527 research outputs found

    Control of Oscillation Patterns in a Symmetric Coupled Biological Oscillator System

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    A chain of three-oscillator system was constructed with living biological oscillators of phasmodial slime mold, Physarum polycehalum and the oscillation patterns were analyzed by the symmetric Hopf bifurcation theory using group theory. Multi-stability of oscillation patterns was observed, even when the coupling strength was fixed. This suggests that the coupling strength is not an effective parameter to obtain a desired oscillation pattern among the multiple patterns. Here we propose a method to control oscillation patterns using resonance to external stimulus and demonstrate pattern switching induced by frequency resonance given to only one of oscillators in the system

    Towards a Theory of Scale-Free Graphs: Definition, Properties, and Implications (Extended Version)

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    Although the ``scale-free'' literature is large and growing, it gives neither a precise definition of scale-free graphs nor rigorous proofs of many of their claimed properties. In fact, it is easily shown that the existing theory has many inherent contradictions and verifiably false claims. In this paper, we propose a new, mathematically precise, and structural definition of the extent to which a graph is scale-free, and prove a series of results that recover many of the claimed properties while suggesting the potential for a rich and interesting theory. With this definition, scale-free (or its opposite, scale-rich) is closely related to other structural graph properties such as various notions of self-similarity (or respectively, self-dissimilarity). Scale-free graphs are also shown to be the likely outcome of random construction processes, consistent with the heuristic definitions implicit in existing random graph approaches. Our approach clarifies much of the confusion surrounding the sensational qualitative claims in the scale-free literature, and offers rigorous and quantitative alternatives.Comment: 44 pages, 16 figures. The primary version is to appear in Internet Mathematics (2005

    Dermoscopic Features of CD8-Positive Solitary Pagetoid Reticulosis on the Left Leg

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    Solitary pagetoid reticulosis, also known as Woringer-Kolopp disease, is a rare subtype of cutaneous T-cell lymphoma. The typical clinical presentation is a solitary, localized psoriasiform or hyperkeratotic plaque or tumor located on the extremities. It primarily affects middle-aged males. Because the clinical features of pagetoid reticulosis are indistinctive, pagetoid reticulosis may progress for years before accurate diagnosis. We reported a 57-year-old Japanese woman who presented with a 1-year history of a solitary erythematous plaque on the left leg. Dermoscopic features simulated Bowen's disease showing dotted and glomerular vessels, whitish scaly areas, and a broad negative network. Dermoscopic features of pagetoid reticulosis have never been reported. We have discussed the diagnostic significance of the observed dermoscopic findings

    Dermoscopy of Pigmented Bowen's Disease Mimicking Early Superficial Spreading Melanoma

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    A 89-year-old Japanese woman presented at our clinic because of a several months’ history of an asymptomatic gradually enlarging pigmented skin lesion on the dorsum of the left foot. Physical examination revealed a single hyperpigmented oval macule of 5 mm with a rough surface. The color of the lesion was dark brown to light brown. Dermoscopic examination demonstrated atypical pigment network with small dotted vessels. Irregular streaks were also partially noted at the periphery. We suspected superficial spreading melanoma and performed an excision. The histologic features were consistent with a diagnosis of pigmented Bowen's disease. We could not completely account for dermoscopic aspects from the pathological findings of hematoxylin and eosin-stained specimens; therefore, specimens were stained with Fontana-Masson stain. It clearly demonstrated the distribution of melanin in the epidermis. We concluded that atypical network was due to an uneven melanin deposition in the variably thickened epidermal rete ridges

    New Azaphilones, Seco-Chaetomugilins A and D, Produced by a Marine-Fish-Derived Chaetomium globosum

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    Seco-chaetomugilins A and D were isolated from a strain of Chaetomium globosum that was originally isolated from the marine fish Mugil cephalus, and their absolute stereostructures were elucidated on the basis of spectroscopic analyses, including 1D and 2D NMR techniques, along with the chemical transformation from known chaetomugilins A and D. Seco-chaetomugilin D exhibited growth inhibitory activity against cultured P388, HL-60, L1210, and KB cells

    Synergistic Activation of RD29A Via Integration of Salinity Stress and Abscisic Acid in Arabidopsis thaliana.

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    Plants perceive information from the surroundings and elicit appropriate molecular responses. How plants dynamically respond to combinations of external inputs is yet to be revealed, despite the detailed current knowledge of intracellular signaling pathways. We measured dynamics of Response-to-Dehydration 29A (RD29A) expression induced by single or combined NaCl and ABA treatments in Arabidopsis thaliana. RD29A expression in response to a combination of NaCl and ABA leads to unique dynamic behavior that cannot be explained by the sum of responses to individual NaCl and ABA. To explore the potential mechanisms responsible for the observed synergistic response, we developed a mathematical model of the DREB2 and AREB pathways based on existing knowledge, where NaCl and ABA act as the cognate inputs, respectively, and examined various system structures with cross-input modulation, where non-cognate input affects expression of the genes involved in adjacent signaling pathways. The results from the analysis of system structures, combined with the insights from microarray expression profiles and model-guided experiments, predicted that synergistic activation of RD29A originates from enhancement of DREB2 activity by ABA. Our analysis of RD29A expression profiles demonstrates that a simple mathematical model can be used to extract information from temporal dynamics induced by combinatorial stimuli and produce experimentally testable hypotheses

    Dermoscopic Features of Eccrine Porocarcinoma Arising from Hidroacanthoma Simplex

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    Eccrine porocarcinoma is a rare cutaneous neoplasm that mainly affects elderly people and grows slowly over a long period of time but often experiences an accelerated growth phase. Eccrine porocarcinoma may arise de novo or evolve from a pre-existing benign eccrine poroma. We reported a 86-year-old Japanese woman presenting with two reddish-colored pendulated lesions on a keratotic light brown plaque on the right thigh. Dermoscopic examination of the light-brown plaque demonstrated many whitish globular structures in a light-brown background. At the two reddish-colored pendulated lesions, polymorphous and prominent vessel proliferation was observed together with irregularly shaped whitish negative network. Immunohistochemical study demonstrated a positive CEA staining at ductal structures and atypical clear cells of reddish nodules. A diagnosis of eccrine porocarcinoma arising in a pigmented hidroacanthoma simplex was eventually established, and the dermoscopic features of eccrine porocarcinoma from hidroacanthoma simplex was described for the first time
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