Showing papers by "University of Texas at Austin published in 1972"

Solution of the matrix equation AX + XB = C [F4]

Abstract: and Canada) or $18.00 (elsewhere). If the user sends a small tape (wt. less than 1 lb.) the algorithm will be copied on it and returned to him at a charge of $10.O0 (U.S. only). All orders are to be prepaid with checks payable to ACM Algorithms. The algorithm is re corded as one file of BCD 80 character card images at 556 B.P.I., even parity, on seven ~rack tape. We will supply the algorithm at a density of 800 B.P.I. if requested. The cards for the algorithm are sequenced starting at 10 and incremented by 10. The sequence number is right justified in colums 80. Although we will make every attempt to insure that the algorithm conforms to the description printed here, we cannot guarantee it, nor can we guarantee that the algorithm is correct.-L.D.F. Descdption The following programs are a collection of Fortran IV sub-routines to solve the matrix equation AX-.}-XB = C (1) where A, B, and C are real matrices of dimensions m X m, n X n, and m X n, respectively. Additional subroutines permit the efficient solution of the equation ArX + xa = C, (2) where C is symmetric. Equation (1) has applications to the direct solution of discrete Poisson equations [2]. It is well known that (1) has a unique solution if and only if the One proof of the result amounts to constructing the solution from complete systems of eigenvalues and eigenvectors of A and B, when they exist. This technique has been proposed as a computational method (e.g. see [1 ]); however, it is unstable when the eigensystem is ill conditioned. The method proposed here is based on the Schur reduction to triangular form by orthogonal similarity transformations. Equation (1) is solved as follows. The matrix A is reduced to lower real Schur form A' by an orthogonal similarity transformation U; that is A is reduced to the real, block lower triangular form.

Solid state electronic devices

Abstract: For undergraduate electrical engineering students or for practicing engineers and scientists interested in updating their understanding of modern electronics One of the most widely used introductory books on semiconductor materials, physics, devices and technology, Solid State Electronic Devices aims to: 1) develop basic semiconductor physics concepts, so students can better understand current and future devices; and 2) provide a sound understanding of current semiconductor devices and technology, so that their applications to electronic and optoelectronic circuits and systems can be appreciated. Students are brought to a level of understanding that will enable them to read much of the current literature on new devices and applications. Teaching and Learning Experience This program will provide a better teaching and learning experience-for you and your students. It will help: *Provide a Sound Understanding of Current Semiconductor Devices: With this background, students will be able to see how their applications to electronic and optoelectronic circuits and systems are meaningful. *Incorporate the Basics of Semiconductor Materials and Conduction Processes in Solids: Most of the commonly used semiconductor terms and concepts are introduced and related to a broad range of devices. *Develop Basic Semiconductor Physics Concepts: With this background, students will be better able to understand current and future devices.

The Socially Conscious Consumer

Abstract: Who are the socially conscious consumers? This article typologically classifies socially conscious consumers and evaluates the relative sensitivity of demographic and sociopsychological variables i...

Electrogenerated chemiluminescence. IX. Electrochemistry and emission from systems containing tris(2,2'-bipyridine)ruthenium(II) dichloride

Abstract: Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Electrogenerated chemiluminescence. IX. Electrochemistry and emission from systems containing tris(2,2'-bipyridine)ruthenium(II) dichloride Nurhan E. Tokel, and Allen J. Bard J. Am. Chem. Soc., 1972, 94 (8), 2862-2863• DOI: 10.1021/ja00763a056 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 19, 2009

Plasma Transport in Toroidal Confinement Systems

Abstract: The neoclassical theory of plasma transport in axisymmetric, toroidal confinement systems, is developed by means of a variational principle for the rate of irreversible entropy production. The variational principle derived here employs the full Fokker‐Planck collision operator, including both like and unlike species collisions. Using the variational principle, all the relevant neoclassical transport coefficients are systematically evaluated in the “banana” regime of small collisional frequency, to lowest order in the inverse aspect ratio. These results include both the “diagonal” and “cross” coefficients for the particle fluxes, ion and electron heat flux, and electric current. By combining the transport coefficients with appropriate moments of the drift equation, a closed set of equations which accurately summarize the predictions of neoclassical theory in the banana regime is obtained. The significance of these equations, in particular with regard to recent tokamak experiments, is discussed briefly.

Pollen Feeding and Reproductive Biology of Heliconius Butterflies

Abstract: Butterflies of the neotropical Genus Heliconius feed on pollen. This is the first known instance in butterflies of a habit that is well known for other insects. The butterflies remove amino acids and proteins from pollen; this feeding innovation plays a role in the reproductive and population biology of these insects. It is suggested that other animals may use pollen in a similar fashion.

The anatomy and function of a segment of the X chromosome of Drosophila melanogaster.

Abstract: An average size chromomere of the polytene X chromosome of Drosophila melanogaster contains enough DNA in each haploid equivalent strand to code for 30 genes, each 1,000 nucleotides long. We have attempted to learn about the organization of chromosomes by asking how many functional units can be localized within a chromomere. This was done by 1) recovery of mutants representative of every cistron in the 3A2-3C2 region; 2) the characterization of the function of each mutant type and grouping by complementation tests; 3) the determination of the genetic and cytological position of each cistron by recombination and deletion mapping. The data clearly show one functional group per chromomere. It is postulated that a chromomere is one cistron within which much of the DNA is regulatory in function.

Evolutionary genetics of cave-dwelling fishes of the genus astyanax.

Abstract: Attempts to understand evolutionary processes in cave organisms have been largely limited to speculation on the causes of loss of photoreceptor organs and pigmentation, increase in size and complexity of tactile sensory structures, and certain modifications in physiology (see review in Barr, 1968). Little is known of the population genetics of cave organisms or of the genetic changes accompanying the transformation of epigean (surface-dwelling) forms to troglobites (obligate cavernicoles). Yet genetic information is essential to the confident development of theories of troglobite evolution. For this reason, we have compared the genic character and degree of variability in troglobitic and epigean populations of the characid fish Astyanax mexicanus in Mexico. Students of cave biology have generally accepted the thesis that the ancestors of many troglobites entered caves as troglophiles (facultative cavernicoles) before the end of the Pleistocene, and became isolated with the local extinction of surface populations as a result of climatic changes associated with glaciation (Barr, 1968). If this is true, many troglobites have been living

Chebyshevian multistep methods for ordinary differential equations

Abstract: In this paper some theory of linear multistep methods fory (r) (x)=f(x,y) is extended to include smooth, stepsize-dependent coefficients. Treated in particular is the case where exact integration of a given set of functions is desired.

On the Flow-Shop Sequencing Problem with No Wait in Process†

Abstract: The optimization problem of minimizing the completion time in flow-shop sequencing with an environment of no intermediate storage is considered. Application of this problem in computer systems is pointed out and techniques are developed to solve the problem.

Optimal Scheduling Strategies in a Multiprocessor System

Abstract: This paper describes a set of techniques that can be used to optimally schedule a sequence of interrelated computational tasks on a multiprocessor computer system. Using a directed graph model to represent a computational process, two basic problems are solved here. First, given a set of computational tasks and the relationships between them, the tasks are scheduled such that the total execution time is minimized, and the minimum number of processors required to realize this schedule is obtained. The second problem is of a more general nature. Given k processors, the tasks are scheduled such that execution time is again minimized. Consideration is given to tasks of equal and unequal duration, and task preemption is not allowed.

Chemotherapy of sarcomas with a combination of adriamycin and dimethyl triazeno imidazole carboxamide

Abstract: During the initial therapeutic evaluations of adriamycin and DIC, efficacy was noted with each in the treatment of advanced sarcomas. Preclinical studies suggested possible synergism without additive toxicity. This lead to our evaluating the two agents in combination in metastatic sarcomas. Adriamycin at 60 mg/m2 was given I.V. on day 1 and DIC 250 mg/m2 I.V. on days 1 to 5, with the entire regimen repeated every 21 days. The dosage of both drugs was reduced 25% in patients with extensive prior therapy. Of 120 patients entered, 100 were evaluable for therapeutic efficacy. Five complete and 36 partial remissions (> 50%) were observed for a response rate of 41% including the following diagnoses: synovial cell sarcoma 2/2; rhabdomyosarcoma 3/5; undifferentiated sarcoma 6/13; fibrosarcoma 5/11; osteogenic sarcoma 8/18; liposarcoma 3/7; mesothelioma 3/7; neurofibrosarcoma 4/10; leiomyosarcoma 6/16; angiosarcoma 1/5; chondrosarcoma 0/4, and miscellaneous sarcomas 0/2. The median duration for complete remission was 5+ months (range—3+ to 7+ months) and for partial remission was 31/2+ months (1–10+ months) with 29/41 still in remission. Toxicity was limited predominantly to vomiting, alopecia, and myelosuppression. Leukocyte depression was maximum by median day 15, with prompt recovery permitting retreatment at a 3-week interval in all but 8% of courses. Combination therapy with adriamycin and DIC appears to be an effective and promising regimen in the treatment of metastatic sarcomas.

Toxicity of L-asparaginase in children with advanced leukemia

Abstract: A total of 105 patients with advanced acute leukemia in relapse received 123 trials of L-asparaginase. Three different schedules were used, two of which involved simultaneous administration of vincristine and prednisone. Treatment was temporarily interrupted because of toxicity in 14 patients, and permanently discontinued in an additional 31. In 13 patients, this occurred before 10 doses of L-asparaginase were given, while in the remaining 18 patients, therapy was stopped after remission was attained. The major toxicities were pancreatitis (fatal in four patients), hypersensitivity reactions, disturbances of liver function (fatal in two patients), and clinical and laboratory manifestations of central nervous system (CNS) dysfunction. Diabetic keto-acidosis was encountered in two patients and was fatal in one. Severe leukopenia ascribed to L-asparaginase occurred in two patients, in one of whom it was the contributory cause of death. Toxicity was not clearly different with any of the three treatment schedules. Most of the patients with only laboratory evidence of toxicity had no associated clinical manifestations, and this did not appear to decrease the likelihood of obtaining a remission.

Evidence for a Marking Pheromone Deterring Repeated Oviposition in Apple Maggot Flies

Abstract: Immediately following oviposition (but rarely following attempted boring without oviposition), apple maggot, Rhagoletis pomonella (Walsh), females were observed to circle around the fruit for about 30 seconds, dragging their fully-extended ovipositors on the fruit surface behind them. The results of field and laboratory experiments indicated that during such dragging, a pheromone deterring repeated boring is deposited on the fruit surface. Where the fruit was small (15-mm-diam cherries) and the drive to oviposit moderate (as among the field population), there was almost total deterrence for 4 days (i.e. until termination of the experiment) to any repeated boring in a fruit so marked by a single female. Where the fruit was large (55-mm-diam apples) or the drive to oviposit strong (as among laboratory flies deprived of oviposition sites), marking by only one female was insufficient to elicit strong deterrence. It is suggested that deposition of this marking pheromone is an important factor mediating uniformity in egg dispersion among available fruits, and that the amount of fruit surface area marked following a single oviposition is related to the amount of food or space required by one larva to grow to maturity. The potential utility of the pheromone in population suppression is also discussed.

Rollback and Recovery Strategies for Computer Programs

Abstract: Reliability is an important aspect of any system. On-line diagnosis, parity check coding, triple modular redundancy, and other methods have been used to improve the reliability of computing systems. In this paper another aspect of reliable computing systems is explored. The problem is that of recovering error-free information when an error is detected at some stage in the processing of a program. If an error or fault is detected while a program is being processed and if it cannot be corrected immediately, it may be necessary to run the entire program again. The time spent in rerunning the program may be substantial and in some real time applications critical. Recovery time can be reduced by saving states of the program (all the information stored in registers, primary and secondary storage, etc.) at intervals, as the processing continues. If an error is detected the program is restarted from its most recently saved state. However, a price is paid in saving a state in the form of time spent storing all the relevant information in secondary storage. Hence it is expensive to save the state of the program too often. Not saving any state of the program may cause an unacceptably large recovery time. The problem that we solve is the following. Determine the optimum points at which the state of the program should be stored to recover after any malfunction.

Electrogenerated chemiluminescence. VII. Influence of an external magnetic field on luminescence intensity

Abstract: The effect of an external magnetic field on the intensity of electrogenerated chemiluminescence (ecl) was determined for nine systems involving anthracene, 9,lO-diphenylanthracene (DPA), rubrene, 1,3,6,%tetraphenylpyrene (TPP), and fluoranthene as emitting species in N,N-dimethylformamide (DMF) solutions. Enhancements in emission intensity up to 27% with increasing field strength were noted for the energy-deficient oxidations of anthracene, DPA, rubrene, and TPP anion radicals by Wurster’s Blue cation, for the energy-deficient oxidation of fluoranthene anion radical by the cation radical of 10-methylphenothiazine, and for the energy-deficient reduction of the rubrene cation radical by the anion radical derived fromp-benzoquinone. No field effect was seen on luminescence arising from the apparently energy-sufficient mutual annihilation of the anion and cation radicals derived from DPA. The field enhanced luminescence from the reaction between the rubrene anion and cation radicals, but it exerted no effect on the intensity of emission from the TPP anion-cation radical annihilation. These results have been interpreted as reflecting a dual mechanism for chemiluminescent electron-transfer processes which divides on or about the line of energy sufficiency. In particular it is suggested that the field effect accompanying luminescence from energy-deficient systems arises from an inhibition by the field of the rate of quenching of emitter triplets by radical ions. Thus, the results are consistent with the triplet mechanism for luminescence from energydeficient systems. This interpretation also indicates that energy-sufficient systems yield luminescence without required triplet intermediates. For the two marginal systems involving rubrene and TPP alone, it is suggested that the rubrene anion-cation annihilation gives rise to luminescence predominantly via the triplet mechanism, while the TPP anion-cation reaction may be essentially energy sufficient, and that most luminescence from this process arises by direct population of the emitting state. arly in 1969, we first reported our observation E that an external magnetic field exerts unusual effects on the intensity of electrogenerated chemiluminescence (ecl) from two widely studied systems. Specifically, an enhancement of luminescence intensity was seen with increasing field strength for the light arising from the oxidations of the anthracene and 9,lOdiphenylanthracene (DPA) anion radicals by the Wurster’s Blue cation (the cation radical of N,N,N’ ,N’tetramethyl-p-phenylenediamine, WB) in N,N-dimethylformamide (DMF). In an interesting contrast, the intensity of light accompanying the mutual annihilation of DPA anion and cation radicals was unaffected (1) L. R. Faulkner and A. J. Bard. J. Amer. Chem. SOC., 91, 209 (1969). by the field. The two reactions involving the Wurster’s Blue cation as an oxidant are energy deficient in the sense that the energy contained in a single emitted photon is greater than the energy available from a single electron-transfer event. The third system is apparently energy sufficient. Thus, the contrast in the field effect on luminescence from these two kinds of systems was taken as evidence for long-suspected mechanistic differences between them. *-* Specifically, the results suggested that there exists at least one elementary reaction in the mechanism for luminescence from the energy-deficient systems whose rate is influenced by the (2) K. S. V. Santhanam and A. J. Bard, ibid., 87, 139 (1965). (3) A. Weller and K. Zachariasse, J. G e m . Phys., 46, 4984 (1967). (4) G. J. Hoytink, Discuss. Furaduy SOC., No. 45, 14 (1968).

Evidence for refractoriness of the pituitary‐gonadal axis to the pineal gland in golden hamsters and its possible implications in annual reproductive rhythms

Abstract: The testes of adult hamsters maintained in short daily photo-periods (light:dark “LD” cycles of 1:23, in hours) undergo regression within ten weeks and spontaneous regeneration within about 30 weeks. Thereafter (at least up to 80 weeks), as long as these animals are kept in short photoperiods the gonads do not experience a second atrophic response. After the 30 week period of dark exposure, if the hamsters are moved into a long photoperiodic environment (LD 14:10) for either one or ten weeks and are then returned to short photoperiods, the gonads do not involute a second time. However, if the duration of exposure to LD 14:10 is increased to 22 weeks, the return to LD 1:23 causes the gonads to degenerate. The regressive responses of the testes never occur in hamsters that have been pinealectomized indicating that the observed changes are mediated by this gland. The inability of darkness and, thus the pineal gland, to induce a second gonadal involution unless the hamsters are maintained in LD cycles of 14:10 for 22 weeks (after a 30 week period of dark exposure) may be explicable in terms of (1), a transient refractoriness of the brain to the pineal antigonadotropic principle or (2), the temporary failure of the pineal to be activated by short daily photoperiods.

Exact and approximate solutions to the multisource weber problem

Abstract: The problem considered is the choice of locations form sources so as to minimize the sum of weighted distances betweenn fixed sinks and the source closest to each sink. The weights represent the amounts to be shipped between the sinks and their respective sources; the allowable source locations are free of restriction. An algorithm for the approximate solution of the problem, and computational experience with it, are discussed first. A branch-and-bound algorithm for exact solution of the problem is then developed, and computational experience with it is described.

Infections in cancer patients. Results with gentamicin sulfate therapy.

Abstract: Gentamicin was administered to 101 cancer patients during 122 episodes of infection. Sixty-two (51%) infections responded. The drug was most effective for the treatment of urinary tract infection and cellulitis and ineffective against infections involving multiple body sites. Most of the infections were caused by Serratia marcescens, Pseudomonas aeruginosa, and Klebsiella sp. The response to gentamicin therapy was related to the patients' neutrophil counts. Only five of the 23 (22%) infections occurring in patients with less than 100 neutrophils per mm3 responded favorably, whereas 29 of the 51 (57%) infections occurring in patients with more than 1000 neutrophils per mm3 responded favorably. Fourteen (11%) superinfections occurred while patients were receiving gentamicin. Nephrotoxicity occurred in 30% of patients with normal renal function at the onset of gentamicin therapy.

Reducibility of the Families of 0-Dimensional Schemes on a Variety.

Abstract: IfA is a regular local ring of dimensionr>2, over an algebraically closed fieldk, we show that the Hilbert scheme Hilb n A parametrizing ideals of colengthn inA(dim k A/I=n) has dimension>cn 2−2/r and is reducible, for alln>c′, wherec andc′ depend only onr. We conclude that ifV is a nonsingular projective variety of dimensionr>2, the Hilbert scheme Hilb n V parametrizing the 0-dimensional subschemes ofV having lengthn, is reducible for alln>c″(r). We may takec″(r) to be (1) $$102 ifr = 3,25 ifr = 4,35 ifr = 5,and\left( {1 + r} \right)\left( {{{1 + r} \mathord{\left/ {\vphantom {{1 + r} 4}} \right. \kern- ulldelimiterspace} 4}} \right)ifr > 5.$$ The result answers in the negative a conjecture of Fogarty [1] but leaves open the question of the conjectured irreducibility of Hilb n A, whereA has dimension 2. Hilb n V is known to be irreducible ifV is a nonsingular surface (Hartshorne forP 2, and Fogarty [1]). In all cases Hilb n V and Hilb n A are known to be connected (Hartshorne forP r, and Fogarty [1]). The author is indebted to Hartshorne for suggesting that Hilb n A might be reducible ifr>2. The proof has 3 steps. We first show that ifV is a variety of dimensionr, then Hilb n V is irreducible only if it has dimensionr n. We then show that ifA is a regular local ring of dimensionr, Hilb n A can be irreducible only if it has dimension (r−1)(n−1). Finally in § 3 we construct a family of graded ideals of colengthn in the local ringA, and having dimensionc′ n2−2/r. Since for largen this dimension is greater thanr n, and since Hilb n A↪Hilb n V whenA is the local ring of a closed point onV, the proof is complete, except for (1), which follows from § 3, and the monotonicity of (dim Hilb n V−r n) (see (2)). In § 4, we comment on some related questions.