Analysis of nonlinear dynamics of vocal folds using high-speed video observation and biomechanical modeling

Primary voice production occurs in the larynx through vibrational movements carried out by vocal folds. However, many problems can affect this complex system resulting in voice disorders. In this context, time-frequency-shape analysis based on embedding phase space plots and nonlinear dynamics methods have been used to evaluate the vocal fold dynamics during phonation. For this purpose, the present work used high-speed video to record the vocal fold movements of three subjects and extract the glottal area time series using an image segmentation algorithm. This signal is used for an optimization method which combines genetic algorithms and a quasi-Newton method to optimize the parameters of a biomechanical model of vocal folds based on lumped elements (masses, springs and dampers). After optimization, this model is capable of simulating the dynamics of recorded vocal folds and their glottal pulse. Bifurcation diagrams and phase space analysis were used to evaluate the behavior of this deterministic system in different circumstances. The results showed that this methodology can be used to extract some physiological parameters of vocal folds and reproduce some complex behaviors of these structures contributing to the scientific and clinical evaluation of voice production. (C) 2010 Elsevier Inc. All rights reserved.

Comparison between frequency domain and time domain riser analysis

In the optimization or parametric analyses of risers, several configurations must be analyzed. It is laborious to perform time domain solutions for the dynamic analysis, since they are time-consuming tasks. So, frequency domain solutions appear to be a possible alternative, mainly in the early stages of a riser design. However, frequency domain analysis is linear and requires that nonlinear effects are treated. The aim of this paper is to present a possible way to treat some of these nonlinearities, using an iterative process together with an analytical correction, and compare the results of a frequency domain analysis with the those of a full nonlinear analysis. [DOI: 10.1115/1.4006149]

Assessment of micronucleus frequency in the peripheral blood of female rats in persistent estrus treated with selective estrogen receptor modulators

The aim of this study was to evaluate micronucleus (MN) frequency in polychromatic erythrocytes (PCE) of female rats in persistent estrus (a model developed to mimic polycystic ovary syndrome) treated with selective estrogen receptor modulators (SERMs, tamoxifen, and raloxifene). Forty female Wistar-Hannover rats were divided into four groups of 10 animals each: Group I (normally cycling rats) and Group II (persistent estrus) both received only vehicle, while Group III (persistent estrus) was treated with tamoxifen (250 mu g/animal/day) and Group IV (persistent estrus) was treated with raloxifene (750 mu g/animal/day). Tamoxifen and raloxifene were given by oral gavage beginning on postnatal day 90 and continuing for 30 consecutive days. Peripheral blood samples were collected from tails 1 day following the last exposure. Blood smears were made on glass slides and stained with 10% Giemsa solution. ANOVA and a Tukey post-hoc test were used for data analysis. Mean percentages of MN were 1.82 +/- 0.13, 5.20 +/- 0.24, 3.32 +/- 0.13, and 3.04 +/- 0.12 in Groups I, II, III, and IV, respectively. The results indicate that tamoxifen and raloxifene similarly reduced the formation of MNPCE of female rats in persistent estrus (P < 0.0001 for Groups III and IV vs. Group II), using the dosages and time periods applied in the present study. The data suggest possibly antimutagenic effects of SERMs under high levels of estrogens. The findings also suggest that this is an interesting animal model for studying the genotoxicity of estrogens. Environ. Mol. Mutagen. 2012. (C) 2011 Wiley Periodicals, Inc.

Frequency of subtype B and F1 dual infection in HIV-1 positive, Brazilian men who have sex with men

Background: Because various HIV vaccination studies are in progress, it is important to understand how often inter- and intra-subtype co/superinfection occurs in different HIV-infected high-risk groups. This knowledge would aid in the development of future prevention programs. In this cross-sectional study, we report the frequency of subtype B and F1 co-infection in a clinical group of 41 recently HIV-1 infected men who have sex with men (MSM) in Sao Paulo, Brazil. Methodology: Proviral HIV-1 DNA was isolated from subject's peripheral blood polymorphonuclear leukocytes that were obtained at the time of enrollment. Each subject was known to be infected with a subtype B virus as determined in a previous study. A small fragment of the integrase gene (nucleotide 4255-4478 of HXB2) was amplified by nested polymerase chain reaction (PCR) using subclade F1 specific primers. The PCR results were further confirmed by phylogenetic analysis. Viral load (VL) data were extrapolated from the medical records of each patient. Results: For the 41 samples from MSM who were recently infected with subtype B virus, it was possible to detect subclade F1 proviral DNA in five patients, which represents a co-infection rate of 12.2%. In subjects with dual infection, the median VL was 5.3 x 10(4) copies/ML, whereas in MSM that were infected with only subtype B virus the median VL was 3.8 x 10(4) copies/ML (p > 0.8). Conclusions: This study indicated that subtype B and F1 co-infection occurs frequently within the HIV-positive MSM population as suggested by large number of BF1 recombinant viruses reported in Brazil. This finding will help us track the epidemic and provide support for the development of immunization strategies against the HIV.

Spectral Induced Polarization (SIP) signatures of clayey soils containing toluene

We performed laboratory experiments to investigate the sensitivity of the Spectral Induced Polarization (SIP) method to toluene contamination in clayey soils. We used mixtures of quartzitic sand and montmorillonite as soil samples, artificially contaminated with varying amounts of toluene. Care was taken to quantify the experimental uncertainty resulting from packing since such effects must be quantified if variations in SIP signatures between samples are to be reliably interpreted in terms of the effects of hydrocarbon concentration. The SIP response of all samples following addition of toluene was monitored for a period of 40 days following sample preparation. Stepwise regression was used to examine the statistical significance of correlations between (i) clay content and (ii) toluene concentration and SIP parameters. Both single-frequency real and imaginary conductivity measurements, along with the integral chargeability, normalized chargeability, DC conductivity and time constant obtained from a Debye decomposition fitting, were examined in this regression analysis. The SIP measurements show a clear time dependence following sample preparation, indicating that samples containing toluene may take significant time to reach an equilibrium electrical response. SIP measurements are significantly related to toluene content shortly after sample preparation, when the expected dependence of SIP on clay concentration is apparently suppressed. However, for the state of electrical equilibrium after 40 days (interpreted to indicate surface chemistry at equilibrium) there is no significant relation between SIP measurements and toluene content; instead SIP measurements are then significantly correlated with clay concentration. The total chargeability, normalized chargeability and relaxation time obtained from the Debye decomposition show no correlation with toluene content, indicating that this procedure, which likely integrates over multiple mechanisms, may not be suitable for understanding relationships between SIP and hydrocarbon contamination. We find only small low-frequency polarization signals observed in relation to toluene concentration (2 mrad at 0.01 Hz), which initially decreases the interfacial polarization. Unlike earlier works, our results do not support the use of the SIP method as a tool for monitoring toluene contamination in clay soils.

Frequency upconversion properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles

Frequency upconversion (UC) properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles (NPs) were investigated. Infrared-to-visible and infrared-to-infrared UC processes associated to the Tm3+ ions were studied by exciting the samples with a cw 1050 nm ytterbium laser. The luminescence intensity as a function of laser intensity was also measured using a pulsed 1047 nm Nd3+:YVO laser in order to determine the number of photons participating in the UC processes. Enhancement of the UC signals for samples heat-treated during various time intervals is attributed to the growth of the local field in the vicinity of the NPs. PL enhancement by one-order of magnitude was observed in the whole spectrum of the samples heat-treated during 48 h. On the other hand PL quenching was observed for the samples heat-treated more than 48 h. (c) 2011 Elsevier B.V. All rights reserved.

ANALYSIS OF THE NATURAL VIBRATION FREQUENCY TEST METHOD TO OBTAIN THE MODULUS OF ELASTICITY OF WOOD STRUCTURAL COMPONENTS

There are several techniques to characterize the elastic modulus of wood and those currently using the natural frequencies of vibration stand out as they are non-destructive techniques, producing results that can be repeated and compared over time. This study reports on the effectiveness of the testing methods based on the natural frequencies of vibration versus static bending to obtain the elastic properties of reforested structural wood components usually employed in civil construction. The following components were evaluated: 24 beams of Eucalyptus sp. with nominal dimensions (40 x 60 x 2.000 mm) and 14 beams of Pinus oocarpa with nominal dimensions (45 x 90 x 2.300 mm) both without treatment; 30 boards with nominal dimensions (40 x 240 x 2.010 mm) and 30 boards with nominal dimensions (40 x 240 x 3.050 mm), both of Pinus oocarpa and with chromate copper arsenate (CCA) preservative treatment. The results obtained in thiswork show good correlation when compared to the results obtained by the static bending mechanical method, especially when applying the natural frequency of longitudinal vibration. The use of longitudinal frequency was reliable and practical, therefore recommended for determining the modulus of elasticity of wood structural elements. It was also found that no specific support is needed for the specimens using the longitudinal frequency, as well as no previous calibrations, reducing the execution time and enabling to test many samples.

LONG TIME CORRELATIONS OF NONLINEAR LUTTINGER LIQUIDS

An overview is given of the limitations of Luttinger liquid theory in describing the real time equilibrium dynamics of critical one-dimensional systems with nonlinear dispersion relation. After exposing the singularities of perturbation theory in band curvature effects that break the Lorentz invariance of the Tomonaga-Luttinger model, the origin of high frequency oscillations in the long time behaviour of correlation functions is discussed. The notion that correlations decay exponentially at finite temperature is challenged by the effects of diffusion in the density-density correlation due to umklapp scattering in lattice models.

The influence of tourniquet use and operative time on the incidence of deep vein thrombosis in total knee arthroplasty

OBJECTIVE: To evaluate the association between tourniquet and total operative time during total knee arthroplasty and the occurrence of deep vein thrombosis. METHODS: Seventy-eight consecutive patients from our institution underwent cemented total knee arthroplasty for degenerative knee disorders. The pneumatic tourniquet time and total operative time were recorded in minutes. Four categories were established for total tourniquet time: <60, 61 to 90, 91 to 120, and >120 minutes. Three categories were defined for operative time: <120, 121 to 150, and >150 minutes. Between 7 and 12 days after surgery, the patients underwent ascending venography to evaluate the presence of distal or proximal deep vein thrombosis. We evaluated the association between the tourniquet time and total operative time and the occurrence of deep vein thrombosis after total knee arthroplasty. RESULTS: In total, 33 cases (42.3%) were positive for deep vein thrombosis; 13 (16.7%) cases involved the proximal type. We found no statistically significant difference in tourniquet time or operative time between patients with or without deep vein thrombosis. We did observe a higher frequency of proximal deep vein thrombosis in patients who underwent surgery lasting longer than 120 minutes. The mean total operative time was also higher in patients with proximal deep vein thrombosis. The tourniquet time did not significantly differ in these patients. CONCLUSION: We concluded that surgery lasting longer than 120 minutes increases the risk of proximal deep vein thrombosis.

Dynamic symmetry loss of high-frequency hysteresis loops in single-domain particles with uniaxial anisotropy

Understanding how magnetic materials respond to rapidly varying magnetic fields, as in dynamic hysteresis loops, constitutes a complex and physically interesting problem. But in order to accomplish a thorough investigation, one must necessarily consider the effects of thermal fluctuations. Albeit being present in all real systems, these are seldom included in numerical studies. The notable exceptions are the Ising systems, which have been extensively studied in the past, but describe only one of the many mechanisms of magnetization reversal known to occur. In this paper we employ the Stochastic Landau-Lifshitz formalism to study high-frequency hysteresis loops of single-domain particles with uniaxial anisotropy at an arbitrary temperature. We show that in certain conditions the magnetic response may become predominantly out-of-phase and the loops may undergo a dynamic symmetry loss. This is found to be a direct consequence of the competing responses due to the thermal fluctuations and the gyroscopic motion of the magnetization. We have also found the magnetic behavior to be exceedingly sensitive to temperature variations, not only within the superparamagnetic-ferromagnetic transition range usually considered, but specially at even lower temperatures, where the bulk of interesting phenomena is seen to take place. (C) 2011 Elsevier B.V. All rights reserved.

Frequency and predictors of symptomatic intracranial hemorrhage after intravenous thrombolysis for acute ischemic stroke in a Brazilian public hospital

OBJECTIVE: Scarce data are available on the occurrence of symptomatic intracranial hemorrhage related to intravenous thrombolysis for acute stroke in South America. We aimed to address the frequency and clinical predictors of symptomatic intracranial hemorrhage after stroke thrombolysis at our tertiary emergency unit in Brazil. METHOD: We reviewed the clinical and radiological data of 117 consecutive acute ischemic stroke patients treated with intravenous thrombolysis in our hospital between May 2001 and April 2010. We compared our results with those of the Safe Implementation of Thrombolysis in Stroke registry. Univariate and multiple regression analyses were performed to identify factors associated with symptomatic intracranial transformation. RESULTS: In total, 113 cases from the initial sample were analyzed. The median National Institutes of Health Stroke Scale score was 16 (interquartile range: 10-20). The median onset-to-treatment time was 188 minutes (interquartile range: 155-227). There were seven symptomatic intracranial hemorrhages (6.2%; Safe Implementation of Thrombolysis in Stroke registry: 4.9%; p = 0.505). In the univariate analysis, current statin treatment and elevated National Institute of Health Stroke Scale scores were related to symptomatic intracranial hemorrhage. After the multivariate analysis, current statin treatment was the only factor independently associated with symptomatic intracranial hemorrhage. CONCLUSIONS: In this series of Brazilian patients with severe strokes treated with intravenous thrombolysis in a public university hospital at a late treatment window, we found no increase in the rate of symptomatic intracranial hemorrhage. Additional studies are necessary to clarify the possible association between statins and the risk of symptomatic intracranial hemorrhage after stroke thrombolysis.

Millennial-scale climate cycles in Permian-Carboniferous rhythmites: Permanent feature throughout geologic time?

Two late Paleozoic glacial rhythmite successions from the Itarare Group (Parana Basin, Brazil) were examined for paleoclimate variations. Paleomagnetic (characteristic remanent magnetization, ChRM) and magnetic susceptibility (K(z)) measurements taken from the rhythmites are interpreted as paleoclimatic proxies. Ratios of low-frequency components in the K(z) variations suggest Milankovitch periodicities; this leads to recognition of other, millennial-scale variations reminiscent of abrupt climate changes during late Quaternary time, and are suggestive of Bond cycles and the 2.4 k.y. solar cycle. We infer from these patterns that millennial-scale climate change is not restricted to the Quaternary Period, and that millennial forcing mechanisms may have been prevalent throughout geologic time.

Frequency of LCT -13910C>T single nucleotide polymorphism associated with adult-type hypolactasia/lactase persistence among Brazilians of different ethnic groups

Abstract Background Adult-type hypolactasia, the physiological decline of lactase some time after weaning, was previously associated with the LCT -13910C>T polymorphism worldwide except in Africa. Lactase non-persistence is the most common phenotype in humans, except in northwestern Europe with its long history of pastoralism and milking. We had previously shown association of LCT -13910C>T polymorphism with adult-type hypolactasia in Brazilians; thus, we assessed its frequency among different Brazilian ethnic groups. Methods We investigated the ethnicity-related frequency of this polymorphism in 567 Brazilians [mean age, 42.1 ± 16.8 years; 157 (27.7%) men]; 399 (70.4%) White, 50 (8.8%) Black, 65 (11.5%) Brown, and 53 (9.3%) Japanese-Brazilian. DNA was extracted from leukocytes; LCT -13910C>T polymorphism was analyzed by PCR-restriction fragment length polymorphism. Results Prevalence of the CC genotype associated with hypolactasia was similar (57%) among White and Brown groups; however, prevalence was higher among Blacks (80%) and those of Japanese descent (100%). Only 2 (4%) Blacks had TT genotype, and 8 (16%) had the CT genotype. Assuming an association between CC genotype and hypolactasia, and CT and TT genotypes with lactase persistence, 356 (62.8%) individuals had hypolactasia and 211 (37.2%) had lactase persistence. The White and Brown groups had the same hypolactasia prevalence (~57%); nevertheless, was 80% among Black individuals and 100% among Japanese-Brazilians (P < 0.01). Conclusion The lactase persistence allele, LCT -13910T, was found in about 43% of both White and Brown and 20% of the Black Brazilians, but was absent among all Japanese Brazilians studied.

HTLV-1/2 seroprevalence and coinfection rate in Brazilian first-time blood donors: an 11-year follow-up

The seroprevalence and geographic distribution of HTLV-1/2 among blood donors are extremely important to transfusion services. We evaluated the seroprevalence of HTLV-1/2 infection among first-time blood donor candidates in Ribeirão Preto city and region. From January 2000 to December 2010, 1,038,489 blood donations were obtained and 301,470 were first-time blood donations. All samples were screened with serological tests for HTLV-1/2 using enzyme immunoassay (EIA). In addition, the frequency of coinfection with hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), Chagas disease (CD) and syphilis was also determined. In-house PCR was used as confirmatory test for HTLV-1/2. A total of 296 (0.1%) first-time donors were serologically reactive for HTLV-1/2. Confirmatory PCR of 63 samples showed that 28 were HTLV-1 positive, 13 HTLV-2 positive, 19 negative and three indeterminate. Regarding HTLV coinfection rates, the most prevalent was with HBV (51.3%) and HCV (35.9%), but coinfection with HIV, CD and syphilis was also detected. The real number of HTLV-infected individual and coinfection rate in the population is underestimated and epidemiological studies like ours are very informative.

Time lags of the kilohertz quasi-periodic oscillations in the low-mass X-ray binaries 4U 1608−52 and 4U 1636−53

We studied the energy and frequency dependence of the Fourier time lags and intrinsic coherence of the kilohertz quasi-periodic oscillations (kHz QPOs) in the neutron-star lowmass X-ray binaries 4U 1608−52 and 4U 1636−53, using a large data set obtained with the Rossi X-ray Timing Explorer. We confirmed that, in both sources, the time lags of the lower kHz QPO are soft and their magnitude increases with energy. We also found that: (i) In 4U 1636−53, the soft lags of the lower kHz QPO remain constant at∼30 μs in the QPO frequency range 500–850 Hz, and decrease to ∼10 μs when the QPO frequency increases further. In 4U 1608−52, the soft lags of the lower kHz QPO remain constant at 40 μs up to 800 Hz, the highest frequency reached by this QPO in our data. (ii) In both sources, the time lags of the upper kHz QPO are hard, independent of energy or frequency and inconsistent with the soft lags of the lower kHz QPO. (iii) In both sources the intrinsic coherence of the lower kHz QPO remains constant at ∼0.6 between 5 and 12 keV, and drops to zero above that energy. The intrinsic coherence of the upper kHz QPO is consistent with being zero across the full energy range. (iv) In 4U 1636−53, the intrinsic coherence of the lower kHz QPO increases from ∼0 at ∼600 Hz to ∼1, and it decreases to ∼0.5 at 920 Hz; in 4U 1608−52, the intrinsic coherence is consistent with the same trend. (v) In both sources the intrinsic coherence of the upper kHz QPO is consistent with zero over the full frequency range of the QPO, except in 4U 1636−53 between 700 and 900 Hz where the intrinsic coherence marginally increases. We discuss our results in the context of scenarios in which the soft lags are either due to reflection off the accretion disc or up-/down-scattering in a hot medium close to the neutron star. We finally explore the connection between, on one hand the time lags and the intrinsic coherence of the kHz QPOs, and on the other the QPOs’ amplitude and quality factor in these two sources.