Showing papers by "University of Naples Federico II published in 1993"

Modulation of adjuvant arthritis by endogenous nitric oxide

Abstract: 1. The role of endogenous nitric oxide (NO) in adjuvant arthritis in Lewis rats has been studied by use of L-arginine, the amino acid from which NO is synthesized, and NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Prolonged modulation (35 days) of the L-arginine: NO pathway in rats was achieved by dissolving test compounds in the drinking water (L-arginine: 3, 10 and 30 mg ml-1; L-NAME: 0.1, 1 and 10 mg ml-1). 2. Arthritis was exacerbated by L-arginine and suppressed by L-NAME in a dose-related fashion. Combined treatment with L-NAME (1 mg ml-1) and L-arginine (30 mg ml-1) did not modify the arthritis. 3. Reduced weight gain, which is a feature of adjuvant arthritis, was modified by these compounds so that L-arginine reduced weight gain whereas L-NAME increased weight gain compared with that in control animals. 4. D-Arginine (30 mg ml-1), NG-nitro-D-arginine methyl ester (D-NAME: 1 mg ml-1) and L-lysine (30 mg ml-1), an amino acid not involved in the generation of NO, were without effect on either arthritis or body weight gain. 5. Antigen-stimulated proliferation of T-lymphocytes as well as generation of nitrite (NO2-) and release of acid phosphatase from macrophages were all enhanced in L-arginine-treated arthritic rats and reduced in L-NAME-treated animals. 6. These results suggest that endogenous NO modulates adjuvant arthritis, possibly by interfering with the activation of T-lymphocytes and/or macrophages.

The parallel approach to force/position control of robotic manipulators

Abstract: Force/position control strategies provide an effective framework to deal with tasks involving interaction with the environment. In this paper the parallel approach to force/position control of robotic manipulators is presented. It shows a complete use of the available sensor measurements by operating the control action in a full-dimensional space without using selection matrices. Conflicting situations between the position and force tasks are managed using a priority strategy: the force control loop is designed to prevail over the position control loop. This choice ensures limited deviations from the prescribed force trajectory in every situation, guaranteeing automatic recovery from unplanned collisions. A dynamic force/position parallel control law is presented and its performance in presence of an elastic environment is analyzed; simplification of the dynamic control law is also discussed leading to a PID-type parallel controller. Two case studies are worked out that show the effectiveness of the approach in application to an industrial robot. >

Cardiac Effects of Long Term Thyrotropin-Suppressive Therapy with Levothyroxine*

Abstract: To investigate the effects of long term thyroid hormone suppressive therapy on the heart, 20 patients were evaluated by noninvasive techniques. Of them, 10 were athyreotic after surgery for differentiated thyroid cancer, and 10 had diffuse or nodular goiter. The mean age of the group was 39 +/- 11 yr. Twenty age- and sex-matched subjects served as controls. The mean dose of levothyroxine was 163 +/- 34 micrograms daily. Plasma TSH was undetectable in all patients. Mean serum T4, free T4, and sex hormone-binding globulin were significantly higher (P < 0.001), whereas mean serum T3, free T3, and osteocalcin did not differ from control levels. Cardiac evaluation consisted of a standard 12-lead electrocardiogram, an ambulatory electrocardiographic monitoring (Holter), and an echocardiographic study. Two patients showed abnormal electrocardiograms for left ventricular hypertrophy. Holter demonstrated an increase in average heart rate (84 +/- 7 vs. 70 +/- 6 beats/min; P < 0.01). Prevalence of atrial premature b...

Analysis of Convection and Secondary Reaction Effects Within Porous Solid Fuels Undergoing Pyrolysis

Abstract: A mathematical model of transport phenomena (heat, momentum and mass transfer) and chemical processes (primary and secondary reactions) of the thermal degradation of wood is presented. Implicit finite difference equations for energy, momentum and chemical species mass balances are formulated according to an operator-splitting technique and are numerically solved. The progress of the pyrolysis process along a wooden slab, radiatively heated on one side, is characterized by the following main processes: 1( a virgin wood region, crossed by a slow flow of pyrolysis products, where temperature and pressure values decrease as the non-irradiated boundary is approached; 2( a primary pyrolysis region where, due to the relatively low temperatures, secondary reactions are not active and 3( a char layer where volatile products of primary pyrolysis mainly flow and, temperature being higher, undergo secondary reactions. For low medium permeabilities, a peak in the gas overpressure is observed, separating the v...

Water Transport in Organic Coatings

Abstract: The electrochemical impedance spectroscopy (EIS) technique was used to evaluate the water transport (diffusion and equilibrium water uptake) and the dielectric properties of freestanding polyimide (Kapton® and PMDA-ODA) and polyethyleneterephthalate (PET) membranes at 25 and 40°C, respectively, and in supported PMDA-ODA-coated metals. Permeability and diffusion coefficients of freestanding films were also obtained by using the Payne cup method and the MacBain quartz spring balance in order to assess the reliability of the EIS method when compared to other techniques. Results from this work show that the diffusivity of water in polyimide films varies from 1.42 × 10−9 to 3.53 × 10−9 cm2 s−1 for thickness between 2.4 and 125 μm, while the equilibrium water uptake varies from 2.31 to 4.63% by weight for the same range of thickness. The average calculated dielectric constant of the freestanding Kapton® films is 4.5. Water diffusion coefficient in PET varies from 2.11 × 10−9 to 12.61 × 10−9 cm2 s−1 for...

Effect of coenzyme Q10 therapy in patients with congestive heart failure: a long-term multicenter randomized study.

Abstract: The improved cardiac function in patients with congestive heart failure treated with coenzyme Q10 supports the hypothesis that this condition is characterized by mitochondrial dysfunction and energy starvation, so that it may be ameliorated by coenzyme Q10 supplementation. However, the main clinical problems in patients with congestive heart failure are the frequent need of hospitalization and the high incidence of life-threatening arrhythmias, pulmonary edema, and other serious complications. Thus, we studied the influence of coenzyme Q10 long-term treatment on these events in patients with chronic congestive heart failure (New York Heart Association functional class III and IV) receiving conventional treatment for heart failure. They were randomly assigned to receive either placebo (n = 322, mean age 67 years, range 30–88 years) or coenzyme Q10 (n = 319, mean age 67 years, range 26–89 years) at the dosage of 2 mg/kg per day in a 1-year double-blind trial. The number of patients who required hospitalization for worsening heart failure was smaller in the coenzyme Q10 treated group (n = 73) than in the control group (n = 118, P < 0.001). Similarly, the episodes of pulmonary edema or cardiac asthma were reduced in the control group (20 versus 51 and 97 versus 198, respectively; both P < 0.001) as compared to the placebo group. Our results demonstrate that the addition of coenzyme Q10 to conventional therapy significantly reduces hospitalization for worsening of heart failure and the incidence of serious complications in patients with chronic congestive heart failure.

Daily Vitamin E Supplements Improve Metabolic Control But Not Insulin Secretion in Elderly Type II Diabetic Patients

Abstract: OBJECTIVE To investigate the potential metabolic benefits deriving from daily vitamin E administration in type II diabetic patients. RESEARCH DESIGN AND METHODS Twenty-five type II diabetic patients were invited to randomly take placebo or vitamin E (d-α-tocopherol; 900 mg/day) along a similar 3-mo period in a double-blind, crossover procedure. A wash-out period of 30 days separated the two treatment periods. At the end of each treatment period blood samples were drawn for plasma metabolites determination, and an intravenous glucose tolerance test (25 g of glucose as bolus in 3 min) was performed. During this study oral hypoglycemic agents were not discontinued or changed in their dosage. RESULTS Chronic vitamin E administration reduced plasma glucose (8.3 ± 0.3 vs. 7.5 ± 0.2 mM, P > 0.05), triglycerides (2.27 ± 0.08 vs. 1.67 ± 0.09 mM, P P P 1 levels (7.8 ± 0.3 vs. 7.1 ± 0.5%, P CONCLUSIONS Daily vitamin E supplements seem to produce a minimal but significant improvement in the metabolic control in type II diabetic patients. More studies are necessary before conclusions can be drawn about the safety of vitamin E during long-term administration.

Abnormally high thromboxane biosynthesis in homozygous homocystinuria. Evidence for platelet involvement and probucol-sensitive mechanism.

Abstract: Homocystinuria due to homozygous cystathionine beta-synthase deficiency is an inborn error of metabolism characterized by a high incidence of thrombosis and premature atherosclerosis. We evaluated TXA2 biosynthesis in vivo and several in vitro tests of platelet function in 11 homocystinuric patients and 12 healthy controls. In vitro, patients' platelet aggregation was within control values as were TXB2 formation, fibrinogen binding, and ATP secretion in response to thrombin. In contrast, the urinary excretion of 11-dehydro-TXB2, a major enzymatic derivative of TXA2, was > 2 SD of controls in all patients (1,724 +/- 828 pg/mg creatinine, mean +/- SD, in patients vs. 345 +/- 136 in controls, P 80%. The recovery of 11-dehydro-TXB2 excretion over the 10 d that followed aspirin cessation occurred with a pattern consistent with the entry into the circulation of platelets with intact cyclooxygenase activity. Prolonged partial reduction in the abnormally high excretion of both 11-dehydro-TXB2 and 2,3-dinor-TXB2, was also observed in seven patients who ingested 500 mg daily for 3 wk of the antioxidant drug probucol. These results provide evidence for enhanced thromboxane biosynthesis in homocystinuria and for its partial dependence on probucol-sensitive mechanisms. Furthermore, the elevated TXA2 formation in homocystinuria is likely to reflect, at least in part, in vivo platelet activation.

Antimicrobial activity of a newly identified bacteriocin of Bacillus cereus

Abstract: A bacteriocin-producing Bacillus cereus strain was isolated. The bacteriocin, here called cerein, was shown to be active specifically against other B. cereus strains and inactive against all other bacterial species tested. Cerein was detected in the culture supernatants of stationary-phase cells, and its appearance was inhibited by induction of sporulation. The bacterial activity of cerein was insensitive to organic solvents and nonproteolytic enzymes, partially stable to heat, and active over a wide range of pH values. Direct detection of antimicrobial activity on sodium dodecyl sulfate-polyacrylamide gel suggested an apparent molecular mass of about 9 kDa.

Suicide risk in Huntington's disease.

Abstract: In order to evaluate the relevance of suicide risk in families affected by Huntington's disease (HD), 2793 subjects registered with the National Huntington's Disease Research Roster were studied. Suicide was the reported cause of death in 205 subjects (7.3%). This group included affected and possibly affected subjects, subjects at 50% and 25% risk, possibly at risk subjects, and normal relatives. In all categories suicide was more frequent than in the general US population. The data suggest that suicide is quite frequent in some families with HD. This increased suicide risk must be carefully considered in planning genetic counselling for predictive testing in HD.

Temporal Lobe Epilepsy in Early Childhood

Abstract: To explore the electroclinical features of temporal lobe epilepsy (TLE) in early childhood, we studied results of video-EEG and other tests of 14 children aged 16 months to 12 years selected by seizure-free outcome after temporal lobectomy. Four children had mesiotemporal sclerosis, 1 had cortical dysplasia, and 9 had low-grade temporal neoplasms. The children had complex partial seizures (CPS) with symptomatology similar to that of adults with TLE, including decreased responsiveness and automatisms. Automatisms tended to be simpler in the younger children, typically limited to lip smacking and fumbling hand gestures. Scalp/sphenoidal EEG showed anterior/inferior temporal interictal sharp waves and unilateral temporal seizure onset in the 4 children with mesiotemporal sclerosis and in the child with cortical dysplasia, but EEG findings in 9 children with low-grade temporal tumors were complex, including multifocal interictal sharp waves or poorly localized or falsely lateralized EEG seizure onset. In children without tumors, video-EEG was critical to localization of the epileptogenic zone for resection, but in patients with tumors video-EEG was less localizing and its main value was to confirm that the reported behaviors were epileptic seizures with semiology typical of temporal lobe onset.

Limb body wall complex: a critical review and a nosological proposal.

Abstract: The analysis of the literature on limb body wall complex reveals a varied and rather confused spectrum of cases. However, we noticed the presence of at least 2 clearly distinguishable phenotypes. The first phenotype shows craniofacial defects and amniotic bands and/or adhesion; the second--without craniofacial defects--presents urogenital anomalies, anal atresia, and abdominal placental attachment, together with a persistence of the extra-embryonic coelom. We think these 2 phenotypes are the consequence of different pathogenetic mechanisms. The pathogenesis of the first type can be related to an early vascular disruption, while the pathogenesis of the second one is attributable to an intrinsic embryonal maldevelopment. Eight cases of the second phenotype were identified and the pathological findings proving this maldevelopmental origin are described.

First supermodule of the MACRO detector at Gran Sasso

Abstract: In this paper the design, construction and performance of the lower part of the first supermodule of the MACRO detector is described.

Evidence for biventricular involvement in acromegaly: a Doppler echocardiographic study

Abstract: To investigate left and right ventricular involvement in acromegaly, 20 patients were studied by Doppler echocardiography. Nine of them had systemic hypertension. Right ventricular free wall thickness was significantly increased in acromegalic patients (8 +/- 2 vs 4 +/- 1 mm; P < 0.001). Left ventricular mass index was augmented both in the whole group and in the subgroup of normotensive acromegalics, as compared with normals (134 +/- 33 and 115 +/- 20 vs 80 +/- 18 g.m-2; P < 0.01). Ejection phase indices were normal in the patient group, while impaired left and right ventricular diastolic filling was found. In fact isovolumic relaxation time was prolonged (118 +/- 21 vs 78 +/- 12 ms; P < 0.001), ratio of early to late mitral (0.9 +/- 0.3 vs 1.8 +/- 0.5; P < 0.001) and tricuspid (1.0 +/- 0.2 vs 1.4 +/- 0.3; P < 0.001) flow velocities were significantly decreased as compared with controls. Superior vena cava flowmetry was also abnormal showing a marked decrease of diastolic filling wave and, consequently, of the ratio between peak diastolic and peak systolic flow velocity. No significant differences were observed between normotensive and hypertensive acromegalics, except for left ventricular mass index (115 +/- 20 vs 156 +/- 31 g.m-2; P < 0.01). These findings indicate that abnormal diastolic filling patterns of transmitral, transtricuspid, and superior vena cava flowmetry suggesting 'impaired relaxation' associated with increased left and right ventricular mass, frequently occur in acromegaly.

Release of cytokines induced by Salmonella typhimurium porins.

Abstract: Salmonella typhimurium SH5014 porins induce the release of tumor necrosis factor alpha (TNF-alpha), interleukin 1 alpha (IL-1 alpha), and IL-6 by human monocytes and of gamma interferon (IFN-gamma) and IL-4 by human lymphocytes. Porins at 1 microgram/ml induce the greatest release of TNF-alpha, IL-1 alpha, and IL-6 by monocytes and of IL-4 by lymphocytes, while porins at 5 micrograms/ml induce the greatest release of IFN-gamma by lymphocytes. The R form of lipopolysaccharide (LPS-R) induces the greatest release of TNF-alpha and IL-1 alpha by monocytes when used at a low concentration (1 microgram/ml). At higher concentrations (5 and 10 micrograms/ml, respectively), LPS-R induces the maximal release of IL-6 from monocytes and the maximal release of IL-4 from lymphocytes. The S form of LPS (LPS-S) induces the greatest release of TNF-alpha, IL-1 alpha, and IL-6 by monocytes and that of IL-4 by lymphocytes when used at a concentration of 1 microgram/ml. After stimulation with LPS-S, the largest quantity of TNF-alpha and IL-1 alpha released was less than that obtained after stimulation with LPS-R at the same concentration, while the quantity of IL-6 released was found to be slightly higher than that obtained after stimulation with porins or LPS-R. LPS-S (1 microgram/ml) induces IFN-gamma release from lymphocytes in notably smaller quantities than that obtained with LPS-R and slightly larger quantities than that obtained with porins. The preparation of porins used was found to be contaminated with 10 pg of LPS per 10 micrograms of porins, a quantity which was found to have no biological effect; furthermore, porin preparations with the addition of polymyxin B gave the same results.

Inhibitors of nitric oxide synthetase prevent castor-oil-induced diarrhoea in the rat

Abstract: 1. Castor oil (2 ml orally) produced copious diarrhoea in rats 3 h after its administration. 2. Pretreatment (intraperitoneal, i.p.) of rats with the NO synthesis inhibitors NG-nitro-L-arginine methyl ester (L-NAME, 1-25 mg kg-1) and NG-monomethyl-L-arginine (L-NMMA, 2.5-100 mg kg-1) inhibited or prevented castor-oil-induced diarrhoea. L-Arginine (150-600 mg kg-1, i.p.) administered to rats pretreated with L-NAME 10 mg kg-1, drastically reduced the antidiarrhoeal activity of L-NAME in a dose-related manner. D-Arginine (900 mg kg-1) did not modify the protection by L-NAME. 3. Pretreatment (i.p.) of rats with L-NAME (2.5-25 mg kg-1) decreased the intestinal fluid accumulation and Na+ secretion induced by castor oil. L-Arginine (600 mg kg-1) but not D-arginine (900 mg kg-1) counteracted the inhibitory effect of L-NAME (10 mg kg-1). 4. L-NAME (10 and 25 mg kg-1) had no significant effect on the intestinal transit in normal rats or those given castor oil. 5. These results provide evidence that nitric oxide (NO) could play an important role in castor-oil-induced diarrhoea.

Human Urokinase Receptor Concentration in Malignant and Benign Breast Tumors by in Vitro Quantitative Autoradiography: Comparison with Urokinase Levels

Abstract: We measured the tissue concentration of human urokinase receptor (uPAR) in 22 breast carcinomas and 9 benign breast lesions using in vitro quantitative autoradiography. Tissue sections were incubated with increasing concentrations of 125I-pro-urokinase in the presence or absence of unlabeled competitor. Breast carcinomas were found to contain 5 times more uPAR than benign breast lesions with respect to their protein content [523 +/- 72 versus 108 +/- 20 (SE) fmol/mg (P < 0.001)]. Simultaneous quantitation of urokinase (uPA) by immunoenzymatic assay on tissue extracts from the same specimens showed that breast carcinomas also contain 19 times more uPA than benign tumors (611 +/- 134 versus 32 +/- 8 fmol/mg) (P < 0.01). The reliability of quantitative autoradiography measurements was confirmed by uPAR cross-linking assay on membrane fraction from either U937 histiocytic lymphoma cells or breast carcinomas and immunoperoxidase staining with an anti-uPAR antibody on tumor sections. Also, immunoperoxidase staining with an anti-uPA monoclonal antibody showed that uPA is indeed localized on the plasma membrane of epithelial tumor cells in confined areas of breast carcinomas whereas cells from benign breast lesions were devoid of uPA under the same experimental conditions. In conclusion, our findings support the hypothesis that uPAR plays a central role in the acquisition of an invasive phenotye and favor its potential use as a prognostic factor in patients with breast carcinoma.

c-fos mRNA is spontaneously induced in the rat brain during the activity period of the circadian cycle

Abstract: The basal expression of the proto-oncogene c-fos was studied by Northern blot analysis in different regions of the rat brain during 24 h. A striking spontaneous oscillation of c-fos mRNA expression was detected in animals kept in basal conditions with a 12 h light/12 h dark cycle. In these animals c-fos mRNA was just detectable during the rest hours (morning through afternoon), and was high during the activity hours (night). The periodicity of this oscillation persisted and became free-running when the animals were exposed for 6 consecutive days to constant light or darkness. It was thus demonstrated that the fluctuation of c-fos expression is circadian and is not created by the light-dark cycle, but the latter exerts a synchronizing effect. The oscillation of c-fos mRNA was modified by manipulations of the rest-activity cycle. In particular, the fluctuation observed in basal conditions was inverted, keeping the animals awake during the rest hours (diurnal) and allowing them to sleep in the activity period (nocturnal). These data indicated a close relationship between the oscillation of c-fos expression and the rest-activity cycle. Finally, electroencephalographic (EEG) monitoring was performed under behavioural control for 3 h before the animals were killed. These experiments confirmed that, irrespective of the time of day, the EEG pattern typical of a state of sleep (including both slow waves and paradoxical sleep) was associated with low or undetectable c-fos levels, whereas the protracted EEG desynchronization corresponding to wakefulness was associated with high c-fos expression.(ABSTRACT TRUNCATED AT 250 WORDS)

A neural network approach for identification and fault diagnosis on dynamic systems

Abstract: The possibilities offered by neural networks for overcoming both system identification and fault diagnosis problems in dynamic systems are investigated. In particular, an original neural fault diagnosis procedure is illustrated. Its sensitivity and response time enables it to be used to great advantage in online applications. Some applications are also reported which, although pertaining to a simple linear dynamic system, highlight the general applicability and advantages of a neural approach. >

Omeprazole and high dose ranitidine in the treatment of refractory reflux oesophagitis.

Abstract: Thirty two consecutive patients (age range 6 months-13.4 years) with severe reflux oesophagitis were randomised to a therapeutic trial for eight weeks during which they received either standard doses of omeprazole (40 mg/day/1.73 m2 surface area) or high doses of ranitidine (20 mg/kg/day). Twenty five patients completed the trial (12 on omeprazole, 13 on ranitidine). At entry and at the end of the trial patients underwent symptomatic score assessment, endoscopic and histological evaluation of the oesophagus, and simultaneous oesophageal and gastric pH measurement; results are given as median (range). Both therapeutic regimens were effective in decreasing clinical score (omeprazole before 24.0 (15-33), after 9.0 (0-18); ranitidine before 19.5 (12-33), after 9.0 (6-12)), in improving the histological degree of oesophagitis (omeprazole before 8.0 (6-10), after 2.0 (0-60); ranitidine before 8.0 (8-10), after 2.0 (2-6), and in reducing oesophageal acid exposure, measured as minutes of reflux at 24 hour pH monitoring (omeprazole before 129.4 (84-217), after 44.6 (0.16-128); ranitidine before 207.3 (66-306), after 58.4 (32-128)) as well as intragastric acidity, measured as median intragastric pH (omeprazole before 2.1 (1.0-3.0), after 5.1 (2.2-7.4); ranitidine before 1.9 (1.6-4), after 3.4 (2.3-5.3)). Serum gastrin concentration was > 150 ng/l in four patients on omeprazole and in three patients on ranitidine. It is concluded that in children with refractory reflux oesophagitis high doses of ranitidine are comparable with omeprazole for the healing of oesophagitis and relief of symptoms; both drugs resulted in efficacious reduction of intragastric acidity and intra-oesophageal acid exposure.

Inversion-Based Nonlinear Control of Robot Arms with Flexible Links

Abstract: The design of inversion-bas ed nonlinear control laws solving the problem of accurate trajectory tracking for robot arms having flexible links is considered. It is shown that smooth joint trajectories can always be exactly reproduced preserving internal stability of the closed-loop system. The interaction between the Lagrangian/assumed modes modeling approach and the complexity of the resulting inversion control laws is stressed. The adoption of clamped boundary conditions at the actuation side of the flexible links allows considerable simplification with respect to the case of pinned boundary conditions. The resulting control is composed of a nonlinear state feedback compensation term and of a linear feedback stabilization term. A feedforward strategy for the nonlinear part is also investigated. Simulation results are presented for a planar manipulator with two flexible links, displaying the performance of the proposed controllers also in terms of end-effector behavior.

Production of somatic hybrids between frost-tolerant Solanum commersonii and S. tuberosum: characterization of hybrid plants.

Abstract: Somatic fusion of mesophyll protoplasts was used to produce hybrids between the frost-tolerant species Solanum commersonii (2n=2x=24) and dihaploid S. tuberosum (2n=2x=24). This is a sexually incompatible combination due to the difference in EBN (Endosperm Balance Number, Johnston et al. 1980). Species with different EBNs as a rule are sexually incompatible. Fifty-seven hybrids were analysed for variation in chromosome number, morphological traits, fertility and frost tolerance. About 70% of the hybrids were tetraploid, and 30% hexaploid. Chloroplast counts in stomatal guard cells revealed a low frequency of cytochimeras. The frequency of aneuploids was relatively higher at the hexaploid level (hypohexaploids) than at the tetraploid level (hypotetraploids). The somatic hybrids were much more vigorous than the parents, and showed an intermediate phenotype for several morphological traits and moderate to profuse flowering. Hexaploid hybrid clones were less vigorous and had a lower degree of flowering than the tetraploid hybrid clones. All of the hybrids were female fertile but male sterile except for one, which was fully fertile and self-compatible. Many seeds were produced on the latter clone by selfing and on the male-sterile clones by crossing. The somatic hybrid plants showed an introgression of genes for frost tolerance and an adaptability to cold from S. commersonii. Therefore, the use of these somatic hybrids in breeding for and in genetic esearch on frost tolerance and cold-hardening is suggested.

Pitch-synchronous wavelet representations of speech and music signals

Abstract: A new wavelet representation is explored. The transform is based on a pitch-synchronous vector representation and it adapts to the oscillatory or aperiodic characteristics of signals. Pseudo-periodic signals are represented in terms of an asymptotically periodic trend and aperiodic fluctuations at several scales. The transform reverts to the ordinary wavelet transform over totally aperiodic signal segments. The pitch-synchronous wavelet transform is particularly suitable to the analysis, rate-reduction coding and synthesis of speech signals and it may serve as a preprocessing block in automatic speech recognition systems. Feature extraction such as separation of voice from noise in voiced consonants is easily performed by means of partial wavelet expansions. A stochastic model of aperiodic fluctuations is proposed. >