62 research outputs found
The Human Sweet Tooth
Humans love the taste of sugar and the word "sweet" is used to describe not only this basic taste quality but also something that is desirable or pleasurable, e.g., la dolce vita. Although sugar or sweetened foods are generally among the most preferred choices, not everyone likes sugar, especially at high concentrations. The focus of my group's research is to understand why some people have a sweet tooth and others do not. We have used genetic and molecular techniques in humans, rats, mice, cats and primates to understand the origins of sweet taste perception. Our studies demonstrate that there are two sweet receptor genes (TAS1R2 and TAS1R3), and alleles of one of the two genes predict the avidity with which some mammals drink sweet solutions. We also find a relationship between sweet and bitter perception. Children who are genetically more sensitive to bitter compounds report that very sweet solutions are more pleasant and they prefer sweet carbonated beverages more than milk, relative to less bitter-sensitive peers. Overall, people differ in their ability to perceive the basic tastes, and particular constellations of genes and experience may drive some people, but not others, toward a caries-inducing sweet diet. Future studies will be designed to understand how a genetic preference for sweet food and drink might contribute to the development of dental caries
Evolution and development of the adelphophagic, intracapsular Schmidtâs larva of the nemertean Lineus ruber
Laser-Plasma Sources for Soft-X-Ray Projection Lithography
Results are reported concerning high-repetition-rate excimer lasers with average powers up to 415 W and their usage for generating laser-plasma soft X-ray sources. A conversion efficiency of laser light into monochromatized soft X-ray radiation of 0.7% at 13.5 nm (2% bandwidth) was achieved using an excimer laser of which the beam quality was adapted for this application. Two methods to mitigate the production of plasma debris have been analyzed: tape targets and the use of Kr as a buffer gas. The optimum coating thickness of tape targets coated with Ta has determined to be 1 mum. Ta tape targets and the Kr buffer were used in a debris contamination test of 10(5) pulses. After this exposure, the reflectivity of a normal incidence Mo-Si multilayer mirror that faced the plasma, was found to be 18% lower. The contamination could be removed by cleaning, which restored the reflectivity to 97% of the initial value
Soft-X-Ray Projection Lithography Using a High-Repetition-Rate Laser-Induced X-Ray Source for Sub-100 Nanometer Lithography Processes
In this paper we present the status of a joint development programme on soft x-ray projection lithography (SXPL) integrating work on high brightness laser plasma sources. fabrication of multilayer x-ray mirrors. and patterning of reflection masks. We are in the process of optimization of a laser-plasma x-ray source and measured the conversion-efficiency of laser light into x-rays. Furthermore we present results of etching patterns in x-ray reflection masks and we discuss improved deposition techniques to produce multilayer coatings with enhanced reflectivity
PreferĂȘncias por alimentos doces e cĂĄrie dentĂĄria em prĂ©-escolares Taste preference for sweetness and caries prevalence in preschoolchildren
OBJETIVO: Avaliar as preferĂȘncias pelo sabor doce e sua associação com as condiçÔes socioeconĂŽmicas e a prevalĂȘncia de cĂĄrie dentĂĄria em prĂ©-escolares. MĂTODOS: A amostra foi composta por 572 crianças de 4 a 6 anos, matriculadas em prĂ©-escolas, dividida em estratos socioeconĂŽmicos segundo a procedĂȘncia (um bairro central, um perifĂ©rico e Programa de Desfavelamento). Estudo transversal, foi desenvolvido em duas etapas. A preferĂȘncia pelo sabor doce foi avaliada atravĂ©s do Sweet Preference Inventory modificado. A concentração das soluçÔes variou de 0 a 400 g/litro (0 a 1,17 molar). Foi utilizado o Ăndice ceos para verificar a prevalĂȘncia de cĂĄrie. RESULTADOS: Foram encontradas diferenças estatisticamente significantes entre as crianças do Programa de Desfavelamento e dos demais grupos na preferĂȘncia pelo sabor doce e no consumo de açĂșcar, bem como associação entre a procedĂȘncia e o percentual de crianças livres de cĂĄrie, sendo o grupo do Desfavelamento o menos favorecido (p<0,05). CONCLUSĂO: Os achados sustentam a hipĂłtese de que o nĂvel socioeconĂŽmico influencia a preferĂȘncia por açĂșcar e esta, por sua vez, estĂĄ associada Ă prevalĂȘncia de cĂĄrie dentĂĄria na dentição decĂdua.<br>OBJECTIVE: To assess the preference for sweetness among preschool children and differences between less and more deprived groups. In addition, to assess whether sweet taste preference was associated with presence of caries. METHODS: The sample was composed by 572 preschool children aged between 4 and 6, distributed in three day nurseries of varied socioeconomic background. Cross-sectional study developed in two steps. Preference for sweetness was assessed using a modified version of the Sweet Preference Inventory. The solutions varied in sugar concentration from 0 to 1,17 molar (0 to 400 g / litre). The presence of caries was assessed using the defs index. The socioeconomic status of the sample was classified according to the origin of domicile. RESULTS: The variation in preference for sweetness in our sample was too small. Most children preferred the sweetest juice. This reduced the ability of this variable to explain variation in caries prevalence. Despite this limitation, our results showed that socioeconomic level influenced preference for sweetness, which in turn was associated with caries prevalence. CONCLUSION: The socioeconomic status influence the sweetness preference and this, in turn, is associated with the dental caries prevalence
Dinocyst Stratigraphy and Palaeoenvironmental Interpretation of the CretaceousâPalaeogene Boundary at Stevns Klint, Denmark
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