Abstract:
A logic circuit that can reconfigure its functions in a nonvolatile manner and a single-electron transistor to be used in the logic circuits are provided. The logic circuit has a single-electron spin transistor that includes: a source; a drain; an island that is provided between the source and the drain, and has tunnel junctions between the island and the source and drain; and a gate that is capacitively coupled to the island. In this logic circuit, at least one of the source, the drain, and the island includes a ferromagnetic material having a variable magnetization direction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an orthosis casting form and, more particularly, relates to such a form comprised of dual density foam and a method of producing the same. 
         [0003]    2. Description of Related Art 
         [0004]    Pronation of the human foot involves an inward rolling motion of the foot as it contacts the ground during a gait cycle. Supination involves an outward rolling of the foot as it contacts the ground during a gait cycle. Pronation and supination of the foot normally occur during the gait cycle and are generally observed as rotation of the heel bone or calcaneus. In particular, during pronation, the heel rotates outwardly and during supination, the heel rotates inwardly. 
         [0005]    Excessive pronation or supination of the foot is undesirable and may cause discomfort and injury. Common maladies resulting from excessive foot motion include heel pain, bunions, hammertoes, neromas, knee pain, shin splints and stress fractures. 
         [0006]    Attempts have been made to provide devices for counteracting excessive pronation and/or supination and for treating symptoms associated with these conditions. 
         [0007]      FIG. 1  shows the calcaneus  10  of a right foot  11  in a neutral position that is aligned properly with the adjacent talus  12  ( FIG. 6 ) and corresponding leg bone  13 .  FIG. 2  illustrates the calcaneus  10  in a pronated position which many times is the result of a weak or fallen arch  14 .  FIG. 3  illustrates a calcaneus  10  in an under-pronated condition which is also known as supination. Directing attention to  FIGS. 2 and 3 , the area in which the arch is located is illustrated by reference number  14 . These illustrations emphasize the importance of proper foot alignment to minimize potential pathologies resulting from abnormal biomechanical forces. 
         [0008]    The most common way of addressing biomechanical problems, such as excessive pronation and supination, is through the use of foot orthosis often referred to as orthotics, which are custom designed forms which fit within a shoe to provide specialized support to the foot of the user. Each orthotic is designed specifically for the foot of an individual. Therefore, an exact impression of the topographical surface of the end user&#39;s foot is critical to the successful manufacture of custom foot orthotics. Those skilled in the art refer to a copy of a user&#39;s foot as a positive while the mating topographical surface is referred to as the negative.  FIG. 4  illustrates a standard orthotic casting form  20  comprised of a crushable foam material  22  such as phenolic foam having a closed-cell structure. The form  20  has a top  21 , a bottom  23  and sides  24 ,  25 ,  26 ,  27  therebetween. The foam  22  of the form  20  deforms when a weight is applied to it. In particular, with respect to the form  20 , a user places his/her foot  11  on the top  21  of the form  20  as illustrated in  FIG. 4 . The user then applies weight to his/her foot  11  and crushes the foam  22  from the top  21  of the form  20 . However, the foam  22  is not resilient and, therefore, maintains its crushed shape such that when the user removes his/her foot  11  from the form  20 , an impression of the topographical surface and outline of the bottom of the foot  11  remains. 
         [0009]    However, unfortunately, when using a standard crushable foam block, a user gets an impression of his/her foot  11  using the crushable foam  22  of the form  20 , and the biomechanical deficiency of the foot manifests itself within the impression given by the foot  11 . That is, in this partial to full weight-bearing state the foot falls into the same position that created the original condition. For that reason, an orthotic fabricated from the impression in the standard form  20  must be further modified by a fabricator to compensate for the biomechanical deficiency. 
         [0010]    An apparatus and a method are needed, whereby the impression of a foot  11  using a crushable foam form  20  accurately represents an impression of the foot  11  in a corrected position. An orthotic, which will eventually be produced utilizing this impression, may then be fabricated without further manipulation of the impression in the form  20 . 
       SUMMARY OF THE INVENTION 
       [0011]    In one embodiment of the subject invention, an orthosis casting form is comprised of a block of crushable foam, wherein the block has a top and a bottom, with sides therebetween. The top has a central region adapted to receive the foot of a user, such that under the weight of the user, the foam is crushed and provides an imprint of the topographical surfaces of the bottom and sides of the user&#39;s foot. The block is made up of at least two different densities of crushable foam. 
         [0012]    A second embodiment of the subject invention is directed to a method of making an orthosis casting form, beginning with a block of single density crushable foam having a top and a bottom with sides therebetween. The top has a central region adapted to receive the foot of a user such that under the weight of the user, the foam is crushed and provides an imprint of the bottom of the user&#39;s foot. The method comprises the steps of removing a portion of the foam from the bottom in the region proximate to the forward portion of the lateral column and replacing at least part of the removed portion with a segment of crushable foam having a greater density, thereby providing greater resistance to penetration of the foam by the forward portion of the lateral column than to the other metatarsals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIGS. 1 ,  2  and  3  are sketches illustrating the rear view of a right foot with a calcaneus in a neutral position in  FIG. 1 , a pronated position in  FIG. 2 , and a supinated position in  FIG. 3 ; 
           [0014]      FIGS. 4 and 5  are sketches illustrating the sequence by which a user produces an impression using a crushable foam form; 
           [0015]      FIG. 6  is a top view of a right foot illustrating the bones of the foot; 
           [0016]      FIG. 7  is a side view of the right foot illustrating the bones of the foot; 
           [0017]      FIG. 8  is a top perspective view of one embodiment of the subject invention; 
           [0018]      FIG. 9  is an end view of the  FIG. 8  embodiment; 
           [0019]      FIG. 10  is a side perspective view of the  FIG. 8  embodiment; 
           [0020]      FIG. 11  is another side perspective view of the  FIG. 8  embodiment; 
           [0021]      FIG. 12  is a side view of the  FIG. 8  embodiment; 
           [0022]      FIG. 13  is a bottom view of the  FIG. 8  embodiment; 
           [0023]      FIG. 14  is a bottom perspective view of the  FIG. 8  embodiment; 
           [0024]      FIG. 15  is another end view but from the opposite end of that illustrated in  FIG. 14 ; 
           [0025]      FIG. 16A  is an end perspective view illustrating a wedge at the rear end of the form in accordance with a second embodiment of the subject invention; 
           [0026]      FIG. 16B  is a perspective view identical to  FIG. 16A  but with the cavity filled with a setting foam; 
           [0027]      FIG. 17  is another perspective view of the form illustrated in  FIG. 16 ; 
           [0028]      FIG. 18  is yet another perspective view of the form illustrated in  FIG. 16 , but including hidden lines to more fully illustrate the wedges; and 
           [0029]      FIG. 19  is yet another perspective view of a form showing a plug instead of a wedge to provide stiffness. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    The Applicants have discovered that by using materials of different density for the fabrication of the form  20 , the manner in which the foot orients itself within the form  20  may be controlled, such that the impression within the form more closely resembles the shape of the finally produced orthotic. 
         [0031]    Throughout this application, reference is made to the parts of a foot with respect to the form  120 . It should be appreciated that the form  120  is sized so that a typical foot, when placed in the central region of the form  120 , will be properly located on the form  120  so that the parts of the foot will contact the appropriate locations on the form  120 . However, the form  120  will be marked to define the front and back so that a user will not place his/her foot in the wrong direction, which would diminish the benefits of the subject invention. 
         [0032]    Directing attention to  FIGS. 6 and 7 , the human foot has a number of bones including the calcaneus  10 , talus  12 , navicular  15 , cuneiforms  16   a ,  16   b ,  16   c , cuboid  18  and the first through fifth metatarsals  125 ,  126 ,  127 ,  128 ,  129 , respectively. The medial column  30  for purposes of this discussion, includes the talus  12 , navicular  15 , the cuneiforms  16   a ,  16   b ,  16   c , and the first, second and third metatarsals  125 ,  126 ,  127 . The lateral column  40  for purposes of this discussion involves the calcaneus  10 , cuboid  18  and the fourth and fifth metatarsals  128 ,  129 . Each of the medial column  30  and the lateral column  40  move in a pivoting motion about the calcaneus  10  such that the forward portion  35  of the medial column and the forward portion  45  of the lateral column  40  (i.e., forward of the calcaneus  10 ) pivot up and down. 
         [0033]    When the forward portion  45  of the lateral column  40  is pivoted upward, the mid-foot locks and the foot  11  becomes relatively rigid so that the individual may walk. The inside column of the foot  11  is referred to as the first ray and comprises the first metatarsal and big toe. The first ray has an independent axis of motion similar to the thumb in a human hand and, therefore, moves up when an application of force is applied from the bottom. The outside of the foot  11  is referred to as the fifth ray and its motion and function mirrors the medial column. In normal gait the outside of the heel strikes the ground first and bears weight quickly followed by the fifth ray and lateral column  40  of the foot  11 . The load across the lateral column  40  forces the joints in this segment to produce an osseous restraining mechanism, often referred to as a “locked position”, so that the forces can be transmitted to adjoining structures. An ideal orthosis mimics the geometry of the foot  11  in this “locked position”. However, using a standard crushable foam form, the foam is significantly crushed before the foot  11  is in the “locked position” such that the negative imprinted in the form  120  does not represent the bio-mechanically correct position of the foot  11 . During this time, the first ray is being pulled down and stabilized by muscles with the net effect of a stable foot structure that minimizes pronation of the foot. In a nonweight-bearing position, if the foot  11  were to dangle, the fifth metatarsal  129  would dangle at an elevation lower than the first metatarsal  125 . As the foot  11  is placed in crushable foam, the fifth ray and lateral column stays lower than the first ray since the single density light foam cannot place sufficient force on the foot to load the lateral column. The resulting impression, or positive, captures the shape of the foot in an incorrect position. Similarly, to reduce pronation or rolling motion of the foot  11  when the user&#39;s foot is in the foam  122 , greater force must be applied to the medial or inside of the heel area. 
         [0034]    Directing attention to  FIGS. 8-15 , the ideal impression within a form  120  would be defined by a cavity or impression  123  having depressions  125   d ,  126   d ,  127   d ,  128   d ,  129   d  ( FIG. 8 ) representing the depressions caused by the metatarsals  125 ,  126 ,  127 ,  128 ,  129  ( FIG. 6 ), wherein each of these metatarsal depressions  125   d ,  126   d ,  127   d ,  128   d ,  129   d  is in the correct elevation relative to one another with the medial surface of the heel higher than the lateral surface of the heel. 
         [0035]    The inventors have realized that a form  120  having dual density foam  122  may be utilized to bias the foot within the form  120  so that the final foot position will produce an impression  123  efficiently suited for fabrication of a matching orthotic with minimum alteration of the impression by the fabricator. 
         [0036]    Such an orthosis casting form  120  includes a generally rectangular block  145  of crushable foam  122 , wherein the block  145  has a top  147  and a bottom  149  with a front side  150 , a rear side  152  and two flanking sides  154 ,  156  between the top  147  and the bottom  149 . The top  147  has a central region  160  adapted to receive the foot  11  ( FIGS. 4 and 5 ) such that under the weight of the user, the foam  122  is crushed and provides an impression  123  of the bottom of the user&#39;s foot  11 . Of particular interest, the block  145  is made up of at least two different densities of crushable foam  122   a ,  122   b.    
         [0037]    It should be understood that the casting form  120  is shown already used with the impression  123  existing. However, one embodiment of the actual invention is directed to the unused form similar in shape to form  20  in  FIG. 4 . 
         [0038]    The central region  160  has a front area  162  proximate to the front side  150  to receive the metatarsals  125 ,  126 ,  127 ,  128 ,  129  ( FIG. 6 ) and the phalanges  135 ,  136 ,  137 ,  138 ,  139  ( FIG. 6 ). The central region  160  also has a rear area  164  proximate to the rear side  152  to receive the calcaneus  10 . Two densities of foam  122   a ,  122   b  are positioned in the front area  162  of the block  145 . Foam  122   a  of lower density is positioned above foam  122   b  of higher density in the region of the forward portion  45  of the lateral column  40  ( FIG. 6 ) of a foot  11 , such that resistance to penetration into the block  145  by the lateral column  40  is greater than resistance to penetration afforded to the medial column  30  ( FIG. 6 ). As illustrated in  FIGS. 8-15 , the higher density foam  122   b  has the shape of a wedge  165 , wherein, as illustrated in  FIG. 9 , the highest part of the wedge  165  is in the region of the lateral column  40  of the foot  11  which would be located proximate to the depressions  128   d  and  129   d . As seen in  FIG. 9 , the wedge  165  tapers downwardly in the direction from the flanking side  156 , adjacent to the location of the lateral column  40  ( FIG. 6 ), to the flanking side  154 . Additionally, as seen in  FIG. 11 , the wedge  165  tapers downwardly from the front side  150  to the rear side  152  to insure that the forward portion  45  of the lateral column  40  of the user&#39;s foot is urged upwardly. 
         [0039]    In general, utilizing this form  120 , with an upward force applied to the forward portion  45  of the lateral column  40 , the foot becomes “locked” and it is more likely that the final impression  123  will have the first metatarsal depression  125 d ( FIG. 8 ) through the fifth metatarsal depression  129   d  approximately level within the impression  123  as indicated by line  132 . While  FIGS. 8-14  illustrate a wedge  165 , an arrangement to produce this upward force or resistance to the forward portion  45  of the lateral column  40  may be implemented in different ways. 
         [0040]    The wedge  165  described herein provides resistance essentially to an entire quadrant of the foot, including the forward portion  45  of the lateral column  40 . To the extent that the forward portion  45  of the lateral column  40  may be accurately located on the form  120 , then it may not be necessary to utilize a wedge  165  but, in the alternative, a different geometry may be utilized to provide a localized downward resistance to the forward portion  45  of the lateral column  40 . 
         [0041]    As illustrated in  FIG. 19 , it should be appreciated that in lieu of a wedge  165  providing resistance to the forward portion  45  of the lateral column  40 , it may be entirely possible to utilize a plug  180  extending upwardly from the bottom  249  of the block  245  in the region beneath the forward portion  45  of the lateral column  40  as identified by the foot outline  182 . Such a plug, while illustrated as cylindrical, may be another geometric shape capable of selectively adding stiffness below the forward portion  45  of the lateral column  40  when a foot is pressed against the form  220 . 
         [0042]    The higher density foam  122   b  may have other shapes including an arch (not shown), wherein the highest part of the shape is in the region of the forward portion  45  of the lateral column  40 . 
         [0043]    What has so far been discussed is an orthosis casting form  120  comprised of a block  145 , wherein the front area  162  has been modified to resist downward motion of the forward portion  45  of the lateral column  40 . 
         [0044]    Briefly returning to  FIGS. 1-3 , as illustrated in  FIG. 1 , the ideal position of the calcaneus  10  is in alignment with the leg bone  13 , or talus bone  12 . A pronated foot, as illustrated in  FIG. 2 , has a calcaneus  10  which is not aligned with the leg bone  13  and causes collapsing of the mid-foot/arch. As a result, the calcaneus  10  is somewhat angled relative to the talus  12 . Just as a dual density foam configuration was located beneath the forward portion  45  of the lateral column  40  to position all of the metatarsals  125 ,  126 ,  127 ,  128   129  along a common level plane, a similar concept may be utilized to urge the calcaneus  10  from an everted position, as illustrated in  FIG. 2 , into the preferred neutral position illustrated in  FIG. 1 . Directing attention to  FIG. 16 , the casting form  120  may further include a higher density crushable foam  122   b  in the rear area  164  to bias the calcaneus  10  in a neutral position as illustrated in  FIG. 1 . 
         [0045]    In particular, as illustrated in  FIGS. 16-18 , higher density foam  122   b  may have the shape of a wedge  170 , wherein the highest part  172  of the wedge  170  is on the side  154  of the block  145  corresponding to the rear area  164  on the flanking side  154  (medial side) of the form  120  to urge the calcaneus  10  to the neutral position.  FIG. 17  is a first perspective view of the form illustrated in  FIG. 16A and 16B , while  FIG. 18  is a second perspective view of the form illustrated in  FIG. 16A . These illustrations show the wedge  170  tapers downwardly, not only in the direction from the flanking side  154  (medial side) to the flanking side  156  (lateral side), but also the wedge  170  tapers downwardly in the direction from the rear side  152  ( FIG. 17 ) to the front side  150 . As illustrated in  FIG. 18 , the wedge  170  affecting the calcaneus  10  may work in conjunction with the wedge  165  affecting the forward portion  45  of the lateral column  40 . 
         [0046]    Whether the cavity  130  is formed with a form  120  having a front wedge  165  or both a front wedge  165  and a rear wedge  170 , as illustrated in  FIG. 16B , the resultant impression  130  may be filled with a setting foam  183  or a similar space occupying material thereby creating a positive copy of the user&#39;s foot in the corrected position. Filling the impression with a setting foam  183  or a similar space occupying material has multiple benefits not only to the customized form described herein, but to standard crushable foam blocks as well. In particular, the individual that takes the foot impression of a patient may not be the same individual that fabricates the orthosis for that patient. More often than not, the “used” foam block with the foot impression of the patient is sent to an individual or company that specializes in fabricating orthosis from the “used” foam blocks. However, the crushable foam is fairly brittle and after a foot impression is made within the block, there may be areas of crushed foam having a thickness of less than 1 inch. Therefore, not only is the crushable foam brittle, but parts of the block are also structurally weak. As a result, when the block, which his usually protected only by a cardboard box, is shipped, the sometimes rigorous shipping experience may cause damage to the block such that the fabricator receives a broken or deformed block. After receiving the “used” block, the fabricator fills the impression with a setting foam to produce a positive upon which the orthosis is formed. If the block is damaged or deformed during handling or shipping, the fabricator must, if possible, reconstruct the block to produce such a positive. 
         [0047]    The Applicants have realized that it is very beneficial to fill the impression with settling foam soon after the impression is made so that not only is the block structurally reinforced for shipping and handling, but just as important, the setting foam captures the shape of the impression before the block may be damaged. This provides a very accurate positive that may be used directly by a fabricator to produce an orthosis, thereby eliminating a step for the fabricator while at the same time providing a positive from the impression as it existed just after it was formed. This technique of filling the impression with a setting foam or a similar space occupying material, as mentioned, may be applied to customized forms as described herein or to standard forms. 
         [0048]    Additionally, a plug (not shown) similar to plug  180  ( FIG. 19 ) may be used in lieu of the rear wedge  170  in the same fashion the plug  180  is used in lieu of the forward wedge  165 . 
         [0049]    The crushable foam  122   a ,  122   b  discussed herein may be a rigid phenolic foam made of a closed-cell structure and having a density between 0.60 and 0.75 pounds per cubic foot (pcf). 
         [0050]    As an example, the foam  122   a  of the form  120  may have a density of 0.6 pcf while the foam  122   b  may have a higher density of approximately 0.75 pcf. 
         [0051]    It should be appreciated that what has been so far discussed is a foam  122   b  of higher density, it is also possible to include in place of the foam of high density  122   b , a non-resilient rigid element that provides selective resistance to the advancement of the foot  11  within the form  120  to bias the lateral column  40  or to bias the calcaneus  10  into their preferred positions. This substitute material for the foam of higher density  122   b  may have the same shapes as previously described herein for the foam of higher density  122   b , but of a smaller proportion relative to the foam  122  since this material will not flex. It is important to note that whatever material may be used in place of the foam of higher density  122   b , it must not be a resilient material because such material after being compressed will rebound, the foam of lower density  122   a  will always be present. As a result, the rebounding material will most likely push out and crack the foam of lower density  122   a.    
         [0052]    The subject invention is also directed to a method of making a foot impression form  120  beginning with a block  145  of single density crushable foam  22   a  having a top  147  and a bottom  149  with sides  50 ,  52 ,  54 ,  56 , therebetween. The top  147  has a central region  160  adapted to receive the foot  11  of a user, such that under the weight of the user, the foam  122  is crushed and provides an imprint of the bottom of the user&#39;s foot  11 . 
         [0053]    Directing attention to  FIG. 11 , the method comprises the steps of removing a portion of the foam  122   a  from the bottom  149  in the region proximate to the area of the forward portion  45  of the lateral column  40 . At least part of the removed portion is replaced with a segment of crushable foam  122   b  having a greater density, thereby providing greater resistance to penetration of the foam  122   b  by the fifth metatarsal  129  than by the other metatarsals  125 ,  126 ,  127 ,  128 . The method may further include the steps of removing a portion of the foam  122   a  from the bottom  149  in the region proximate to the area of the calcaneus  10  and replacing at least a part of the removed portion with a segment  122   b  of crushable foam having a greater density to urge the calcaneus  10  to assume a pronation-neutral position. 
         [0054]    In the event the foam of higher density  122   b  is used to bias the calcaneus  10 , the foam of higher density  122   b  may have the shape of a wedge  170 , wherein the highest part  172  of the wedge  170  is on the side  154  of the form  120  corresponding to the first metatarsal  125  to compensate for over pronation. 
         [0055]    After the impression  123  ( FIG. 9 ) is formed, the cavity formed may be filled with setting foam or a similar space-occupying material to reinforce the form for shipping and ease of fabrication. 
         [0056]    While the apparatus discussed herein involves the use of a foam of lower density  122   a  and a foam of higher density  122   b , it should be fully appreciated that the subject invention is not limited to the selection of foams having only two densities and that two or more foam types may be used alone or in combination to produce the desired results. In one particular example, the higher density foam utilized to bias the forward portion of the lateral column need not have the same density as the foam of higher density utilized to bias the calcaneus into the pronation-neutral position. 
         [0057]    While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. The presently preferred embodiments described herein are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.