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Anatomically contoured anterior cervical plates with bone ingrowth surfaces, providing for intersegmental compressive preloading, and a rigid and locked interface to all of the bone screws, with those engaging the vertebrae deployed in highly convergent pairs. The bone screws have a tapered self-tap

Anatomically contoured anterior cervical plates with bone ingrowth surfaces, providing for intersegmental compressive preloading, and a rigid and locked interface to all of the bone screws, with those engaging the vertebrae deployed in highly convergent pairs. The bone screws have a tapered self-tapping leading end, an increasing root diameter with a generally constant outer diameter with a thread that is narrow and sharp throughout and an enlarged head portion capable of an interference fit to the receiving holes of the plate. Instrumentation consists of plate holders, a compression apparatus and a pilot hole forming device that interlocks with the plate. Methods for spinal compression and bone hole preparation are provided.

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Anatomically contoured anterior cervical plates with bone ingrowth surfaces, providing for intersegmental compressive preloading, and a rigid and locked interface to all of the bone screws, with those engaging the vertebrae deployed in highly convergent pairs. The bone screws have a tapered self-tap

Anatomically contoured anterior cervical plates with bone ingrowth surfaces, providing for intersegmental compressive preloading, and a rigid and locked interface to all of the bone screws, with those engaging the vertebrae deployed in highly convergent pairs. The bone screws have a tapered self-tapping leading end, an increasing root diameter with a generally constant outer diameter with a thread that is narrow and sharp throughout and an enlarged head portion capable of an interference fit to the receiving holes of the plate. Instrumentation consists of plate holders, a compression apparatus and a pilot hole forming device that interlocks with the plate. Methods for spinal compression and bone hole preparation are provided. mechanical linkage are housed within the sealed chamber. 9. The valve of claim 2 wherein the fail safe assembly selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetostrictive device is operable upon the mechanical linkage such that upon engagement, a movable member of the mechanical linkage is locked into place. 10. The valve of claim 2 wherein the fail safe assembly selected from the group consisting of a magnetorheological device and an electrorheological device is operable upon the mechanical linkage such that upon engagement, a movable member of the mechanical linkage is locked into place. 11. The valve of claim 2 wherein the incompressible fluid is selected from the group consisting of a magnetorheological fluid and an electrorheological fluid, and the fail safe assembly further comprising a field generating means selected respectively from the group consisting of a means for applying a magnetic field to the magnetorheological fluid or a means for applying an electrical field to the electrorheological fluid, the field generating means being configured such that upon application of the respective field a moving member of the mechanical linkage is locked into place. 12. The valve of claim 1 wherein the fail safe assembly further comprises an electromagnetic clutch and an anti-backdrive device connected to and positioned between the pressure balanced drive assembly and the bore closure assembly. 13. The valve of claim 12 wherein the anti-backdrive device is selected from the group consisting of a sprag clutch, a non-backdriveable gear reducer, an electromagnetic brake, a spring-set brake, a permanent magnet brake on the electric motor, a means for holding power on the electric motor, a locking member, a piezoelectric device, and a magnetorheological (MR) device. 14. The valve of claim 13 wherein the anti-backdrive device is a locking member selected from the group consisting of a latch, a cam, a pin, and a wrap spring. 15. The valve of claim 1 wherein the fail safe assembly further comprises a locking member selected from the group consisting of a latch, a cam, a pin, and a wrap spring. 16. The valve of claim 1 wherein the fail safe assembly is selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetostrictive device. 17. The valve of claim 1 wherein the fail safe assembly is selected from the group consisting of a magnetorheological device and an electrorheological device. 18. The valve of claim 1 wherein the bore closure assembly further comprises a flapper valve, the flapper valve being held in the open position by a flow tube. 19. The valve of claim 18 further comprising a feedback loop sensing the position of the flow tube and communicating the position to the drive assembly. 20. The valve of claim 1 wherein the bore closure assembly further comprises a ball valve. 21. The valve of claim 20 further comprising a feedback loop sensing the position the ball valve and communicating the position to the drive assembly. 22. The valve of claim 1 further comprising a means for sensing the position of the bore closure assembly and communicating the position to the drive assembly. 23. The valve of claim 22 wherein the sensing means is an electrical current monitor monitoring the drive assembly, wherein a spike in current indicates that the drive assembly has driven the bore closure assembly to a limit. 24. The valve of claim 22 wherein the sensing means is driving cycle counter monitoring the drive assembly, wherein the number of driving cycles is calibrated to the position of the bore closure assembly. 25. The valve of claim 1 wherein the hold signal consumes less than about 10 watts. 26. The valve of claim 25 wherein the hold signal is transmitted through a wire. 27. The valve of claim 25, wherein the hold signal is a wireless transmission. 28. The valve of claim 1 wherein the valve closes in less than about 5 seconds upon interruptio n of the hold signal. 29. The valve of claim 1 wherein the valve is insensitive to the depth at which it is installed in the well. 30. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; and wherein the pressure balanced drive assembly comprises a hydraulic actuator coupled to the bore closure assembly by a mechanical linkage and is configured such that the driving force need only overcome the resistance force that normally biases the bore closure assembly to the closed position. 31. The valve of claim 30 wherein the mechanical linkage further comprises a shaft. 32. The valve of claim 31 wherein the hydraulic actuator further comprises an electric pump for pumping the incompressible fluid in a hydraulic loop and applying a driving force to the shaft and a control valve for regulating the pressure in the hydraulic loop. 33. The valve of claim 32 wherein the control valve is selected from the group consisting of a solenoid valve, a spring-biased check valve, and a flow switch. 34. The valve of claim 33 wherein the incompressible fluid is selected from the group consisting of a magnetorheological fluid and an electrorheological fluid and wherein the flow switch respectively applies a magnetic field to the magnetorheological fluid or an electrical field to the electrorheological fluid such that upon application of the respective filed a moving member of the shaft is locked into place. 35. The valve of claim 32 wherein power is supplied to the electric pump by inductive coupling. 36. The valve of claim 32, wherein the hydraulic actuator and at least a portion of the shaft are housed within a sealed chamber filled with an incompressible fluid and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one piston connected to the sealed chamber. 37. The valve of claim 32 wherein the hydraulic actuator is housed within a sealed chamber filled with an incompressible fluid and the shaft is not housed within the scaled chamber, and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one piston connected to the sealed chamber. 38. The valve of claim 30 wherein the hydraulic actuator and at least a portion of the mechanical linkage are housed within a sealed chamber filled with an incompressible fluid and the pressure of the incompressible fluid is balanced with thc wellbore pressure by at least one piston connected to the sealed chamber. 39. The valve of claim 8 wherein the fail safe assembly further comprises a locking member selected from the group consisting of a latch, a cam, a pin, and a wrap spring. 40. The valve of claim 30 wherein the fail safe assembly selected from the group consisting of a magnetorheological device and an electrorheological device is operable upon the mechanical linkage such that upon engagement, a movable member of the mechanical linkage is locked into place. 41. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for drivi ng the bore closure assembly to an open position; the fail sate assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly comprises a hydraulic actuator coupled to the bore closure assembly by a mechanical linkage and wherein the hydraulic actuator and at least a portion of the mechanical linkage are housed within a sealed chamber filled with an incompressible fluid and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one bellows connected to the scaled chamber. 42. The valve of claim 41 wherein the incompressible fluid is selected from the group consisting of a magnetorheological fluid and an electrorheological fluid, and the fail safe assembly further comprising a field generating means selected respectively from the group consisting of a means for applying a magnetic field to the magnetorheological fluid or a means for applying an electrical field to the electrorheological fluid, the field generating means being configured such that upon application of the respective field a moving member of the mechanical linkage is locked into place. 43. A fail-sale, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly comprises a hydraulic actuator coupled to the bore closure assembly by a mechanical linkage; wherein the mechanical linkage further comprises a shaft; wherein the hydraulic actuator further comprises an electric pump for pumping the incompressible fluid in a hydraulic loop and applying a driving force to the shaft and a control valve for regulating the pressure in the hydraulic loop; and wherein the hydraulic actuator and an least a portion of the shall are housed within a scaled chamber filled with an incompressible fluid and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one bellows connected to the sealed chamber. 44. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly the driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly comprises a hydraulic actuator coupled to the bore closure assembly by a mechanical linkage; wherein the mechanical linkage further comprises a shaft; wherein the hydraulic actuator further comprises an electric pump for pumping the incompressible fluid in a hydraulic loop and applying a driving force to the shaft and a control valve for regulating the pressure in the hydraulic loop; and wherein the hydraulic actuator is housed within a sealed chamber filled with an incompressible fluid and the shaft is not housed within the sealed chamber, and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one bellows connected to the sealed chamber. 45. The valve of claim 44, wherein the incompressible fluid is selected from the group consisting of a magnetorheological fluid and an electrorheological fluid, and the fail safe assembly further comprising a field generating means selected respectively from the group consisting of a means for applying a magnetic field to the magnetorheological fluid or a means for applying an electrical field to the electrorheological fluid, the field generating means being configured such that upon application of the respective field a moving member of the mechanical linkage is locked into place. 46. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly further comprises an electric motor coupled to the bore closure assembly by a mechanical linkage; wherein the fail safe assembly selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetorestrictive device is operable upon the mechanical linkage such that upon engagement, a movable member of the mechanical linkage is locked into place; and wherein the fail safe assembly selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetostrictive device further comprises a band surrounding the movable member and at least one end of the band connected to a deformable member selected respectively from the group consisting of a piezoelectric stack, an electrostrictive stack, and a magnetostrictive actuator, the deformable member having an electrical connection, the fail safe assembly being configured such that upon application of an electrical signal to the electrical connection, the deformable member deforms, thereby tightening the band around the movable member and locking the movable member into place against a stator. 47. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly comprises a hydraulic actuator coupled to the bore closure assembly by a mechanical linkage; and wherein the fail safe assembly selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetostrictive device further comprises a band surrounding the movable member and at least one end of the band connected to a deformable member selected respectively from the group consisting of a piezoelectric stack, an electrostrictive stack, and a magnetostrictive actuator, the deformable member having an el ectrical connection, the fail safe assembly being configured such that upon application of an electrical signal to the electrical connection, the deformable member deforms, thereby tightening the band around the movable member and locking the movable member into place against a stator. 48. A fail-safe, surface controlled subsurface safety valve for use in a well, comprising: a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly; the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position; the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal; wherein the pressure balanced drive assembly further comprises a linear induction motor generating a magnetic field that actuates the bore closure assembly; and wherein the fail safe assembly selected from the group consisting of a piezoelectric device, an electrostrictive device, and a magnetostrictive device further comprises a band surrounding the movable member and at least one end of the band connected to a deformable member selected respectively from the group consisting of a piezoelectric stack, an electrostrictive stack, and a magnetostrictive actuator, the deformable member having an electrical connection, the fail safe assembly being configured such that upon application of an electrical signal to the electrical connection, the deformable member deforms, thereby tightening the band around the movable member and locking the movable member into place against a stator. nation when turned on; a power source connected to said light source and capable of supplying sufficient power to cause it to provide the illumination; a switch connected to said power source and responsive to each impact of said footwear against a surface, said switch producing for each said impact a series of electrical pulses the number of said pulses varying with the force of said impact; a circuit connected to receive said electrical pulses connected to said light source to cause said light source to produce a series of light flashes, the number of which varies with the magnitude of said force. 8. The lighting system of claim 7 further comprising a counter circuit responsive to the initiation of pulses from said switch counting a given number of said pulses and for disconnecting said circuit from said light source after said given number of pulses have been counted. 9. The lighting system of claim 7 wherein said circuit includes a synchronous timer and said light source comprises a plurality of separate light sources connected to said synchronous timer which flash in sequence based on the number of pulses in said pulse output. 10. The lighting system of claim 7 wherein said switch is a spring switch. 11. The lighting system of claim 7 wherein at least some of said light sources are light-emitting diodes. 12. A lighting system for incorporating in footwear comprising; at least one light source located so as to be visible on an external surface of said footwear; a power source connected to said light source capable of providing sufficient power to cause illumination of said light source; a switch connected to said power source and responsive to impact of said footwear against a surface, said switch producing for each impact a series of electrical pulses in which the number of pulses varies with the magnitude of said impact; a divider circuit connected to receive said series of electrical pulses producing electrical output pulses the number of which vary with the pulse output of said switch; and a synchronous timer connected to receive the output of said divider circuit connected to said light source to cause said light source to produce a series of light flashes, the number of which varies with the magnitude of said impact. 13. The lighting system of claim 12 further comprising a timer circuit responsive to the initiation of pulses from said switch for resetting said synchronous timer after a set time period. 14. The lighting system of claim 12 wherein said switch is a spring switch. ver further having at least one reflector portion extending between the housing the lighting element. The electrical power sockets of the light fixture are configured to such that the lighting element extends further away from the housing than the raised portion of the ballast cover. A cross-sectional geometry of the ballast is sufficiently arcuate such that light from the lighting element is substantially equally downwardly distributed from the light fixture. cement sleeve through said dogs to pack off said pack off assembly; reverse circulating said system to remove excess cement from said junction. 12. A method as claimed in claim 11 wherein said method includes removing said system from said wellbore. le periods, wherein the duration of each sample period is shorter than one half of the time required for the tool to complete a rotation; measuring the azimuthal angle of the detector in at least one sample period; sorting the samples into a plurality of groups, each group representing the azimuthal sector of the borehole from which each sample was detected; within a group, calculating the mean of the samples; within a group, calculating a theoretical standard deviation of the samples; within a group, calculating an actual standard deviation of the samples; within a group, mathematically weighting each of the samples according to the deviation of the sample from the mean and mathematically summing the weighted samples to produce a weighted sample total for a sector; within a group, dividing the weighted sample total by the total duration of sample periods in the group to determine an detection rate for the sector; and transforming the detection rate for at least one sector into a representation of at least one formation characteristic. 12. The method of claim 11 further comprising: within a group, if the ratio of the actual standard deviation to the theoretical standard deviation is below a given value, mathematically summing the samples to achieve a sample total for a sector; and within a group, dividing the weighted sample total by the total duration of sample periods in the group to determine a count rate for the sector. 13. The method of claim 11 further comprising transforming the detection rate for at least two of the sectors into the same formation characteristic to produce an image of the borehole with respect to the formation characteristic. 14. The method of claim 11 further comprising transforming the detection rate for one or more sectors into a representative formation characteristic of the borehole. 15. The method of claim 11 wherein the emitter emits gamma radiation and the detectors detect counts of back-scattered gamma radiation. 16. The method of claim 15 wherein the at least one formation characteristic comprises density. 17. The method of claim 15 wherein the at least one formation characteristic comprises a lithology indicator. 18. The method of claim 11 wherein the step of sorting the samples into a plurality of groups comprises sorting the samples into sixteen groups. 19. The method of claim 11 wherein the duration of each sample period is shorter than the time that the detector is in the azimuthal sector in one rotation of the tool. 20. The method of claim 11 wherein the energy is detected in a first energy interval and a second energy interval during the sample periods; wherein the steps of mathematically weighting each of the samples according to standoff, mathematically summing the weighted samples, and dividing the weighted sample total by the total duration of the sample periods are performed with respect to the first energy interval and then with respect to the second energy interval; and wherein transforming the detection rate for at least one sector comprises transforming the detection rate for at least one energy interval for at least one sector into a representation of at least one formation characteristic. ined on the related tubular joint body. The tubular joint bodies are precision machined to be connected by male and female threads granting an exact alignment of all slots in the blast joint(s) and allowing any combination of lengths for coping with any required assembly. id second set of first and second columns and rotatable around the horizontal axis of rotation, said first crosshead and said second crosshead being rotatable synchronously, said crossheads being synchronously adjustable in height; a front conveyor ending in front of the processing station, said front conveyor ending adjacent to said first crossheads above the lowered adjacent crosshead and the lowered mounting frames; a rear conveyor ending behind the processing station, said rear conveyor ending adjacent to said second crossheads above the lowered adjacent crosshead and the lowered mounting frames; an additional conveyor arranged between said front conveyor and said rear conveyor, said additional conveyor being raisable and lowerable; and a motor vehicle mounting part connected to said first and second crossframes and rotatable around a horizontal axis of rotation, said mounting part comprising two mounting frames arranged at mutually spaced locations from one another, a mutual distance between each first and second column of said sets of columns being greater than a width of said motor vehicle part or a width of said mounting part. 10. A processing station in accordance with claim 9, wherein one column of a set of columns associated with each crosshead is a drive column and the other column of a set of columns associated with each crosshead is a guide column. 11. A processing station in accordance with claim 9, wherein said additional conveyor extends only between the ends of said mounting frames. 12. A processing station in accordance with claim 9, wherein said additional conveyor extends into an area of said mounting frames and has end-side openings for the passage of said mounting frames during a relative movement between said mounting frame and said conveyor. 13. A processing station in accordance with claim 9, wherein said rear conveyor is a roller conveyor and said front conveyor is a roller conveyor.