Numerical Pathology in Selected Kubelka–Munk Formulas, and Strategies for Mitigation

2021 ◽  
Author(s):  
J. A. Stephen Viggiano
Keyword(s):  
Computational Experiments ◽  
Floating Point ◽  
Input Quantity ◽  
Black Background ◽  
Pathological Conditions ◽  
New Models ◽  
Reflectance Factor ◽  
Transmittance Factor

Causes of numerical pathology in formulas for reflectance factor (R), transmittance factor (T ), and reflectance factor over a perfectly black background (R 0 ) under the Kubelka–Munk model are posited, and alternate formulas believed less prone to these pathologies are introduced. Suggestions are offered not only for R, T , and R 0 , but also for intermediate or adjunct quantities used in the main formulas. Computational experiments were performed to verify that the new models produce the same results as the existing ones under non-pathological conditions, exhibit acceptable levels of precision in a customary floating-point environment, and are more robust with respect to edge cases where an input quantity is zero. The new formulas performed well, with some evidence that the new hyperbolic forms provide better accuracy than their exponential counterparts.

Invariant-Based Anisotropic Constitutive Models of the Healthy and Aneurysmal Abdominal Aortic Wall

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
C. A. Basciano ◽  
C. Kleinstreuer
Keyword(s):  
Arterial Wall ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Aortic Aneurysms ◽  
Fluid Structure Interactions ◽  
Mechanical Responses ◽  
Reinforced Composite ◽  
Pathological Conditions ◽  
Abdominal Aortic ◽  
New Models

The arterial wall is a complex fiber-reinforced composite. Pathological conditions, such as aneurysms, significantly alter the mechanical response of the arterial wall, resulting in a loss of elasticity, enhanced anisotropy, and increased chances of mechanical failure. Invariant-based models of the healthy and aneurysmal abdominal aorta were constructed based on first principles and published experimental data with implementations for several numerical cases, as well as comparisons to current healthy and aneurysmal tissue data. Inherent limitations of a traditional invariant-based methodology are also discussed and compared to the models’ ability to accurately reproduce experimental trends. The models capture the nonlinear and anisotropic mechanical responses of the two arterial sections and make reasonable predictions regarding the effects of alterations in healthy and diseased tissue histology. Additionally, the new models exhibit convex and anisotropic monotonically increasing energy contours (suggesting numerical stability) but have potentially the inherent limitations of a covariant theoretical framework. Although the traditional invariant framework exhibits significant covariance, the invariant terms utilized in the new models exhibited limited covariance and are able to accurately reproduce experimental trends. A streamlined implementation is also possible for future numerical investigations of fluid-structure interactions in abdominal aortic aneurysms.

Morphological and elemental analysis of isolated incubated frog retina-choroid

1984 ◽  
Vol 42 ◽  
pp. 298-299
Author(s):  
B. J. Panessa-Warren ◽  
J. B. Warren ◽  
H. W. Kraner
Keyword(s):  
Elemental Analysis ◽  
Pigment Epithelium ◽  
Human Retina ◽  
Healthy Individuals ◽  
Anterior Portion ◽  
Pathological Conditions ◽  
Frog Retina ◽  
Isolated Retina ◽  
Vertebrate Eye ◽  
Retina Pigment Epithelium

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.

An Ultrastructural Study of the Proliferation Patterns of the Reserve Cells of the Human Cervix Uteri

1972 ◽  
Vol 30 ◽  
pp. 80-81
Author(s):  
Takanori Sohda ◽  
Hiroshi Saito ◽  
Goro Asano ◽  
Katsunari Fukushi ◽  
Katsuya Suzuki ◽  
...  
Keyword(s):  
Ultrastructural Study ◽  
Age Groups ◽  
Point Of View ◽  
University Hospital ◽  
Cervix Uteri ◽  
Morphological Aspect ◽  
Functional Aspect ◽  
Pathological Conditions ◽  
Human Cervix ◽  
Morphological Patterns

Recently, the functional aspect as well as morphological aspect of the reserve cells in the cervix uteri drew much attention in view of the carcinogenesis in squamocolumunar junction. In this communication, the authors elucidate the ultrastructural features of the reserve cells in patients of various age groups visiting our university hospital and affiliated hospital.From conventional light microscopic point of view, the reserve cells tend to be pronounced in various pathological conditions, such as the persisting inflammation, proliferative disorders and irritation of hormones. The morphological patterns of the reserve cells from various stage and degree of irritation were observed.

Surface Ultrastructure of Human Ectocervix in Certain Pathological Conditions

1985 ◽  
Vol 43 ◽  
pp. 570-571
Author(s):  
S. Mukherjee ◽  
T. Guha ◽  
B. Chakrabarti ◽  
P. Chakrabarti
Keyword(s):  
Epithelial Cells ◽  
Marked Reduction ◽  
Squamous Epithelium ◽  
Malignant Tumour ◽  
Surface Ultrastructure ◽  
Normal Tissues ◽  
Pathological Conditions ◽  
Hexagonal Shape ◽  
Columnar Cells ◽  
Scanning Electron

The cervix is an important organ in reproduction. Its malfunction is frequently a factor for infertility. Ectocervix region does not appear to have received much attention although many studies have been reported on the endocervix. We report here our SEM observations on ectocervix in certain pathological conditions compared to normal ectocervix.Ectocervix specimens from human females with specific pathological disorders were processed for Scanning Electron Microscopy by conventional method and they were examined in a Philips SEM.The normal ectocervix is lined by flat layer of squamous epithelial cells with microridges (Fig. 1). These cells are known to be formed from columnar cells through metaplastic transformation. The cells of carcinoma-bearing ectocervix show a disorganised appearance (Fig. 2). In non-malignant tumour surface some cuboidal and few columnar cells were seen (Fig. 3). A cyst appears like an overgrowth on the surface of the squamous epithelium (Fig. 4). In ulcerated ectocervix a marked reduction of epithelial cells are observed (Fig. 5); the cells are devoid of microridges and, the large polygonal cells, as observed in normal tissues, have somehow acquired comparatively small hexagonal shape

Review of New models for mass communication research.

1975 ◽  
Vol 20 (5) ◽  
pp. 431-432
Author(s):  
ANTHONY G. GREENWALD
Keyword(s):  
Mass Communication ◽  
Communication Research ◽  
New Models

Educational Psychology Texts: Two New Models

1969 ◽  
Vol 14 (8) ◽  
pp. 421-423 ◽  
Author(s):  
W. ROBERT DIXON
Keyword(s):  
Educational Psychology ◽  
New Models

Non-Linear Dynamics of Cardiovascular Variability Signals

1994 ◽  
Vol 33 (01) ◽  
pp. 81-84 ◽  
Author(s):  
S. Cerutti ◽  
S. Guzzetti ◽  
R. Parola ◽  
M.G. Signorini
Keyword(s):  
Dimensional Space ◽  
Severe Heart Failure ◽  
Parametric Models ◽  
Deterministic Systems ◽  
Finite Dimensional ◽  
Return Maps ◽  
Pathological Conditions ◽  
Non Linear ◽  
Space State

Abstract:Long-term regulation of beat-to-beat variability involves several different kinds of controls. A linear approach performed by parametric models enhances the short-term regulation of the autonomic nervous system. Some non-linear long-term regulation can be assessed by the chaotic deterministic approach applied to the beat-to-beat variability of the discrete RR-interval series, extracted from the ECG. For chaotic deterministic systems, trajectories of the state vector describe a strange attractor characterized by a fractal of dimension D. Signals are supposed to be generated by a deterministic and finite dimensional but non-linear dynamic system with trajectories in a multi-dimensional space-state. We estimated the fractal dimension through the Grassberger and Procaccia algorithm and Self-Similarity approaches of the 24-h heart-rate variability (HRV) signal in different physiological and pathological conditions such as severe heart failure, or after heart transplantation. State-space representations through Return Maps are also obtained. Differences between physiological and pathological cases have been assessed and generally a decrease in the system complexity is correlated to pathological conditions.

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