangling of knotted urethral catheters
Sambrook, Andrew J. [Aberdeen Royal Infirmary, Department of Radiology, Aberdeen (United Kingdom); Todd, Alistair [Raigmore Hospital, Inverness (United Kingdom)
2007-04-15
Intravesical catheter knotting during micturating cystourethrography is a rare but recognized complication of the procedure. We were able to untangle a knot utilizing a fluoroscopically guided vascular guidewire. Following this success, a small study was performed using a model. Various types of guidewires and techniques were tested for different diameters of knots in order to predict the likelihood of success in this type of situation. (orig.)
Untangling of knotted urethral catheters.
Sambrook, Andrew J; Todd, Alistair
2007-04-01
Intravesical catheter knotting during micturating cystourethrography is a rare but recognized complication of the procedure. We were able to untangle a knot utilizing a fluoroscopically guided vascular guidewire. Following this success, a small study was performed using a model. Various types of guidewires and techniques were tested for different diameters of knots in order to predict the likelihood of success in this type of situation.
Plasma fluoride and enamel fluorosis.
Angmar-Månsson, B; Ericsson, Y; Ekberg, O
1976-11-24
It is postulated that tissue fluid F concentrations are the primary determinants of flouride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 muM in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed.
Enamel pearl on an unusual location associated with localized periodontal disease: A clinical report
2013-01-01
Bacterial plaque has been implicated as the primary etiologic factor in the initiation and progression of periodontal disease. Anatomic factors (such as enamel pearls) are often associated with advanced localized periodontal destruction. The phenomenon of ectopic development of enamel on the root surface, variedly referred to as enameloma, enamel pearl, enamel drop or enamel nodule, is not well-understood. Such an anomaly may facilitate the progression of periodontal breakdown. A rare case of...
Naughty knot: a case of nasogastric tube knotting.
Ravind, Rahul; Prameela, Chelakkot G; Gurram, Bharath Chandra; Dinesh, Makuny
2015-10-13
Nasogastric intubation is a common procedure for enteral nutritional support in medical practice. Random spontaneous true knot formation in the tube is rarely encountered and is a cause of unanticipated trauma. This is a case of a true knot formation diagnosed with fluoroscopy and managed without untoward trauma.
How superfluid vortex knots untie
Kleckner, Dustin; Kauffman, Louis H.; Irvine, William T. M.
2016-07-01
Knots and links often occur in physical systems, including shaken strands of rope and DNA (ref. ), as well as the more subtle structure of vortices in fluids and magnetic fields in plasmas. Theories of fluid flows without dissipation predict these tangled structures persist, constraining the evolution of the flow much like a knot tied in a shoelace. This constraint gives rise to a conserved quantity known as helicity, offering both fundamental insights and enticing possibilities for controlling complex flows. However, even small amounts of dissipation allow knots to untie by means of `cut-and-splice’ operations known as reconnections. Despite the potentially fundamental role of these reconnections in understanding helicity--and the stability of knotted fields more generally--their effect is known only for a handful of simple knots. Here we study the evolution of 322 elemental knots and links in the Gross-Pitaevskii model for a superfluid, and find that they universally untie. We observe that the centreline helicity is partially preserved even as the knots untie, a remnant of the perfect helicity conservation predicted for idealized fluids. Moreover, we find that the topological pathways of untying knots have simple descriptions in terms of minimal two-dimensional knot diagrams, and tend to concentrate in states which are twisted in only one direction. These results have direct analogies to previous studies of simple knots in several systems, including DNA recombination and classical fluids. This similarity in the geometric and topological evolution suggests there are universal aspects in the behaviour of knots in dissipative fields.
Mineralization potential of polarized dental enamel.
Reina Tanaka
Full Text Available BACKGROUND: Management of human teeth has moved from a surgical to a more conservative approach of inhibiting or preventing lesion progression. Increasing enamel mineralization is crucial in this regard. A potential difficulty is the preferential mineralization of the outermost portion of the enamel that can prevent overall mineralization. We describe a strategy for increasing the mineralization potential of dental enamel. METHODOLOGY/PRINCIPAL FINDINGS: Extracted human premolar teeth enamel (n = 5 were exposed to a high concentration of hydrogen peroxide with an energizing source. Samples were stored in artificial saliva at 37 degrees C for 1 wk. A desktop X-ray micro-CT system was used to evaluate the mineral density of samples. Mineral distribution was polarized between the lower and the higher mineralized portion of enamel by charged oxygen free radicals due to activation of permeated hydrogen peroxide. The kinetics of energy absorption in the deeper enamel region demonstrated improvement of preferential mineralization into the region without restricting overall mineralization of the enamel. Subsequent increasing mineralization, even in the dense mineralized outer portion of enamel, was also achieved. CONCLUSIONS/SIGNIFICANCE: This increased mineralization may promote resistance to acidic deterioration of the structure. The present study is one of the primary steps towards the development of novel application in reparative and restorative dentistry.
On knots in overtwisted contact structures
Etnyre, John B
2010-01-01
We prove that each overtwisted contact structure has knot types that are represented by infinitely many distinct transverse knots all with the same self-linking number. In some cases, we can even classify all such knots. We also show similar results for Legendrian knots and prove a "folk" result concerning loose transverse and Legendrian knots (that is knots with overtwisted complements) which says that such knots are determined by their classical invariants (up to contactomorphism). Finally we discuss how these results partially fill in our understanding of the "geography" and "botany"' problems for Legendrian knots in overtwisted contact structures, as well as many open questions regarding these problems.
Zhao, Xin
2013-05-01
Elastic rods have been studied intensively since the 18th century. Even now the theory of elastic rods is still developing and enjoying popularity in computer graphics and physical-based simulation. Elastic rods also draw attention from architects. Architectural structures, NODUS, were constructed by elastic rods as a new method of form-finding. We study discrete models of elastic rods and NODUS structures. We also develop computational tools to find the equilibria of elastic rods and the shape of NODUS. Applications of elastic rods in forming torus knot and closing Bishop frame are included in this thesis.
Nullification of knots and links
Diao, Yuanan; Montemayor, Anthony
2011-01-01
In this paper, we study a geometric/topological measure of knots and links called the nullification number. The nullification of knots/links is believed to be biologically relevant. For example, in DNA topology, one can intuitively regard it as a way to measure how easily a knotted circular DNA can unknot itself through recombination of its DNA strands. It turns out that there are several different ways to define such a number. These definitions lead to nullification numbers that are related, but different. Our aim is to explore the mathematical properties of these nullification numbers. First, we give specific examples to show that the nullification numbers we defined are different. We provide detailed analysis of the nullification numbers for the well known 2-bridge knots and links. We also explore the relationships among the three nullification numbers, as well as their relationships with other knot invariants. Finally, we study a special class of links, namely those links whose general nullification numbe...
林小波; 张笋; 吴卫红; 吴志文
2011-01-01
目的 研究早产因素对脑瘫儿童乳牙釉质发育缺陷的影响.方法 选择135名脑瘫患儿,与62名正常儿童对比,进行乳牙釉质发育缺陷状况的统计调查.同时比较脑瘫儿童中早产与乳牙釉质发育缺陷发生的关系.结果 脑瘫儿童组中早产儿童乳牙釉质发育缺陷的患病率明显高于足月组,有统计学差异(P<0.05).结论 早产的脑瘫儿童更容易发生乳牙釉质发育缺陷.%Objective To investigate the developmental enamel defects in the primary dentition of cerebral palsied children with premature birth. Methods One hundred and thirty-five children with cerebral palsy were examined for the clinical manifestation of the developmental enamel defects in the primary dentition. The relationship between the defects and cerebral palsied children's birth conditions were assessed. Results The prevalence of enamel defects in cerebral palsied children born premarurely was significantly higher than that in those with full term birth. Conclusion Enamel defects in the primary dentition are more likely to happen in cerebral palsied children with premature birth than those with full term birth.
Arrayás, M.; Bouwmeester, D.; Trueba, J. L.
2017-01-01
Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless
Mechanical Normal Forms of Knots and Flat Knots
Sossinsky, A B
2010-01-01
A new type of knot energy is presented via real life experiments involving a thin resilient metallic tube. Knotted in different ways, the device mechanically acquires a uniquely determined (up to isometry) normal form at least when the original knot diagram has a small number of crossings, thus outperforming the famous M\\"obius energy due to Jun O'Hara and studied by Michael Freedman et al. Various properties of the device are described (under certain conditions it does the Reidemeister and Markov moves, it beautifully performs the Whitney trick by uniformizing its own local curvature). If the device is constrained between two parallel planes (e.g. glass panes), it yields a real life model of a flat knot (class of knot diagrams equivalent under Reidemeister $\\Omega_2$ and $\\Omega_3$ moves) also leading to uniquely determined "flat normal forms" (for a small number of crossing points of the given flat knot diagram). The paper concludes with two mathematical theorems, one reducing the knot recognition problem t...
Amelogenin and Enamel Biomimetics
Ruan, Qichao; Moradian-Oldak, Janet
2015-01-01
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recen...
Vandana Rathva
2012-01-01
Enamel pearls are one of a number of different enamel structures that can be found on the roots of deciduous and permanent teeth. They have a distinct predilection for the furcation areas of molar, particularly the maxillary third and second molars. However, they have been found less commonly on the apical portions of the root. This report describes an unusual case of enamel pearl on apical third of mandibular molar teeth. Enamel pearl was confirmed as predisposing factor for the cause of loc...
[Phenotype analysis and the molecular mechanism of enamel hypoplasia].
Lv, Ping; Gao, Xue-jun
2009-02-18
Enamel hypoplasia is a surface defect of the tooth crown caused by a disturbance of enamel matrix secretion. Enamel hypoplasia may be inherited, or result from illness, malnutrition, trauma, or high concentrations of fluorides or strontium in the drinking water or food. Different types of enamel hypoplasia have been distinguished, such as pit-type, plane-type, and linear enamel hypoplasia. Hypoplasia has been related to the intensity and duration of stress events, the number of affected ameloblasts, and their position along the forming tooth crown. Amelogenesis imperfecta (AI) is a heterogeneous group of inherited defects in dental enamel formation, most teeth are affected in both the primary and permanent dentition. The malformed enamel can be unusually thin, soft, rough and stained. The strict definition of AI includes only those cases where enamel defects occur in the absence of other symptoms. Currently, there are seven candidate genes for AI: amelogenin, enamelin, ameloblastin, tuftelin, distal-less homeobox 3, enamelysin, and kallikrein 4. Since the enamel is formed according to a strict chronological sequence, and once formed, undergoes no repair or regeneration. Then the analysis the phenotype of enamel hypoplasia can provide insights of the severity of inherited or environmental stress and the molecular mechanism during the period of enamel formation.
Energy of knots and conformal geometry
O'Hara, Jun
2003-01-01
Energy of knots is a theory that was introduced to create a "canonical configuration" of a knot - a beautiful knot which represents its knot type. This book introduces several kinds of energies, and studies the problem of whether or not there is a "canonical configuration" of a knot in each knot type. It also considers this problems in the context of conformal geometry. The energies presented in the book are defined geometrically. They measure the complexity of embeddings and have applications to physical knotting and unknotting through numerical experiments. Contents: In Search of the "Optima
Finkelstein, Robert J.
It is shown that the four quantum trefoil solitons that are described by the irreducible representations { D}3/2mm' of the quantum algebra SLq(2) [and that may be identified with the four families of elementary fermions (e, μ, τ νeνμντd, s, b; u, c, t)] may be built out of three preons, chosen from two charged preons with charges (1/3, -1/3) and two neutral preons. These preons are fermions and are described by the { D}1/2mm' representation of SLq(2). There are also four bosonic preons described by the { D}1mm^' and { D}000 representations of SLq(2). The knotted standard theory may be replicated at the preon level and the conjectured particles are in principle indirectly observable.
Knot invariants from Virasoro related representation and pretzel knots
Galakhov, D; Mironov, A; Morozov, A
2015-01-01
We remind the method to calculate colored Jones polynomials for the plat representations of knot diagrams from the knowledge of modular transformation (monodromies) of Virasoro conformal blocks with insertions of degenerate fields. As an illustration we use a rich family of pretzel knots, lying on a surface of arbitrary genus g, which was recently analyzed by the evolution method. Further generalizations can be to generic Virasoro modular transformations, provided by integral kernels, which can lead to the Hikami invariants.
Cosmetic crossings of genus one knots
Balm, Cheryl
2011-01-01
We show that for genus one knots the Alexander polynomial and the homology of the double cover branching over the knot provide obstructions to cosmetic crossings. As an application we prove the nugatory crossing conjecture for the negatively twisted, positive Whitehead doubles of all knots. We also verify the conjecture for several families of pretzel knots and all genus one knots with up to 10 crossings.
Amelogenin and Enamel Biomimetics
Ruan, Qichao; Moradian-Oldak, Janet
2015-01-01
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel. PMID:26251723
Handbook of knotting and splicing
Hasluck, Paul N
2005-01-01
Clearly written and amply illustrated with 208 figures, this classic guide ranges from simple and useful knots to complex varieties. Additional topics include rope splicing, working cordage, hammock making, more.
Effects of knots on protein folding properties.
Miguel A Soler
Full Text Available This work explores the impact of knots, knot depth and motif of the threading terminus in protein folding properties (kinetics, thermodynamics and mechanism via extensive Monte Carlo simulations of lattice models. A knotted backbone has no effect on protein thermodynamic stability but it may affect key aspects of folding kinetics. In this regard, we found clear evidence for a functional advantage of knots: knots enhance kinetic stability because a knotted protein unfolds at a distinctively slower rate than its unknotted counterpart. However, an increase in knot deepness does not necessarily lead to more effective changes in folding properties. In this regard, a terminus with a non-trivial conformation (e.g. hairpin can have a more dramatic effect in enhancing kinetic stability than knot depth. Nevertheless, our results suggest that the probability of the denatured ensemble to keep knotted is higher for proteins with deeper knots, indicating that knot depth plays a role in determining the topology of the denatured state. Refolding simulations starting from denatured knotted conformations show that not every knot is able to nucleate folding and further indicate that the formation of the knotting loop is a key event in the folding of knotted trefoils. They also show that there are specific native contacts within the knotted core that are crucial to keep a native knotting loop in denatured conformations which otherwise have no detectable structure. The study of the knotting mechanism reveals that the threading of the knotting loop generally occurs towards late folding in conformations that exhibit a significant degree of structural consolidation.
Weaving knotted vector fields with tunable helicity
Kedia, Hridesh; Dennis, Mark R; Irvine, William T M
2016-01-01
We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot and its generalizations. As finite-energy physical fields they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.
Universal Racah matrices and adjoint knot polynomials: Arborescent knots
Mironov, A.; Morozov, A.
2016-04-01
By now it is well established that the quantum dimensions of descendants of the adjoint representation can be described in a universal form, independent of a particular family of simple Lie algebras. The Rosso-Jones formula then implies a universal description of the adjoint knot polynomials for torus knots, which in particular unifies the HOMFLY (SUN) and Kauffman (SON) polynomials. For E8 the adjoint representation is also fundamental. We suggest to extend the universality from the dimensions to the Racah matrices and this immediately produces a unified description of the adjoint knot polynomials for all arborescent (double-fat) knots, including twist, 2-bridge and pretzel. Technically we develop together the universality and the "eigenvalue conjecture", which expresses the Racah and mixing matrices through the eigenvalues of the quantum R-matrix, and for dealing with the adjoint polynomials one has to extend it to the previously unknown 6 × 6 case. The adjoint polynomials do not distinguish between mutants and therefore are not very efficient in knot theory, however, universal polynomials in higher representations can probably be better in this respect.
Vandana Rathva
2012-04-01
Full Text Available Enamel pearls are one of a number of different enamel structures that can be found on the roots of deciduous and permanent teeth. They have a distinct predilection for the furcation areas of molar, particularly the maxillary third and second molars. However, they have been found less commonly on the apical portions of the root. This report describes an unusual case of enamel pearl on apical third of mandibular molar teeth. Enamel pearl was confirmed as predisposing factor for the cause of localized periodontitis; it is very important to recognize their radiographic aspect to ensure proper treatment of involved teeth.
Analysis of enamel development using murine model systems: approaches and limitations
Pugach, Megan K.; Gibson, Carolyn W.
2014-01-01
A primary goal of enamel research is to understand and potentially treat or prevent enamel defects related to amelogenesis imperfecta (AI). Rodents are ideal models to assist our understanding of how enamel is formed because they are easily genetically modified, and their continuously erupting incisors display all stages of enamel development and mineralization. While numerous methods have been developed to generate and analyze genetically modified rodent enamel, it is crucial to understand the limitations and challenges associated with these methods in order to draw appropriate conclusions that can be applied translationally, to AI patient care. We have highlighted methods involved in generating and analyzing rodent enamel and potential approaches to overcoming limitations of these methods: (1) generating transgenic, knockout, and knockin mouse models, and (2) analyzing rodent enamel mineral density and functional properties (structure and mechanics) of mature enamel. There is a need for a standardized workflow to analyze enamel phenotypes in rodent models so that investigators can compare data from different studies. These methods include analyses of gene and protein expression, developing enamel histology, enamel pigment, degree of mineralization, enamel structure, and mechanical properties. Standardization of these methods with regard to stage of enamel development and sample preparation is crucial, and ideally investigators can use correlative and complementary techniques with the understanding that developing mouse enamel is dynamic and complex. PMID:25278900
Analysis of enamel development using murine model systems: approaches and limitations.
Megan K Pugach
2014-09-01
Full Text Available A primary goal of enamel research is to understand and potentially treat or prevent enamel defects related to amelogenesis imperfecta (AI. Rodents are ideal models to assist our understanding of how enamel is formed because they are easily genetically modified, and their continuously erupting incisors display all stages of enamel development and mineralization. While numerous methods have been developed to generate and analyze genetically modified rodent enamel, it is crucial to understand the limitations and challenges associated with these methods in order to draw appropriate conclusions that can be applied translationally, to AI patient care. We have highlighted methods involved in generating and analyzing rodent enamel and potential approaches to overcoming limitations of these methods: 1 generating transgenic, knockout and knockin mouse models, and 2 analyzing rodent enamel mineral density and functional properties (structure, mechanics of mature enamel. There is a need for a standardized workflow to analyze enamel phenotypes in rodent models so that investigators can compare data from different studies. These methods include analyses of gene and protein expression, developing enamel histology, enamel pigment, degree of mineralization, enamel structure and mechanical properties. Standardization of these methods with regard to stage of enamel development and sample preparation is crucial, and ideally investigators can use correlative and complementary techniques with the understanding that developing mouse enamel is dynamic and complex.
On ambiguity in knot polynomials for virtual knots
Morozov, A; Popolitov, A
2015-01-01
We claim that HOMFLY polynomials for virtual knots, defined with the help of the matrix-model recursion relations, contain more parameters, than just the usual $q$ and $A = q^N$. These parameters preserve topological invariance and do not show up in the case of ordinary (non-virtual) knots and links. They are most conveniently observed in the hypercube formalism: then they substitute $q$-dimensions of certain fat graphs, which are not constrained by recursion and can be chosen arbitrarily. The number of these new topological invariants seems to grow fast with the number of non-virtual crossings: 0, 1, 1, 5, 15, 91, 784, 9160, ... This number can be decreased by imposing the factorization requirement for composites, in addition to topological invariance -- still freedom remains. None of these new parameters, however, appear in HOMFLY for Kishino unknot, which thus remains unseparated from the ordinary unknots even by this enriched set of knot invariants.
On ambiguity in knot polynomials for virtual knots
Morozov, A.; Morozov, And.; Popolitov, A.
2016-06-01
We claim that HOMFLY polynomials for virtual knots, defined with the help of the matrix-model recursion relations, contain more parameters, than just the usual q and A =qN. These parameters preserve topological invariance and do not show up in the case of ordinary (non-virtual) knots and links. They are most conveniently observed in the hypercube formalism: then they substitute q-dimensions of certain fat graphs, which are not constrained by recursion and can be chosen arbitrarily. The number of these new topological invariants seems to grow fast with the number of non-virtual crossings: 0, 1, 1, 5, 15, 91, 784, 9160, ... This number can be decreased by imposing the factorization requirement for composites, in addition to topological invariance - still freedom remains. None of these new parameters, however, appears in HOMFLY for Kishino unknot, which thus remains unseparated from the ordinary unknots even by this enriched set of knot invariants.
Planar and spherical stick indices of knots
Adams, Colin; Hawkins, Katherine; Sia, Charmaine; Silversmith, Rob; Tshishiku, Bena; 10.1142/S0218216511008954
2011-01-01
The stick index of a knot is the least number of line segments required to build the knot in space. We define two analogous 2-dimensional invariants, the planar stick index, which is the least number of line segments in the plane to build a projection, and the spherical stick index, which is the least number of great circle arcs to build a projection on the sphere. We find bounds on these quantities in terms of other knot invariants, and give planar stick and spherical stick constructions for torus knots and for compositions of trefoils. In particular, unlike most knot invariants,we show that the spherical stick index distinguishes between the granny and square knots, and that composing a nontrivial knot with a second nontrivial knot need not increase its spherical stick index.
Widmar, Marge
1985-01-01
A secondary teacher describes how she has her students use liquid white enamel. With the enameling process, students can create lasting, exciting artwork. They can exercise an understanding of design and color while learning the value of careful, sustained craft skills. (RM)
Widmar, Marge
1985-01-01
A secondary teacher describes how she has her students use liquid white enamel. With the enameling process, students can create lasting, exciting artwork. They can exercise an understanding of design and color while learning the value of careful, sustained craft skills. (RM)
Triad ''Metal - Enamel - Glass''
Mukhina, T.; Petrova, S.; Toporova, V.; Fedyaeva, T.
2014-10-01
This article shows how to change the color of metal and glass. Both these materials are self-sufficient, but sometimes used together. For example, enameling. In this case, the adhesion between metal substrate and stekloobraznae enamel layer, which was conducted on a stretching and a bend, was tested.
Żądzińska, Elżbieta; Lorkiewicz, Wiesław; Kurek, Marta; Borowska-Strugińska, Beata
2015-07-01
Physiological disruptions resulting from an impoverished environment during the first years of life are of key importance for the health and biological status of individuals and populations. Studies of growth processes in archaeological populations point to the fact that the main causes of childhood mortality in the past are to be sought among extrinsic factors. Based on this assumption, one would expect random mortality of children, with the deceased individuals representing the entire subadult population. The purpose of this study is to explore whether differences in early childhood survival are reflected in differences in deciduous tooth enamel, which can provide an insight into the development of an individual during prenatal and perinatal ontogeny. Deciduous incisors were taken from 83 individuals aged 2.0-6.5 years from a medieval inhumation cemetery dated AD 1300-1600. Prenatal and postnatal enamel formation time, neonatal line width, and the number of accentuated lines were measured using an optical microscope. The significantly wider neonatal line and the higher frequency of accentuated lines in the enamel of the incisors of children who died at the age of 2-3 years suggest the occurrence of stronger or more frequent stress events in this group. These results indicate that in skeletal populations mortality was not exclusively determined by random external factors. Individuals predisposed by an unfavorable course of prenatal and perinatal growth were more likely to die in early childhood.
Universal Racah matrices and adjoint knot polynomials. I. Arborescent knots
Mironov, A
2015-01-01
By now it is well established that the quantum dimensions of descendants of the adjoint representation can be described in a universal form, independent of a particular family of simple Lie algebras. The Rosso-Jones formula then implies a universal description of the adjoint knot polynomials for torus knots, which in particular unifies the HOMFLY (SU_N) and Kauffman (SO_N) polynomials. For E_8 the adjoint representation is also fundamental. We suggest to extend the universality from the dimensions to the Racah matrices and this immediately produces a unified description of the adjoint knot polynomials for all arborescent (double-fat) knots, including twist, 2-bridge and pretzel. Technically we develop together the universality and the "eigenvalue conjecture", which expresses the Racah and mixing matrices through the eigenvalues of the quantum R-matrix, and for dealing with the adjoint polynomials one has to extend it to the previously unknown 6x6 case. The adjoint polynomials do not distinguish between mutant...
Introduction to Virtual Knot Theory
Kauffman, Louis H
2011-01-01
This paper is an introduction to virtual knot theory and an exposition of new ideas and constructions, including the parity bracket polynomial, the arrow polynomial, the parity arrow polynomial and categorifications of the arrow polynomial. The paper is relatively self-contained and it describes virtual knot theory both combinatorially and in terms of the knot theory in thickened surfaces. The arrow polynomial (of Dye and Kauffman) is a natural generalization of the Jones polynomial, obtained by using the oriented structure of diagrams in the state sum. The paper discusses uses of parity pioneered by Vassily Manturov and uses his parity bracket polynomial to give a counterexample to a conjecture of Fenn, Kauffman and Manturov. The paper gives an exposition of the categorification of the arrow polynomial due to Dye, Kauffman and Manturov and it gives one example (from many found by Aaron Kaestner) of a pair of virtual knots that are not distinguished by Khovanov homology (mod 2), or by the arrow polynomial, bu...
Duality properties of indicatrices of knots
Adams, Colin; Hawkins, Katherine; Sia, Charmaine; Silversmith, Robert; Tshishiku, Bena
2012-01-01
The bridge index and superbridge index of a knot are important invariants in knot theory. We define the bridge map of a knot conformation, which is closely related to these two invariants, and interpret it in terms of the tangent indicatrix of the knot conformation. Using the concepts of dual and derivative curves of spherical curves as introduced by Arnold, we show that the graph of the bridge map is the union of the binormal indicatrix, its antipodal curve, and some number of great circles. Similarly, we define the inflection map of a knot conformation, interpret it in terms of the binormal indicatrix, and express its graph in terms of the tangent indicatrix. This duality relationship is also studied for another dual pair of curves, the normal and Darboux indicatrices of a knot conformation. The analogous concepts are defined and results are derived for stick knots.
Protein- mediated enamel mineralization
Moradian-Oldak, Janet
2012-01-01
Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth. PMID:22652761
Enamel hypoplasia: challenges of esthetic restorative treatment.
Ruschel, Vanessa Carla; Araújo, Élito; Bernardon, Jussara Karina; Lopes, Guilherme Carpena
2016-01-01
Enamel defects, such as white or yellow-brown spots, usually cause problems that are more esthetic than functional. Enamel hypoplasia may be the result of hereditary, systemic, or local factors. Dental trauma is a local etiologic factor. It is relatively common in the primary dentition and can cause defects on the surface of permanent successors. Treatment for such defects can differ, depending on the depth of the spots. For deeper white-spot lesions, a composite resin restoration may be necessary. This is an excellent mode of treatment, due to both its low cost and its conservation of healthy tooth structure. The objective of this case report is to describe composite resin restoration of a maxillary central incisor affected by enamel hypoplasia.
Adams operators and knot decorations
Aiston, A K
1997-01-01
We use an explicit isomorphism from the representation ring of the quantum group U_q(sl(N)) to the Homfly skein of the annulus, to determine an element of the skein which is the image of the mth Adams operator, \\psi_m, on the fundamental representation, c_1. This element is a linear combination of m very simple m-string braids. Using this skein element, we show that the Vassiliev invariant of degree n in the power series expansion of the U_q(sl(N)) quantum invariant of a knot coloured by \\psi_m(c_1) is the canonical Vassiliev invariant with weight system W_n\\psi_m^{(n)} where W_n is the weight system for the Vassiliev invariant of degree n in the expansion of the quantum invariant of the knot coloured by c_1 and \\psi_m^{(n)} is the Adams operator on n-chord diagrams defined by Bar-Natan.
Vortex knots in tangled quantum eigenfunctions
Taylor, Alexander J
2016-01-01
Tangles of string typically become knotted, from macroscopic twine down to long-chain macromolecules such as DNA. Here we demonstrate that knotting also occurs in quantum wavefunctions, where the tangled filaments are vortices (nodal lines/phase singularities). The probability that a vortex loop is knotted is found to increase with its length, and a wide gamut of knots from standard tabulations occur. The results follow from computer simulations of random superpositions of degenerate eigenstates of three simple quantum systems: a cube with periodic boundaries, the isotropic 3-dimensional harmonic oscillator and the 3-sphere. In the latter two cases, vortex knots occur frequently, even in random eigenfunctions at relatively low energy, and are constrained by the spatial symmetries of the modes. The results suggest that knotted vortex structures are generic in complex 3-dimensional wave systems, establishing a topological commonality between wave chaos, polymers and turbulent Bose-Einstein condensates.
Endoscopic Release of Master Knot of Henry.
Lui, Tun Hing
2015-12-01
A post-traumatic partial tear of the flexor hallucis longus tendon at the master knot of Henry and the resultant fibrosis of the knot can result in pain at the medial foot arch or posteromedial ankle pain with trigger hallux. Open debridement of the master knot of Henry is indicated if the symptoms do not improve with nonoperative treatment. The open procedure requires extensive soft-tissue dissection because the master knot of Henry is a deep structure. Endoscopic release of the master knot of Henry is an alternative to the open procedure and has the advantage of less surgical trauma and potential for less chance of recurrence of fibrosis of the master knot of Henry.
Knotted solitons in nonlinear magnetic metamaterials.
Rosanov, Nikolay N; Vysotina, Nina V; Shatsev, Anatoly N; Desyatnikov, Anton S; Kivshar, Yuri S
2012-03-30
We demonstrate that nonlinear magnetic metamaterials comprised of a lattice of weakly coupled split-ring resonators driven by an external electromagnetic field may support entirely new classes of spatially localized modes--knotted solitons, which are stable self-localized dissipative structures in the form of closed knotted chains. We demonstrate different topological types of stable knots for the subcritical coupling between resonators and instability-induced breaking of the chains for the supercritical coupling.
Knowledge of knots: shapes in action
Casati, Roberto
2013-01-01
Logic is to natural language what knot theory is to natural knots. Logic is concerned with some cognitive performances; in particular, some natural language inferences are captured by various types of calculi (propositional, predicate, modal, deontic, quantum, probabilistic, etc.), which in turn may generate inferences that are arguably beyond natural logic abilities, or non-well synchronized therewith (eg. ex falso quodlibet, material implication). Mathematical knot theory accounts for some ...
Coherent band pathways between knots and links
Buck, Dorothy
2014-01-01
We categorise coherent band (aka nullification) pathways between knots and 2-component links. Additionally, we characterise the minimal coherent band pathways (with intermediates) between any two knots or 2-component links with small crossing number. We demonstrate these band surgeries for knots and links with small crossing number. We apply these results to place lower bounds on the minimum number of recombinant events separating DNA configurations, restrict the recombination pathways and determine chirality and/or orientation of the resulting recombinant DNA molecules.
俞少玲; 李姮; 王文梅
2015-01-01
目的：研究局部应用奥敏清牙齿脱敏剂对可乐酸蚀脱矿乳牙釉质再矿化的作用。方法：收集临床因滞留拔除的健康乳磨牙30颗，将每颗牙沿颊舌向和近远中向纵切成4个牙块，随机进入A、B、C、D组（n＝30）。经碳酸饮料浸泡脱矿（10 min×10次／d×7 d）后，进行如下处理：A组（不处理）、B组（奥敏清牙齿脱敏剂处理）、C组（氟化物处理）、D组（奥敏清牙齿脱敏剂与氟化物联合处理），分别处理2 min×2次／d×7 d。用激光荧光龋探测仪（DIAGN－Odent）记录各时间点的荧光值，扫描电镜（SEM）观察各组釉质表面形态。结果：与A组相比，再矿化处理后B、C、D组荧光值显著降低（P＜0．01）。D组荧光值显著低于B、C组（P＜0．05），而B、C两组无统计学差异（P＞0．05）。SEM下经奥敏清牙齿脱敏剂或氟化物处理后表面均有一定沉积物。结论：奥敏清牙齿脱敏剂具有促乳牙脱矿釉质再矿化的作用，与氟化物联合应用具有加强协同作用。%Objective:To study the effect of topical Minqing Ao dental desensitizer application on the remineraliza-tion of primary teeth enamel eroded by Cola. Method:30 retained human primary molars were collected at clinic.Each tooth was cut bucco-lingually and mesial-distally into four sections. These sections assigned randomly to one of four groups (n=30). The enamel slabs were first immersed into a carbonated acidic drink for demineralization treatment for seven days(10 min×10 times/d),then they were treated as follows for seven days(2 min×2 times/d):Group A(unexposed to any prod-uct)、Group B(Minqing Ao dental desensitizer)、Group C(fluoride)、Group D(Minqing Ao dental desensitizer +fluoride). A laser fluorescence system(DIAGNOdent)was used to make a quantitative record,The morphological changes of surface were observed by scanning electron microscope (SEM). Result:Compared with group A after
The mathematics and physics of knots
Kauffman, Louis H [Department of Mathematics, Statistics and Computer Science, University of Illinois at Chicago, 851 South Morgan Street, Chicago, IL 60607-7045 (United States)
2005-12-01
This paper is an introduction to relationships between knot theory and theoretical physics. We give an exposition of the theory of polynomial invariants of knots and links, the Witten functional integral formulation of knot and link invariants, and the beginnings of topological quantum field theory, and show how the theory of knots is related to a number of key issues in mathematical physics, including loop quantum gravity and quantum information theory. Along with the references cited in the text below, we also recommend the following as sources of background information.
Enamel Hypoplasia of Deciduous Canine
加納, 隆; 平出, 百合子; 舟津, 聡; 峯村, 隆一; 恩田, 千爾; 正木, 岳馬
1993-01-01
From observation of frequency and measurement of the lengths and widths of enamel hypoplasia on the maxillary and mandibular deciduous canines, extracted from 50 Indians' skulls, the following results were obtained. 1) Enamel hypoplasia occurred in 15% of the maxillary deciduous canines and 44% of the mandibular deciduous canines. 2) Symmetrical cases of enamel hypoplasia occurred in 8.0% of the maxillary deciduous canins and in 34% of the mandibular deciduous canines. The enamel hypoplasia o...
Nanolayering of phosphoric acid ester monomer on enamel and dentin.
Yoshihara, Kumiko; Yoshida, Yasuhiro; Hayakawa, Satoshi; Nagaoka, Noriyuki; Irie, Masao; Ogawa, Tatsuyuki; Van Landuyt, Kirsten L; Osaka, Akiyoshi; Suzuki, Kazuomi; Minagi, Shogo; Van Meerbeek, Bart
2011-08-01
Following the "adhesion-decalcification" concept, specific functional monomers possess the capacity to primary chemically interact with hydroxyapatite (HAp). Such ionic bonding with synthetic HAp has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), manifest as self-assembled "nanolayering". In continuation of that basic research this study aimed to explore whether nanolayering also occurs on enamel and dentin when a 10-MDP primer is applied following a common clinical application protocol. Therefore, the interaction of an experimental 10-MDP primer and a control, commercially available, 10-MDP-based primer (Clearfil SE Bond primer (C-SE), Kuraray) with enamel and dentin was characterized by X-ray diffraction (XRD), complemented with transmission electron microscopy interfacial ultrastructural data upon their reaction with enamel and dentin. In addition, XRD was used to study the effect of the concentration of 10-MDP on nanolayering on dentin. Finally, the stability of the nanolayers was determined by measuring the bond strength to enamel and dentin when a photoinitiator was added to the experimental primer or when interfacial polymerization depended solely on the photoinitiator supplied with the subsequently applied adhesive resin. XRD confirmed nanolayering on enamel and dentin, which was significantly greater on dentin than on enamel, and also when the surface was actively rubbed with the primer. Nanolayering was also proportional to the concentration of 10-MDP in the primer. Finally, the experimental primer needed the photoinitiator to obtain a tensile bond strength to dentin comparable with that of the control C-SE primer (which also contains a photoinitiator), but not when bonded to enamel. It is concluded that self-assembled nanolayering occurs on enamel and dentin, even when following a clinically used application protocol. The lower bonding effectiveness of mild self-etch adhesives to enamel should be ascribed in part to a lower
Differential and symplectic topology of knots and curves
Tabachnikov, S
1999-01-01
This book presents a collection of papers on two related topics: topology of knots and knot-like objects (such as curves on surfaces) and topology of Legendrian knots and links in 3-dimensional contact manifolds. Featured is the work of international experts in knot theory (""quantum"" knot invariants, knot invariants of finite type), in symplectic and contact topology, and in singularity theory. The interplay of diverse methods from these fields makes this volume unique in the study of Legendrian knots and knot-like objects such as wave fronts. A particularly enticing feature of the volume is
Cosmetic surgeries on knots in $S^3$
Ni, Yi
2010-01-01
Two Dehn surgeries on a knot are called {\\it purely cosmetic}, if they yield manifolds that are homeomorphic as oriented manifolds. Using Heegaard Floer homology, we give necessary conditions for the existence of purely cosmetic surgeries on knots in $S^3$. Among other things, we show that the two surgery slopes must be the opposite of each other.
Diagnosis of true umbilical cord knot.
Guzikowski, Wojciech; Kowalczyk, Dariusz; Więcek, Jacek
2014-02-24
Many abnormalities are observed in the morphology and pathology of the umbilical cord. The aim of the study was to assess the role of 3D sonography in pathology of true umbilical cord knots. In our materials we observed 10 cases of true umbilical cord knots in a population of 2,864 deliveries. The 2-dimensional transverse scan of the umbilical cord was shown in 3- and 4-dimensional volume scan in order to get a precise image. Four knots were diagnosed prenatally, 3 knots were not diagnosed before the delivery and in the 3 remaining cases ultrasound examinations were not undertaken because the patients were in the course of delivery. In the pregnant subjects with diagnosed true umbilical cord knot once a week the Doppler blood flow indices were examined in the umbilical cord sections before and after the knot. In the three shown cases there were no signs of constriction or tightening of the knot. Four newborns were delivered spontaneously and five by caesarean section. In none of the cases was a pathological FHR trace an indication for emergency delivery. Four-dimensional and Color Doppler examination is very important to diagnose a true umbilical cord. To make a precise diagnosis a longer observation of the abnormality is necessary and its repeated confirmation by color Doppler and power Doppler. This diagnosis requires strict monitoring of fetal wellbeing during pregnancy and the delivery. Perfection of true umbilical cord knot diagnoses may reduce sudden and unforeseen fetal distress.
Knot strength of nylon-band cerclage.
Kirby, B M; Wilson, J W
1989-12-01
Nylon bands of five sizes were tested to failure using a splint circular jaw mounted on a tensile testing machine. Four treatment groups of each of the five sizes were tested: as supplied by the manufacturer, ethylene oxide sterilized, autoclave sterilized, and saline-soaked. Comparisons were made between groups and to previously reported results of similar testing of stainless steel wire of three sizes. All the bands failed at the lock mechanism. Knot strength increased with increased size of nylon band. There was no difference between untreated and ethylene oxide sterilized bands, whereas bands subjected to autoclaving or saline soaking failed at less force. The knot strength of all the treatment groups in the three smaller sizes of bands was less than twist-knotted 0.8-mm wire cerclage; and when soaked in saline for 24 hours, the knot strength of the two largest size bands dropped to less than 1.2-mm twist-knotted wire.
Star-formation knots in IRAS galaxies
Hutchings, J B
1995-01-01
Images of IRAS galaxies with a range of IR properties are examined for bright knots, both within and outside the galaxy. These are found almost exclusively in galaxies with steep IR spectra, but over a wide range of IR luminosity, and usually without strong nuclear activity. In most cases, the knots are likely to be star-formation induced by tidal interactions, and are seen in the early stages of such interactions. Detailed photometry is presented of knots in six representative galaxies. The knots appear to have a wide range of colour and luminosity, but it is argued that many are heavily reddened. Knots formed outside the parent galaxy may be a new generation of what later become globular clusters, but they appear to have a wide range of luminosities.
Microstructure and mineral composition of dental enamel of permanent and deciduous teeth.
De Menezes Oliveira, Maria Angélica Hueb; Torres, Carolina Paes; Gomes-Silva, Jaciara Miranda; Chinelatti, Michelle Alexandra; De Menezes, Fernando Carlos Hueb; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina
2010-05-01
This study evaluated and compared in vitro the microstructure and mineral composition of permanent and deciduous teeth's dental enamel. Sound third molars (n = 12) and second primary molars (n = 12) were selected and randomly assigned to the following groups, according to the analysis method performed (n = 4): Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Energy dispersive X-ray spectrometer (EDS). Qualitative and quantitative comparisons of the dental enamel were done. The microscopic findings were analyzed statistically by a nonparametric test (Kruskal-Wallis). The measurements of the prisms number and thickness were done in SEM photomicrographs. The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Chemical phases present in both types of teeth were observed by the XRD analysis. The mean thickness measurements observed in the deciduous teeth enamel was 1.14 mm and in the permanent teeth enamel was 2.58 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enamel-dentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The percentage of Ca and P was higher in the permanent teeth enamel. The primary enamel structure showed a lower level of Ca and P, thinner thickness and higher numerical density of rods. (c) 2009 Wiley-Liss, Inc.
A pseudo-haptic knot diagram interface
Zhang, Hui; Weng, Jianguang; Hanson, Andrew J.
2011-01-01
To make progress in understanding knot theory, we will need to interact with the projected representations of mathematical knots which are of course continuous in 3D but significantly interrupted in the projective images. One way to achieve such a goal would be to design an interactive system that allows us to sketch 2D knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress to be made in this direction. Pseudo-haptics that simulates haptic effects using pure visual feedback can be used to develop such an interactive system. This paper outlines one such pseudo-haptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a "physically" reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudo-haptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of whom the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudo-haptic 4D visualization system that simulates the continuous navigation on 4D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2D knot diagrams of 3D knots and 3D projective images of 4D mathematical objects.
Yeom, Bongjun; Sain, Trisha; Lacevic, Naida; Bukharina, Daria; Cha, Sang-Ho; Waas, Anthony M.; Arruda, Ellen M.; Kotov, Nicholas A.
2017-03-01
Tooth enamel comprises parallel microscale and nanoscale ceramic columns or prisms interlaced with a soft protein matrix. This structural motif is unusually consistent across all species from all geological eras. Such invariability—especially when juxtaposed with the diversity of other tissues—suggests the existence of a functional basis. Here we performed ex vivo replication of enamel-inspired columnar nanocomposites by sequential growth of zinc oxide nanowire carpets followed by layer-by-layer deposition of a polymeric matrix around these. We show that the mechanical properties of these nanocomposites, including hardness, are comparable to those of enamel despite the nanocomposites having a smaller hard-phase content. Our abiotic enamels have viscoelastic figures of merit (VFOM) and weight-adjusted VFOM that are similar to, or higher than, those of natural tooth enamels—we achieve values that exceed the traditional materials limits of 0.6 and 0.8, respectively. VFOM values describe resistance to vibrational damage, and our columnar composites demonstrate that light-weight materials of unusually high resistance to structural damage from shocks, environmental vibrations and oscillatory stress can be made using biomimetic design. The previously inaccessible combinations of high stiffness, damping and light weight that we achieve in these layer-by-layer composites are attributed to efficient energy dissipation in the interfacial portion of the organic phase. The in vivo contribution of this interfacial portion to macroscale deformations along the tooth’s normal is maximized when the architecture is columnar, suggesting an evolutionary advantage of the columnar motif in the enamel of living species. We expect our findings to apply to all columnar composites and to lead to the development of high-performance load-bearing materials.
Enamel formation and amelogenesis imperfecta.
Hu, Jan C-C; Chun, Yong-Hee P; Al Hazzazzi, Turki; Simmer, James P
2007-01-01
Dental enamel is the epithelial-derived hard tissue covering the crowns of teeth. It is the most highly mineralized and hardest tissue in the body. Dental enamel is acellular and has no physiological means of repair outside of the protective and remineralization potential provided by saliva. Enamel is comprised of highly organized hydroxyapatite crystals that form in a defined extracellular space, the contents of which are supplied and regulated by ameloblasts. The entire process is under genetic instruction. The genetic control of amelogenesis is poorly understood, but requires the activities of multiple components that are uniquely important for dental enamel formation. Amelogenesis imperfecta (AI) is a collective designation for the variety of inherited conditions displaying isolated enamel malformations, but the designation is also used to indicate the presence of an enamel phenotype in syndromes. Recently, genetic studies have demonstrated the importance of genes encoding enamel matrix proteins in the etiology of isolated AI. Here we review the essential elements of dental enamel formation and the results of genetic analyses that have identified disease-causing mutations in genes encoding enamel matrix proteins. In addition, we provide a fresh perspective on the roles matrix proteins play in catalyzing the biomineralization of dental enamel.
Open knot-tying skills: residents skills assessed
van Empel, P.J.; Verdam, M.G.E.; Huirne, J.A.; Bonjer, H.J.; Meijerink, W.J.; Scheele, F.
2013-01-01
Aim: Open knot-tying and suturing skills are fundamental surgical skills, founding many alternative knot-tying techniques. It is therefore mandatory for residents to possess adequate basic open knot-tying skills. The aim of this study was to compare an objective assessment of open knot-tying skills
Phase behaviour of polyethylene knotted ring chains
Wen Xiao-Hui; Zhang Lin-Xi; Xia A-Gen; Chen Hong-Ping
2011-01-01
The phase behaviour of polyethylene knotted ring chains is investigated by using molecular dynamics simulations.In this paper, we focus on the collapse of the polyethylene knotted ring chain, and also present the results of linear and ring chains for comparison. At high temperatures, a fully extensive knot structure is observed. The mean-square radius of gyration per bond〈S2〉/(Nb2)and the shape factor(δ*)depend on not only the chain length but also the knot type.With temperature decreasing, chain collapse is observed, and the collapse temperature decreases with the chain length increasing. The actual collapse transition can be determined by the specific heat capacity Cv, and the knotted ring chain undergoes gas-liquid-solid-like transition directly. The phase transition of a knotted ring chain is only one-stage collapse, which is different from the polyethylene linear and ring chains. This investigation can provide some insights into the statistical properties of knotted polymer chains.
On the concordance orders of knots
Collins, Julia
2012-01-01
This thesis develops some general calculational techniques for finding the orders of knots in the topological concordance group C. The techniques currently available in the literature are either too theoretical, applying to only a small number of knots, or are designed to only deal with a specific knot. The thesis builds on the results of Herald, Kirk and Livingston [HKL10] and Tamulis [Tam02] to give a series of criteria, using twisted Alexander polynomials, for determining whether a knot is of infinite order in C. There are two immediate applications of these theorems. The first is to give the structure of the subgroups of the concordance group C and the algebraic concordance group G generated by the prime knots of 9 or fewer crossings. This should be of practical value to the knot-theoretic community, but more importantly it provides interesting examples of phenomena both in the algebraic and geometric concordance groups. The second application is to find the concordance orders of all prime knots with up t...
Dental Enamel Development: Proteinases and Their Enamel Matrix Substrates
Bartlett, John D.
2013-01-01
This review focuses on recent discoveries and delves in detail about what is known about each of the proteins (amelogenin, ameloblastin, and enamelin) and proteinases (matrix metalloproteinase-20 and kallikrein-related peptidase-4) that are secreted into the enamel matrix. After an overview of enamel development, this review focuses on these enamel proteins by describing their nomenclature, tissue expression, functions, proteinase activation, and proteinase substrate specificity. These protei...
Torus knots and the rational DAHA
Gorsky, Eugene; Rasmussen, Jacob; Shende, Vivek
2012-01-01
We conjecturally extract the triply graded Khovanov-Rozansky homology of the (m, n) torus knot from the unique finite dimensional simple representation of the rational DAHA of type A, rank n - 1, and central character m/n. The conjectural differentials of Gukov, Dunfield and the third author receive an explicit algebraic expression in this picture, yielding a prescription for the doubly graded Khovanov-Rozansky homologies. We match our conjecture to previous conjectures of the first author relating knot homology to q, t-Catalan numbers, and of the last three authors relating knot homology to Hilbert schemes on singular curves.
Urethral catheter knotting: an avoidable complication
Ismail Burud
2013-03-01
Full Text Available Urethral catheterisation is a common andsafe procedure performed routinely. The small sizeof the urethra in a child necessitates the use of aninfant feeding tube (Size 5 to 8 F for catheterisation.Knotting within the bladder is a rare complication withsignificant morbidity often necessitating surgical orendoscopic removal. Insertion of an excessive lengthof tube contributes to coiling and knotting. We reportan instance of knotting of an infant feeding tube inthe proximal penile urethra of a 4 year-old male childrequiring urethrotomy to remove it. Awareness of therisk and proper technique can reduce this complication.
Knot Invariants from Classical Field Theories
Leal, L C
1999-01-01
We consider the Non-Abelian Chern-Simons term coupled to external particles, in a gauge and diffeomorphism invariant form. The classical equations of motion are perturbativelly studied, and the on-shell action is shown to produce knot-invariants associated with the sources. The first contributions are explicitly calculated, and the corresponding knot-invariants are recognized. We conclude that the interplay between Knot Theory and Topological Field Theories is manifested not only at the quantum level, but in a classical context as well.
Grid homology for knots and links
Ozsváth, Peter S; Szabó, Zoltán
2015-01-01
Knot theory is a classical area of low-dimensional topology, directly connected with the theory of three-manifolds and smooth four-manifold topology. In recent years, the subject has undergone transformative changes thanks to its connections with a number of other mathematical disciplines, including gauge theory; representation theory and categorification; contact geometry; and the theory of pseudo-holomorphic curves. Starting from the combinatorial point of view on knots using their grid diagrams, this book serves as an introduction to knot theory, specifically as it relates to some of the ab
Proteome and Peptidome of Human Acquired Enamel Pellicle on Deciduous Teeth
Jason N. Zimmerman
2013-01-01
Full Text Available Understanding the composition and structure of the acquired enamel pellicle (AEP has been a major goal in oral biology. Our lab has conducted studies on the composition of AEP formed on permanent enamel. The exhaustive exploration has provided a comprehensive identification of more than 100 proteins from AEP formed on permanent enamel. The AEP formed on deciduous enamel has not been subjected to the same biochemical characterization scrutiny as that of permanent enamel, despite the fact that deciduous enamel is structurally different from permanent enamel. We hypothesized that the AEP proteome and peptidome formed on deciduous enamel may also be composed of unique proteins, some of which may not be common with AEP of permanent enamel explored previously. Pellicle material was collected from 10 children (aged 18–54 months and subjected to mass spectrometry analysis. A total of 76 pellicle proteins were identified from the deciduous pellicle proteome. In addition, 38 natural occurring AEP peptides were identified from 10 proteins, suggesting that primary AEP proteome/peptidome presents a unique proteome composition. This is the first study to provide a comprehensive investigation of in vivo AEP formed on deciduous enamel.
Studying uniform thickness II: Transversely nonsimple iterated torus knots
LaFountain, Douglas
2011-01-01
We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...... classification for a large class of knots. We also show that all iterated torus knots that fail the UTP support cabling knot types that are transversely non-simple....
A Partial Order in the Knot Table Ⅱ
Teruaki KITANO; Masaaki SUZUKI
2008-01-01
A partial order on the set of the prime knots can be defined by the existence of a surjective homomorphism between knot groups.In the previous paper,we determined the partial order in the knot table.In this paper,we prove that 31 and 41 are minimal elements.Further,we study which surjection a pair of a periodic knot and its quotient knot induces,and which surjection a degree one map can induce.
Zeros of the Jones Polynomial for Torus Knots and 2-bridge Knots
HAN You-fa; ZHANG Rong-wei; WANG Lin-lin; MA Xiao-sha
2014-01-01
We study zeros of the Jones polynomial and their distributions for torus knots and 2-bridge knots. We prove that e(2m+1)πi/2 and e(2m+1)πi/4(m is a positive integer) can not be the zeros of Jones polynomial for torus knots Tp,q by the knowledge of the trigonometric function. We elicit the normal form of Jones polynomials of the 2-bridge knot C (−2, 2, · · · , (−1)r 2) by the recursive form and discuss the distribution of their zeros.
Hipoplasia Enamel Pada Penderita Penyakit Eksantema
Dewi saputri
2008-01-01
Hipoplasia enamel merupakan gangguan pada masa pemhentukan matriks organik yang menyebabkan gangguan struktur pada enamel sehingga secara klinis terlihat pada suatu bagian dari gigi tidak terbentuk enamel dan kadang-kadang sama sekali tidak terbentuk enamel, serta diikuti dengan perubahan warna pada gigi. Dikenal berbagai faktor penyebab hipoplasia enamel, salah satunya adalah penyakit eksantema yaitu menyebabkan infeksi pada bayi dan anak-anak. Gambaran histopatologis hipoplasia enamel adala...
Kleckner, Dustin; Irvine, William T M
2013-01-01
The idea that the knottedness (hydrodynamic Helicity) of a fluid flow is conserved has a long history in fluid mechanics. The quintessential example of a knotted flow is a knotted vortex filament, however, owing to experimental difficulties, it has not been possible until recently to directly generate knotted vortices in real fluids. Using 3D printed hydrofoils and high-speed laser scanning tomography, we generate vortex knots and links and measure their subsequent evolution. In both cases, we find that the vortices deform and stretch until a series of vortex reconnections occurs, eventually resulting several disjoint vortex rings. This article accompanies a fluid dynamics video entered into the Gallery of Fluid Motion at the 66th Annual Meeting of the APS Division of Fluid Dynamics.
Cotranslational folding of deeply knotted proteins
Chwastyk, Mateusz
2015-01-01
Proper folding of deeply knotted proteins has a very low success rate even in structure-based models which favor formation of the native contacts but have no topological bias. By employing a structure-based model, we demonstrate that cotranslational folding on a model ribosome may enhance the odds to form trefoil knots for protein YibK without any need to introduce any non-native contacts. The ribosome is represented by a repulsive wall that keeps elongating the protein. On-ribosome folding proceeds through a a slipknot conformation. We elucidate the mechanics and energetics of its formation. We show that the knotting probability in on-ribosome folding is a function of temperature and that there is an optimal temperature for the process. Our model often leads to the establishment of the native contacts without formation of the knot.
A Fourth KLK4 Mutation Is Associated with Enamel Hypomineralisation and Structural Abnormalities
Smith, Claire E. L.; Kirkham, Jennifer; Day, Peter F.; Soldani, Francesca; McDerra, Esther J.; Poulter, James A.; Inglehearn, Christopher F.; Mighell, Alan J.; Brookes, Steven J.
2017-01-01
“Amelogenesis imperfecta” (AI) describes a group of genetic conditions that result in defects in tooth enamel formation. Mutations in many genes are known to cause AI, including the gene encoding the serine protease, kallikrein related peptidase 4 (KLK4), expressed during the maturation stage of amelogenesis. In this study we report the fourth KLK4 mutation to be identified in autosomal recessively-inherited hypomaturation type AI, c.632delT, p.(L211Rfs*37) (NM_004917.4, NP_004908.4). This homozygous variant was identified in five Pakistani AI families and is predicted to result in a transcript with a premature stop codon that escapes nonsense mediated decay. However, the protein may misfold, as three of six disulphide bonds would be disrupted, and may be degraded or non-functional as a result. Primary teeth were obtained from one affected individual. The enamel phenotype was characterized using high-resolution computerized X-ray tomography (CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and microhardness testing (MH). Enamel from the affected individual (referred to as KLK4 enamel) was hypomineralised in comparison with matched control enamel. Furthermore, KLK4 inner enamel was hypomineralised compared with KLK4 outer enamel. SEM showed a clear structural demarcation between KLK4 inner and outer enamel, although enamel structure was similar to control tissue overall. EDX showed that KLK4 inner enamel contained less calcium and phosphorus and more nitrogen than control inner enamel and KLK4 outer enamel. MH testing showed that KLK4 inner enamel was significantly softer than KLK4 outer enamel (p enamel was not significantly different to that of control outer enamel. Overall, these findings suggest that the KLK4 c.632delT mutation may be a common cause of autosomal recessive AI in the Pakistani population. The phenotype data obtained mirror findings in the Klk4−/− mouse and suggest that KLK4 is required for the hardening
A Fourth KLK4 Mutation Is Associated with Enamel Hypomineralisation and Structural Abnormalities
Claire E. L. Smith
2017-05-01
Full Text Available “Amelogenesis imperfecta” (AI describes a group of genetic conditions that result in defects in tooth enamel formation. Mutations in many genes are known to cause AI, including the gene encoding the serine protease, kallikrein related peptidase 4 (KLK4, expressed during the maturation stage of amelogenesis. In this study we report the fourth KLK4 mutation to be identified in autosomal recessively-inherited hypomaturation type AI, c.632delT, p.(L211Rfs*37 (NM_004917.4, NP_004908.4. This homozygous variant was identified in five Pakistani AI families and is predicted to result in a transcript with a premature stop codon that escapes nonsense mediated decay. However, the protein may misfold, as three of six disulphide bonds would be disrupted, and may be degraded or non-functional as a result. Primary teeth were obtained from one affected individual. The enamel phenotype was characterized using high-resolution computerized X-ray tomography (CT, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX, and microhardness testing (MH. Enamel from the affected individual (referred to as KLK4 enamel was hypomineralised in comparison with matched control enamel. Furthermore, KLK4 inner enamel was hypomineralised compared with KLK4 outer enamel. SEM showed a clear structural demarcation between KLK4 inner and outer enamel, although enamel structure was similar to control tissue overall. EDX showed that KLK4 inner enamel contained less calcium and phosphorus and more nitrogen than control inner enamel and KLK4 outer enamel. MH testing showed that KLK4 inner enamel was significantly softer than KLK4 outer enamel (p < 0.001. However, the hardness of control inner enamel was not significantly different to that of control outer enamel. Overall, these findings suggest that the KLK4 c.632delT mutation may be a common cause of autosomal recessive AI in the Pakistani population. The phenotype data obtained mirror findings in the Klk4
The crossing number of composite knots
Lackenby, Marc
2008-01-01
It is a very old conjecture that the crossing number of knots is additive under connected sum. In other words, if K#K' is the connected sum of knots K and K', then does the equality c(K#K') = c(K) + c(K') hold? We prove that c(K#K') is at most c(K) + c(K') and at least (c(K) + c(K'))/152.
On rectangular HOMFLY for twist knots
Kononov, Ya
2016-01-01
As a new step in the study of rectangularly-colored knot polynomials, we reformulate the prescription of arXiv:1606.06015 for twist knots in the double-column representations $R=[rr]$ in terms of skew Schur polynomials. These, however, are mysteriously shifted from the standard topological locus, what makes further generalization to arbitrary $R=[r^s]$ not quite straightforward.
Counting Links and Knots in Complete Graphs
Abrams, Loren
2010-01-01
We investigate the minimal number of links and knots in complete partite graphs. We provide exact values or bounds on the minimal number of links for all complete partite graphs with all but 4 vertices in one partition, or with 9 vertices in total. In particular, we find that the minimal number of links for $K_{4,4,1}$ is 74. We also provide exact values or bounds on the minimal number of knots for all complete partite graphs with 8 vertices.
Twisted Alexander polynomials of hyperbolic knots
Dunfield, Nathan M; Jackson, Nicholas
2011-01-01
We study a twisted Alexander polynomial naturally associated to a hyperbolic knot in an integer homology 3-sphere via a lift of the holonomy representation to SL(2, C). It is an unambiguous symmetric Laurent polynomial whose coefficients lie in the trace field of the knot. It contains information about genus, fibering, and chirality, and moreover is powerful enough to sometimes detect mutation. We calculated this invariant numerically for all 313,209 hyperbolic knots in S^3 with at most 15 crossings, and found that in all cases it gave a sharp bound on the genus of the knot and determined both fibering and chirality. We also study how such twisted Alexander polynomials vary as one moves around in an irreducible component X_0 of the SL(2, C)-character variety of the knot group. We show how to understand all of these polynomials at once in terms of a polynomial whose coefficients lie in the function field of X_0. We use this to help explain some of the patterns observed for knots in S^3, and explore a potential...
Self-assembly of knots and links
Orlandini, Enzo; Polles, Guido; Marenduzzo, Davide; Micheletti, Cristian
2017-03-01
Guiding the self-assembly of identical building blocks towards complex three-dimensional structures with a set of desired properties is a major goal in material science, chemistry and physics. A particularly challenging problem, especially explored in synthetic chemistry, is that of self-assembling closed structures with a target topology starting by simple geometrical templates. Here we overview and revisit recent advancements, based on stochastic simulations, where the geometry of rigid helical templates with functionalised sticky ends has been designed for self-assembling efficiently and reproducibly into a wide range of three-dimensional closed structures. Notably, these include non trivial topologies of links and knots, including the 819 knot that we had predicted to be highly encodable and that has only recently been obtained experimentally. By appropriately tuning the parameters that define the template shape, we show that, for fixed concentration of templates, the assembly process can be directed towards the formation of specific knotted and linked structures such as the trefoils, pentafoil knots, Hopf and Solomon links. More exotic and unexpected knots and links are also found. Our results should be relevant to the design of new protocols that can both increase and broaden the population of synthetise molecular knots and catenanes.
Torus Knots and the Topological Vertex
Jockers, Hans; Soroush, Masoud
2012-01-01
We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S^3. The key role is played by the SL(2,Z) transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Marino. Comparing to the recent proposal by Aganagic and Vafa for knots on S^3, we demonstrate that the disk amplitude of the A-brane associated to any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.
Ana Alicia Vallejos-Sánchez
2007-06-01
Full Text Available Objetivo: Explorar la relación entre la presencia de defectos del esmalte (DE, la experiencia de caries en la dentición temporal, y la exposición a diversas fuentes de fluoruros, con la presencia de caries en la dentición permanente de niños con dentición mixta. Material y métodos: Se realizó un estudio transversal en 713 sujetos de 6-9 años de edad de 4 escuelas de Campeche, México, mediante un cuestionario dirigido a las madres, y un examen clínico bucal a los niños. La variable dependiente fue la prevalencia de caries en la dentición permanente. Resultados: El promedio de dientes temporales cariados, extraídos y obturados (ceod y dientes permanentes cariados, perdidos y obturados (CPOD fue de 2,48 (2,82 (ceod > 0 = 58,9% y 0,40 (0,98 (CPOD > 0 = 18,2%, respectivamente. El índice SiC (índice de caries significativa, calculado en la dentición temporal fue de 5,85 para los niños de 6 años de edad. En el análisis de regresión logística multivariado permanecieron significativas, después de ajustar por variables de exposición a fluoruros, la mayor edad (odds ratio [OR] = 2,99, el ceod > 0 (OR = 5,46, la menor escolaridad de la madre (OR = 1,57 y una interacción entre sexo y defectos del esmalte. Conclusiones: Las caries en la dentición temporal y permanente fueron relativamente menores que las observaciones publicadas por otros estudios en México. Los resultados confirmaron que la caries en la dentición temporal se asoció fuertemente con la caries en la dentición permanente. No hubo una relación significativa entre las fuentes de fluoruro y la caries dental en la dentición permanente.Objective: To examine the relationship between the presence of enamel defects, dental caries in primary teeth, and exposure to various fluoride technologies and the presence of dental caries in permanent teeth in children with mixed dentition. Materials and methods: A cross-sectional study was conducted in 713 children aged 6-9 years old
Dental Enamel Development: Proteinases and Their Enamel Matrix Substrates
Bartlett, John D.
2013-01-01
This review focuses on recent discoveries and delves in detail about what is known about each of the proteins (amelogenin, ameloblastin, and enamelin) and proteinases (matrix metalloproteinase-20 and kallikrein-related peptidase-4) that are secreted into the enamel matrix. After an overview of enamel development, this review focuses on these enamel proteins by describing their nomenclature, tissue expression, functions, proteinase activation, and proteinase substrate specificity. These proteins and their respective null mice and human mutations are also evaluated to shed light on the mechanisms that cause nonsyndromic enamel malformations termed amelogenesis imperfecta. Pertinent controversies are addressed. For example, do any of these proteins have a critical function in addition to their role in enamel development? Does amelogenin initiate crystallite growth, does it inhibit crystallite growth in width and thickness, or does it do neither? Detailed examination of the null mouse literature provides unmistakable clues and/or answers to these questions, and this data is thoroughly analyzed. Striking conclusions from this analysis reveal that widely held paradigms of enamel formation are inadequate. The final section of this review weaves the recent data into a plausible new mechanism by which these enamel matrix proteins support and promote enamel development. PMID:24159389
Knots in homology spheres which have simple knot Floer homology are trivial
Eftekhary, Eaman
2010-01-01
We show that if K is a non-trivial knot inside a homology sphere X, the rank of the knot Floer homology group associated with K is strictly bigger than the rank of the Heegaard Floer homology group associated with X.
Fluoride varnishes and enamel caries
Bruyn, Hugo de
1987-01-01
Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical appl
Fluoride varnishes and enamel caries
Bruyn, Hugo de
1987-01-01
Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical
Legendrian and transverse cables of positive torus knots
Etnyre, John; LaFountain, Douglas; Tosun, Bülent
2012-01-01
In this paper we classify Legendrian and transverse knots in the knot types obtained from positive torus knots by cabling. This classification allows us to demonstrate several new phenomena. Specifically, we show there are knot types that have non-destabilizable Legendrian representatives whose...... Thurston-Bennequin invariant is arbitrarily far from maximal. We also exhibit Legendrian knots requiring arbitrarily many stabilizations before they become Legendrian isotopic. Similar new phenomena are observed for transverse knots. To achieve these results we define and study "partially thickenable" tori...
Origin of Metastable Knots in Single Flexible Chains
Dai, Liang; Renner, C. Benjamin; Doyle, Patrick S.
2015-01-01
Recent theoretical progress has explained the physics of knotting of semiflexible polymers, yet knotting of flexible polymers is relatively unexplored. We herein develop a new theory for the size distribution of knots on a flexible polymer and the existence of metastable knots. We show the free energy of a flexible molecule in a tube can be mapped to quantitatively reproduce the free energy distribution of a knot on a flexible chain. The size distribution of knots on flexible chains is expected to be universal and might be observed at a macroscopic scale, such as a string of hard balls.
Comparing models of Red Knot population dynamics
McGowan, Conor
2015-01-01
Predictive population modeling contributes to our basic scientific understanding of population dynamics, but can also inform management decisions by evaluating alternative actions in virtual environments. Quantitative models mathematically reflect scientific hypotheses about how a system functions. In Delaware Bay, mid-Atlantic Coast, USA, to more effectively manage horseshoe crab (Limulus polyphemus) harvests and protect Red Knot (Calidris canutus rufa) populations, models are used to compare harvest actions and predict the impacts on crab and knot populations. Management has been chiefly driven by the core hypothesis that horseshoe crab egg abundance governs the survival and reproduction of migrating Red Knots that stopover in the Bay during spring migration. However, recently, hypotheses proposing that knot dynamics are governed by cyclical lemming dynamics garnered some support in data analyses. In this paper, I present alternative models of Red Knot population dynamics to reflect alternative hypotheses. Using 2 models with different lemming population cycle lengths and 2 models with different horseshoe crab effects, I project the knot population into the future under environmental stochasticity and parametric uncertainty with each model. I then compare each model's predictions to 10 yr of population monitoring from Delaware Bay. Using Bayes' theorem and model weight updating, models can accrue weight or support for one or another hypothesis of population dynamics. With 4 models of Red Knot population dynamics and only 10 yr of data, no hypothesis clearly predicted population count data better than another. The collapsed lemming cycle model performed best, accruing ~35% of the model weight, followed closely by the horseshoe crab egg abundance model, which accrued ~30% of the weight. The models that predicted no decline or stable populations (i.e. the 4-yr lemming cycle model and the weak horseshoe crab effect model) were the most weakly supported.
Multispecies modeling for adaptive management of horseshoe crabs and red knots in the Delaware Bay
McGowan, Conor P.; Smith, David; Sweka, John A.; Martin, Julien; Nichols, James D.; Wong, Richard; Lyons, James E.; Niles, Lawrence J.; Kalasz, Kevin; Brust, Jeffrey; Klopfer, Michelle; Spear, Braddock
2011-01-01
Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species.
The inner knot of the Crab nebula
Lyutikov, Maxim; Porth, Oliver
2015-01-01
We model the inner knot of the Crab Nebula as a synchrotron emission coming from the non-spherical MHD termination shock of relativistic pulsar wind. The post-shock flow is mildly relativistic; as a result the Doppler-beaming has a strong impact on the shock appearance. The model can reproduce the knot location, size, elongation, brightness distribution, luminosity and polarization provided the effective magnetization of the section of the pulsar wind producing the knot is low, $\\sigma \\leq 1$. In the striped wind model, this implies that the striped zone is rather wide, with the magnetic inclination angle of the Crab pulsar $\\ge 45^\\circ$; this agrees with the previous model-dependent estimate based on the gamma-ray emission of the pulsar. We conclude that the tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock and that this shock is a site of efficient particle acceleration. On the other hand, the deduced low magnetization of the knot plasma implies that this i...
The inner knot of the Crab nebula
Lyutikov, Maxim; Komissarov, Serguei S.; Porth, Oliver
2016-02-01
We model the inner knot of the Crab nebula as a synchrotron emission coming from the non-spherical MHD termination shock of relativistic pulsar wind. The post-shock flow is mildly relativistic; as a result the Doppler beaming has a strong impact on the shock appearance. The model can reproduce the knot location, size, elongation, brightness distribution, luminosity and polarization provided the effective magnetization of the section of the pulsar wind producing the knot is low, σ ≤ 1. In the striped wind model, this implies that the striped zone is rather wide, with the magnetic inclination angle of the Crab pulsar ≥45°; this agrees with the previous model-dependent estimate based on the gamma-ray emission of the pulsar. We conclude that the tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock and that this shock is a site of efficient particle acceleration. On the other hand, the deduced low magnetization of the knot plasma implies that this is an unlikely site for the Crab's gamma-ray flares, if they are related to the fast relativistic magnetic reconnection events.
Symmetries in proteins: A knot theory approach
Chen, Shi-Jie; Dill, Ken A.
1996-04-01
Whereas the symmetries of small molecules are described by the methods of group theory, there is no corresponding way to describe the complex symmetries in proteins. We develop a quantitative method to define and classify symmetries in compact polymers, based on the mathematical theory of graphs and knots. We represent different chain folds by their ``polymer graphs,'' equivalent to contact maps. We transform those graphs into mathematical knots to give a parsing of different possible chain folds into conformational taxonomies. We use Alexander-Conway knot polynomials to characterize the knots. We find that different protein structures with the same tertiary fold, e.g., a βαβ motif with different lengths of α helix and β sheet, can be described in terms of the different powers of the propagation matrices of the knot polynomial. This identifies a fundamental type of topological length invariance in proteins, ``elongatable'' symmetries. For example, ``helix,'' ``sheet,'' ``helix-turn-helix,'' and other secondary, supersecondary, and tertiary structures define structures of any chain length. Possibly the nine superfolds identified by Thornton et al. have elongatable symmetries.
The recurrent true umbilical cord knots: a case report
I Naghi
2012-11-01
Full Text Available Background: True umbilical cord knot is one of the abnormalities of the umbilical cord. Active fetal movements create cord knotting. True umbilical cord knots are rare but may be associated with fetal distress and stillbirth. True umbilical cord knots are capable of impeding blood flow to the fetus.Case presentation: A 26-year old primigravid woman was first treated for genital herpes simplex virus (HSV type 2 at 36 weeks of gestational age. She received oral acyclovir (400 mg three times daily for 10 days. At the gestational age of 38 weeks and 5 days, fetal activity decreased and NST was nonreactive. She was delivered by cesarean section and a true umbilical cord knot was found. Four years later, in her second pregnancy, another true knot was seen.Conclusion: Excessively long umbilical cords are more likely to be associated with true knots. Genetics has an important role in determining cord length and occurrence of true knots.
Representations of Knot Groups and Twisted Alexander Polynomials
Xiao Song LIN
2001-01-01
We present a twisted version of the Alexander polynomial associated with a matrix representation of the knot group. Examples of two knots with the same Alexander module but differenttwisted Alexander polynomials are given.
Knot solitons in the AFZ model
Ren Ji-Rong; Mo Shu-Fan; Zhu Tao
2009-01-01
This paper studies the topological properties of knotted solitons in the (3 + 1)-dimensional Aratyn-Ferreira-Zimerman (AFZ) model. Topologically, these solitons are characterized by the Hopf invariant I, which is an integral class in the homotopy group π3(S3)= Z. By making use of the decomposition of U(1) gauge potential theory and Duan's topological current theory, it is shown that the invariant is just the total sum of all the self-linking and linking numbers of the knot family while only linking numbers are considered in other papers. Furthermore, it is pointed out that this invariant is preserved in the branch processes (splitting, merging and intersection) of these knot vortex lines.
Nonlinear electrodynamics is skilled with knots
Goulart, E.
2016-07-01
The aim of this letter is threefold: First is to show that nonlinear generalizations of electrodynamics support various types of knotted solutions in vacuum. The solutions are universal in the sense that they do not depend on the specific Lagrangian density, at least if the latter gives rise to a well-posed theory. Second, is to describe the interaction between probe waves and knotted background configurations. We show that the qualitative behaviour of this interaction may be described in terms of Robinson congruences, which appear explicitly in the causal structure of the theory. Finally, we argue that optical arrangements endowed with intense background fields could be the natural place to look for the knots experimentally.
Nonlinear electrodynamics is skilled with knots
Goulart, E
2016-01-01
The aims of this letter are three-fold: First is to show that nonlinear generalizations of electrodynamics support various types of knotted solutions in vacuum. The solutions are universal in the sense that they do not depend on the specific Lagrangian density, at least if the latter gives rise to a well-posed theory. Second is to describe the interaction between probe waves and knotted background configurations. We show that the qualitative behaviour of this interaction may be described in terms of Robinson congruences, which appear explicitly in the causal structure of the theory. Finally, we argue that optical arrangements endowed with intense background fields could be the natural place to look for the knots experimentally.
On the concordance genus of topologically slice knots
Hom, Jennifer
2012-01-01
The concordance genus of a knot K is the minimum Seifert genus of all knots smoothly concordant to K. Concordance genus is bounded below by the 4-ball genus and above by the Seifert genus. We give a lower bound for the concordance genus of K coming from the knot Floer complex of K. As an application, we prove that there are topologically slice knots with 4-ball genus equal to one and arbitrarily large concordance genus.
Porcelain enamel neutron absorbing material
Iverson, Daniel C.
1990-01-01
A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.
Gostynska, Katarzyna B.; Yuen, Wing Yan; Pasmooij, Anna Maria Gerdina; Stellingsma, Cornelius; Pas, Hendri H.; Lemmink, Henny; Jonkman, Marcel F.
2017-01-01
The hereditary blistering disease junctional epidermolysis bullosa (JEB) is always accompanied by structural enamel abnormalities of primary and secondary dentition, characterized as amelogenesis imperfecta. Autosomal recessive mutations in LAMA3, LAMB3 and LAMC2 encoding the heterotrimer laminin
Knot invariants and higher representation theory II: the categorification of quantum knot invariants
Webster, Ben
2010-01-01
We construct knot invariants categorifying the quantum knot variants for all representations of quantum groups. We show that these invariants coincide with previous invariants defined by Khovanov for sl_2 and sl_3 and by Mazorchuk-Stroppel and Sussan for sl_n. We also suggest an approach to showing that these knot homologies are functorial. Our technique uses categorifications of the tensor products of integrable representations of Kac-Moody algebras and quantum groups, constructed a prequel to this paper. In particular, we construct functors on these categorifying the action of the braiding and duality of quantum group representations. These categories are based on the pictorial approach of Khovanov and Lauda.
A principle for ideal torus knots
Olsen, Kasper Wibeck; Bohr, Jakob
2013-01-01
Using bent-helix embeddings, we investigate simple and knotted torus windings that are made of tubes of finite thickness. Knots which have the shortest rope length are often denoted as ideal structures. Conventionally, the ideal structures are found by rope shortening routines. It is shown...... that alternatively they can be directly determined as maximally twisted structures. In many cases these structures are also structures with zero strain-twist coupling, i.e. structures that neither rotate one or the other way under strain. We use this principle to implement rapid numerical calculations of the ideal...
On Chebyshev polynomials and torus knots
Gavrilik, A. M.; Pavlyuk, A. M.
2009-01-01
In this work we demonstrate that the q-numbers and their two-parameter generalization, the q,p-numbers, can be used to obtain some polynomial invariants for torus knots and links. First, we show that the q-numbers, which are closely connected with the Chebyshev polynomials, can also be related with the Alexander polynomials for the class T(s,2) of torus knots, s being an odd integer, and used for finding the corresponding skein relation. Then, we develop this procedure in order to obtain, wit...
Knotted strings and leptonic flavor structure
Kephart, Thomas W; Päs, Heinrich
2011-01-01
Tight knots and links arising in the infrared limit of string theories may provide an interesting alternative to flavor symmetries for explaining the observed flavor patterns in the leptonic sector. As an example we consider a type I seesaw model where the Majorana mass structure is based on the discrete length spectrum of tight knots and links. It is shown that such a model is able to provide an excellent fit to current neutrino data and that it predicts a normal neutrino mass hierarchy as well as a small mixing angle $\\theta_{13}$.
Universal Form of Renormalizable Knots in Symbolic Dynamics
GAO Wen; PENG Shou-Li
2005-01-01
@@ The knot structure of three-dimensional flow has been constructed based on minimal braid assumption [Chin. Phys. Lett. 20 (2003) 1444]. Here we provide a new universal form of renormalizable knots. From this universal form an arbitrary renormalizable knot can be decomposed into a unique set of elementary templates.
Knotcraft the practical and entertaining art of tying knots
Macfarlan, Allan and Paulette
1983-01-01
Comprehensive reference work explains how to tie hundreds of practical (and decorative) knots in clear illustrations and precisely worded written instructions. Ideal for boaters and campers. Also covers knots in history, knot mystery and magic, and games, stunts and tricks with rope. Introduction. Index. 166 black-and-white illustrations.
On slope genera of knotted tori in the 4-space
Liu, Yi; Sun, Hongbin; Wang, Shicheng
2011-01-01
In this note, we investigate genera for the slopes of a knotted torus in the 4-sphere analogous to the genus of a classical knot. We compare various formulations of this notion, and use this notion to study the extendable subgroup of the mapping class group of the knotted torus.
Refined large N duality for torus knots
Nawata, Satoshi; Kameyama, Masaya
We formulate large N duality of U(N) refined Chern-Simons theory with a torus knot/link in S³. By studying refined BPS states in M-theory, we provide the explicit form of low-energy effective actions of Type IIA string theory with D4-branes on the Ω-background. This form enables us to relate...
Four-manifolds, geometries and knots
Hillman, Jonathan A
2007-01-01
The goal of this book is to characterize algebraically the closed 4-manifolds that fibre nontrivially or admit geometries in the sense of Thurston, or which are obtained by surgery on 2-knots, and to provide a reference for the topology of such manifolds and knots. The first chapter is purely algebraic. The rest of the book may be divided into three parts: general results on homotopy and surgery (Chapters 2-6), geometries and geometric decompositions (Chapters 7-13), and 2-knots (Chapters 14-18). In many cases the Euler characteristic, fundamental group and Stiefel-Whitney classes together form a complete system of invariants for the homotopy type of such manifolds, and the possible values of the invariants can be described explicitly. The strongest results are characterizations of manifolds which fibre homotopically over S^1 or an aspherical surface (up to homotopy equivalence) and infrasolvmanifolds (up to homeomorphism). As a consequence 2-knots whose groups are poly-Z are determined up to Gluck reconstruc...
Kontsevich integral for knots and Vassiliev invariants
Dunin-Barkowski, P.; Sleptsov, A.; Smirnov, A.
2013-01-01
We review quantum field theory approach to the knot theory. Using holomorphic gauge, we obtain the Kontsevich integral. It is explained how to calculate Vassiliev invariants and coefficients in Kontsevich integral in a combinatorial way which can be programmed on a computer. We discuss experimental
The constrictor knot is the best ligature.
Taylor, H; Grogono, A W
2014-03-01
An ideal ligature should tighten readily and remain tight. Ligature failure can be a critical complication of invasive procedures in human and veterinary surgical practice. Previous studies have tested various knots but not the constrictor knot. A new test bench was employed to compare six ligatures using four suture materials. As tension in a ligature is not readily measured, the study employed a surrogate measurement: the force required to slide a ligature along a rod. Benchmark values tested each suture material wrapped around the rod to establish the ratio between this force and the ligature tension for each material. Each ligature was tested first during tightening and then again afterwards. The benchmark ratios were employed to calculate the tensions to evaluate which ligature and which suture material retained tension best. The model provided consistent linear relationships between the tension in the suture and the force required to pull the ligature along the rod. The constrictor knot retained tension in the ligature best (55-107% better than the next best ligature). Among the suture materials, polydioxanone had the greatest ability to retain the tension in a ligature and polyglactin the least. The constrictor knot showed superior characteristics for use as a ligature, and should be introduced into teaching and clinical practice for human and veterinary surgery. The new test bench is recommended for future testing of ligatures as well as objective comparison of suture materials.
Refined large N duality for torus knots
Nawata, Satoshi; Kameyama, Masaya
We formulate large N duality of U(N) refined Chern-Simons theory with a torus knot/link in S³. By studying refined BPS states in M-theory, we provide the explicit form of low-energy effective actions of Type IIA string theory with D4-branes on the Ω-background. This form enables us to relate...
A preliminary design of a knot undulator.
Xi, Fuchun; Shi, Tan; Fan, Qingyan; Prestemon, Soren; Wan, Weishi; An, Zhenghua; Qiao, S
2013-01-01
The magnetic field configuration of the previously proposed knot undulator [Qiao et al. (2009). Rev. Sci. Instrum. 80, 085108] is realised in the design of a hybridized elliptically polarized undulator, which is presented. Although the details of the field distribution are not the same as those in the theoretical proposal, it is demonstrated that the practical knot undulator could work perfectly. In order to understand the minor discrepancies of the two, mathematical formulae of the synchrotron radiation are derived based on the Fourier transform of the magnetic field. From the results of calculations by simulation program, the discrepancies could be well interpreted by the corresponding formulae. The results show the importance of optimization of the end sections of the knot undulator to suppress the on-axis heat load. Furthermore, a study of the impact of the undulator on beam dynamics of the storage ring was conducted using the Shanghai Synchrotron Radiation Facility as an example and the results show that the knot undulator has little effect on the beam.
Colored HOMFLY polynomials can distinguish mutant knots
Nawata, Satoshi; Singh, Vivek Kumar
2015-01-01
We illustrate from the viewpoint of braiding operations on WZNW conformal blocks how colored HOMFLY polynomials with multiplicity structure can detect mutations. As an example, we explicitly evaluate the (2,1)-colored HOMFLY polynomials that distinguish a famous mutant pair, Kinoshita-Terasaka and Conway knot.
Radio continuum emission from knots in the DG Tau jet
Rodriguez, L F; Raga, A C; Canto, J; Riera, A; Loinard, L; Dzib, S A; Zapata, L A
2011-01-01
Context: HH 158, the jet from the young star DG Tau, is one of the few sources of its type where jet knots have been detected at optical and X-ray wavelengths. Aims: To search, using Very Large Array observations of this source, radio knots and if detected, compare them with the optical and X-ray knots. To model the emission from the radio knots. Methods: We analyzed archive data and also obtained new Very Large Array observations of this source, as well as an optical image, to measure the present position of the knots. We also modeled the radio emission from the knots in terms of shocks in a jet with intrinsically time-dependent ejection velocities. Results: We detected radio knots in the 1996.98 and 2009.62 VLA data. These radio knots are,within error, coincident with optical knots. We also modeled satisfactorily the observed radio flux densities as shock features from a jet with intrinsic variability. All the observed radio, optical, and X-ray knot positions can be intepreted as four successive knots, ejec...
Effect of knots on binding of intercalators to DNA
Medalion, Shlomi; Rabin, Yitzhak
2014-05-01
We study the effect of knots in circular dsDNA molecules on the binding of intercalating ligands. Using Monte Carlo simulations we show that depending on their handedness, the presence of knots can either suppress or enhance intercalation in supercoiled DNA. When the occupancy of intercalators on DNA is low, the effect of knots on intercalation can be captured by introducing a shift in the mean writhe of the chain that accounts for the writhe of the corresponding ideal knot. In the limit of high intercalator occupancy, the writhe distribution of different knots is strongly affected by excluded volume effects and therefore by salt concentration. Based on the finding that different knots yield well-separated probability distributions of bound intercalators, we propose a new experimental approach to determine DNA topology by monitoring the intensity of fluorescence emitted by dye molecules intercalated into knotted DNA molecules.
An association of external and internal enamel pearls.
Mahajan S; Charan C
2005-01-01
We report a rare case of an association of external enamel pearl with internal enamel pearl on the root of a molar. To the best of our knowledge, association of external and internal enamel pearls has not been previously reported. We discussed the histogenesis of enamel pearls and proposed that internal enamel pearl formation may be a continuation of formation of external enamel pearl.
Enamel Regeneration in Making a Bioengineered Tooth.
Xu, Ruoshi; Zhou, Yachuan; Zhang, Binpeng; Shen, Jiefei; Gao, Bo; Xu, Xin; Ye, Ling; Zheng, Liwei; Zhou, Xuedong
2015-01-01
Overall enamel is the hard tissue overlying teeth that is vulnerable to caries, congenital defects, and damage due to trauma. Not only is enamel incapable of self-repair in most species, but it is also subject to attrition. Besides the use of artificial materials to restore enamel, enamel regeneration is a promising approach to repair enamel damage. In order to comprehend the progression and challenges in tissue-engineered enamel, this article elaborates alternative stem cells potential for enamel secretion and expounds fined strategies for enamel regeneration in bioengineered teeth. Consequently, more and more cell types have been induced to differentiate into ameloblasts and to secrete enamel, and an increasing number of reports have emerged to provide various potential approaches to induce cells to secrete enamel based on recombination experiments, artificial bioactive nano-materials, or gene manipulation. Accordingly, it is expected to further project more optimal conditions for enamel formation in bioengineering based on a more thorough knowledge of reciprocal epithelial-mesenchymal interactions, by which the procedures of enamel regeneration are able to be practically recapitulated and widely spread for the potential clinical value of enamel repair.
Mathew Renu Ann
2013-01-01
.... Esthetic restoration of primary anterior teeth can be especially challenging due to the small size of the teeth, close proximity of pulp to tooth surface, relatively thin enamel and surface area...
Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study.
Charone, Senda; Portela, Maristela Barbosa; Martins, Karol de Oliveira; Soares, Rosangela Maria; Castro, Gloria Fernanda
2017-01-01
This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+) children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH), Polarized Light Microscopy (PLM) and the quantity of calcium ions (Ca2+) released from the enamel. Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140) enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1); mixed biofilm formed by C. albicans and C. tropicalis (Group 2); mixed biofilm formed by C. albicans and C. parapsilosis (Group 3); mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4); biofilm formed by C. albicans ATCC (Group 5) and medium without Candida (Group 6). Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca2+ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%. TMH showed a gradual reduction in enamel hardness (pCandida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro.
Surface-knots in 4-space an introduction
Kamada, Seiichi
2017-01-01
This introductory volume provides the basics of surface-knots and related topics, not only for researchers in these areas but also for graduate students and researchers who are not familiar with the field. Knot theory is one of the most active research fields in modern mathematics. Knots and links are closed curves (one-dimensional manifolds) in Euclidean 3-space, and they are related to braids and 3-manifolds. These notions are generalized into higher dimensions. Surface-knots or surface-links are closed surfaces (two-dimensional manifolds) in Euclidean 4-space, which are related to two-dimensional braids and 4-manifolds. Surface-knot theory treats not only closed surfaces but also surfaces with boundaries in 4-manifolds. For example, knot concordance and knot cobordism, which are also important objects in knot theory, are surfaces in the product space of the 3-sphere and the interval. Included in this book are basics of surface-knots and the related topics of classical knots, the motion picture method, surf...
Sasagawa, I; Ferguson, M W
1991-01-01
In Monodelphis domestica, although both processes from odontoblasts and projections from ameloblasts were found in developing enamel, the majority of the contents of enamel tubules were probably processes that originated from odontoblasts. Processes from odontoblasts penetrating into enamel touched part of the ameloblasts in the stage of enamel formation. No specialised cell junctions were seen at the adherence between the two. There were no enamel tubules in the aprismatic and pseudoprismati...
A note on colored HOMFLY polynomials for hyperbolic knots from WZW models
Gu, Jie
2014-01-01
Using the correspondence between Chern-Simons theories and Wess-Zumino-Witten models we present the necessary tools to calculate colored HOMFLY polynomials for hyperbolic knots. For two-bridged hyperbolic knots we derive the colored HOMFLY invariants in terms of crossing matrices of the underlying Wess-Zumino-Witten model. Our analysis extends previous works by incorporating non-trivial multiplicities for the primaries appearing in the crossing matrices, so as to describe colorings of HOMFLY invariants beyond the totally symmetric or anti-symmetric representations of SU(N). The crossing matrices directly relate to 6j-symbols of the quantum group U_q(su(N)). We present powerful methods to calculate such quantum 6j-symbols for general N. This allows us to explicitly determine previously unknown colored HOMFLY polynomials for all two-bridged hyperbolic knots. Yet, the scope of application of our techniques goes beyond knot theory; e.g., our findings can be used to study correlators in Wess-Zumino-Witten conforma...
Enamel renal syndrome: A rare case report
S V Kala Vani
2012-01-01
Full Text Available Enamel renal syndrome is a very rare disorder associating amelogenesis imperfecta with nephrocalcinosis. It is known by various synonyms such as amelogenesis imperfecta nephrocalcinosis syndrome, MacGibbon syndrome, Lubinsky syndrome, and Lubinsky-MacGibbon syndrome. It is characterized by enamel agenesis and medullary nephrocalcinosis. This paper describes enamel renal syndrome in a female patient born in a consanguineous family.
On Chebyshev polynomials and torus knots
Gavrilik, A M
2009-01-01
In this work we demonstrate that the q-numbers and their two-parameter generalization, the q,p-numbers, can be used to obtain some polynomial invariants for torus knots and links. First, we show that the q-numbers, which are closely connected with the Chebyshev polynomials, can also be related with the Alexander polynomials for the class T(s,2) of torus knots, s being an odd integer, and used for finding the corresponding skein relation. Then, we develop this procedure in order to obtain, with the help of q,p-numbers, the generalized two-variable Alexander polynomials, and prove their direct connection with the HOMFLY polynomials and the skein relation of the latter.
Towards effective topological field theory for knots
Mironov, A
2015-01-01
Construction of (colored) knot polynomials for double-fat graphs is further generalized to the case when "fingers" and "propagators" are substituting R-matrices in arbitrary closed braids with m-strands. Original version of arXiv:1504.00371 corresponds to the case m=2, and our generalizations sheds additional light on the structure of those mysterious formulas. Explicit expressions are now combined from Racah matrices of the type $R\\otimes R\\otimes\\bar R\\longrightarrow \\bar R$ and mixing matrices in the sectors $R^{\\otimes 3}\\longrightarrow Q$. Further extension is provided by composition rules, allowing to glue two blocks, connected by an m-strand braid (they generalize the product formula for ordinary composite knots with m=1).
Induction effects of torus knots and unknots
Oberti, Chiara; Ricca, Renzo L.
2017-09-01
Geometric and topological aspects associated with induction effects of field lines in the shape of torus knots/unknots are examined and discussed in detail. Knots are assumed to lie on a mathematical torus of circular cross-section and are parametrized by standard equations. The induced field is computed by direct integration of the Biot-Savart law. Field line patterns of the induced field are obtained and several properties are examined for a large family of knots/unknots up to 51 crossings. The intensity of the induced field at the origin of the reference system (center of the torus) is found to depend linearly on the number of toroidal coils and reaches maximum values near the boundary of the mathematical torus. New analytical estimates and bounds on energy and helicity are established in terms of winding number and minimum crossing number. These results find useful applications in several contexts when the source field is either vorticity, electric current or magnetic field, from vortex dynamics to astrophysics and plasma physics, where highly braided magnetic fields and currents are present.
Modeling the Effects of Knots in Structural Timber
Foley, Christina
was established, which describes variations of radial growth direction and fiber orientation related to knots in timber. The adaptability of the paradigm allows practically any softwood knot and its effect on surrounding wood material to be modeled with an accuracy that is limited only by input data. The knot......The main purpose of the pursued research presented in this thesis is to increase knowledge of the effects of knots in structural timber so that characteristics of weaker timber may be determined and applied to improve current grading techniques. In the process, a three-dimensional fiber paradigm...... are given to Shigo's knot formation theory, and thus predicts two separate patterns of fiber direction within annual growth layers related to live knots. In order to determine the possibility to practically and non destructively predict local material directions in structural timber with the three...
Factorization of differential expansion for antiparallel double-braid knots
Morozov, A
2016-01-01
Continuing the quest for exclusive Racah matrices, which are needed for evaluation of colored arborescent-knot polynomials in Chern-Simons theory, we suggest to extract them from a new kind of a double-evolution -- that of the antiparallel double-braids, which is a simple two-parametric family of two-bridge knots, generalizing the one-parametric family of twist knots. In the case of rectangular representations $R=[r^s]$ we found an evidence that the corresponding differential expansion miraculously factorizes and can be obtained from that for the twist knots. This reduces the problem of rectangular exclusive Racah to constructing the answers for just a few twist knots. We develop a recent conjecture on the structure of differential expansion for the simplest members of this family -- the trefoil and the figure-eight knot,-- but manage to guess the full answer only for contributions of single-floor pyramids. One step still remains to be done.
Comar, Lívia P; Souza, Beatriz M; Al-Ahj, Luana P; Martins, Jessica; Grizzo, Larissa T; Piasentim, Isabelle S; Rios, Daniela; Buzalaf, Marília Afonso Rabelo; Magalhães, Ana Carolina
2017-10-12
This in vitro study aimed to evaluate the action of TiF4 on sound and carious bovine and human enamel. Sound (S) and pre-demineralised (DE) bovine and human (primary and permanent) enamel samples were treated with TiF4 (pH 1.0) or NaF varnishes (pH 5.0), containing 0.95, 1.95, or 2.45% F for 12 h. The enamel surfaces were analysed using SEM-EDX (scanning electron microscopy/energy-dispersive X-ray spectroscopy) (n = 10, 5 S and 5 DE) and KOH-soluble fluoride was quantified (n = 20, 10 S and 10 DE). Hydroxyapatite powder produced by precipitation method was treated with the corresponding fluoride solutions for 1 min (n = 2). The formed compounds were detected using X-ray diffraction (XRD). All TiF4 varnishes produced a coating layer rich in Ti and F on all types of enamel surface, with micro-cracks in its extension. TiF4 (1.95 and 2.45% F) provided higher fluoride deposition than NaF, especially for bovine enamel (p enamel. The Ti content was higher for bovine and human primary enamel than human permanent enamel, with some differences between S and DE. The XRD analysis showed that TiF4 induced the formation of new compounds such as CaF2, TiO2, and Ti(HPO4)2·H2O. In conclusion, TiF4 (>0.95% F) interacts better, when compared to NaF, with bovine and human primary enamel than with human permanent enamel. TiF4 provoked higher F deposition compared to NaF. Carious enamel showed higher F uptake than sound enamel by TiF4 application, while Ti uptake was dependent on the enamel condition and origin. © 2017 S. Karger AG, Basel.
Cocycle Knot Invariants, Quandle Extensions, and Alexander Matrices
2002-01-01
The theory of quandle (co)homology and cocycle knot invariants is rapidly being developed. We begin with a summary of these recent advances. One such advance is the notion of a dynamical cocycle. We show how dynamical cocycles can be used to color knotted surfaces that are obtained from classical knots by twist-spinning. We also demonstrate relations between cocycle invariants and Alexander matrices.
Prevalence of enamel defects and association with dental caries in preschool children.
Massignan, C; Ximenes, M; da Silva Pereira, C; Dias, L; Bolan, M; Cardoso, M
2016-12-01
This was to evaluate the prevalence of the developmental defects of enamel (DDE) in primary teeth and its association with dental caries. A cross-sectional study with a randomised representative sample was carried out with 1101 children aged 2-5 years enrolled in public preschools (50% prevalence of DDE in primary teeth, a standard error of 3%, and a confidence level of 95%). Three calibrated dentists (K > 0.62) performed clinical examination. Data collected were: sex, age, DDE (Modified DDE Index) and dental caries (WHO). Descriptive analysis, Chi-square test and multinomial logistic regression were applied for data analysis. Among children, 565 (51.3%) were boys; mean age was 3.7 (±0.9 years). The prevalence of enamel defect was 39.1%; the prevalence of diffuse opacities, demarcated opacities and enamel hypoplasia was 25.3, 19.1 and 6.1%, respectively. The prevalence of dental caries was 31.0%, with mean def-t 1.14 (±2.44). Primary teeth with enamel hypoplasia had three times the odds of having dental caries than those with absence of enamel defects (OR = 3.10; 95% CI: 1.91, 5.01). The presence of enamel defects was moderate and associated with dental caries.
Large N duality, lagrangian cycles, and algebraic knots
Diaconescu, D -E; Vafa, C
2011-01-01
We consider knot invariants in the context of large $N$ transitions of topological strings. In particular we consider aspects of Lagrangian cycles associated to knots in the conifold geometry. We show how these can be explicity constructed in the case of algebraic knots. We use this explicit construction to explain a recent conjecture relating study of stable pairs on algebraic curves with HOMFLY polynomials. Furthermore, for torus knots, using the explicit construction of the Lagrangian cycle, we also give a direct A-model computation and recover the HOMFLY polynomial for this case.
Large N Duality, Lagrangian Cycles, and Algebraic Knots
Diaconescu, D.-E.; Shende, V.; Vafa, C.
2013-05-01
We consider knot invariants in the context of large N transitions of topological strings. In particular we consider aspects of Lagrangian cycles associated to knots in the conifold geometry. We show how these can be explicitly constructed in the case of algebraic knots. We use this explicit construction to explain a recent conjecture relating study of stable pairs on algebraic curves with HOMFLY polynomials. Furthermore, for torus knots, using the explicit construction of the Lagrangian cycle, we also give a direct A-model computation and recover the HOMFLY polynomial for this case.
Classical invariants of Legendrian knots in the 3-dimensional torus
SJ, Paul A. Schweitzer; Souza, Fábio S.
2014-01-01
All knots in $R^3$ possess Seifert surfaces, and so the classical Thurston-Bennequin and rotation (or Maslov) invariants for Legendrian knots in a contact structure on $R^3$ can be defined. The definitions extend easily to null-homologous knots in any $3$-manifold $M$ endowed with a contact structure $\\xi$. We generalize the definition of Seifert surfaces and use them to define these invariants for all Legendrian knots, including those that are not null-homologous, in a contact structure on t...
Store-operated Ca2+ Entry Modulates the Expression of Enamel Genes.
Nurbaeva, M K; Eckstein, M; Snead, M L; Feske, S; Lacruz, R S
2015-10-01
Dental enamel formation is an intricate process tightly regulated by ameloblast cells. The correct spatiotemporal patterning of enamel matrix protein (EMP) expression is fundamental to orchestrate the formation of enamel crystals, which depend on a robust supply of Ca2+. In the extracellular milieu, Ca2+ -EMP interactions occur at different levels. Despite its recognized role in enamel development, the molecular machinery involved in Ca2+ homeostasis in ameloblasts remains poorly understood. A common mechanism for Ca2+ influx is store-operated Ca2+ entry (SOCE). We evaluated the possibility that Ca2+ influx in enamel cells might be mediated by SOCE and the Ca2+ release-activated Ca2+ (CRAC) channel, the prototypical SOCE channel. Using ameloblast-like LS8 cells, we demonstrate that these cells express Ca2+ -handling molecules and mediate Ca2+ influx through SOCE. As a rise in the cytosolic Ca2+ concentration is a versatile signal that can modulate gene expression, we assessed whether SOCE in enamel cells had any effect on the expression of EMPs. Our results demonstrate that stimulating LS8 cells or murine primary enamel organ cells with thapsigargin to activate SOCE leads to increased expression of Amelx, Ambn, Enam, Mmp20. This effect is reversed when cells are treated with a CRAC channel inhibitor. These data indicate that Ca2+ influx in LS8 cells and enamel organ cells is mediated by CRAC channels and that Ca2+ signals enhance the expression of EMPs. Ca2+ plays an important role not only in mineralizing dental enamel but also in regulating the expression of EMPs.
Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots
Kholodenko, Arkady L., E-mail: string@clemson.edu
2016-08-15
Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang–Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric–magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada’s results by carefully analyzing and classifying all dynamically generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].
Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots
Kholodenko, Arkady L.
2016-08-01
Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang-Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric-magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada's results by carefully analyzing and classifying all dynamically generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].
The effect of enamel proteins on erosion
Baumann, T.; Carvalho, T. S.; Lussi, A.
2015-01-01
Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p erosion, the progression of all three evaluated parameters differed significantly between the two groups (p erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur. PMID:26468660
Development Enamel Defects in Children Prenatally Exposed to Anti-Epileptic Drugs
Jacobsen, Pernille Endrup; Henriksen, Tine Brink; Haubek, Dorte
2013-01-01
Objective Some anti-epileptic drugs (AED) have well-known teratogenic effects. The aim of the present study was to elucidate the effect of prenatal exposure to AED and the risk of enamel defects in the primary and permanent dentition. Methods A total of 38 exposed and 129 non-exposed children, 6......–10 years of age, were recruited from the Aarhus Birth Cohort and the Department of Neurology, Viborg Regional Hospital, Denmark. Medication during pregnancy was confirmed by the Danish Prescription Database. All children had their teeth examined and outcomes in terms of enamel opacities and enamel...... hypoplasia were recorded. Results Children prenatally exposed to AED have an increased prevalence of enamel hypoplasia (11% vs. 4%, odds ratio (OR) = 3.6 [95% confidence interval (CI): 0.9 to 15.4]), diffuse opacities (18% vs. 7%, OR = 3.0; [95% CI: 1.0 to 8.7, p3) white opacities (18...
Knot polynomial identities and quantum group coincidences
Morrison, Scott; Snyder, Noah
2010-01-01
We construct link invariants using the D_2n subfactor planar algebras, and use these to prove new identities relating certain specializations of colored Jones polynomials to specializations of other quantum knot polynomials. These identities can also be explained by coincidences between small modular categories involving the even parts of the D_2n planar algebras. We discuss the origins of these coincidences, explaining the role of SO level-rank duality, Kirby-Melvin symmetry, and properties of small Dynkin diagrams. One of these coincidences involves G_2 and does not appear to be related to level-rank duality.
Root-knot nematode resistant rootstocks for grafted watermelon
Rootstock lines of wild watermelon (Citrullus lanatus var. citroides) with resistance to root-knot nematodes (RKN) were developed by our team at the U.S. Vegetable Laboratory. Rootstock lines RKVL 301, RKVL 316, and RKVL 318 (RKVL = Root Knot Vegetable Laboratory) were compared to wild tinda (Praec...
Correspondence Between Bell Bases and Oriented Links in Knot Theory
QIAN ShangWu; GU ZhiYu
2002-01-01
From the comparison of correlation tensor in the theory of quantum network, the Alexander relation matrix in the theory of knot crystals and the identical inversion relations under the action of Pauli matrices, we show that there is a one to one correspondence between four Bell bases and four oriented links of the linkage 41 in knot theory.
Detection of Chirality and Mutations of Knots and Links
Pichai, Ramadevi
2011-01-01
In this brief presentation, we would like to present our attempts of detecting chirality and mutations from Chern-Simons gauge theory. The results show that the generalised knot invariants, obtained from Chern-Simons gauge theory, are more powerful than Jones, HOMFLYPT and Kauffman polynomials. However the classification problem of knots and links is still an open challenging problem.
Legendrian and transverse cables of positive torus knots
B. Etnyre, John; la Fountain, Douglas James; Tosun, Bulent
Thurston-Bennequin invariant is arbitrarily far from maximal. We also exhibit Legendrian knots requiring arbitrarily many stabilizations before they become Legendrian isotopic. Similar new phenomena are observed for transverse knots. To achieve these results we define and study "partially thickenable" tori...
Legendrian and transverse cables of positive torus knots
Etnyre, John; LaFountain, Douglas; Tosun, Bülent
2012-01-01
Thurston-Bennequin invariant is arbitrarily far from maximal. We also exhibit Legendrian knots requiring arbitrarily many stabilizations before they become Legendrian isotopic. Similar new phenomena are observed for transverse knots. To achieve these results we define and study "partially thickenable" tori...
Factorization of differential expansion for antiparallel double-braid knots
Morozov, A.
2016-09-01
Continuing the quest for exclusive Racah matrices, which are needed for evaluation of colored arborescent-knot polynomials in Chern-Simons theory, we suggest to extract them from a new kind of a double-evolution — that of the antiparallel double-braids, which is a simple two-parametric family of two-bridge knots, generalizing the one-parametric family of twist knots. In the case of rectangular representations R = [ r s ] we found an evidence that the corresponding differential expansion miraculously factorizes and can be obtained from that for the twist knots. This reduces the problem of rectangular exclusive Racah to constructing the answers for just a few twist knots. We develop a recent conjecture on the structure of differential expansion for the simplest members of this family (the trefoil and the figure-eight knot) and provide the exhaustive answer for the first unknown case of R = [33]. The answer includes HOMFLY of arbitrary twist and double-braid knots and Racah matrices overline{S} and S — what allows to calculate [33]-colored polynomials for arbitrary arborescent (double-fat) knots. For generic rectangular representations fully described are only the contributions of the single-floor pyramids. One step still remains to be done.
Studying uniform thickness II: Transversely nonsimple iterated torus knots
LaFountain, Douglas
2011-01-01
We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...
Genetic analysis of root-knot nematode resistance in potato
Draaistra, J.
2006-01-01
The development of potato varieties with resistance towards the potato cyst nematode, allowed a dramatic decrease of the use of nematicides. Subsequently the population of the free living nematodes and the root-knot nematodes ( Meloidogyne spp.) has increased. Among the root-knot nematodes, three Me
Arslan, Soley; Zorba, Yahya Orcun; Atalay, Mustafa Altay; Özcan, Suat; Demirbuga, Sezer; Pala, Kansad; Percin, Duygu; Ozer, Fusun
2015-01-01
The aim of this study was to evaluate and compare the effects of resin infiltration and sealant type on enamel surface properties and Streptococcus mutans adhesion to artificial enamel lesions. Artificial enamel lesions were produced on the surfaces of 120 enamel specimens, which were divided into two groups: Group A and Group B (n=60 per group). Each group was further divided into four subgroups (n=15 per subgroup) according to sealant type: Group I-Demineralized enamel (control); Group II-Enamel Pro Varnish; Group III-ExciTE F; and Group IV-Icon. In Group A, hardness and surface roughness were evaluated; in Group B, bacterial adhesion was evaluated. Icon application resulted in significantly lower surface roughness and higher hardness than the other subgroups in Group A. In Group B, Enamel Pro Varnish resulted in lowest bacterial adhesion, followed by Icon. This study showed that resin infiltration of enamel lesions could arrest lesion progress.
Extended knots and the space of states of quantum gravity
Griego, J R
1996-01-01
In the loop representation the quantum constraints of gravity can be solved. This fact allowed significant progress in the understanding of the space of states of the theory. The analysis of the constraints over loop dependent wavefunctions has been traditionally based upon geometric (in contrast to analytic) properties of the loops. The reason for this preferred way is twofold: for one hand the inherent difficulties associated with the analytic loop calculus, and on the other our limited knowledge about the analytic properties of knots invariants. Extended loops provide a way to overcome the difficulties at both levels. For one hand, a systematic method to construct analytic expressions of diffeomorphism invariants (the extended knots) in terms of the Chern-Simons propagators can be developed. Extended knots are simply related to ordinary knots (at least formally). The analytic expressions of knot invariants could be produced then in a generic way. On the other hand, the evaluation of the Hamiltonian over ex...
Relative symplectic caps, 4-genus and fibered knots
Siddhartha Gadgil; Dheeraj Kulkarni
2016-05-01
We prove relative versions of the symplectic capping theorem and sufficiency of Giroux’s criterion for Stein fillability and use these to study the 4-genus of knots. More precisely, suppose we have a symplectic 4-manifold with convex boundary and a symplectic surface in such that is a transverse knot in . In this paper, we prove that there is a closed symplectic 4-manifold with a closed symplectic surface such that (, ) embeds into (, ) symplectically. As a consequence we obtain a relative version of the symplectic Thom conjecture. We also prove a relative version of the sufficiency part of Giroux’s criterion for Stein fillability, namely, we show that a fibered knot whose mondoromy is a product of positive Dehn twists bounds a symplectic surface in a Stein filling. We use this to study 4-genus of fibered knots in $\\mathbb S^3$. Further, we give a criterion for quasipositive fibered knots to be strongly quasipositive.
Knot Solitons in Spinor Bose-Einstein Condensates
Hall, David; Ray, Michael; Tiurev, Konstantin; Ruokokoski, Emmi; Gheorghe, Andrei Horia; Möttönen, Mikko
2016-05-01
Knots are familiar entities that appear at a captivating nexus of art, technology, mathematics and science. Following a lengthy period of theoretical investigation and development, they have recently attracted great experimental interest in classical contexts ranging from knotted DNA and nanostructures to vortex knots in fluids. We demonstrate here the controlled creation and detection of knot solitons in the quantum-mechanical order parameter of a spinor Bose-Einstein condensate. Images of the superfluid reveal the circular shape of the soliton core and its associated linked rings. Our observations of the knot soliton establish an experimental foundation for future studies of their stability, dynamics and applications within quantum systems. Supported in part by NSF Grant PHY-1205822.
Knot polynomials in the first non-symmetric representation
Anokhina, A.; Mironov, A.; Morozov, A.; Morozov, And.
2014-05-01
We describe the explicit form and the hidden structure of the answer for the HOMFLY polynomial for the figure-8 and some other 3-strand knots in representation [21]. This is the first result for non-torus knots beyond (anti)symmetric representations, and its evaluation is far more complicated. We provide a whole variety of different arguments, allowing one to guess the answer for the figure-8 knot, which can be also partly used in more complicated situations. Finally we report the result of exact calculation for figure-8 and some other 3-strand knots based on the previously developed sophisticated technique of multi-strand calculations. We also discuss a formula for the superpolynomial in representation [21] for the figure-8 knot, which heavily relies on the conjectural form of superpolynomial expansion nearby the special polynomial point. Generalizations and details will be presented elsewhere.
Colored knot polynomials. HOMFLY in representation [2,1
Mironov, A; Morozov, An; Sleptsov, A
2015-01-01
This paper starts a systematic description of colored knot polynomials, beginning from the first non-(anti)symmetric representation R=[2,1]. The project involves several steps: (i) parametrization of big families of knots a la arXiv:1506.00339, (ii) evaluating Racah/mixing matrices for various numbers of strands in various representations a la arXiv:1112.2654, (iii) tabulating and collecting the results at www.knotebook.org. In this paper we discuss only representation R=[2,1] and construct all necessary ingredients that allow one to evaluate knot/links represented by three strand closed parallel braids with inserted double-fat fingers. In particular, it is used to evaluate knots from a 7-parametric family: this family contains over 80% of knots with up to 10 intersections, but does not include mutants.
Barrier formation: potential molecular mechanism of enamel fluorosis
Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; Denbesten, P.; Smith, C.E.; Bronckers, A.L.J.J.
2014-01-01
Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested
Barrier formation: potential molecular mechanism of enamel fluorosis
Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; Denbesten, P.; Smith, C.E.; Bronckers, A.L.J.J.
2014-01-01
Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested
Tooth enamel and enameloid in actinopterygian fish
I.SASAGAWA; M.ISHIYAMA; H.YOKOSUKA; M.MIKAMI; T.UCHIDA
2009-01-01
The morphological features of tooth enamel and enameloid in actinopterygian fish are reviewed to provide basic data concerning the biomineralization of teeth in lower vertebrates. Enameloid, which covers the tooth surface, is a unique well-mineralized tissue and usually has the same functions as mammalian tooth enamel. However, the development of enameloi is different from that of the enamel produced by dental epithelial cells. Enameloid is made by a combination of odontoblasts and dental epithelial cells. An organic matrix that contains collagen is provided by odontoblasts, and then dental epithelial cells dissolve the degenerate matrix and suooly inorganic ions during advanced crystal growth in enameloid. It is likely that enameloid is a good model for studying the growth of well-mineralized hard tissues in vertebrates. Some actinopterygian fish possess a collar enamel layer that is situated at the surface of the tooth shaft, indicating that the origin of tooth enamel is found in fish. Collar enamel is thought to be a precursor of mammalian enamel, although it is thin and not well mineralized in comparison with enameloid. In Lepisosteus and Polypterus, both of which are living actinopterygians,both enameloid and enamel are found in the same tooth. Therefore, they ace suitable materials for examining the developmental processes of enameloid and enamel and the relationship among them.
The evolution of dinosaur tooth enamel microstructure.
Hwang, Sunny H
2011-02-01
The evolution of tooth enamel microstructure in both extinct and extant mammalian groups has been extensively documented, but is poorly known in reptiles, including dinosaurs. Previous intensive sampling of dinosaur tooth enamel microstructure revealed that: (1) the three-dimensional arrangement of enamel types and features within a tooth-the schmelzmuster-is most useful in diagnosing dinosaur clades at or around the family level; (2) enamel microstructure complexity is correlated with tooth morphology complexity and not necessarily with phylogenetic position; and (3) there is a large amount of homoplasy within Theropoda but much less within Ornithischia. In this study, the examination of the enamel microstructure of 28 additional dinosaur taxa fills in taxonomic gaps of previous studies and reinforces the aforementioned conclusions. Additionally, these new specimens reveal that within clades such as Sauropodomorpha, Neotheropoda, and Euornithopoda, the more basal taxa have simpler enamel that is a precursor to the more complex enamel of more derived taxa and that schmelzmusters evolve in a stepwise fashion. In the particularly well-sampled clade of Euornithopoda, correlations between the evolution of dental and enamel characters could be drawn. The ancestral schmelzmuster for Genasauria remains ambiguous due to the dearth of basal ornithischian teeth available for study. These new specimens provide new insights into the evolution of tooth enamel microstructure in dinosaurs, emphasizing the importance of thorough sampling within broadly inclusive clades, especially among their more basal members.
Femtosecond laser ablation of enamel
Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui
2016-06-01
The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.
Dentin-enamel adhesives in pediatric dentistry: an update.
García-Godoy, Franklin; Donly, Kevin J
2015-01-01
Adhesives and composite technology have made composite resins and polyacid-modified resin-based composites (compomers) very popular as materials to restore primary and permanent anterior and posterior teeth. More conservative preparations can be performed that maintain more tooth structure due to the adhesive properties of the adhesives used with composites and compomers. Meticulous care in the placement of adhesives and, subsequently, resin-based composites and compomers is necessary to produce long-term satisfactory results. The purpose of this paper is to update the current status in regards to dentin-enamel adhesives in primary teeth.
In-vitro Thermal Maps to Characterize Human Dental Enamel and Dentin.
Lancaster, Paula; Brettle, David; Carmichael, Fiona; Clerehugh, Val
2017-01-01
The crown of a human tooth has an outer layer of highly-mineralized tissue called enamel, beneath which is dentin, a less-mineralized tissue which forms the bulk of the tooth-crown and root. The composition and structure of enamel and dentin are different, resulting in different thermal properties. This gives an opportunity to characterize enamel and dentin from their thermal properties and to visually present the findings as a thermal map. The thermal properties of demineralized enamel and dentin may also be sufficiently different from sound tissue to be seen on a thermal map, underpinning future thermal assessment of caries. The primary aim of this novel study was to produce a thermal map of a sound, human tooth-slice to visually characterize enamel and dentin. The secondary aim was to map a human tooth-slice with demineralized enamel and dentin to consider future diagnostic potential of thermal maps for caries-detection. Two human slices of teeth, one sound and one demineralized from a natural carious lesion, were cooled on ice, then transferred to a hotplate at 30°C where the rewarming-sequence was captured by an infra-red thermal camera. Calculation of thermal diffusivity and thermal conductivity was undertaken, and two methods of data-processing used customized software to produce thermal maps from the thermal characteristic-time-to-relaxation and heat-exchange. The two types of thermal maps characterized enamel and dentin. In addition, sound and demineralized enamel and dentin were distinguishable within both maps. This supports thermal assessment of caries and requires further investigation on a whole tooth.
Development Enamel Defects in Children Prenatally Exposed to Anti-Epileptic Drugs
Jacobsen, Pernille Endrup; Henriksen, Tine Brink; Haubek, Dorte
2013-01-01
hypoplasia were recorded. Results Children prenatally exposed to AED have an increased prevalence of enamel hypoplasia (11% vs. 4%, odds ratio (OR) = 3.6 [95% confidence interval (CI): 0.9 to 15.4]), diffuse opacities (18% vs. 7%, OR = 3.0; [95% CI: 1.0 to 8.7, p3) white opacities (18...... of developing numerous teeth with white opacities in their primary and permanent dentition. In addition, they also have an increased risk of developing diffuse opacities and enamel hypoplasia in their primary teeth....
The properties of conformal blocks, the AGT hypothesis, and knot polynomials
Morozov, A. A.
2016-09-01
Various properties of correlators of the two-dimensional conformal field theory are discussed. Specifically, their relation to the partition function of the four-dimensional supersymmetric theory is analyzed. In addition to being of interest in its own right, this relation is of practical importance. For example, it is much easier to calculate the known expressions for the partition function of supersymmetric theory than to calculate directly the expressions for correlators in conformal theory. The examined representation of conformal theory correlators as a matrix model serves the same purpose. The integral form of these correlators allows one to generalize the obtained results for the Virasoro algebra to more complicated cases of the W algebra or the quantum Virasoro algebra. This provides an opportunity to examine more complex configurations in conformal field theory. The three-dimensional Chern-Simons theory is discussed in the second part of the present review. The current interest in this theory stems largely from its relation to the mathematical knot theory (a rather well-developed area of mathematics known since the 17th century). The primary objective of this theory is to develop an algorithm that allows one to distinguish different knots (closed loops in three-dimensional space). The basic way to do this is by constructing the so-called knot invariants.
Solving Infinite Kolam in Knot Theory
Ishimoto, Yukitaka
2007-01-01
In south India, there are traditional patterns of line-drawings encircling dots, called ``Kolam'', among which one-line drawings or the ``infinite Kolam'' provide very interesting questions in mathematics. For example, we address the following simple question: how many patterns of infinite Kolam can we draw for a given grid pattern of dots? The simplest way is to draw possible patterns of Kolam while judging if it is infinite Kolam. Such a search problem seems to be NP complete. However, it is certainly not. In this paper, we focus on diamond-shaped grid patterns of dots, (1-3-5-3-1) and (1-3-5-7-5-3-1) in particular. By using the knot-theory description of the infinite Kolam, we show how to find the solution, which inevitably gives a sketch of the proof for the statement ``infinite Kolam is not NP complete.'' Its further discussion will be given in the final section.
Decay of trefoil and other magnetic knots
Candelaresi, Simon; Brandenburg, Axel
2010-01-01
Two setups with interlocked magnetic flux tubes are used to study the evolution of magnetic energy and helicity on magnetohydrodynamical (MHD) systems like plasmas. In one setup the initial helicity is zero while in the other it is finite. To see if it is the actual linking or merely the helicity content that influences the dynamics of the system we also consider a setup with unlinked field lines as well as a field configuration in the shape of a trefoil knot. For helical systems the decay of magnetic energy is slowed down by the helicity which decays slowly. It turns out that it is the helicity content, rather than the actual linking, that is significant for the dynamics.
Teaching and Learning of Knot Theory in School Mathematics
Kawauchi, Akio
2012-01-01
This book is the result of a joint venture between Professor Akio Kawauchi, Osaka City University, well-known for his research in knot theory, and the Osaka study group of mathematics education, founded by Professor Hirokazu Okamori and now chaired by his successor Professor Tomoko Yanagimoto, Osaka Kyoiku University. The seven chapters address the teaching and learning of knot theory from several perspectives. Readers will find an extremely clear and concise introduction to the fundamentals of knot theory, an overview of curricular developments in Japan, and in particular a series of teaching
Intraoperative wide bore nasogastric tube knotting: A rare incidence.
Lamba, Sangeeta; Sethi, Surendra K; Khare, Arvind; Saini, Sudheendra
2016-01-01
Nasogastric tubes are commonly used in anesthetic practice for gastric decompression in surgical patients intraoperatively. The indications for its use are associated with a number of potential complications. Knotting of small-bore nasogastric tubes is usually common both during insertion and removal as compared to wide bore nasogastric tubes. Knotting of wide bore nasogastric tube is a rare complication and if occurs usually seen in long standing cases. We hereby report a case of incidental knotting of wide bore nasogastric tube that occurred intraoperatively.
Motion of charged particles in a knotted electromagnetic field
Arrayas, M; Trueba, J L, E-mail: joseluis.trueba@urjc.e [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain)
2010-06-11
In this paper we consider the classical relativistic motion of charged particles in a knotted electromagnetic field. After reviewing how to construct electromagnetic knots from maps between the three-sphere and the two-sphere, we introduce a mean quadratic radius of the energy density distribution in order to study some properties of this field. We study the classical relativistic motion of electrons in the electromagnetic field of the Hopf map, and compute their trajectories. It is observed that these electrons initially at rest are strongly accelerated by the electromagnetic force, becoming ultrarelativistic in a period of time that depends on the knot energy and size.
Pinus pinaster Knot: A Source of Polyphenols against Plasmopara viticola.
Gabaston, Julien; Richard, Tristan; Cluzet, Stéphanie; Palos Pinto, Antonio; Dufour, Marie-Cécile; Corio-Costet, Marie-France; Mérillon, Jean-Michel
2017-09-29
Pine knot extract from Pinus pinaster byproducts was characterized by UHPLC-DAD-MS and NMR. Fourteen polyphenols divided into four classes were identified as follows: lignans (nortrachelogenin, pinoresinol, matairesinol, isolariciresinol, secoisolariciresinol), flavonoids (pinocembrin, pinobanksin, dihydrokaempferol, taxifolin), stilbenes (pinosylvin, pinosylvin monomethyl ether, pterostilbene), and phenolic acids (caffeic acid, ferulic acid). The antifungal potential of pine knot extract, as well as the main compounds, was tested in vitro against Plasmopara viticola. The ethanolic extract showed a strong antimildew activity. In addition, pinosylvins and pinocembrin demonstrated significant inhibition of zoospore mobility and mildew development. These findings strongly suggest that pine knot is a potential biomass that could be used as a natural antifungal product.
Topological Structure of Knotted Vortex Lines in Liquid Crystals
DUAN Yi-Shi; ZHAO Li; ZHANG Xin-Hui
2007-01-01
In this paper, a novel decomposition expression for the U(1) gauge field in liquid crystals (LCs) is derived.Using this decomposition expression and the φ-mapping topological current theory,.we investigate the topological structure of the vortex lines in LCs in detail. A topological invariant, i.e., the Chern-Simons (CS) action for the knotted vortex lines is presented, and the CS action is shown to be the total sum of all the self-linking and linking numbers of the knot family. Moreover, it is pointed out that the CS action is preserved in the branch processes of the knotted vortex lines.
Enamel Regeneration - Current Progress and Challenges
Baswaraj; H.K, Navin; K.B, Prasanna
2014-01-01
Dental Enamel is the outermost covering of teeth. It is hardest mineralized tissue present in the human body. Enamel faces the challenge of maintaining its integrity in a constant demineralization and remineralization within the oral environment and it is vulnerable to wear, damage, and decay. It cannot regenerate itself, because it is formed by a layer of cells that are lost after the tooth eruption. Conventional treatment relies on synthetic materials to restore lost enamel that cannot mimic natural enamel. With advances in material science and understanding of basic principles of organic matrix mediated mineralization paves a way for formation of synthetic enamel. The knowledge of enamel formation and understanding of protein interactions and their gene products function along with the isolation of postnatal stem cells from various sources in the oral cavity, and the development of smart materials for cell and growth factor delivery, makes possibility for biological based enamel regeneration. This article will review the recent endeavor on biomimetic synthesis and cell based strategies for enamel regeneration. PMID:25386548
FLUORESCENCE IN DISSOLVED FRACTIONS OF HUMAN ENAMEL
HAFSTROMBJORKMAN, U; SUNDSTROM, F; TENBOSCH, JJ
Fluorescence induced by laser light is useful in early detection of enamel caries. The present work studied the fluorescence emission pattern in dissolved human enamel and in different molecular weight fractions obtained after gel chromatography or dialysis followed by ultrafiltration. For
Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study
CHARONE, Senda; PORTELA, Maristela Barbosa; MARTINS, Karol de Oliveira; SOARES, Rosangela Maria; CASTRO, Gloria Fernanda
2017-01-01
Abstract Objectives This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+) children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH), Polarized Light Microscopy (PLM) and the quantity of calcium ions (Ca2+) released from the enamel. Material and Methods Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140) enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1); mixed biofilm formed by C. albicans and C. tropicalis (Group 2); mixed biofilm formed by C. albicans and C. parapsilosis (Group 3); mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4); biofilm formed by C. albicans ATCC (Group 5) and medium without Candida (Group 6). Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca2+ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%. Results TMH showed a gradual reduction in enamel hardness (p<0.05) from the 1st to 15th day, but mainly five days after biofilm formation in all groups. The PLM showed superficial lesions indicating an increase in porosity. C. albicans caused the release of Ca2+ into suspension during biofilm formation. Conclusion Candida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro. PMID:28198976
Role of Candida species from HIV infected children in enamel caries lesions: an in vitro study
Senda CHARONE
Full Text Available Abstract Objectives This study analyzed the capacity of Candida spp. from dental biofilm of HIV infected (HIV+ children to demineralize primary molar enamel in vitro by Transversal Microhardness (TMH, Polarized Light Microscopy (PLM and the quantity of calcium ions (Ca2+ released from the enamel. Material and Methods Candida spp. samples were isolated from the supragingival biofilm of HIV+ children. A hundred and forty (140 enamel blocks were randomly assigned to six groups: biofilm formed by C. albicans (Group 1; mixed biofilm formed by C. albicans and C. tropicalis (Group 2; mixed biofilm formed by C. albicans and C. parapsilosis (Group 3; mixed biofilm formed by C. albicans, C. parapsilosis and C. glabrata (Group 4; biofilm formed by C. albicans ATCC (Group 5 and medium without Candida (Group 6. Enamel blocks from each group were removed on days 3, 5, 8 and 15 after biofilm formation to evaluate the TMH and images of enamel were analyzed by PLM. The quantity of Ca2+ released, from Groups 1 and 6, was determined using an Atomic Absorption Spectrophotometer. The SPSS program was used for statistical analysis and the significance level was 5%. Results TMH showed a gradual reduction in enamel hardness (p<0.05 from the 1st to 15th day, but mainly five days after biofilm formation in all groups. The PLM showed superficial lesions indicating an increase in porosity. C. albicans caused the release of Ca2+ into suspension during biofilm formation. Conclusion Candida species from dental biofilm of HIV+ children can cause demineralization of primary enamel in vitro.
Knots, splices and rope-work an illustrated handbook
Verrill, A Hyatt
2006-01-01
This treasury of practical and ornamental knots ranges from easy half-hitches and bow-lines to intricate rope-work projects, such as rope buckles and cask slings. Detailed instructions accompany the 148 drawings.
Linked and knotted chimera filaments in oscillatory systems.
Lau, Hon Wai; Davidsen, Jörn
2016-07-01
While the existence of stable knotted and linked vortex lines has been established in many experimental and theoretical systems, their existence in oscillatory systems and systems with nonlocal coupling has remained elusive. Here, we present strong numerical evidence that stable knots and links such as trefoils and Hopf links do exist in simple, complex, and chaotic oscillatory systems if the coupling between the oscillators is neither too short ranged nor too long ranged. In this case, effective repulsive forces between vortex lines in knotted and linked structures stabilize curvature-driven shrinkage observed for single vortex rings. In contrast to real fluids and excitable media, the vortex lines correspond to scroll wave chimeras [synchronized scroll waves with spatially extended (tubelike) unsynchronized filaments], a prime example of spontaneous synchrony breaking in systems of identical oscillators. In the case of complex oscillatory systems, this leads to a topological superstructure combining knotted filaments and synchronization defect sheets.
Topological Aspect of Knotted Vortex Filaments in Excitable Media
REN Ji-Rong; ZHU Tao; DUAN Yi-Shi
2008-01-01
Scroll waves exist ubiquitously in three-dimensional excitable media.The rotation centre can be regarded as a topological object called the vortex filament.In three-dimensional space,the vortex filaments usually form closed loops,and can be even linked and knotted.We give a rigorous topological description of knotted vortex filaments.By using the Φ-mapping topological current theory,we rewrite the topological current form of the charge density of vortex filaments,and using this topological current we reveal that the Hopf invariant of vortex filaments is just the sum of the linking and self-linking numbers of the knotted vortex filaments.We think that the precise expression of the Hopf invariant may imply a new topological constraint on knotted vortex filaments.
Tilton, Buck
2008-01-01
Untie the mystery of knot-making with this clever and handy guide. This new compendium presents all the knots you need to know, with brightly colored photographs enabling you to easily follow the instructions. In addition, the book includes copious information on using knots in most popular activities. With its clear step-by-step instructions and friendly tone, this is the one volume you can count on to guide you toward quick success in knot-making.
The beauty of knots at the molecular level.
Sauvage, Jean-Pierre; Amabilino, David B
2012-01-01
What makes a given object look beautiful to the observer, be it in the macroscopic world or at the molecular level? This very general question will be briefly addressed at the beginning of this essay, in relation to contemporary molecular chemistry and biology, leading to the general statement that, most of the time, beauty is tightly connected to function as well as to the cultural background of the observer. The main topic of the present article will be that of topologically non-trivial molecules or molecular ensembles and the fascination that such species have exerted on molecular or solid state chemists. Molecules with a graph identical to Kuratowski's K₅ or K₃,₃ graphs are indeed highly attractive from an aesthetical viewpoint, but perhaps even more fascinating and beautiful are molecular knots. A general discussion will be devoted to these compounds, which are still considered as exotic species because of the very limited number of efficient synthetic strategies leading to their preparation. Particularly efficient are templated approaches based either on transition metals such as copper(I) or on organic groups able to form hydrogen bonds or acceptor-donor stacks. A particularly noteworthy property of knots, and in particular of the trefoil knot, is their topological chirality. The isolation of both enantiomers of the trefoil knot (3₁) could be achieved and showed that such species have fascinating chiroptical properties. Finally, various routes to more complex and beautiful knots than the trefoil knot, which is the simplest non-trivial knot, will be discussed in line with the remarkable ability of transition metals to gather and orient in a very precise fashion several organic components in their coordination spheres, thus leading to synthetic precursors displaying geometries which are perfectly well adapted to the preparation of the desired knots or links.
Chern-Simons Invariants of Torus Knots and Links
Stevan, Sébastien
2010-01-01
We compute the vacuum expectation values of torus knot operators in Chern-Simons theory, and we obtain explicit formulae for all classical gauge groups and for arbitrary representations. We reproduce a known formula for the HOMFLY invariants of torus links and we obtain an analogous formula for Kauffman invariants. We also derive a formula for cable knots. We use our results to test a recently proposed conjecture that relates HOMFLY and Kauffman invariants.
SOME APPLICATIONS OF PLANAR GRAPH IN KNOT THEORY
Cheng Zhiyun; Gao Hongzhu
2012-01-01
The relationship between a link diagram and its corresponding planar graph is briefly reviewed.A necessary and sufficient condition is given to detect when a planar graph corresponds to a knot.The relationship between planar graph and almost planar Seifert surface is discussed.Using planar graph,we construct an alternating amphicheiral prime knot with crossing number n for any even number n ≥ 4.This gives an affirmative answer to problem 1.66(B) on Kirby's problem list.
Exact computation of the n-loop invariants of knots
Garoufalidis, Stavros; Scott, Shane
2015-01-01
The loop invariants of Dimofte-Garoufalidis is a formal power series with arithmetically interesting coefficients that conjecturally appears in the asymptotics of the Kashaev invariant of a knot to all orders in $1/N$. We develop methods implemented in SnapPy that compute the first 6 coefficients of the formal power series of a knot. We give examples that illustrate our method and its results.
Many-knot spline technique for approximation of data
齐东旭; 李华山
1999-01-01
A class of new fundamental functions with compact support called many-knot spline is introduced. The two-scale relation for the fundamental functions is investigated, and the higher order accuracy spline approximation scheme is constructed by using the available degrees of freedom which come from additional knots. The technique has been efficiently applied to the problems such as time-frequency analysis, computer aided geometric design, and digital signal processing.
Shunt insufficiency due to knot formation in the peritoneal catheter.
Fekete, Gábor; Nagy, Andrea; Pataki, István; Bognar, László; Novák, László
2013-07-30
The authors report a rare case of the peripheral obstruction of a ventriculoperitoneal shunt. Premature baby was operated on hydrocephalus due to germinal matrix bleeding. After two months of implantation of venticuloperitoneal shunt peripheral insufficiency of the system was emerged. During the shunt revision extensive knot formation became visible. We simply cut the catheter above the knot and the working shunt was replaced into the abdominal cavity. The postoperative course was uneventful and the baby was free of complaints for more than one year. The pathomechanism of knot formation is not clear thus the discovery of the problem during the operation is an unexpected event. In our opinion tight knot cannot be spontaneously formed intraabdominally. Loose knots can be developed and can reduce the capacity of liquor flow. We think that the knot tightens during pulling out. Longer peritoneal catheters can precipitate multiple looping and/or axial torquations and increase the peripheral resistance of the shunt. In such cases when the pulling out is challenged conversion to laparotomy is suggested.
Knots in the Helix Nebula found in H2
Matsuura, M; McHunu, B M; Tanaka, I; Wright, N J; Smith, M D; Zijlstra, A A; Viti, S; Wesson, R
2009-01-01
We present a deep and wide field-of-view (4'x 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 micron H2 v=1-0 S(1) line. The excellent seeing (0.4'') at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2.2'-6.4' from the central star (CS). At the inner edge and in the inner ring (up to 4.5' fromthe CS), the knot often show a `tadpole' shape, an elliptical head with a bright crescent inside and a long tail opposite to the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multi-peaks within a tail. In the outer ring (4.5'-6.4' from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H2 surface brightness in the inner ring: H2 exists only within the knots. Possible mechanisms which...
Regulation of dental enamel shape and hardness.
Simmer, J P; Papagerakis, P; Smith, C E; Fisher, D C; Rountrey, A N; Zheng, L; Hu, J C C
2010-10-01
Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be deposited. Starting with the onset of amelogenesis beneath the future cusp tips, the shape of the enamel layer covering the crown is determined by five growth parameters: the (1) appositional growth rate, (2) duration of appositional growth (at the cusp tip), (3) ameloblast extension rate, (4) duration of ameloblast extension, and (5) spreading rate of appositional termination. Appositional growth occurs at a mineralization front along the ameloblast distal membrane in which amorphous calcium phosphate (ACP) ribbons form and lengthen. The ACP ribbons convert into hydroxyapatite crystallites as the ribbons elongate. Appositional growth involves a secretory cycle that is reflected in a series of incremental lines. A potentially important function of enamel proteins is to ensure alignment of successive mineral increments on the tips of enamel ribbons deposited in the previous cycle, causing the crystallites to lengthen with each cycle. Enamel hardens in a maturation process that involves mineral deposition onto the sides of existing crystallites until they interlock with adjacent crystallites. Neutralization of acidity generated by hydroxyapatite formation is a key part of the mechanism. Here we review the growth parameters that determine the shape of the enamel crown as well as the mechanisms of enamel appositional growth and maturation.
Enamel wear opposing polished and aged zirconia.
Burgess, J O; Janyavula, S; Lawson, N C; Lucas, T J; Cakir, D
2014-01-01
Aging of dental zirconia roughens its surface through low temperature degradation. We hypothesized that age-related roughening of zirconia crowns may cause detrimental wear to the enamel of an opposing tooth. To test our hypothesis, we subjected artificially aged zirconia and reference specimens to simulated mastication in a wear device and measured the wear of an opposing enamel cusp. Additionally, the roughness of the pretest surfaces was measured. The zirconia specimens, artificially aged by autoclave, showed no significant increase in roughness compared to the nonaged specimens. Furthermore, no significant difference in material or opposing enamel wear between the aged and nonaged zirconia was seen. All zirconia specimens showed less material and opposing enamel wear than the enamel to enamel control or veneering porcelain specimens. Scanning electron micrographs showed relatively smooth surfaces of aged and nonaged zirconia following wear testing. The micrographs of the veneering ceramic showed sharp fractured edges and fragments of wear debris. Zirconia may be considered a wear-friendly material for restorations opposing enamel, even after simulated aging.
Regulation of Dental Enamel Shape and Hardness
Simmer, J.P.; Papagerakis, P.; Smith, C.E.; Fisher, D.C.; Rountrey, A.N.; Zheng, L.; Hu, J.C.-C.
2010-01-01
Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be deposited. Starting with the onset of amelogenesis beneath the future cusp tips, the shape of the enamel layer covering the crown is determined by five growth parameters: the (1) appositional growth rate, (2) duration of appositional growth (at the cusp tip), (3) ameloblast extension rate, (4) duration of ameloblast extension, and (5) spreading rate of appositional termination. Appositional growth occurs at a mineralization front along the ameloblast distal membrane in which amorphous calcium phosphate (ACP) ribbons form and lengthen. The ACP ribbons convert into hydroxyapatite crystallites as the ribbons elongate. Appositional growth involves a secretory cycle that is reflected in a series of incremental lines. A potentially important function of enamel proteins is to ensure alignment of successive mineral increments on the tips of enamel ribbons deposited in the previous cycle, causing the crystallites to lengthen with each cycle. Enamel hardens in a maturation process that involves mineral deposition onto the sides of existing crystallites until they interlock with adjacent crystallites. Neutralization of acidity generated by hydroxyapatite formation is a key part of the mechanism. Here we review the growth parameters that determine the shape of the enamel crown as well as the mechanisms of enamel appositional growth and maturation. PMID:20675598
Eloy Caballo-Ponce
2017-06-01
Full Text Available The study of the molecular basis of tree diseases is lately receiving a renewed attention, especially with the emerging perception that pathogens require specific pathogenicity and virulence factors to successfully colonize woody hosts. Pathosystems involving woody plants are notoriously difficult to study, although the use of model bacterial strains together with genetically homogeneous micropropagated plant material is providing a significant impetus to our understanding of the molecular determinants leading to disease. The gammaproteobacterium Pseudomonas savastanoi belongs to the intensively studied Pseudomonas syringae complex, and includes three pathogenic lineages causing tumorous overgrowths (knots in diverse economically relevant trees and shrubs. As it occurs with many other bacteria, pathogenicity of P. savastanoi is dependent on a type III secretion system, which is accompanied by a core set of at least 20 effector genes shared among strains isolated from olive, oleander, and ash. The induction of knots of wild-type size requires that the pathogen maintains adequate levels of diverse metabolites, including the phytohormones indole-3-acetic acid and cytokinins, as well as cyclic-di-GMP, some of which can also regulate the expression of other pathogenicity and virulence genes and participate in bacterial competitiveness. In a remarkable example of social networking, quorum sensing molecules allow for the communication among P. savastanoi and other members of the knot microbiome, while at the same time are essential for tumor formation. Additionally, a distinguishing feature of bacteria from the P. syringae complex isolated from woody organs is the possession of a 15 kb genomic island (WHOP carrying four operons and three other genes involved in degradation of phenolic compounds. Two of these operons mediate the catabolism of anthranilate and catechol and, together with another operon, are required for the induction of full-size tumors
Saeed Najafi
2016-09-01
Full Text Available Knots appear frequently in semiflexible (biopolymers, including double-stranded DNA, and their presence can affect the polymer’s physical and functional properties. In particular, it is possible and indeed often the case that multiple knots appear on a single chain, with effects which have only come under scrutiny in the last few years. In this manuscript, we study the interaction of two knots on a stretched semiflexible polymer, expanding some recent results on the topic. Specifically, we consider an idealization of a typical optical tweezers experiment and show how the bending rigidity of the chain—And consequently its persistence length—Influences the distribution of the entanglements; possibly more importantly, we observe and report how the relative chirality of the otherwise identical knots substantially modifies their interaction. We analyze the free energy of the chain and extract the effective interactions between embedded knots, rationalizing some of their pertinent features by means of simple effective models. We believe the salient aspect of the knot–knot interactions emerging from our study will be present in a large number of semiflexible polymers under tension, with important consequences for the characterization and manipulation of these systems—Be they artificial or biologica in origin—And for their technological application.
Weaker dental enamel explains dental decay.
Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong
2015-01-01
Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.
MMP20 Promotes a Smooth Enamel Surface, a Strong DEJ, and a Decussating Enamel Rod Pattern
Bartlett, John D.; Skobe, Ziedonis; Nanci, Antonio; Smith, Charles E.
2012-01-01
Mutations of the Matrix metalloproteinase-20 (MMP20, enamelysin) gene cause autosomal recessive amelogenesis imperfecta and Mmp20 ablated mice also have malformed dental enamel. Here we show that Mmp20 null mouse secretory stage ameloblasts maintained a columnar shape and were present as a single layer of cells. However, the null maturation stage ameloblasts covered extraneous nodules of ectopic calcified material formed at the enamel surface. Remarkably, nodule formation occurs in null mouse enamel when MMP20 is normally no longer expressed. The malformed enamel in Mmp20 null teeth was loosely attached to the dentin and the entire enamel layer tended to separate from the dentin indicative of a faulty DEJ. The enamel rod pattern was also altered in Mmp20 null mice. Each enamel rod is formed by a single ameloblast and is a mineralized record of the migration path of the ameloblast that formed it. The Mmp20 null mouse enamel rods were grossly malformed or were absent indicating that the ameloblasts do not migrate properly when backing away from the DEJ. Thus, MMP20 is required for ameloblast cell movement necessary to form the decussating enamel rod patterns, for the prevention of ectopic mineral formation, and to maintain a functional DEJ. PMID:22243247
Optical knots and contact geometry II. From Hopf links to transverse and cosmetic knots
Kholodenko, Arkady L
2014-01-01
In 1985 Moffatt conjectured that in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. Using methods of contact geometry Etnyre and Ghrist in 2000 developed the existence-type proof of the Moffatt conjecture. The alternative proof, also of existence-type, was proposed by Enciso and Peralta -Salas in 2012. In all three papers the Beltrami equation was used as point of departure. However, only work by Etnyre and Ghrist takes full advantage of contact-geometric nature of the Beltrami equation. In this work we propose the constructive proof of the Moffatt conjecture based on ideas and methods of contact geometry. We discuss in sufficient detail various physical processes generating such knotted structures. By employing the correspondence between ideal hydrodynamics and electrodynamics discussed in part I, the Moffatt conjecture is proved for Maxwellian electrodynamics. The potential relevance of the obtained results for source-free Yang-Mills and gravity fields is also br...
Caries prevalence and enamel defects in 5- and 10-year-old children with cleft lip and/or palate
Sundell, Anna Lena; Nilsson, Anna-Karin; Ullbro, Christer
2016-01-01
OBJECTIVE: To determine the prevalence of dental caries and enamel defects in 5- and 10-year-old Swedish children with cleft lip and/or palate (CL(P)) in comparison to non-cleft controls. MATERIALS AND METHODS: The study group consisted of 139 children with CL(P) (80 subjects aged 5 years and 59...... aged 10 years) and 313 age-matched non-cleft controls. All children were examined by one of two calibrated examiners. Caries was scored according to the International Caries Detection and Assessment System (ICDAS-II) and enamel defects as presence and frequency of hypoplasia and hypomineralization...... prevalence of enamel defects was found in CL(P) children of both age groups and anterior permanent teeth were most commonly affected. CONCLUSIONS: Preschool children with cleft lip and/or palate seem to have more caries in the primary dentition than age-matched non-cleft controls. Enamel defects were more...
Dental enamel, fluorosis and amoxicillin
I. Ciarrocchi
2012-06-01
Full Text Available Introduction: Amoxicillin is one of the most used antibiotics among pediatric patients for the treatment of upper respiratory tract infections and specially for acute otitis media (AOM, a common diseases of infants and childhood. It has been speculated that the use of amoxicillin during early childhood could be associated with dental enamel fluorosis, also described in literature with the term Molar Incisor Hypomineralization (MIH, because they are generally situated in one or more 1st permanent molars and less frequently in the incisors. The effect of Amoxicillin seems to be independent of other risk factors such as fluoride intake, prematurity, hypoxia, hypocalcaemia, exposure to dioxins, chikenpox, otitis media, high fever and could have a significant impact on oral health for the wide use of this drug in that period of life. Objective: The aim of this work was to review the current literature about the association between amoxicillin and fluorosis. Methods and Results: A literature survey was done by applying the Medline database (Entrez PubMed; the Cochrane Library database of the Cochrane Collaboration (CENTRAL. The databases were searched using the following strategy and keywords: amoxicillin* AND (dental fluorosis* OR dental enamel* AND MIH*. After selecting the studies, only three relevant articles published between 1966 and 2011 were included in the review. Conclusion: The presence of several methodological issues does not allow to draw any evidence-based conclusions. No evidence of association was detected, therefore, there is a need of further well-designed studies to assess the scientific evidence of the relationship between amoxicillin and fluorosis and to restrict the prescription of this drug for recurrent upper respiratory tract infections especially acute otitis media (AOM during the first two years of life. When it is possible can be opportune to use an alternative antibiotic treatment.
Materials science: Lessons from tooth enamel
Espinosa, Horacio D.; Soler-Crespo, Rafael
2017-03-01
A remarkable composite material has been made that mimics the structure of tooth enamel. This achievement opens up the exploration of new composite materials and of computational methods that reliably predict their properties. See Letter p.95
Dental Enamel Defects and Celiac Disease
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Oral aspects in celiac disease children: clinical and dental enamel chemical evaluation.
de Carvalho, Fabrício Kitazono; de Queiroz, Alexandra Mussolino; Bezerra da Silva, Raquel Assed; Sawamura, Regina; Bachmann, Luciano; Bezerra da Silva, Léa Assed; Nelson-Filho, Paulo
2015-06-01
The aim of this study was to evaluate the oral manifestations of celiac disease (CD), the chemical composition of dental enamel, and the occurrence of CD in children with dental enamel defects (DEDs). In the study, 52 children with CD and 52 controls were examined for DEDs, recurrent aphthous stomatitis (RAS), dental caries experience, and salivary parameters. In addition, 10 exfoliated primary enamel molars from each group were analyzed by energy dispersive x-ray spectroscopy and Fourier transform infrared spectroscopy. Fifty children with DEDs were submitted to CD diagnosis. Among the children with CD, a higher prevalence of DEDs (P = .00001) and RAS (P = .0052), lower caries experience (P = .0024), and reduction of salivary flow (P = .0060) were observed. Dental enamel from the children with CD demonstrated a lower calcium-to-phosphorus ratio (P = .0136), but no difference in the carbonate-to-phosphate ratio (P = .5862) was observed. In the multivariate analysis, CD was a protective factor for caries (OR = 0.74) and a risk factor for RAS (OR3.23). The children with CD presented with more RAS, DEDs, reduction of salivary flow, and chemical alterations in the enamel. Copyright © 2015 Elsevier Inc. All rights reserved.
Aesthetic approach for anterior teeth with enamel hypoplasia
Josué Martos
2012-01-01
Full Text Available Enamel hypoplasia is a developmental defect of the enamel that is produced by a disturbance in the formation of the organic enamel matrix, clinically visible as enamel defects. Disorders that occur during the stages of enamel development and maturation reduce the amount or thickness of the enamel, resulting in white spots, tiny grooves, depressions and fissures in the enamel surface. The complexity and intensity of the dental deformity lesions will conduct the ideal treatment-associating conservative techniques. This article presents a case report of a restorative treatment of enamel hypoplasia using hybrid composite resin to mask color alteration and enamel defects. An aesthetic appearance that respects the tooth polychromatic and the self-esteem of the patient can be achieved with this approach.
Colored HOMFLY polynomials of knots presented as double fat diagrams
Mironov, A; Morozov, An; Ramadevi, P; Singh, Vivek Kumar
2015-01-01
Many knots and links in S^3 can be drawn as gluing of three manifolds with one or more four-punctured S^2 boundaries. We call these knot diagrams as double fat graphs whose invariants involve only the knowledge of the fusion and the braiding matrices of four-strand braids. Incorporating the properties of four-point conformal blocks in WZNW models, we conjecture colored HOMFLY polynomials for these double fat graphs where the color can be rectangular or non-rectangular representation. With the recent work of Gu-Jockers, the fusion matrices for the non-rectangular [21] representation, the first which involves multiplicity is known. We verify our conjecture by comparing with the [21] colored HOMFLY of many knots, obtained as closure of three braids. The conjectured form is computationally very effective leading to writing [21]-colored HOMFLY polynomials for many pretzel type knots and non-pretzel type knots. In particular, we find class of pretzel mutants which are distinguished and another class of mutants whic...
Knot Invariants from Topological Recursion on Augmentation Varieties
Gu, Jie; Klemm, Albrecht; Soroush, Masoud
2014-01-01
Using the duality between Wilson loop expectation values of SU(N) Chern-Simons theory on $S^3$ and topological open-string amplitudes on the local mirror of the resolved conifold, we study knots on $S^3$ and their invariants encoded in colored HOMFLY polynomials by means of topological recursion. In the context of the local mirror Calabi-Yau threefold of the resolved conifold, we generalize the topological recursion of the remodelled B-model in order to study branes beyond the class of toric Harvey-Lawson special Lagrangians -- as required for analyzing non-trivial knots on $S^3$. The basic ingredients for the proposed recursion are the spectral curve, given by the augmentation variety of the knot, and the calibrated annulus kernel, encoding the topological annulus amplitudes associated to the knot. We present an explicit construction of the calibrated annulus kernel for torus knots and demonstrate the validity of the topological recursion. We further argue that -- if an explicit form of the calibrated annulu...
Decay of helical and non-helical magnetic knots
Candelaresi, Simon
2011-01-01
We present calculations of the relaxation of magnetic field structures that have the shape of particular knots and links. A set of helical magnetic flux configurations is considered, which we call $n$-foil knots of which the trefoil knot is the most primitive member. We also consider two non-helical knots, namely the Borromean rings as well as a single interlocked flux rope that also serves as the logo of the Inter-University Centre for Astronomy and Astrophysics in Pune, India. The field decay characteristics of both configurations is investigated and compared with previous calculations of helical and non-helical triple ring configurations. For the $n$-foil knots the decay is described by power laws that range form $t^{-2/3}$ to $t^{-1/3}$, which can be as slow as the $t^{-1/3}$ behavior for helical triple-ring structures that was seen in earlier work. The two non-helical configurations decay like $t^{-1}$, which is somewhat slower than the previously obtained $t^{-3/2}$ behavior in the decay of interlocked ...
Enamel hypomineralization due to endocrine disruptors.
Jedeon, Katia; Marciano, Clémence; Loiodice, Sophia; Boudalia, Sofiane; Canivenc Lavier, Marie-Chantal; Berdal, Ariane; Babajko, Sylvie
2014-08-01
There has been increasing concerns over last 20 years about the potential adverse effects of endocrine disruptors (EDs). Bisphenol A (BPA), genistein (G) and vinclozolin (V) are three widely used EDs having similar effects. Tooth enamel has recently been found to be an additional target of BPA that may be a causal agent of molar incisor hypomineralization (MIH). However, populations are exposed to many diverse EDs simultaneously. The purpose of this study was therefore to assess the effects of the combination of G, V and BPA on tooth enamel. Rats were exposed daily in utero and after birth to low doses of EDs mimicking human exposure during the critical fetal and suckling periods when amelogenesis takes place. The proportion of rats presenting opaque areas of enamel hypomineralization was higher when rats were treated with BPA alone than with a combination of EDs. The levels of mRNAs encoding the main enamel proteins varied with BPA treatment alone and did not differ significantly between controls and combined treatment groups. In vitro, rat ameloblastic HAT-7 cells were treated with the three EDs. BPA induced enamelin and reduced klk4 expression, G had no such effects and V reduced enamelin expression. These findings suggest that combinations of EDs may affect enamel less severely than BPA alone, and indicate that enamel hypomineralization may differ according to the characteristics of the ED exposure.
Millett, Kenneth C; Rawdon, Eric J; Stasiak, Andrzej; Physical and Numerical Models in Knot theory: including Applications to the Life Sciences; Conference on Knots, Random Walks and Biomolecules
2005-01-01
The physical properties of knotted and linked configurations in space have long been of interest to mathematicians. More recently, these properties have become significant to biologists, physicists, and engineers among others. Their depth of importance and breadth of application are now widely appreciated and valuable progress continues to be made each year. This volume presents several contributions from researchers using computers to study problems that would otherwise be intractable. While computations have long been used to analyze problems, formulate conjectures, and search for special structures in knot theory, increased computational power has made them a staple in many facets of the field. The volume also includes contributions concentrating on models researchers use to understand knotting, linking, and entanglement in physical and biological systems. Topics include properties of knot invariants, knot tabulation, studies of hyperbolic structures, knot energies, the exploration of spaces of knots, knot...
Ham, J.-Y.; Lee, J.
2016-09-01
We calculate the Chern-Simons invariants of twist-knot orbifolds using the Schläfli formula for the generalized Chern-Simons function on the family of twist knot cone-manifold structures. Following the general instruction of Hilden, Lozano, and Montesinos-Amilibia, we here present concrete formulae and calculations. We use the Pythagorean Theorem, which was used by Ham, Mednykh and Petrov, to relate the complex length of the longitude and the complex distance between the two axes fixed by two generators. As an application, we calculate the Chern-Simons invariants of cyclic coverings of the hyperbolic twist-knot orbifolds. We also derive some interesting results. The explicit formulae of the A-polynomials of twist knots are obtained from the complex distance polynomials. Hence the edge polynomials corresponding to the edges of the Newton polygons of the A-polynomials of twist knots can be obtained. In particular, the number of boundary components of every incompressible surface corresponding to slope -4n+2 turns out to be 2. Bibliography: 39 titles.
Differential expansion and rectangular HOMFLY for the figure eight knot
A. Morozov
2016-10-01
Full Text Available Differential expansion (DE for a Wilson loop average in representation R is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of 3d Chern–Simons theory. Especially simple is the relation between the DE for the trefoil 31 and for the figure eight knot 41. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso–Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfill this program for all rectangular representation R=[rs], i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.
Untangling knots via reaction-diffusion dynamics of vortex strings
Maucher, Fabian
2016-01-01
We introduce and illustrate a new approach to the unknotting problem via the dynamics of vortex strings in a nonlinear partial differential equation of reaction-diffusion type. To untangle a given knot, a Biot-Savart construction is used to initialize the knot as a vortex string in the FitzHugh-Nagumo equation. Remarkably, we find that the subsequent evolution preserves the topology of the knot and can untangle an unknot into a circle. Illustrative test case examples are presented, including the untangling of a hard unknot known as the culprit. Our approach to the unknotting problem has two novel features, in that it applies field theory rather than particle mechanics and uses reaction-diffusion dynamics in place of energy minimization.
Differential expansion and rectangular HOMFLY for the figure eight knot
Morozov, A
2016-01-01
Differential expansion (DE) for a Wilson loop average in representation $R$ is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of $3d$ Chern-Simons theory. Especially simple is the relation between the DE for the trefoil $3_1$ and for the figure eight knot $4_1$. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso-Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfil this program for all rectangular representation $R=[r^s]$, i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.
Differential expansion and rectangular HOMFLY for the figure eight knot
Morozov, A.
2016-10-01
Differential expansion (DE) for a Wilson loop average in representation R is built to respect degenerations of representations for small groups. At the same time it behaves nicely under some changes of the loop, e.g. of some knots in the case of 3d Chern-Simons theory. Especially simple is the relation between the DE for the trefoil 31 and for the figure eight knot 41. Since arbitrary colored HOMFLY for the trefoil are known from the Rosso-Jones formula, it is therefore enough to find their DE in order to make a conjecture for the figure eight. We fulfill this program for all rectangular representation R = [rs ], i.e. make a plausible conjecture for the rectangularly colored HOMFLY of the figure eight knot, which generalizes the old result for totally symmetric and antisymmetric representations.
Emission knots and polarization swings of swinging jets
Lyutikov, Maxim
2016-01-01
Knots (emission features in jets of active galactic nuclei) often show non-ballistic dynamics and variable emission/polarization properties. We model these features as emission pattern propagating in a jet that carries helical magnetic field and is launched along a changing direction. The model can reproduce a wide range of phenomena observed in the motion of knots: non-ballistic motion (both smooth and occasional sudden change of direction, and/or oscillatory behavior), variable brightness, confinement of knots' motion within an overlaying envelope. The model also reproduces smooth large polarization angle swings, and at the same time allows for the seemingly random behavior of synchrotron fluxes, polarization fraction and occasional $\\pi/2$ polarization jumps.
Untangling Knots Via Reaction-Diffusion Dynamics of Vortex Strings
Maucher, Fabian; Sutcliffe, Paul
2016-04-01
We introduce and illustrate a new approach to the unknotting problem via the dynamics of vortex strings in a nonlinear partial differential equation of reaction-diffusion type. To untangle a given knot, a Biot-Savart construction is used to initialize the knot as a vortex string in the FitzHugh-Nagumo equation. Remarkably, we find that the subsequent evolution preserves the topology of the knot and can untangle an unknot into a circle. Illustrative test case examples are presented, including the untangling of a hard unknot known as the culprit. Our approach to the unknotting problem has two novel features, in that it applies field theory rather than particle mechanics and uses reaction-diffusion dynamics in place of energy minimization.
Classification of knotted tori in 2-metastable dimension
Cencelj, Matija
2012-11-30
This paper is devoted to the classical Knotting Problem: for a given manifold N and number m describe the set of isotopy classes of embeddings N → Sm. We study the specific case of knotted tori, that is, the embeddings Sp × Sq → Sm. The classification of knotted tori up to isotopy in the metastable dimension range m > p + 3 2 q + 2, p 6 q, was given by Haefliger, Zeeman and A. Skopenkov. We consider the dimensions below the metastable range and give an explicit criterion for the finiteness of this set of isotopy classes in the 2-metastable dimension: Theorem. Assume that p+ 4 3 q +2 < mp+ 3 2 q +2 and m > 2p+q +2. Then the set of isotopy classes of smooth embeddings Sp × Sq → Sm is infinite if and only if either q + 1 or p + q + 1 is divisible by 4. © 2012 RAS(DoM) and LMS.
Knots and physics: Old wine in new bottles
Hirshfeld, Allen C.
1998-12-01
The history of the interplay between physics and mathematics in the theory of knots is briefly reviewed. In particular, Gauss' original definition of the linking number in the context of electromagnetism is presented, along with analytical, algebraical, and geometrical derivations. In a modern context, the linking number appears in the first-order term in the perturbation expansion of a Wilson loop in Chern-Simons quantum field theory. New knot invariants, the Vassiliev numbers, arise in higher-order terms of the expansion, and can be written in a form which shows them to be generalizations of the linking number.
Excitation of knotted vortex lines in matter waves
Maucher, F.; Gardiner, S. A.; Hughes, I. G.
2016-06-01
We study the creation of knotted ultracold matter waves in Bose-Einstein condensates via coherent two-photon Raman transitions with a Λ level configuration. The Raman transition allows an indirect transfer of atoms from the internal state | a> to the target state | b> via an excited state | e> , that would be otherwise dipole-forbidden. This setup enables us to imprint three-dimensional knotted vortex lines embedded in the probe field to the density in the target state. We elaborate on experimental feasibility as well as on subsequent dynamics of the matter wave.
Root - knot nematodes on summer vegetables in North Tunisia
Moens, M.
1985-01-01
Full Text Available The influence of different factors on the root-knot nematode infestation and on the yield of tomato have been examined : date of planting, cultivar choice, rotation scheme and soil disinfestation. It was found that the earliest planting date gave the highest yield but also the most severe root galling on susceptible tomato cultivars. A cropping sequence where wheat is alternated with tomatoes was not sufficient for reducing root-knot nematode population to a level permitting the cropping of a susceptible tomato cultivar. Long rotations with non host crops should be used. Soil treatment with certain nematicides significantly reduced the root galling and improved the yield.
Successful Treatment of Stent Knot in the Proximal Ureter Using Ureteroscopy and Holmium Laser
Masters M. Richards
2011-01-01
Full Text Available Knotted ureteral stent is rare yet tedious complication that might represent a treatment challenge to the endourologist. Only twelve cases of knotted stent have been reported. Different management options have been reported, including simple traction, ureteroscopy, percutaneous removal, and open surgery. In this paper, we present the successful untying of the knot using ureteroscopy with holmium laser.
The Mental Manipulation of 2-D Representations of Knots as Deformable Structures.
McLeay, Heather; Piggins, David
1996-01-01
Spatial tests involving the comparison of diagrams of interlaced ropes or knots at varying orientations were given to (n=21) subjects, mostly English college undergraduates, to determine an ordering in terms of complexity of tasks involving the mental manipulation of the knots. Certain knot shapes were processed faster than others and greater…
Vanessa Resende Nogueira Cruvinel
2012-06-01
Full Text Available OBJECTIVES: The aim of this study was to evaluate the prevalence of enamel defects and their risk factors on primary and permanent dentitions of prematurely born children and full-term born children born at Regional Hospital of Asa Sul, Brasília, DF, Brazil. MATERIAL AND METHODS: Eighty 5-10-year-old children of both genders were examined, being 40 born prematurely (G1 and 40 born full term (G2. The demographic variables, medical history and oral health behaviors were retrieved using a questionnaire and data obtained from clinical examination were recorded. The teeth were examined and the presence of enamel defects was diagnosed according to the DDE Index and registered in odontograms. Subsequently, the defects were categorized in four groups according to one of the criteria proposed in 1992 by the FDI Commission on Oral Health, Research and Epidemiology. Kruskal-Wallis, Chi-square, Kappa, Mann-Whitney tests and logistic regression were used for statistical analysis. RESULTS: 75% of total sample had enamel defects. There was a major prevalence of hypoplasia of the enamel in G1 (p<0.001. There was a significant relationship between low weight and presence of the imperfections on the enamel in G1 on the primary dentition. The logistic regression model showed that the other risk factors such as monthly per capita family income, educational level, dietary and hygiene habits, fluoride exposure, trauma, and diseases were not associated with enamel defects and caries. CONCLUSIONS: Pre-term labor can be a predisposing factor for the presence of the enamel hypoplasia in the primary dentition.
Nanoscale adhesion forces between enamel pellicle proteins and hydroxyapatite.
Vukosavljevic, D; Hutter, J L; Helmerhorst, E J; Xiao, Y; Custodio, W; Zaidan, F C; Oppenheim, F G; Siqueira, W L
2014-05-01
The acquired enamel pellicle (AEP) is important for minimizing the abrasion caused by parafunctional conditions as they occur, for instance, during bruxism. It is a remarkable feature of the AEP that a protein/peptide film can provide enough protection in normofunction to prevent teeth from abrasion and wear. Despite its obvious critical role in the protection of tooth surfaces, the essential adhesion features of AEP proteins on the enamel surface are poorly characterized. The objective of this study was to measure the adhesion force between histatin 5, a primary AEP component, and hydroxyapatite (HA) surfaces. Both biotinylated histatin 5 and biotinylated human serum albumin were allowed to adsorb to streptavidin-coated silica microspheres attached to atomic force microscope (AFM) cantilevers. A multimode AFM with a Nanoscope IIIa controller was used to measure the adhesion force between protein-functionalized silica microspheres attached to cantilever tips and the HA surface. The imaging was performed in tapping mode with a Si3N4 AFM cantilever, while the adhesion forces were measured in AFM contact mode. A collection of force-distance curves (~3,000/replicate) was obtained to generate histograms from which the adhesion forces between histatin 5 or albumin and the HA surface were measured. We found that histatin 5 exhibited stronger adhesion forces (90% >1.830 nN) to the HA surface than did albumin (90% > 0.282 nN). This study presents an objective approach to adhesion force measurements between histatin 5 and HA, and provides the experimental basis for measuring the same parameters for other AEP constituents. Such knowledge will help in the design of synthetic proteins and peptides with preventive and therapeutic benefits for tooth enamel.
Controlled Deposition of HAp Mimicking Tooth Enamel
无
2005-01-01
Chemical compositions and microsturcture of mature human tooth enamel were investigated by XRD , FTIR and SEM to further understand the characteristics of tooth enamel. In order to obtain apatite crystals chemically and structurally similar to those in tooth enamel, biomimetic way was employed. Selfassembled monolyers terminated with-SO3 H groups were used as deposition substrates and 1.5 SBF ( the concentrations of Ca2+ and PO43- ions 1.5 times than those in simulated body fluid ) with and without 5 ppm F- were used as soaking medium. The XRD and FTIR results showed that both the deposited fluoride-substituted hydroxyapatite( F-HAp ) crystals in 1.5 SBF with F- and hydroxyapatite ( HAp ) crystals in 1.5 SBF were carbonate-containing, mimicking human tooth enamel in chemical compositions. The SEM photos showed that needle-like F-HAp crystals bad large aspect ratios and grew in bundles, which were similar to the crystals in human tooth enamel.The results provide available information on dental restoration.
Enamel color changes following orthodontic treatment
Akshaya Pandian
2017-01-01
Full Text Available Objective: To evaluate and compare the effect of various orthodontic bonding systems and clean up procedures on quantitative enamel colour change. Materials and Methods: A literature search was done to identify the studies that assessed the quantitative enamel colour change associated with the various bonding systems and cleanup procedures. Electronic database (Pub Med, Cochrane and Google Scholar were searched. First stage screening was performed and the abstracts were selected according to the initial selection criteria. Full text articles were retrieved and analyzed during second stage screening. The bibliographies were reviewed to identify additional relevant studies. Results: Sixteen full text articles were retrieved. Six were rejected because the methodology was different. There was significant enamel colour change following orthodontic bonding, debonding and clean up procedures. Conclusion: Self–etching primers produce less enamel colour change compared to conventional etching. Resin Modified GIC produces least colour change compared to other light cure and chemical cure systems. Polishing following the clean-up procedure reduces the colour change of the enamel.
Enamel microabrasion: An overview of clinical and scientific considerations
Pini, Núbia Inocencya Pavesi; Sundfeld-Neto, Daniel; Aguiar, Flavio Henrique Baggio; Sundfeld, Renato Herman; Martins, Luis Roberto Marcondes; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite
2015-01-01
Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface wi...
In vitro inhibition of bovine enamel demineralization by enamel matrix derivative.
Ran, Jin Mei; Ieong, Cheng Cheng; Xiang, Chen Yang; Lv, Xue Ping; Xue, Jing; Zhou, Xue Dong; Li, Wei; Zhang, Ling Lin
2014-01-01
This study aimed to determine whether enamel matrix derivative (Emdogain) affects the demineralization of bovine enamel in vitro and to assess the agent's anti-caries potential. Bovine enamel blocks were prepared and randomly divided into three groups (n = 15 per group), which were treated with distilled water (negative control), NaF (positive control), or Emdogain. All three groups were pH-cycled 12 times over 6 days. The percentage of surface enamel microhardness reduction (%SMHR), calcium demineralization rate (CDR), surface roughness, lesion depth and mineral loss after demineralization were examined. Surface morphology of specimens was studied by scanning electron microscopy. The Emdogain and positive control groups showed similar surface roughness, lesion depths and mineral loss, which were significantly lower than those in the negative control group. In addition, the enamel surfaces of both the Emdogain and NaF groups showed much narrower intercrystalline spaces than the surfaces of the negative control group, which exhibited extensive microfractures along the crystal edges. %SMHR differed significantly among all three groups, with the smallest value in the Emdogain group and the greatest in the negative control group. These results indicate that enamel matrix derivative (Emdogain) can significantly inhibit demineralization of bovine enamel in vitro, suggesting that it has potential as an anti-caries agent.
Effect of Removal of Enamel on Rebonding Strength of Resin Composite to Enamel
L. Kilponen
2016-01-01
Full Text Available Objective. To examine the effect of removing the surface layer of enamel on the rebonding strength of resin composite. Methods. Teeth in four groups (n=10 were etched, a small amount of resin composite was bonded and debonded, then specimens in three groups were ground for different lengths of time (10 s, 20 s, 30 s to remove an increasing amount of enamel, one group was left untouched. The teeth were bonded again and the bond strengths of 1st and 2nd bonding were compared and analysed against the amount of enamel loss in different groups (7 µm (±2; 12 µm (±1; 16 µm (±3. Specimens were examined with SEM and by noncontacting optical profilometer. Results. Although results indicated higher rebonding strength with increasing enamel removal ANOVA showed low statistical differences between the groups (p>0.05. However, values between first bonding and rebonding strengths differed significantly (p<0.05 in the group that was not ground. SEM revealed that enamel-surfaces that were ground after debonding etched well, compared to the surfaces that still contained adhesive remnants. Conclusions. Removal of small amount of enamel refreshed the surface for rebonding. Rebonding strengths without grinding the surface before bonding were lower than bond strength to intact enamel.
Effect of Removal of Enamel on Rebonding Strength of Resin Composite to Enamel
Lassila, L.; Varrela, J.; Vallittu, P. K.
2016-01-01
Objective. To examine the effect of removing the surface layer of enamel on the rebonding strength of resin composite. Methods. Teeth in four groups (n = 10) were etched, a small amount of resin composite was bonded and debonded, then specimens in three groups were ground for different lengths of time (10 s, 20 s, 30 s) to remove an increasing amount of enamel, one group was left untouched. The teeth were bonded again and the bond strengths of 1st and 2nd bonding were compared and analysed against the amount of enamel loss in different groups (7 µm (±2); 12 µm (±1); 16 µm (±3)). Specimens were examined with SEM and by noncontacting optical profilometer. Results. Although results indicated higher rebonding strength with increasing enamel removal ANOVA showed low statistical differences between the groups (p > 0.05). However, values between first bonding and rebonding strengths differed significantly (p < 0.05) in the group that was not ground. SEM revealed that enamel-surfaces that were ground after debonding etched well, compared to the surfaces that still contained adhesive remnants. Conclusions. Removal of small amount of enamel refreshed the surface for rebonding. Rebonding strengths without grinding the surface before bonding were lower than bond strength to intact enamel. PMID:27725932
Morphology of the cemento-enamel junction in premolar teeth.
Arambawatta, Kapila; Peiris, Roshan; Nanayakkara, Deepthi
2009-12-01
The present study attempted to describe the distribution of the mineralized tissues that compose the cemento-enamel junction, with respect to both the different types of permanent premolars of males and females and the various surfaces of individual teeth. The cervical region of ground sections of 67 premolars that had been extracted for orthodontic reasons were analyzed using transmitted light microscopy to identify which of the following tissue interrelationships was present at the cemento-enamel junction: cementum overlapping enamel; enamel overlapping cementum; edge-to-edge relationship between cementum and enamel; or the presence of gaps between the enamel and cementum with exposed dentin. An edge-to-edge interrelation between root cementum and enamel was predominant (55.1%). In approximately one-third of the sample, gaps between cementum and enamel with exposed dentin were observed. Cementum overlapping enamel was less prevalent than previously reported, and enamel overlapping cementum was seen in a very small proportion of the sample. In any one tooth, the distribution of mineralized tissues at the cemento-enamel junction was irregular and unpredictable. The frequency of gaps between enamel and cementum with exposure of dentin was higher than previously reported, which suggests that this region is fragile and strongly predisposed to pathological changes. Hence, this region should be protected and carefully managed during routine clinical procedures such as dental bleaching, orthodontic treatment, and placement of restorative materials.
Spontaneous knot; a rare cause of ventriculoperitoneal shunt blockage.
Mohammed, Wail
2012-02-01
A 14-year old X linked congenital hydrocephalus presented with unexplained headaches and vomiting. He had external ventricular drain and intracranial pressure monitoring (ICP). Subsequently, he underwent exploration and removal of previously inserted ventriculoperitoneal (VP) shunts. On retrieval of peritoneal catheters a double knot was noted between his two distal catheters. This case illustrates a rare cause of ventriculoperitoneal shunt malfunction.
Integrated management of root-knot nematode (Meloidogyne ...
(p<0.05) the nematode egg hatching as well as juvenile motility over the untreated control. Higher ... the pot house experiment. .... and placed to a drop of glycerine on a clean glass slide with ... knot nematode for subsequent experiments in the.
Knot energy in unstretching ergodic magnetic flux tubes
de Andrade, Garcia
2009-01-01
Recently Titov et al [ApJ \\textbf{693},(2009) and ApJ (2007)] have made use of a covariant model to investigate magnetic reconnection of astrophysical plasmas. Earlier R Ricca [Phys Rev A (1991)] has used another covariant formalism, to investigated vortex filaments and solitons. This formalism, called Ricci rotation coefficients (RRC), is applied here, to the Chui and Moffatt [PRSA (1995)] knotted magnetic flux tube (MFT) Riemann metric in the case of vanishing stretch. It is shown that, the vanishing of some components of the (RRC) leads to unstretching knotted tubes. Computing of magnetic knot energy in terms of the RCC, shows that, uniform, unstretching and constant cross-section tubes leads to a marginal dynamo action over magnetic surfaces. Recent investigation on the role of stretching in plasma dynamo action showed that in diffusive media [Phys Plasma \\textbf{14} (2008)], unstretching unknotted tubes would not support fast dynamo action. This result was generalized here to much more general knotted MF...
Spontaneous knot; a rare cause of ventriculoperitoneal shunt blockage.
Mohammed, Wail
2011-02-01
A 14-year old X linked congenital hydrocephalus presented with unexplained headaches and vomiting. He had external ventricular drain and intracranial pressure monitoring (ICP). Subsequently, he underwent exploration and removal of previously inserted ventriculoperitoneal (VP) shunts. On retrieval of peritoneal catheters a double knot was noted between his two distal catheters. This case illustrates a rare cause of ventriculoperitoneal shunt malfunction.
The unique cysteine knot regulates the pleotropic hormone leptin.
Ellinor Haglund
Full Text Available Leptin plays a key role in regulating energy intake/expenditure, metabolism and hypertension. It folds into a four-helix bundle that binds to the extracellular receptor to initiate signaling. Our work on leptin revealed a hidden complexity in the formation of a previously un-described, cysteine-knotted topology in leptin. We hypothesized that this unique topology could offer new mechanisms in regulating the protein activity. A combination of in silico simulation and in vitro experiments was used to probe the role of the knotted topology introduced by the disulphide-bridge on leptin folding and function. Our results surprisingly show that the free energy landscape is conserved between knotted and unknotted protein, however the additional complexity added by the knot formation is structurally important. Native state analyses led to the discovery that the disulphide-bond plays an important role in receptor binding and thus mediate biological activity by local motions on distal receptor-binding sites, far removed from the disulphide-bridge. Thus, the disulphide-bridge appears to function as a point of tension that allows dissipation of stress at a distance in leptin.
True Umbilical Cord Knot Leading to Fetal Demise
She had onset of labor at a GA of 40 weeks and 5 days following cervical ripening ... the baby. We have reported a case of true umbilical cord knot in Nnewi, South‑East Nigeria. .... Besides, other possible reasons for the fetal demise could not.
Polynomial Invariants of Torus Knots and (p,q)-Calculus
Pavlyuk, Anatoliy M.
2016-01-01
We introduce the deformed fermionic numbers, corresponding to the skein relations, the main characteristics of knots and links. These fermionic numbers allow one to restore the skein relations. For the Alexander (Jones) skein relation we introduce corresponding Alexander (Jones) fermionic q-numbers, and for the HOMFLY skein relation - the HOMFLY deformed (p,q)-numbers with one fermionic parameter.
Factorization of colored knot polynomials at roots of unity
Kononov, Ya.; Morozov, A.
2015-07-01
HOMFLY polynomials are the Wilson-loop averages in Chern-Simons theory and depend on four variables: the closed line (knot) in 3d space-time, representation R of the gauge group SU (N) and exponentiated coupling constant q. From analysis of a big variety of different knots we conclude that at q, which is a 2m-th root of unity, q2m = 1, HOMFLY polynomials in symmetric representations [ r ] satisfy recursion identity: Hr+m =Hr ṡHm for any A =qN, which is a generalization of the property Hr = H1r for special polynomials at m = 1. We conjecture a further generalization to arbitrary representation R, which, however, is checked only for torus knots. Next, Kashaev polynomial, which arises from HR at q2 = e 2 πi / | R |, turns equal to the special polynomial with A substituted by A| R |, provided R is a single-hook representations (including arbitrary symmetric) - what provides a q - A dual to the similar property of Alexander polynomial. All this implies non-trivial relations for the coefficients of the differential expansions, which are believed to provide reasonable coordinates in the space of knots - existence of such universal relations means that these variables are still not unconstrained.
Factorization of colored knot polynomials at roots of unity
Ya. Kononov
2015-07-01
Full Text Available HOMFLY polynomials are the Wilson-loop averages in Chern–Simons theory and depend on four variables: the closed line (knot in 3d space–time, representation R of the gauge group SU(N and exponentiated coupling constant q. From analysis of a big variety of different knots we conclude that at q, which is a 2m-th root of unity, q2m=1, HOMFLY polynomials in symmetric representations [r] satisfy recursion identity: Hr+m=Hr⋅Hm for any A=qN, which is a generalization of the property Hr=H1r for special polynomials at m=1. We conjecture a further generalization to arbitrary representation R, which, however, is checked only for torus knots. Next, Kashaev polynomial, which arises from HR at q2=e2πi/|R|, turns equal to the special polynomial with A substituted by A|R|, provided R is a single-hook representations (including arbitrary symmetric – what provides a q−A dual to the similar property of Alexander polynomial. All this implies non-trivial relations for the coefficients of the differential expansions, which are believed to provide reasonable coordinates in the space of knots – existence of such universal relations means that these variables are still not unconstrained.
Effect of fluoride toothpastes on enamel demineralization
Gintner Zeno
2006-06-01
Full Text Available Abstract Background It was the aim of this study to investigate the effect of four different toothpastes with differing fluoride compounds on enamel remineralization. Methods A 3 × 3 mm window on the enamel surface of 90 human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 6 groups and the lower half of the window was covered with varnish serving as control. The teeth were immersed in a toothpaste slurry containing: placebo tooth paste (group 1; remineralization solution (group 2; Elmex Anticaries (group 3; Elmex Sensitive (group 4; Blend-a-med Complete (group 5 and Colgate GRF (group 6. Ten teeth of each group were used for the determination of the F- content in the superficial enamel layer and acid solubility of enamel expressed in soluble phosphorus. Of 6 teeth of each group serial sections were cut and investigated with polarization light microscopy (PLM and quantitative energy dispersive X-ray analysis (EDX. Results The PLM results showed an increased remineralization of the lesion body in the Elmex Anticaries, Elmex Sensitive and Colgate GRF group but not in the Blend-a-med group. A statistically significant higher Ca content was found in the Elmex Anticaries group. The fluoride content in the superficial enamel layer was significantly increased in both Elmex groups and the Blend-a-med group. Phosphorus solubility was significantly decreased in both Elmex groups and the Blend-a-med group. Conclusion It can be concluded that amine fluoride compounds in toothpastes result in a clearly marked remineralization of caries like enamel lesions followed by sodium fluoride and sodium monofluorophosphate formulations.
Constructing a polynomial whose nodal set is the three-twist knot 52
Dennis, Mark R.; Bode, Benjamin
2017-06-01
We describe a procedure that creates an explicit complex-valued polynomial function of three-dimensional space, whose nodal lines are the three-twist knot 52. The construction generalizes a similar approach for lemniscate knots: a braid representation is engineered from finite Fourier series and then considered as the nodal set of a certain complex polynomial which depends on an additional parameter. For sufficiently small values of this parameter, the nodal lines form the three-twist knot. Further mathematical properties of this map are explored, including the relationship of the phase critical points with the Morse-Novikov number, which is nonzero as this knot is not fibred. We also find analogous functions for other simple knots and links. The particular function we find, and the general procedure, should be useful for designing knotted fields of particular knot types in various physical systems.
Enamel Hypomineralization and Structural Defects in Amelotin-deficient Mice.
Nakayama, Y; Holcroft, J; Ganss, B
2015-05-01
Amelotin (AMTN) is a relatively recently discovered enamel protein that is predominantly expressed by ameloblasts during the maturation stage of amelogenesis and is present at lower levels in the junctional epithelium of erupted teeth. Previous studies have suggested a function of this protein in enamel mineralization and cell attachment. Genetic mouse models have been instrumental in defining the role of many enamel-related proteins, but a genetic mouse model lacking the Amtn gene has not been reported. Here, we describe the generation of amelotin-deficient mice and the analysis of their enamel phenotype in comparison with that of wild-type animals. Ablation of AMTN expression resulted in mechanically inferior enamel of mandibular incisors that showed chipping and fractures at the incisal edge. Enamel mineralization was delayed, resulting in hypomineralized inner enamel and structural defects in the outer enamel. Erupted enamel close to the gingival margin showed increased surface roughness. The expression levels of the enamel matrix proteins AMEL, AMBN, ENAM, and ODAM and the enamel proteases MMP-20 and KLK-4 were not significantly altered, although the expression of KLK-4 was delayed. The morphology of ameloblasts showing prominent Tomes' processes during the secretory stage was not altered, and there was no indication of disruption of cell structures or activities, but a residual layer, presumably consisting of organic material, remained at the enamel surface close to the gingival margin. The integrity of the dentogingival attachment at the junctional epithelium appeared unaffected by AMTN deficiency. These observations indicate that AMTN plays a subtle yet critical role in enamel biomineralization, particularly during the establishment of the outer and surface enamel layers. This role appears to be largely independent of other enamel proteins.
Restitution of enamel after interdental stripping.
Lundgren, T; Milleding, P; Mohlin, B; Nannmark, U
1993-01-01
This paper studies the effect of interdental stripping on the enamel surface and evaluates methods to restitute the treated surface. Extracted teeth mounted in a semielastic material were subjected to stripping by different kinds of steel strips. The treated enamel surfaces were then polished in several different ways. The effects were studied by SEM and profilometry. It was concluded that the coarsest strips produced irregularities of such a magnitude that polishing had very limited effect. Polishing starting with coarse polishing strips followed by gradually finer gave the best result. An increase in number of strokes and use of all grades of polishing strips slightly improved the result.
Survey of coatings for solar collectors. [ceramic enamels and chromium
Mcdonald, G. E.
1974-01-01
Ceramic enamel is found to be more solar selective, (i.e., has high solar absorptance in combination with low infrared emittance) than organic enamel, but neither is as solar selective as black chrome, black copper, black zinc, or black nickel. Ceramic enamel is matched only by black chrome in durability and wide availability. Ceramic enamel and organic enamel have approximately the same cost, and both are currently slightly lower in cost than black chrome, black copper, or black zinc. Black nickel is relatively unavailable and, because of that, realistic cost comparisons are not possible.
The Crystal Characteristics of Enamel and Dentin by XRD Method
无
2006-01-01
Crystal characteristics of tooth enamel and dentin were investigated using XRD, SEM, and EPMA methods.The results show that the mineral phase in enamel is HA and in dentin is HA and minor whitlock ites.The dentin HA and the enamel HA have different crystallinity, the crystallinity of enamel HA is much higher than that of dentin HA.The average particle size of the enamel HA and dentin HA are 897A and 309A, respectively.The HA in enamel is regularly arranged, and in dentin the arrangement of HA is diifferent from the enamel HA in the same section.Both the enamel and the dentin are mainly consisted of Ca, P, O, and C, and the trace elements Mg , Sr, Al, Na , and K.The dentin contains more trace elements than the enamel.However,the incorporation of trace elements in both dentin and enamel are very limited.Other impurities such as F and Cl are less than their detection limit.The a and c values of enamel HA are 9.433A and 6.8A, and those of thedentin HA are 9.498A and 6.896A, respectively.The expansion in a value results from those the larger size of [CO3 ]2 group substituing for the smaller [ OH]- group in the channel, and replacement of [ OH ]- by[ CO3 ]2- dominates the change in cell parameter, taking into account of other trace elements.
Size dependent elastic modulus and mechanical resilience of dental enamel.
O'Brien, Simona; Shaw, Jeremy; Zhao, Xiaoli; Abbott, Paul V; Munroe, Paul; Xu, Jiang; Habibi, Daryoush; Xie, Zonghan
2014-03-21
Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For example, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained.
Ceramic-like wear behaviour of human dental enamel.
Arsecularatne, J A; Hoffman, M
2012-04-01
This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth. Copyright Â© 2011 Elsevier Ltd. All rights reserved.
Helium ion microscopy of enamel crystallites and extracellular tooth enamel matrix
Felicitas B Bidlack
2014-10-01
Full Text Available An unresolved problem in tooth enamel studies has been to analyze simultaneously and with sufficient spatial resolution both mineral and organic phases in their three dimensional (3D organization in a given specimen. This study aims to address this need using high-resolution imaging to analyze the 3D structural organization of the enamel matrix, especially amelogenin, in relation to forming enamel crystals. Chemically fixed hemi-mandibles from wild type mice were embedded in LR White acrylic resin, polished and briefly etched to expose the organic matrix in developing tooth enamel. Full-length amelogenin was labeled with specific antibodies and 10 nm immuno-gold. This allowed us to use and compare two different high-resolution imaging techniques for the analysis of uncoated samples. Helium ion microscopy (HIM was applied to study the spatial organization of organic and mineral structures, while field emission scanning electron microscopy (FE-SEM in various modes, including backscattered electron detection, allowed us to discern the gold-labeled proteins. Wild type enamel in late secretory to early maturation stage reveals adjacent to ameloblasts a lengthwise parallel alignment of the enamel matrix proteins, including full-length amelogenin proteins, which then transitions into a more heterogeneous appearance with increasing distance from the mineralization front. The matrix adjacent to crystal bundles forms a smooth and lacey sheath, whereas between enamel prisms it is organized into spherical components that are interspersed with rod-shaped protein. These findings highlight first, that the heterogeneous organization of the enamel matrix can be visualized in mineralized en bloc samples. Second, our results illustrate that the combination of these techniques is a powerful approach to elucidate the 3D structural organization of organic matrix molecules in mineralizing tissue in nanometer resolution.
Amelogenin-Ameloblastin Spatial Interaction around Maturing Enamel Rods.
Mazumder, P; Prajapati, S; Bapat, R; Moradian-Oldak, J
2016-08-01
Amelogenin and ameloblastin are 2 extracellular matrix proteins that are essential for the proper development of enamel. We recently reported that amelogenin and ameloblastin colocalized during the secretory stage of enamel formation when nucleation of enamel crystallites occurs. Direct interactions between the 2 proteins have been also demonstrated in our in vitro studies. Here, we explore interactions between their fragments during enamel maturation. We applied in vivo immunofluorescence imaging, quantitative co-localization analysis, and a new FRET (fluorescence resonance energy transfer) technique to demonstrate ameloblastin and amelogenin interaction in the maturing mouse enamel. Using immunochemical analysis of protein samples extracted from 8-d-old (P8) first molars from mice as a model for maturation-stage enamel, we identified the ~17-kDa ameloblastin (Ambn-N) and the TRAP (tyrosine-rich amelogenin peptide) fragments. We used Ambn-N18 and Ambn-M300 antibodies raised against the N-terminal and C-terminal segments of ameloblastin, as well as Amel-FL and Amel-C19 antibodies against full-length recombinant mouse amelogenin (rM179) and C-terminal amelogenin, respectively. In transverse sections, co-localization images of N-terminal fragments of amelogenin and ameloblastin around the prism boundary revealed the "fish net" pattern of the enamel matrix. Using in vivo FRET microscopy, we further demonstrated spatial interactions between amelogenin and ameloblastin N-terminal fragments. In the maturing mouse enamel, the association of these residual protein fragments created a discontinuity between enamel rods, which we suggest is important for support and maintenance of enamel rods and eventual contribution to unique enamel mechanical properties. We present data that support cooperative functions of enamel matrix proteins in mediating the structural hierarchy of enamel and that contribute to our efforts to design and develop enamel biomimetic material.
Enamel for high-temperature superalloys
Levin, H.; Lent, W. E.
1977-01-01
Desired optical and high temperature enamel properties are obtained with glasses prepared from the system Li2O-ZrO2-nSiO2. Molar compositions range from n=4 to n=1.3, to which are added minor amounts in varying combinations of alumina, alkali fluorides, boric oxide, alkali oxides, and akaline earth oxides.
Enamel surface changes caused by hydrogen sulfide
Takao Yamaguchi
2015-01-01
Conclusions: Our findings suggested that H 2 S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations.
Enamel surface remineralization: Using synthetic nanohydroxyapatite
J Shanti Swarup
2012-01-01
Full Text Available Objective: The purpose of this study was to evaluate the effects of synthetically processed hydroxyapatite particles in remineralization of the early enamel lesions in comparison with 2% sodium fluoride. Materials and Methods: Thirty sound human premolars were divided into nanohydroxyapatite group (n0 = 15 and the sodium fluoride group (n = 15. The specimens were subjected to demineralization before being coated with 10% aqueous slurry of 20 nm nanohydroxyapatite or 2% sodium fluoride. The remineralizing efficacy of the materials was evaluated using surface microhardness (SMH measurements, scanning microscopic analysis and analysis of the Ca/P ratio of the surface enamel. Data analysis was carried out using paired t-test and independent t-test. Results: The results showed that the nanohydroxyapatite group produced a surface morphology close to the biologic enamel, the increase in mineral content (Ca/P ratio was more significant in the nanohydroxyapatite group ( P 0.05. Conclusion: The use of biomimetic nanohydroxyapatite as a remineralizing agent holds promise as a new synthetic enamel biocompatible material to repair early carious lesions.
Tooth enamel hypoplasia in PHACE syndrome.
Chiu, Yvonne E; Siegel, Dawn H; Drolet, Beth A; Hodgson, Brian D
2014-01-01
Individuals with PHACE syndrome (posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye abnormalities, sternal cleft, and supraumbilical raphe syndrome) have reported dental abnormalities to their healthcare providers and in online forums, but dental involvement has not been comprehensively studied. A study was conducted at the third PHACE Family Conference, held in Milwaukee, Wisconsin, in July 2012. A pediatric dentist examined subjects at enrollment. Eighteen subjects were enrolled. The median age was 4.2 years (range 9 mos-9 yrs; 14 girls, 4 boys). Eleven of 18 patients had intraoral hemangiomas and five of these (50%) had hypomature enamel hypoplasia. None of the seven patients without intraoral hemangiomas had enamel hypoplasia. No other dental abnormalities were seen. Enamel hypoplasia may be a feature of PHACE syndrome when an intraoral hemangioma is present. Enamel hypoplasia increases the risk of caries, and clinicians should refer children with PHACE syndrome to a pediatric dentist by 1 year of age.
Direct observation of DNA knots using a solid-state nanopore
Plesa, Calin; Verschueren, Daniel; Pud, Sergii; van der Torre, Jaco; Ruitenberg, Justus W.; Witteveen, Menno J.; Jonsson, Magnus P.; Grosberg, Alexander Y.; Rabin, Yitzhak; Dekker, Cees
2016-12-01
Long DNA molecules can self-entangle into knots. Experimental techniques for observing such DNA knots (primarily gel electrophoresis) are limited to bulk methods and circular molecules below 10 kilobase pairs in length. Here, we show that solid-state nanopores can be used to directly observe individual knots in both linear and circular single DNA molecules of arbitrary length. The DNA knots are observed as short spikes in the nanopore current traces of the traversing DNA molecules and their detection is dependent on a sufficiently high measurement resolution, which can be achieved using high-concentration LiCl buffers. We study the percentage of molecules with knots for DNA molecules of up to 166 kilobase pairs in length and find that the knotting occurrence rises with the length of the DNA molecule, consistent with a constant knotting probability per unit length. Our experimental data compare favourably with previous simulation-based predictions for long polymers. From the translocation time of the knot through the nanopore, we estimate that the majority of the DNA knots are tight, with remarkably small sizes below 100 nm. In the case of linear molecules, we also observe that knots are able to slide out on application of high driving forces (voltage).
Kelvin Waves and Dynamic Knots on Perturbative Helical Vortex Lines
Kou, Su-Peng
2016-01-01
Vortex lines are one-dimensional extended objects in three-dimensional superfluids. Vortex lines have many interesting properties, including Kelvin waves, exotic statistics, and possible entanglement. In this paper, an emergent "quantum world" is explored by projecting helical vortex lines. A one-dimensional quantum Fermionic model is developed to effectively describe the local fluctuations of helical vortex lines. The elementary excitations are knots with half winding-number that obey emergent quantum mechanics. The Biot-Savart equation, and its Kelvin wave solutions on helical vortex lines become Schrodinger equation, and the wave functions of probability waves for finding knots, respectively. This work shows an alternative approach to simulating quantum many-body physics based on classical systems.
BPS counting for knots and combinatorics on words
Kucharski, Piotr; Sułkowski, Piotr
2016-11-01
We discuss relations between quantum BPS invariants defined in terms of a product decomposition of certain series, and difference equations (quantum A-polynomials) that annihilate such series. We construct combinatorial models whose structure is encoded in the form of such difference equations, and whose generating functions (Hilbert-Poincaré series) are solutions to those equations and reproduce generating series that encode BPS invariants. Furthermore, BPS invariants in question are expressed in terms of Lyndon words in an appropriate language, thereby relating counting of BPS states to the branch of mathematics referred to as combinatorics on words. We illustrate these results in the framework of colored extremal knot polynomials: among others we determine dual quantum extremal A-polynomials for various knots, present associated combinatorial models, find corresponding BPS invariants (extremal Labastida-Mariño-Ooguri-Vafa invariants) and discuss their integrality.
Mutation on Knots and Whitney's 2-Isomorphism Theorem
Zhi Yun CHENG; Hong Zhu GAO
2013-01-01
Whitney's 2-switching theorem states that any two embeddings of a 2-connected planar graph in S2 can be connected via a sequence of simple operations,named 2-switching.In this paper,we obtain two operations on planar graphs from the view point of knot theory,which we will term "twisting" and "2-switching" respectively.With the twisting operation,we give a pure geometrical proof of Whitney's 2-switching theorem.As an application,we obtain some relationships between two knots which correspond to the same signed planar graph.Besides,we also give a necessary and sufficient condition to test whether a pair of reduced alternating diagrams are mutants of each other by their signed planar graphs.
SU(2)/SL(2) knot invariants and KS monodromies
Galakhov, D; Morozov, A
2015-01-01
We review the Reshetikhin-Turaev approach to construction of non-compact knot invariants involving R-matrices associated with infinite-dimensional representations, primarily those made from Faddeev's quantum dilogarithm. The corresponding formulas can be obtained from modular transformations of conformal blocks as their Kontsevich-Soibelman monodromies and are presented in the form of transcendental integrals, where the main issue is manipulation with integration contours. We discuss possibilities to extract more explicit and handy expressions which can be compared with the ordinary (compact) knot polynomials coming from finite-dimensional representations of simple Lie algebras, with their limits and properties. In particular, the quantum A-polynomials, difference equations for colored Jones polynomials should be the same, just in non-compact case the equations are homogeneous, while they have a non-trivial right-hand side for ordinary Jones polynomials.
The Faddeev knots as stable solitons:Existence theorems
LIN; Fanghua; YANG; Yisong
2004-01-01
The problem of existence of knot-like solitons as the energy-minimizing configurations in the Faddeev model, topologically characterized by an Hopf invariant, Q, is considered. It is proved that, in the full space situation, there exists an infinite set S of integers so that for any m ∈ S, the Faddeev energy, E, has a minimizer among the class Q = m; in the bounded domain situation, the same existence theorem holds when S is the set of all integers. One of the important technical results is that E and Q satisfy the sublinear inequality E ≤ C|Q|3/4, where C ＞0 is a universal constant, which explains why knotted (clustered soliton) configurations are preferred over widely separated unknotted (multisoliton) configurations when |Q| is sufficiently large.
Towards U(N|M) knot invariant from ABJM theory
Eynard, Bertrand
2014-01-01
We study U(N|M) character expectation value with the supermatrix Chern-Simons theory, known as the ABJM matrix model, with emphasis on its connection to the knot invariant. This average just gives the half BPS circular Wilson loop expectation value in ABJM theory, which shall correspond to the unknot invariant. We derive the determinantal formula, which gives U(N|M) character expectation values in terms of U(1|1) averages for a particular type of character representations. This means that the U(1|1) character expectation value is a building block for all the U(N|M) averages, and in particular, by an appropriate limit, for the U(N) invariants. In addition to the original model, we introduce another supermatrix model obtained through the symplectic transform, which is motivated by the torus knot Chern-Simons matrix model. We obtain the Rosso-Jones-type formula and the spectral curve for this case.
Design and performance of the APPLE-Knot undulator
Ji, Fuhao [Department of Physics, State Key Laboratory of Surface Physics, and Laboratory of Advanced Materials, Fudan University, 2005 Songhu Road, Shanghai 200438, People’s Republic of (China); Chang, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); Zhou, Qiaogen; Zhang, Wei [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Shanghai 201204, People’s Republic of (China); Ye, Mao [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); Sasaki, Shigemi [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Hiroshima 739-0046 (Japan); Qiao, Shan, E-mail: qiaoshan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); School of Physical Science and Technology, ShanghaiTech University, 319 Yueyang Road, Shanghai 200031, People’s Republic of (China)
2015-06-09
The design and performance of the Apple-Knot undulator which can generate photons with arbitrary polarization and low on-axis heat load are presented. Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.
Toward U(N|M) knot invariant from ABJM theory
Eynard, Bertrand; Kimura, Taro
2017-02-01
We study U(N|M) character expectation value with the supermatrix Chern-Simons theory, known as the ABJM matrix model, with emphasis on its connection to the knot invariant. This average just gives the half-BPS circular Wilson loop expectation value in ABJM theory, which shall correspond to the unknot invariant. We derive the determinantal formula, which gives U(N|M) character expectation values in terms of U(1|1) averages for a particular type of character representations. This means that the U(1|1) character expectation value is a building block for the U(N|M) averages and also, by an appropriate limit, for the U(N) invariants. In addition to the original model, we introduce another supermatrix model obtained through the symplectic transform, which is motivated by the torus knot Chern-Simons matrix model. We obtain the Rosso-Jones-type formula and the spectral curve for this case.
BPS counting for knots and combinatorics on words
Kucharski, Piotr
2016-01-01
We discuss relations between quantum BPS invariants defined in terms of a product decomposition of certain series, and difference equations (quantum A-polynomials) that annihilate such series. We construct combinatorial models whose structure is encoded in the form of such difference equations, and whose generating functions (Hilbert-Poincar\\'e series) are solutions to those equations and reproduce generating series that encode BPS invariants. Furthermore, BPS invariants in question are expressed in terms of Lyndon words in an appropriate language, thereby relating counting of BPS states to the branch of mathematics referred to as combinatorics on words. We illustrate these results in the framework of colored extremal knot polynomials: among others we determine dual quantum extremal A-polynomials for various knots, present associated combinatorial models, find corresponding BPS invariants (extremal Labastida-Mari\\~no-Ooguri-Vafa invariants) and discuss their integrality.
Infantile refsum disease with enamel defects: a case report.
Tran, Dorothy; Greenhill, William; Wilson, Stephen
2011-01-01
The purpose of this paper was to present the case of a 15-year-old female diagnosed with infantile Refsum disease (IRD) that presented with generalized enamel defects in the primary and permanent dentition. IRD is an inherited autosomal recessive disorder characterized by aberrant peroxisome function. IRD patients present with multiple clinical manifestations, including: retinitis pigmentosa; nystagmus; sensorineural hearing loss; mental and developmental delays; neuromotor defects; and cerebral ataxia. Craniofacial abnormalities reported include: high forehead; hypoplastic supraorbital ridges; epicanthal folds; midface hypoplasia; and large anterior fontanelle. At present, there is only one known report of dental anomaly associated with this syndrome. This represents the first known reported case in the pediatric dental literature.
The Preon Sector of the SLq(2) (Knot) Model
Finkelstein, Robert J
2013-01-01
We describe a Lagrangian defining the preon sector of the knot model. The preons are the elements of the fundamental representation of SLq(2). They exactly agree with the preons conjectured by Harari and Shupe. The coupling constants and masses required by this Lagrangian are in principle experimentally measurable. There is an alternative formulation of the kinematics permitting possible additional isotopic partners of the quarks.
The Knot Spectrum of Confined Random Equilateral Polygons
Diao Y.
2014-01-01
Full Text Available It is well known that genomic materials (long DNA chains of living organisms are often packed compactly under extreme confining conditions using macromolecular self-assembly processes but the general DNA packing mechanism remains an unsolved problem. It has been proposed that the topology of the packed DNA may be used to study the DNA packing mechanism. For example, in the case of (mutant bacteriophage P4, DNA molecules packed inside the bacteriophage head are considered to be circular since the two sticky ends of the DNA are close to each other. The DNAs extracted from the capsid without separating the two ends can thus preserve the topology of the (circular DNAs. It turns out that the circular DNAs extracted from bacteriophage P4 are non-trivially knotted with very high probability and with a bias toward chiral knots. In order to study this problem using a systematic approach based on mathematical modeling, one needs to introduce a DNA packing model under extreme volume confinement condition and test whether such a model can produce the kind of knot spectrum observed in the experiments. In this paper we introduce and study a model of equilateral random polygons con_ned in a sphere. This model is not meant to generate polygons that model DNA packed in a virus head directly. Instead, the average topological characteristics of this model may serve as benchmark data for totally randomly packed circular DNAs. The difference between the biologically observed topological characteristics and our benchmark data might reveal the bias of DNA packed in the viral capsids and possibly lead to a better understanding of the DNA packing mechanism, at least for the bacteriophage DNA. The purpose of this paper is to provide information about the knot spectrum of equilateral random polygons under such a spherical confinement with length and confinement ratios in a range comparable to circular DNAs packed inside bacteriophage heads.
Zeros of Jones polynomials for families of knots and links
Chang, S.-C.; Shrock, R.
2001-12-01
We calculate Jones polynomials VL( t) for several families of alternating knots and links by computing the Tutte polynomials T( G, x, y) for the associated graphs G and then obtaining VL( t) as a special case of the Tutte polynomial. For each of these families we determine the zeros of the Jones polynomial, including the accumulation set in the limit of infinitely many crossings. A discussion is also given of the calculation of Jones polynomials for non-alternating links.
Ectopic expression of dentin sialoprotein during amelogenesis hardens bulk enamel.
White, Shane N; Paine, Michael L; Ngan, Amanda Y W; Miklus, Vetea G; Luo, Wen; Wang, HongJun; Snead, Malcolm L
2007-02-23
Dentin sialophosphpoprotein (Dspp) is transiently expressed in the early stage of secretory ameloblasts. The secretion of ameloblast-derived Dspp is short-lived, correlates to the establishment of the dentinoenamel junction (DEJ), and is consistent with Dspp having a role in producing the specialized first-formed harder enamel adjacent to the DEJ. Crack diffusion by branching and dissipation within this specialized first-formed enamel close to the DEJ prevents catastrophic interfacial damage and tooth failure. Once Dspp is secreted, it is subjected to proteolytic cleavage that results in two distinct proteins referred to as dentin sialoprotein (Dsp) and dentin phosphoprotein (Dpp). The purpose of this study was to investigate the biological and mechanical contribution of Dsp and Dpp to enamel formation. Transgenic mice were engineered to overexpress either Dsp or Dpp in their enamel organs. The mechanical properties (hardness and toughness) of the mature enamel of transgenic mice were compared with genetically matched and age-matched nontransgenic animals. Dsp and Dpp contributions to enamel formation greatly differed. The inclusion of Dsp in bulk enamel significantly and uniformly increased enamel hardness (20%), whereas the inclusion of Dpp weakened the bulk enamel. Thus, Dsp appears to make a unique contribution to the physical properties of the DEJ. Dsp transgenic animals have been engineered with superior enamel mechanical properties.
Colored knot amplitudes and Hall-Littlewood polynomials
Shakirov, Sh
2013-01-01
The amplitudes of refined Chern-Simons (CS) theory, colored by antisymmetric (or symmetric) representations, conjecturally generate the Lambda^r- (or S^r-) colored triply graded homology of (n,m) torus knots. This paper is devoted to the generalization of Rosso-Jones formula to refined amplitudes, that involves non-trivial Gamma-factors -- expansion coefficients in the Macdonald basis. We derive from refined CS theory a linear recursion w.r.t. transformations (n,m) -> (n, n+m) and (n,m) -> (m,-n) that fully determines these factors. Applying this recursion to (n,nk+1) torus knots colored by antisymmetric representations [1^r] we prove that their amplitudes are rectangular [n^r] Hall-Littlewood polynomials under k units of framing (a.k.a. the Garsia-Haiman nabla) operator. For symmetric representations [r], we find the dual -- q-Whittaker -- polynomials. These results confirm and give a colored extension of the observation of arXiv:1201.3339 that triply graded homology of many torus knots has a strikingly simp...
Enamelin Directs Crystallite Organization at the Enamel-Dentine Junction.
Siddiqui, S; Al-Jawad, M
2016-05-01
Enamel is an acellular material formed by the intricate process of amelogenesis. Disruption caused at the initial stages of development, by means of mutations in the ENAM gene encoding the enamelin protein, results in enamel hypoplasia. Little is known about the consequence of ENAM mutation on the enamel structure at a crystallographic level. The aim of this study was to characterize the structure of ENAM-mutated enamel to develop a deeper understanding of the role of enamelin protein during formation with regard to crystal organization. Synchrotron X-ray microdiffraction (SXRD) and scanning electron microscopy (SEM) have been used to measure and correlate enamel crystallography and microstructure in hypoplastic and healthy enamel. Rietveld refinement carried out on 2-dimensional diffraction patterns, collected from the Advanced Photon Source, were used to quantify changes in the preferred orientation (crystallographic texture) within the labial regions of each tooth slice and then correlated with the local microstructure. In general, healthy deciduous incisors displayed a higher degree of crystal organization across the labial surface in comparison with the hypoplastic enamel. ENAM plays the greatest functional role at the enamel-dentine junction (EDJ), as it was the region that exhibited lowest texture relative to unaffected controls. Other areas within the tooth, however, such as the cusp tip, displayed greater organization in line with healthy enamel, suggesting its effects are restricted to the early stages of enamel secretion. Observed clinically, the surface of ENAM-mutated hypoplastic enamel can appear to be normal, yet severe sub-nano and microstructural defects appear beneath the subsurface layer. Quantitative characterization of the crystallographic properties from enamel with known genotype expands the understanding of enamel formation processes and can aid better clinical diagnosis and tailor-made treatment.
The Molecular Basis of Hereditary Enamel Defects in Humans
Carrion, I.A.; Morris, C.
2015-01-01
The formation of human enamel is highly regulated at the molecular level and involves thousands of genes. Requisites for development of this highly mineralized tissue include cell differentiation; production of a unique extracellular matrix; processing of the extracellular matrix; altering of cell function during different stages of enamel formation; cell movement and attachment; regulation of ion and protein movement; and regulation of hydration, pH, and other conditions of the microenvironment, to name just a few. Not surprising, there is a plethora of hereditary conditions with an enamel phenotype. The objective of this review was to identify the hereditary conditions listed on Online Mendelian Inheritance in Man (OMIM) that have an associated enamel phenotype and whether a causative gene has been identified. The OMIM database was searched with the terms amelogenesis, enamel, dental, and tooth, and all results were screened by 2 individuals to determine if an enamel phenotype was identified. Gene and gene product function was reviewed on OMIM and from publications identified in PubMed. The search strategy revealed 91 conditions listed in OMIM as having an enamel phenotype, and of those, 71 have a known molecular etiology or linked genetic loci. The purported protein function of those conditions with a known genetic basis included enzymes, regulatory proteins, extracellular matrix proteins, transcription factors, and transmembrane proteins. The most common enamel phenotype was a deficient amount of enamel, or enamel hypoplasia, with hypomineralization defects being reported less frequently. Knowing these molecular defects allows an initial cataloging of molecular pathways that lead to hereditary enamel defects in humans. This knowledge provides insight into the diverse molecular pathways involved in enamel formation and can be useful when searching for the genetic etiology of hereditary conditions that involve enamel. PMID:25389004
Biomimetic Enamel Regeneration Mediated by Leucine-Rich Amelogenin Peptide.
Kwak, S Y; Litman, A; Margolis, H C; Yamakoshi, Y; Simmer, J P
2017-01-01
We report here a novel biomimetic approach to the regeneration of human enamel. The approach combines the use of inorganic pyrophosphate (PPi) to control the onset and rate of enamel regeneration and the use of leucine-rich amelogenin peptide (LRAP), a nonphosphorylated 56-amino acid alternative splice product of amelogenin, to regulate the shape and orientation of growing enamel crystals. This study builds on our previous findings that show LRAP can effectively guide the formation of ordered arrays of needle-like hydroxyapatite (HA) crystals in vitro and on the known role mineralization inhibitors, like PPi, play in the regulation of mineralized tissue formation. Acid-etched enamel surfaces of extracted human molars, cut perpendicular or parallel to the direction of the enamel rods, were exposed to a PPi-stabilized supersaturated calcium phosphate (CaP) solution containing 0 to 0.06 mg/mL LRAP for 20 h. In the absence of LRAP, PPi inhibition was reversed by the presence of etched enamel surfaces and led to the formation of large, randomly distributed plate-like HA crystals that were weakly attached, regardless of rod orientation. In the presence of 0.04 mg/mL LRAP, however, densely packed mineral layers, comprising bundles of small needle-like HA crystals, formed on etched surfaces that were cut perpendicular to the enamel rods. These crystals were strongly attached, and their arrangement reflected to a significant degree the underlying enamel prism pattern. In contrast, under the same conditions with LRAP, little to no crystal formation was found on enamel surfaces that were cut parallel to the direction of the enamel rods. These results suggest that LRAP preferentially interacts with ab surfaces of mature enamel crystals, inhibiting their directional growth, thus selectively promoting linear growth along the c-axis of enamel crystals. The present findings demonstrate a potential for the development of a new approach to regenerate enamel structure and properties.
The molecular basis of hereditary enamel defects in humans.
Wright, J T; Carrion, I A; Morris, C
2015-01-01
The formation of human enamel is highly regulated at the molecular level and involves thousands of genes. Requisites for development of this highly mineralized tissue include cell differentiation; production of a unique extracellular matrix; processing of the extracellular matrix; altering of cell function during different stages of enamel formation; cell movement and attachment; regulation of ion and protein movement; and regulation of hydration, pH, and other conditions of the microenvironment, to name just a few. Not surprising, there is a plethora of hereditary conditions with an enamel phenotype. The objective of this review was to identify the hereditary conditions listed on Online Mendelian Inheritance in Man (OMIM) that have an associated enamel phenotype and whether a causative gene has been identified. The OMIM database was searched with the terms amelogenesis, enamel, dental, and tooth, and all results were screened by 2 individuals to determine if an enamel phenotype was identified. Gene and gene product function was reviewed on OMIM and from publications identified in PubMed. The search strategy revealed 91 conditions listed in OMIM as having an enamel phenotype, and of those, 71 have a known molecular etiology or linked genetic loci. The purported protein function of those conditions with a known genetic basis included enzymes, regulatory proteins, extracellular matrix proteins, transcription factors, and transmembrane proteins. The most common enamel phenotype was a deficient amount of enamel, or enamel hypoplasia, with hypomineralization defects being reported less frequently. Knowing these molecular defects allows an initial cataloging of molecular pathways that lead to hereditary enamel defects in humans. This knowledge provides insight into the diverse molecular pathways involved in enamel formation and can be useful when searching for the genetic etiology of hereditary conditions that involve enamel.
Enamel microstructure in Lemuridae (Mammalia, Primates): assessment of variability.
Maas, M C
1994-10-01
This study describes the molar enamel microstructure of seven lemurid primates: Hapalemur griseus, Varecia variegata, Lemur catta, Lemur macaco, Lemur fulvus rufus, Lemur fulvus fulvus, and Lemur fulvus albifrons. Contrary to earlier accounts, which reported little or no prism decussation in lemurid enamel, both Lemur and Varecia molars contain a prominent inner layer of decussating prisms (Hunter-Schreger bands), in addition to an outer radial prism layer, and a thin, nonprismatic enamel surface layer. In contrast, Hapalemur enamel consists entirely of radial and, near the surface, nonprismatic enamel. In addition, for all species, prism packing patterns differ according to depth from the tooth surface, and for all species but Varecia (which also has the thinnest enamel of any lemurid), average prism area increases from the enamel-dentine junction to the surface; this may be a developmental solution to the problem of accommodating a larger outer surface area with enamel deposited from a fixed number of cells. Finally, contradicting some previous reports, Pattern 1 prisms predominate only in the most superficial prismatic enamel. In the deeper enamel, prism cross-sections include both closed (Pattern 1) and arc-shaped (Pattern 2 or, most commonly, Pattern 3). This sequence of depth-related pattern change is repeated in all taxa. It should also be emphasized that all taxa can exhibit all three prism patterns in their mature enamel. The high degree of quantitative and qualitative variation in prism size, shape, and packing suggests that these features should be used cautiously in phylogenetic studies. Hapalemur is distinguished from the other lemurids by unique, medially constricted or rectangular prism cross-sections at an intermediate depth and the absence of prism decussation, but, without further assessment of character polarity, these differences do not clarify lemurid phylogenetic relations. Some characters of enamel microstructure may represent synapomorphies
Chee, Soon-Phaik
2011-09-01
A modified suture technique for precise knot placement in the Hoffman corneoscleral pocket technique of scleral fixation is described. Both loops of the polypropylene suture passing from the intraocular device through the sclera and conjunctiva are retrieved from the pocket. A loop of suture is pulled through 3 suture throws made using the second suture loop, forming a half bow. Centration of the intraocular lens (IOL)-capsular bag is checked. If the suture tension is too tight, the surgeon can easily undo the knot of the half-bow knot by pulling it free and can then retie the sliding knot. When the IOL-capsular bag is centered, the suture loop is cut and the free end removed. The second suture end is retrieved from the pocket, and knot tying is completed without further adjustment to the tension. Posterior pressure on the intraocular device centers it and settles the knot within the sclera at the fixation point.
Effect of fluoridated dentifrices on surface microhardness of the enamel of deciduous teeth
Seyed Ebrahim Jabbarifar
2011-01-01
Full Text Available Background: Surface microhardness is a physical property which access the effect of chemical and physical agents on hard tissues of teeth, and a useful way to examine the resistance of fluoride treated enamel against caries. The purpose of this study was to evaluate microhardness of enamel following pH-cycling through demineralization and remineralization using suspensions of dentifrices with different fluoride contents. Methods: In this in vitro study 56 enamel blocks of primary incisors were soaked in demineralizing solution and four dentifrices suspensions including: Crest 1100 ppm F (NaF, Crest 500 ppm F (NaF, Pooneh 500 ppm F (NaF, and Pooneh without fluoride. The means and percentage changes of surface microhardness in pre-demineralization, after demineralization and remineralization stages in four groups were measured. The findings of four groups in three stages were compared by, ANOVA, Tukey and paired t-tests. (α=0.05 Results: Average surface microhardness changes of Crest 1100 ppm F, was higher than Crest 500 ppm F, Pooneh 500 ppm F, and Pooneh without fluoride. The percentages of surface microhardness recovery for Crest 1100 ppm F, Crest 500 ppm F, Pooneh 500 ppm F, and Pooneh without fluoride were 45.4, 35.4, 28.6, and 23.7 respectively. Demineralization treatment decreased the surface microhardness of enamel (P<0.05 and the surface microhardness recovery in all groups were significant (P<0.0001. Conclusion: Surface microhardness of enamel after remineralization by Crest 1100 ppm F was higher than Crest 500 ppm F, Pooneh 500 ppm F, and Pooneh without fluoride.
Dental enamel defects, caries experience and oral health-related quality of life: a cohort study.
Arrow, P
2017-06-01
The impact of enamel defects of the first permanent molars on caries experience and child oral health-related quality of life was evaluated in a cohort study. Children who participated in a study of enamel defects of the first permanent molars 8 years earlier were invited for a follow-up assessment. Consenting children completed the Child Perception Questionnaire and the faces Modified Child Dental Anxiety Scale, and were examined by two calibrated examiners. ANOVA, Kruskal-Wallis, negative binomial and logistic regression were used for data analyses. One hundred and eleven children returned a completed questionnaire and 91 were clinically examined. Negative binomial regression found that oral health impacts were associated with gender (boys, risk ratio (RR) = 0.73, P = 0.03) and decayed, missing or filled permanent teeth (DMFT) (RR = 1.1, P = 0.04). The mean DMFT of children were sound (0.9, standard deviation (SD) = 1.4), diffuse defects (0.8, SD = 1.7), demarcated defects (1.5, SD = 1.4) and pit defects (1.3, SD = 2.3) (Kruskal-Wallis, P = 0.05). Logistic regression of first permanent molar caries found higher odds of caries experience with baseline primary tooth caries experience (odds ratio (OR) = 1.5, P = 0.01), the number of teeth affected by enamel defects (OR = 1.9, P = 0.05) and lower odds with the presence of diffuse enamel defects (OR = 0.1, P = 0.04). The presence of diffuse enamel defects was associated with lower odds of caries experience. © 2016 Australian Dental Association.
A steered molecular dynamics study on the elastic behaviour of knotted polymer chains
Shen Yu; Zhang Lin-Xi
2008-01-01
In this paper the influence of a knot on the structure of a polymethylene (PM) strand in the tensile process is investigated by using the steered molecular dynamics (SMD) method. The gradual increasing of end-to-end distance, R,results in a tighter knot and a more stretched contour. That the break in a knotted rope almost invariably occurs at a point just outside the 'entrance' to the knot, which has been shown in a good many experiments, is further theoretically verified in this paper through the calculation of some structural and thermodynamic parameters. Moreover, it is found that the analyses on bond length, torsion angle and strain energy can facilitate to the study of the localization and the size of a knot in the tensile process. The symmetries of torsion angles, bond lengths and bond angles in the knot result in the whole symmetry of the knot in microstructure, thereby adapting itself to the strain applied. Additionally,the statistical property of the force-dependent average knot size illuminates in detail the change in size of a knot with force f, and therefore the minimum size of the knot in the restriction of the potentials considered in this work for a PM chain is deduced. At the same time, the difference in response to uniaxial strain, between a knotted PM strand and an unknotted one is also investigated. The force-extension profile is easily obtained from the simulation. As expected,for a given f, the knotted chain has an R significantly smaller than that of an unknotted polymer. However, the scaled difference becomes less pronounced for larger values of N, and the results for longer chains approach those of the unknotted chains.
KNOT POINT PLANNING FOR CARTESIAN TRAJECTORY GENERATION BASED ON INHERITANCE BISECTION ALGORITHM
Yan Bo; Yan Guozheng
2005-01-01
The computation algorithm of knot point planning for Cartesian trajectory generation of manipulator is investigated. A novel inheritance bisection algorithm (IBA) based on conventional bisection algorithm (BA) is proposed. IBA has two steps. The first step is the 1st knot point planning under lower set position accuracy; the second step is the 2nd knot point planning that inherits the results of the 1st planning under higher set position accuracy. The simulation results reveal that the number of inverse kinematical calculation (IKC) caused by IBA is decreased compared with BA. IBA is more efficient to plan knot points.
Safavieh, Roozbeh; Zhou, Gina Z; Juncker, David
2011-08-07
We present and characterize cotton yarn and knots as building blocks for making microfluidic circuits from the bottom up. The yarn used is made up of 200-300 fibres, each with a lumen. Liquid applied at the extremity of the yarn spontaneously wets the yarn, and the wetted length increases linearly over time in untreated yarn, but progresses according to a square root relationship as described by Washburn's equation upon plasma activation of the yarn. Knots are proposed for combining, mixing and splitting streams of fluids. Interestingly, the topology of the knot controls the mixing ratio of two inlet streams into two outlet yarns, and thus the ratio can be adjusted by choosing a specific knot. The flow resistance of a knot is shown to depend on the force used to tighten it and the flow resistance rapidly increases for single-stranded knots, but remains low for double-stranded knots. Finally, a serial dilutor is made with a web made of yarns and double-stranded overhand knots. These results suggest that yarn and knots may be used to build low cost microfluidic circuits.
Amelogenin evolution and tetrapod enamel structure.
Diekwisch, Thomas G H; Jin, Tianquan; Wang, Xinping; Ito, Yoshihiro; Schmidt, Marcella; Druzinsky, Robert; Yamane, Akira; Luan, Xianghong
2009-01-01
Amelogenins are the major proteins involved in tooth enamel formation. In the present study, we have cloned and sequenced four novel amelogenins from three amphibian species in order to analyze similarities and differences between mammalian and non-mammalian amelogenins. The newly sequenced amphibian amelogenin sequences were from a red-eyed tree frog (Litoria chloris) and a Mexican axolotl (Ambystoma mexicanum). We identified two amelogenin isoforms in the Eastern red-backed salamander (Plethodon cinereus). Sequence comparisons confirmed that non-mammalian amelogenins are overall shorter than their mammalian counterparts, contain less proline and less glutamine, and feature shorter polyproline tripeptide repeat stretches than mammalian amelogenins. We propose that unique sequence parameters of mammalian amelogenins might be a pre-requisite for complex mammalian enamel prism architecture. Copyright (c) 2009 S. Karger AG, Basel.
Enamelin is critical for ameloblast integrity and enamel ultrastructure formation.
Jan C-C Hu
Full Text Available Mutations in the human enamelin gene cause autosomal dominant hypoplastic amelogenesis imperfecta in which the affected enamel is thin or absent. Study of enamelin knockout NLS-lacZ knockin mice revealed that mineralization along the distal membrane of ameloblast is deficient, resulting in no true enamel formation. To determine the function of enamelin during enamel formation, we characterized the developing teeth of the Enam-/- mice, generated amelogenin-driven enamelin transgenic mouse models, and then introduced enamelin transgenes into the Enam-/- mice to rescue enamel defects. Mice at specific stages of development were subjected to morphologic and structural analysis using β-galactosidase staining, immunohistochemistry, and transmission and scanning electron microscopy. Enamelin expression was ameloblast-specific. In the absence of enamelin, ameloblasts pathology became evident at the onset of the secretory stage. Although the aggregated ameloblasts generated matrix-containing amelogenin, they were not able to create a well-defined enamel space or produce normal enamel crystals. When enamelin is present at half of the normal quantity, enamel was thinner with enamel rods not as tightly arranged as in wild type suggesting that a specific quantity of enamelin is critical for normal enamel formation. Enamelin dosage effect was further demonstrated in transgenic mouse lines over expressing enamelin. Introducing enamelin transgene at various expression levels into the Enam-/- background did not fully recover enamel formation while a medium expresser in the Enam+/- background did. Too much or too little enamelin abolishes the production of enamel crystals and prism structure. Enamelin is essential for ameloblast integrity and enamel formation.
Enamelin Is Critical for Ameloblast Integrity and Enamel Ultrastructure Formation
Hu, Jan C.-C.; Hu, Yuanyuan; Lu, Yuhe; Smith, Charles E.; Lertlam, Rangsiyakorn; Wright, John Timothy; Suggs, Cynthia; McKee, Marc D.; Beniash, Elia; Kabir, M. Enamul; Simmer, James P.
2014-01-01
Mutations in the human enamelin gene cause autosomal dominant hypoplastic amelogenesis imperfecta in which the affected enamel is thin or absent. Study of enamelin knockout NLS-lacZ knockin mice revealed that mineralization along the distal membrane of ameloblast is deficient, resulting in no true enamel formation. To determine the function of enamelin during enamel formation, we characterized the developing teeth of the Enam−/− mice, generated amelogenin-driven enamelin transgenic mouse models, and then introduced enamelin transgenes into the Enam−/− mice to rescue enamel defects. Mice at specific stages of development were subjected to morphologic and structural analysis using β-galactosidase staining, immunohistochemistry, and transmission and scanning electron microscopy. Enamelin expression was ameloblast-specific. In the absence of enamelin, ameloblasts pathology became evident at the onset of the secretory stage. Although the aggregated ameloblasts generated matrix-containing amelogenin, they were not able to create a well-defined enamel space or produce normal enamel crystals. When enamelin is present at half of the normal quantity, enamel was thinner with enamel rods not as tightly arranged as in wild type suggesting that a specific quantity of enamelin is critical for normal enamel formation. Enamelin dosage effect was further demonstrated in transgenic mouse lines over expressing enamelin. Introducing enamelin transgene at various expression levels into the Enam−/− background did not fully recover enamel formation while a medium expresser in the Enam+/− background did. Too much or too little enamelin abolishes the production of enamel crystals and prism structure. Enamelin is essential for ameloblast integrity and enamel formation. PMID:24603688
Theobromine Effects on Enamel Surface Microhardness: In Vitro
Grace Syafira; Rina Permatasari; Nina Wardani
2013-01-01
Dental caries is still a dental health problem in Indonesia. Fluoride, one of the dental caries prevention material, but its safety and the danger of fluorosis is still debated. Theobromine is an alkaloid compound contained in cocoa beans. Theobromine is believed to increase enamel microhardness with mineral changes in the enamel superficial layer. Objectives: To determine the influence of theobromine on the enamel surface microhardness. Methods: This study used 40 premolar tooth crown pieces...
Laser Ultrasonic Technique for Evaluating Human Dental Enamel
Wang, D H-C; Fleming, S; Law, S [Insititue of Photonics and Optical Science, School of Physics, University of Sydney, NSW 2006 (Australia); Lee, Y-C [Department of Mechanical Engineering, National Cheng Kung University, Tainan City, Taiwan (China); Swain, M; Xue, J, E-mail: hsiao-chuan.wang@sydney.edu.au [Faculty of Dentistry, University of Sydney, NSW 2006 (Australia)
2011-01-01
A non-destructive laser ultrasonic surface acoustic wave technique has been demonstrated to quantitatively evaluate the elastic response of human dental enamel. We demonstrate the system performance by measuring surface acoustic wave velocity in sound and demineralised enamel. In addition, progressive measurements were made to monitor the change in the enamel elasticity during a two week remineralisation process. The results are presented and they confirm the efficacy, as well as illuminating the progress, of the treatment.
Sea otter dental enamel is highly resistant to chipping due to its microstructure
Ziscovici, Charles; Peter W. Lucas; Constantino, Paul J.; Timothy G. Bromage; van Casteren, Adam
2014-01-01
Dental enamel is prone to damage by chipping with large hard objects at forces that depend on chip size and enamel toughness. Experiments on modern human teeth have suggested that some ante-mortem chips on fossil hominin enamel were produced by bite forces near physiological maxima. Here, we show that equivalent chips in sea otter enamel require even higher forces than human enamel. Increased fracture resistance correlates with more intense enamel prism decussation, often seen also in some fo...
Controlled toothbrush abrasion of softened human enamel.
Voronets, J; Jaeggi, T; Buergin, W; Lussi, A
2008-01-01
The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17-39) nm]; (2) hard toothbrush only [25 (16-34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27-65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24-66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55-87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60-110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39-57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29-51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37-65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36-68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05). Copyright 2008 S. Karger AG, Basel.
Vitreous enamel coatings as porous composites
Chardakov, N.T.; Pychmintsev, I.Yu. [Science and Research Inst. for Materials and Technology, Ekaterinburg (Russian Federation); Kudyakov, V.Ya. [Inst. of High Temperature Electrochemistry, Ekaterinburg (Russian Federation)
2003-07-01
Recent investigations have shown, that vitreous enamel coatings can be considered as composite materials properties of which are determined more by macrostructure rather than microstructure. Detrimental effect of both the bubble structure and the presence of solid inclusions on such important properties as adhesion and protection potential in different corrosive environment was found. Typical microstructure parameters found experimentally were applied for analytical macrostructure-properties relationships. (author)
Region-dependent micro damage of enamel under indentation
Bing-Bing An; Rao-Rao Wang; Dong-Sheng Zhang
2012-01-01
The objective of this investigation is to explore the region-dependent damage behavior of enamel,as well as to develop a good understanding of the deformation mechanisms of enamel with numerical modeling.Nanoindentation experiments have been performed to investigate the load-penetration depth responses for outer and inner enamel.Results show that the unloading curve does not follow the loading curve,and degradation of stiffness in the unloading curve is observed.Based on the experimental data,a physical quantity,the chain density in protein,has been introduced to the Drucker-Prager plastic model.Numerical simulations show that the simulated load-penetration depth curves agree with the experiments,and the stiffness degradation behaviors of outer and inner enamel are captured by the numerical model.The region-dependent damage behavior of enamel could be revealed by the numerical model.The micro damage affected area at inner enamel is larger than that at outer enamel,indicating that the inner enamel experiences more micro damage than the outer one.Compared with its outer counterpart,the inner enamel which is rich in organic protein could break more internal protein chains to dissipate energy and to enhance its resistance to fracture accordingly.
Hair keratin mutations in tooth enamel increase dental decay risk.
Duverger, Olivier; Ohara, Takahiro; Shaffer, John R; Donahue, Danielle; Zerfas, Patricia; Dullnig, Andrew; Crecelius, Christopher; Beniash, Elia; Marazita, Mary L; Morasso, Maria I
2014-12-01
Tooth enamel is the hardest substance in the human body and has a unique combination of hardness and fracture toughness that protects teeth from dental caries, the most common chronic disease worldwide. In addition to a high mineral content, tooth enamel comprises organic material that is important for mechanical performance and influences the initiation and progression of caries; however, the protein composition of tooth enamel has not been fully characterized. Here, we determined that epithelial hair keratins, which are crucial for maintaining the integrity of the sheaths that support the hair shaft, are expressed in the enamel organ and are essential organic components of mature enamel. Using genetic and intraoral examination data from 386 children and 706 adults, we found that individuals harboring known hair disorder-associated polymorphisms in the gene encoding keratin 75 (KRT75), KRT75(A161T) and KRT75(E337K), are prone to increased dental caries. Analysis of teeth from individuals carrying the KRT75(A161T) variant revealed an altered enamel structure and a marked reduction of enamel hardness, suggesting that a functional keratin network is required for the mechanical stability of tooth enamel. Taken together, our results identify a genetic locus that influences enamel structure and establish a connection between hair disorders and susceptibility to dental caries.
Influence of trace elements on dental enamel properties: A review.
Qamar, Zeeshan; Haji Abdul Rahim, Zubaidah Binti; Chew, Hooi Pin; Fatima, Tayyaba
2017-01-01
Dental enamel, an avascular, irreparable, outermost and protective layer of the human clinical crown has a potential to withstand the physico-chemical effects and forces. These properties are being regulated by a unique association among elements occurring in the crystallites setup of human dental enamel. Calcium and phosphate are the major components (hydroxyapatite) in addition to some trace elements which have a profound effect on enamel. The current review was planned to determine the aptitude of various trace elements to substitute and their influence on human dental enamel in terms of physical and chemical properties.
Spectrophotometric comparison of translucent composites and natural enamel.
Li, Q; Xu, B T; Li, R; Wang, Y N
2010-01-01
To compare the optical characters of four translucent composites and natural enamel. Thirty natural enamel slabs and 120 composite replicas (n=30) using four brands of translucent composites (Polofil Supra, Brilliant Esthetic, Gradia Direct, and Vit-l-escence) were evaluated at the thicknesses of 1.0mm and 0.8mm. The colors of the enamel slabs or corresponding composite specimens placed on an A3 shade, white and black backgrounds were measured using a spectrophotometer. Color differences (ΔE*) of the enamel-composite pairs and translucency parameter (TP) of each specimen were calculated. Reflection spectrums were recorded in the wavelength from 380nm to 780nm. Paired-t tests were performed to evaluate the differences of color coordinates (L*, a*, and b*) and TP values between the translucent composites and natural enamel. There were significant differences of color coordinates (L*, a*, and b*) between the enamel and translucent composites (Pcomposite pairs with Polofil Supra and Brilliant Esthetic composites. The main peaks of the reflectance spectrums of the enamel are different from the four brands of the translucent composites. A reddish shifting of the main reflection peaks was observed, while the thickness of the composite specimens decreasing from 1.0mm to 0.8mm. Whereas, the main reflection peak was not changed in the teeth enamel. The color and the translucency of translucent composites are different from the teeth enamel. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.
Enamel Pearls Implications on Periodontal Disease
Elton Gonçalves Zenóbio
2015-01-01
Full Text Available Dental anatomy is quite complex and diverse factors must be taken into account in its analysis. Teeth with anatomical variations present an increase in the rate of severity periodontal tissue destruction and therefore a higher risk of developing periodontal disease. In this context, this paper reviews the literature regarding enamel pearls and their implications in the development of severe localized periodontal disease as well as in the prognosis of periodontal therapy. Radiographic examination of a patient complaining of pain in the right side of the mandible revealed the presence of a radiopaque structure around the cervical region of lower right first premolar. Periodontal examination revealed extensive bone loss since probing depths ranged from 7.0 mm to 9.0 mm and additionally intense bleeding and suppuration. Surgical exploration detected the presence of an enamel pearl, which was removed. Assessment of the remaining supporting tissues led to the extraction of tooth 44. Local factors such as enamel pearls can lead to inadequate removal of the subgingival biofilm, thus favoring the establishment and progression of periodontal diseases.
Enamel Pearls Implications on Periodontal Disease
Zenóbio, Elton Gonçalves; Vieira, Thaís Ribeiral; Bustamante, Roberta Paula Colen; Gomes, Hayder Egg; Shibli, Jamil Awad; Soares, Rodrigo Villamarin
2015-01-01
Dental anatomy is quite complex and diverse factors must be taken into account in its analysis. Teeth with anatomical variations present an increase in the rate of severity periodontal tissue destruction and therefore a higher risk of developing periodontal disease. In this context, this paper reviews the literature regarding enamel pearls and their implications in the development of severe localized periodontal disease as well as in the prognosis of periodontal therapy. Radiographic examination of a patient complaining of pain in the right side of the mandible revealed the presence of a radiopaque structure around the cervical region of lower right first premolar. Periodontal examination revealed extensive bone loss since probing depths ranged from 7.0 mm to 9.0 mm and additionally intense bleeding and suppuration. Surgical exploration detected the presence of an enamel pearl, which was removed. Assessment of the remaining supporting tissues led to the extraction of tooth 44. Local factors such as enamel pearls can lead to inadequate removal of the subgingival biofilm, thus favoring the establishment and progression of periodontal diseases. PMID:26491574
Setally Azevedo Macena, Marcus; de Alencar e Silva Leite, Maria Luísa; de Lima Gouveia, Cíntia; de Lima, Tamires Alcoforado Sena; Athayde, Priscilla Alves Aguiar; de Sousa, Frederico Barbosa
2014-06-01
Dental enamel presents marked mechanical properties gradients from outer to inner enamel, a region lacking component volumes profiles. Tufts, structures of inner enamel, have been shown to play a role in enamel resilience. We aimed at comparing component volumes from inner to outer enamel in relation to enamel tufts. Transversal ground sections from the cervical half of unerupted human third molars (n=10) were prepared and histological points were selected along transversal lines (extending from innermost to outer enamel) traced across tufts and adjacent control areas without tufts. Component volumes were measured at each histological point. Component volumes ranges were: 70.6-98.5% (mineral), 0.02-20.78% (organic), 3.8-9.8% (total water), 3-9% (firmly bound water), and 0.02-3.3% (loosely bound water). Inner enamel presented the lowest mineral volumes and the highest non-mineral volumes. Mineral, water and organic contents differed as a function of the distance from innermost enamel but not between the tuft and control lines. Tufts presented opaqueness in polarizing microscopy (feature of fracture lines). Organic volume gradient correlated with a relatively flat profile of loosely bound water. Inner, but not outer enamel, rehydrated after air-dried enamel was heated to 50°C and re-exposed to room conditions, as predicted by the organic/water gradient profiles. Component volumes vary markedly from outer to inner enamel, but not between areas with or without tufts (that behave like fracture lines under polarizing microscopy). Copyright © 2014 Elsevier Ltd. All rights reserved.
Targeted p120-catenin ablation disrupts dental enamel development.
John D Bartlett
Full Text Available Dental enamel development occurs in stages. The ameloblast cell layer is adjacent to, and is responsible for, enamel formation. When rodent pre-ameloblasts become tall columnar secretory-stage ameloblasts, they secrete enamel matrix proteins, and the ameloblasts start moving in rows that slide by one another. This movement is necessary to form the characteristic decussating enamel prism pattern. Thus, a dynamic system of intercellular interactions is required for proper enamel development. Cadherins are components of the adherens junction (AJ, and they span the cell membrane to mediate attachment to adjacent cells. p120 stabilizes cadherins by preventing their internalization and degradation. So, we asked if p120-mediated cadherin stability is important for dental enamel formation. Targeted p120 ablation in the mouse enamel organ had a striking effect. Secretory stage ameloblasts detached from surrounding tissues, lost polarity, flattened, and ameloblast E- and N-cadherin expression became undetectable by immunostaining. The enamel itself was poorly mineralized and appeared to be composed of a thin layer of merged spheres that abraded from the tooth. Significantly, p120 mosaic mouse teeth were capable of forming normal enamel demonstrating that the enamel defects were not a secondary effect of p120 ablation. Surprisingly, blood-filled sinusoids developed in random locations around the developing teeth. This has not been observed in other p120-ablated tissues and may be due to altered p120-mediated cell signaling. These data reveal a critical role for p120 in tooth and dental enamel development and are consistent with p120 directing the attachment and detachment of the secretory stage ameloblasts as they move in rows.
Targeted p120-catenin ablation disrupts dental enamel development.
Bartlett, John D; Dobeck, Justine M; Tye, Coralee E; Perez-Moreno, Mirna; Stokes, Nicole; Reynolds, Albert B; Fuchs, Elaine; Skobe, Ziedonis
2010-09-16
Dental enamel development occurs in stages. The ameloblast cell layer is adjacent to, and is responsible for, enamel formation. When rodent pre-ameloblasts become tall columnar secretory-stage ameloblasts, they secrete enamel matrix proteins, and the ameloblasts start moving in rows that slide by one another. This movement is necessary to form the characteristic decussating enamel prism pattern. Thus, a dynamic system of intercellular interactions is required for proper enamel development. Cadherins are components of the adherens junction (AJ), and they span the cell membrane to mediate attachment to adjacent cells. p120 stabilizes cadherins by preventing their internalization and degradation. So, we asked if p120-mediated cadherin stability is important for dental enamel formation. Targeted p120 ablation in the mouse enamel organ had a striking effect. Secretory stage ameloblasts detached from surrounding tissues, lost polarity, flattened, and ameloblast E- and N-cadherin expression became undetectable by immunostaining. The enamel itself was poorly mineralized and appeared to be composed of a thin layer of merged spheres that abraded from the tooth. Significantly, p120 mosaic mouse teeth were capable of forming normal enamel demonstrating that the enamel defects were not a secondary effect of p120 ablation. Surprisingly, blood-filled sinusoids developed in random locations around the developing teeth. This has not been observed in other p120-ablated tissues and may be due to altered p120-mediated cell signaling. These data reveal a critical role for p120 in tooth and dental enamel development and are consistent with p120 directing the attachment and detachment of the secretory stage ameloblasts as they move in rows.
Racah matrices and hidden integrability in evolution of knots
Mironov, A.; Morozov, A.; Morozov, An.; Sleptsov, A.
2016-09-01
We construct a general procedure to extract the exclusive Racah matrices S and S bar from the inclusive 3-strand mixing matrices by the evolution method and apply it to the first simple representations R = [ 1 ], [2], [3] and [ 2 , 2 ]. The matrices S and S bar relate respectively the maps (R ⊗ R) ⊗ R bar ⟶ R with R ⊗ (R ⊗ R bar) ⟶ R and (R ⊗ R bar) ⊗ R ⟶ R with R ⊗ (R bar ⊗ R) ⟶ R. They are building blocks for the colored HOMFLY polynomials of arbitrary arborescent (double fat) knots. Remarkably, the calculation realizes an unexpected integrability property underlying the evolution matrices.
Knots and surfaces a guide to discovering mathematics
Farmer, David W
1995-01-01
In most mathematics textbooks, the most exciting part of mathematics-the process of invention and discovery-is completely hidden from the reader. The aim of Knots and Surfaces is to change all that. By means of a series of carefully selected tasks, this book leads readers to discover some real mathematics. There are no formulas to memorize; no procedures to follow. The book is a guide: its job is to start you in the right direction and to bring you back if you stray too far. Discovery is left to you. Suitable for a one-semester course at the beginning undergraduate level, there are no prerequi
Explorations in topology map coloring, surfaces and knots
Gay, David
2013-01-01
Explorations in Topology, Second Edition, provides students a rich experience with low-dimensional topology (map coloring, surfaces, and knots), enhances their geometrical and topological intuition, empowers them with new approaches to solving problems, and provides them with experiences that will help them make sense of future, more formal topology courses. The book's innovative story-line style models the problem-solving process, presents the development of concepts in a natural way, and engages students in meaningful encounters with the material. The updated end-of-chapter investigation
Punctured torus groups and 2-bridge knot groups
Akiyoshi, Hirotaka; Wada, Masaaki; Yamashita, Yasushi
2007-01-01
This monograph is Part 1 of a book project intended to give a full account of Jorgensen's theory of punctured torus Kleinian groups and its generalization, with application to knot theory. Although Jorgensen's original work was not published in complete form, it has been a source of inspiration. In particular, it has motivated and guided Thurston's revolutionary study of low-dimensional geometric topology. In this monograph, we give an elementary and self-contained description of Jorgensen's theory with a complete proof. Through various informative illustrations, readers are naturally led to an intuitive, synthetic grasp of the theory, which clarifies how a very simple fuchsian group evolves into complicated Kleinian groups.
Knotted Picture of a Quantum Network of Two Nodes
QIAN Shang-Wu; GU Zhi-Yu
2004-01-01
This article discusses the variation of the knotted picture of the quantum pure state |X〉 = α| ↑↓〉 + β|↓↑〉with the varintion of the complex coefficients a and β. It is shown that there are three kinds of link that correspond tc three different ranks of the matrix of covariance correlation tensor, i.e., the zero rank corresponds to trivial link, the rank one corresponds to the two-component link with two crossings, and the rank three corresponds to the two-component link with four crossings.
Design and performance of the APPLE-Knot undulator.
Ji, Fuhao; Chang, Rui; Zhou, Qiaogen; Zhang, Wei; Ye, Mao; Sasaki, Shigemi; Qiao, Shan
2015-07-01
Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.
孙晓玲; 王鹏; 曹玉梅; 刘树泰
2016-01-01
Objective To compare the enamel demineralization effect of different dairy (drink) goods for providing evidence for choosing children dairy (drink) products. Methods Immerse in vitro deciduous teeth in different dairy (drink) goods (milk powder solution group;yogurt group;fruit juice milk drinks group;distilled water group) for a week, the enamel surface ultrastructure in deciduous teeth immersed in different dairy (drink) were observed and compared by scanning electron microscope. Results Three kinds of dairy products (drink) can lead to deciduous teeth enamel surface microhardness decreased (P < 0.05). Different dairy products (drink) on isolated teeth enamel demineralization degree (F=20.14, P<0.05), juice milk drinks after immersion of the enamel surface microhardness of the lowest, followed by milk powder solution group and yogurt group. Deciduous teeth with three different dairy (drink) after 1 weeks of immer-sion, the enamel surface had different degree of demineralization phenomenon, observation showed irregular enamel sur-face morphology under scanning electron microscope, the phenomena of dissolution and removal of cracks, voids and so on, partial visible appearance or honeycomb pit. Conclusion Dairy (drink) product all can lead to a variety of deciduous teeth enamel demineralization of different level fruit juice milk drinks can cause serious demineralization.%目的：比较3种市售乳制（饮）品对离体乳牙牙釉质的脱矿作用，为儿童合理选择饮用乳制（饮）品提供依据。方法将离体乳牙浸泡在奶粉液（奶粉液组）、酸奶（酸奶组）、果汁型乳饮品（果汁型乳饮品组）、蒸馏水（蒸馏水组）等乳制（饮）品中1周，用扫描电镜观察并比较经不同乳制（饮）品浸泡后乳牙牙釉质表面超微结构的改变；用维氏显微硬度仪测定并比较乳牙牙釉质表面显微硬度的变化。结果3种乳制（饮）品均可导致离体乳牙牙釉质
Totally geodesic Seifert surfaces in hyperbolic knot and link complements II
Adams, Colin; Bennett, Hanna; Davis, Christopher James;
2008-01-01
We generalize the results of Adams–Schoenfeld, finding large classes of totally geodesic Seifert surfaces in hyperbolic knot and link complements, each covering a rigid 2-orbifold embedded in some hyperbolic 3-orbifold. In addition, we provide a uniqueness theorem and demonstrate that many knots ...
First report of the root-knot nematode Meloidogyne ethiopica on tomato in Slovenia
Sirca, S.; Urek, G.; Karssen, G.
2004-01-01
The root-knot nematode Meloidogyne ethiopica Whitehead originally described from Tanzania is also distributed in South Africa, Zimbabwe, and Ethiopia (3). Although this species is a relatively unknown root-knot nematode, M. ethiopica parasitizes several economical important crops, such as tomato, co
Repeat knot formation in a patient with an indwelling ureteral stent
Brian Eisner
2006-06-01
Full Text Available A patient treated for nephrolithiasis formed knots in 2 occasions, in 2 separate indwelling ureteral stents. This rare complication may make stent removal difficult. To our knowledge, this is the first case report of repeat knot formation in a single patient.
Totally geodesic Seifert surfaces in hyperbolic knot and link complements II
Adams, Colin; Bennett, Hanna; Davis, Christopher James
2008-01-01
We generalize the results of Adams–Schoenfeld, finding large classes of totally geodesic Seifert surfaces in hyperbolic knot and link complements, each covering a rigid 2-orbifold embedded in some hyperbolic 3-orbifold. In addition, we provide a uniqueness theorem and demonstrate that many knots...
Onrust, J.; de Fouw, J.; Oudman, T.; van der Geest, M.; Piersma, T.; van Gils, J.A.
2013-01-01
Capsule Context-specific equations are needed to reconstruct diet composition and intake rate of Red Knots by the use of shell fragments retrieved from droppings.Aims To explore whether the method to reconstruct Red Knot diet described by Dekinga & Piersma [Dekinga, A. & Piersma, T. 1993. Reconstruc
Onrust, Jeroen; De Fouw, Jimmy; Oudman, Thomas; Van der Geest, Matthijs; Piersma, Theunis; Van Gils, Jan A.
2013-01-01
Capsule Context-specific equations are needed to reconstruct diet composition and intake rate of Red Knots by the use of shell fragments retrieved from droppings. Aims To explore whether the method to reconstruct Red Knot diet described by Dekinga & Piersma [Dekinga, A. & Piersma, T. 1993. Reconstru
Why do few Afro-Siberian Knots Calidris canutus canutus now visit Britain?
Boyd, H; Piersma, T
2001-01-01
The nominate (Afro-Siberian) subspecies of the Knot Calidris canutus canutus breeds on the Taimyr Peninsula in Siberia and occurs commonly in the westernmost Wadden Sea during migration to West and South Africa. The recoveries and controls of 2045 Knots ringed in Britain and Ireland provide no evide
Expression of almond KNOTTED1 homologue (PdKn1) anticipates adventitious shoot initiation
Background and Aims: The transcription factor encoded by the gene Knotted1 is a nuclear homeodomain protein, regulating meristematic cells at the shoot apical meristem. It has been proven that Knotted1 (KN1) has a role in the switch from an indeterminate to determinate cell fate and as such this gen...
Verboven, N.; Piersma, T.
1995-01-01
To test whether Knot Calidris canutus wintering in the tropics suffer higher rates of water loss through evaporation than do Knot wintering at temperate latitudes, we tried to develop a physically realistic model to predict evaporative heat loss from air temperature, wind and humidity. In separate e
Knot Physics -- an Ultimate Unified Theory of Matter and its Motion
Kou, Su-Peng
2016-01-01
A Theory of Everything (TOE) is physics theory that unifies all the fundamental interactions of nature: gravitation, strong interaction, weak interaction, and electromagnetism.\\ Now, TOE becomes the Holy Grail of modern physics. In this paper, knot physics becomes a new candidate of TOE that not only unified all the fundamental interactions but also explores the underline physics of quantum mechanics. In knot physics, our universe is a standard knot-crystal, a particular periodic entanglement-pattern between two 3-branes (three dimensional branes/manifolds), of which the low energy effective theory not only reproduces the Standard model -- an SU(3)*SU(2)*U(1) gauge theory but also leads to the physics of general relativity. The collective motions of the standard knot-crystal are described by fermionic elementary particles and gauge fields. Fermionic elementary particles are topological excitations that correspond to different types of knots.
Dental enamel defects in children with coeliac disease
Wierink, C.D.; van Diermen, D.E.; Aartman, I.H.A.; Heijmans, H.S.A.
2007-01-01
Objective. The aim of this study was to investigate whether Dutch children with proven coeliac disease show specific dental enamel defects, and to asses whether children with the same gastrointestinal complaints, but proved no-coeliac disease, lack these specific dental enamel defects. Materials and
Conservative approach for esthetic treatment of enamel hypoplasia.
Reston, E G; Corba, D V; Ruschel, K; Tovo, M F; Barbosa, A N
2011-01-01
This article describes a minimally invasive technique for removal of intrinsic enamel stains and discoloration. The technique is based on enamel microabrasion with application of an acid-abrasive gel. Treatment may be complemented with composite resin to compensate for the effects of acid or to finish the masking effect.
Exaggerated abrasion/erosion of human dental enamel surfaces
Westergaard, J; Moe, D; Pallesen, Ulla
1993-01-01
An atypical, rapidly proceeding abrasion/erosion of the labial enamel surfaces of the maxillary and mandibular incisors and canines in a 27-yr-old man is reported. Ultrastructural examination of a replica of the teeth showed a practically structureless enamel surface both at the initial examinati...
Targeted overexpression of amelotin disrupts the microstructure of dental enamel.
Rodrigo S Lacruz
Full Text Available We have previously identified amelotin (AMTN as a novel protein expressed predominantly during the late stages of dental enamel formation, but its role during amelogenesis remains to be determined. In this study we generated transgenic mice that produce AMTN under the amelogenin (Amel gene promoter to study the effect of AMTN overexpression on enamel formation in vivo. The specific overexpression of AMTN in secretory stage ameloblasts was confirmed by Western blot and immunohistochemistry. The gross histological appearance of ameloblasts or supporting cellular structures as well as the expression of the enamel proteins amelogenin (AMEL and ameloblastin (AMBN was not altered by AMTN overexpression, suggesting that protein production, processing and secretion occurred normally in transgenic mice. The expression of Odontogenic, Ameloblast-Associated (ODAM was slightly increased in secretory stage ameloblasts of transgenic animals. The enamel in AMTN-overexpressing mice was much thinner and displayed a highly irregular surface structure compared to wild type littermates. Teeth of transgenic animals underwent rapid attrition due to the brittleness of the enamel layer. The microstructure of enamel, normally a highly ordered arrangement of hydroxyapatite crystals, was completely disorganized. Tomes' process, the hallmark of secretory stage ameloblasts, did not form in transgenic mice. Collectively our data demonstrate that the overexpression of amelotin has a profound effect on enamel structure by disrupting the formation of Tomes' process and the orderly growth of enamel prisms.
A natural functionally graded biocomposite coating--human enamel.
He, Li-Hong; Yin, Zi-Hong; van Vuuren, Ludwig Jansen; Carter, Elizabeth A; Liang, Xiu-Weng
2013-05-01
Human enamel has been found to be a coating with excellent mechanical performance, and has undergone extensive investigation and discussion. However, most of the reported studies consider the enamel as a homogeneous anisotropic biocomposite. The current study illustrated the graded properties of the biocomposite from its functional load-bearing direction. Within the thickness of the enamel, from the outer surface towards the enamel-dentin junction (EDJ), the elastic modulus (E(x)) and hardness (H(x)) of enamel exist in an exponential relationship with normalized thickness (x) as E(x)=111.64x(0.18) (R(2)=0.94) and H(x)=4.41x(0.16) (R(2)=0.87) GPa, respectively. Moreover, the creep ability of enamel increases towards the EDJ. The graded properties of the biocomposite can be explained by both microstructural and compositional changes along the thickness of the material towards the EDJ. Finite element analysis indicates that the graded properties of enamel have important roles in reducing the enamel-dentin interface stresses and maintaining the integrity of the multilayer tooth structure. The results provide a new angle to understand the excellent mechanical behaviour of the multilayer tooth structure and may inspire the development of new functionally graded materials and coating structures.
Targeted overexpression of amelotin disrupts the microstructure of dental enamel.
Lacruz, Rodrigo S; Nakayama, Yohei; Holcroft, James; Nguyen, Van; Somogyi-Ganss, Eszter; Snead, Malcolm L; White, Shane N; Paine, Michael L; Ganss, Bernhard
2012-01-01
We have previously identified amelotin (AMTN) as a novel protein expressed predominantly during the late stages of dental enamel formation, but its role during amelogenesis remains to be determined. In this study we generated transgenic mice that produce AMTN under the amelogenin (Amel) gene promoter to study the effect of AMTN overexpression on enamel formation in vivo. The specific overexpression of AMTN in secretory stage ameloblasts was confirmed by Western blot and immunohistochemistry. The gross histological appearance of ameloblasts or supporting cellular structures as well as the expression of the enamel proteins amelogenin (AMEL) and ameloblastin (AMBN) was not altered by AMTN overexpression, suggesting that protein production, processing and secretion occurred normally in transgenic mice. The expression of Odontogenic, Ameloblast-Associated (ODAM) was slightly increased in secretory stage ameloblasts of transgenic animals. The enamel in AMTN-overexpressing mice was much thinner and displayed a highly irregular surface structure compared to wild type littermates. Teeth of transgenic animals underwent rapid attrition due to the brittleness of the enamel layer. The microstructure of enamel, normally a highly ordered arrangement of hydroxyapatite crystals, was completely disorganized. Tomes' process, the hallmark of secretory stage ameloblasts, did not form in transgenic mice. Collectively our data demonstrate that the overexpression of amelotin has a profound effect on enamel structure by disrupting the formation of Tomes' process and the orderly growth of enamel prisms.
Enameled Porcelain Bottle with Coral-Red Background
1998-01-01
Decorative enameled porcelain was used by the imperial court during the reigns of Kangxi, Yongzheng and Qianlong of the Qing Dynasty. It was a new kind of art which blended French enameling skills with Chinese traditional porcelain craftsmanship. First made in the reign of Kangxi, the porcelainware decorated with the
New genomic and fossil data illuminate the origin of enamel.
Qu, Qingming; Haitina, Tatjana; Zhu, Min; Ahlberg, Per Erik
2015-10-01
Enamel, the hardest vertebrate tissue, covers the teeth of almost all sarcopterygians (lobe-finned bony fishes and tetrapods) as well as the scales and dermal bones of many fossil lobe-fins. Enamel deposition requires an organic matrix containing the unique enamel matrix proteins (EMPs) amelogenin (AMEL), enamelin (ENAM) and ameloblastin (AMBN). Chondrichthyans (cartilaginous fishes) lack both enamel and EMP genes. Many fossil and a few living non-teleost actinopterygians (ray-finned bony fishes) such as the gar, Lepisosteus, have scales and dermal bones covered with a proposed enamel homologue called ganoine. However, no gene or transcript data for EMPs have been described from actinopterygians. Here we show that Psarolepis romeri, a bony fish from the the Early Devonian period, combines enamel-covered dermal odontodes on scales and skull bones with teeth of naked dentine, and that Lepisosteus oculatus (the spotted gar) has enam and ambn genes that are expressed in the skin, probably associated with ganoine formation. The genetic evidence strengthens the hypothesis that ganoine is homologous with enamel. The fossil evidence, further supported by the Silurian bony fish Andreolepis, which has enamel-covered scales but teeth and odontodes on its dermal bones made of naked dentine, indicates that this tissue originated on the dermal skeleton, probably on the scales. It subsequently underwent heterotopic expansion across two highly conserved patterning boundaries (scales/head-shoulder and dermal/oral) within the odontode skeleton.
Optical coherence tomography use in the diagnosis of enamel defects
Al-Azri, Khalifa; Melita, Lucia N.; Strange, Adam P.; Festy, Frederic; Al-Jawad, Maisoon; Cook, Richard; Parekh, Susan; Bozec, Laurent
2016-03-01
Molar incisor hypomineralization (MIH) affects the permanent incisors and molars, whose undermineralized matrix is evidenced by lesions ranging from white to yellow/brown opacities to crumbling enamel lesions incapable of withstanding normal occlusal forces and function. Diagnosing the condition involves clinical and radiographic examination of these teeth, with known limitations in determining the depth extent of the enamel defects in particular. Optical coherence tomography (OCT) is an emerging hard and soft tissue imaging technique, which was investigated as a new potential diagnostic method in dentistry. A comparison between the diagnostic potential of the conventional methods and OCT was conducted. Compared to conventional imaging methods, OCT gave more information on the structure of the enamel defects as well as the depth extent of the defects into the enamel structure. Different types of enamel defects were compared, each type presenting a unique identifiable pattern when imaged using OCT. Additionally, advanced methods of OCT image analysis including backscattered light intensity profile analysis and enface reconstruction were performed. Both methods confirmed the potential of OCT in enamel defects diagnosis. In conclusion, OCT imaging enabled the identification of the type of enamel defect and the determination of the extent of the enamel defects in MIH with the advantage of being a radiation free diagnostic technique.
Knots on a Torus: A Model of the Elementary Particles
Jack S. Avrin
2012-02-01
Full Text Available Two knots; just two rudimentary knots, the unknot and the trefoil. That’s all we need to build a model of the elementary particles of physics, one with fermions and bosons, hadrons and leptons, interactions weak and strong and the attributes of spin, isospin, mass, charge, CPT invariance and more. There are no quarks to provide fractional charge, no gluons to sequester them within nucleons and no “colors” to avoid violating Pauli’s principle. Nor do we require the importation of an enigmatic Higgs boson to confer mass upon the particles of our world. All the requisite attributes emerge simply (and relativistically invariant as a result of particle conformation and occupation in and of spacetime itself, a spacetime endowed with the imprimature of general relativity. Also emerging are some novel tools for systemizing the particle taxonomy as governed by the gauge group SU(2 and the details of particle degeneracy as well as connections to Hopf algebra, Dirac theory, string theory, topological quantum field theory and dark matter. One exception: it is found necessary to invoke the munificent geometry of the icosahedron in order to provide, as per the group “flavor” SU(3, a scaffold upon which to organize the well-known three generations—no more, no less—of the particle family tree.
A Knot Model Sugugested by the Standard Electroweak Theory
Finkelstein, R J
2004-01-01
We attempt to go beyond the standard electroweak theory by replacing the underlying Lie algebra with its q-deformation: SU_q(2) x SU(1). This step introduces new degrees of freedom that we interpret as indicative of non-locality and as a possible basis for a solitonic model of the elementary particles. The solitons are conjectured to be knotted flux tubes labelled by the irreducible representations of SU_q(2), an algebra which is not only closely related to the standard theory but also plays a role in the description of knots. Each of the four families of elementary fermions is conujectured to be represented by one of the four possible trefoils. The three individual fermions belonging to any family then occupy the three lowest states in the excitation spectrum of the trefoil for that family. The dimensionless deformation parameter, q, is assumed to be a function of the Higgs field and to be an effective measure of the influence of the new degrees of freedom introduced by the deformation of SU(2). One finds a ...
Kimura, Richard H.; Teed, Robert; Hackel, Benjamin J.; Pysz, Marybeth A.; Chuang, Courtney Z.; Sathirachinda, Ataya; Willmann, Jürgen K.; Gambhir, Sanjiv S.
2012-01-01
Purpose Detection of pancreatic cancer remains high priority and effective diagnostic tools are needed for clinical applications. Many cancer cells overexpress integrin αvβ6, a cell surface receptor being evaluated as a novel clinical biomarker. Experimental Design To validate this molecular target, several highly stable cystine knot peptides were engineered by directed evolution to bind specifically and with high-affinity (3-6 nM) to integrin αvβ6. The binders don’t cross-react with related integrin αvβ5, integrin α5β1 or tumor-angiogenesis associated integrin, αvβ3. Results Positron emission tomography showed that these disulfide-stabilized peptides rapidly accumulate at tumors expressing integrin αvβ6. Clinically relevant tumor-to-muscle ratios of 7.7 ± 2.4 to 11.3 ± 3.0 were achieved within one hour after radiotracer injection. Minimization of off-target dosing was achieved by reformatting αvβ6-binding activities across various natural and pharmacokinetically-stabilized cystine knot scaffolds with different amino acid content. We demonstrate that a peptide scaffold’s primary sequence directs its pharmacokinetics. Scaffolds with high arginine or glutamic acid content suffered high renal retention of > 75 percent injected dose per gram (%ID/g). Substitution of these amino acids with renally-cleared amino acids, notably serine, led to significant decreases in renal accumulation of < 20 %ID/g 1h post injection (p < 0.05, n=3). Conclusions We have engineered highly stable cystine knot peptides with potent and specific integrin αvβ6 binding activities for cancer detection. Pharmacokinetic engineering of scaffold primary sequence led to significant decreases in off-target radiotracer accumulation. Optimization of binding affinity, specificity, stability and pharmacokinetics will facilitate translation of cystine knots for cancer molecular imaging. PMID:22173551
Prevalence and possible etiology of dental enamel hypoplasia.
El-Najjar, M Y; DeSanti, M V; Ozebek, L
1978-02-01
Two hundred black and white adult human skeletons and 200 living black and white children from the greater Cleveland area were examined for evidence of enamel hypoplasia. Enamel hypoplasia, present in varying expressings (pits, lines and grooves), was found to be more prevalent in both skeletal samples, than in the living groups. In the majority of cases, sex differences between white and black males and females through time and space are highly significant for all tooth catagories. Regardless of the mechanisms behind it, prevalence of enamel hypoplasia for both white and black group has significantly declined through time. No evidence suggesting specific etiologies responsible for enamel hypoplasia can be found. In the majority of previously published reports, the etiology is still idiopathic. The reduction in the prevalence of enamel hypoplasia in the groups examined through time may be related to improved nutritional conditions and the elimination or decline of childhood diseases that have been implicated in this condition.
Enamel roughness and depth profile after phosphoric acid etching of healthy and fluorotic enamel.
Torres-Gallegos, I; Zavala-Alonso, V; Patiño-Marín, N; Martinez-Castañon, G A; Anusavice, K; Loyola-Rodríguez, J P
2012-06-01
Dental fluorosis requires aesthetic treatment to improve appearance and etching of enamel surfaces with phosphoric acid is a key step for adhesive restorations. The aim of this study was to evaluate surface roughness and a depth profile in healthy and fluorotic enamel before and after phosphoric acid etching at 15, 30 and 60 seconds. One hundred and sixty enamel samples from third molars with no fluorosis to severe fluorosis were evaluated by atomic force microscopy. Healthy enamel showed a statistically significant difference (p < 0.05) between mean surface roughness at 15 seconds (180.3 nm), 30 seconds (260.9 nm) and 60 seconds (346.5 nm); depth profiles revealed a significant difference for the 60 second treatment (4240.2 nm). For mild fluorosis, there was a statistically significant difference (p < 0.05) between mean surface roughness for 30 second (307.8 nm) and 60 second (346.6 nm) treatments; differences in depth profiles were statistically significant at 15 seconds (2546.7 nm), 30 seconds (3884.2 nm) and 60 seconds (3612.1 nm). For moderate fluorosis, a statistically significant difference (p < 0.05) was observed for surface roughness for 30 second (324.5 nm) and 60 second (396.6 nm) treatments. Surface roughness and depth profile analyses revealed that the best etching results were obtained at 15 seconds for the no fluorosis and mild fluorosis groups, and at 30 seconds for the moderate fluorosis group. Increasing the etching time for severe fluorosis decreased surface roughness and the depth profile, which suggests less micromechanical enamel retention for adhesive bonding applications. © 2012 Australian Dental Association.
Gold Enamel Choumps – A Case report
Sargam D. Kotecha
2016-09-01
Full Text Available Tooth jewellery has been practiced since time immemorial and has become an increasingly popular trend. This case report provides a brief insight into a kind of tooth adornment/a tooth tattoo on the enamel prevalent in parts of western Uttar Pradesh, India locally known as a ‘Choump’. A tooth tattooed with ‘Choumps’ has extremely low incidence and could be used as an identification trait. Tooth adornment with ‘Choumps’ has been reported in adults however, this is the first reported case of ‘Choumps’ in children.
Porcelain enamel passive thermal control coatings
Leggett, H.; King, H. M.
1978-01-01
This paper discusses the development and evaluation of a highly adherent, low solar absorptance, porcelain enamel thermal control coating applied to 6061 and 1100 aluminum for space vehicle use. The coating consists of a low index of refraction, transparent host frit and a high volume fraction of titania as rutile, crystallized in-situ, as the scattering medium. Solar absorptance is 0.21 at a coating thickness of 0.013 cm. Hemispherical emittance is 0.88. The change in solar absorptance is 0.03, as measured in-situ, after an exposure of 1000 equivalent sun hours in vacuum.
Shear strength of composite bonded to Er:YAG laser-prepared enamel: an in vitro comparative study.
Yung, Frank Y W; Gutknecht, Norbert; Franzen, Rene; Fischer, Horst
2013-05-01
The primary objective of this study is to investigate the adhesion properties between four current generations of bonding systems and enamel surface conditioned by Er:YAG laser, using an energy density comparable to the ablation threshold of enamel. By including an energy density comparable to published adhesion studies, the secondary objective is to compare the adhesion effects of these selected laser conditioning parameters on enamel with other similar published studies. Buccal sides of randomly selected human molars (N=117) were prepared and divided into nine experimental groups depending on the generations of bonding system represented by the corresponding number (G4, G5, G6, G7) and the additional laser conditioning on the enamel surface represented by laser etch (LE) and laser etch with a higher pulse energy, followed by acid etch (AE), if required. The bonding resin systems and their specific requirements were applied after the enamel surfaces were laser conditioned following a specific set of laser parameters. Composite posts of 1.6 mm in diameter and approximately 6 mm in length were then restored on each of the sample surfaces. After 48 h, the composite assemblies were tested to failure under compression using a knife edge loading head at a cross head speed of 1 mm/min until the composite cylinders were separated from the surface. The data collected were then analyzed using one-way analysis of variance and SAS software program (9.1, TS1M3). No significant difference was found among these groups: AE+G4/LEAE+G4, G6/LE+G6, and G7/LE+G7. Significant differences were found in the remaining groups: AE+G5/LEAE+G5, AE+G5/LEAE-H+G5, and LEAE+G5/LEAE-H+G5. The bond strength results were compared among similar published data and possible influences from different laser parameters, bonding systems, and their combined impact on the enamel surface and its adhesion properties were analyzed. Under our specific settings, additional laser conditioning after phosphoric acid
Chen, Yueli; Otis, Linda; Piao, Daqing; Zhu, Quing
2005-04-01
Enamel and dentin are the primary components of human teeth. Both of them have a strong polarization effect. We designed a polarization-sensitive optical coherence tomography (PSOCT) system to study the spatially resolved scattering and polarization phenomena of teeth. The system is constructed in free space to avoid the complexity of polarization control in fiber-based PSOCT. The structural features of enamel were evaluated in five human teeth that had no visible evidence of caries. The teeth were subsequently sectioned in mesial distal orientation and coronal orientation. Then the structural aspects of dentin were evaluated. OCT images were made of the mantel dentin near the dentin-enamel junction. Five teeth with interproximal and occlusal caries were also studied. With two channel and phase-retardation images, PSOCT provided better functional contrast and more detailed structural information than conventional OCT. For a better description of the measured PSOCT data, we classify these features by two types, i.e., the local textural features and the global structural features. This study indicates that PSOCT has the potential to be a powerful tool for research of dental formation and caries diagnosis.
Yasini E.
2005-05-01
Full Text Available Statement of Problem: The use of dentine bondings on enamel and dentin in total etch protocols has recently become popular. Unfilled resin is hydrophobic and dentin bonding is hydrophilic in nature. This chemical difference could be effective in enamel bonding process. Purpose: The aim of this study was to compare the shear bond strength of unfilled resin to dry enamel and dentin bonding to dry and moist enamel. Materials and Methods: In this experimental study, a total of 30 incisor teeth were used. The specimens were randomly assigned to three groups of 10. 37% phosphoric acid etchant was applied to the enamel surfaces in each group for 15 seconds, rinsed with water for 20 seconds and dried for 20 seconds with compressed air in groups one and two. After conditioning, group 1 received unfilled resin (Margin Bond, Colten and group 2 received dentin bonding (Single Bond, 3M and in group 3 after conditioning and rinsing with water, a layer of dentin bonding (Single Bond was applied on wet enamel. The enamel and dentin bonding were light cured for 20 seconds. A ring mold 3.5 mm in diameter and 2 mm height was placed over the specimens to receive the composite filling material (Z100, 3M. The composite was cured for 40 seconds. The specimens were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. The findings were analyzed by ANOVA One-Way and Tukey HSD tests. Results: Shear bond strength of dentin bonding to dry enamel was significantly less than unfilled resin to dry enamel (P<0.05. There was no significant difference between the bond strength of dentin bonding to moist and dry enamel. In addition bond strength of dentin bonding to wet enamel was not significantly different from unfilled resin to dry enamel. Conclusion: Based on the findings of this study, it is suggested that enamel surface should remain slightly moist after etching before bonding with single bond but when using unfilled resin, the
Sea otter dental enamel is highly resistant to chipping due to its microstructure.
Ziscovici, Charles; Lucas, Peter W; Constantino, Paul J; Bromage, Timothy G; van Casteren, Adam
2014-10-01
Dental enamel is prone to damage by chipping with large hard objects at forces that depend on chip size and enamel toughness. Experiments on modern human teeth have suggested that some ante-mortem chips on fossil hominin enamel were produced by bite forces near physiological maxima. Here, we show that equivalent chips in sea otter enamel require even higher forces than human enamel. Increased fracture resistance correlates with more intense enamel prism decussation, often seen also in some fossil hominins. It is possible therefore that enamel chips in such hominins may have formed at even greater forces than currently envisaged.
Toothpaste Prevents Debonded Brackets on Erosive Enamel
Érico Luiz Damasceno Barros
2015-01-01
Full Text Available This study evaluated the effect of high fluoride dentifrice on the bond strength of brackets after erosive challenge. Eighty-four enamel specimens were divided into seven groups (n=12: WN (distilled water/no acid challenge, W3C (distilled water/3 cycles of acid challenge, and W6C (distilled water/6 cycles of acid challenge were not submitted to dentifrice treatment. Groups RF3C (regular fluoride dentifrice/3 cycles of acid challenge and RF6C (regular fluoride dentifrice/6 cycles of acid challenge were treated with dentifrices containing 1450 μg F−/g and HF3C (high fluoride dentifrice/3 cycles of acid challenge and HF6C (high fluoride dentifrice/6 cycles of acid challenge were with 5000 μg F−/g. Acid challenges were performed for seven days. After bond strength test, there was no significant difference among groups submitted to 3 cycles of acid challenge (P>0.05. Statistically significant difference was found between the regular and high fluoride dentifrices after 6 cycles of acid challenge (<0.05. Similar areas of adhesive remaining were found among control groups and among groups W6C, RF3C, RF6C, HF3C, and HF6C. The high fluoride dentifrice was able to prevent the reduction of bond strength values of brackets submitted to acid challenge. Clinical relevance: the high fluoride toothpaste prevents debonded brackets on erosive enamel.
Molecular Basis of Human Enamel Defects
Chatzopoulos Georgios
2014-03-01
Full Text Available During eruption of teeth in the oral cavity, the effect of gene variations and environmental factors can result in morphological and structural changes in teeth. Amelogenesis imperfecta is a failure which is detected on the enamel of the teeth and clinical picture varies by the severity and type of the disease. Classification of the types of amelogenesis imperfecta is determined by histological, genetic, clinical and radiographic criteria. Specifically, there are 4 types of amelogenesis imperfecta (according to Witkop: hypoplastic form, hypo-maturation form, hypo-calcified form, and hypo-maturation/hypoplasia form with taurodontism and 14 subcategories. The diagnosis and classification of amelogenesis imperfecta has traditionally been based on clinical presentation or phenotype and the inheritance pattern. Several genes can be mutated and cause the disease. Millions of genes, possibly more than 10,000 genes produce proteins that regulate synthesis of enamel. Some of the genes and gene products that are likely associated with amelogenesis imperfecta are: amelogenin (AMELX, AMELY genes, ameloblastin (AMBN gene, enamelin (ENAM gene, enamelysin (MMP20 gene, kalikryn 4 (KLK 4 gene, tuftelins (Tuftelin gene, FAM83H (FAM83H gene and WDR72 (WDR72 gene. Particular attention should be given by the dentist in recognition and correlation of phenotypes with genotypes, in order to diagnose quickly and accurately such a possible disease and to prevent or treat it easily and quickly. Modern dentistry should restore these lesions in order to guarantee aesthetics and functionality, usually in collaboration with a group of dentists.
On the Braids for 810 Knot = 810 Düğümünün Örgüsü Hakkında
Ahmet KÜÇÜK
2001-06-01
Full Text Available This paper is concerned with 810 knots and its braids. The braids structure is very important role in Knots Theory. In view of this structure, we obtained braids for that knot and we will give the representations of Artin and we examine Garside Word problem. And then we will examine the positivity structure for these knots.
Edson Luiz Lopes Baldin
2012-03-01
Full Text Available Aqueous extracts of several plant species have shown promising in controlling root-knot nematode, Meloidogyne incognita (Kofoid & White, one of the most limiting agents for carrot cultivation. The current study evaluated the effect of aqueous extracts from seven botanical species applied to 40, 50, 60, 70 and 80 days after sowing 'Nantes' carrots in soil infested with root-knot nematode. Three other treatments included cassava wastewater, distilled water (control, which were applied in the same periods of the extracts application, in addition to carbofuran 50G (80Kg/ha, which was applied once at 60 days after carrot sowing. Evaluations were performed at 90 days after inoculation to determine shoot and root fresh weight, as well as the diameter and the length of principal roots and the number of galls on primary and secondary roots. Plants treated with cassava wastewater, extracts of Ricinus communis L. seeds, Crotalaria juncea L. seeds, R. communis leaves + branches + fruits, Chenopodium ambrosioides L. leaves + branches + inflorescences and Azadirachta indica A. Juss. seeds showed the highest rates of total weight (root + shoot and shoot weight. The extract of R. communis leaves + branches + fruits provides the highest total root weight and principal root diameter. Cassava wastewater and extracts of R. communis seeds provided the highest principal root weight. The extract of R. communis seeds and cassava wastewater can be considered promising for the alternative control of M. incognita.
Some Sufficient Conditions for Tunnel Numbers of Connected Sum of Two Knots Not to Go Down
Guo Qiu YANG; Feng Chun LEI
2011-01-01
In this paper,we show the following result:Let Ki be a knot in a closed orientable 3-manifold Mi such that (Mi,Ki) is not homeomorphic to (S2 × S1,x0 × S1),i =1,2.Suppose that the Euler Characteristic of any meridional essential surface in each knot complement E(Ki) is less than the difference of one and twice of the tunnel number of Ki.Then the tunnel number of their connected sum will not go down.If in addition that the distance of any minimal Heegaard splitting of each knot complement is strictly more than 2,then the tunnel number of their connected sum is super additive.We further show that if the distance of a Heegaard splitting of each knot complement is strictly bigger than twice the tunnel number of the knot (twice the sum of the tunnel number of the knot and one,respectively),then the tunnel number of connected sum of two such knots is additive (super additive,respectively).
Effects of horseshoe crab harvest in delaware bay on red knots: Are harvest restrictions working?
Niles, L.J.; Bart, J.; Sitters, H.P.; Dey, A.D.; Clark, K.E.; Atkinson, P.W.; Baker, A.J.; Bennett, K.A.; Kalasz, K.S.; Clark, N.A.; Clark, J.; Gillings, S.; Gates, A.S.; Gonzalez, P.M.; Hernandez, D.E.; Minton, C.D.T.; Morrison, R.I.G.; Porter, R.R.; Ross, R.K.; Veitch, C.R.
2009-01-01
Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their eggs for knots. The proportion of knots achieving weights of more than 180 grams by 26-28 May, their main departure period, dropped from 0.6-0.8 to 0.14-0.4 over 1997-2007. During the same period, the red knot population stopping in Delaware Bay declined by more than 75%, in part because the annual survival rate of adult knots wintering in Tierra del Fuego declined. Despite restrictions, the 2007 horseshoe crab harvest was still greater than the 1990 harvest, and no recovery of knots was detectable. We propose an adaptive management strategy with recovery goals and annual monitoring that, if adopted, will both allow red knot and horseshoe crab populations to recover and permit a sustainable harvest of horseshoe crabs.
Sari, Mustafa Erhan; Erturk, Aliye Gediz; Koyuturk, Alp Erdin; Bekdemir, Yunus
2014-01-01
To examine different types of restorative materials used in children as well as primary and permanent teeth enamel when affected by erosive foods. Buttermilk, fruit yoghurt, Coca-cola, fruit juice, Filtek Z-250, Dyract Extra, Fuji II LC, and Fuji IX and tooth enamel were used. Measurements were performed on 1-day, 1-week, 1-month, 3-month, 6-month time periods by using ATR-FTIR technique and surface of the specimens were examined with SEM. Permanent tooth showed the least change among human tooth samples when compared to restorative materials. Among filler materials, the most change was observed in Fuji IX. In terms of beverages the most changes on absorption peaks obtained from spectra were seen on the samples held in Coca-Cola and orange-juice. The exposure of human enamel and restorative materials to acidic drinks may accelerate the degradation process and so reduce the life time of filler materials at equivalent integral exposure times longer than three months. Clinical Relevance Erosive foods and drinks having acidic potential destroy not only tooth enamel but also restorative materials. Copyright © 2013 Wiley Periodicals, Inc.
Microabrasion In Tooth Enamel Discoloration Defects: Three Cases With Long-term Follow-ups
Sundfeld, Renato Herman; Sundfeld-Neto, Daniel; Lucas Silveira MACHADO; FRANCO,Laura Molinar; FAGUNDES, Ticiane Cestari; BRISO, André Luiz Fraga
2014-01-01
Superficial irregularities and certain intrinsic stains on the dental enamel surfaces can be resolved by enamel microabrasion, however, treatment for such defects need to be confined to the outermost regions of the enamel surface. Dental bleaching and resin-based composite repair are also often useful for certain situations for tooth color corrections. This article presented and discussed the indications and limitations of enamel microabrasion treatment. Three case reports treated by enamel m...
Peptide Characterization of Mature Fluorotic and Control Human Enamel.
Lelis, Isabel Maria Porto; Molina, Gabriela F; Souza, Cláudia; Perez, Walter B; Laure, Helen J; Rosa, José C; Gerlach, Raquel F
2016-01-01
Exposure to high fluoride levels during amelogenesis causes enamel fluorosis. This study aimed to determine and compare the amino acid sequences in the enamel of fluorotic and control teeth. This investigation included enamel samples obtained from erupted and non-erupted third molars with either TF grade 4-6 (n=7) fluorosis or no sign of fluorosis (controls, n=7). The samples were kept frozen at -20 °C until protein extraction. Samples were etched and processed with a cocktail of proteinase inhibitors and immediately analyzed. Matrix Assisted Laser Desorption/Ionization-Time-Of-Flight/Time-of-Flight Mass Spectrometry (MALDI-TOF/TOF) followed by MASCOT search aided the peptides analysis. The more abundant peptides bore the N-terminal amelogenin sequences WYQSIRPPYP (which is specific for the X-encoded amelogenin) and MPLPPHPGHPGYINF (which does not show sexual dimorphism) were not different in control or fluorotic enamel. There was no missing proteolytic cleavage in the fluorotic samples, which suggested that the increased amount of protein described in fluorotic enamel did not stem from the decreased ability of proteinases to cleave the proteins in humans. This study showed how to successfully obtain peptide from superficial enamel. A relatively low number of teeth was sufficient to provide good data on the actual peptides found in mature enamel.
DESIGN AND APPLICATION OF TRANSPARENT AND TRANSLUCENT ENAMELS ON ALUMINUM
H. AHMADI MOGHADDAM
2012-09-01
Full Text Available Transparent and opaque glass enamels for aluminum plates were designed with a minimum or with no heavy atom oxides such as lead and bismuth oxides. The thermal properties of the enamels were studied by DTA and their stability as measured by the difference of glass transition and crystallization onset temperatures was determined. Bending and rapid deformation (impact tests indicated the interfacial adhesion. The enamel/aluminum interfacial qualities were viewed and examined by scanning electron microscopy (SEM. A large amount of NaF and P2O5 in their formulation created opaque enamels. The three methods of melt dipping, pouring, and sintering were used to apply layers of enamels on aluminum plates. The novelty of the pouring and spreading method and its advantages over other methods, were in the use of lower stability and higher melting point enamels, without thermally/mechanically damaging the aluminum. Observations suggested that the interfacial contact and adhesion properties were good, particularly with the transparent or glassy state enamels.
Thermal treatments modulate bacterial adhesion to dental enamel.
Hu, X L; Ho, B; Lim, C T; Hsu, C S
2011-12-01
Numerous studies have demonstrated the effects of laser-induced heat on demineralization of enamel; however, no studies have investigated the link between heat/laser-induced changes in physicochemical properties and bacterial adhesion. In this study, we investigated the effects of thermal treatment on surface properties of enamel such as hydrophobicity and zeta potential. Bacterial adhesion to treated surfaces was characterized by confocal laser scanning microscopy, and adhesion force was quantified by atomic force microscopy. The hydrophobicity of enamel increased after heating (p enamel became more negative than that of the control (p enamel after being heated (p adhesion force of both S. mitis and S. oralis to enamel with or without saliva coating. Reduction of adhesion force was statistically significant for S. mitis (p 0.05). Heating did not affect the adhesion of S. sanguis with or without saliva coating. In conclusion, thermal treatment and photothermal/laser treatments may modulate the physicochemical properties of enamel, preventing the adhesion of some bacterial species.
EFFECT OF SURFACE TREATMENT ON ENAMEL SURFACE ROUGHNESS
Şeyda Erşahan
2016-01-01
Full Text Available Purpose: To compare the effects of different methods of surface treatment on enamel roughness. Materials and Methods: Ninety human maxillary first premolars were randomly divided into three groups (n=30 according to type of enamel surface treatment: I, acid etching; II, Er:YAG laser; III, Nd:YAG laser. The surface roughness of enamel was measured with a noncontact optical profilometer. For each enamel sample, two readings were taken across the sample—before enamel surface treatment (T1 and after enamel surface treatment (T2. The roughness parameter analyzed was the average roughness (Ra. Statistical analysis was performed using a Paired sample t test and the post-hoc Mann- Whitney U test, with the significance level set at 0.05. Results: The highest Ra (average roughness values were observed for Group II, with a significant difference with Groups I and III (P<0.001. Ra values for the acid etching group (Group I were significantly lower than other groups (P<0.001. Conclusion: Surface treatment of enamel with Er:YAG laser and Nd:YAG laser results in significantly higher Ra than acid-etching. Both Er:YAG laser or Nd:YAG laser can be recommended as viable treatment alternatives to acid etching.
Development of fluorapatite cement for dental enamel defects repair.
Wei, Jie; Wang, Jiecheng; Shan, Wenpeng; Liu, Xiaochen; Ma, Jian; Liu, Changsheng; Fang, Jing; Wei, Shicheng
2011-06-01
In order to restore the badly carious lesion of human dental enamel, a crystalline paste of fluoride substituted apatite cement was synthesized by using the mixture of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA) and ammonium fluoride. The apatite cement paste could be directly filled into the enamel defects (cavities) to repair damaged dental enamel. The results indicated that the hardened cement was fluorapatite [Ca(10)(PO(4))(6)F(2), FA] with calcium to phosphorus atom molar ratio (Ca/P) of 1.67 and Ca/F ratio of 5. The solubility of FA cement in Tris-HCl solution (pH = 5) was slightly lower than the natural enamel, indicating the FA cement was much insensitive to the weakly acidic solutions. The FA cement was tightly combined with the enamel surface, and there was no obvious difference of the hardness between the FA cement and natural enamel. The extracts of FA cement caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. In addition, the results showed that the FA cement had good mechanical strength, hydrophilicity, and anti-bacterial adhesion properties. The study suggested that using FA cement was simple and promising approach to effectively and conveniently restore enamel defects.
Assessment of enamel damage after removal of ceramic brackets.
Kitahara-Céia, Flávia Mitiko Fernandes; Mucha, José Nelson; Marques dos Santos, Paulo Acioly
2008-10-01
Since the introduction of ceramic brackets, research has been performed to evaluate enamel damage caused during their removal. One problem in comparing treated and control groups is the absence of assurance that the surfaces were undamaged before the brackets were bonded and debonded, or that superficial treatment applied to the enamel could hinder damage detection. The aim of this in-vitro study was to evaluate enamel injuries during debonding of 3 types of ceramic brackets. Forty-five premolars, extracted for orthodontic purposes, were divided into 3 groups of 15. The enamel surfaces were photographed with a magnifying loupe (60 times) in an optical stereomicroscope (Stemi 2000-C, Zeiss, Oberkochen, Germany) with a digital camera. A different type of backet was bonded and debonded in each group: mechanical retention, mechanical retention with a polymer base, and chemical retention. After debonding, the surfaces were again photographed. The photographs were evaluated for quality of enamel surface according to a predetermined scale. The results were tested by method error and the chi-square test. The damage evaluation comparing the same surface before bonding and after debonding showed no significant statistical difference between the mechanical retention group and the polymer base retention group. There was a significant statistical difference (P ceramic bracket group. The difference between the enamel surfaces before bonding and after debonding brackets with chemical retention was statistically significant; bonding and debonding these brackets resulted in enamel damage.
Retinoic Acid Excess Impairs Amelogenesis Inducing Enamel Defects
Morkmued, Supawich; Laugel-Haushalter, Virginie; Mathieu, Eric; Schuhbaur, Brigitte; Hemmerlé, Joseph; Dollé, Pascal; Bloch-Zupan, Agnès; Niederreither, Karen
2017-01-01
Abnormalities of enamel matrix proteins deposition, mineralization, or degradation during tooth development are responsible for a spectrum of either genetic diseases termed Amelogenesis imperfecta or acquired enamel defects. To assess if environmental/nutritional factors can exacerbate enamel defects, we investigated the role of the active form of vitamin A, retinoic acid (RA). Robust expression of RA-degrading enzymes Cyp26b1 and Cyp26c1 in developing murine teeth suggested RA excess would reduce tooth hard tissue mineralization, adversely affecting enamel. We employed a protocol where RA was supplied to pregnant mice as a food supplement, at a concentration estimated to result in moderate elevations in serum RA levels. This supplementation led to severe enamel defects in adult mice born from pregnant dams, with most severe alterations observed for treatments from embryonic day (E)12.5 to E16.5. We identified the enamel matrix proteins enamelin (Enam), ameloblastin (Ambn), and odontogenic ameloblast-associated protein (Odam) as target genes affected by excess RA, exhibiting mRNA reductions of over 20-fold in lower incisors at E16.5. RA treatments also affected bone formation, reducing mineralization. Accordingly, craniofacial ossification was drastically reduced after 2 days of treatment (E14.5). Massive RNA-sequencing (RNA-seq) was performed on E14.5 and E16.5 lower incisors. Reductions in Runx2 (a key transcriptional regulator of bone and enamel differentiation) and its targets were observed at E14.5 in RA-exposed embryos. RNA-seq analysis further indicated that bone growth factors, extracellular matrix, and calcium homeostasis were perturbed. Genes mutated in human AI (ENAM, AMBN, AMELX, AMTN, KLK4) were reduced in expression at E16.5. Our observations support a model in which elevated RA signaling at fetal stages affects dental cell lineages. Thereafter enamel protein production is impaired, leading to permanent enamel alterations. PMID:28111553
Parabens do not increase fluoride uptake by dental enamel
Vanessa Silva Tramontino
2010-04-01
Full Text Available Objective: To evaluate whether methylparaben and propylparaben, which present a similar chemical structure, increase fluoride uptake by demineralized dental enamel when present in buffered solutions. Methods: The study comprised an in vitro experiment using blocks of bovine dental enamel with artificial carious lesions. Enamel blocks were exposed to the following treatment (n=12: fluoride solution (200 ppm fluoride - control; solution containing fluoride and 13 mM methylparaben; solution containing fluoride and 13 mM propylparaben in 35% propylene glycol; solution containing fluoride in 35% propylene glycol. All solutions were buffered (0.01 M cacodilate and the pH was adjusted to 6.27. The blocks were exposed to the treatment solutions in the proportion of 2 ml per mm2 of exposed enamel area and fluoride formed was estimated after removing an enamel layer by acid etching. Fluoride extracted was determined by ion specific electrode and the amount of enamel removed was estimated by phosphorus analysis. ANOVA followed by Tukey’s test were used for statistical analysis, with significance level at 5%. Results: The dental blocks of treatment groups containing both parabens and the control group presented similar fluoride concentration in enamel and no statistical difference was observed among them (p>0.05. The dental blocks of treatment group containing fluoride and propylene glycol showed the lowest value of fluoride present in enamel, which was significantly different from the control and fluoride and methylparaben groups (p<0.05. Conclusion: Methyl and propylparaben in a buffered solution do not enhance fluoride uptake by demineralized dental enamel.
Helicity, Topology and Kelvin Waves in reconnecting quantum knots
di Leoni, P Clark; Brachet, M E
2016-01-01
Helicity is a topological invariant that measures the linkage and knottedness of lines, tubes and ribbons. As such, it has found myriads of applications in astrophysics and solar physics, in fluid dynamics, in atmospheric sciences, and in biology. In quantum flows, where topology-changing reconnection events are a staple, helicity appears as a key quantity to study. However, the usual definition of helicity is not well posed in quantum vortices, and its computation based on counting links and crossings of vortex lines can be downright impossible to apply in complex and turbulent scenarios. We present a new definition of helicity which overcomes these problems. With it, we show that only certain reconnection events conserve helicity. In other cases helicity can change abruptly during reconnection. Furthermore, we show that these events can also excite Kelvin waves, which slowly deplete helicity as they interact nonlinearly, thus linking the theory of vortex knots with observations of quantum turbulence.
Material Properties of Wire for the Fabrication of Knotted Fences
Dirk J. Pons
2014-01-01
Full Text Available This paper describes the materials properties of galvanised fencing wire, as used in the fabrication of knotted wire fences. A range of physical properties are investigated: tensile strength, ductility in tension, Young’s modulus, three-point bending, and bending span. A range of commercially available wire products were tested. The results show that most, but not all, high tensile wire samples met the minimum tensile and ductility requirements. Young’s modulus results failed to provide any meaningful insights into wire quality. Flexural modulus results also failed to provide any insight into wire quality issues, with no statistically significant differences existing between acceptable and problematic wire batches. The implications are that premature fence failures are unlikely to be caused solely by reduced tensile properties. Existing test methods, including tensile strength and ductility, are somewhat incomplete, perhaps even unreliable, as measures of wire quality.
Disciplinary Knots and Learning Problems in Waves Physics
Di Renzone, Simone; Montalbano, Vera
2012-01-01
An investigation on student understanding of waves is performed during an optional laboratory realized in informal extracurricular way with few, interested and talented pupils. The background and smart intuitions of students rendered the learning path very dynamic and ambitious. The activities started by investigating the basic properties of waves by means of a Shive wave machine. In order to make quantitative observed phenomena, the students used a camcorder and series of measures were obtained from the captured images. By checking the resulting data, it arose some learning difficulties especially in activities related to the laboratory. This experience was the starting point for a further analysis on disciplinary knots and learning problems in the physics of waves in order to elaborate a teaching-learning proposal on this topic.
Rectangular superpolynomials for the figure-eight knot
Kononov, Ya
2016-01-01
We rewrite the recently proposed differential expansion formula for HOMFLY polynomials of the knot $4_1$ in arbitrary rectangular representation $R=[r^s]$ as a sum over all Young sub-diagrams $\\lambda$ of $R$ with extraordinary simple coefficients $D_{\\lambda^{tr}}(r)\\cdot D_\\lambda(s)$ in front of the $Z$-factors. Somewhat miraculously, these coefficients are made from quantum dimensions of symmetric representations of the groups $SL(r)$ and $SL(s)$ and restrict summation to diagrams with no more than $s$ rows and $r$ columns. They possess a natural $\\beta$-deformation to Macdonald dimensions and produces positive Laurent polynomials, which can be considered as plausible candidates for the role of the rectangular superpolynomials. Both polynomiality and positivity are non-evident properties of arising expressions, still they are true. This extends the previous suggestions for symmetric and antisymmetric representations (when $s=1$ or $r=1$ respectively) to arbitrary rectangular representations. As usual for ...
Numerical simulation of the knotted nylon netting panel
Li Yuwei
2016-01-01
Full Text Available A piece of netting, consists of the 8 8 meshes, fixed on a square frame, was simulated and the tensions and their distribution, the positions of knots and netting shape were calculated by means of MATLAB in computer. The dynamic mathematic model was developed based on lumped mass method, the netting was treated as spring-mass system, the Runge-Kutta fifth-order and sixth-order method was used to solve the differential equations for every step, then the displacement and tension of each mass point were obtained. For verify this model, the tests have been carried out in a flume tank. The results of the numerical simulation fully agreed with the experiments.
Racah matrices and hidden integrability in evolution of knots
Mironov, A; Morozov, An; Sleptsov, A
2016-01-01
We construct a general procedure to extract the exclusive Racah matrices S and \\bar S from the inclusive 3-strand mixing matrices by the evolution method and apply it to the first simple representations R =[1], [2], [3] and [2,2]. The matrices S and \\bar S relate respectively the maps (R\\otimes R)\\otimes \\bar R\\longrightarrow R with R\\otimes (R \\otimes \\bar R) \\longrightarrow R and (R\\otimes \\bar R) \\otimes R \\longrightarrow R with R\\otimes (\\bar R \\otimes R) \\longrightarrow R. They are building blocks for the colored HOMFLY polynomials of arbitrary arborescent (double fat) knots. Remarkably, the calculation realizes an unexpected integrability property underlying the evolution matrices.
Symmetric alteration of four knots of B-spline and NURBS surfaces
LI Ya-juan; WANG Guo-zhao
2006-01-01
Modifying the knots ofa B-spline curve, the shape of the curve will be changed. In this paper, we present the effect of the symmetric alteration of four knots of the B-spline and the NURBS surfaces, i.e., symmetrical alteration of the knots of surface,the extended paths of points of the surface will converge to a point which should be expressed with several control points. This theory can be used in the constrained shape modification of B-spline and NURBS surfaces.
Knot detection in X-ray images of wood planks using dictionary learning
Hansson, Nils Mattias; Enescu, Alexandru; Brandt, Sami Sebastian
2015-01-01
This paper considers a novel application of x-ray imaging of planks, for the purpose of detecting knots in high quality furniture wood. X-ray imaging allows the detection of knots invisible from the surface to conventional cameras. Our approach is based on texture analysis, or more specifically......, discriminative dictionary learning. Experiments show that the knot detection and segmentation can be accurately performed by our approach. This is a promising result and can be directly applied in industrial processing of furniture wood....
Multiple folding pathways of proteins with shallow knots and co-translational folding
Chwastyk, Mateusz
2015-01-01
We study the folding process in the shallowly knotted protein MJ0366 within two variants of a structure-based model. We observe that the resulting topological pathways are much richer than identified in previous studies. In addition to the single knot-loop events, we find novel, and dominant, two-loop mechanisms. We demonstrate that folding takes place in a range of temperatures and the conditions of most successful folding are at temperatures which are higher than those required for the fastest folding. We also demonstrate that nascent conditions are more favorable to knotting than off-ribosome folding.
Successful retrieval of a knotted pulmonary artery catheter trapped in the tricuspid valve apparatus
Muhammad Ishaq; Nicki Alexander; David H. T. Scott
2013-01-01
We report the case of a 64-year-old patient in whom a pulmonary artery catheter formed a knot fixed within the right ventricle in the region of the tricuspid valve apparatus. Knot formation is a recognized complication associated with pulmonary artery catheters (PAC) insertion. This problem is usually dealt with by simply withdrawing the PAC until the knot impacts onto the introducer and after enlarging the puncture site by a small skin incision removing the introducer-PAC as one unit. Howeve...
Nematicides and nonconventional soil amendments in the management of root-knot nematode on cotton.
Jorgenson, E C
1984-04-01
Granular and liquid commercial humates, with micronutrients, and a microbial fermentation product were compared in several combinations with nematicides for their effects on cotton lint yield and root-knot nematode suppression. Fumigant nematicides effectively reduced cotton root galling caused by root-knot nematodes, and cotton lint yields increased. Organophosphates and carbamates were not effective. Occasionally, cotton lint yields were increased or maintained with combination treatments o f humates, micronutrients, and a microbial fermentation product, but galling o f cotton roots by root-knot nematodes was usually not reduced by these treatments.
Chromatographic separation of alkaline phosphatase from dental enamel
Moe, D; Kirkeby, S; Salling, E
1989-01-01
Alkaline phosphatase (AP) was prepared from partly mineralized bovine enamel by extraction in phosphate buffer, centrifugation and various chromatographic techniques. Chromatofocusing showed that the enamel enzyme possessed five isoelectric points at the acid pH level ranging from pH 5.7 to pH 4.......4. Three enzyme peaks were eluted using low pressure chromatography with a Bio-gel column. With a HPLC gel filtration column the separation of the enamel extract resulted in only one peak with AP activity. The fractions of this peak were used to produce an antibody against bovine AP....
Microstructure and hardness of bovine enamel in roselle extract solution
Dame, M. T.; Noerdin, A.; Indrani, D. J.
2017-08-01
The aim of this study was to analyze the effect of roselle extract solution on the microstructure and hardness of bovine enamel. Ten bovine teeth and a 5% concentration of roselle extract solution were prepared. Immersions of each bovine tooth in roselle extract solution were conducted up to 60 minutes. The bovine enamel surface was characterized in hardness and microscopy. It was apparent that the initial hardness was 328 KHN, and after immersion in 15 and 60 min, the values decrease to 57.4 KHN and 11 KHN, respectively. Scanning electron microscopy (SEM) revealed changes in enamel rods after immersion in the roselle extract solution.
The precision of three enamel biopsy methods for fluoride determination.
Spörri, S; Belser, U; Mühlemann, H R
1975-10-01
3 different enamel biopsy methods were tested on 2 maxillary permanent incisors on each of 90 schoolchildren. In methods A and B the round biopsy field was bordered by copalite varnish, while method C utilized a scotch tape border. The biopsy itself resulted from etching the enamel surface with 2N perchloric acid for 7 sec for method A, and 14 sec for methods B and C. Flouride was measured with the fluoride activity electrode. The doubled etching time caused only a 30 to 40% increase of enamel removal. Method C showed the best reproducibility.
Distinguishing between enamel fluorosis and other enamel defects in permanent teeth of children
Aira Sabokseir; Ali Golkari; Aubrey Sheiham
2016-01-01
Background. The inconsistent prevalence of fluorosis for a given level of fluoride in drinking water suggests developmental defects of enamel (DDEs) other than fluorosis were being misdiagnosed as fluorosis. The imprecise definition and subjective perception of fluorosis indices could result in misdiagnosis of dental fluorosis. This study was conducted to distinguish genuine fluorosis from fluorosis-resembling defects that could have adverse health-related events as a cause using Early Childh...
De Medeiros, R C G; Soares, J D; De Sousa, F B
2012-05-01
Lesion area measurement of enamel caries using polarized light microscopy (PLM) is currently performed in a large number of studies, but measurements are based mainly on a mislead qualitative interpretation of enamel birefringence in a single immersion medium. Here, five natural enamel caries lesions are analysed by microradiography and in PLM, and the differences in their histopathological features derived from a qualitative versus a quantitative interpretation of enamel birefringence are described. Enamel birefringence in different immersion media (air, water and quinoline) is interpreted by both qualitative and quantitative approaches, the former leading to an underestimation of the depth of enamel caries mainly when the criterion of validating sound enamel as a negatively birefringent area in immersion in water is used (a current common practice in dental research). Procedures to avoid the shortcomings of a qualitative interpretation of enamel birefringence are presented and discussed. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.
Microshear Bond Strength of Adhesives to Enamel Remineralized Using Casein Phosphopeptide Agents.
Mobarak, E H; Ali, N; Daifalla, L E
2015-01-01
This study was carried out to evaluate the difference between bonding to demineralized enamel and remineralized enamel using casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACFP) or without fluoride (CPP-ACP) compared to normal enamel. Another aim was to test if the newly introduced Single Bond Universal adhesive system would show better bonding to any enamel condition in comparison to the other tested adhesive systems. The lingual enamel surfaces of 40 non carious human third molars were divided into four main groups according to the enamel condition (ground normal enamel [negative control]; demineralized enamel [positive control]; and remineralized enamel with CPP-ACP or with CPP-ACFP, respectively). Within each main group, the lingual enamel surface of each tooth was sectioned into three slabs, resulting in 30 slabs that were distributed into three subgroups according to the adhesive system utilized (Clearfil S(3) Bond Plus, Single Bond Universal, or G-aenial Bond). Two resin composite microcylinder buildups were made on each enamel slab using Filtek Z350 XT. The μSBS was evaluated at a crosshead speed of 0.5 mm/min. Modes of failure were detected using an environmental scanning electron microscope at 300× magnification. The two-way analysis of variance with repeated measures revealed a significant effect for the enamel condition. However, there was no significant effect for the type of adhesive system. The interaction between the enamel condition and the type of adhesive system was also not significant. Modes of failure were mainly adhesive except for the demineralized enamel. It showed a mixed type of failure, in which cohesive failure in enamel was recorded. All single-step self-etch adhesives revealed comparable μSBS values to ground enamel and enamel remineralized with CPP-ACP or CPP-ACFP. Bonding to demineralized enamel was ineffective. With any enamel condition, no tested single-step self-etch adhesive was superior in its bonding.
US Fish and Wildlife Service, Department of the Interior — This FY2014 progress report documents project activity for determining critical wintering sites and migration routes for juvenile red knots. Project goals, expected...
Knot numbers used as labels for identifying subject matter of a khipu
Alberto Saez-Rodriguez
2013-03-01
Full Text Available This investigation presents a new way to look at the numerical khipu, a knotted-string recording device from Pachacamac (Peru, and the types of information it contains. In addition to celestial coordinates, khipu knots apparently pertain to an early form of double-entry accounting. This study hypothesizes that the khipu sample has the recording capacity needed to register double-entry-like accounts. After the identification of its subject matter, the khipu sample was studied in an attempt to ascertain whether the knot values could represent instructions from the Inca state administration to a local accounting center. The results indicate that the numerical information in the pairing quadrants (determined by the distribution of S- and Z-knots should be read from top to bottom along the full length of the string and can then provide certain complementary details regarding the projected corn stocks of the Inca stat
PRESENCE OF RED KNOT (CALIDRIS CANUTUS IN ITE WETLANDS, TACNA, PERU
Jhonson K. Vizcarra
2012-06-01
Full Text Available The presence of Red Knot (Calidris canutus, Linnaeus 1758 in Ite Wetlands, Tacna, Peru is documented. Two individuals were observed in October 2011. This species had only one occurrence without details in this area.
The algebraic crossing number and the braid index of knots and links
Kawamuro, Keiko
2009-01-01
It has been conjectured that the algebraic crossing number of a link is uniquely determined in minimal braid representation. This conjecture is true for many classes of knots and links. The Morton-Franks-Williams inequality gives a lower bound for braid index. And sharpness of the inequality on a knot type implies the truth of the conjecture for the knot type. We prove that there are infinitely many examples of knots and links for which the inequality is not sharp but the conjecture is still true. We also show that if the conjecture is true for K and L, then it is also true for the (p,q)-cable of K and for the connect sum of K and L.
Some Dimensions of Spaces of Finite Type Invariants of Virtual Knots
Bar-Natan, Dror; Leung, Louis; Roukema, Fionntan
2009-01-01
We compute many dimensions of spaces of finite type invariants of virtual knots (of several kinds) and the dimensions of the corresponding spaces of "weight systems", finding everything to be in agreement with the conjecture that "every weight system integrates".
Biocontrol (Formulation of Bacillus firmus (BioNem)) of Root-knot ...
Key words: Bacillus firmus, Biological control, Meloidogyne incognita, Tomato. Introduction ... levels of biocontrol formulation, BioNem on root-knot nematode infestation and plant ...... Journal of invertebrate Pathology 100 (2009)94-99.
Folding of small knotted proteins: Insights from a mean field coarse-grained model
Najafi, Saeed; Potestio, Raffaello, E-mail: potestio@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)
2015-12-28
A small but relevant number of proteins whose native structure is known features nontrivial topology, i.e., they are knotted. Understanding the process of folding from a swollen unknotted state to the biologically relevant native conformation is, for these proteins, particularly difficult, due to their rate-limiting topological entanglement. To shed some light into this conundrum, we introduced a structure-based coarse-grained model of the protein, where the information about the folded conformation is encoded in bonded angular interactions only, which do not favor the formation of native contacts. A stochastic search scheme in parameter space is employed to identify a set of interactions that maximizes the probability to attain the knotted state. The optimal knotting pathways of the two smallest knotted proteins, obtained through this approach, are consistent with the results derived by means of coarse-grained as well as full atomistic simulations.
On the species status of the root-knot nematode Meloidogyne mayaguensis Rammah & Hirschmann, 1988
Karssen, G.; Liao, J.; Kan, Z.; Heese, van E.; Nijs, L.J.M.F.
2012-01-01
Holo- and paratypes of the root-knot nematodes Meloidogyne mayaguensis Rammah & Hirschmann, 1988 and M. enterolobii Yang & Eisenback, 1983 were morphometrically and morphologically compared. All observed female, male and second-stage juvenile morphometrical and morphological characters are i
Ishaq, Muhammad; Alexander, Nicki; Scott, David H T
2013-04-01
We report the case of a 64-year-old patient in whom a pulmonary artery catheter formed a knot fixed within the right ventricle in the region of the tricuspid valve apparatus. Knot formation is a recognized complication associated with pulmonary artery catheters (PAC) insertion. This problem is usually dealt with by simply withdrawing the PAC until the knot impacts onto the introducer and after enlarging the puncture site by a small skin incision removing the introducer-PAC as one unit. However, we recently encountered a situation where the PAC was knotted around the tricuspid valve apparatus and could not be withdrawn. An interventional radiologist was able to unknot the catheter and release it from the tricuspid valve. We reviewed the literature related to this topic. We believe our experience could be of use to others.
Successful retrieval of a knotted pulmonary artery catheter trapped in the tricuspid valve apparatus
Muhammad Ishaq
2013-01-01
Full Text Available We report the case of a 64-year-old patient in whom a pulmonary artery catheter formed a knot fixed within the right ventricle in the region of the tricuspid valve apparatus. Knot formation is a recognized complication associated with pulmonary artery catheters (PAC insertion. This problem is usually dealt with by simply withdrawing the PAC until the knot impacts onto the introducer and after enlarging the puncture site by a small skin incision removing the introducer-PAC as one unit. However, we recently encountered a situation where the PAC was knotted around the tricuspid valve apparatus and could not be withdrawn. An interventional radiologist was able to unknot the catheter and release it from the tricuspid valve. We reviewed the literature related to this topic. We believe our experience could be of use to others.
Microabrasion as treatment of enamel fluorosis
Ana Caroline Brito
2008-01-01
Full Text Available There is currently a trend in favor of using fluoride as a coadjuvant in reducing caries indexes, as much in underdeveloped as in developedcountries. However, simultaneously the indexes of dental fluorosis seem to grow in an inverse proportion. This is brought about by chronic ingestion of fluoride for a prolonged length of time or in high concentration. Enamel microabrasion is an effective method to remove superficial stains caused by this condition, which affects esthetics of that tissue. The use of 18% hydrochloric acid in association with pumice, despite being a simple and low cost method, has been gradually replaced due to its potential of causing damage to periodontal tissues. Thus, this article reports the treatment of a fluorosis clinical case solved with microabrasion using phosphoric acid 37%, because its costbenefit is supposedly better than with chloridric acid. The deliberate ingestion of toothpaste was the probable cause of the tooth stains. Due to the location of the teeth and to the patient’s smile, only the six upper anterior teeth were selected to receive the proposed treatment. Four clinical sessions, with a seven days interval between each other, were carried out using 37% phosphoric acid and pumice. Under rubber dam isolation, the two first sessions consisted of rubbing the acid-pumice mix on enamel surface using a rubber cup on slow speed, and abrasive paper strips on the interproximal tooth surfaces. On the two final sessions, only finishing touches were performed using a wooden spatula to manually rub the acid-pumice paste.
Er:YAG laser radiation etching of enamel
Dostalova, Tatjana; Jelinkova, Helena; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav
1996-12-01
This study compares the effects of acid treatment and Er:YAG laser radiation on the enamel. The permanent human molars were used. Oval cavities in the buccal surface were prepared and the edges of cavities were irradiated by Er:YAG radiation. The energy of laser was 105 mJ and repetition rate 1 Hz. The radiation was focused by CaF2 lens and the sample was placed in the focus. Ten samples were etched by 35 percent phosphoric acid during 60 s. Than cavities were filled with composite resin following manufacturers directions. By laser etching the structure enamel in section was rougher. The optimal connection between the enamel and composite resin was achieved in 75 percent by acid etching and in 79.2 percent by Er:YAG laser etching. Er:YAG laser etching could be alternative method for etching of enamel.
[Enamel: a unique self-assembling in mineral world].
Lignon, Guilhem; de la Dure-Molla, Muriel; Dessombz, Arnaud; Berdal, Ariane; Babajko, Sylvie
2015-05-01
Enamel is a unique tissue in vertebrates, acellular, formed on a labile scaffolding matrix and hypermineralized. The ameloblasts are epithelial cells in charge of amelogenesis. They secrete a number of matrix proteins degraded by enzymes during enamel mineralization. This ordered cellular and extracellular events imply that any genetic or environmental perturbation will produce indelible and recognizable defects. The specificity of defects will indicate the affected cellular process. Thus, depending on the specificity of alterations, the teratogenic event can be retrospectively established. Advances in the field allow to use enamel defects as diagnostic tools for molecular disorders. The multifunctionality of enamel peptides is presently identified from their chemical roles in mineralization to cell signaling, constituting a source of concrete innovations in regenerative medicine.
Influence of different phosphoric acids in enamel adhesion
Christopher Cadete de Figueiredo; Diego Alves Cunha; Igor Figueiredo Pereira; Julio Cesar Campos Ferreira Filho; Bianca Marques Santiago; Ana Maria Gondim Valença
2012-01-01
...% with and without chlorhexidine. Thirty bovine incisors were divided into two groups (n = 15), according to the type of acid etching applied in enamel – G1 (phosphoric acid 37%) and G2 (phosphoric acid 37...
Femtosecond laser etching of dental enamel for bracket bonding.
Kabas, Ayse Sena; Ersoy, Tansu; Gülsoy, Murat; Akturk, Selcuk
2013-09-01
The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.
Dental Enamel Formation and Implications for Oral Health and Disease
Rodrigo S Lacruz; Stefan Habelitz; J Timothy Wright; Michael L Paine
2017-01-01
Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing...
Protection of enamel surfaces in the oral cavity
Lazovic, Maja Bruvo
The two main diseases that can affect the tooth enamel are dental caries and dental erosion, which both are caused by exposure of the enamel surfaces to acids. In the case of dental caries, acids from bacterial metabolism cause chemical dissolution of the tooth surface, whereas acids from drinks...... and foodstuffs or gastric juice can cause dental erosion. During a lifetime the enamel surface is also exposed to fluids that can have protective effects against dental caries and erosion such as saliva, various foodstuffs, drinking water and many types of drinks. However, little is still known about simple...... inorganic interactions between different fluids and dental caries and little is also known about which saliva proteins are able to protect the enamel surface against dental erosion. Therefore, the overall aim of this thesis was to examine simple inorganic and protein related protective effects with dental...
Targeted overexpression of amelotin disrupts the microstructure of dental enamel
Lacruz, Rodrigo S; Nakayama, Yohei; Holcroft, James; Nguyen, Van; Somogyi-Ganss, Eszter; Snead, Malcolm L; White, Shane N; Paine, Michael L; Ganss, Bernhard
2012-01-01
We have previously identified amelotin (AMTN) as a novel protein expressed predominantly during the late stages of dental enamel formation, but its role during amelogenesis remains to be determined...
Bond strength of resin composite to light activated bleached enamel
2015-09-02
Sep 2, 2015 ... Total Etch etching gel (37% phosphoric acid) was ... Figure 4: Scanning electron microscope images of the enamel surface (a) no treatment (b) nonphotoactivated ... wavelengths and powers, e.g. plasma arc lamps, lasers and.
Amorphous intergranular phases control the properties of rodent tooth enamel
Gordon, Lyle M.; Cohen, Michael J.; MacRenaris, Keith W.; Pasteris, Jill D.; Seda, Takele; Joester, Derk
2015-02-01
Dental enamel, a hierarchical material composed primarily of hydroxylapatite nanowires, is susceptible to degradation by plaque biofilm-derived acids. The solubility of enamel strongly depends on the presence of Mg2+, F-, and CO32-. However, determining the distribution of these minor ions is challenging. We show—using atom probe tomography, x-ray absorption spectroscopy, and correlative techniques—that in unpigmented rodent enamel, Mg2+ is predominantly present at grain boundaries as an intergranular phase of Mg-substituted amorphous calcium phosphate (Mg-ACP). In the pigmented enamel, a mixture of ferrihydrite and amorphous iron-calcium phosphate replaces the more soluble Mg-ACP, rendering it both harder and more resistant to acid attack. These results demonstrate the presence of enduring amorphous phases with a dramatic influence on the physical and chemical properties of the mature mineralized tissue.
Factors affecting enamel and ceramic wear: a literature review.
Oh, Won-Suck; Delong, Ralph; Anusavice, Kenneth J
2002-04-01
Enamel wear by ceramics may adversely affect maintenance of the vertical dimension of occlusion and can increase the potential for thermal sensitivity. In this article, factors related to the abrasion of enamel by dental ceramics are critically reviewed. Concepts of physical, microstructural, chemical, and surface characteristics of dental ceramics on wear are presented based on research published since 1950. A PubMed search for key words (wear of enamel and ceramic) was supplemented with a hand search to identify relevant peer-reviewed articles published in English. Based on the literature, it can be concluded that material factors, their proper handling, and control of the patient's intrinsic risk factors related to wear are critically important to the reduction of enamel wear by dental ceramics.
Effect of enamel etching time on roughness and bond strength
Barkmeier, Wayne W; Erickson, Robert L; Kimmes, Nicole S; Latta, Mark A; Wilwerding, Terry M
2009-01-01
The current study examined the effect of different enamel conditioning times on surface roughness and bond strength using an etch-and-rinse system and four self-etch adhesives. Surface roughness (Ra...
Deepak Chauhan
2013-01-01
Full Text Available Objective: The purpose of this study was to determine and compare the prevalence and presentation of developmental defects of the enamel (DDE in the mixed and permanent dentition of healthy school children residing in hills. Materials and Methods: A total of 1188 healthy school children were examined using modified DDE criteria for recording enamel defects. Results: The overall prevalence of DDE of any type was (51.3% in both mixed and permanent dentition. Diffuse opacity was (25.3% the most common defect and demarcated opacity was (23.1% and whereas, enamel hypoplasia was the least prevalent defect with prevalence of (2.9%. Conclusion: The study population showed a high prevalence of DDE in primary as well as in the permanent dentition, reflecting the current increasing trend of this condition, which should be considered as a significant public health problem.
Functions of KLK4 and MMP-20 in dental enamel formation
Lu, Yuhe; Papagerakis, Petros; Yamakoshi, Yasuo; Hu, Jan C-C.; Bartlett, John D.; Simmer, James P.
2009-01-01
Two proteases are secreted into the enamel matrix of developing teeth. The early protease is enamelysin (MMP-20). The late protease is kallikrein 4 (KLK4). Mutations in MMP20 and KLK4 both cause autosomal recessive amelogenesis imperfecta, a condition featuring soft, porous enamel containing residual protein. MMP-20 is secreted along with enamel proteins by secretory stage ameloblasts. Enamel protein cleavage products accumulate in the space between the crystal ribbons, helping to support them. MMP-20 steadily cleaves accumulated enamel proteins, so their concentration decreases with depth. Kallikrein 4 is secreted by transition and maturation stage ameloblasts. KLK4 aggressively degrades the retained organic matrix following the termination of enamel protein secretion. The principle functions of MMP-20 and KLK4 in dental enamel formation are to facilitate the orderly replacement of organic matrix with mineral, generating an enamel layer that is harder, less porous, and unstained by retained enamel proteins. PMID:18627287
Knots: attractive places with high path tortuosity in mouse open field exploration.
Anna Dvorkin
2010-01-01
Full Text Available When introduced into a novel environment, mammals establish in it a preferred place marked by the highest number of visits and highest cumulative time spent in it. Examination of exploratory behavior in reference to this "home base" highlights important features of its organization. It might therefore be fruitful to search for other types of marked places in mouse exploratory behavior and examine their influence on overall behavior.Examination of path curvatures of mice exploring a large empty arena revealed the presence of circumscribed locales marked by the performance of tortuous paths full of twists and turns. We term these places knots, and the behavior performed in them-knot-scribbling. There is typically no more than one knot per session; it has distinct boundaries and it is maintained both within and across sessions. Knots are mostly situated in the place of introduction into the arena, here away from walls. Knots are not characterized by the features of a home base, except for a high speed during inbound and a low speed during outbound paths. The establishment of knots is enhanced by injecting the mouse with saline and placing it in an exposed portion of the arena, suggesting that stress and the arousal associated with it consolidate a long-term contingency between a particular locale and knot-scribbling.In an environment devoid of proximal cues mice mark a locale associated with arousal by twisting and turning in it. This creates a self-generated, often centrally located landmark. The tortuosity of the path traced during the behavior implies almost concurrent multiple views of the environment. Knot-scribbling could therefore function as a way to obtain an overview of the entire environment, allowing re-calibration of the mouse's locale map and compass directions. The rich vestibular input generated by scribbling could improve the interpretation of the visual scene.
The enamel protein amelotin is a promoter of hydroxyapatite mineralization.
Abbarin, Nastaran; San Miguel, Symone; Holcroft, James; Iwasaki, Kengo; Ganss, Bernhard
2015-05-01
Amelotin (AMTN) is a recently discovered protein that is specifically expressed during the maturation stage of dental enamel formation. It is localized at the interface between the enamel surface and the apical surface of ameloblasts. AMTN knock-out mice have hypomineralized enamel, whereas transgenic mice overexpressing AMTN have a compact but disorganized enamel hydroxyapatite (HA) microstructure, indicating a possible involvement of AMTN in regulating HA mineralization directly. In this study, we demonstrated that recombinant human (rh) AMTN dissolved in a metastable buffer system, based on light scattering measurements, promotes HA precipitation. The mineral precipitates were characterized by scanning and transmission electron microscopy and electron diffraction. Colloidal gold immunolabeling of AMTN in the mineral deposits showed that protein molecules were associated with HA crystals. The binding affinity of rh-AMTN to HA was found to be comparable to that of amelogenin, the major protein of the forming enamel matrix. Overexpression of AMTN in mouse calvaria cells also increased the formation of calcium deposits in the culture medium. Overexpression of AMTN during the secretory stage of enamel formation in vivo resulted in rapid and uncontrolled enamel mineralization. Site-specific mutagenesis of the potential serine phosphorylation motif SSEEL reduced the in vitro mineral precipitation to less than 25%, revealing that this motif is important for the HA mineralizing function of the protein. A synthetic short peptide containing the SSEEL motif was only able to facilitate mineralization in its phosphorylated form ((P)S(P) SEEL), indicating that this motif is necessary but not sufficient for the mineralizing properties of AMTN. These findings demonstrate that AMTN has a direct influence on biomineralization by promoting HA mineralization and suggest a critical role for AMTN in the formation of the compact aprismatic enamel surface layer during the maturation
CALCIFIED ECTODERMAL COLLAGENS OF SHARK TOOTH ENAMEL AND TELEOST SCALE.
MOSS, M L; JONES, S J; PIEZ, K A
1964-08-28
Amino acid analysis of protein from the enamel of shark teeth and from teleost scales shows the presence of collagens which can be classified chemically as ectodermal. This finding, together with results from a histological examination of the development of these tissues, constitutes strong evidence that both proteins are derived from the ectoderm, like the enamel of higher vertebrates. Since both are calcified, calcification cannot be a specific property of collagens of mesodermal origin alone.
DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE.
Lacruz, Rodrigo S; Habelitz, Stefan; Wright, J Timothy; Paine, Michael L
2017-07-01
Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function. Copyright © 2017 the American Physiological Society.
[Considerations in orthodontic bracket adhesion to hypoplastic and hypomineralized enamel].
Sapir, S
2007-01-01
Developmental defects of enamel are frequently observed in the pediatric and orthodontic dental clinic. Proper diagnosis may improve the clinician's dental care. The importance of prevention is emphasized as well as the proper management of adhesion of orthodontic brackets to hypoplastic and hypominerilized enamel. A review of recent research findings in this field is discussed as well as recommendations for clinical management of some common dental defects: hypoplasia, diffuse and demarcated opacities, and amelogenesis imperfecta.
Fatigue limits of enamel bonds with moist and dry techniques.
Barkmeier, Wayne W; Erickson, Robert L; Latta, Mark A
2009-12-01
Shear fatigue limit (SFL) testing, coupled with shear bond strength (SBS) measurements can provide valuable information regarding the ability of adhesive systems to bond to mineralized tooth structures. The clinical technique for enamel bonding with adhesive resins has shifted from bonding to a thoroughly dried acid conditioned surface to a moist surface to facilitate dentin bonding. The purpose of this study was to compare the performance of ethanol-containing etch-and-rinse adhesive (ERA) systems on moist and dry enamel by determining the resin composite to enamel SBS and SFL, and examining the relationship of SBS and SFL. Twelve specimens each were used to determine 24-h resin composite (Z100 - 3M ESPE) to enamel SBS to moist and dry surfaces with two ERA systems, Adper Single Bond Plus (SBP) and OptiBond Solo Plus (OBP). A staircase method of fatigue testing was used in a four-station fatigue cycler to determine the SFL of resin composite to enamel bonds (moist and dry) with the two ERA systems (20 specimens for each test condition) at 0.25Hz for 40,000 cycles. ANOVA and Tukey's post hoc test were used for the SBS data and a modified t-test with Bonferroni correction was used for comparisons of SFL. The two ERA systems each generated statistically similar SBS (p>0.05) to moist and dry enamel and the SBS of SBP was significantly higher than OBP on dry enamel (padhesive systems. The chemical composition, solvents and filler components of ERA systems may influence their ability to develop long-term durable bonds to both moist and dry enamel surfaces.
THE EFFECT OF IRRADIATION ON ENAMEL MICRO-STRUCTURE CHANGES
Harun Gunawan; Sri Angky Soekanto; Safrida Hoesin
2015-01-01
Radiotherapy plays an important role in the management of head and neck carcinoma therapy. The radiation dose ranges from 40 – 70 Gy, depends on the severity and location of the malignancy. Many patients experience an increased dental caries or sensitivity occurrence following radiotherapy. The objective of this study is to analyze the enamel micro-structure changes after irradiation. Nine polished enamel slabs were prepared from impacted 3rd molars. The slabs were flushed in non-ionic distil...
Combination effect of fluoride dentifrices and varnish on deciduous enamel demineralization
Alessandra Gatti
2011-10-01
Full Text Available The aim of this study was to evaluate the anticaries potential of 500 or 1100 ppm F dentifrices combined with fluoride varnish using a pH-cycling regimen. Seventy primary canines were covered with nail polish, leaving a 4×4 mm window on their buccal surface, and randomly assigned into 7 groups (n = 10: S: sound enamel not submitted to the pH-cycling regimen or treatment; N: negative control, submitted to the pH-cycling regimen without any treatment; D1 and D2: subjected to the pH-cycling regimen and treated twice daily with 1100 or 500 ppm F dentifrice, respectively; VF: fluoride varnish (subjected to F-varnish before and in the middle of the pH-cycling regimen; and VF+D1 and VF+D2. After 10 days, the teeth were sectioned, and enamel demineralization was assessed by cross-sectional hardness at different distances from the dental surface. Data were analyzed using a two-way ANOVA followed by Tukey's test. Dentifrice with 1100 ppm F and the combination of F-varnish with the dentifrices significantly reduced enamel demineralization compared with the negative control (p 0.05. The effect of combining F-varnish with the dentifrices was not greater than the effect of the dentifrices alone (p < 0.05. The data suggest that the combination of F-varnish with dentifrices containing 500 and 1100 ppm F is not more effective in reducing demineralization in primary teeth than the isolated effect of dentifrice containing 1100 ppm F.
Enhanced transport of materials into enamel nanopores via electrokinetic flow.
Gan, H Y; Sousa, F B; Carlo, H L; Maciel, P P; Macena, M S; Han, J
2015-04-01
The ability to infiltrate various molecules and resins into dental enamel is highly desirable in dentistry, yet transporting materials into dental enamel is limited by the nanometric scale of their pores. Materials that cannot be infiltrated into enamel by diffusion/capillarity are often considered molecules with sizes above a critical threshold, which are often considered to be larger than the pores of enamel. We challenge this notion by reporting the use of electrokinetic flow to transport solutions with molecules with sizes above a critical threshold-namely, an aqueous solution with a high refractive index (Thoulet's solution) and a curable fluid resin infiltrant (without acid etching)-deep into the normal enamel layer. Volume infiltration by Thoulet's solution is increased by 5- to 6-fold, and resin infiltration depths as large as 600 to 2,000 µm were achieved, in contrast to ~10 µm resulting from diffusion/capillarity. Incubation with demineralization solution for 192 h resulted in significant demineralization at noninfiltrated histologic points but not at resin infiltrated. These results open new avenues for the transport of materials in dental enamel. © International & American Associations for Dental Research 2015.
Theobromine Effects on Enamel Surface Microhardness: In Vitro
Grace Syafira
2013-07-01
Full Text Available Dental caries is still a dental health problem in Indonesia. Fluoride, one of the dental caries prevention material, but its safety and the danger of fluorosis is still debated. Theobromine is an alkaloid compound contained in cocoa beans. Theobromine is believed to increase enamel microhardness with mineral changes in the enamel superficial layer. Objectives: To determine the influence of theobromine on the enamel surface microhardness. Methods: This study used 40 premolar tooth crown pieces that were embedded in epoxy resin. Furthermore specimens were randomly divided into 4 groups, which were control (distilled water, theobromine 100 mg/L (T100, theobromine 500 mg/L (T500 and theobromine 1000 mg/L (T1000. Specimens were immersed for 15 minutes and microhardness test was performed using Knoop microhardness tester. Results: Increasing enamel microhardness was observed after treatment with four different theobromine concentrations. The highest icreased of enamel microhardness was shown in T1000 group and difference compared to other groups were statistically significant (p<0.05. Conclusion: theobromine is a potential dental caries prevention material due to its effect in improving the microhardness of tooth enamel.
Enamel and dentin bond strength following gaseous ozone application.
Cadenaro, Milena; Delise, Chiara; Antoniollo, Francesca; Navarra, Ottavia Chiara; Di Lenarda, Roberto; Breschi, Lorenzo
2009-08-01
To evaluate the effects of gaseous ozone application on enamel and dentin bond strength produced by two self-etching adhesive systems. The shear bond strength test was conducted to assess adhesion on enamel (protocol 1), while the microtensile bond strength test was performed on dentin (protocol 2). Protocol 1: 96 bovine incisors were randomly divided into 4 groups, and enamel surfaces were bonded in accordance with the following treatments: (1E) ozone + Clearfil Protect Bond; (2E) Clearfil Protect Bond (control); (3E) ozone + Xeno III; (4E) Xeno III (control). Ozone gas was applied for 80 s. Shear bond strength was measured with a universal testing machine. Protocol 2: 40 noncarious human molars were selected. Middle/deep dentin was exposed and bonded in accordance with the following treatments: (1D) ozone+Clearfil Protect Bond; (2D) Clearfil Protect Bond (control); (3D) ozone+Xeno III (4D) Xeno III (control). Four-mm-thick buildups were built on the adhesives, then specimens were sectioned in accordance with the nontrimming technique. Specimens were stressed until failure occurred, and failure modes were analyzed. Shear bond and microtensile bond strength data were analyzed using two-way ANOVA and Tukey's post-hoc test. No statistical differences were found between ozone treated specimens and controls, neither on enamel nor on dentin irrespective of the tested adhesive. Clearfil Protect Bond showed higher bond strength to enamel than Xeno III, irrespective of the ozone treatment (p enamel and dentin bond strength.
Effects of sports drinks and other beverages on dental enamel.
von Fraunhofer, J Anthony; Rogers, Matthew M
2005-01-01
A high percentage of people consume soft drinks that contain sugar or artificial sweeteners, flavorings, and various additives. The popularity of sports (energy) drinks is growing and this pilot study compares enamel dissolution in these and a variety of other beverages. Enamel blocks (approximately 7.0 x 5.0 x 2.5 mm) were sectioned from sound extracted human premolars and molars and measured, weighed, and immersed in the selected beverages for a total of 14 days. The pH of all beverages was measured. The enamel sections were weighed at regular intervals throughout the immersion period with the solutions being changed daily; all studies were performed in duplicate. The data were subjected to one-way ANOVA with post hoc Scheffe testing. Enamel dissolution occurred in all of the tested beverages, with far greater attack occurring in flavored and energy (sports) drinks than previously noted for water and cola drinks. No correlation was found between enamel dissolution and beverage pH. Non-cola drinks, commercial lemonades, and energy/sports drinks showed the most aggressive dissolution effect on dental enamel. Reduced residence times of beverages in the mouth by salivary clearance or rinsing would appear to be beneficial.
Partial rescue of the amelogenin null dental enamel phenotype.
Li, Yong; Suggs, Cynthia; Wright, J Timothy; Yuan, Zhi-an; Aragon, Melissa; Fong, Hanson; Simmons, Darrin; Daly, Bill; Golub, Ellis E; Harrison, Gerald; Kulkarni, Ashok B; Gibson, Carolyn W
2008-05-30
The amelogenins are the most abundant secreted proteins in developing dental enamel. Enamel from amelogenin (Amelx) null mice is hypoplastic and disorganized, similar to that observed in X-linked forms of the human enamel defect amelogenesis imperfecta resulting from amelogenin gene mutations. Both transgenic strains that express the most abundant amelogenin (TgM180) have relatively normal enamel, but strains of mice that express a mutated amelogenin (TgP70T), which leads to amelogenesis imperfecta in humans, have heterogeneous enamel structures. When Amelx null (KO) mice were mated with transgenic mice that produce M180 (TgM180), the resultant TgM180KO offspring showed evidence of rescue in enamel thickness, mineral density, and volume in molar teeth. Rescue was not observed in the molars from the TgP70TKO mice. It was concluded that a single amelogenin protein was able to significantly rescue the KO phenotype and that one amino acid change abrogated this function during development.
Gene expression and dental enamel structure in developing mouse incisor.
Sehic, Amer; Risnes, Steinar; Khan, Qalb-E-Saleem; Khuu, Cuong; Osmundsen, Harald
2010-04-01
At the mouse incisor tip the initially differentiated ameloblasts produce a thin, prism-free enamel, while further apically, in the immediate adjacent segment, the enamel thickness increases and the four-layered enamel of mouse incisor is formed. Comparative gene-expression profiling was carried out on RNA isolated from these two segments of incisor tooth germs at embryonic day (E)17.5 and at postnatal days (P)0, 1, 2, and 10 using microarrays to measure messenger RNA (mRNA) and microRNA (miRNA) species present in the segments. Validation of expression data was achieved using real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. Bioinformatic data suggested enhanced cellular apoptosis in the incisal tip segment, which, together with diminished expression of the Amelx and Enam genes, may contribute to the production of the thin enamel seen in this tooth segment. For genes exhibiting higher levels of expression in the adjacent segment where complex enamel is being formed, bioinformatic analysis suggested significant associations with cellular functions involving the actin cytoskeleton, cellular development, morphology, and movement. This is suggested to reflect that ameloblasts with Tomes' process are being organized in transverse rows, facilitating the transverse movement that results in prism decussation in the inner enamel of the adjacent segment. Bioinformatic analysis of miRNA expression data lends support to these suggestions.
An eddy-current-based sensor for preventing knots in metallic wire drawing processes
Esteban, Bernat; Riba, Jordi-Roger; Baquero, Grau; Ferrater, Cèsar
2011-06-01
During metallic wire drawing processes, the presence of knots and the failure to detect them can lead to long production interruptions, significant economic losses and a lower quality of final product. Consequently, there is a pressing need to develop methods for real-time detection and prevention of this fault. In this paper, a sensor to prevent the formation of knots during the metallic wire drawing process is presented and evaluated by means of experimental data. This fast, inexpensive, non-contact sensor is based on electromagnetic principles such as eddy current induction, magnetic reluctance variations and magnetic coupling. The proposed sensor without direct contact can detect knots in a target metallic wire by measuring the impedance variations of a calibrated sensing coil caused by either a knot or an unwound loop rising from a wire rod. The incorporation of this type of sensor into a wire-drawing machine can avoid the tightening of the knot, thereby reducing downtime and increasing the security and reliability of the process. Experiments were conducted using a scale model of the above proposed system. This allowed highlighting the sensor's potential by carrying out an automatic, real-time knot detection during steel wire drawing.
The volume conjecture, perturbative knot invariants, and recursion relations for topological strings
Dijkgraaf, Robbert; Fuji, Hiroyuki; Manabe, Masahide
2011-08-01
We study the relation between perturbative knot invariants and the free energies defined by topological string theory on the character variety of the knot. Such a correspondence between SL(2;C) Chern-Simons gauge theory and the topological open string theory was proposed earlier on the basis of the volume conjecture and AJ conjecture. In this paper we discuss this correspondence beyond the subleading order in the perturbative expansion on both sides. In the computation of the perturbative invariants for the hyperbolic 3-manifold, we adopt the state integral model for the hyperbolic knots, and the factorized AJ conjecture for the torus knots. On the other hand, we iteratively compute the free energies on the character variety using the Eynard-Orantin topological recursion relation. We discuss the correspondence for the figure eight knot complement and the once punctured torus bundle over S with the monodromy LR up to the fifth order. For the torus knots, we find trivial the recursion relations on both sides.
The volume conjecture, perturbative knot invariants, and recursion relations for topological strings
Dijkgraaf, Robbert, E-mail: r.h.dijkgraaf@uva.n [Institute for Theoretical Physics and KdV Institute for Mathematics, University of Amsterdam, Spui 21, 1012 WX Amsterdam (Netherlands); Fuji, Hiroyuki, E-mail: fuji@th.phys.nagoya-u.ac.j [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Manabe, Masahide, E-mail: d07002p@math.nagoya-u.ac.j [Graduate School of Mathematics, Nagoya University, Nagoya 464-8602 (Japan)
2011-08-01
We study the relation between perturbative knot invariants and the free energies defined by topological string theory on the character variety of the knot. Such a correspondence between SL(2;C) Chern-Simons gauge theory and the topological open string theory was proposed earlier on the basis of the volume conjecture and AJ conjecture. In this paper we discuss this correspondence beyond the subleading order in the perturbative expansion on both sides. In the computation of the perturbative invariants for the hyperbolic 3-manifold, we adopt the state integral model for the hyperbolic knots, and the factorized AJ conjecture for the torus knots. On the other hand, we iteratively compute the free energies on the character variety using the Eynard-Orantin topological recursion relation. We discuss the correspondence for the figure eight knot complement and the once punctured torus bundle over S{sup 1} with the monodromy L{sup 2}R up to the fifth order. For the torus knots, we find trivial the recursion relations on both sides.
The Volume Conjecture, Perturbative Knot Invariants, and Recursion Relations for Topological Strings
Dijkgraaf, Robbert; Manabe, Masahide
2010-01-01
We study the relation between perturbative knot invariants and the free energies defined by topological string theory on the character variety of the knot. Such a correspondence between SL(2;C) Chern-Simons gauge theory and the topological open string theory was proposed earlier on the basis of the volume conjecture and AJ conjecture. In this paper we discuss this correspondence beyond the subleading order in the perturbative expansion on both sides. In the computation of the perturbative invariants for the hyperbolic 3-manifold, we adopt the state integral model for the hyperbolic knots, and the factorized AJ conjecture for the torus knots. On the other hand, we iteratively compute the free energies on the character variety using the Eynard-Orantin topological recursion relation. We check the correspondence for the figure eight knot complement and the once punctured torus bundle over S^1 with the holonomy L^2R up to the fourth order. For the torus knots, we find trivial the recursion relations on both sides.
Condensates and instanton - torus knot duality. Hidden Physics at UV scale
Gorsky, A
2014-01-01
We establish the duality between the torus knot superpolynomials or the Poincare polynomials of the Khovanov homology and particular condensates in Omega-deformed 5D supersymmetric QED compactified on a circle with 5d Chern-Simons(CS) term. This is the generalization of the Witten's recipe of the evaluation of the knot polynomials via Wilson loops in 3d CS theory for case of the torus knots. It is explicitly shown that $n$-instanton contribution to the condensate of the massless flavor in the background of four-observable, which can be associated with some composite defect, exactly coincides with the superpolynomial of the T(n,nk+1) torus knot where k - is the level of CS term. In contrast to the previously known results, the particular torus knot corresponds not to the partition function of the gauge theory but to the particular instanton contribution and summation over the knots has to be performed in order to obtain the complete answer. The instantons are sitting almost at the top of each other and the phy...
The X-ray emission from the knots in 3C 120
无
2010-01-01
3C 120 is a Seyfert galaxy with a well detected X-ray jet.We investigate the X-ray emission of its five jet knots and fit their spectral energy distributions(SEDs) from the radio to the X-ray bands with a single-zone lepton model.We find that the SEDs of knots k7,s2,and s3 can be explained by synchrotron radiation,and the X-rays are the simple extension of the radio-optical emission component,but that of the inner knot k4 requires the IC/CMB model,in which the X-rays are due to the inverse Compton scattering of the cosmic microwave background photons by relativistic electrons in the jet with a beaming factor δ-14.The outer knot k25 is resolved into a three-part sub-structure.It is shown that the fitting of the X-rays from this knot with the IC/CMB model needs an extraordinary beaming factor δ-15-25 for a jet at the kpc scale.If the X-rays of knot k25 are produced by synchrotron radiation similar to k7,s2,and s3,they may be contributed by a relativistic electron population whose radiations in other wavelengths are not detected.
Knotted Vortices: Entropic Lattice Boltzmann Method for Simulation of Vortex dynamics
Boesch, Fabian; Chikatamarla, Shyam; Karlin, Ilya
2013-11-01
Knotted and interlinked vortex structures in real fluids are conjectured to play a major role in hydrodynamic flow dissipation. Much interest lies in determining their temporal stability and the mechanism through which knots dissolve. Kleckner and Irvine recently have shown the existence of such knotted vortices experimentally by accelerating hydrofoils in water. In the present work we employ the entropic lattice Boltzmann method (ELBM) to perform DNS simulations of the creation and dynamics of knotted vortex rings inspired by the experimental setup in. ELBM renders LBM scheme unconditionally stable by restoring the second law of thermodynamics (the Boltzmann H-theorem), and thus enables simulations of large domains and high Reynolds numbers with DNS quality. The results presented in this talk provide an in-depth study of the dynamics of knotted vortices and vortex reconnection events and confirm the existence of trefoil knots in silicio for the first time. This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS) under project ID s347.
Freely Expanding X-ray Ejecta Knots in Kepler's Supernova Remnant
Hughes, John Patrick; Sato, Toshiki
2017-08-01
Using archival data from the Chandra X-ray Observatory, we measure the proper motions and radial velocities of compact X-ray bright knots in Kepler's supernova remnant (SNR). The high speed ejecta knots are morphologically and kinematically distinct from the rest of the ejecta and appear only in specific, limited locations. The highest speed knots show both large proper motions and high radial velocities with estimated space velocities of 10,000 km/s, similar to the typical Si velocity seen in Type Ia supernovae near maximum light. The proper motions of five knots extrapolate back over the age of the remnant to a consistent central position, defining a kinematic center for Kepler's SNR. Our new explosion center agrees well with previous determinations, but suffers less from systematic uncertainty. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 speeds and expansion indices consistent with decelerated ejecta knots. The differences in the expansion rates are likely a function of differences in the ambient medium density surrounding Kepler’s SNR.
A DECADE-BASELINE STUDY OF THE PLASMA STATES OF EJECTA KNOTS IN CASSIOPEIA A
Rutherford, John; Dewey, Daniel; Figueroa-Feliciano, Enectali; Heine, Sarah N. T.; Canizares, C. R.; Bastien, Fabienne A.; Sato, Kosuke, E-mail: enectali@mit.edu, E-mail: jmrv@mit.edu [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2013-05-20
We present the analysis of 21 bright X-ray knots in the Cassiopeia A supernova remnant from observations spanning 10 yr. We performed a comprehensive set of measurements to reveal the kinematic and thermal state of the plasma in each knot, using a combined analysis of two high energy resolution High Energy Transmission Grating (HETG) and four medium energy resolution Advanced CCD Imaging Spectrometer (ACIS) sets of spectra. The ACIS electron temperature estimates agree with the HETG-derived values for approximately half of the knots studied, yielding one of the first comparisons between high resolution temperature estimates and ACIS-derived temperatures. We did not observe the expected spectral evolution-predicted from the ionization age and density estimates for each knot-in all but three of the knots studied. The incompatibility of these measurements with our assumptions has led us to propose a dissociated ejecta model, with the metals unmixed inside the knots, which could place strong constraints on supernova mixing models.
Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia
Devi Eka Juniarti
2010-09-01
Full Text Available Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel hypoplasia is a developmental defect caused by the lack of matrix amount which leads to thin and porous enamel. Enamel hypoplasia can also be caused by matrix calcification disturbance starting from the formation and development of enamel matrix causing defect and permanent changes which can occur on one or more tooth. Purpose: The aim of the study is to improve dental discoloration and tooth surface texture on anterior maxillary teeth with enamel hypoplasia by using indirect veneer with porcelain material. Case: A 20 years-old woman with enamel hypoplasia came to the Dental Hospital, Faculty of Dentistry Airlangga University. The patient wanted to improve her anterior maxillary teeth. It is clinically known that there were some opaque white spots (chalky spotted and porous on anterior teeth’s surface. Case management: Indirect veneer with porcelain material had been chosen as a restoration treatment which has excellent aesthetics and strength, and did not cause gingival irritation. As a result, the treatment could improve the confidence of the patient, and could also make their function normal. Conclusion: Indirect veneer is an effective treatment, which can improve patient’s appearance and self confidence.Latar belakang: Saat ini perbaikan estetik menjadi suatu kebutuhan. Kebutuhan akan estetik dipengaruhi latar belakang penderita, terutama karir, status sosial dan ekonomi. Hal ini disebabkan, kelainan estetik seperti diskolorasi, malposisi
Tooth Enamel, the Result of the Relationship between Matrix Proteins and Hydroxyapatite Crystals
Carmen Mihaela MIHU
2008-12-01
Full Text Available Enamel, a structure of epithelial origin, represents a protective tooth cover. The cells responsible for the formation of enamel, ameloblasts, are lost at the time of tooth eruption, so that enamel becomes an acellular structure that can no longer regenerate. In order to compensate for this particular phenomenon, enamel has acquired a complex structural organization and a high mineralization degree, in its mature state. This reflects the particular life cycle of ameloblasts and the unique physico-chemical characteristics of matrix proteins, which regulate the formation of the extremely long crystals of enamel. These characteristics differentiate enamel from all the other tissues of the organism.
Multiple abnormalities in permanent maxillary incisors following trauma to the primary dentition
Nitesh Tewari
2011-01-01
Full Text Available Diverse consequences to the trauma to primary dentition are sometimes difficult to explain. This report describes a rare case of sequelae to primary tooth trauma. The traumatic episode which occurred at the age of 3 years resulted in abnormally large crowns of 11 and 21 with yellowish-brown discoloration and enamel hyperplasia. It also led to dilaceration in the root of 21 and enamel hypoplasia with discoloration in 12 and 22.
Kensche, A; Dähne, F; Wagenschwanz, C; Richter, G; Viergutz, G; Hannig, C
2016-05-01
The present study aimed to evaluate the suitability of self-etch adhesives for restoration of deciduous teeth compared with etch and rinse approaches. One hundred twenty primary teeth were divided into five groups, each being assigned to an adhesive system. Self-etch adhesives XenoV (XV) and Clearfil S(3) Bond (CB), Prime&Bond NT with (PBE)/without preliminary etching (PBN), and Optibond FL (OBFL) as an etch and rinse system were included. Enamel and dentin specimens were prepared (n = 36/group), adhesives applied, and compomer cylinders polymerized. After 24-h storage in 37 °C distilled water and thermo-cycling (1440 cycles, 5/55 °C, 27 s), shear bond tests and fracture mode classification based on SEM investigation were performed. Statistical analysis involved ANOVA and Scheffé procedure with Bonferroni-Holm correction (p ≤ 0.005). High shear bond strengths to primary enamel were determined for PBE (mean [M] = 22.48 ± 7.7 MPa) > OBFL (M = 19.06 ± 5.62 MPa) > CB (M = 17.6 ± 6.55 MPa), and XV (M = 16.85 ± 5.38 MPa) and PBN (M = 8.26 ± 4.46 MPa) formed significantly less reliable enamel-resin interfaces (p ≤ 0.005). PBE generated the highest bond strength on primary dentin (M = 21.97 ± 8.02 MPa); significantly lower values were measured for XV (M = 13.44 ± 5.43 MPa) and OBFL (M = 12.92 ± 4.31 MPa) (p ≤ 0.005). Adhesives requiring preliminary etching ensure optimal bond strength to primary enamel. If separate etching is to be avoided, selected self-etch adhesives obtain acceptable shear bond values on primary enamel and dentin. The treatment of pediatric patients presents a great challenge in dental practice, and optimization of treatment processes is important.
Ramnarayan, K.; Bohr, Henrik; Jalkanen, Karl J.
2008-01-01
We present different means of classifying protein structure. One is made rigorous by mathematical knot invariants that coincide reasonably well with ordinary graphical fold classification and another classification is by packing analysis. Furthermore when constructing our mathematical fold...... classifications, we utilize standard neural network methods for predicting protein fold classes from amino acid sequences. We also make an analysis of the redundancy of the structural classifications in relation to function and ligand binding. Finally we advocate the use of combining the measurement of the VA......, VCD, Raman, ROA, EA and ECD spectra with the primary sequence as a way to improve both the accuracy and reliability of fold class prediction schemes....
Avoine, Xytilis; Lussier, Bertrand; Brailovski, Vladimir; Inaekyan, Karine; Beauchamp, Guy
2016-04-01
The influence of the type of material used, knot configuration, and use of an additional throw on the tensile force at failure, the elongation, and the mode of failure of different configurations of linear sutures and knotted suture loops was evaluated in this in-vitro mechanical study. We hypothesized that all types of knots would significantly influence the initial force and elongation of suture materials and would influence the force and elongation at which the knotted loops break, but not their mode of failure. A total of 432 samples of 4 types of size 3-0 suture material (polydioxanone, polyglecaprone 25, polyglactin 910, and nylon), representing 9 configurations, were tested in a tensiometer. The configurations were 1 linear suture without a knot and the following loops: square (SQ) knot; surgeon's (SU) knot; granny (GR) knot; and sliding half-hitch (SHH) knot using either 4 and 5 or 3 and 4 throws, depending on the material. For polydioxanone, SQ and SU knots did not decrease the initial force at failure of the suture. Granny (GR) and SHH knots decreased the tensile force at failure and elongation by premature failure of the loop. For polyglecaprone 25, all knots decreased the initial force at failure of the suture, with SHH being weaker than the other knots. For coated polyglactin 910, all knots decreased the initial force at failure of the suture and slippage increased significantly compared with the other 3 sutures. The use of SQ knots with 3 throws did not result in a safe knot. For nylon, knots did not alter the original mechanics of the suture. In conclusion, all knots and types of suture material do not necessarily have the same effect on the initial tensile force at failure of suture materials.
Truin, G J; van't Hof, M A
2005-01-01
In a double-blind randomized controlled clinical trial, the caries-reducing effect of semi-annually applied fluoride gel in a low-caries child population initially aged 4.5-6.5 years (n = 773) has been investigated. Secondary analyses of the data were performed to study the caries reduction including non-cavitated lesions. The treatment effect of fluoride gel was calculated as preventive fraction (PF). When enamel lesions were included in DFS count (D(2) grade), the PF was 22% as compared to 26% counting dentinal lesions. The PFs showed that the mean effect of professionally applied fluoride gel was highest (71%) for D(3)S in the permanent dentition and lowest for d(3)s in the primary dentition (5%). The PFs for approximal and buccal and lingual surfaces of the permanent dentition significantly decreased from 80 to 25% and from 60 to 37% when enamel lesions (D(2)S) were included. With the exception of the buccal and lingual surfaces, in the primary dentition the PFs varied slightly when enamel lesions were included. Inclusion of non-cavitated lesions in the treatment effect statistics did not change the former conclusion that the treatment effect of fluoride gel application on dental caries reduction in a low-caries child population was considered not clinically relevant.
COMPARATIVE STUDY OF SHEAR BOND STRENGTH OF GLASS IONOMER TO HYPOPLASTIC ENAMEL AND NORMAL ENAMEL
S.H MORTAZAVI
2000-09-01
Full Text Available Introduction. Glass ionomer materials have been, used for years as liners, bases and temporary restoration for children. Their bonding properties allow temporization, which would be difficult with conventional cements of restorative materials. The desirable properties include easy and rapid application, fluoride release, biocompatibility and adhesion to dentin and enamel tend to be used in children specially for precooperative or handicapped children and preclude the need for treatment using general anesthesia of sedation in this research, shear bond strength of glass ionomer in two groups, including normal group and hypoplastic enamel group is tested. Methods. For this purpose, 2 groups each including 12 samples of normal anterior deciduous teeth and hypoplastic anterior deciduous teeth (with attention to hypoplastic indices were chosen. The labial surface of teeth were prepared with medium and fine size discs, chem fil glass ionomer cement was bonded to prepared surfaces of teeth, and then samples were fixed in special site of self curing acrylic. The specimens were tested with a model 4031 instron machine. A shear load was applied to the base of the bonded glass ionomer cylinder with a knife edge rod (width, 0.5 mm at a cross head speed of 0.5 mm/mm. Results. The mean of obtained sbs for 2 groups was 16.35 and 11.63 KGF/mm2. Conclusions. Statistical analysis of the results showed significant defferences between studied groups. But with attention to desirable properties, application of glass ionomer cement in hypoplastic defects of enamel in children is recommended.
Bjørndal, L.; Darvann, T.A.; Thylstrup, Anders
1998-01-01
Carious lesions, Computerized histomorphology, Dental pulp, Dentine, Enamel, Microradiography, Odontoblast......Carious lesions, Computerized histomorphology, Dental pulp, Dentine, Enamel, Microradiography, Odontoblast...
Dental enamel defects in German medieval and early-modern-age populations.
Lang, J; Birkenbeil, S; Bock, S; Heinrich-Weltzien, R; Kromeyer-Hauschild, K
2016-11-01
Aim of this study was to investigate the frequency and type of developmental defects of enamel (DDE) in a medieval and an early-modern-age population from Thuringia, Germany. Sixty-six skeletons subdivided into 31 single burials (12(th)/13(th) c.) and 35 individuals buried in groups (15(th)/16(th) c.) were examined. DDE were classified on 1,246 teeth according to the DDE index. Molar-incisor-hypomineralisation (MIH), a special type of DDE, was recorded according to the European Academy of Paediatric Dentistry (EAPD) criteria. DDE was found in 89.4% of the individuals (single burials 90.3% and group burials 88.6%). Hypoplastic pits were the most frequent defect in primary teeth and linear enamel hypoplasia (LEH) in permanent teeth. 13 individuals (24.1%) showed at least one hypomineralised permanent tooth, 12.2% had MIH on at least one first permanent molar and 10.0% in permanent incisors. Second primary molars were affected in 8.0% of the children and juveniles. No individual suffered from affected molars and incisors in combination. Endogenous factors like nutritional deficiencies and health problems in early childhood could have been aetiological reasons of DDE and MIH. The frequency of DDE and MIH might have been masked by extended carious lesions, dental wear and ante-mortem tooth loss.
Beyond the Map: Enamel Distribution Characterized from 3D Dental Topography
Thiery, Ghislain; Lazzari, Vincent; Ramdarshan, Anusha; Guy, Franck
2017-01-01
Enamel thickness is highly susceptible to natural selection because thick enamel may prevent tooth failure. Consequently, it has been suggested that primates consuming stress-limited food on a regular basis would have thick-enameled molars in comparison to primates consuming soft food. Furthermore, the spatial distribution of enamel over a single tooth crown is not homogeneous, and thick enamel is expected to be more unevenly distributed in durophagous primates. Still, a proper methodology to quantitatively characterize enamel 3D distribution and test this hypothesis is yet to be developed. Unworn to slightly worn upper second molars belonging to 32 species of anthropoid primates and corresponding to a wide range of diets were digitized using high resolution microcomputed tomography. In addition, their durophagous ability was scored from existing literature. 3D average and relative enamel thickness were computed based on the volumetric reconstruction of the enamel cap. Geometric estimates of their average and relative enamel-dentine distance were also computed using 3D dental topography. Both methods gave different estimations of average and relative enamel thickness. This study also introduces pachymetric profiles, a method inspired from traditional topography to graphically characterize thick enamel distribution. Pachymetric profiles and topographic maps of enamel-dentine distance are combined to assess the evenness of thick enamel distribution. Both pachymetric profiles and topographic maps indicate that thick enamel is not significantly more unevenly distributed in durophagous species, except in Cercopithecidae. In this family, durophagous species such as mangabeys are characterized by an uneven thick enamel and high pachymetric profile slopes at the average enamel thickness, whereas non-durophagous species such as colobine monkeys are not. These results indicate that the distribution of thick enamel follows different patterns across anthropoids. Primates might
Masashi TAKAHASHI; Shin-Ichi GOTO; Kazuhisa MORI; Izumi MATAGA
2008-01-01
The purpose of this study is to clarify the dif-ference of histology and elemental composition of the cer-vical enamels among the human permanent teeth. The re-ground surfaces at the cervical enamels of them were observed under scanning electron microscopy (SEM). The contents of seven elements were analyzed quantita-tively with electron probe microanalyzer (EPMA). The widths of the rod sections at the cervical enamels were larger than those at the cuspal enamels. The rod sections at the mesial cervical enamels in the incisors were more obscure and more decayed by acid solution than those in the premolars and molars. The calcium and phosphorus contents of the cervical enamels were significantly lower than those of the cuspal enamels. The carbon content of the cervical enamels was significantly higher than that of the cuspal enamels. The calcium and phosphorus contents of the cervical enamels were the significantly highest in the premolars. The carbon and sodium contents of the cer-vical enamels were significantly highest in the premolars. It is thought that the calcification level is lower, while the content of organic matter is higher at the cervical enamels than those at the cuspal enamels. It is considered that the sodium causes high calcification.