976 resultados para Contrast media, Photografy dental


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Throughout the coverage of Iraq since the Iran-Iraq War of the 1980s and especially since September 11, the Western mainstream Media have eschewed key historical and contextual data about Iraq, thereby serving to reduce and homogenize the complexity of the issues surrounding the region and the conflicts therein. In so doing, the media has tended towards Orientalism (Said, 1978) by trivialising Iraq and its people and thereby reinforcing the hegemony of the West over the ‘backward, barbaric’ East. Building on earlier research (Isakhan, 2005a), this paper further examines the reductive and homogenising reporting of Iraq in the Western media by using both quantitative and qualitative assessment methods to compare and contrast the discursive practices used to construct the Iraqi election of December 15, 2005 in Australia’s leading daily newspapers with newspapers from the Middle East. In essence, it finds that while the Australian media propagates Orientalism through its one-eyed coverage, the Middle Eastern papers are more contemplative, focusing on the impact that this election could have throughout the region.

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This paper analyses in detail the coverage of two milestones in Iraq's shift towards democracy: the drafting and approval of the constitution by Iraq s interim government (August 2005) and the ratification of this constitution via the Iraqi polls (October 2005). Aside from some rudimentary quantitative analysis, a critical discourse analysis method is utilised to compare and contrast the discursive practices used in three of Australia s leading daily newspapers (The Australian, The Sydney Morning Herald and The Age) with three Middle Eastern English-language papers (The Daily Star, Anadolu Agency and the Jordan Times). The paper finds that the Australian print media continues the neo-Orientalist tradition of media coverage of Middle Eastern democracy, while the Middle Eastern press eschews these discourses in favour of a more open, varied debate on Iraq s constitution and the future of democracy across the region.

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Purpose – When assessing the psychometric properties of measures and estimate relations among latent variables, many studies in the social sciences (including management and marketing) often fail to comprehensively appraise the directionality of indicants. Such failures can lead to model misspecification and inaccurate parameter estimates. The purpose of this paper is to apply a post hoc test called confirmatory vanishing tetrad analysis (CTA hereafter) to a single construct called mass media consumption information exposure, which antecedent studies conceptually posited to be a formative (causative) representation.
Design/methodology/approach – This paper analyses a consumer sample of 585 US respondents and applies the CTA test to a single construct by its inclusion in various matrices within a statistical analysis system-macro that takes into account nonnormal data characteristics. The matrices are derived from Mplus 5 through the estimation of a single-factor congeneric model. The CTA test calculates a test statistic similar to an asymptotic x2 distribution with degrees of freedom equal to the number of nonredundant tetrads tested.
Findings – The preliminary data analyses reveal that the data characteristics are nonnormal which is not uncommon in social research. The CTA results reveal that the reflective (emergent) item orientation cannot be fully ruled out as being the correct model representation. This is in contrast to prior theoretical conceptual work which would strongly support this construct being a formative representation.
Originality/value – Insofar as the authors are aware, there is no paper with a particular focus on how the CTA might not provide sound results with a demonstrated example. The paper makes a valuable contribution by discussing modelling philosophy and a procedure for directionality testing. The authors advocate the implementation of pre and post hoc tests as a key component of standard research practice.

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Structural phase transitions in natrolite have been investigated as a function of pressure and different hydrostatic media using micro-Raman scattering and synchrotron infrared (IR) spectroscopy. Natrolite undergoes two reversible phase transitions at 0.86 and 1.53 GPa under pure water pressure medium. These phase transitions are characterized by the changes in the vibrational frequencies of four- and eight-membered rings related to the variations in the bridging T−O−T angles and the geometry of the elliptical eight-ring channels under pressure. Concomitant to the changes in the framework vibrational modes, the number of the O−H stretching vibrational modes of natrolite changes as a result of the rearrangements of the hydrogen bonds in the channels caused by a successive increase in the hydration level under hydrostatic pressure. Similar phase transitions were also observed at relatively higher pressures (1.13 and 1.59 GPa) under alcohol−water pressure medium. Furthermore, no phase transition was found up to 2.52 GPa if a lower volume ratio of the alcohol−water to natrolite was employed. This indicates that the water content in the pressure media plays a crucial role in triggering the pressure-induced phase transitions in natrolite. In addition, the average of the mode Grüneisen parameters is calculated to be about 0.6, while the thermodynamic Grüneisen parameter is found to be 1.33. This might be attributed to the contrast in the rigidity between the TO4 tetrahedral primary building units and other flexible secondary building units in the natrolite framework upon compression and subsequent water insertion.

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The media in a number of Western countries, including Australia, could be forgiven for envying the growth of the Indian media in recent decades. In contrast to more mature media markets in Australia and elsewhere, the Indian media is surviving the onslaught of new media technologies including social media platforms available to news audiences as an alternative to traditional news media. However, despite the omnipresence and diversity of over 800 television channels, over 94,000 publications and hundreds of radio stations, the ‘commercial’ imperative of Indian news media has raised doubts about their capacity to meet the ‘ideals’ of the public sphere. This paper examines the Indian public sphere in terms of citizens’ increasing use of various social media platforms to express their anger, frustration and protest against the system of governance and corruption. It analyses the use of social media platforms by mainstream media, socio-political organisations and audiences alike during recent events such as the Mumbai terror attack in 2008; the anti-corruption movement in 2011; protests against a lack of safety for women in 2012–13; and the federal elections in 2014; to understand the implications for the public sphere in India. The paper outlines interplay between the mainstream media’s coverage of some of these significant events, and the audience conversations pertaining to these news events on various social media platforms. It explores the increased utilisation of social media platforms by youth and the middle class, who have often remained disengaged with governance in the country, as a sign of deepening democracy and widening public sphere in India, despite the ‘digital divide’ that still exists in the country.

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Organic ionic plastic crystals (OIPCs) are attractive as solid-state electrolytes for electrochemical devices such as lithium-ion batteries and solar and fuel cells. OIPCs offer high ionic conductivity, nonflammability, and versatility of molecular design. Nevertheless, intrinsic ion transport behavior of OIPCs is not fully understood, and their measured properties depend heavily on thermal history. Solid-state magnetic resonance imaging experiments reveal a striking image contrast anisotropy sensitive to the orientation of grain boundaries in polycrystalline OIPCs. Probing triethyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1222FSI) samples with different thermal history demonstrates vast variations in microcrystallite alignment. Upon slow cooling from the melt, microcrystallites exhibit a preferred orientation throughout the entire sample, leading to an order of magnitude increase in conductivity as probed using impedance spectroscopy. This investigation describes both a new conceptual window and a new characterization method for understanding polycrystalline domain structure and transport in plastic crystals and other solid-state conductors.

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Although racism remains an issue for social media sites such as YouTube, this focus often overshadows the site’s productive capacity to generate ‘agonistic publics’ from which expressions of cultural citizenship and solidarity might emerge. This paper examines these issues through two case studies: the recent proliferation of mobile phone video recordings of racist rants on public transport, and racist interactions surrounding the performance of a Maori ‘flash mob’ haka in New Zealand that was recorded and uploaded to YouTube. We contrast these incidents as they are played out primarily through social media, with the case of Australian Football League player Adam Goodes and the broadcast media reaction to a racial slur aimed against him by a crowd member during the AFL’s Indigenous Round. We discuss the prevalence of vitriolic exchange and racial bigotry, but also, and more importantly, the productive and equally aggressive defence of more inclusive and tolerant forms of cultural identification that play out across these different media forms. Drawing on theories of cultural citizenship along with the political theory of Chantal Mouffe, we point to the capacities of YouTube as ‘platform’, and to social media practices, in facilitating ground-up antiracism and generating dynamic, contested and confronting micropublics.

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Dental follicle is a component of tooth germs, which remain adjacent to the crown of unerupted or impacted teeth. Under the influence of pathologic changes, however, dental follicles that possess reduced epithelium can proliferate into stratified squamous epithelium as far as originate dental cysts. In order to clarify the role of apoptosis and cellular proliferation herein, expression of p53 and PCNA was examined in epithelial components of dental follicles associated with impacted third molars by means of immunohistochemistry. A total of 40 cases was included in this study being 22 cases with reduced epithelium and 18 cases with stratified epithelium. Expression of p53 expression was weak or not detected in dental follicles with reduced and stratified squamous epithelium. By contrast, PCNA positive cells were evidenced in basal and supra basal layers of the stratified squamous epithelium and in reduced epithelium of dental follicles, but without any significant statistically differences between them (P > 0.05). In conclusion, these data suggest that dental follicles possess proliferative activity as depicted by PCNA-positive nuclei in some epithelial cells. However, the biological behavior of dental follicles during the late stage of dental eruptive process may not be associated with deregulation of death and/or cell proliferation.

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The maintenance of the avulsed teeth in appropriate media for preserving the cellular viability has been important for repairing the periodontal ligament and preventing the root resorption after tooth reimplantation. Propolis is a substance capable of preserving cellular viability. This study aimed to analyze the propolis substance as a storage media for maintaining the avulsed teeth, besides to determine the ideal time period for keeping the tooth inside it. Thus, 60 maxillary right central incisors of rats were extracted and divided into five groups. In groups I and II, teeth were kept in propolis for 60 min and 6 h, respectively; in group III, teeth were kept in milk for 6 h; in group IV, teeth were kept dry for 60 min; and in group V, they were immediately reimplanted. All teeth had their root canals filled with calcium hydroxide paste. Following, teeth were reimplanted in their sockets. After 15 and 60 days, animals were killed and the obtained samples were processed in laboratory for microscopic and morphometric analyzing. The results showed that the occurrence of inflammatory resorption, dental ankylosis and the formation of the connective tissue parallel to the root surface were similar among groups. It could be verified a greater occurrence of replacement resorption in group IV when comparing to other groups. In groups I and IV, the presence of periodontal ligament-like connective tissue was substantially smaller than the other groups. Regarding to the cementum amount over the root, it could be observed that this was present in smaller amount in groups I and IV. Group II was similar to groups III and IV. Therefore, according to the results of this study, the use of propolis as a storage media for maintaining avulsed teeth could be highlighted, and the 6-h period was more appropriate than the 60-min period.

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Objective: This study evaluated the influence of light sources and immersion media on the color stability of a nanofilled composite resin. Material and Methods: Conventional halogen, high-power-density halogen and high-power-density light-emitting diode (LED) units were used. There were 4 immersion media: coffee, tea, Coke (R) and artificial saliva. A total of 180 specimens (10 mm x 2 mm) were prepared, immersed in artificial saliva for 24 h at 37 +/- 1 degrees C, and had their initial color measured with a spectrophotometer according to the CIELab system. Then, the specimens were immersed in the 4 media during 60 days. Data from the color change and luminosity were collected and subjected to statistical analysis by the Kruskall-Wallis test (p<0.05). For immersion time, the data were subjected to two-way ANOVA test and Fisher's test (p<0.05). Results: High-power-density LED (Delta E=1.91) promoted similar color stability of the composite resin to that of the tested halogen curing units (Jet Lite 4000 plus - Delta E=2.05; XL 3000 - Delta E=2.28). Coffee (Delta E=8.40; Delta L=-5.21) showed the highest influence on color stability of the studied composite resin. Conclusion: There was no significant difference in color stability regardless of the light sources, and coffee was the immersion medium that promoted the highest color changes on the tested composite resin.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The aim of this study was to evaluate the shrinkage of a microhybrid dental composite resin photo-activated by one LED with different power densities by means of speckle technique. The dental composite resin Filtek (TM) Z-250 (3M/ESPE) at color A(2) was used for the samples preparation. Uncured composite was packed in a metallic mold and irradiated during 20 s from 100 to 1000 mW cm(-2). For the photo-activation of the samples, it was used a LED prototype (Light Emission Diode) with wavelength centered at 470 nm and adjustable power density until 1 W cm(-2). The speckle patterns obtained from the bottom composite surfaces were monitored using a CCD camera without lens. The speckle field is recorded in a digital picture and stored by CCD camera as the carrier of information on the displacement of the tested surface. The calculated values were obtained for each pair of adjacent patterns and the changes in speckle contrast as a function of time were obtained from six repeated measurements. The speckle contrasts obtained from the bottom surface with 100 mW cm(-1) were smaller than those than the other power densities. The higher power densities provided the higher shrinkage.

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Objective: the Nd:YAG laser irradiation of dental enamel was evaluated in enamel demineralization experiments in a Streptococcus mutans culture media. Summary Background Data: Previous studies had shown that a continuous wave Nd:YAG laser at an energy of approximately 67 mJ may induce an increased acid resistance in human dental enamel when exposed to severe demineralization conditions. Methods: Enamel windows of 3 x 4 cm in the buccal surface were irradiated with a continuous wave Nd:YAG laser at a wavelength of 1,064 Ecm using energy densities of from 83.75 to 187.50 J/cm(2), Enamel windows of 3 x 4 cm on the lingual surface served as control (without the laser irradiation). The enamel windows were then exposed to a Streptococcus mutans culture media at a temperature of 37 degrees C for 15 and 21 days. The laser effects and demineralization were examined both by optical microscopy and scanning electron microscopy (SEM), Results: A comparison between the lased and the unlased windows of enamel showed fusion and recrystalization of the enamel and increased acid-resistance in all groups irradiated with the Nd:YAG laser, on the other hand, the 3 x 4 delimited enamel surfaces from the control group (not irradiated with the Nd:YAG laser) showed 100% deminerization, Conclusions: These findings are consistent with the finding that laser irradiation of dental results in significant reduction of the effective solubility of enamel mineral.