Showing papers by "University of Utah published in 1979"

Suppression of acoustic noise in speech using spectral subtraction

Abstract: A stand-alone noise suppression algorithm is presented for reducing the spectral effects of acoustically added noise in speech. Effective performance of digital speech processors operating in practical environments may require suppression of noise from the digital wave-form. Spectral subtraction offers a computationally efficient, processor-independent approach to effective digital speech analysis. The method, requiring about the same computation as high-speed convolution, suppresses stationary noise from speech by subtracting the spectral noise bias calculated during nonspeech activity. Secondary procedures are then applied to attenuate the residual noise left after subtraction. Since the algorithm resynthesizes a speech waveform, it can be used as a pre-processor to narrow-band voice communications systems, speech recognition systems, or speaker authentication systems.

Simultaneous hermaphroditism and sexual selection.

Abstract: Theory about the evolution of sexual behavior in dioecious species is based on the general assumption that egg production is limited by a female's ability to garner resources to make eggs, not by a lack of sperm to fertilize them. Reproductive success for males is thus limited by access to females (and their eggs). I suggest that egg production by simultaneous hermaphrodites also obeys this principle-that fertilized egg production by an individual is not limited by sperm availability, but by resources allocated to eggs. If true, this suggests that sperm competition (reproduction success through male function) and a form of male-female conflict have played important roles in the evolution of hermaphroditism.

Pollen dispersal and optimal outcrossing in Delphinium nelsoni

Abstract: NATURAL SELECTION, in sexually reproducing plants, should often favour matings between individuals of intermediate genetic similarity. Matings between very similar individuals may lead to inbreeding depression because segregational load is revealed1,2, while matings between very dissimilar individuals may disrupt favourable gene combinations and lead to outbreeding depression3–5. Outbreeding depression in plants has been documented in crosses between species, varieties and isolated populations6–9, and reports of inbreeding depression date back at least a century10 We suggest that outbreeding depression will often occur on a much finer scale than previously recognised, especially in plants subject to restricted pollen and seed dispersal. Such plants are likely to show pronounced microgeographic genetic differentiation resulting from drift in subpopulations isolated by distance or from adaptation to local edaphic and biotic conditions11,12 Under these circumstances, a short outcrossing distance may be optimal not only because of intragenotypic effects, but also because it produces offspring sufficiently similar to the female parent to grow successfully near her, yet sufficiently genotypically diverse to maximise success of the total progeny in the face of coarse-grained temporal environmental variation13–15, frequency-dependent sibling competition16–18 or predation19–20. Here we present evidence that a short outcrossing distance is optimal for Delphinium nelsoni Greene and discuss the relationship between the optimal outcrossing distance for D. nelsoni and actual pollen dispersal by its main pollinators.

Hfr formation directed by tn10.

Abstract: The transposable drug-resistance element, Tn10, can serve as a region of homology to direct the insertion of an F'ts114 lac plasmid into the chromosome of Salmonella typhimurium. Derivatives of F'ts114 lac were constructed that carry Tn10 insertions; these plasmids were transferred to strains having a Tn10 insertion in the chromosome. Under these circumstances, Hfr formation requires homologous recombination between plasmid-borne and chromosomal Tn10 elements. The process is dependent on recA function and on the presence of both Tn10 elements. All Hfr's isolated from a given merodiploid show the same direction of transfer. Depending on the orientation of Tn10 in the F' plasmid, Hfr's transferring in either direction can be obtained from any chromosomal Tn10 insertion. Since Tn10 insertions can be generated in any region of the chromosome, this method permits the isolation of Hfr's with either direction of transfer having their origin at almost any predetermined site. The Hfr's constructed by this method are sufficiently stable for standard genetic mapping crosses, and they have also been used to generate new F' plasmids. Implicit in the results above is the possibility of determining the orientation of any chromosomal Tn10 insertion by constructing an Hfr using a standard F' Tn10 plasmid and determining the direction of chromosome transfer. The general approaches described here are applicable to other transposable elements and other bacterial systems.

Reaction mechanism for the acid ferric sulfate leaching of chalcopyrite

Abstract: The acid ferric sulfate leaching of chalcopyrite, CuFeS2 + 4Fe+3 = Cu+2 + 5Fe+2 + 2S0 was studied using monosize particles in a well stirred reactor at ambient pressure and dilute solid phase concentration in order to obtain fundamental details of the reaction kinetics. The principal rate limiting step for this electrochemical reaction appears to be a transport process through the elemental sulfur reaction product. This conclusion has been reached in other investigations and is supported by data from this investigation in which the reaction rate was found to have an inverse second order dependence on the initial particle diameter. Furthermore, the reaction kinetics were found to be independent of Fe+3, Fe+2, Cu+2 and H2SO4 in the range of additions studied. The unique aspect of this particular research effort is that data analysis, using the Wagner theory of oxidation, suggests that the rate limiting process may be the transport of electrons through the elemental sulfur layer. Predicted reaction rates calculated from first principles using the physicochemical properties of the system (conductivity of elemental sulfur and the free energy change for the reaction) agree satisfactorily with experimentally determined rates. Further evidence which supports this analysis includes an experimental activation energy of 20 kcal/mol (83.7 kJ/mol) which is approximately the same as the apparent activation energy for the transfer of electrons through elemental sulfur, 23 kcal/ mol (96.3 kJ/mol) calculated from both conductivity and electron mobility measurements reported in the literature.

A spectral subtraction algorithm for suppression of acoustic noise in speech

Abstract: Spectral subtraction has been shown to be an effective approach for reducing ambient acoustic noise in order to improve the intelligibility and quality of digitally compressed speech. This paper presents a set of implementation specifications to improve algorithm performance and minimize algorithm computation and memory requirements. It is shown spectral subtraction can be implemented in terms of a nonstationary, multiplicative, frequency domain filter which changes with the time varying spectral characteristics of the speech. Using this filter a speech activity detector is defined and used to allow the algorithm to adapt automatically to changing ambient noise environments. Also the bandwidth information of this filter is used to further reduce the residual narrowband noise components which remain after spectral subtraction.

Afferent influences on the development of the brain stem auditory nuclei of the chicken: Otocyst ablation

Abstract: The effects of embryonic deafferentation on the morphological development of the avian cochlear nuclei, n. angularis (NA) and n. magnocellularis (NM), were investigated. The right otocyst was surgically removed from chick embryos at 55 to 60 hours of incubation and the subsequent development of total volume, neuron number, and neuron cross-sectional area were studied with quantitative methods in animals sacrificed at 2-day intervals between embryonic days 9 and 19 and at 28 days posthatching. The development of NA and NM is severely affected by otocyst ablation. Between embryonic days 9 and 19, a large group of NA neurons in the medioventral portion of the nucleus on the perated side moves to an ectopic ventromedial position, while the remainder of this nucleus stays in its normal dorsolateral position. Beginning about day 13 of incubation, the normal increase in the volume of NA and the size of its neurons becomes progressively retarded and 40% of its neurons are lost. The growth of NM is also retarded after day 11 of incubation and the growth of mean neuron size is retarded after day 15. There is a 30% loss of neurons in NM which begins after embronic day 11. The results indecate the primary cochlear fibers make a critical contribution to the growth and maintenance of their target neurons. The absence of this facilitative influence following otocyst ablation becomes apparent just at the time synapses would normally be formed between the promary auditory afferents and the brain stem auditory neurons. The abnormal movement of neurons in nucleus angularis to an ectopic position after otocyst ablation suggests that primary auditory afferents may serve to stabilize the position of their target cells within the developing brain.

Characterization of Molybdena Catalysts

Abstract: Publisher Summary The term molybdena is used in this chapter to denote a composite catalyst consisting of molybdenum oxide supported on an activated support, commonly alumina. Early it was found that certain transition metals, notably cobalt and nickel, promote the molybdena catalyst for hydrodesulfurization (HDS) reactions. The chapter discusses the various characterization techniques, which have been applied to this catalyst system. The chapter aims to relate what each technique reveals about the nature of the catalyst, and to present an overall picture of the state of the catalyst as it now appears. The chapter mentions some selective catalyst activity tests that were designed to give some fundamental insights into the catalyst state or active sites present. The chapter provides a comparison of their properties to the catalyst systems to assess to what degree they may be present in the catalyst.

An Investigation of Situational Variation in Brand Choice Behavior and Attitude

Abstract: Empirical evidence is presented which supports the explicit consideration of situational factors in the study of consumer behavior. Situational variation of brand choice behavior and attitude is id...

Fentanyl-oxygen anaesthesia for coronary artery surgery: cardiovascular and antidiuretic hormone responses.

Abstract: This study demonstrates that large doses of fentanyl, as the sole anaesthetic with ventilation with oxygen, produces complete anaesthesia and minimal changes in cardiovasuclar dynamics in patients with coronary artery disease. It also indicates that high dose fentanyl anaesthesia blocks the increase in plasma anti-diuretic hormone and cardiovascular dynamics which are so common with morphine and other anaesthetic techniques during tracheal intubation and surgical stimulation in patients with coronary artery disease. Our findings suggest that fentanyl-oxygen anaesthesia is an attractive technique in patients with coronary artery disease.

Palatal myoclonus and denervation supersensitivity in the central nervous system

Abstract: We postulate that palatal myoclonus after infarction of the brainstem or cerebellum, or both, is the manifestation of denervation supersensitivity secondary to lesions involving the dentatorubroolivary system. Two cases of our own and 31 from the English and French literature were analyzed in order to determine the delay between the occurrence of presumed anatomical lesions and the recognition of palatal myoclonus. The intervals varied from 2 to 49 months with the median between 10 and 11 months. The natural history of palatal myoclonus following brainstem infarction seemed consistent with the hypothesis.

Influence of dopamine synthesis on methamphetamine-induced changes in striatal and adrenal tyrosine hydroxylase activity.

Abstract: Methamphetamine in large doses decreases striatal tyrosine hydroxylase activity. This effect is prevented by neuroleptic agents such as chlorpromazine and haloperidol which would suggest that released dopamine may be involved in the response. To test this hypothesis, we have altered dopamine synthesis with α-methyl-p-tyrosine and l-Dopa and found that dopamine synthesis is necessary for the observed depression of striatal TH activity by methamphetamine. In the adrenal gland, however, the increase in TH activity by methamphetamine is not prevented by inhibition of catecholamine synthesis. It is possible that released dopamine may be inhibiting TH activity by activation of pre- or postsynaptic dopamine receptors in the neostriatum resulting in activation of the neuronal feedback pathway or released dopamine may act on dendrodendritic autoreceptors in the substantia nigra.

The effect of dichloromethylene diphosphonate, a pyrophosphate analog, on bone and bone cell structure in the growing rat.

Abstract: Dichloromethylene diphosphonate (Cl2MDP) is a synthetic compound related in structure to inorganic pyrophosphate but is resistant to enzymatic and chemical degradation and is known to be a potent inhibitor of bone resorption. The administration of 20 mg/kg/day of Cl2MDP for ten days to growing rats results in marked increases in metaphyseal mineralized tissue mass due to slowed bone resorption. There was an increase in resorption areas covering anorganic bone viewed by scanning electron microscopy (SEM), however, the resorption pits, or Howship's lacunae, in these resorption areas were smaller and less defined than those encountered in controls. The appearance of these large areas of poorly delineated resorption pits is likely due to an inhibition of bone resorption coupled with slowed bone formation. Administration of Cl2MDP to growing rats also results in an increase in the numbers and size of osteoclasts. Because this would appear to be a histological paradox, in view of the ability of Cl2MDP to slow bone resorption, the osteoclasts were examined by transmission electron microscopy (TEM). The ruffled borders and associated cytoplasmic vacuoles were generally less extensive in the Cl2MDP-treated osteoclasts than in controls, even though clear zones were frequently seen. Examination of undecalcified light microscope sections reveal that the area of bone being degraded by adjacent osteoclasts was generally much smaller in the Cl2MDP-treated animals than in controls. Thus the collaborating TEM observations of smaller ruffled borders, with the SEM observations of smaller, less-de-fined resorption pits, with the light microscope observations of smaller bone areas being degraded by individual osteoclasts provide a morphological basis for the observed decreases in bone resorption following Cl2MDP administration.

Breast Cancer Risk Factors Among Screening Program Participants

Abstract: Data were obtained by mailed questionnaire from 405 breast cancer patients identified during the first 2 years of operation of the Breast Cancer detection Demonstration Project in the U.S. and from a sample of 1156 normal screenees (response rate = 88%) in an attempt to examine whetHer the usual risk indicators for breast cancer apply to individuals participating in screening programs. No substantial differences were found between the respondents and the nonrespondents for the variables on which information had been obtained at the time of the initial screening. Nearly all of t(e recognized risk factors were seen in this population. The relative risk (FF) of breast cancer was 3.9 among women whose mothers were also affected; this finding was statistically significant. Relative risk was increased for women reporting early menarche late menopause nulliparity late age when 1st child was born and excessive weight. The relative risk was not elevated in women with a prior breast biopsy but was excessive for those with more than 1 biopsy. No association with thyroid medications or menopausal hormones was found. Among women having undergone a natural menopause a nonstatistically significant elevation in the relative risk was noted for long term oral contraceptive users; this excess relative risk was restricted to those using OCs in the presence of breast cancer risk indicators. The results indicate the need for further study of women with extended periods of OC use particularly when accompanied by other known risk indicators.

Clinically practical lead systems for improved electrocardiography: comparison with precordial grids and conventional lead systems.

Abstract: The use of limited leads for estimating total body surface potential distributions was investigated as a practical solution to the problem associated with extensive electrocardiographic sampling used in surface potential mapping. Two practical, limited lead sets of 32 leads each were derived and contrasted to a set of 30 precordial leads similar to those used in ST-segment and QRS mapping for estimating infarct size, and to a set of nine leads simulating those used in conventional 12-lead examinations. The two arrays, one of which excluded posterior sites for use in recumbent patients, showed little difference in ability to estimate 192 lead measured maps (average rms voltage error of 35 muV and average correlation coefficient of 0.97). The 30- and 9-lead arrays consistently showed twice the voltage (72 muV) and poorer pattern estimation (average correlation coefficient of 0.91) than either of the 32 lead arrays. These findings indicate the need for 20-35 properly located electrodes for accurate total body surface potential estimation. They also show that there is no difference in the abilities of a 30-lead precordial array and conventional leads to estimate maps.

Research on Teacher Education

Abstract: It should be noted at the outset that there is both little general acceptance of the need for educational research and little appreciation of the relevance of such research for the improvement of education. A tradition of research does not exist in education as it does, for example, in medicine or in engineering, where both professionals and consumers commonly agree that research and progress are almost synonymous. (p. 6)

Studies on the evolution of elastin--I. Phylogenetic distribution.

Abstract: 1. Aortae and other tissues from numerous animals were examined for the presence of the rubbery protein elastin by (a) chemical purification and amino acid analysis, (b) presence of the cross-linking amino acids desmosine and isodesmosine and (c) histological staining. 2. Elastin was found in all vertebrates examined (42 species) with the exception of cyclostomes (3 species). It was absent from all invertebrates tested (14 species). 3. The amino acid compositions of vertebrate elastins showed marked and interesting interspecies variations.

Air-sparged hydrocyclone and method

Abstract: An air-sparged hydrocyclone apparatus and method, the apparatus including a substantially hollow, cyclone body having a cylindrical section and a downwardly oriented conical section. An inlet, an overflow and an underflow are also provided in the cyclone body. At least a portion of the wall of the cyclone body is modified to include an air-sparging section wherein air, under pressure, is forced into the interior of the cyclone body as a plurality of bubbles. The bubbles disrupt the boundary layer, freeing entrapped fine particles and also assist in carrying hydrophobic particles to the overflow. The introduction of discrete, small, air bubbles is enhanced by forming a portion of the wall of the cyclone body from a porous material.

Hartree-Fock density of states for extended systems

Abstract: The density of states (DOS) of extended systems, calculated at the rigorous Hartree-Fock (HF) level, can have a number of unphysical features. It is shown analytically that in partially filled band systems (crystals, thin films, polymers) the HF DOS vanishes at the Fermi energy, regardless of Fermi-surface shape. HF DOS will also vanish, in the (rare) event that an equienergetic surface $S$ for an energy different from the Fermi energy coincides with the Fermi surface ${S}_{F}$. Additional features such as shoulders, peaks, or near gaps can occur at energies with surfaces $S$ close to ${S}_{F}$. No HF-related zero DOS arises in filled-band extended systems. Published HF DOS are discussed. A detailed summary of expressions for crystal HF matrix elements in momentum representation is given. Their modification for thin films and polymers is indicated.