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1.
Heliyon ; 9(10): e20469, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37810848

RESUMO

In order to realize the high-precision assembly of the mirror of the aeronautical optical system, a semi-kinematic flexible support structure applied to the airborne field was designed. This paper studies the support principle and assembly method of flexible support of mirror. Firstly, according to the kinematic theory of space mechanism, the spatial degrees of freedom of the mirror were theoretically analyzed. Then, in view of the difficulties encountered in the assembly and application of the mirror, a flexible support structure was designed. Then, the design results were verified by means of finite element analysis. Finally, the processing and assembly of a flexible support structure of the mirror was completed, and the relevant experimental tests were carried out. The experimental results show that the accuracy of the mirror after assembly with flexible support structure is better than λ/50 (λ = 632.8 nm), and the mass is less than 2 kg. The model fundamental frequency modal of the whole assembly is 645 Hz, which is higher than the design requirement. All simulation and test results show that the flexible support structure works well, meets the requirements of aviation optical system, and has the advantages of simple assembly, high precision, stability and reliability.

2.
Clin Exp Optom ; 106(5): 476-483, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-35614035

RESUMO

CLINICAL RELEVANCE: Inter-instrument variation in anterior corneal shape (ACS) measurement has a consequence for ocular clinical practice. BACKGROUND: To consider inter-instrument variability in keratometry measurements across the ACS and to explore instrument protocols for determining ACS keratometric analogues (KAs). METHODS: Mean keratometry/KAs of the right eye were recorded using Javal-Schiøtz keratometer (J-S), Orbscan IIz and Pentacam from 124 subjects (78 females; mean ± SD age: 24.71 ± 6.61 years). Mean radii of curvature were obtained for 1-mm wide annular zones extending up to 6 mm (horizontally) and 4 mm (vertically) from the apex for Orbscan and Pentacam. Zonal mean radius of curvature was calculated by averaging keratometry values for all measured points within the zone. RESULTS: KA (mean ± SD): Horizontal: Orbscan (7.80 ± 0.31 mm) and J-S (7.82 ± 0.29 mm) were not significantly different (p = 0.072). Pentacam (7.86 ± 0.29 mm) was significantly flatter than J-S (p < 0.001) and Orbscan (p < 0.001). Vertical: Orbscan (7.64 ± 0.31 mm) was significantly steeper than J-S (7.67 ± 0.29 mm, p < 0.005) and Pentacam (7.70 ± 0.29 mm, p < 0.001). Pentacam was significantly flatter than J-S (p < 0.001) and significant flatter than Orbscan across the entire profile (1-4 mm zones horizontal and vertical, p < 0.001).                        LoAs (CI): J-S/Orbscan: ±0.75 mm (0.05-0.18); J-S/Pentacam: ±0.72 mm (0.01-0.12); Pentacam/Orbscan: ±0.16 mm (0.04-0.08). There was a +0.03 mm positive bias for Orbscan compared to J-S, +0.06 mm positive bias for Orbscan compared to Pentacam and -0.03 mm negative bias for Pentacam compared to J-S. CONCLUSIONS: Algorithms used by Orbscan and Pentacam to solve the peripheral paraxial ray problem produce significantly different KAs. Instrument-specific KAs cannot be used inter-changeably between instruments. Differences in KA between instruments are not significant for ocular surgery, but may influence rigid contact lens fitting. Pentacam measures flatter than Orbscan and J-S.


Assuntos
Lentes de Contato , Córnea , Feminino , Humanos , Adolescente , Adulto Jovem , Adulto , Topografia da Córnea/métodos , Estudos Prospectivos , Córnea/diagnóstico por imagem , Reprodutibilidade dos Testes
3.
Front Plant Sci ; 13: 999304, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36340340

RESUMO

Understanding plant development is in part a theoretical endeavor that can only succeed if it is based upon a correctly contrived axiomatic framework. Here I revisit some of the basic assumptions that frame our understanding of plant development and suggest that we consider an alternative informational ecosystem that more faithfully reflects the physical and architectural realities of plant tissue and organ growth. I discuss molecular signaling as a stochastic process and propose that the iterative and architectural nature of plant growth is more usefully represented by deterministic models based upon structural, surficial, and stress-mechanical information networks that come into play at the trans-cellular level.

4.
Micromachines (Basel) ; 13(7)2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35888877

RESUMO

Magnetic field assisted finishing (MFAF) technology has been widely used in industries such as aerospace, biomedical, and the optical field for both external and internal surface finishing due to its high conformability to complex surfaces and nanometric surface finishing. However, most of the MFAF methods only allow polishing piece-by-piece, leading to high post-processing costs and long processing times with the increasing demand for high precision products. Hence, a magnetic field-assisted mass polishing (MAMP) method was recently proposed, and an experimental investigation on the effect of surface posture is presented in this paper. Two groups of experiments were conducted with different workpiece shapes, including the square bar and roller bar, to examine the effect of surface orientation and polishing performance on different regions. A simulation of magnetic field distribution and computational fluid dynamics was also performed to support the results. Experimental results show that areas near the chamber wall experience better polishing performance, and the surface parallel or inclined to polishing direction generally allows better shearing and thus higher polishing efficiency. Both types of workpieces show notable polishing performance where an 80% surface roughness improvement was achieved after 20-min of rough polishing and 20-min of fine polishing reaching approximately 20 nm.

5.
J Voice ; 2022 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-35410779

RESUMO

OBJECTIVES: Voice production in pathological conditions or after surgical intervention often involves undesired medial surface shape such as reduced vertical thickness and/or left-right asymmetry in medial surface shape. The effect of such undesired medial surface on voice production remains unclear, and is often not taken into consideration during planning of surgical intervention, due to difficulty of imaging the medial surface in patients. This study aims to better understand how voice outcomes are impacted by undesired medial surface shape. METHODS: Computational simulations were conducted to parametrically manipulate medial surface shape and stiffness and observe its consequence on voice production. RESULTS: The results showed that undesired medial surface shape can result in incomplete glottal closure, weak voice production, increased phonation threshold, and significantly reduced vocal efficiency, particularly in the presence of left-right stiffness asymmetry. CONCLUSIONS: In addition to approximating the vocal folds, medialization laryngoplasty should additionally aim to sufficiently increase medial surface thickness, which may improve voice outcomes in patients whose voices remain unsatisfactory or suboptimal after initial intervention. While a divergent implant may increase medial surface thickness, precise implant placement in anticipation of tissue and implant deformation during the insertion process is equally important in order to achieve desired medial surface shape and optimal voice outcomes.

6.
AMB Express ; 12(1): 9, 2022 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-35102449

RESUMO

Fine particle bombarding (FPB) is typically utilized to modify metal surfaces by bombarding them with fine particles at high-speed. The diameters of the particles range from several to tens of micrometers. FPB forms fine microscale concavities and convexities on a surface. As FPB-treated surfaces are widely used in the food industry, the influence of bacteria on their surface must be considered. In this study, we examined the antibacterial activity of microscale rough surfaces formed by FPB. We applied FPB to a stainless-steel surface and evaluated the antibacterial effect of FPB-treated surfaces based on JIS Z 2801 (a modified test method from ISO 22196:2007). Our results indicated that the FPB-treated surfaces (FPB-1 (avg. pitch: 0.72 µm) and FPB-2 (avg. pitch: 3.56 µm)) exhibited antibacterial activity both against Escherichia coli and Staphylococcus aureus.

7.
Cont Lens Anterior Eye ; 44(2): 270-288, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33775380

RESUMO

Scleral lenses were the first type of contact lens, developed in the late nineteenth century to restore vision and protect the ocular surface. With the advent of rigid corneal lenses in the middle of the twentieth century and soft lenses in the 1970's, the use of scleral lenses diminished; in recent times there has been a resurgence in their use driven by advances in manufacturing and ocular imaging technology. Scleral lenses are often the only viable form of contact lens wear across a range of clinical indications and can potentially delay the need for corneal surgery. This report provides a brief historical review of scleral lenses and a detailed account of contemporary scleral lens practice including common indications and recommended terminology. Recent research on ocular surface shape is presented, in addition to a comprehensive account of modern scleral lens fitting and on-eye evaluation. A range of optical and physiological challenges associated with scleral lenses are presented, including options for the clinical management of a range of ocular conditions. Future applications which take advantage of the stability of scleral lenses are also discussed. In summary, this report presents evidence-based recommendations to optimise patient outcomes in modern scleral lens practice.


Assuntos
Lentes de Contato , Esclera , Córnea , Humanos , Ajuste de Prótese , Acuidade Visual
8.
Work ; 66(1): 161-171, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32417823

RESUMO

BACKGROUND: Students remain in a sedentary position inside classrooms for 60% to 80% of their school day. As such, research has associated students' prolonged seated posture on school furniture with their discomfort and musculoskeletal pain. The correlation between the shape of the seat surface and the zones of the body making contact with these surfaces constitutes an essential factor in determining comfort-enhancing seat design. OBJECTIVE: This study's primary aim lies in contrasting the standard, current school chair against two seat prototypes, both designed and built from digital models, comparing seat-user pressure distribution and contact area during students' performance of different school tasks. METHODS: Participants (n = 13), ages 7 to 19, performed school tasks sitting on three different chairs' seat surfaces during the test: the current seat used in schools and two seat prototypes, each designed based on body anatomy. The seats were evaluated through a force-sensing array pressure-mapping system. RESULTS: The measurements from designed seat prototypes provide a better distribution of pressures and greater contact area with the students' anatomical areas (buttocks and thighs) than the seat currently used in the specified schools. The improvement in pressure values and contact area as seen in the second designed seat prototype is due to its inclination angle and contact with students' sacral zone. CONCLUSIONS: This research work found that a seat's shape based on human anatomical features (buttocks and thighs), compared to a completely flat seat, creates a higher reduction of body pressures and an increase in the body contact area, with the intent to increase comfort and reduce musculoskeletal pain.


Assuntos
Nádegas , Decoração de Interiores e Mobiliário , Pressão , Coxa da Perna , Adolescente , Criança , Desenho de Equipamento , Ergonomia , Feminino , Humanos , Masculino , Postura Sentada , Estudantes , Adulto Jovem
9.
Epilepsia ; 61(4): 735-746, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32196657

RESUMO

OBJECTIVE: To examine the shared familial contribution to hippocampal and extrahippocampal morphological abnormalities in patients with sporadic temporal lobe epilepsy (TLE) and their unaffected siblings. METHODS: We collected clinical, electrophysiological, and T1-weighted magnetic resonance imaging (MRI) data of 18 sporadic patients with TLE without lesions other than hippocampal sclerosis (12 right, 6 left), their 18 unaffected full siblings, and 18 matched healthy volunteers. We compared between-group differences in cortical thickness and volumes of five subcortical areas (hippocampus, amygdala, thalamus, putamen, and pallidum). We determined the subregional extent of hippocampal abnormalities using surface shape analysis. All our imaging results were corrected for multiple comparisons using random field theory. RESULTS: We detected smaller hippocampal volumes in patients (right TLE: median right hippocampus 1.92 mL, interquartile range [IQR] 1.39-2.62, P < .001; left TLE: left hippocampus 2.05 mL, IQR 1.99-2.33, P = .01) and their unaffected siblings (right hippocampus 2.65 mL, IQR 2.32-2.80, P < .001; left hippocampus 2.39 mL, IQR 2.18-2.53, P < .001) compared to healthy controls (right hippocampus 2.94 mL, IQR 2.77-3.24; left hippocampus 2.71 mL, IQR 2.37-2.89). Surface shape analysis showed that patients with TLE had bilateral subregional atrophy in both hippocampi (right > left). Similar but less-pronounced subregional atrophy was detected in the right hippocampus of unaffected siblings. Patients with TLE had reduced cortical thickness in bilateral premotor/prefrontal cortices and the right precentral gyrus. Siblings did not show abnormalities in cortical or subcortical areas other than the hippocampus. SIGNIFICANCE: Our results demonstrate a shared vulnerability of the hippocampus in both patients with TLE and their unaffected siblings, pointing to a contribution of familial factors to hippocampal atrophy. This neuroimaging trait could represent an endophenotype of TLE, which might precede the onset of epilepsy in some individuals.


Assuntos
Epilepsia do Lobo Temporal/patologia , Hipocampo/anormalidades , Hipocampo/patologia , Irmãos , Adulto , Atrofia/patologia , Feminino , Humanos , Masculino
10.
Beilstein J Nanotechnol ; 10: 1157-1165, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31293853

RESUMO

A mild and simple method was developed to synthesize a highly efficient photocatalyst comprised of Ce-doped ZnO rods and optimal synthesis conditions were determined by testing samples with different Ce/ZnO molar ratios calcined at 500 °C for 3 hours via a one-step pyrolysis method. The photocatalytic activity was assessed by the degradation of a common dye pollutant found in wastewater, rhodamine B (RhB), using a sunlight simulator. The results showed that ZnO doped with 3% Ce exhibits the highest RhB degradation rate. To understand the crystal structure, elemental state, surface morphology and chemical composition, the photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and inductively coupled plasma emission spectroscopy (ICP), respectively. The newly developed, robust, field-only surface integral method was employed to explore the relationship between the remarkable catalytic effect and the catalyst shape and porous microstructure. The computational results showed that the dipole-like field covers the entire surface of the rod-like Ce-doped ZnO photocatalyst and is present over the entire range of wavelengths considered. The optimum degradation conditions were determined by orthogonal tests and range analysis, including the concentration of RhB and catalyst, pH value and temperature. The results indicate that the pH value is the main influential factor in the photocatalytic degradation process and the optimal experimental conditions to achieve the maximum degradation rate of 97.66% in 2 hours are as follows: concentration (RhB) = 10 mg/L, concentration (catalyst) = 0.7 g/L, pH 9.0 and T = 50 °C. These optimum conditions supply a helpful reference for large-scale wastewater degradation containing the common water contaminant RhB.

11.
J Voice ; 31(4): 513.e15-513.e23, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28089390

RESUMO

OBJECTIVES/HYPOTHESIS: Glottal insufficiency is a common clinical problem in otolaryngology and medialization laryngoplasty (ML) procedures remain the primary treatment modality. Although the goal of ML is to restore physiologic glottal posture and achieve optimal phonation, this posture has not been directly measured. In this study, we assessed glottal medial surface contour changes with selective activation of the intrinsic laryngeal muscles (ILMs). STUDY DESIGN: Basic science study using an in vivo canine hemilarynx model. METHODS: In an in vivo canine hemilarynx, India ink was used to mark fleshpoints in a grid-like fashion along the medial surface of the vocal fold and ILMs were activated in a graded manner. A right-angled prism provided two views of the medial surface, which were recorded using a high-speed camera and used to reconstruct the 3D posture deformations of the medial surface. RESULTS: Thyroarytenoid (TA) muscle activation results in initial inferomedial bulging and increased glottal channel thickness and then glottal adduction with a final rectangular glottal channel shape. Lateral cricoarytenoid (LCA) activation closes the posterior glottis but final posture remains slightly convergent. Together, TA + LCA forms a rectangular glottis with an increased glottal vertical thickness. Posterior cricoarytenoid activation results in abduction and a slightly divergent glottis, whereas cricothyroid activation elongates the glottis and reduces the glottal channel vertical thickness. CONCLUSIONS: A quantitative analysis of in vivo canine vocal fold medial surface upon activation of selective ILMs is provided. This may guide our therapeutic efforts during medialization laryngoplasty, as well as computational modeling of laryngeal physiology.


Assuntos
Músculos Laríngeos/fisiologia , Prega Vocal/fisiologia , Animais , Cães , Técnicas In Vitro , Músculos Laríngeos/diagnóstico por imagem , Prega Vocal/diagnóstico por imagem
12.
Proteins ; 84(7): 979-89, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27038080

RESUMO

Protein-DNA bindings are critical to many biological processes. However, the structural mechanisms underlying these interactions are not fully understood. Here, we analyzed the residues shape (peak, flat, or valley) and the surrounding environment of double-stranded DNA-binding proteins (DSBs) and single-stranded DNA-binding proteins (SSBs) in protein-DNA interfaces. In the results, we found that the interface shapes, hydrogen bonds, and the surrounding environment present significant differences between the two kinds of proteins. Built on the investigation results, we constructed a random forest (RF) classifier to distinguish DSBs and SSBs with satisfying performance. In conclusion, we present a novel methodology to characterize protein interfaces, which will deepen our understanding of the specificity of proteins binding to ssDNA (single-stranded DNA) or dsDNA (double-stranded DNA). Proteins 2016; 84:979-989. © 2016 Wiley Periodicals, Inc.


Assuntos
DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Animais , Sítios de Ligação , DNA/química , DNA de Cadeia Simples/química , Proteínas de Ligação a DNA/química , Bases de Dados de Proteínas , Humanos , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Eletricidade Estática
13.
Q J Exp Psychol (Hove) ; 68(12): 2351-69, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25768675

RESUMO

This study contrasted the role of surfaces and volumetric shape primitives in three-dimensional object recognition. Observers (N = 50) matched subsets of closed contour fragments, surfaces, or volumetric parts to whole novel objects during a whole-part matching task. Three factors were further manipulated: part viewpoint (either same or different between component parts and whole objects), surface occlusion (comparison parts contained either visible surfaces only, or a surface that was fully or partially occluded in the whole object), and target-distractor similarity. Similarity was varied in terms of systematic variation in nonaccidental (NAP) or metric (MP) properties of individual parts. Analysis of sensitivity (d') showed a whole-part matching advantage for surface-based parts and volumes over closed contour fragments--but no benefit for volumetric parts over surfaces. We also found a performance cost in matching volumetric parts to wholes when the volumes showed surfaces that were occluded in the whole object. The same pattern was found for both same and different viewpoints, and regardless of target-distractor similarity. These findings challenge models in which recognition is mediated by volumetric part-based shape representations. Instead, we argue that the results are consistent with a surface-based model of high-level shape representation for recognition.


Assuntos
Atenção , Percepção de Profundidade , Discriminação Psicológica , Reconhecimento Visual de Modelos , Feminino , Humanos , Masculino , Orientação , Mascaramento Perceptivo , Adulto Jovem
14.
Gait Posture ; 41(2): 562-7, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25593008

RESUMO

The purpose of this study was to test the hypothesis that muscle intensity and ankle joint motion will be greater when balancing on a surface shaped like a cobblestone pathway than on a smooth surface. Nineteen healthy male and female subjects participated in this study. Electromyographic (EMG) activity of the soleus, gastrocnemii medialis and lateralis, peroneus longus and tibialis anterior and ankle dorsiflexion/plantarflexion and eversion/inversion were recorded for unilateral balancing tasks on a hard smooth (control), soft smooth and two cobblestone shaped balance surfaces. Mean ankle kinematics did not differ between conditions. EMG intensity of the lower leg muscles were significant lower for the cobblestone shaped surface than for the control surface (-40 to -80%; P<.01). EMG intensity of the lower leg muscles were significantly higher for the soft smooth surface than for the control surface (+12 to +30%; P<.01). Different balance strategies or tendon stretching may be responsible for these differences. Not only material properties but also surface shape of balance surfaces should be considered to optimize training output and tailored to the specific goal of a training regimen.


Assuntos
Articulação do Tornozelo/fisiologia , Perna (Membro)/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Feminino , Humanos , Masculino , Fenômenos Fisiológicos Musculoesqueléticos , Adulto Jovem
15.
Artigo em Inglês | MEDLINE | ID: mdl-24070433

RESUMO

Prevention and treatment of osteoporosis rely on understanding of the micromechanical behaviour of bone and its influence on fracture toughness and cell-mediated adaptation processes. Postyield properties may be assessed by nonlinear finite element simulations of nanoindentation using elastoplastic and damage models. This computational study aims at determining the influence of yield surface shape and damage on the depth-dependent response of bone to nanoindentation using spherical and conical tips. Yield surface shape and damage were shown to have a major impact on the indentation curves. Their influence on indentation modulus, hardness, their ratio as well as the elastic-to-total work ratio is well described by multilinear regressions for both tip shapes. For conical tips, indentation depth was not statistically significant (p < 0.0001). For spherical tips, damage was not a significant parameter (p < 0.0001). The gained knowledge can be used for developing an inverse method for identification of postelastic properties of bone from nanoindentation.


Assuntos
Osso e Ossos/patologia , Osso e Ossos/fisiopatologia , Nanotecnologia , Estresse Mecânico , Elasticidade , Análise de Elementos Finitos , Dureza , Humanos , Análise de Regressão
16.
Braz. j. biol ; 74(4): 803-809, 11/2014. tab, graf
Artigo em Inglês | LILACS | ID: lil-732328

RESUMO

Considering that in previous studies, the surface roughness (micrometric dimension) showed a weak effect on the colonization of stream macroalgae, we investigated the effects of different crevice sizes (milimetric dimension, a scale slightly higher than previous investigations) on the macroalgal abundance in three streams exposed to full sunlight in southern Brazil. We used smooth sterile glass plates with different shapes: P – plane surface without crevices; S – sinuous surface (depth of crevices with 0.159 mm ± 0.03); N – non-unifom surface (0.498 mm ± 0.09); C – surfaces with convex structures (1.190 mm ± 0.12); and three additional surface types with different patterns of heterogeneity with combinations of glass pieces: P + S (H1); P + S + N (H2) and P + S + N + C (H3). The plates were placed into the streams and after 105 days the percent cover of macroalgal community was measured. No significant differences among treatments were recorded. However, we observed a trend of macroalgae occurs within the crevices in all treatments and this suggests that, for stream macroalgae, the crevice sizes used in this study was still not enough to provide an expressive algal growth, even in the treatment with bigger crevices.


Considerando que em estudos anteriores a rugosidade da superfície (dimensão micrométrica) mostrou um fraco efeito sobre a colonização de macroalgas lóticas, nós investigamos os efeitos de tamanhos diferentes (em dimensões milimétricas, uma escala ligeiramente maior do que as investigações anteriores) sobre a abundância de macroalgas em três riachos expostos a pleno sol no sul do Brasil. Utilizamos placas lisas de vidro estéreis com formas diferentes: P – superficie plana sem fendas; S - superfície sinuosa (profundidade de fendas com 0.159 mm ± 0.03), N - superfície não-unifome (0.498 mm ± 0.09), C – superficie com estruturas convexas (1.190 mm ± 0.12), e três tipos de superfície adicionais com diferentes padrões de heterogeneidade construídas apartir da combinação de peças de vidro: P + S (H1), P + S + N (H2) e P + S + N + C (H3). As placas foram instaladas nos riachos e após 105 dias a cobertura percentual da comunidade de macroalgas foi medida. Não houve diferenças significativas entre os tratamentos. Porém, observamos uma tendência das macroalgas ocorrerem dentro das fendas em todos os tratamentos e, isso sugere que, para macroalgas lóticas, os tamanhos das fendas utilizadas neste estudo ainda não foram suficientes para proporcionar um expressivo crescimento de algas, mesmo no tratamento com fendas maiores.


Assuntos
Sedimentos Geológicos , Rios , Alga Marinha/fisiologia , Brasil , Ecossistema , Densidade Demográfica , Clima Tropical
17.
Front Psychol ; 5: 870, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25161634

RESUMO

What are the geometric primitives of binocular disparity? The Venetian blind effect and other converging lines of evidence indicate that stereoscopic depth perception derives from disparities of higher-order structure in images of surfaces. Image structure entails spatial variations of intensity, texture, and motion, jointly structured by observed surfaces. The spatial structure of binocular disparity corresponds to the spatial structure of surfaces. Independent spatial coordinates are not necessary for stereoscopic vision. Stereopsis is highly sensitive to structural disparities associated with local surface shape. Disparate positions on retinal anatomy are neither necessary nor sufficient for stereopsis.

18.
Neuroimage ; 89: 23-34, 2014 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-24315841

RESUMO

The survival rates of infants born prematurely have improved as a result of advances in neonatal care, although there remains an increased risk of subsequent disability. Accurate measurement of the shape and appearance of the very preterm brain at term-equivalent age may guide the development of predictive biomarkers of neurological outcome. We demonstrate in 92 preterm infants (born at an average gestational age of 27.0±2.7weeks) scanned at term equivalent age (scanned at 40.4±1.74weeks) that the cortical sulcation ratio varies spatially over the cortical surface at term equivalent age and correlates significantly with gestational age at birth (r=0.49,p<0.0001). In the underlying white matter, fractional anisotropy of local white matter regions correlated significantly with gestational age at birth at term equivalent age (for the genu of the corpus callosum r=0.26,p=0.02 and for the splenium r=0.52,p<0.001) and in addition the fractional anisotropy in these local regions varies according to location. Finally, we demonstrate that connectivity measurements from tractography correlate significantly and specifically with the sulcation ratio of the overlying cortical surface at term equivalent age in a subgroup of 20 infants (r={0.67,0.61,0.86}, p={0.004,0.01,0.00002}) for tract systems emanating from the left and right corticospinal tracts and the corpus callosum respectively). Combined, these results suggest a close relationship between the cortical surface phenotype and underlying white matter structure assessed by diffusion weighted MRI. The spatial surface pattern may allow inference on the connectivity and developmental trajectory of the underlying white matter complementary to diffusion imaging and this result may guide the development of biomarkers of functional outcome.


Assuntos
Córtex Cerebral/anormalidades , Rede Nervosa/anormalidades , Nascimento Prematuro/patologia , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Lactente , Imageamento por Ressonância Magnética , Masculino , Imagem Multimodal , Fibras Nervosas Mielinizadas/patologia , Gravidez
19.
J Anat ; 223(4): 329-36, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23964811

RESUMO

Morpho-functional patterns are important drivers of phenotypic diversity given their importance in a fitness-related context. Although modularity of the mandible and skull has been studied extensively in mammals, few studies have explored shape co-variation between these two structures. Despite being developmentally independent, the skull and mandible form a functionally integrated unit. In the present paper we use 3D surface geometric morphometric methods allowing us to explore the form of both skull and mandible in its 3D complexity using the greater white-toothed shrew as a model. This approach allows an accurate 3D description of zones devoid of anatomical landmarks that are functionally important. Two-block partial least-squares approaches were used to describe the co-variation of form between skull and mandible. Moreover, a 3D biomechanical model was used to explore the functional consequences of the observed patterns of co-variation. Our results show the efficiency of the method in investigations of complex morpho-functional patterns. Indeed, the description of shape co-variation between the skull and the mandible highlighted the location and the intensity of their functional relationships through the jaw adductor muscles linking these two structures. Our results also demonstrated that shape co-variation in form between the skull and mandible has direct functional consequences on the recruitment of muscles during biting.


Assuntos
Crânio/anatomia & histologia , Animais , Fenômenos Biomecânicos , Imageamento Tridimensional , Mandíbula/anatomia & histologia , Mandíbula/fisiologia , Mastigação , Modelos Anatômicos , Modelos Biológicos , Musaranhos/anatomia & histologia
20.
Int J Mol Sci ; 11(12): 5009-26, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21614188

RESUMO

Functional elucidation of uncharacterized protein structures is an important task in bioinformatics. We report our new approach for structure-based function prediction which captures local surface features of ligand binding pockets. Function of proteins, specifically, binding ligands of proteins, can be predicted by finding similar local surface regions of known proteins. To enable partial comparison of binding sites in proteins, a weighted bipartite matching algorithm is used to match pairs of surface patches. The surface patches are encoded with the 3D Zernike descriptors. Unlike the existing methods which compare global characteristics of the protein fold or the global pocket shape, the local surface patch method can find functional similarity between non-homologous proteins and binding pockets for flexible ligand molecules. The proposed method improves prediction results over global pocket shape-based method which was previously developed by our group.


Assuntos
Algoritmos , Modelos Moleculares , Proteínas/química , Sítios de Ligação , Ligantes
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