Enhancement of hydrogen physisorption on single-walled carbon nanotubes resulting from defects created by carbon bombardment

The defect effect on hydrogen adsorption on single-walled carbon nanotubes (SWNTs) has been studied by using extensive molecular dynamics simulations and density functional theory (DFT) calculations. It indicates that the defects created on the exterior wall of the SWNTs by bombarding the tube wall with carbon atoms and C-2 dimers at a collision energy of 20 eV can enhance the hydrogen adsorption potential of the SWNTs substantially. The average adsorption energy for a H-2 molecule adsorbed on the exterior wall of a defected (10,10) SWNT is similar to 150 meV, while that for a H-2 molecule adsorbed on the exterior wall of a perfect (10,10) SWNT is similar to 104 meV. The H-2 sticking coefficient is very sensitive to temperature, and has a maximum value around 70 to 90 K. The electron density contours, the local density of states, and the electron transfers obtained from the DFT calculations clearly indicate that the H-2 molecules are all physisorbed on the SWNTs. At temperatures above 200 K, most of the H-2 molecules adsorbed on the perfect SWNT are soon desorbed, but the H-2 molecules can still remain on the defected SWNTs at 300 K. The detailed processes of H-2 molecules adsorbing on and desorbing from the (10,10) SWNTs are demonstrated.

Judicial (in)activism in Australia's secular commonwealth

his article addresses two aspects of Australia's soft secular government. The first aspect explains how, and asks why, judges have been inactive in helping to draw the contours of secular government in Australia. The principal reason is that much of the social regulation that provokes the interest of faith-based groups is the constitutional concern of the States, and no State Constitution claims to coordinate relations between church and state. Moreover, the electorate has twice refused to pass referenda, in 1944 and 1988, for extending a constitutional demand of secular governance to the States. However, this is not so for the Commonwealth. It falls under the restrictions of section 116 of the federal Constitution, which states: The Commonwealth shall not make any law for establishing any religion ('the establishment clause') or for imposing any religious observance, or for prohibiting the free exercise of any religion ('the free exercise clause'), and no religious test shall be required as a qualification for any office or public trust under the Commonwealth. As will be explained, while methods of legal interpretation suggest that section 116's establishment clause could place mild demands of non-discrimination on the federal Parliament, judicial inactivity in policing such demands on the Commonwealth, paradoxically, has arguably been secured by judicial activism in the High Court. A second aspect of secular government addressed is the High Court's disposal of 'the separation of church and state' as a constitutional principle in Australia. The contrast, of course, is to the United States, where for sixty years 'separation' has been given uneven recognition as a rule of constitutional law, and has undoubtedly driven the development of hard forms of secular governance in that country. The centrepiece of American secular government is the 1971 decision in Lemon v Kurtzman, where the US Supreme Court held that valid legislation had to pass three tests, ie: First, the statute must have a secular legislative purpose; second, its principal or primary effect must be one that neither advances nor inhibits religion .. . finally, the statute must not foster 'an excessive government entanglement with religion. The third 'entanglement' prong of Lemon is the modern, less ambitious, form of the 'wall of separation', prohibiting too close an engagement between church and state. As this paper will demonstrate, 'entanglement's' destiny shows how unlikely it is that 'separation' can survive as a meaningful constitutional principle in the USA. And, it will also be argued that 'separation' has even poorer prospects for import to Australia.

Amodal completion with background determines depth from monocular gap stereopsis

Grove, Gillam, and Ono [Grove, P. M., Gillam, B. J., & Ono, H. (2002). Content and context. of monocular regions determine perceived depth in random dot, unpaired background and phantom stereograms. Vision Research, 42, 1859-1870] reported that perceived depth in monocular gap stereograms [Gillam, B. J., Blackburn, S., & Nakayama, K. (1999). Stereopsis based on monocular gaps: Metrical encoding of depth and slant without matching contours. Vision Research, 39, 493-502] was attenuated when the color/texture in the monocular gap did not match the background. It appears that continuation of the gap with the background constitutes an important component of the stimulus conditions that allow a monocular gap in an otherwise binocular surface to be responded to as a depth step. In this report we tested this view using the conventional monocular gap stimulus of two identical grey rectangles separated by a gap in one eye but abutting to form a solid grey rectangle in the other. We compared depth seen at the gap for this stimulus with stimuli that were identical except for two additional small black squares placed at the ends of the gap. If the squares were placed stereoscopically behind the rectangle/gap configuration (appearing on the background) they interfered with the perceived depth at the gap. However when they were placed in front of the configuration this attenuation disappeared. The gap and the background were able under these conditions to complete amodally. (c) 2006 Elsevier Ltd. All rights reserved.

RELIGIÃO E ETNICIDADE: O HERÓI CABOCLO BERNARDO E A CONSTRUÇÃO DA IDENTIDADE ÉTNICA NA VILA DE REGÊNCIA AUGUSTA - ES

Na Vila de Regência Augusta, às margens do Rio Doce no município de Linhares - ES, uma intricada dinâmica sócio-religiosa reveste de atribuições religiosas um herói cujo feito remonta os finais do século XIX. Bernardo José dos Santos, morador da vila, ficaria conhecido em âmbito nacional como o herói Caboclo Bernardo ao ser homenageado por Princesa Isabel, por realizar o salvamento de 128 dos 142 tripulantes do naufrágio do Navio de Guerra Imperial Marinheiro , próximo à foz do Rio Doce. O evento e suas conseqüências tornaram-se um marco na história da vila, inclusive o assassinato do herói nos meados da segunda década do século XX. Na continuidade narrativa, ritual e simbólica do ato heróico do Caboclo Bernardo esta investigação lança suas preocupações. Atualmente acontece na vila, todos os anos, a Festa de Caboclo Bernardo, uma festividade para onde convergem religiosos de diversas etnias tupiniquim, botocudo, negros e caboclos com o intuito de prestar homenagens ao herói na capela que leva seu nome. Neste sentido, esta etnografia pretende analisar o processo de construção da identidade étnico-religiosa na vila, pois, ele acontece concomitantemente e está umbilicalmente relacionado ao processo que eleva o herói ao patamar dos santos padroeiros das bandas de congo na região. Para isso, analisado será o contexto dramático onde a identidade da vila é construída; as confluências históricas, narrativas e simbólicas que contribuem para a atual configuração da identidade; e o contexto político-institucional organizado em torno do Caboclo Bernardo, paradigma central da construção da identidade. O método etnográfico, a antropologia interpretativa e a antropologia visual forneceram os contornos metodológicos desta investigação, que se constituiu como uma descrição densa.(AU)

JORNALISMO DIVERSIONAL: função, contornos e práticas na imprensa brasileira

Há, dentre os gêneros jornalísticos, especialmente os praticados na imprensa brasileira, um agrupamento a que José Marques de Melo atribui o nome de jornalismo diversional. Diferenciado por sua finalidade afeita à diversão e por abranger matérias reveladoras de histórias interessantes, a estrutura de seus formatos assimila elementos da literatura e da antropologia. Mas que motivações levam repórteres a desenvolver tal gênero e em quais circunstâncias? Quais métodos são adotados para sua feitura? Que forças agem aí? O estudo apresentado nesta tese buscou compreender como se dá esse processo, observando e comparando os modos de fazer adotados por nove jornalistas brasileiros, escolhidos por se submeterem a dois critérios inter-relacionados: 1) serem reconhecidos pelo meio jornalístico e/ou pelo mercado editorial como figuras que se destacam nesse exercício; e 2) terem produzido textos com as características mencionadas para jornais e/ou revistas e que, posteriormente, foram compilados em livro. A metodologia empregada tem vínculo estreito com a perspectiva teórica do newsmaking, valendo-se da técnica apropriada para uma observação que considera diferentes momentos da história (década de 1950 para cá): a entrevista, no seu tipo semiestruturado. O quadro de jornalistas entrevistados é formado por Audálio Dantas, Carlos Wagner, Consuelo Dieguez, Daniela Pinheiro, Eliane Brum, João Moreira Salles, José Hamilton Ribeiro, Ricardo Kotscho e Zuenir Ventura. Como resultado, defendemos que o gênero aqui posto como tema de pesquisa é cultivado por um seleto grupo de profissionais, capazes de direcionar olhares sensíveis sobre a realidade, para dela extrair detalhes e enredos que toquem nos sentimentos dos leitores, divertindo-os, ao propiciar gratificação estética, em contraponto à alienação que se costuma presumir. Trata-se de produção dependente de criatividade e curiosidade, de talento para redigir textos agradáveis e de métodos de apuração e de escrita altamente subjetivos, mas que aparecem como questão bem resolvida no agir profissional desses sujeitos. Essa capacidade também é que os possibilita conquistar espaço, em meio a embates com editores e diretores de redação, para elaborar matérias em que a autoria se sobressai. Por fim, a função de divertir, atribuída ao gênero, é confirmada pelos profissionais, ainda que de modo implícito.

DETERMINAÇÃO DA POSIÇÃO DE REPOUSO DA LÍNGUA EM INDIVÍDUOS COM OCLUSÃO DENTÁRIA NORMAL

O propósito neste estudo foi determinar a posição de repouso da língua em indivíduos com oclusão dentária normal e respiração nasal, por meio de telerradiografias em norma lateral realizadas após a ingestão de bário. A amostra foi composta por 66 radiografias de indivíduos brancos com oclusão dentária normal, sendo 26 do sexo masculino e 40 do sexo feminino, na faixa etária de 12 a 21 anos de idade, procedentes de escolas da região do Grande ABC Paulista. O critério utilizado para diagnóstico da oclusão normal foi As Seis Chaves para a Oclusão Normal preconizadas por Andrews (1972), devendo estar presentes no mínimo quatro das seis chaves, sendo obrigatória a presença da primeira chave de oclusão que é a da relação interarcos. As radiografias foram obtidas com o indivíduo em posição natural da cabeça após a ingestão de contraste de sulfato de bário para evidenciar o controle da língua. Posteriormente foi feito o desenho anatômico das estruturas pesquisadas, marcados os pontos cefalométricos, traçadas as linhas e os planos, e por último obtidas as seguintes medidas lineares: comprimento e altura da língua, distância do dorso da língua na sua porção média até o palato duro e a distância entre a ponta da língua e a incisal do incisivo inferior. Por meio dos resultados encontrados verificou-se que não existe um padrão único de posicionamento de repouso da língua dentro da cavidade oral, em pacientes respiradores nasais, variando muito sua distância até a incisal dos incisivos inferiores, bem como até o palato duro, havendo uniformidade apenas no fato da língua tocar o palato mole em todos os indivíduos da amostra. Não houve relação estatisticamente significante entre a posição de repouso da língua e os biotipos faciais e nem dimorfismo sexual.

Depth propagation and surface construction in 3-D vision

Motion discontinuities can signal object boundaries where few or no other cues, such as luminance, colour, or texture, are available. Hence, motion-defined contours are an ecologically important counterpart to luminance contours. We developed a novel motion-defined Gabor stimulus to investigate the nature of neural operators analysing visual motion fields in order to draw parallels with known luminance operators. Luminance-defined Gabors have been successfully used to discern the spatial-extent and spatial-frequency specificity of possible visual contour detectors. We now extend these studies into the motion domain. We define a stimulus using limited-lifetime moving dots whose velocity is described over 2-D space by a Gabor pattern surrounded by randomly moving dots. Participants were asked to determine whether the orientation of the Gabor pattern (and hence of the motion contours) was vertical or horizontal in a 2AFC task, and the proportion of correct responses was recorded. We found that with practice participants became highly proficient at this task, able in certain cases to reach 90% accuracy with only 12 limited-lifetime dots. However, for both practised and novice participants we found that the ability to detect a single boundary saturates with the size of the Gaussian envelope of the Gabor at approximately 5 deg full-width at half-height. At this optimal size we then varied spatial frequency and found the optimum was at the lowest measured spatial frequency (0.1 cycle deg-1 ) and then steadily decreased with higher spatial frequencies, suggesting that motion contour detectors may be specifically tuned to a single, isolated edge.

Edges and bars: where do people see features in 1-D images?

There have been two main approaches to feature detection in human and computer vision - based either on the luminance distribution and its spatial derivatives, or on the spatial distribution of local contrast energy. Thus, bars and edges might arise from peaks of luminance and luminance gradient respectively, or bars and edges might be found at peaks of local energy, where local phases are aligned across spatial frequency. This basic issue of definition is important because it guides more detailed models and interpretations of early vision. Which approach better describes the perceived positions of features in images? We used the class of 1-D images defined by Morrone and Burr in which the amplitude spectrum is that of a (partially blurred) square-wave and all Fourier components have a common phase. Observers used a cursor to mark where bars and edges were seen for different test phases (Experiment 1) or judged the spatial alignment of contours that had different phases (e.g. 0 degrees and 45 degrees ; Experiment 2). The feature positions defined by both tasks shifted systematically to the left or right according to the sign of the phase offset, increasing with the degree of blur. These shifts were well predicted by the location of luminance peaks (bars) and gradient peaks (edges), but not by energy peaks which (by design) predicted no shift at all. These results encourage models based on a Gaussian-derivative framework, but do not support the idea that human vision uses points of phase alignment to find local, first-order features. Nevertheless, we argue that both approaches are presently incomplete and a better understanding of early vision may combine insights from both. (C)2004 Elsevier Ltd. All rights reserved.

Effects of the rate of formant-frequency variation on the grouping of formants in speech perception

How speech is separated perceptually from other speech remains poorly understood. Recent research suggests that the ability of an extraneous formant to impair intelligibility depends on the modulation of its frequency, but not its amplitude, contour. This study further examined the effect of formant-frequency variation on intelligibility by manipulating the rate of formant-frequency change. Target sentences were synthetic three-formant (F1?+?F2?+?F3) analogues of natural utterances. Perceptual organization was probed by presenting stimuli dichotically (F1?+?F2C?+?F3C; F2?+?F3), where F2C?+?F3C constitute a competitor for F2 and F3 that listeners must reject to optimize recognition. Competitors were derived using formant-frequency contours extracted from extended passages spoken by the same talker and processed to alter the rate of formant-frequency variation, such that rate scale factors relative to the target sentences were 0, 0.25, 0.5, 1, 2, and 4 (0?=?constant frequencies). Competitor amplitude contours were either constant, or time-reversed and rate-adjusted in parallel with the frequency contour. Adding a competitor typically reduced intelligibility; this reduction increased with competitor rate until the rate was at least twice that of the target sentences. Similarity in the results for the two amplitude conditions confirmed that formant amplitude contours do not influence across-formant grouping. The findings indicate that competitor efficacy is not tuned to the rate of the target sentences; most probably, it depends primarily on the overall rate of frequency variation in the competitor formants. This suggests that, when segregating the speech of concurrent talkers, differences in speech rate may not be a significant cue for across-frequency grouping of formants.

Posterior retinal contour in adult human anisomyopia

PURPOSE. It is well documented that myopia is associated with an increase in axial length or, more specifically, in vitreous chamber depth. Whether the transverse dimensions of the eye also increase in myopia is relevant to further understanding of its development. METHODS. The posterior retinal surface was localized in two-dimensional space in both eyes of young adult white and Taiwanese-Chinese iso- and anisomyopes (N = 56), from measured keratometry, A-scan ultrasonography, and central and peripheral refraction (±35°) data, with the aid of a computer modeling program designed for this purpose. Anisomyopes had 2 D or more interocular difference in their refractive errors, with mean values in their more myopic eyes of -5.57 D and in their less myopic eyes of -3.25 D, similar to the means of the two isomyopic groups. The derived retinal contours for the more and less myopic eyes were compared by way of investigating ocular shape changes that accompany myopia, in the posterior region of the vitreous chamber. The presence and size of optic disc crescents were also investigated as an index of retinal stretching in myopia. RESULTS. Relative to the less myopic eyes of anisometropic subjects, the more myopic eyes were more elongated and also distorted into a more prolate shape in both the white and Chinese groups. However, the Chinese eyes showed a greater and more uniform relative expansion of the posterior retinal surface in their more myopic eyes, and this was associated with larger optic disc crescents. The changes in the eyes of whites displayed a nasal-temporal axial asymmetry, reflecting greater enlargement of the nasal retinal sector. CONCLUSIONS. Myopia is associated with increased axial length and a prolate shape. This prolate shape is consistent with the proposed idea that axial and transverse dimensions of the eye are regulated differently. The observations that ocular shape changes are larger but more symmetrical in Chinese eyes than in eyes of whites warrant further investigation.

Effects of differences in fundamental frequency on across-formant grouping in speech perception

In an isolated syllable, a formant will tend to be segregated perceptually if its fundamental frequency (F0) differs from that of the other formants. This study explored whether similar results are found for sentences, and specifically whether differences in F0 (?F0) also influence across-formant grouping in circumstances where the exclusion or inclusion of the manipulated formant critically determines speech intelligibility. Three-formant (F1 + F2 + F3) analogues of almost continuously voiced natural sentences were synthesized using a monotonous glottal source (F0 = 150 Hz). Perceptual organization was probed by presenting stimuli dichotically (F1 + F2C + F3; F2), where F2C is a competitor for F2 that listeners must resist to optimize recognition. Competitors were created using time-reversed frequency and amplitude contours of F2, and F0 was manipulated (?F0 = ±8, ±2, or 0 semitones relative to the other formants). Adding F2C typically reduced intelligibility, and this reduction was greatest when ?F0 = 0. There was an additional effect of absolute F0 for F2C, such that competitor efficacy was greater for higher F0s. However, competitor efficacy was not due to energetic masking of F3 by F2C. The results are consistent with the proposal that a grouping “primitive” based on common F0 influences the fusion and segregation of concurrent formants in sentence perception.

The intelligibility of noise-vocoded speech:spectral information available from across-channel comparison of amplitude envelopes

Noise-vocoded (NV) speech is often regarded as conveying phonetic information primarily through temporal-envelope cues rather than spectral cues. However, listeners may infer the formant frequencies in the vocal-tract output—a key source of phonetic detail—from across-band differences in amplitude when speech is processed through a small number of channels. The potential utility of this spectral information was assessed for NV speech created by filtering sentences into six frequency bands, and using the amplitude envelope of each band (=30 Hz) to modulate a matched noise-band carrier (N). Bands were paired, corresponding to F1 (˜N1 + N2), F2 (˜N3 + N4) and the higher formants (F3' ˜ N5 + N6), such that the frequency contour of each formant was implied by variations in relative amplitude between bands within the corresponding pair. Three-formant analogues (F0 = 150 Hz) of the NV stimuli were synthesized using frame-by-frame reconstruction of the frequency and amplitude of each formant. These analogues were less intelligible than the NV stimuli or analogues created using contours extracted from spectrograms of the original sentences, but more intelligible than when the frequency contours were replaced with constant (mean) values. Across-band comparisons of amplitude envelopes in NV speech can provide phonetically important information about the frequency contours of the underlying formants.

The perceptual organization of sine-wave speech under competitive conditions

Speech comprises dynamic and heterogeneous acoustic elements, yet it is heard as a single perceptual stream even when accompanied by other sounds. The relative contributions of grouping “primitives” and of speech-specific grouping factors to the perceptual coherence of speech are unclear, and the acoustical correlates of the latter remain unspecified. The parametric manipulations possible with simplified speech signals, such as sine-wave analogues, make them attractive stimuli to explore these issues. Given that the factors governing perceptual organization are generally revealed only where competition operates, the second-formant competitor (F2C) paradigm was used, in which the listener must resist competition to optimize recognition [Remez et al., Psychol. Rev. 101, 129-156 (1994)]. Three-formant (F1+F2+F3) sine-wave analogues were derived from natural sentences and presented dichotically (one ear = F1+F2C+F3; opposite ear = F2). Different versions of F2C were derived from F2 using separate manipulations of its amplitude and frequency contours. F2Cs with time-varying frequency contours were highly effective competitors, regardless of their amplitude characteristics. In contrast, F2Cs with constant frequency contours were completely ineffective. Competitor efficacy was not due to energetic masking of F3 by F2C. These findings indicate that modulation of the frequency, but not the amplitude, contour is critical for across-formant grouping.

Axis-based grouping reduces visual extinction

We examined the effects on extinction of grouping by collinearity of edges and grouping by alignment of internal axes of shapes, in a patient (GK) with simultanagnosia following bilateral parietal brain damage. GK’s visual extinction was reduced when items (equilateral triangles and angles) could be grouped by base alignment (i.e., collinearity) or by axis alignment, relative to a condition in which items were ungrouped. These grouping effects disappeared when inter-item spacing was increased, though factors such as display symmetry remained constant. Overall, the results suggest that, under some conditions, grouping by alignment of axes of symmetry can have an equal beneficial effect on visual extinction as edge-based grouping; thus, in the extinguished field, there is derivation of axis-based representations from the contours present.

Remembrance of things past:the lingering impact of history on contemporary Polish-Ukrainian relations

This article investigates the continuing influence of the past on contemporary politics in Poland and Ukraine by examining the impact of the vocal 'informed' segment of public opinion on mutual relations between the two countries. The section 'What history?' examines the question of exactly what understanding of history matters so much in Polish-Ukrainian relations. The following sections examine how history influences the present, what are the contours of public opinion on Polish-Ukrainian relations within each state, and what is the impact of shared history on the contemporary politics of Polish-Ukrainian relations. Finally, the article suggests a potentially generaliseable hypothesis for future research.