Black-eye pattern

Black-eye pattern A more complex structure appears well beyond the primary instability of a hexagonal array through increase in the malonic acid concentration [52]. 

The observed black-eye patterns are not understood. They may arise from a competition among the increasing number of modes that become unstable as the system is driven far beyond the onset of patterns. For example, the second harmonic modes may develop a resonant interaction with the fundamental modes, leading to the black eyes. Alternatively, three-dimensional effects could lead to the black-eye patterns. 

Fig. 3.1 The shapes and patterns of some pleasing designs found in nature or constructed as artifacts (a) the flower of the black-eyed Susan. RmJbetkia hirin, lb) the flower, stem, and leaves of the black-eyed Susan (c) a red eft, Notophtluilrrws vintlescens (d) a cut diamond (c) a paisley tie (f) a snail shell. Cepea ne/noralis (g) a monarch butterfly, Daniws plexippiix (h) a suspension bridge. Which are truly symmetrical ...

Similarly in 2D for patterns of hexagonal symmetry, besides the basic triad of modes ki, k2, ks, one has to take into account the resonant coupling with the first overtone triad Ki = k2 - ks, K2 = k3 - ki, K3 = ki - k2. We will not write down the twelve coupled amplitude equations that result. New possible structures are shown in Figure 9 and presents some similarities with the black eyes structures obtained in the CIMA reaction [47]. Let us also mention that the square patterns may now also be made stable. 

Generally, the phenotype that predisposes an individual to an increased risk of skin cancer is red or blond hair, blue eyes, and fair skin. These characteristics are surrogate measure of the sensitivity of the skin to sun exposure and the tendency to develop nevi, freckles, and sunburns based on the skin type. Freckles, which may appear abruptly after the first high dose of UV radiation sun exposure, represent clones of mutated melanocytes, and their presence is associated with an increased risk of melanoma.12 The Fitzpatrick classification of skin type is used to determine the response pattern of the skin to UV radiation and assess the risk for melanoma. There are six Fitzpatrick skin types Type I skin always burns and never tans, type II skin burns easily and tans rarely, type III skin burns sometimes and tans usually, type IV skin burns rarely and always tans, type V skin always tans and is moderately pigmented (brown), and type VI skin always tans and is darkly pigmented (black). Fitzpatrick I and II skin types are commonly affected by NMSC and MM. The susceptibility to skin cancer, both NMSC and MM, is related to the melanin content of the skin and the skin s response to UV radiation. 

Pupil size can be estimated from direct observation. A variety of cards and scales are available whereby the experimenter compares the size of the pupil to standard patterns and scales. The simplest and most often used card is the Haab pupil gauge. This consists of a card with black circles graduated in size between 2 and 10 mm in 0.5-mm increments. The card is held on the temporal side of the eye out of the subject s vision (to reduce accommodation miosis). Pupil size can be determined to an accuracy of 0.2 mm. A disadvantage of this method is the inability to make measurements in the dark and the possibility that the subject s eyes will react to the test or its administration. 

Figure 4. Sequence of snapshots frame A shows a homogenous phase (note that the black speckles are talcum particles used to trace motion on the gel). Transition to hexagonal patterns is shown in frames B D, followed by the formation of white-eye structures in E. Frames F-H show the subsequent transformation of the white-eye structures to honeycomb patterns. The arrows indicate the direction of particle motion in a single patch of the pattern. Temporal sequence after preparing the system A) 9 min, B) 9.5 min, C)10 min, D) 13 min, E) 17 min, F) 24 min, G) 26 min, H) 30 min.

To create an accurate pattern, a sharp hard black pencil or mechanical pencil assists with fine line definition. Developing the capacity to draw a confident accurate line guided by the eye, known in tailoring as the rock of the eye , is an aspirafional skill for a novice patternmaker. 

A pattern of alopecia is not characteristic but hair loss is most marked on the crown (Hubler 1966). The hairs show an accumulation of air bubbles in the shaft, through which area breakage occurs. This appears to the unaided eye as a black opaque band about 1 mm in length, appearing at the root a few days after thallium intoxication (Hubler 1966). The follicles themselves show, on biopsy, dyskeratosis, necrosis, parakeratosis, spongioform abscess formation, and increased number of telogen follicles. 

Our visual system consists of more than just our eyes. Information from the eyes is transmitted to our brain where the visual stimuli are analyzed and given a meaning. The eye does not see words on this page, but we do. The eye only sees a pattern of black and white dots, which are interpreted by our brain as letters and words that have meanings. Interestingly, we are conscious of the end product (our perceptions of the words, the meanings), and not of the... 

Fig. 74. Clonal origins of the photoreceptor cell layer of the mouse retina. The drawing is a two-dimensional reconstruction from serial sections of the retina of an allophenic mouse with approximately equal numbers of normal (+/+) and retinal degeneration strain (rdird) cells. The development, followed by death, of the rdjrd cells leaves null areas (shown in black) on which clonal mapping is based. A stellate pattern (arrows point to five -f / + components) suggests that the visual cells of each eye are derived from only ten clonal initiator cells that proliferate radially from a small circle. (After Mintz, 1971)...

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