FORMA
Online ISSN : 2189-1311
Print ISSN : 0911-6036
Volume 30, Issue 1
Displaying 1-10 of 10 articles from this issue
Letter
  • Kazuki Yoshikawa, Takehito Kojima, Akihiro Sugiura, Masaru Miyao
    Article type: research-article
    2015Volume 30Issue 1 Pages 1-4
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    Stabilometry is useful for understanding overall equilibrium function, and is applied as one test of body equilibrium function. It is a simple test in which 60-second recording starts when body sway stabilizes. Objective evaluation is possible by computer analysis of the speed and direction of the sway, enabling diagnosis of a patient's condition. However, conventional stabilometer are very expensive. Attempts have therefore been made to develop a method of stabilometry using a Wii Balance Board. Wii Balance Boards are available at much lower cost than conventional stabilometers. As an application of stabilometry using the Wii Balance Board, we conducted a stabilometry test with subjects viewing 3D images. In this study, we examined the possibility of stabilometry using a Wii Balance Board. We also examined the effect on equilibrium function of stabilometry done with subjects viewing 3D images. We compared conventional stabilometry and the Wii Balance Board. Among the four types of analysis index, a very high correlation was seen in total locus length between the two instruments. Total locus length was the only analysis index for which a strongly correlation was seen with conventional stabilometer. Therefore, it may be possible to use a Wii Balance Board in place of a conventional stabilometer using total locus length. We also performed stabilometry with subjects viewing a 3D image. The results of stabilometry performed with subjects viewing stereoscopic images suggest that the total locus length may be helpful in visually induced motion sickness.

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  • Syed A. Jafar
    Article type: research-article
    2015Volume 30Issue 1 Pages 5-7
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    A case of tiling using a single tile of golden trapezium is presented and each of the five pentagonal sectors when seen in isolation, reveals planes of translation suggesting periodicity. It is shown that this tile not only tessellates Euclidean plane, expanding to infinity, but also maintains perfect regular pentagonal outline at each completed generation of tiling. The entire tiling suggests a five-fold intergrowth structure of a twinned crystal, which should yield sum of five discrete and superimposed ordered periodic diffraction patterns. Clue to this tiling was primarily provided by a Coccolithophore species: Braarudosphaera bigelowii, which makes an elegant regular pentagonal dodecahedron of mineral Calcite, invisible to unaided human eye.

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Art Column
  • Shojiro Nagata
    Article type: research-article
    2015Volume 30Issue 1 Pages 9-18
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    Kolam is a traditional loop pattern, in which a line goes around some dots in an array. In this paper, we reported on our study of the construction of Kolam, describing how many loops a drawn Kolam has. Considering Kolam as a knot-link pattern and a navigating line (N-line) of Kolam as a planar graph of the knot-link, we analyze the loop number as the component number using the Tutte polynomial and the invariant of it. In Appendix A, the author introduced also two matrix processes from the Kolam pattern as a Medial graph to obtain a loop number.

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  • Shojiro Nagata
    Article type: research-article
    2015Volume 30Issue 1 Pages 19-33
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    This art column is introducing Loop patterns applied to traditional and contemporary designs and objects in Japan and Asia. Loop patterns sometimes feature in Knot-Link patterns. The originally eternity, rebirth and dynamics of a loop pattern attracts human mind and then becomes happy-lucky symbol in religious worlds. Recently mysteriousness of loop or knot patterns are understood and are played with the sprit of the patterns by some challengers. The applications of the loop patterns are not only decorations or ornaments for clothing or constructions, but also brain training or stretching tools for education and welfare. At the last, it is mentioned that this loop pattern is very useful topic for understanding and exchanging the world-wide cultures between the different countries.

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Letter
  • Venkatraman Gopalan, Brian K. Vanleeuwen
    Article type: research-article
    2015Volume 30Issue 1 Pages 35-41
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    Pulli kolam is a ubiquitous art form drawn afresh every morning on the threshold of most homes in South India. It involves drawing a line looped around each dot of a collection of dots (pullis) placed on a plane in accordance with three mandatory rules, namely, all dots should be circumscribed, all line orbits should be closed, and two line segments cannot overlap over a finite length. The mathematical foundation for this art form has attracted attention over the years. In this work, we propose a simple 5-step method by which one can systematically draw all possible kolams for any number of dots N arranged in any spatial configuration on a surface. For a given N, there exist a set of parent kolams from which all other possible kolams can be derived. All parent kolams arising from different spatial arrangements of N dots can be classified into parent kolam types; within each type, all parents are topologically equivalent, or homotopic. The number of kolams for agiven N is shown to be infinite if only the three mandatory rules stated above are followed; it becomes finite as more optional rules and restrictions are imposed. This intuitive method can be mastered by anyone to create countless kolams with no prior knowledge or the need for a detailed mathematical understanding. It is also amenable to developing apps and educational games that introduce the concepts of symmetry and topology.

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  • Akihiro Sugiura, Yui Itou, Shino Ota, Miho Shimura, Kunihiko Tanaka, H ...
    Article type: research-article
    2015Volume 30Issue 1 Pages 43-50
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    In this study, we verified the occurrence of visually induced self-motion during a motion movie that included both unpredictable and predictable components by measuring body sway. Eleven subjects watched a static movie for 1 min and 8 sinusoidally moving movies (direction setting: 2, added unpredictable component settings: 4) for 180 s each. The results revealed the following: First, a viewing depth-direction predictable motion movie had high phase synchronization acuity. In contrast, the unpredictable motion component considerably affected the viewing side-direction motion movie. Second, the relationship between the amount of added unpredictable motion components and the synchronization acuity was poor.

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Original Paper
  • Yoshihiro Yamaguchi
    Article type: research-article
    2015Volume 30Issue 1 Pages 51-57
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    Put several rods in the fluid and stir them with the rules of braid. A beautiful and strange stirring pattern appears on the surface of the fluid. We name this pattern "the braid stirring pattern (BSP)". We discuss the topological properties of BSP, for example, the tunnel number, the growth rate of tunnel length, and the ratios among tunnel lengths.

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  • Masashi Miyagawa
    Article type: research-article
    2015Volume 30Issue 1 Pages 59-63
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    This paper examines the angle between the directions of the first and second nearest facilities. An application of the angle can be found in location analysis of refuges where the direction of facilities is important. The angle represents the service level of facility location when customers are serviced by the first and second nearest facilities. The distribution of the angle is derived for regular and random patterns of facilities. The distribution shows how the angle is distributed in a study region, and is useful for location models using the direction of facilities. The distribution of the angle for actual facility location is also calculated.

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  • Shojiro Nagata
    2015Volume 30Issue 1 Pages 65
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    There are errors at the following paper:

    "How Many Loops Kolam Loop Pattern Consists of" by Shojiro Nagata in Forma, Vol. 30, No. 1, pp. 9-18, 2015.

    p. 17, right column, the lines 1, 2, and 3 from the bottom:

    Sentences:

    Note the rank of [mq2] is calculated using arithmetric modulo 2 as an example of ma = [[0,1,1][1,0,1][1,1,0]], mq2 = [[0,1,1][1,0,1][1,1,0]], the rank of mq2 = 2, and then the nullity (=3-2) means 1 loop of ma.

    should be changed to:

    Note the rank of [mq2] is calculated using arithmetic modulo 2 as an example of ma = [(0, 1, 1), (1, 0, 1), (1, 1, 0)], mq2 = [(0, 1, 1), (1, 0, 1), (1, 1, 0)] => (row reduced) [(1, 0, 1), (0, 1, 1), (0, 0, 0)]. The rank of mq2 = 2, and then the nullity (3 - 2 =1) means 1 loop of the medial graph of the planar graph representing the matrix ma.

    p. 18, left column, the matrix mi in the middle:

    should be changed to:

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  • Shojiro Nagata
    2015Volume 30Issue 1 Pages 67
    Published: 2015
    Released on J-STAGE: August 21, 2023
    JOURNAL FREE ACCESS

    There is an error at the following paper:

    "Loop Patterns in Japan and Asia" by Shojiro Nagata in Forma, Vol. 30, No.1, pp. 19-33, 2015.

    p. 30, the caption of Fig. 25:

    The last sentence:

    To trace a moving line-edge in an animation of a large Kolam, for example Kolam called Diamond carpet [5] makes also eye-muscle stretch.

    should be changed to:

    To trace a moving line-edge in an animation of a large Kolam with eyesight, for example the animation video of this Kolam "Kolam-1-15-1-withDiagonalCrossings.wmv" in https://www.youtube.com/user/shonan0 or Kolam called Diamond carpet [5] makes eye-muscle stretch well.

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