257,500 research outputs found
Collins English for the TOEFL Test - Practice Test Pack for the TOEFL Test
No full textImprove your score by working through realistic practice tests written by TOEFL experts. Feel completely confident about how the TOEFL Test works The Collins Practice Tests for the TOEFL Test Pack contains all the advice and practice you need to succeed in the TOEFL Test. It includes: - access to four online practice tests that replicate the real test experience. Find out your score and practise to target your weak spots through tutorials and practice exercises - a book containing two complete TOEFL tests (as featured online) with a key, audio scripts and model answers. Includes a mini-dictionary with COBUILD definitions of difficult words from the tests - a booklet with a detailed guide to every section of the test, with useful tips and strategies on how to get the best result an MP3 CD with audio for the tests in the book Also available for TOEFL Test preparation from Collins: Collins Skills for the TOEFL Test: Reading and Writing Collins Skills for the TOEFL Test: Listening and Speaking Collins Key Words for the TOEFL Test You can trust Collins COBUILD 'Practice Tests for the TOEFL Test' contains a mini-dictionary with definitions based on COBUILD content. The 4.5 -billion-word Collins Corpus is the world's largest database of the English language. It is updated every month and has been at the heart of Collins COBUILD for over 25 years.iv, 150 hlm,; 21 x 27 c
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Finite element modelling and load share analysis for involute worm gears with localised tooth contact
No full textA new approach has been developed by the authors to estimate the load share of worm gear drives, and to calculate the instantaneous tooth meshing stiffness and loaded transmission errors. In the approach, the finite element (FE) modelling is based on the modified tooth geometry, which ensures that the worm gear teeth are in localized contact. The geometric modelling method for involute worm gears allows the tooth elastic deformation and tooth root stresses of worm gear drives under different load conditions to be investigated. On the basis of finite element analysis, the instantaneous meshing stiffness and loaded transmission errors are obtained and the load share is predicted. In comparison with existing methods, this approach applies loaded tooth contact analysis and provides more accurate load capacity rating of worm gear drives
Development of a device to simulate tooth mobility
No full textObjectives: The testing of new materials under simulation of oral conditions is essential in medicine. For simulation of fracture strength different simulation devices are used for test set-up. The results of these in vitro tests differ because there is no standardization of tooth mobility in simulation devices. The aim of this study is to develop a simulation device that depicts the tooth mobility curve as accurately as possible and creates reproducible and scalable mobility curves. Materials and methods: With the aid of published literature and with the help of dentists, average forms of tooth classes were generated. Based on these tooth data, different abutment tooth shapes and different simulation devices were designed with a CAD system and were generated with a Rapid Prototyping system. Then, for all simulation devices the displacement curves were created with a universal testing machine and compared with the tooth mobility curve. With this new information, an improved adapted simulation device was constructed. Results: A simulations device that is able to simulate the mobility curve of natural teeth with high accuracy and where mobility is reproducible and scalable was developed
[Letter from C. C. Collins to Pauline Perry - April 16, 1945]
No full textLetter from C. C. Collins, Adjudication Officer for the Veterans Administration, replying to Mrs. Pauline Perry regarding the cessation of payments to her as the estranged wife of a veteran
"Autobiography of Mary C. Collins in her handwriting,"
No full textThe “Autobiography of Mary C. Collins in her handwriting,” presumably written in the 1910s, offers insight into Mary Collins missionary work amongst the Sioux Indians of Dakota Territory. The autobiography includes details on her missionary work, descriptions of the surrounding land, and narratives of the Native American people and their culture
Dr. Limone C. Collins
No full textPhotograph of Dr. Limone C. Collins, Vice President, Academic Affair
Beautiful lies? Foundational fictions in South Australian history
No full textCarolyn Collins and Paul Sendziu
Tooth-whitening activity of a novel home-bleaching system utilising thermal diffusion : a multifactorial simultaneous evaluation of efficacy at cervical, body and incisal tooth sites
No full textIntroduction The ability of a thermal diffusion system (TDS) to promote the tooth-whitening actions of a bleaching gel/bleaching activator combination product (containing a final hydrogen peroxide (H2O2) content of 10.0% (w/v)) towards discoloured 'smile-zone' teeth was examined.
Methods Fifty teeth in 15 participants aged 18-62 years were investigated. The CIE tooth shade parameters L*, a* and b*, together with Vitapan shade scores (VSSs), were simultaneously recorded at three separate tooth areas (cervical, body and incisal sites) with a novel spectrophotometric monitoring system before treatment, and also at 14 days after completion of a 10-day treatment period in which the product was applied 'at-home' (twice daily).
Results The tooth-whitening treatment administered gave rise to extremely significant increases in L*, and decreases in the a* and b* shade parameters for each of the tooth areas investigated (p <10−10). Post-treatment mean decreases in the VSS values were 8.26, 9.70 and 9.14 for the cervical, body and incisal areas respectively (p <10−8 in each case). Mean ΔE values determined post-treatment were also very highly significant for each tooth region examined (p <10−10 in each case).
Conclusions The tooth-whitening system tested exerted extremely powerful bleaching actions in all tooth areas investigated. The order of tooth-whitening effectiveness was body > incisal > cervical for Δb* and ΔE, and incisal > body > cervical for Δa* and ΔL*, and this may reflect the TDS's ability to promote the penetration of H2O2 to intrinsic stain sites
Comparison of Tooth Size Discrepancy of Three Main Ethnics in Malaysia with Bolton's Ratio
No full textThe objective of this study was to investigate the applicability of Bolton's ratios in orthodontic population of Malaysian main ethnics; Malay, Chinese and Indians. Ninety convenient samples consisting of 30 pre-orthodontic study casts from each ethnic that fits the inclusion criteria were selected. The greatest mesiodistal widths of each tooth from six to six for overall ratio and three to three for anterior ratio were measured using a digital callipers linked to Hamilton Arch Tooth System software to the nearest 0.01mm. Means of the ratios were calculated using Bolton analysis. One sample t-test statistic analysis was carried out to compare the means with Bolton values of anterior ratio and overall ratio and one-way ANOVA was used to analyze comparison between ethnic groups of the anterior ratio and the overall ratio with the level of statistical significance set at p < 0.05. However, there were no significant differences when comparing Bolton values with Chinese and Indian anterior and overall ratios. The Bolton standards could be applied to Malaysian Chinese, Indians and Malay's female. Subsequently, a specific standard should be used for the Malays orthodontic population.Article URL : http://www.ukm.my/jsm/pdf_files/SM-PDF-41-2-2012/17%20Aida%20Nur%20Ashikin.pd
Tooth formation in Sudanese children
No full textPhDThe aim of this study was to describe the average age of permanent mandibular tooth
formation in two groups of Sudanese children using a cross-sectional design following
STROBE guidelines. The Northern groups are of Arab origin whilst the Western groups
are predominantly Fur of African origin (Darfur). North Sudanese sample (844 males,
802 females) consisted of equally distributed, randomly selected healthy university
students and school children, whilst the West Sudanese (848 males, 401 females)
consisted of a convenience sample attending religious schools in camps for the internally
displaced. Panoramic radiographs (2-23 years), with known date of birth were taken.
Height and weight were also measured. Developing permanent mandibular teeth were
staged from radiographs (Moorrees et al., 1963). The mean age of attainments were
calculated using logistic regression and comparisons carried out on 331 tooth stages to
determine gender and ethnic differences. Results showed that mean age of attainment of
teeth was not significantly different between the genders within each ethnic group
(p>0.05) for 135 out of 155 stage comparisons. The mean age of attainment of teeth was
not significantly different between same sex groups in 113 out of 174 stage comparisons
(p>0.05). The canine was more advanced in females compared to males while the
reverse was true for some crown and root stages of third molars. Growth indicators
showed that all groups are undernourished (z-scores =< -2). Severe malnutrition had
minimal effect on tooth formation of M1 and M2 (p>0.05) in Northern females. The
prevalence of hypodontia (excluding third molars) was 0.7% in the Western group and
2.6% in the Northern group. The pattern of hypodontia differed between groups.
In conclusion, the within group variation for most tooth stages is considerable while the
differences between groups are small. The study represents the first radiographic
investigation of permanent tooth formation in Africa
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