Swimming Pool Design For Resort have a few images linked one another. Bring the newest images of Swimming Pool Design For Resort on this page, and you may pick up the images from this page for personal usage. Swimming Pool Design For Resort pictures are uploaded by our team on July 22, 2018 at 5:29 am. The image collection of Swimming Pool Design For Resort presented here is a few of the most wonderful pictures around the internet and has been seen by 55 viewers.
We pick up several outstanding images which you can manage as design ideas and/or for informational benefit of Swimming Pool Design For Resort. Admin have faith that you are all enjoying our collection of the best picture of Swimming Pool Design For Resort on this blog and use them for personal use. We also provide the pictures in High Definition (HD) Resolution that can be loaded to your laptop. What you need is only click on the compilation of Swimming Pool Design For Resort beneath.


Long before "dirtbag climber" was an archetype, Gwen Moffat exemplified it. As a young woman in the 1940s, the pioneering British climber pieced together work, camped in barns, hitchhiked from crag to crag, bathed in icy lakes, went days without food, deserted the Army and rearranged her life to maximize time spent scaling rock. She went on to become Britain's first female mountain guide, as well as a mother, writer and force to be reckoned with. With a rope around her waist and bare feet, she eschewed the path society told her to take in favor of an enduring and adventurous love affair with the mountains.
In Operation Moffat, young climbers Claire Carter and Jen Randall chronicle Moffat's life, gleaning crucial lessons about sacrifice, passion, love and rock from the 91-year-old legend.


text:
Justia Patents Plug Having Cylindrical Or Annular Contacts Of Substantially The Same Diameter (e.g., Jack-type Plug)US Patent for Electrical connector jack Patent (Patent # 5,522,738)
Electrical connector jack
Sep 18, 1994 - Thomas E. Dorn
An electrical connector jack for a conventional two-conductor electrical connector plug; the plug is inserted into the jack in a given direction to connect a signal source to an amplifier with minimal or no noise when the connection is made. The plug has concentric electrically isolated tip and ring electrodes, with the tip projecting beyond the ring in the direction of insertion. The jack includes two signal contacts (one may be grounded) engageable individually with the tip and ring electrodes of the plug when the plug is fully inserted into the jack; these signal contacts are electrically connected to a signal source such as a guitar pickup. A shorting contact engages and interconnects the tip and ring electrodes until the plug is fully inserted. The signal contacts and the shorting contact may have a common insulator support.
Latest Thomas E. Dorn Patents:
Voltage compensation system
Voltage compensation device
Signal blender for three or more musical instrument pickups
Surge protection for data lines
Electromagnetic pickup for a plural-string musical instrument incorporating a coil around a multi-laminate ferromagnetic core
The conventional tip and ring connector plug utilized in many telephone applications is also used in a number of musical instruments such as guitars, bass guitars, banjos and the like. The plug-and-jack connector is often required to perform a variety of different functions. Thus, in completing a signal connection the conventional plug connector may be required to switch a power source to an amplifier; the power source may have an operating voltage of 9 volts. The connector may also be required to mute other signal connections.
When an ordinary telephone-type connector plug is first plugged into a conventional jack, it almost always touches the sleeve of the jack, which is usually grounded. This produces a rather loud clicking and humming sound which can be very disturbing to listeners. This noise results because the tip electrode of the plug, which is usually the "hot" side of the signal circuit, is connected temporarily to the wrong side of the source of signals to be supplied to the amplifier. In the case of an electrical guitar, the tip electrode may actually be connected temporarily to the body of the guitar and even to the guitar player. The noises produced when a plug-and-jack connection is made have long been a problem and a handicap to guitar players, particularly in instances when the connection is made in the course of a performance. Even in those instances in which the connection is completed before the performance begins, the resultant noise is quite objectionable.
STATEMENT OF THE INVENTION
It is a principal object of the present invention, therefore, to provide a new and improved jack for receiving a connection plug of the tip and ring type, a jack that does not cause the generation of noise at the time a plug-and-jack connection is completed.
Another object of the invention is to provide a new and improved jack for a conventional tip/ring plug connector that is essentially noise free, yet requires little or no increase in the cost of the connector jack.
Accordingly, the invention relates to an electrical connector jack that receives an electrical connector plug inserted into the jack in a given direction to connect an amplifier and speaker to a signal source. The plug includes first and second aligned electrically conductive plug electrodes that are electrically isolated from each other; the first plug electrode projects beyond the second plug electrode when the plug is aligned with the jack in the given direction. The jack of the invention may comprise an insulator support, and first and second electrically conductive signal contacts mounted on the support; these contacts engage the first and second plug electrodes, respectively, in electrically conductive contact when the plug is fully inserted into the jack. The jack further comprises means for electrically connecting the signal contacts to a signal source. An electrically conductive shorting contact is mounted on the support in position to engage and to interconnect the plug electrodes as the plug is initially inserted into the jack; the shorting contact maintains the plug electrodes electrically interconnected until the plug is fully inserted into the jack and the plug electrodes engage the signal contacts.
FIG. 1 is a schematic illustration of an electrical connector jack, for use with a conventional tip/ring plug, constructed in accordance with one embodiment of the present invention, showing the jack and plug when the plug is first inserted into the jack;
FIG. 2 is a schematic sectional view, on a somewhat enlarged scale, taken approximately as indicated by line 2--2 in FIG. 1;
FIG. 3 is an illustration like FIG. 1 but showing the position of the components of the plug and jack when the plug has been fully inserted into the jack;
FIG. 4 is a schematic diagram of a typical circuit in which the plug and jack of FIGS. 1-3 is utilized; and
FIGS. 5, 6 and 7 are sequential views illustrating the movement of the plug into the jack at intermediate stages between FIG. 1 and FIG. 3.
FIG. 1 illustrates an electrical connector jack 10 constructed in accordance with the present invention; jack 10 is employed in conjunction with a plug connector 15 to complete an electrical circuit through a two-conductor cable 11. Plug 15 is mounted on the end of cable 11 and is inserted into jack 10 by moving the plug in the direction indicated by the arrow A.
Plug 15, as shown, is of conventional construction. It includes a first plug member or electrode 12. Plug member 12, sometimes referred to as a ring electrode, terminates at an annular insulator 13 that electrically isolates ring electrode 12 from a second plug electrode, tip electrode 14. In many conventional plugs of the kind illustrated by plug 15, the maximum diameter of tip electrode 14 is the same as the maximum diameter of ring electrode 12. Tip electrode 14 is connected to a conductor (not shown) that extends through ring electrode 12, and each of the tip and ring electrodes of plug 15 is connected to a conductor (not shown) in cable 11. The tip electrode 14 projects beyond ring 12 when plug 15 is aligned with jack 10 in the direction indicated by arrow A. Tip electrode 14 is on the "hot" side of the circuit, in most instances; ring electrode 12 may be grounded when the connection through plug 15 and jack 10 is complete.
Jack 10 includes a support structure, of insulating material comprising a base 18, a front support 17, and a rear support 21. In the construction illustrated in FIG. 1, a conductive guide sleeve 16 having an inner diameter corresponding to the outer diameter of ring electrode 12 is mounted in the front support 17. Sleeve 16 is electrically connected by a conductor 20 to a thin, resilient metal shorting contact member 19 having a plurality of contact fingers 19A. Member 19 may be formed of a thin sheet of tempered spring bronze. The orientation of members 16-19 relative to each other, and relative to the tip electrode 14, is shown in FIG. 2.
Jack 10 further comprises first and second electrically conductive signal contacts 22 and 23 that are mounted on the insulator support member 21 as shown in FIG. 1. Any desired mounting means may be employed. The one signal contact 23 also appears in FIG. 2. Signal contact 22 is connected to one end of a coil 27 that is a part of a signal source 26; the connection comprises a conductor 24. Another conductor 25 connects the other terminal of source 26 to contact 23 of jack 10. In a guitar, this connection is usually grounded. The base 18 of jack 10 may be mounted upon a guitar housing or other stable surface 30 by appropriate means such as a pair of mounting devices 31; see FIGS. 1 and 2.
FIG. 3 shows the plug 15 and jack 10 with the plug fully inserted into the jack, completing the electrical circuit shown schematically in FIG. 4. When the plug-and-jack connection is completed, the end of cable 11 abuts sleeve 16 so that the person using the plug and jack connection (often a guitar player) knows that the connection is complete. Ring electrode 12 of plug 15 is in electrical contact with sleeve 16 of jack 10. The ring electrode is also in electrical contact with the fingers 19A of contact member 19. This connection of electrode 12 to the shorting contact comprising members 16, 19 and 20, however, is immaterial to overall circuit operation. Ring member 12 is engaged with and is electrically connected to signal contact 23 which, of course, is connected to conductor 25 and hence to one end of coil 27 in the signal source, guitar pickup 26. See FIG. 4. Tip electrode 14 of plug 15 is engaged by and is in electrical contact with the other signal contact 22 of jack 10, as shown in FIG. 3. Consequently, tip 14 is electrically connected to conductor 24 and, as indicated in FIG. 4, is connected to the other end of coil 27 in signal source 26. The complete circuit, shown in FIG. 4, provides connection through cable 11 to an amplifier 28 which drives a speaker 29.
The critical stage of operation for connector jack 10, which constitutes the present invention, starts with FIG. 1 and is maintained with continuing movement of plug 15 into jack 10, in the direction of arrow A, until the final connected condition is reached, FIG. 3. Intermediate stages are shown in FIGS. 5, 6 and 7.
When plug 15 first moves into jack 10, as shown in FIG. 1, the tip electrode 14 almost inevitably touches and establishes electrical contact with sleeve 16. But sleeve 16 is not grounded and the connection 20 to contact member 19 is of no consequence electrically. Accordingly, when tip 14 engages sleeve 16 there is no signal supplied to amplifier 28 through cable 11 (see FIG. 4) and there is no noise output from speaker 29.
Continued movement of plug 15 into jack 10 brings the plug to the position shown in FIG. 5, in which the first few fingers 19A of shorting member 19 touch and establish electrical contact with the tip electrode 14 of the plug. At the same time, the ring electrode 12 of plug 15 engages and is in electrical contact with sleeve 16. Consequently, because sleeve 16 is connected to shorting contact 19 by conductor 20, the ring and tip electrodes 12 and 14 of plug 15 are electrically interconnected; they are shorted to each other. The electrical consequence is that the input to amplifier 28 is shorted. There is no noise to be amplified and reproduced by speaker 29, FIG. 4.
The next subsequent stage for the interconnection of plug 15 and jack 10 is shown in FIG. 6, with the plug further advanced into the jack in the direction of arrow A. Physically, conditions have changed, but the electrical condition is the same as in FIG. 5. The only real difference is that the fingers 19A of shorting contact member 19 now electrically engage both the tip 14 and the ring 12 of plug 15 and interconnect the plug electrodes. Sleeve 16 might as well not be there. Thus, at this stage the tip and ring electrodes of plug 15 are still shorted to each other and there is no noise output from amplifier 28 and speaker 29, FIG. 4.
FIG. 7 illustrates the relationship that obtains when plug 15 is nearing final insertion into jack 10. At this juncture, tip electrode 14 of plug 15 has not yet come into contact with the "hot" signal contact 22 of jack 10. The other signal contact 23 of jack 10 has just reached engagement with and electrical contact with ring 12 of the plug. But tip electrode 14 and ring electrode 12 are still shorted to each other through contact member 19 and its fingers 19A. There still is no noise.
From the condition shown in FIG. 7, plug 15 continues its movement into jack 10, reaching the operating condition illustrated in FIG. 3. That is, the shorting contact of jack 10, of which the principal element is shorting member 19, maintains an electrical short or interconnection between the two plug electrodes, ring electrode 12 and tip electrode 14, until plug 15 is fully inserted into jack 10 and the tip and ring electrodes of the plug engage the signal contacts 22 and 23, respectively, of the jack. During the entire operation, due to the presence of the shorting contact comprising elements 16, 19 and 20, there has been no abrupt electrical signal supplied to amplifier 28 (FIG. 4) and no noise output from the speaker 29 driven by that amplifier. Contact 22 engages tip electrode 14 to hold the plug-and-jack connection together.
When a switching operation is carried out by plug 15 and jack 10, as described above and as illustrated in FIGS. 1-3 and 5-7, the tip electrode 14 of plug 15 is exposed to the power voltage, usually 9 volts, employed to actuate amplifier 28. This can be quite damaging to the main power amplifier, and can even destroy the operating cone of speaker 29. This abrupt transition in power levels is effectively avoided by jack 10 with only a minor increase in cost of the jack; in some instances there is no increase at all.
Plugs and jacks of many sizes, shapes, and descriptions are in common use on musical instruments, amplifiers, and speakers, and, indeed, in a wide variety of other communication applications. It will be recognized that the constructions illustrated in FIGS. 1-3 and 5-7 are essentially schematic in nature; they clearly do not represent even a fraction of the various mechanical arrangements that can be utilized to carry out the invention. The overriding feature of the invention is that it consistently provides electrically conductive shorting contact between the tip and ring electrodes of the plug in a plug-and-jack connector throughout the time that the plug is being inserted into the jack and until the final connection to the signal contacts of the jack is completed. The physical arrangement used for the essential shorting connection is subject to substantial variation. Metal sleeve 16 and flexible conductive contact member 19 constitute one arrangement that may be used, mechanically, to carry out the invention. But it will be apparent that a flexible metal sleeve or contact or even a flexible conductive rubber strip can be used to the same end. The shapes and orientation of the elements of jack 10 can be varied to meet requirements imposed by virtually any tip-and-ring plug. The key to the invention is maintenance of the electrical short circuit between the tip and ring electrodes of the plug until the final completion of the operating circuits between the plug electrodes and the jack contacts.
1. An electrical connector jack that receives an electrical connector plug inserted into the jack in a given direction to connect an amplifier and speaker to a signal source, the plug including aligned electrically conductive tip and ring plug electrodes electrically isolated from each other, the tip plug electrode projecting beyond the ring plug electrode when the plug is aligned with the jack in the given direction, the jack comprising:
an insulator support;
first and second electrically conductive signal contacts, mounted on the support, for engaging the tip and ring plug electrodes, respectively, in electrically conductive contact when the plug is fully inserted into the jack;
connector means for electrically connecting the signal contacts to an external signal source; and
an electrically conductive shorting contact mounted on the support in position to engage and interconnect both plug electrodes as the plug is initially inserted into the jack;
the shorting contact maintaining the plug electrodes electrically interconnected until the plug is fully inserted into the jack and the plug electrodes engage the signal contacts.
2. An electrical connector jack for use with a connector plug, according to claim 1, in which one of the signal contacts is a resilient metal member, mounted on the support.
3. An electrical connector jack for use with a connector plug, according to claim 1, in which each signal contact is a resilient metal contact member.
4. An electrical connector jack for use with a connector plug, according to claim 1, in which the shorting contact of the jack includes a plural finger resilient metal shorting contact member which engages both the tip and ring plug electrodes during insertion of the plug into the jack.
5. An electrical connector jack for use with a connector plug, according to claim 4, in which the shorting contact further includes a conductive sleeve engaging and guiding the plug into the jack, in the given direction, and an electrical connection between the conductive sleeve and the shorting contact member.
6. An electrical connector jack for use with a connector plug, according to claim 1, in which the support of the jack is mounted on a musical instrument and the signal source is a musical instrument pickup.
7. An electrical connector jack for use with a connector plug, according to claim 6, in which the musical instrument is a guitar.
8. An electrical connector jack that receives an electrical connector plug inserted into the jack in a given direction to connect an amplifier and speaker to a signal source, the plug including aligned electrically conductive tip and ring electrodes electrically isolated from each other, the tip plug electrode projecting beyond the ring electrode when the plug is aligned with the jack for insertion, the jack comprising:
first and second electrically conductive signal contacts, for engaging the tip and ring electrodes of the plug, respectively, in electrically conductive contact when the plug is fully inserted into the jack;
an electrically conductive shorting contact positioned to engage and interconnect the tip and ring electrodes of the plug as the plug is initially inserted into the jack;
the shorting contact maintaining the tip and ring electrodes of the plug electrically interconnected until the plug is fully inserted into the jack and the plug electrodes engage the signal contacts.
9. An electrical connector jack for use with a connector plug, according to claim 8, in which one of the signal contacts is a flexible resilient, electrically conductive member.
10. An electrical connector jack for use with a connector plug, according to claim 8, in which each signal contact is a flexible, resilient electrically conductive metal contact member.
11. An electrical connector jack for use with a connector plug, according to claim 8, in which the shorting contact of the jack includes a plural finger resilient metal shorting contact member which engages both the tip and ring electrodes of the plug during insertion of the plug into the jack.
12. An electrical connector jack for use with a connector plug, according to claim 11, in which the shorting contact further includes a conductive sleeve engaging and guiding the plug into the jack, in the given direction, and an electrical connection between the conductive sleeve and the shorting contact member.
13. An electrical connector jack for use with a connector plug, according to claim 8, in which the jack is mounted on a musical instrument and the signal source is a musical instrument pickup.
14. An electrical connector jack for use with a connector plug, according to claim 13, in which the musical instrument is a guitar.
1526102 February 1925 Taft
2470915 May 1949 Bosh
4359135 November 16, 1982 Tsuge et al.
5213517 May 25, 1993 Kerek et al.
Filed: Sep 18, 1994
Date of Patent: Jun 4, 1996
Assignee: Thomas E. Dorn (Clarendon Hills, IL)
Inventor: Melvin A. Lace (Prospect Heights, IL)
Primary Examiner: Gary F. Paumen
Assistant Examiner: T. C. Patel
Law Firm: Dorn, McEachran, Jambor & Keating
Current U.S. Class: Plug Having Cylindrical Or Annular Contacts Of Substantially The Same Diameter (e.g., Jack-type Plug) (439/669); Including Arc Suppressing Or Extinguishing Means (439/181)
International Classification: H01R 1718;

redpajama_set_name: RedPajamaCommonCrawl


text:
Q: Apple TV control external HiFi - difference between direct control or Airplay I have my TV connected to my Apple TV 4K over HDMI. I've connected my HiFi over a toslink (optical)connection.
Now there is a difference in controlling the volume if I use an Airplay device or the Apple TV itself.

*

*If I play music from my iPhone via Airplay to the Apple TV, I can control the volume via my phone. That is, the volume of my TV-speakers and the HiFi is changed.

*If I play music directly on my Apple TV and control the volume over the remote, just the volume of my TV is changed. That is, the TV-speakers are controlled, but the HiFi remains at the set volume. So I cannot change the volume of both speakers. (Additionally I see also the volume bar of the TV)
Can I change the behavior of the remote/Apple TV/Audio, so that it behaves the same as the first case?

A: In order to control the volume of your HiFi, you will need to use HDMI-CEC between your AppleTv and your Receiver/HiFi. Data (audio) transmitted over optical is sent at a fixed volume, and relies on the receiver of the signal to control the volume.
If your receiver does not have HDMI with ARC, you may be able to get around this in the following way:

*

*Connect AppleTv to TV via HDMI

*Connect TV Audio Out to your Receiver.

*Configure HDMI-CEC to control the volume on your TV from the AppleTV remote.

*Configure TV Audio Out to be "variable", not "fixed" or "line level". This step will vary wildly depending on your TV.

There will be tradeoffs depending on your TV & Receiver's input/output options.

redpajama_set_name: RedPajamaStackExchange


text:
"Original Root Postulate" on the Midtarsal Joint
Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Jun 6, 2013.
midtarsal joint
< Alcohol consumption associated with risk for Achilles tendinopathy | Partial Tear Issue >
Kevin Kirby MVP
I am starting a new thread based on Dr. Daryl Phillips' comments he made in the Acrylic Materials Used for Orthotics thread. Here is where we started:
Daryl Phillips said:
So the question, Kevin, is this: Is it only about STJ axis theory, or does the pronation moment across the MTJ and MCJs also contribute to the decrease in variation of the CoP?
Remember that pressure against the metatarsal heads can only produce a moment around the STJ axis when there is stability of the joints between the forefoot and the rearfoot.
This brings us back to the original Root postulate that continues to dog everyone, from Schuster to Wernick, to Glaser, and everyone else: Is the foot in its optimal standing state when a person stands with the MTJ at its pronation EROM? And since we can discuss ad-infinatum the definition of the EROM, I will make it this, the EROM that Mert Root could produce with his RA hands.
Simon Spooner said:
Should have known old Mert would rear his head pretty soon with you here, Daryl On an incline, out in my garden, down the beach? In which environment are you hoping to define such an optimal position? And in whom: me with my de-cruciated knee or in my 3 year old nephew? Lets not start getting overly simplistic by pretending that there is one all governing optimal position for all people in all environments, it's just naive. Standing in the position postulated by Root?- which people rarely do unless they are in a podiatrists office or on the parade ground- go to your local mall and observe how people naturally stand on a hard, flat surface- bet it's not how they stand in front of you in your office. Are those people in the mall all barefoot or are they wearing shoes of varying construction? Moreover, lets not divert this interesting thread.
Daryl said:
This is not a defense of Mert -- I just didn't want to get bogged down into the definition of the EROM of the MTJ, so I used him because he couldn't produce very much pronatory moment around the MTJ axes. However the stiffness needs of an orthotic do go back to the Root Postulate. (I call it the Root Postulate because I can find no one in the literature that makes such a statement -- everything else Mert may have said, I can find an earlier reference for). If you tell me that you are still taking NWB casts, then I will say that you are still a believer in that postulate. If you are now doing partial WB casts, then I will say that you have discarded the postulate. And if you discard the postulate, then you have to have a new postulate to tell us how a vertical force against the metatarsal heads can produce a moment around the STJ. Now the Root postulate is expanded by the Sarrafian twisted plate paradigm, which Clint Jones seems to have even some additional insight with his wring theory.
So put aside Mert . The question had nothing to do with him. What I asked is whether the MTJ or other lesser tarsal joints also contributed to the improved stability? Yes I will always agree that the lack of variation in the CoP has to have equilibrium around the STJ axis, however the Root Postulate is what allows that equilibrium to occur. I should probably start another thread about midfoot stability as I've deviated too far from the original subject.
Hopefully I'll have more real data for you in the near future about orthotic stiffness of acrylic vs. polypro.
Kevin Kirby said:
Daryl:
Regardless of what Mert Root believed and also what he did and did not say, here is what I believe.
Ground reaction force (GRF) acting on the plantar metatarsal heads will cause multiple mechanical effects across multiple joint axes at the instant of GRF application. For example, GRF acting plantar to the 4th and 5th metatarsal heads will nearly simultaneously cause an increase in dorsiflexion moment at the 4th and 5th metatarsal-cuboid joint, a dorsiflexion moment at the calcaneo-cuboid joint, a pronation moment at the subtalar joint (STJ) axis (assuming the GRF vector's line of action is lateral to the STJ axis) and an ankle joint dorsiflexion moment. Since a force cannot exist against a body without a reaction force, then we must assume that if the ground can apply a reaction force against the metatarsal head, then all these moments at the more proximal joints occur nearly simultaneously since the masses and moments of inertia of these foot bones are negligible relative to the large magnitudes of GRF acting on the plantar foot.
By the way, Daryl, the midtarsal joint should not be described as having as having a pronation-supination axis since it is not either a uniaxial or biaxial joint, contrary to what Mert Root lectured on and wrote in his books for a few decades.
You will need to start a new thread here Daryl since you are starting to get Simon and myself very interested in these discussions....by the way, Simon has been in hibernation recently here on Podiatry Arena and I want you to know that it took someone like you to get him out of his long springtime snooze....
Bruce Williams said:
I respect your response but the same can be said of Kevin's across the board descriptor of the STJ axis. In whose foot, with what amount of AJ rom, with or without anterior FF equinus, etc.
I understand what Daryl is saying and it is a valid argument and has not been sufficiently addressed or studied for that matter.
Ultimately medially posting the heel or arch will only work appropriately once the lateral column stops dorsiflexing. Also the medial column will not achieve optimal DFion stiffness, IMHO, in this same instance.
The midfoot / forefoot response is every bit if not more important to rotatiional moments about the STJ than how or where the heel is posted.
They both have affects that come into play in a specific timely matter. If that timing is off, then compensations, detrimental or not, will occur.
I understand what Daryl is saying, I just think it's for another thread. This is a good thread on material properties- lets keep it that way. When Grace was a baby she had a toy train with the carriages connected by string- i could pick up the lead carriage without the other cars being picked up until enough tension was generated in the string connecting it to the next carriage. Like I said, lets talk about it, but in a new thread. I've argued this analogy before with Kevin and others.
Kevin, regarding my spring hiatus: I was sick and tired of certain individuals ruining every thread. It's great to have some new people here who I know that I can debate with, disagree with, learn from and yet still remain courteous to and be good friends with when we come together at conference. Moreover, my sister underwent a kidney transplant 6 weeks ago and Grace is ripping up the South West (SW) regional BMX series (currently ranked 1st SW and 5th Nationally), so I've had my mind on other things.
Kevin A. Kirby, DPM
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Website: www.KirbyPodiatry.com
FaceBook: www.facebook.com/kevinakirbydpm/
Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
Kevin Kirby, Jun 6, 2013
Re: Daryl Phillips' "Original Root Postulate" on the Midtarsal Joint
The bottom line here is that, once the forefoot is loaded by ground reaction force (GRF), any increase or decrease in GRF in the metatarsal region of the plantar foot will be instantly transmitted to the STJ and ankle joint, due to the compression and tension forces with the joints making the foot more like a beam (ala John Hicks) than like a more compliant "bag of bones" seen when the foot is non-weightbearing.
Mert Root was wrong in many things, and this is yet another one of them. There is no fixed axis for the "longitudinal midtarsal joint", there is no fixed axis for the "oblique midtarsal joint", there are not two simultaneously occurring midtarsal joint axes when considering the movements of the naviculo-cuboid unit relative to the rearfoot unit and there is not just pronation and supination possible at the midtarsal joint (since the joint axes of the MTJ are infinite and highly variable, not at all liked fixed hinges) and there is definitely no "locking" of the midtarsal joint.
To call these ideas a "Root Postulate" is giving way too much credit to the man for something, I believe, he described erroneously and inadequately. Mert Root was very good at describing many things in podiatric biomechanics, midtarsal joint biomechanics was not one of them, in my opinion.
Kevin Kirby said: ↑
Mert Root was very good at describing many things in podiatric biomechanics, midtarsal joint biomechanics was not one of them, in my opinion.
I tend to agree. One of the most interesting studies on the midfoot which tests the "Rootian postulate" is this one: http://www.amputation.research.va.gov/limb_loss_prevention/Midtarsal_Joint_Locking.asp
Amongst their statements they say:
"Unexpectedly, we found a nonsignificant trend of increased range of motion of the navicular in the frontal plane from forefoot dorsiflexion to plantar flexion when the hindfoot was inverted compared to everted (p = 0.06). The cuboid data for the same loading conditions also increased when the hindfoot was inverted, but the difference was not significant (p = 0.3)."
"No significant difference in the frontal plane range of motion from forefoot eversion to inversion of either the navicular or cuboid while the hindfoot was everted or inverted was detected (p = 0.2 and 0.8, respectively)."
Although the sample employed was relatively small, this study does appear to provide objective data which disproves the hypothesis presented by Merton Root. You may see a decrease in forefoot to rearfoot stiffness when the rearfoot is everted, but it isn't likely to be happening at the talonavicular joint, nor the calcaneocuboid joint as described by Root.
Simon Spooner, Jun 6, 2013
timharmey Active Member
This is intresting !I have often questioned the idea that the mid-tarsal locks, it is often thrown in to papers as if it is a stone-walled fact, to hear it questioned is refreshing
timharmey, Jun 7, 2013
Regarding "end range of motion" (EROM) at the midtarsal joint (MTJ), I believe this term EROM is poor terminology to describe MTJ biomechanics.
Would we describe a leaf spring, when it is loaded to 1/30th of its maximum capacity as being at the "end of its range of motion"? No.
Would we describe a leaf spring, when it is loaded to 1/30th of its maximum capacity as being "locked"? Of course not.
Mert Root could probably load a MTJ with 10 pounds of force and this was called "the locked position of the MTJ". However, the same forefoot, during running, was likely bearing 300 pounds of force in a 150 pound individual. Is this terminology, "EROM" or "locked" the proper terminology to describe the equilibrium position of a spring-like structure under load such as is present within the viscoelastic longitudinal arches of the feet? Not in my opinion.
What then to call this position of the MTJ where when we manually dorsiflex the metatarsal heads and the forefoot seems to stop dorsiflexing on the rearfoot?
Locked? No.
End range of motion? No.
Loaded equilibrium position? Yes.
I like this terminology that the MTJ is loaded and in equilibrium to describe the condition where the forefoot is dorsiflexed and stops moving under a given load much better since:
1. It does not imply that the end range of motion of the MTJ has been reached.
2. It does not imply that the MTJ has "locked" in one loaded position and doesn't move past that locked position.
3. It allows for an infinite number of equilibrium positions which are dependent on the load being placed on the forefoot, which is the way the foot actually works.
I like this terminology that the MTJ is loaded and in equilibrium to describe the condition where the forefoot is dorsiflexed and stops moving under a given load much better
Splitting hairs: the MTJ could be loaded and moving at a constant velocity and still be in "loaded equilibrium". The position in this case being time dependent.
Kevin, reading your post made me realize that my own definition of end of range of motion was very very similar to your loaded equilibrium position. There definitely needs to be a term for the position of a joint where ligaments are providing resistance (I had typed limiting here, but that is also a loose definition) to further motion. It could be defined as the point in range of motion in a certain direction where the stiffness changes. For example, as the cuboid dorsiflexes relative to the calcaneus, when starting from a plantarflexed position, there will be very low stiffness. At the point at which tension in the plantar ligaments develop tension there will be an increase in stiffness of the joint. Of course, this position of the joint may be slightly different from the loaded equilibrium position at a standing load. A good research question is whether that difference is significant in terms of doing research on the joint. How much stretch is there in the ligament?
There should also be a direction associated with the term loaded equilbrium position. Taking the CC joint again, with a dorsiflexion moment on the forefoot, the plantar ligaments will be tight, but the medial and lateral ones might not be. There are still some difficulties with the precision of the terminology.
efuller, Jun 7, 2013
So is it a rigid beam with "instant transmission" of force from the metatarsal region across the subtalar joint axis, or is it a variable stiffness "leaf-spring"? The two concepts/ models seem at odds with one another unless the spring stiffness is very high. Although the force at one end of the spring will be the same at the other end.
Good point, loaded static equilibrium would work. As Eric stated, the terminology is difficult.
efuller said: ↑
As I mentioned in my reply to Simon, "loaded static equilibrium" takes care of the rotational velocity question, but I'm not sure it needs be added since it would be understood. Adding the direction, such as "dorsiflexion loading static equilibrium position" would further add to the precision of the term and is something I considered when I first wrote my post on this subject this morning.
Probably "dorsiflexion loaded equilibrium position of forefoot" would be sufficient since the term "static" would be understood.
It could be modeled effectively as a leaf spring with instantaneous transmission of force through the foot. It could also be effectively modeled as a compliant beam with instantaneous transmission of force through the foot. A more complex, but more accurate, model would integrate the known elastic moduli of the bones and ligaments, their geometry and their viscoelastic properties to calculate their time-dependent mechanical behavior such as could be done with dynamic finite element analysis.
In any instance, the point I am trying to make is that we need to stop using the terms "locked" and "end range of motion" to describe a mechanical system (i.e. the longitudinal arch of the foot) that is spring-like in nature. In other words, the longitudinal arch of the foot will deform more with increasing load, it is not "locked" and is not at the "end range of motion" at lower magnitudes of loading forces.
Good discussion.:drinks
Lab Guy Well-Known Member
Kevin, I really like "Loaded equilibrium position", as it applies to closed kinetic chain.
Would it be accurate to say the following:
Loaded equilibrium position would be between the proportional limit and the yield point of the elastic range of the stress-strain curve.
Overloaded equilibrium position would be within the plastic range of the curve.
Lab Guy, Jun 7, 2013
This makes me think of a test that John Weed described. When standing, you try and run your fingers under the medial and lateral sides of the foot in attempt to assess range of motion and/or load on that side of the foot. There are feet that will have much more load medially than laterally. There is some load laterally, but very little. Is this the dorsiflexion equilibrium position? When I see these feet I assess the maximum eversion height and will make an orthotic that attempts to achieve that "position". What I believe that I'm trying to do with this equalize the load of both sides of the foot. I cast non weight bearing in an attempt to get the position of the foot where the lateral plantar ligaments are taut. Where the ligaments become taut may be the position where the most people understand as the position at the end of range of motion. They also have the term subluxed where the joint is forced beyond the "end of range of motion." If a majority of people understand, like me , that the definition of end of range of motion is where the ligaments become taut, then could we still use the term end of range of motion?
If a majority of people understand, like me , that the definition of end of range of motion is where the ligaments become taut, then could we still use the term end of range of motion?
Eric, perhaps using the term, functional end range of motion (FEROM). For example, I have hallux limitus and have my FEROM on dorsiflexion is about 15 degrees. Functionally, my joint will dorsiflex from 0 degrees to 15 degrees without problems. Beyond 15 degrees, there will be pain with each additional degree.
I am still partial to "loaded equilibrium position". The tautness of the ligaments are bringing the angular velocity of the joint to a stand still. When ligaments stretch further, subluxation followed by dislocation will occur.
Jeff Root Well-Known Member
I believe that Merton Root theorized that the midtarsal joint would be maximally pronated during resting stance in the "normal" foot. If you read his descriptions of joint compensation for osseous conditions, I think you will find that he described several situations in which the MTJ would not be fully pronated in relaxed stance. For example, when he described how the foot compensates for a plantarflexed 1st ray, he said that grf acting on the 1st met would first cause dorsiflexion of the 1st ray. If the range of dorsiflexion of the 1st ray was not sufficient to compensate the plantarflexed 1st ray (and everted ff), then the midtarsal joint would need to supinate to compensate the remaining amount of the plantarflexed 1st ray condition. In this case, the mtj would be supinated during relaxed stance.
Root also was referring to the normal anatomical rom of the mtj and other joints when he described end range of motion. He described subluxation as that motion which occurs when joints are moved beyond their normal anatomical rom. If the mtj has no end rom, then I suppose the ankle joint also has no end rom until you apply enough dorsiflexion force to drive the dorsum of the foot into the anterior aspect of the tibia.
Jeff Root, Jun 9, 2013
I will also add that Merton Root described things better than those before him did and it is up to you all (Kevin, Simon, et al) to describe things better than those before you did! Root was extremely successful in getting standard terminology adopted into a profession that was sorely lacking it. While many of the terms that have evolved on the podiatry area might be better or more scientifically correct, they have not become commonly accepted as modern American Podiatric nomenclature. You have much work to do to equal Roots success. I wish you luck!
Jeff Root said: ↑
If the mtj has no end rom, then I suppose the ankle joint also has no end rom until you apply enough dorsiflexion force to drive the dorsum of the foot into the anterior aspect of the tibia.
The observed "range of motion" for a joint will be dependent upon the load applied. If we consider the range of motion as the phenotype then this will be due to an interaction between genotype and environment and will be highly variable between individuals:
http://www.jcdr.net/article_fulltex...h=May&volume=7&issue=5&page=790 - 793&id=2959
There was an article in Podiatry Now this month discussing PhD's at the University of Salford: "Salford PhD student success helps build podiatry science base" (Podiatry Now June 2013 p.7). One of the successful PhD candidates, Hannah Jarvis for her PhD examined the Root biomechanical model of foot function. I quote from the article:
"Taking data from 100 healthy individuals she has been able to test the relationship between static measures of the foot (such as rearfoot varus, and subtalar neutral), and the dynamic behaviour of the foot. She has also investigated the extent to which Mert Root's description of foot motion matches data from multisegment kinematic foot models. On both counts the Root model does not stand up to the data and her work looks set to forge a change in how we approach foot assessment and define the normal foot"
"Chris [Prof. Chris Nester] said 'for me, Hannah's work will put to bed the debate about the Root model: its time to move to a data-led model of foot function using the plethora of data within the literature and Hannah's experiments'".
If the decline in interest in podiatric biomechanics is to be halted in America, I should sincerely hope that educators within the USA are taking note of what has been happening in the rest of the world for the last 20+ years. I look forward to reading Hannah's PhD thesis.
examined the Root biomechanical model of foot function. I quote from the article:
......"Chris [Prof. Chris Nester] said 'for me, Hannah's work will put to bed the debate about the Root model: its time to move to a data-led model of foot function using the plethora of data within the literature and Hannah's experiments'".
I have not read the article, but was it really the "Root Model" or was it the interpretation of what a lot of people use in clinical practice (in the UK) and call the "Root Model", but bears no resemblance to what Mert Root actually said and what really is the "Root Model". Making a foot orthotic with a rearfoot post made on a cast of the foot with the STJ in neutral is hardly 'Root Theory'. ..... I have no problems if it was a critique of a foot orthotic with a rearfoot post made on a cast of the foot with the STJ in neutral.
Almost all of the critiques I have seen of "Root Theory" in recent times were all Straw Man critiques ... in that they critiqued what the perceived as 'Root Theory', but when you look at what it was they were critiquing was not really 'Root Theory' at all, but there flawed perception of what they thought it was (and I have been guilty of that in the past)
For eg since when has the reliability of measurements used in clinical practice have to do with proving 'Root theory' wrong - its just showed that the measurements that were used in clinical practice are not reliable! I recently recall seeing someone used Bellchambers work on moments driving tibial motion pointed to a flaw in Root Theory .... I still have not figured out what it had to do with Root Theory!
(I really enjoyed listening to Daryl Philips in Meet the Masters last week - it was a good historical reminder of what Root Theory really was)
Craig Payne, Jun 9, 2013
Admin2 Administrator Staff Member
Other threads tagged with: midtarsal joint
Mid-tarsal Joint biomechanics?
Osseous locking mechanism
lock and load
Midtarsal Joint Equilibrium Theory
Midtarsal joint locking
Midtarsal Joint Kinematics: Motion vs. Stiffness
Midfoot position, ROM and stiffness
The "Midtarsal Joint"...
Admin2, Jun 9, 2013
Rob Kidd Well-Known Member
Well of course, exactly this happens in the formation of squatting facets in those ethnic groups that do that - squat. Mainly Asia, but also South Africa. Yes, they do extend their EROM to such a point that the tibia and talus make contact, and leave facets in the contact area. This runs into the areas of genetic assimilation - AKA epigenetics, but that is a different story, Rob
Honorary Research Associate, Institute for Human Evolution, University of Witwatersrand
Fellow of The Centre For Human Biology, The University of Western Australia
"Please God, deliver me whole from my condemnation of those who criticise evolution......."
http://www.youtube.com/watch?v=mjF_v_9nXXM[/URL]
Rob Kidd, Jun 9, 2013
Craig Payne said: ↑
I agree with your points, Craig. I'll reserve judgement until I have read the thesis.
With the exception of the ankle joint, Merton Root said you only need ounces of force to move a relaxed joint to its end rom during clinical examination. As a simple example, dorsiflex your fingers one at a time to their end rom with your opposite hand. Once you reach the effective "the end rom" using ounces of force, continue to apply a dorsiflexion force. You will immediately begin to feel a pain sensation as you attempt to move your fingers beyond their normal dorsiflexion end rom. Your pain receptors are trying to tell you something. If you continually did this you would probably increase the dorsiflexion end rom and increase the total rom of your fingers. So the normal rom of a joint is dependent on how that joint is used by the individual at a given point in time. Isn't that why we recommend stretching exercises to increase the ankle joint rom in individuals with a tight heel cord?
As I mentioned the one joint Root recommend evaluating differently was the ankle joint. He believed that due to the size and strength of the achilles tendon, he not only used significantly more force to examine the range of dorsiflexion of the ankle joint, he also had the patient actively dorsiflex their ankle joint during the examination.
We know from fluoroscopic studies that elite high jumpers get mtj subluxation/deformation in the talonavicular joint of their plant foot just before takeoff. But Root was not looking at such activities. He was using average individuals (not elite athletes, etc.) who mostly did average tasks such as walking. His work was prior to the running craze of the early 1970's, so things were much different at that time. If you disagree with his methods of evaluating joint rom, fine. Come up with a better technique and publish a book with those techniques like Root did so the methods can be adopted or at least scrutinized by a larger community of experts.
I see biomechanical examination of the foot as dying art here in the U.S. So in my view, efforts to "improve" on Root theory are failing miserably at this time in this county. Some individuals have used criticism of Root theory as justification to abandon biomechanical examination. This seems very unfortunate to me.
Come up with a better technique and publish a book with those techniques like Root did so the methods can be adopted or at least scrutinized by a larger community of experts.
There doesn't need to be a book, as this should only provide a secondary source of information. One needs to look at original work published in peer reviewed journals. When it comes to ankle joint dorsiflexion, I quite liked this one: http://steinhardt.nyu.edu/scmsAdmin/uploads/006/435/41-04 Wilken 2.pdf
That biomechanical examination of the foot is a dying art in the USA could be due to many factors: lack of improved clinical efficacy associated with existing techniques might be one; greater earning potential from performing surgery might be another. My dollars are on the another. As an outsider, who pops over to the states to look in every now and again, the health-care system in the States is so financially driven that it's unbelievable. I guess that's capitalism at it's extremes. Is it good to live in a full on capitalist society... I'll let my colleagues who are living the "American dream" answer that one... Here's multi-millionaire Jessie J telling us her thoughts...
http://www.youtube.com/watch?v=qMxX-QOV9tI
"I don't think so, I think that's a lot of bull"- P.M. Dawn
All I know is that the last time I was in the States, the workshops on "billing and coding" were better attended than the workshops which might have enabled practitioners to improve their patients care. To me, that said everything.
How clinically practical is this? Not a all! Root would check the range of dorsiflexion of the ankle with the stj in the neutral position. If the patient had ten or more degrees of dorsiflexion he believed that would be adequate for normal locomotion. If the patient had less than ten degrees, he would quickly pronate the stj and check the range with the stj maximally pronated to see if the effective rom could be increased by pronatory compensation at the stj. It only takes a few seconds. Biomechanics must be practical.
One reason that biomechanical examination is dying in not necessarily because of surgery, but because many practitioners make orthoses for patients without conducting a biomechanical examination. They can get paid just as much and they cut out most of the labor. This is probably why there so many orthotic treatment failures.
I'll let my colleagues who are living the "American dream" answer that one... Here's multi-millionaire Jessie J telling us her thoughts...
Be careful who you listen to. Starting at the 54 second mark this poor girl demonstrates that she doesn't even know her right from her left. LMAO! I stopped watching right after that!
You lasted longer than me, Jeff. Not my cuppa. To quote an old favourite: "I wouldn't trust her to sit the right way around on a toilet seat". Ironic that we have a multi-millionaire media tart telling us that "it's not about the money" - capitalism sucks and it will ultimately be the nail in the coffin of podiatric biomechanics in the States. For all it's faults, the NHS draws us back from this here in the UK. Perhaps this is why we appear to be more inclined to read the research and go with the evidence?
The problem is, and with the greatest respect, your dad just made up the ten degrees thing... his technique of assessment had many degrees of error in terms of it's reliability/ repeatability not least because the loading force could not be standardised (as it could in the study I cited), he couldn't possibly have known the "ten degrees" was "normal" in the population of patients he was seeing, let alone any other population. Too many variables to link to an unproven ideal / "normal" call it what you will. Moreover, he clearly assumed that no-one wore shoes with a heel height differential.
The reality is that actually here in the UK we were pretty advanced with putting the "mechanics" in the biomechanics before your dad came along, Jeff. In my humble opinion, your fathers work as well as doing some good in terms of standardising terminology, actually had a negative impact on podiatric biomechanics here in the UK. The likes of Gordon K. Rose and William Sayle-Creer were pretty much heading in the right direction before your father's work was even published. The subsequent adoption,bastardisation, and promotion of your fathers work in the UK by Langer probably did more harm than good for twenty odd years. Not your father's fault- he didn't ask Langer to bastardise it, nor promote it, but there you go. Just my opinion. I'm sorry if that sounds harsh. I truly mean you no offence in respect to your late father (I have a late father too, and understand your desire to defend), I'm merely someone who has been involved with podiatry for twenty five years, have a research degree, have specialised in podiatric biomechanics and have reviewed and lectured upon the history of podiatric biomechanics both here in the UK and abroad.
Sayle-Creer is interesting here, since he was advocating differentially loading the lateral forefoot and medial rearfoot using contra-lateral forefoot and rearfoot wedging in foot orthoses to relieve the stress on specific tissues in 1938. I believe you father was 16 years of age at this point. And G.K. Rose was talking about changing the axial position of the subtalar joint by means of foot orthoses in 1958.
And lastly, forgive me if I am wrong, but aren't you a fireman by training, Jeff? How many of your fathers consultations did you actually sit in on as a fireman/ son, and how did he justify your presence therein?
I have examined some of the top male athletes at our local high school because they are friends of ours who asked me to look at their feet for one reason or another. It's interesting that you will often find limited ankle joint and 1st mpj dorsiflexion in some of these kids. This is probably due to their tendons and ligaments being stronger/tighter, thereby requiring more force to get the same rom. I remember one kid who was a quarterback, basketball player and pitcher who demonstrated severe hallux limitus. I doubt he could pitch or throw a football as well as he did without more dorsiflexion at these joints. These tighter tissue structures may be capable of storing more energy which might actually be an advantage.
The ten degrees of ankle dorsiflexion was a guide, not really an absolute. Certainly in individuals with a decreased range of dorsiflexion there in an increased tendency for compensation (earlier heel lift or stj pronation) than in those individuals with a greater rom.
The concept that the midtarsal joint has one position that is locked, that this "midtarsal joint locking" is able to occur with only a few pounds of force, and any plantar forefoot force past this "locked position of the midtarsal joint" will cause subluxation which is pathological is another of the things that I was taught that is erroneous.
Just because a plantar ligament has a nominal tension within it due to a nominal plantar forefoot loading force that causes the joints of the midtarsal joint midfoot to compress, this does not mean that increased plantar loading forces acting on the forefoot does not produce further motion and that this motion is not physiological.
How can one assume that the forces associated with running (i.e. 2.5-3.0 times body weight), which, by the way, is very much a physiological weightbearing activity of the human species, will produce the same dorsiflexion at the midfoot and midtarsal joints as does manual examination of the foot where the forces applied to the forefoot are at least 20 - 30 times less than those forces applied to the forefoot during manual examination of the foot?
The plantar ligaments and plantar tendons of the longitudinal arch of the foot are viscoelastic structures that will elongate more with increasing tension loading forces. Therefore, these structures must stretch more with increasing plantar forefoot loads which will, in turn, cause increased dorsiflexion motion of the forefoot at the midfoot and midtarsal joints. In other words, if only 10 pounds of manual force are applied to the plantar forefoot then the plantar ligaments will have approximately 20 times less force within them than if that patient were running. Anyone that has looked at a load deformation curve of any ligament from any animal from any scientific paper will know that a 20 time increase in ligament tension will cause an increase in length of that ligament.
In my opinion, one of the biggest problems that I will have in my remaining years as a podiatric biomechanics educator (I have been teaching biomechanics now for 29 years) is that I will need to try and "unteach" nearly every podiatrist in the United States, and many podiatrists abroad, that:
1) The midtarsal joint "locks
2) The midtarsal joint is "fully loaded" with only a few pounds of force
3) The midtarsal joint only pronates and supinates about two axes of motion
4) These two midtarsal joint axes are somehow simultaneously occurring axes.
Who is most responsible for promoting these erroneous ideas?
I will let you all decide.
Kevin Kirby, Jun 10, 2013
Craig:
If the things that Mert Root taught numerous times in the seminars I attended is not "Root Theory", then what, do you believe, is "Root theory"?
Remember, I heard Mert Root lecture, in person, probably at least 10-15 times between 1980-1995. He taught that the heel of the foot is easily bisectable, that the subtalar joint neutral position is the ideal functioning position of the subtalar joint and that orthoses should be made to "prevent compensation for foot deformities", including balancing the heel of the cast vertical for nearly all pathologies that he described.
Are you now saying this is not "Root theory"?
Don't get me wrong, I loved Mert Root. He was the greatest thing that happened to podiatry in the 1960s-1980s. However, for the sake of historical accuracy, let's not change what the man said and didn't say.....for whatever reason...??
You have likened the mtj to a spring. However, during the swing phase of gait the mtj is not anything like a spring. Don't you believe that you too are teaching erroneous concepts?
Jeff Root, Jun 10, 2013
Perhaps we should add the navicular and cuboid act as a single unit .
I still do not get why we are even looking at them as unit, when there has been show in bone pin studies that in the subjects tested there is motion during gait between the navicular and cuboid.
Why replace a false ie metatarsal joint locking with another false - the 2 bones act as a unit.
Being more precise and discussing the calcaneal-cuboid and talo-navicular and for that matter the navicular-cuboid joints.
For me would be a better step.
mike weber, Jun 10, 2013
Exactly increased energy storage, the interesting thing would be to know how much was developed or was genetic and thus gave them an advantage
I define "Root Theory" as the two postulates of subtalar joint neutral and the max pronated MTJ and what derives from that.
It is just that most of the critiques I see are not critiques of "Root Theory"; they are critiques of a piece of plastic that was molded over a cast of the foot taken in sublatar joint neutral in a way that was not described by Root!
CraigT Well-Known Member
Off track here but...
We know from fluoroscopic studies that elite high jumpers get mtj subluxation/deformation in the talonavicular joint of their plant foot just before takeoff
Do you know which study this is???
I have seen high speed video footage which which appears to show serious deformation, but I am not convinced that it is the foot- I though it was the shoe.
There is a flouroscopic study of high jumpers????
Craig Tanner
ASPETAR-
Qatar Orthopaedic and Sports Medicine Hospital
http://www.aspetar.com/
CraigT, Jun 10, 2013
Since when do the external and internal forces acting across the viscoelastic ligaments, tendons, muscles and bones of the foot stop acting like springs in the swing phase of gait? The foot is spring-like during swing phase and stance phase. The only difference between swing and stance phases is the magnitude of external forces acting across the joint axes of the foot. The foot does not stop behaving in a spring-like manner just because is has less external load acting on it during the swing phase of gait.
mike weber said: ↑
When you aren't in seeing patients in Sweden with bone pins in their feet, how would you be able to discriminate between the cuboid moving on the navicular with only skin markers on the midfoot?
It's all a question of modeling and how complex you want to make the model with the available data.
So making a vertically balanced thermoplastic foot orthosis with a 4 degree/4 degree rearfoot post that is intrinsically forefoot balanced and ends at the metatarsal necks should not be considered to be part of Root theory? This is what Mert Root taught in his classes should be the standard foot orthosis for all but a few special cases.
If this is not "Root theory", then who should we give credit to for making this the "standard" orthosis technique that was taught to me and thousands of other podiatry students both here in the US and abroad?
rdp1210 Active Member
Before making any replies off the cuff, I wanted a few days to just think about things.
One of the biggest questions that comes to mind is this:
How does your usual casting for orthotics procedure differ today from that which John Weed taught you?
I think your response to this will be most indicative of what you really believe.
Some important things to recognize in relation to your comments:
1) the osseous locking mechanism of Elftman was rejected by Root in 1975. I was an employee of Milt Wille at that point in time, when Wille challenged Root on this concept, and with experimentation, they showed it to be incorrect and Mert held up production of his volume 2 for 2 years. I will agree that use of the word "locking" is poorly chosen teminology, because the podiatric use of the term does not translate into the same meaning as the engineering use of the term. Please propose a new term to say that the ligaments begin to be stressed as they resist further abduction, eversion and dorsiflexion movements.
2) The exact synergy of all the ligaments in producing an EROM for the MTJ is still not fully understood. I know that Kiteoka has produced some work on this. I noted that Simon quoted part of the 2005 paper by Blackwood, however I would recommend that people read the full paper and not just the quotes he provided.
3) Yes, all the ligaments plantarly are viscoelastic. This means that they exhibit the properties of relaxation and creep. Each person probably exhibits different creep rates. Question is, how much creep do you allow for? And is the creep rate time dependent? I realize that these are questions that no one can answer for any one individual yet and is probably another reason why "X" amount of pronation produces symptoms in person and not another. When running, you may have 20x tension you mentioned, but these are brief time periods, so creep does not occur, vs. just standing. Root made a foot mold with the shape of the arch (medial and lateral) that it assumed when tension first began to occur in the ligaments. Because the orthotic flexes, no one has been able to tell us how much tension are in the MTJ ligaments in weightbearing on his device.
4) The MTJ 2 axis model was proposed by Hicks, not Root, so you may want to beat up Hicks more. In fairness to Root when he was doing the research that he published in his 1966 paper with Weed, et al., that they tried to replicate the Hicks experiment for both the STJ axis and the MTJ axes. They added a modification of the Manter experiment and felt that they had good replication of Hicks' STJ axis results, however they could not replicate the MTJ axis results. As a result they included nothing about MTJ axis in their 1966 paper. I am sure that John Weed related all this to you. I got the story from Mert himself. If you contact Tom Sgarlato, who was also an author, he'll also tell the same story. Root always knew that the 2 axis model was oversimplification, but he continued to teach it because he had nothing else to replace it with and it explained his tx modalities. He was very excited when I told him in the mid 80s that I believed the joint to be a nonorthogonal triaxial joint. I have not published anything on such because I haven't been able to put together equipment that would do the measuring I would like to do. I am writing the results of a research we did on sagittal plane angles with various forefoot-rearfoot alignments.
5) We probably need to be more correct by talking about degrees of freedom of motion of the MTJ than about axes. It is important that we not be confused by Nester's work in thinking that just because a joint has only one instantaneous axis of motion, that the motion of the joint can't be broken into it's component degrees of freedom. What I don't know is whether there is a greater amount of motion around the classical "OAMTJ" than can be created by adding together the motion around the vertical axis of motion and the transverse axis of motion. [In discussing the work of Nester, you need to think, what Nester would have found if he had been measuing the axis of the hip joint in gait? Would he have said that there is only one axis of motion instead of 3? It's a vector algebra problem.)
6) If there are indeed three axes of motion around the MTJ, (i.e. some type of ball-in-socket joint), is there any linkage of the motions? Why or why not? This is yet to be determined.
I appreciate your ambition to unteach everyone. I hope that by this posting you recognize my own cognition of the weaknesses of the Root Postulate. However when you start unteaching people, you have to have something to put in its place. (Here in Florida, we have this problem with such entities that they call sinkholes. You can step into one and never be found.) That's why I asked you the question above. Root certainly continued his MTJ teaching because he had nothing to put in its place. Guess that's why the CCPM started its biomx fellowship program, to train a new generation enough to get more research. There has been a limited amount of research into the MTJ, but a LOT more needs to be done, to fully understand the ligamentous interactions and the degrees of freedom of motion and the linkages of motion. It's easy to say someone is wrong. It's harder to find something better to replace those erroneous ideas with.
rdp1210, Jun 10, 2013
Similar Threads - Original Root Postulate
Availability of diabetes related foot health programs for Aboriginal and Torres Strait Islanders
NewsBot, Mar 19, 2019, in forum: Australia
How do I update an original Post eg Marketplace Threads
Hang Nguyen, Jun 24, 2018, in forum: Podiatry Arena Technical Support
SubmitKit
Aboriginal Medical Service - Cairns, Qld
JenniferC, Mar 14, 2017, in forum: Employment in Australia
JenniferC
REMOTE ABORIGINAL COMMUNITY WORK in ALICE SPRINGS
podiatry plus, Jun 23, 2015, in forum: Employment in Australia
podiatry plus
Aboriginal podiatry positions
maxants33, May 6, 2014, in forum: Australia
maxants33
Human foot not as unique as originally thought
NewsBot, Aug 21, 2013, in forum: General Issues and Discussion Forum
scotfoot
Henke's Original Paper on STJ Axis
mike weber, Nov 9, 2011, in forum: Biomechanics, Sports and Foot orthoses
Kevin Kirby


text:
Kenosha News will be sold to Lee Enterprises, owner of The Journal Times of Racine and Wisconsin State Journal
Lee Enterprises, owner of The Journal Times of Racine and Wisconsin State Journal, is buying the Kenosha News.
Kenosha News will be sold to Lee Enterprises, owner of The Journal Times of Racine and Wisconsin State Journal Lee Enterprises, owner of The Journal Times of Racine and Wisconsin State Journal, is buying the Kenosha News. Check out this story on jsonline.com: https://www.jsonline.com/story/money/business/2019/01/28/kenosha-news-sold-lee-enterprises/2701545002/
Rick Romell, Milwaukee Journal Sentinel Published 12:11 p.m. CT Jan. 28, 2019 | Updated 1:08 p.m. CT Jan. 28, 2019
Lee Enterprises Inc. has agreed to buy the Kenosha News. Lee already owns The Journal Times of Racine and the Wisconsin State Journal. (Photo: Lee Enterprises Inc.)
Lee Enterprises Inc., owner of The Journal Times of Racine, the Wisconsin State Journal and other Wisconsin newspapers, has agreed to buy the Kenosha News.
United Communications Corp., owner of the Kenosha News, also will sell the Lake Geneva Regional News to Lee.
No sale price was disclosed. The transaction is expected to be completed Thursday.
LIKE US ON FACEBOOK: Get Journal Sentinel business news in your feed
The Kenosha News publishes seven days a week and has an average daily print circulation of about 20,000, Lee said in announcing the deal. The Lake Geneva Regional News publishes weekly.
The acquisition will add to Lee's earnings in the first year, Kevin Mowbray, CEO and president of Davenport, Iowa-based Lee, said in a statement.
Subscribe to get the BusinessWatch email newsletter.
Lee owns 46 daily newspapers and holds a joint interest in two others, along with digital products and nearly 300 specialty publications in 21 states. The firm's newspapers have circulation of 900,000 daily and 1.4 million on Sunday. Its digital sites attract more than 25 million unique visits monthly, according to the company's website.
Lee's other Wisconsin newspapers include the La Crosse Tribune and daily papers in Beaver Dam, Portage, Baraboo and Chippewa Falls.
Top Headlines from Business:
Subscriber exclusive: Milwaukee's most important commercial development trends of the past decade extend beyond downtown
Independent booksellers persevere despite Amazon, rising costs
FOLLOW JS BUSINESS: Facebook | Twitter | LinkedIn
Read or Share this story: https://www.jsonline.com/story/money/business/2019/01/28/kenosha-news-sold-lee-enterprises/2701545002/
Viking adding Great Lakes cruises that will start or end in Milwaukee
What's happening with the 6 high rise towers planned for downtown Milwaukee?
New apartments still draw renters, but growth is slowing
Giannis jersey sales jump as MVP enjoys another strong season
What we know now about the 2020 DNC security zone in downtown
Architect Chris Gallagher, of Eppstein Uhen, dies


The Ecole Mountview School app is here! The app is available on iPhone and Android devices under Ecole Mountview Elementary and it is free to download. The app is your direct link to school news, calendar events, and days off. You can even report your child's absence with a few simple clicks. As well, you can view the school's Twitter and Facebook feeds even if you do not have an account with these services. Download it today!


This dataset contains all the available data on Basic Savings Bank Deposit Accounts (BSBDA), by year. Available metrics include total number of BSBDA accounts, total amount of BSBDA deposits, number of BSBDA opened through branches, number of BSBDA opened through banking correspondents (BCs), deposits of BSBDA through branches, and deposits of BSBDA through BCs. Data is as reported by the Reserve Bank of India (RBI).


This is the title of Chapter 1 of D.A. Carson's book A Call to Spiritual Reformation.
Let me briefly list the eight lessons he gives to shape a successful prayer life.
1) Much praying is not done because we do not plan to pray.
- Wise planning will ensure that we devote ourselves to prayer often, even if for brief periods: it is better to pray often with brevity than rarely but at length.
2) Adopt practical ways to impede mental drift.
- You can do many things to stamp out daydreaming, to stifle reveries. One of the most useful things is to vocalize your prayers....It simply means you articulate your prayers, moving your lips perhaps; the energy devoted to expressing your thoughts in words and sentences will order and discipline your mind and help deter meandering.
3)At various periods in your life, develop, if possible, a prayer-partner relationship.
- ...Praying is an immensely intimate business--and intimacy in one area leads to intimacy in other areas, [so choose an appropriate partner]. Prayer partners are as valuable for the discipline, accountablity, and regularity they engender as for the lessons that are shared.
4)Choose models--but choose them well.
-Most of us can improve our praying by carefully, thoughtfully listening to others pray. All[good models] are characterized by a wonderful mixture of contrition and boldness in prayer.
5) Develop a system for your prayer lists.
- Many Christians who give themselves to prayer, however find that in addition to such published information[i.e. Operation World], it is wise and fruitful to prepare their own lists.
6) Mingle praise, confession, and intercession; but when you intercede, try to tie as many requests as possible to Scripture.
-This rich mixture is nothing more than a reflection of the many different components of the kind of relationship we ought to have with the God of the Bible.
7)If you are in any form of spiritual leadership, work at your public prayers.
- It is not a question of pleasing our human hearers, but of instructing them and edifying them. Good praying is more easily caught than taught.
8) Pray until you pray.
-We are especially prone to such feelings when we pray for only a few minutes, rushing to be done with mere duty. To enter the spirit of prayer, we must stick to it for a while. If we "pray until we pray", eventually we come to delight in God's presence, to rest in His love, to cherish His will.


text:
Lost In The Light
Play track
Set as current obsession
Go to artist profile
Join others and track this song
Play album
Replace video
So if someone could see me now
Do you know any background info about this track? Start the wiki
radio paradise
watch over me
Barchords
13 more albums featuring this track
Sunday Best
Similar Tracks
Patrick Watson
Alexi Murdoch
Naked as We Came
All My Days
Dawning On Me
Thursday 28 July 2022 310
Friday 29 July 2022 301
Saturday 30 July 2022 312
Sunday 31 July 2022 296
Monday 1 August 2022 294
Tuesday 2 August 2022 275
Wednesday 3 August 2022 293
Thursday 4 August 2022 288
Friday 5 August 2022 282
Saturday 6 August 2022 315
Sunday 7 August 2022 301
Wednesday 10 August 2022 311
Thursday 11 August 2022 318
Friday 12 August 2022 295
Saturday 13 August 2022 319
Sunday 14 August 2022 295
Monday 15 August 2022 285
Tuesday 16 August 2022 306
Thursday 1 September 2022 293
Friday 2 September 2022 269
Saturday 3 September 2022 304
Sunday 4 September 2022 326
Monday 5 September 2022 313
Tuesday 6 September 2022 290
Wednesday 7 September 2022 314
Saturday 10 September 2022 294
Sunday 11 September 2022 301
Monday 12 September 2022 315
Tuesday 13 September 2022 337
Wednesday 14 September 2022 336
Thursday 15 September 2022 332
Friday 16 September 2022 331
Saturday 1 October 2022 397
Sunday 2 October 2022 368
Monday 3 October 2022 373
Tuesday 4 October 2022 389
Wednesday 5 October 2022 355
Thursday 6 October 2022 340
Friday 7 October 2022 375
Monday 10 October 2022 374
Tuesday 11 October 2022 372
Wednesday 12 October 2022 329
Thursday 13 October 2022 351
Friday 14 October 2022 338
Saturday 15 October 2022 342
Sunday 16 October 2022 358
Tuesday 1 November 2022 336
Wednesday 2 November 2022 356
Thursday 3 November 2022 342
Friday 4 November 2022 353
Saturday 5 November 2022 394
Sunday 6 November 2022 314
Monday 7 November 2022 340
Thursday 10 November 2022 323
Friday 11 November 2022 390
Saturday 12 November 2022 436
Sunday 13 November 2022 381
Monday 14 November 2022 380
Tuesday 15 November 2022 365
Wednesday 16 November 2022 390
Thursday 1 December 2022 365
Friday 2 December 2022 381
Saturday 3 December 2022 385
Sunday 4 December 2022 386
Monday 5 December 2022 396
Tuesday 6 December 2022 376
Wednesday 7 December 2022 376
Saturday 10 December 2022 355
Sunday 11 December 2022 310
Monday 12 December 2022 319
Tuesday 13 December 2022 364
Wednesday 14 December 2022 368
Thursday 15 December 2022 368
Friday 16 December 2022 345
Sunday 1 January 2023 414
Monday 2 January 2023 412
Tuesday 3 January 2023 402
Wednesday 4 January 2023 380
Thursday 5 January 2023 402
Friday 6 January 2023 413
Saturday 7 January 2023 425
Tuesday 10 January 2023 432
Wednesday 11 January 2023 425
Thursday 12 January 2023 414
Friday 13 January 2023 418
Saturday 14 January 2023 458
Sunday 15 January 2023 412
Monday 16 January 2023 445
Play this track
Apple Music Apple Music
afiesongs.tripod.com
Twitter (@bahamasmusic)
Facebook (bahamasmusic)
Artist images
Bahamas is Canadian musician Afie Jurvanen (born April 28, 1981, in Toronto). Jurvanen isn't from the Bahamas; he's a Finnish-Canadian raised in Barrie (a working class town in rural Ontario). Since 2009 he's been making music under the name Bahamas–writing songs about sunsets, love affairs, and making out with crooked smiles. Through simple arrangements, he charts an escape route from the snow belt to the coral reefs. His album, Barchords, was released in 2012 to critical praise: "Barchords is a gorgeous, full-bodied recording that revels in spare but intensely flavorful… read more
Bahamas is Canadian musician Afie Jurvanen (born April 28, 1981, in Toronto). Jurvanen isn't from the Bahamas; he's a Finnish-Canadian raised in Barrie (a working class town in rural Ontari… read more
Bahamas is Canadian musician Afie Jurvanen (born April 28, 1981, in Toronto). Jurvanen isn't from the Bahamas; he's a Finnish-Canadian raised in Barrie (a working class town in rural Ontario). Since 2009 he's been making music under th… read more
View full artist profile
Leif Vollebekk
Langhorne Slim
Nathaniel Rateliff
1,286,137 listeners


text:
Chinese carmaker BYD operates a manufacturing plant in Lancaster, California. Photo: Xinhua
Christine Loh and Christopher Tang
Rather than decouple, China and the US must find ways to coexist
Clear thinkers in China know a bitter divorce from the US is a lose-lose situation
Beijing could instead seek healthy competition and cooperation with the US, expand operations of Chinese brands in America, and aim to be more transparent
Published: 3:00am, 21 Jun, 2020
Updated: 3:30am, 21 Jun, 2020
Christine Loh
Christine Loh is chief development strategist and adjunct professor at the Hong Kong University of Science and Technology's Institute of the Environment and Division of Environment and Sustainability. She was the former undersecretary for the environment (2012-17), and a former lawmaker. She is also the former CEO of Civic Exchange, a non-profit public policy think tank. She is a lawyer by training, a commodities trader by profession, and an author of many publications.
Christopher Tang
Christopher Tang is university distinguished professor and Edward Carter professor of business administration at the UCLA Anderson School of Management.


Authentic used burlap coffee bags are approximately 28" x 40", each bag may be a top cut or a side cut and may contain different design/prints and marked with its country of origin, and may have lingering residue, dirt, stains, or odors associated from the transport and storage of coffee beans. These used burlap bags are bio-degradable and environmentally friendly and offer that rich wholesome coffee scent as well as the natural burlap scent. Burlap coffee bags have multipe uses such as decor or craft projects, for gardening as a biodegradeable weed barrier, table cloth, wall or ceiling decoration, packing protection, and much more. Coffee bag prints may differ from the photo provided.