Let H be a separable Hilbert space and {e_n : n belong to Z} be an orthonormal basis in H. A bounded operator T is called the slant Toeplitz operator if <T ej , ei> =c2i−j , where c_n is the n-th Fourier series of a bounded Lebesgue measurable function on the unit circle T = {z belong to C : |z| = 1}. It has been shown [7] that T* is an isometry if and only if |fi(z)|^2 +|fi(−z)|^2 = 2 a.e. on T and if this is the case and fi belong to C(T), then either T is unitarily equivalent to a shift or to the direct sum of a shift and a rank one unitary, with infinite multiplicity (for the shift part, that is). Moreover, with some additional assumption on the smoothness and the zeros of fi, T* is similar to either the constant multiple of a shift or to the constant multiple of the direct sum of a shift and a rank one unitary, with infinite multiplicity. On the other hand, according to the terminologies in [10], an operator A that is constant with respect to a shift S if AS = SA and A S = SA . Therefore, in this article, we will study the operators that is constant with respect to T , i.e., bounded operator A satisfying AT = T A and A T = T A .

Experiments were carried out to study the effect of workmanship and environmental conditions on bond strength for concrete patch repairs. Four repair materials, sand/cement mortar, acrylic modified cementitious mortar, SBR modified cementitious mortar, and flowing concrete, were tested with mainly three test methods (core pull-off test, patch compressive test, and patch flexural test). At the beginning of this project, slant shear tests were also carried out. In the study of the effect of workmanship, the following parameters were included: surface roughness, surface cleanliness, surface soundness, moisture condition, application method, bond coat mistiming, repair material mistiming, and curing methods. In the study of the effect of environmental conditions, four parameters were considered: high temperature curing followed by drying shrinkage, high temperature curing followed by thermal cycling, low temperature curing, and low temperature curing followed by freeze/thaw cycling. A rougher surface produces a higher bond strength, but the increase depends on individual repair material. Sand/cement mortar favours a rough surface, but polymer modified mortars are not very sensitive to surface roughness. Environmental conditions affect the bond strength development, but the effect varies with each repair material. Test results suggest that low temperature curing should be avoided for polymer modified cementitious mortars. In addition to the experimental study, theoretical analyses were carried out to evaluate the available bond test methods. The evaluation was concentrated on answering the following questions: (1) What kind of factors will influence conductinga bond test? (2) What are the response of each factor involved to a specific test method? (3) What kind of influences are crucial in ensuring the full development of the bond strength? (4) Which factors are important to achieve a durable repair? and (5) What kind of a test can be used to monitor the quality of these crucial factors? In total, about 800 tests were conducted (500 core pull-off tests, 90 patch compressive tests, 100 patch flexural tests, and 80 slant shear tests).

This framing analysis used content analysis to show how a newspaper with a more liberal slant, The Age, and a newspaper with a more conservative slant, The Australian, used frames, sources, and valence in their news and opinion coverage of a very complex scientific and political issue ? climate change. The sample included 1,019 news and opinion articles from 1997 through 2007 in The Australian and The Age. The study revealed that the controversy over climate change was still prevalent in two Australian newspapers. Results showed that The Australian and The Age displayed different prominent frames, sources, and valence in their climate change coverage. Overall, The Australian was more critical and uncertain about climate change, while The Age aimed to educate its readers about the background of the issue and inspire action.

Let $l^2(Bbb Z)$ be the Hilbert space of square summable double sequences of complex numbers with standard basis ${e_n:ninBbb Z}$, and let us consider a bounded matrix $A$ on $l^2(Bbb Z)$ satisfying the following system of equations egin{itemize} item[1.] $lan Ae_{2j},e_{2i} an=p_{ij}+alan Ae_{j},e_i an$; item[2.] $lan Ae_{2j},e_{2i-1} an=q_{ij}+blan Ae_{j},e_{i} an$; item[3.] $lan Ae_{2j-1},e_{2i} an=v_{ij}+clan Ae_{j},e_{i} an$; item[4.] $lan Ae_{2j-1},e_{2i-1} an=w_{ij}+dlan Ae_{j},e_{i} an$ end{itemize} for all $i,j$, where $P=(p_{ij})$, $Q=(q_{ij})$, $V=(v_{ij})$, $W=(w_{ij})$ are bounded matrices on $l^2(Bbb Z)$ and $a,b,c,dinBbb C$. This type dyadic recurrent system arises in the study of bounded operators commuting with the slant Toeplitz operators, i.e., the class of operators ${{cal T}_vp:vpin L^infty(Bbb T)}$ satisfying $lan {cal T}_vp e_j,e_i an=c_{2i-j}$, where $c_n$ is the $n$-th Fourier coefficient of $vp$. It is shown in [10] that the solutions of the above system are closely related to the bounded solution $A$ for the operator equation [ phi(A)=S^*AS=lambda A+B, ] where $B$ is fixed, $lambdainBbb C$ and $S$ the shift given by ${cal T}_{arzeta+arxi z}^*$ (with $zetaxi ot=0$ and $|zeta|^2+|xi|^2=1$). In this paper, we shall characterize the ``eigenvectors" for $phi$ for the eigenvalue $lambda$ with $|lambda|leq1$, in terms of dyadic recurrent systems similar to the one above.

Good bond strength between overlay and substrate is a key factor in performance of concrete repairs. This thesis was aimed at studying the evaluation of bond strength between repair material and substrate at the interface. Many factors such as surface roughness, existence of micro cracks, compaction, curing etc influence the bond strength. The quality assurance of the bond strength requires test methods that can quantify the bond strength as well as identify the failure mode. There have been numerous investigations led to development of different test methods. The forces which are applied in each test and the failure mode are important in order to choose the proper test. An interpretive study on test methods is presented. While this study can provide individually useful information on bond strength and bond characterization, it also contains discussions about each test and comparison of test methods.

Handwriting difficulties affect 10% to 30% of children in elementary school often hindering their successful participation in a number of occupations, including academic participation. Occupational therapists provide treatments for handwriting difficulties; however, many of these interventions have limited to no evidence to support their effectiveness. One of these interventions is the use of a slant board, a treatment strategy often combined with handwriting practice. Clinicians commonly combine the use of slant boards and handwriting practice to facilitate the development of handwriting skills in young children. However, the effectiveness of this combination of interventions in improving the quality of handwriting remains unclear. The aim of this study was to investigate the difference in the change of letter formation scores in children who have practiced handwriting on slant boards compared with those who have practiced on a horizontal surface. A randomized block design was employed. Children entering the second through third grades who participated in a 19-day summer enrichment program were recruited via mailed recruitment letters and/or email. Twenty-one children were enrolled. Children were blocked by classroom and randomly assigned to a group that practiced handwriting on a slant board or a group that practiced on a horizontal surface. Children completed a total of 15 group sessions lasting 15 minutes each. These sessions occurred 3 to 5 days a week over the course of 4 weeks. During these sessions, they practiced writing letters and words utilizing the Handwriting Without Tears curriculum. There was no significant difference in average group change in letter formation performance as determined by independent samples t test. Children with below average handwriting at baseline made statistically significant changes in their handwriting, regardless of writing surface, when compared with their peers that was identified by secondary analyses.

No / When a planar object is rotated with respect to a directional light source, the reflected luminance changes. If surface lightness is to be a reliable guide to surface identity, observers must compensate for such changes. To the extent they do, observers are said to be lightness constant. We report data from a lightness matching task that assesses lightness constancy with respect to changes in object slant. On each trial, observers viewed an achromatic standard object and indicated the best match from a palette of 36 grayscale samples. The standard object and the palette were visible simultaneously within an experimental chamber. The chamber illumination was provided from above by a theater stage lamp. The standard objects were uniformly-painted flat cards. Different groups of naïve observers made matches under two sets of instructions. In the Neutral Instructions, observers were asked to match the appearance of the standard and palette sample. In the Paint Instructions, observers were asked to choose the palette sample that was painted the same as the standard. Several broad conclusions may be drawn from the results. First, data for most observers were neither luminance matches nor lightness constant matches. Second, there were large and reliable individual differences. To characterize these, a constancy index was obtained for each observer by comparing how well the data were accounted for by both luminance matching and lightness constancy. The index could take on values between 0 (luminance matching) and 1 (lightness constancy). Individual observer indices ranged between 0.17 and 0.63 with mean 0.40 and median 0.40. An auxiliary slant-matching experiment rules out variation in perceived slant as the source of the individual variability. Third, the effect of instructions was small compared to the inter-observer variability. Implications of the data for models of lightness perception are discussed.

No / In the companion study (C. Ripamonti et al., 2004), we present data that measure the effect of surface slant on perceived lightness. Observers are neither perfectly lightness constant nor luminance matchers, and there is considerable individual variation in performance. This work develops a parametric model that accounts for how each observer¿s lightness matches vary as a function of surface slant. The model is derived from consideration of an inverse optics calculation that could achieve constancy. The inverse optics calculation begins with parameters that describe the illumination geometry. If these parameters match those of the physical scene, the calculation achieves constancy. Deviations in the model¿s parameters from those of the scene predict deviations from constancy. We used numerical search to fit the model to each observer¿s data. The model accounts for the diverse range of results seen in the experimental data in a unified manner, and examination of its parameters allows interpretation of the data that goes beyond what is possible with the raw data alone.

No description available.

Grâce à l'optimisation de l'effet TWIP (Twinning Induced Plasticity) et à la maîtrise de la microstructure (basse énergie de défaut d'empilement, austénite stable à grains fins), les aciers austénitiques Fe-Mn-C combinent une excellente ductilité à une résistance mécanique élevée. L'étude s'intéresse aux paramètres mécaniques critiques menant à la rupture ductile en mode slant (biseau dans l'épaisseur) et aux aspects physiques de l'endommagement dans le but de déterminer un critère de rupture quantitatif. Le comportement plastique de l'acier TWIP présente un caractère anisotrope et cinématique avec une déformation hétérogène en traction uniaxiale due à un mécanisme de pseudo-vieillissement dynamique. Après avoir déterminé la loi de comportement, la courbe limite de formage a pu être établie par comparaison entre résultats expérimentaux et prédictions du modèle mécanique, dans une large gamme de triaxialité des contraintes. Quel que soit le mode de déformation considéré, la rupture s'effectue brutalement en mode slant sans striction localisée. Peu d'endommagement, y compris en trois dimensions, a été observé autour des zones de rupture. Un critère de rupture phénoménologique basé sur la contrainte équivalente et sur l'angle de Lode, redéfinis tous deux dans l'équivalent de Barlat, permet de prédire de façon correcte la formabilité de l'acier TWIP. L'influence de la pression hydrostatique et du mécanisme de pseudo vieillissement dynamique sur la courbe limite de formage est discutée.