Abstract: A modified or isolated composition comprising a gel. The gel includes a plurality of first polymers, each of said first polymers having first functional groups comprising a first nucleic acid sequence attached as side-chains thereto. The gel includes a plurality of second polymers, each of said second polymers having second functional groups comprising a second nucleic acid sequence attached as side-chains thereto, said first and said second functional groups forming a reversible cross-link between said first and said second polymers, wherein said cross-link comprises a plurality of hydrogen bonds between complementary base portions of said first and said second nucleic acid sequences.

Abstract: A composition that comprises a first polymer having first functional groups attached as side-chains thereto. The composition further comprises a second polymer having second functional groups attached as side-chains thereto. The first and the second functional groups are capable of reversibly forming a cross-link between the first and the second polymers.

Abstract: The present invention provides a composition comprising a first polymer and a second polymer cross-linked by the association of functional groups attached as side chains to the polymers.

Abstract: This invention is an oligomer-based analog neural network (ANN) comprising weight and saturation oligomers, the concentrations of which are selected such that activation of the ANN by a set of input oligomers generates a set of output oligomers, the sequences and relative concentrations of which are dependent on the sequences and relative concentrations of the input oligomers. The invention further includes methods for using such an ANN for solving any problems amenable to solution by a trained neural network. A preferred embodiment of the claimed invention is a DNA-based ANN that accepts cDNA molecules as inputs and analyzes the gene expression profile of the cells from which the cDNA is derived. The DNA-based ANN is typically trained with a computer to identify the weights giving accurate mapping of the inputs to the outputs; and the concentrations of weight oligomers of the DNA-based ANN are then selected accordingly.

Abstract: A method and apparatus for temperature compensation of a resistive based Read-Only Memory device is disclosed. In accordance with the method of the invention, the input voltage supplied to ROM device is adjusted in response to changes in temperature to maintain the current through the ROM at a substantially constant level even as the resistivity of the temperature-dependent connection resistors changes. In one embodiment of the invention, the voltage across the reference resistor is determined by providing a constant current source to the reference resistor and this voltage level is applied to the input of the ROM device. The reference resistor is selected to have similar properties of conductivity as those of the data resistor, for example, a polysilicon. As the temperature increases, the resistivity of a polysilicon data resistor and resistor decrease in a similar manner and, accordingly, the voltage across the reference resistor also decreases.

Abstract: The present invention is directed to an analog, oligomer-based method for determining a mathematical result of carrying out an operation of matrix algebra on input data. The method comprises representing at least one m-component vector V=&Sgr;iViei by a set of single-stranded oligomers Ei and Ei which are in 1:1 correspondence with the basis vectors ei, i=1, 2, . . . , m in an abstract m-dimensional vector space. A composition comprising at least one set of oligomers Ei and Ei representing the components of a vector is obtained as input date and is subjected to at least one physical or chemical treatment having an effect on the oligomers that is an analog representation of an operation of matrix algebra. The method can be used to represent the operations of a neural network; for example, to produce a content-addressable memory, or a multilayer perceptron.

Abstract: The rate of nucleic acid strand exchange can be greatly enhanced if one of the strands of a double-stranded nucleic acid oligomer has a single-stranded extension, or “toehold,” to which a complementary, single-stranded, nucleic acid oligomer can bind. Toehold-facilitated strand exchange makes possible the controlled addition and removal of one nucleic acid strand from a second, complementary strand. Oligomers are designed and used to carry out controlled, repetitive nucleic acid structural transitions mediated by hybridization and toehold-facilitated strand exchange reactions, which in turn control the operation of a nanomachine or a 2-state molecular switch.

Abstract: The present invention is directed to methods for (a) encrypting information in the form of words, numbers, or graphical images, by obtaining a set of nucleic acid strands or nucleic acid analog strands having subunit sequences selected to represent the information, (b) transmitting the information by sending the nucleic acids or nucleic acid analogs to a recipient who possesses a key for decryption, and (c) using the key to decrypt the information and recover the words, numbers, or represented by the nucleic acids or nucleic acid analogs.

Abstract: The present invention is directed to a method for providing oligonucleotides or oligonucleotide analogs having known subunit sequences in which the desired oligomers are released from selected storage sites in one, two, or three dimensions, on a substrate by locally denaturing double-stranded complexes at the storage sites containing the desired oligomers. The released oligomers are useful in schemes for determining solutions to mathematical problems, in methods wherein hybridizing oligomers are used to encrypt and transmit data, in diagnostic and screening assay methodologies, and as primers or building blocks for synthesizing larger polynucleotides.

Abstract: This invention relates to methods for making polynucleotides of any desired nucleotide sequence by repeating a series of reactions involving assembly of overlapping oligomers, ligation by DNA ligase, and cleavage with a restriction enzyme that cuts so as to add one or more additional nucleotides to a growing polynucleotide. This invention also relates to combining such a method for polynucleotide synthesis with a step employing localized melting of hybridized DNA oligomers, to synthesize an array of polynucleotides of different, defined nucleotide sequence on a substrate, and to the articles for polynucleotide hybridization so made.

Abstract: Disclosed is a method and apparatus for enhancing the brightness of both continuous and pulsed positron beams. By subjecting positrons to non-conservative forces in an interaction region, typically by means of a positron moderator such as a single crystal Cu(111)+S moderator, it is possible to circumvent the limitation, expressed in Liouville's theorem, of the optimally achievable brightness of a beam. The inventive method can be applied in successive stages involving accelerating and focusing a moderated positron beam, and moderating the energetic positrons to thermal energies, resulting typically in an increase in brightness by a factor of about 100 per stage, with an attendant reduction of flux by about factors of ten or less.

Abstract: A method for efficiently generating thermal positions from a source of energetic positrons, consisting of a method for increasing the emission efficiency of the positron source, and a method for increasing the efficiency of a positron moderator. In an advantageous case the combined improvements lead to an about ten-fold increase in generated thermal positrons. The method for improving the source efficiency consists in reducing the self-absorption of positrons, typically emitted from radioactive atoms incorporated into a substrate by means of diffusion, by the source. This is accomplished by providing for a backing layer having a relatively small diffusion constant for the radioactive species, and a thin diffusion layer having a relatively large such diffusion constant, with the diffusion layer deposited onto the backing layer.

Abstract: When subjected to radiation overload existing Geiger-Mueller counters may give an erroneously low reading, resulting in possible hazard to personnel. The instant invention discloses simple and inexpensive apparatus to remedy this dangerous shortcoming. Depending on the geometry of the detector tube, two possible failure modes have been identified, and circuitry is disclosed to detect the existence of these respective failure modes. The disclosed apparatus indicates the absence of an overload condition, in addition to signaling, by both visible and audible means, the existence of excessive radiation that might result in erroneously low reading of the Geiger-Mueller counter.