Reciprocal Force Research Articles

Orthotic compensation for non-functioning hip extensors.

Three point fixation to stabilise joints using a rigid orthosis is relatively simple. When movement is required in a single plane, a hinge can be incorporated preventing superfluous movement and consequent loss of stability and function. Alternatively the Reciprocating Gait Orthosis (RGO) which utilises a system of Bowden cables with a HKAFO to provide reciprocal flexion and extension forces at the hip joint may be used. Free standing is achieved in the RGO by trunk and arm movements, the cable tension effectively "locking" the hips in neutral. Force transfer through the cables also produces reciprocal gait. The upper limbs acting through external supports provide the initiating force, producing truncal extension and subsequent hip extension of the stance leg. The resulting flexion of the swing leg produces a forward step. Currently 40 patients have been fitted with the orthosis in Salford, of whom 22 are Spina Bifida patients (aged 3-34 years). Most have Thoraco-lumbar or upper Lumbar lesions. The device has performed well with 1 episode of "knee clash" and 3 patients have had structural failures. Functional walking has been achieved with the orthosis.

A clinical assessment of the Active Vertical Corrector—A nonsurgical alternative for skeletal open bite treatment

This article describes the Active Vertical Corrector (AVC), which is a simple removable or fixed orthodontic appliance that intrudes the posterior teeth in both the maxilla and mandible by reciprocal forces. By the use of effective posterior intrusion of teeth, the mandible is allowed to rotate in upward and forward directions. The uniqueness of this appliance is that it allows the clinician to correct anterior open bite problems by actually reducing anterior facial height. This treatment approaches the problem at its cause (overeruption of posterior teeth) and provides better facial balance and esthetics than most conventional orthodontic treatment procedures. Problems formerly thought to require orthognathic surgery can now be treated successfully with the AVC.

Skeletal Anchorage Utilising Bone Plates

Abstract Skeletal anchorage may be obtained by bone plates in the ramus, to provide the reciprocal forces required in some orthodontic procedures. Distallising of a lower molar in a crowded buccal segment is described in a Case Report.

Models of Coevolution and Speciation in Plants and Their Pollinators

Coevolution of quantitative characters is modeled for populations of plants and specialized pollinators. Reciprocal selective forces on characters in mutualistic species create lines of equilibria for their mean phenotypes. Diversification between geographically isolated pairs of mutualistic populations can thus occur by random genetic drift. In each species the rate of differentiation between populations depends in part on the effective size of local populations of its mutualistic partner. Sexual selection in a pollinator species, through mating preferences in one sex based on the pollination behavior of the opposite sex, can produce rapid coevolution and speciation in both the pollinator and the plant populations. Patterns of mutualistic coevolution are discussed with particular reference to population structure, ecological interactions, and species diversity in orchids and orchid bees, figs and fig wasps, and yuccas and yucca moths.

On the law of fatigue crack layer propagation in polymers

AbstractA generalized theory of fatigue crack propagation in polymers is presented. The theory accounts for crack propagation through root craze extension accompanied by the dissemination of micro defects around the main crack thereby describing a crack layer (CL) system. In addition to the conventional crack length(l), the CL width(w) is introduced as another kinematic parameter. Applying the principle of minimum thermodynamic forces, evolution of l and w is formulated in terms of reciprocal thermodynamic forces. Accordingly the law of Fatigue Crack Layer Propagation (FCLP) is derived in the following dimensionless form where N is the number of cycles, λ ≈ l(N)/l*; l* being the critical CL length, ω = w(l)/w*; w* being the value of w corresponding to l*, β′ and Q′ are energy dissipation and heat evolution functions, respectively. A version of this law provides good description of growth rates from published data.

SELECTION OF VARIABLES FOR LINEARIZED TRUSS OPTIMIZATION

Three possible variable selections for linearized truss optimization are compared. The available evidence shows that a variable choice of member stresses and member cross-sectional areas is inferior to either of the other two variable combinations, member stresses and reciprocal areas or member forces and cross-sectional areas. The properties of the member force/area variable choice are determined analytically and it is suggested that this selection may well be at least equally as powerful as the member stress/reciprocal area formulation.

ラプラス積分形式による粉体圧縮式の検討

Several filling mechanics act simultaneously at powder compression, although it may be probable that one is dominant at a certain stage of compression or for a particular powder bed. Cooper assumed that there are several types of holes in a powder bed corresponding to these mechanics. A fractional volume change attributed to the filling of the same type of holes is represented as an exponential function of the reciprocal compression force with an inherent constant. Then the overall volume change could be obtained from the sum of them. We generalized the lumped constant form (Eq. (I)) by Cooper to the distributed as shown in Eq. (II).V*=V0-V/V0-V∞=Σni=1ai·exp(-ki/P) (Σni=1ai=1) (I)V*=V0-V/V0-V∞=∫∞0f(k)exp(-k/P)dk (∫∞0f(k)dk=1) (II)Eq. (II) is a Laplace integral which is easy for mathematical treatment. It was shown that several experimental compression equations re-formed to V* could be approximated by the substitution of the Weibull distribution function for f (k).From a standpoint of decrease in unfilled holes, we proposed a generalized Ballhausen's equation (Eq. (III)) parallel to Cooper's. Using several equations, we could obtain h (t) analytically which is defined as the inverse Laplace transformation of V*. It was understood by the examination of h (t) that Kawakita's equation is essentially identical to that of Athy's.V*=1-V*=V-V∞/V0-V∞=∫∞0h(t)exp(-tP)dt (∫∞0h(t)dt=1) (III)After some considerations, it was pointed out that a constant k in Eq. (II) should be comprehended as an apparent stress barrier and a constant t in Eq. (III) as an apparent elastic compliance.

The effect of altered bone metabolism on orthodontic tooth movement

The purpose of this study was to determine how bone remodeling changes induced by nutritional hyperparathyroidism affect tooth movement through alveolar bone. Twelve beagle dogs, approximately 1 year old, were randomly divided into two groups of six. The controls were fed a standard dog diet (calcium 0.54 percent, phosphorus 0.42 percent). The experimental diet was identical to that fed the controls except for a decrease in the calcium (0.12 percent) to phosphorus (1.20 percent) ratio. At the tenth week of diet administration, following extraction of the lower third premolars, the second and fourth premolars were moved toward each other with a reciprocal elastic force of 100 Gm. Twelve weeks later the animals were killed and the mandibles were prepared for laboratory evaluation, which included Paragon 1301 staining of undecalcified sections, scanning electron microscopy, and a bone ash analysis. Radioimmunoassays during the experiment showed that the test animals had significantly elevated levels of parathyroid hormone, indicating a probable state of hyperparathyroidism. The clinical data revealed more rapid tooth movement in the experimental animals. Laboratory data indicated that the hyperparathyroid animals had significantly decreased bone density, as well as bone remodeling changes consistent with high PTH levels. These findings suggest that, in addition to applied force, tooth movement is dependent upon the state of calcium metabolism in alveolar bone.

Direct derivation of the two-shaft system balance conditions for the second order reciprocal inertia forces on the V-type eight cylinders internal combustion engines with a plane crankshaft

By employing the “four shafts balance concept” paper [1] has reported a balance regime for the second order reciprocal inertia forces on the V-type eight cylinder internal combustion engines with a plane crankshaft. Thereafter, paper [2] has acquired a “two-shafts balance” regime, but through a rather tedious roudabout degenerating manipulation. The present article has, but starting out directly from the “two-shafts balance concept”, successfully acquired the same results as those in paper [2]. In addition, we propose, herein, a third balance system which might be, in general, called the slipper balance” regime.

A clinical evaluation of the differential force concept as applied to the edgewise bracket

A study was conducted to retest the hypothesis of “differential force” as stated by Begg and to determine if this concept would apply to the edgewise bracket. Two recognized limitations in this study were that neither the tipping of teeth nor the inherent friction between the edgewise bracket and archwire was measured. An acrylic jig or matrix was constructed to fit over the central incisors. By placing a metal bar in the matrix with a point indented into the metal bar, a reference point for measuring distances to the canine and molars was established. The factor of friction should be mentioned relative to this investigation because in sliding an edgewise bracket over an arch wire, varying degrees of friction impede tooth movement. Friction is relevant in making an absolute comparison between conclusions of the differential force concept found in this study and the differential force concept stated by Begg. The conclusions of this investigation are as follows: (1) When using the Siamese edgewise bracket with continuous arch wires, it does not always follow that with 100 to 150 Gm. of applied force only the canine and not the buccal segment or anchor unit will move. Conversely, it does not always follow that with 400 to 500 Gm. of applied force only the buccal segment or anchor unit will move forward and the canine will not move. (2) Using the sliding mechanics of this study, the percentage of greater rates of tooth movement happening coincident with greater forces was found to be 0.857. (3) When the edgewise bracket and sliding mechanics were used, the curves showed that, in general, reciprocal forces cause reciprocal tooth movement with varying and relative rates of space closure. (4) Subjectively, no relationship was found between pain and increased forces; that is, pain in this study was found just as often on the side with 100 to 150 Gm. of applied force as on the side with 400 to 500 Gm. of applied force. This is not to say that there is not more tissue damage found with the use of heavier forces.

Time-dependent magnetization in a SmCo3.5Cu1.5 single crystal

Magnetization reversal in a SmCo3.5Cu1.5 single crystal has been observed as a functon of the field sweep rate in the range 10−5–104 Oe/sec. The reciprocal coercive force varies linearly with the logarithm sweep rate over a wide range, but lowers abruptly above a certain sweep rate. This seems to suggest that the rate controlling process of magnetization reversal changes from elementary nucleations on the parent domain walls to the domain growth resulting from wall migration.

Prestressed Concrete Design by Linear Programming

The adequacy of a concrete trial section and the determination of the minimum necessary prestressing steel area for a prestressed concrete requires the satisfaction of multiple design criteria. These equations can be linearized through the use of a reciprocal prestressing force factor in the working stress equation and piecewise linearization of the ultimate strength and maximum reinforcement conditions. These data can be postulated in matrix form for input to a standard linear programming optimization computer code, and the optimal prestressing area can be determined. An example shows the application to a routine design.

Time relationship of the P-delta segment in the Wolff-Parkinson-White syndrome

Summary Based on 51 well documented cases of the Wolff-Parkinson-White syndrome (WPW), the authors studied the precise relationship of P and delta from the point of view of chronology and reciprocal electromotive forces. A technique of strong scalar and vectorcardiographic amplification was used combining high gain recordings and photographic magnification reaching standard values up to 40 cm/mV. The time markings 1/1000 or 1/400 sec apart allow a precise reading of the ECG and VCG up to ±2 milliseconds (ms). Greatest attention was paid to discovering the true ending of P and the precise onset of delta. For greater clarity the authors propose a simple grading of the P-delta junction in four types: 1) Considerable overlapping of P ending and delta onset. 2) Moderate overlapping of the latter two. 3) End-to-end of P and delta. The depolarization of P, which is complete, is immediately followed by delta. 4) Postponed onset of delta preserving a free interval between both waves. The extreme time measurements from maximum overlapping to largest partition in our series are −45 to +23 ms. Deformed P loops by precocious delta potentials are described; allusions are made to oversimplifications and sometimes to equivocal wording or labelling used in texts dealing with P-delta segment of the WPW syndrome.

Jung and His Critics

THERE IS STILL A WIDE RANGE OF OPINION ABOUT C. G. JUNG, over six years after his death. In some fields-literary criticism, for example-his name appears with increasing frequency;' in others, such as folklore and anthropology, his name rarely appears at all, or, if it does, it is usually in a disparaging sense. Within his field Jung has his own group of followers, but also a larger group of detractors, most vociferous of whom are the Freudians. They have been consistently hostile to his theories ever since his break with Freud in 19I3 (though they acknowledge that some of his work prior to the break has lasting value).2 It is surprising that, over the years, and especially since Jung's death, the smoke of old disputes has not settled; that his theories have not once and for all been rejected or adopted, or at least clarified; and that he continues to be of interest to scholars in a number of fields, almost as if he were still a living force. In folklore the prevailing opinion of Jung is largely negative. There is occasional talk of archetypes and the unconscious, but mostly Jung's theories are dismissed as sheer mysticism. When Jung's name is mentioned, it is almost as if one were to call up Frazer or Levy-Bruhl in support of an argument-worse, since Jung was neither a folklorist nor an anthropologist. I want to take another look at some of the criticisms of Jung that weighed heavily with folklorists in the past and see if they are still useful guides to his thought today. There are, in fact, relatively few published criticisms of Jung to go on; however, these few damn so strongly any use of his concepts that one almost forgets that they are very brief and touch upon just a small part of his work. Two criticisms, in particular, probably have done more to influence the thinking about Jung in folklore than any of the others, and these will be examined in detail. The first is that of Weston La Barre in his article, Psychology and Folklore, published in the JOURNAL OF AMERICAN FOLKLORE in I948.3 The second is that of Melville J. and Frances S. Herskovits contained in their Dahomean Narrative, published in I958.4 The fact that both of these criticisms are by anthropologists in no way diminishes their force in folklore; on the contrary, it is precisely because of the close relations between anthropology and folklore in areas where Jung's thought might apply that criticism in either field would likely have reciprocal force in the other. Both La Barre and the Herskovitses are critical, in tones of strongest deprecation, of

Biophysical assessment of a reciprocal vertical force system on posterior teeth out of occlusion in a rhesus monkey: By Dale K. Kostiwa, D.D.S., Loyola University School of Dentistry, Chicago, Ill.

Biophysical assessment of a reciprocal vertical force system on posterior teeth out of occlusion in a rhesus monkey: By Dale K. Kostiwa, D.D.S., Loyola University School of Dentistry, Chicago, Ill.

Biophysical assessment of a reciprocal vertical force system on posterior teeth in normal functional occlusion: By Gerald Jeffry, D.D.S., Loyola University School of Dentistry, Chicago, Ill.

Biophysical assessment of a reciprocal vertical force system on posterior teeth in normal functional occlusion: By Gerald Jeffry, D.D.S., Loyola University School of Dentistry, Chicago, Ill.

Hip Lesions of Infants and Children Seen at the Newington Home and Hospital for Crippled Children

In his address at the Hartford Medical Society in June 1909, Arthur T. Legg (43), then Junior Assistant Surgeon of the Children's Hospital in Boston, made the following pertinent remarks regarding the well known affection of the hip which now bears his name: “We are at times painfully aware of the fact that there are many symptoms which we readily recognize in our clinical observations to which we can assign no cause: and it is also an undoubted fact that there are many conditions even which exist today of which we are ignorant, simply from our neglect to observe, or from faulty observation, or again, from faulty deduction even from good observation.” We are convinced of the fundamental importance of the attitude to which Legg gave expression in these words, particularly as it affects roentgen diagnosis. Even a superficial perusal of the literature convinces one of the complexity and breadth of the subject of hip disease. Therefore, much can be learned through accurate observation and deduction. Efficiency in the field of roentgen diagnosis can be attained only through thorough familiarity with all phases of roentgen technic and avoidance of abstract film reading without proper clinical control. Embryological and Anatomical Considerations According to Sir Arthur Keith (37), in the eighth week of intra-uterine existence (20 mm. fetus) the three principal components of the innominate bone meet to form the Y-shaped acetabular suture. In the ninth week, outgrowth of cartilage from the primitive ischium, ilium, and pubis results in the formation of the cotyloid cavity. A synovial lining then appears. In certain cases in the reptilian stage (second month) the acetabular cup fails to develop, and congenital dislocation of the femoral head follows. Similarly, Keith states that cleft palate and imperforate anus may result from arrest of development in this stage. Apparently development of congenital dislocation of the hip has a definite relation to female sexual characters, since the majority of cases (90 per cent) are encountered in female patients. The importance of a knowledge of normal limb bud rotation as an aid to understanding certain hip joint deformities has been recently emphasized by Badgley (1). To simulate the position of the fetal limb buds, the adult should be placed prone with the limbs projecting fin-like at right angles from the trunk; the knees would then face dorsad with the great toes in front (Keith), owing to external rotation. By comparison, the arms would be rotated internally so that the elbows face dorsad. As growth occurs, both limb buds rotate in opposite directions about their long axes. Thus, the elbow ultimately points posteriorly after external rotation and the knee ventrally after internal rotation; the palms thus face ventrad in the anatomical position and the soles dorsad. Finally, as the limb bud rotates from flexion to extension, reciprocal forces come into play at the hip joint.

Reciprocal Electric Force

Reciprocal Electric Force

On induced and other magnetic forces

The question as to identity in the source of those several and mysterious powers of nature by which masses or particles are moved either toward, or from each other, being a question of deep physical interest, the author of this paper has been led to some further investigation of the nature and laws of magnetic force, in the course of which several new facts have presented themselves which he thinks not altogether unworthy of attention. Magnetic attraction as commonly observed being found to depend on certain impressions made on the attracting bodies usually designated by the general term induction, it appears essential to the progress of any inquiry into the laws of those forces operating externally to a magnet through space, to commence with a rigid examination of the nature and mode of action of those inductive forces upon which the reciprocal force of attraction between the bodies immediately depends. These forces of induction may be considered as a series of successive or reverberating influences, operating between the near and opposed surfaces of the magnetic bodies.