Abstract: An improved dental procedure and apparatus where ultraviolet radiation pulses are used to etch selectively both hard tissue and soft tissue in dental procedures. There exists distinct ablation thresholds for hard and soft tissue which are dependent on the material being ablated for a given wavelength of the ultraviolet radiation. Sufficient differences in ablation threshold exist for enamel, dentin, and carious material, thereby allowing dentists to perform both hard tissue and soft tissue procedures without excess damage of healthy enamel, dentin or other pulp structures.

Abstract: An improved dental procedure and apparatus where ultraviolet radiation pulses are used to etch selectively both hard tissue and soft tissue in dental procedures. There exists distinct ablation thresholds for hard and soft tissue which are dependent on the material being ablated for a given wavelength of the ultraviolet radiation. Sufficient differences in ablation threshold exist for enamel, dentin, and carious material, thereby allowing dentists to perform both hard tissue and soft tissue procedures without excess damage to healthy enamel, dentin or other pulp structures.

Abstract: A cryptographic key recovery system for generating a cryptographic key for use by a pair of communicating parties while simultaneously providing for its recovery using one or more key recover agents. A plurality of m-bit shared key parts (P, Q) are generated which are shared with respective key recovery agents, while an n-bit nonshared key part (R) is generated that is not shared with any key recovery agent. The shared key parts (P, Q) are combined to generate an m-bit value which is concatenated with the nonshared key part (R) to generate an (m+n)-bit value from which an encryption key is generated. The cryptographic system has the effective work factor of an n-bit key to all of the key recovery agents acting in concert, but has the effective work factor of an (m+n)-bit to any other combination of third parties.

Abstract: A cryptographic key recovery system that is interoperable with existing systems for establishing keys between communicating parties. The sender uses a reversible key inversion function to generate key recovery values P, Q and (optionally) R as a function of a session key and public information, so that the session key may be regenerated from the key recovery values P, Q and (if generated) R. Key recovery values P and Q are encrypted using the respective public recovery keys of a pair of key recovery agents. The encrypted P and Q values are included along with other recovery information in a session header accompanying an encrypted message sent from the sender to the receiver. The key recovery agents may recover the P and Q values for a law enforcement agent by decrypting the encrypted P and Q values in the session header, using their respective private recovery keys corresponding to the public keys.

Abstract: An improved dental procedure and apparatus where ultraviolet radiation pulses are used to etch selectively both hard tissue and soft tissue in dental procedures. There exists distinct ablation thresholds for hard and soft tissue which are dependent on the material being abated for a given wavelength of the ultraviolet radiation. Sufficient differences in ablation threshold exist for enamel, dentin, and carious material, thereby allowing dentists to perform both hard tissue and soft tissue procedures without excess damage to healthy enamel, dentin or other pulp structures.

Abstract: Method for providing user authentication and a memory for storing a computer program for providing user authentication are described. The method includes the steps of providing a first argument including a one-way cryptographic transformation of a password and a second argument including a one-way cryptographic transformation of a cryptographic combination of the password and a first nonce, computing a first term using the first argument and computing a second term using the first nonce, and comparing the second term with the second argument.

Abstract: A pattern reproduction table incorporates a support grid which supports a transparent perforated sheet above a plurality of lamps. The support grid comprises a plurality of thin polished longitudinal and transverse members which are interlocked and which are mounted in tension on an enclosure. The support grid provides rigid support for the transparent perforated sheet without obscuring the lamps or interfering with a vacuum blower which is mounted in the enclosure.

Abstract: A multiple pattern grading machine includes an open, horizontally-disposed support frame within which a table is movably mounted by means of parallelogram linkages connecting the opposite ends of the table to the adjacent ends of the support frame. The parallelogram linkages also mount a plurality of channel bars arranged in corresponding pairs at opposite ends of the table, each corresponding pair of channel bars being adapted to mount a sheet of pattern reproducing paper therebetween, with the paper sheets arranged in a superimposed stack across the table. A selected pair of channel bars mounts a rigid grid for mounting master pattern sections located above the uppermost sheet in such a manner that each of the pattern reproducing sheets and the master pattern sections are moved relative to one another in varying increments of distance when the table is manually moved in the frame.

Abstract: In a cutting board assembly having a clamp bar operated by a foot pedal mechanism for clamping papers or similar materials to the board for cutting, means are provided for accurately aligning guide markings on the paper with the cutting edge of the board. Such means include an aligning strip secured to the under surface of the clamp bar and projecting therefrom, with the straight edge of the projecting portion of the strip registering with the cutting edge of the board, whereby the markings on the paper can be visually aligned with the straight edge of the strip and therefore with the cutting edge of the board for accurate cutting. The aligning strip may be made of transparent material or of opaque material provided with apertures through which the markings can be seen. The foot pedal mechanism is also provided with adjustable stop means which limits upward travel of the clamp bar so that the aligning strip is maintained close to the paper to be cut for accurate alignment of the markings thereon.