Fast Band Research Articles

The impact of the microphone position on the frequency analysis of snoring sounds

Frequency analysis of snoring sounds has been reported as a diagnostic tool to differentiate between different sources of snoring. Several studies have been published presenting diverging results of the frequency analyses of snoring sounds. Depending on the position of the used microphones, the results of the frequency analysis of snoring sounds vary. The present study investigated the influence of different microphone positions on the outcome of the frequency analysis of snoring sounds. Nocturnal snoring was recorded simultaneously at six positions (air-coupled: 30 cm middle, 100 cm middle, 30 cm lateral to both sides of the patients' head; body contact: neck and parasternal) in five patients. The used microphones had a flat frequency response and a similar frequency range (10/40 Hz-18 kHz). Frequency analysis was performed by fast Fourier transformation and frequency bands as well as peak intensities (Peaks 1-5) were detected. Air-coupled microphones presented a wider frequency range (60 Hz-10 kHz) compared to contact microphones. The contact microphone at cervical position presented a cut off at frequencies above 300 Hz, whereas the contact microphone at parasternal position revealed a cut off above 100 Hz. On an exemplary base, the study demonstrates that frequencies above 1,000 Hz do appear in complex snoring patterns, and it is emphasised that high frequencies are imported for the interpretation of snoring sounds with respect to the identification of the source of snoring. Contact microphones might be used in screening devices, but for a natural analysis of snoring sounds the use of air-coupled microphones is indispensable.

Alzheimer disease versus mixed dementias: An EEG perspective

Objective To examine differences between patients with AD ( n = 54) and mixed (vascular Alzheimer) dementia ( n = 24), and controls ( n = 66), with respect to clinic, neuropsychology, neuroradiology and quantitative EEG (QEEG). Methods We used CAMDEX, CT and QEEG. Results Patients with mixed dementia had more subcortical lesions. Increased slow frequency EEG power was observed in mixed dementia compared to AD, whereas the level of high frequency power was nearly normal in mixed dementia, but decreased in pure AD. Topography of slow band power was unaltered in both groups, but was changed for fast bands. The Hachinski score and neuropsychological tests showed small differences between mixed dementia and pure AD. Conclusion Neuroimaging and QEEG made a greater differential diagnostic contribution than clinical symptoms and neuropsychology. An alteration of slow frequency power with nearly normal high frequency power in mixed dementia may reflect subcortical pathology, whereas cortical pathology in pure AD may relate to decreased fast frequency power. With vascular pathology, less AD pathology is needed for a similar severity of dementia. Significance In dementia of the Alzheimer type a vascular component is often found – especially at an older age. The quantitative EEG can contribute to a better understanding of the interaction of the two components.

On the origin of the fast photoluminescence band in small silicon nanoparticles

Colloidal suspensions of small silicon nanoparticles (diameter around 2 nm) with fast and efficient ultraviolet–blue photoluminescence (PL) band are fabricated by enhanced electrochemical etching of Si wafers. The detailed study of photoluminescence excitation spectra in a wide range of excitation photon energies (270–420 nm) reveals specific behavior of the Stokes shift of the fast PL band that agrees well with theoretical calculation of optical transitions in small silicon nanocrystals and is distinct from emission of silicon dioxide defects.

Changes in slow and fast alpha bands in subjects submitted to different amounts of functional electrostimulation

To examine the changes in slow (8-10Hz) and fast (10-12Hz) alpha bands of EEG in three groups of subjects submitted to different amounts of functional electrostimulation (FES). Our hypothesis is that different amounts of electrostimulation may cause different patterns of activation in the sensorimotor cortex. In particular, we expect to see an increase in alpha power due to habituation effects. We examine the two bands comprised by alpha rhythm (i.e., slow and fast alpha), since these two sub-rhythms are related to distinct aspects: general energy demands and specific motor aspects, respectively. The sample was composed of 27 students, both sexes, aging between 25 and 40 years old. The subjects were randomly distributed in three groups: control (n=9), G24 (n=9) and G36 (n=9). A FES equipment (Neuro Compact-2462) was used to stimulate the right index finger extension. Simultaneously, the electroencephalographic signal was acquired. We investigated the absolute power in slow and fast alpha bands in the sensorimotor cortex. The G36 indicated a significant increasing in absolute power values in lower and higher alpha components, respectively, when compared with the control group. Particularly, in the following regions: pre-motor cortex and primary motor cortex. FES seems to promote cortical adaptations that are similar to those observed when someone learns a procedural task. FES application in the G36 was more effective in promoting such neural changes. The lower and higher components of alpha rhythms behave differently in their topographical distribution during FES application. These results suggest a somatotopic organization in primary motor cortex which can be represented by the fast alpha component.

Time-resolved cathodoluminescence and photoluminescence of nanoscale oxides

The nanostructured oxide materials such as ZnO, ZrO 2, and Y 3Al 5O 12 (YAG) are perspective materials for transparent scintillating and/or laser ceramics. The luminescence properties of single crystals, nanopowders and ceramic were compared. Nominally pure and rare-earth doped nanopowders and ceramics have been studied by means of time-resolved luminescence spectroscopy. The fast blue luminescence band was studied in ZnO ceramics sintering from different raw materials. The luminescence centres of ZrO 2:Y were compared in a single crystal, ceramic and nanopowder. It is shown that ceramic sintering parameters have a strong influence on time-resolved luminescence characteristics in cerium-doped YAG.

EEG spectral power and sleepiness during 24 h of sustained wakefulness in patients with obstructive sleep apnea syndrome

Objective This study investigated if obstructive sleep apnea syndrome (OSAS) may be associated with higher activity in different frequency bands of the EEG during a sustained wakefulness paradigm. Methods Twelve OSA patients and 8 healthy controls were studied with the Karolinska Drowsiness Test (KDT) and subjective ratings of sleepiness (VAS and KSS) conducted every hour during 24 h of sustained wakefulness. Results The waking EEG activity, mainly in the low (0.5–7.8 Hz) and fast (12.7–29.2 Hz) frequency band, increased as time awake progressed in both groups but more obviously in OSA patients. A similar pattern was observed for rated sleepiness in both groups. Moreover, VAS ratings of alertness were closely related to the awake theta, fast alpha and beta bands in controls but not in OSA patients. Conclusions OSAS was associated with a wake-dependent increase in low (0.5–7.8 Hz) and fast (12.7–29.2 Hz) frequency range activity. Variations in behavioural sleepiness measured by VAS ratings closely reflect most of the waking EEG parameters in controls but not in OSA patients. Significance In a sustained wakefulness paradigm, higher activity in delta, theta and beta bands associated with OSAS indicates that OSA patients show marked signs of higher sleepiness and stronger efforts than controls to stay awake, even though they tend to underestimate their sleepiness.

6-Hour to 1-Year Variance of Five Global Precipitation Sets

Abstract Three-hourly time series of precipitation from three high-resolution precipitation products [Tropical Rainfall Measuring Mission (TRMM) algorithm 3B-42, the Climate Prediction Center’s morphing method (CMORPH), and the Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN)] and two reanalyses are examined for their frequency characteristics using broad and narrow variance categories. After isolating the diurnally forced peaks (at 24, 12, 8, and 6 h), the power spectra are divided into comprehensive broad bands comprising the annual (∼80 days–1 yr), intraseasonal (20 to ∼80 days), slow (6–20 days) and fast (36 h–6 days) synoptic, and high-frequency (6–36 h) periods. Global maps accounting for 100% of precipitation’s variance are analyzed to identify unique regional behaviors. Annual variability is strongest over regions affected by the seasonal migration of the intertropical convergence zone, as well as over monsoonal regions. The intraseasonal band displays off-equatorial evidence of the Madden–Julian oscillation (MJO), particularly in the Indian Ocean, but the MJO’s rainfall is partially manifested in the slow synoptic band and at higher frequencies. The fast synoptic band is particularly strong over the oceans, while high-frequency variability is enhanced over land by more extreme surface gradients. Diurnal variance is strongest at low latitudes and is pronounced over regions with well-known diurnal circulations, including mountains and coastlines. Interproduct and intermodel differences also indicate biases of the precipitation product algorithms and convective parameterizations, including a strong bias toward low-frequency variability in the relaxed Arakawa–Schubert parameterization employed by one of the reanalyses, as well as increased white-spectral characteristics over land in the precipitation products.

High frequency oscillations in limbic rat model for temporal lobe epilepsy

Recently a number of groups [1,2] have reported on the existence of pathological High frequency oscillations (HFO's) (oscillations in the frequency range of 80–200 Hz, termed as Ripple band and oscillations in the frequency range of 200 Hz and above, termed as Fast Ripple band) in the epileptic brain both in in-vivo and in-vitro experiments. Our goal in this study is to study the statistical modulation of HFOs during epileptogenesis in order to characterize their function in progression to seizures in the epileptic brain. In this study we define a HFO event as a subset of wave having significant high frequency component with low wave amplitude. HFO are detected from data recorded at a sampling rate of 12000 Hz for the entire duration of epileptogenesis which lasts anywhere from about 3–6 weeks. Statistical analysis on the HFO suggest that occurrence of HFO's occur primarily during the 12 hour dark cycle whereas the HFO's primarily seem to occur during the 12 hour day cycle in the control rat The video recording shows that the rat is primarily in active and exploratory state during the dark cycle. These observations suggest that HFO in epileptic rats are correlated with the state of arousal. Spatial correlation of HFOs in different regions of the brain is also investigated with cross-correlogram. Comparison of cross-correlogram of the post-stimulus HFO in the epileptic rat to the pre stimulus HFO (control) suggests modification in the circuitry in the hippocampus, evidence for which in in-vitro experiments were provided by [3].

Comparison of Direction and Object Selectivity of Local Field Potentials and Single Units in Macaque Posterior Parietal Cortex During Prehension

Recent studies have shown that the local field potential (LFP) can provide a simple method for obtaining an accurate measure of reaching and saccade behaviors. However, it is not clear whether this signal is equally informative with respect to more complex movements. Here we recorded LFPs and single units (SUs) from different areas in the posterior parietal cortex of macaques during a prehension task and compared LFP selectivity with SU selectivity. We found that parietal LFPs were often selective to target direction or object and that percentages of selective LFPs were similar to percentages of selective SUs. Nevertheless, SUs were more informative than LFPs in several respects. Preferred directions and objects of LFPs usually deviated from a uniform distribution, unlike preferences of SUs. Furthermore, preferences of LFPs did not reflect preferences of SUs even when the two signals were recorded simultaneously via the same electrode. Additionally, selectivity of movement-evoked LFPs appeared only after movement onset, whereas SUs frequently showed premovement selectivity. Spectral analysis revealed a lower signal-to-noise ratio of the LFP signal. Different frequency bands derived from a single LFP site showed inconsistent preferences. Significant relations with target parameters were found for all tested bands of LFP, but effects in the fast (gamma) band exhibited properties that were consistent with contamination of the LFP by residual spiking activity. Taken together, our results suggest that the LFP provides a simple method for extracting ample movement-related information. However, some of its properties make it less adequate for predicting rapidly changing movements.

A Novel Geometry-Based Feature-Selection Technique for Hyperspectral Imagery

In this letter, a geometry-based feature-selection method is proposed for efficient analysis of hyperspectral imagery. It searches the vertices that form the largest simplex iteratively in pixel space. These vertices are representative subsets of spectral bands. A distance measure is introduced in the simplex volume comparison for fast implementation of the proposed method. Fast principal component analysis and spectral band indexing are suggested for data preprocessing. This method can be implemented in supervised or unsupervised manner. It is automatic, fast, and distribution-free. Experimental results show the superiority of the proposed method in terms of quality and speed

The Repeat Domain of the Melanosomal Matrix Protein PMEL17/GP100 Is Required for the Formation of Organellar Fibers

Over 125 pigmentation-related genes have been identified to date. Of those, PMEL17/GP100 has been widely studied as a melanoma-specific antigen as well as a protein required for the formation of fibrils in melanosomes. PMEL17 is synthesized, glycosylated, processed, and delivered to melanosomes, allowing them to mature from amorphous round vesicles to elongated fibrillar structures. In contrast to other melanosomal proteins such as TYR and TYRP1, the processing and sorting of PMEL17 is highly complex. Monoclonal antibody HMB45 is commonly used for melanoma detection, but has the added advantage that it specifically reacts with sialylated PMEL17 in the fibrillar matrix in melanosomes. In this study, we generated mutant forms of PMEL17 to clarify the subdomain of PMEL17 required for formation of the fibrillar matrix, a process critical to pigmentation. The internal proline/serine/threonine-rich repeat domain (called the RPT domain) of PMEL17 undergoes variable proteolytic cleavage. Deletion of the RPT domain abolished its recognition by HMB45 and its capacity to form fibrils. Truncation of the C-terminal domain did not significantly affect the processing or trafficking of PMEL17, but, in contrast, deletion of the N-terminal domain abrogated both. We conclude that the RPT domain is essential for its function in generating the fibrillar matrix of melanosomes and that the luminal domain is necessary for its correct processing and trafficking to those organelles.

Luminescent VUV spectroscopy of [formula omitted] and [formula omitted] ions in strontium fluoride crystals

Emission and excitation spectra as well as decay curves of Er 3 + and Tm 3 + ions doped into SrF 2 crystals have been studied using time-resolved vacuum-ultraviolet spectroscopy under pulsed synchrotron radiation at 8 K. In emission spectrum for crystals doped with Er 3 + ions together with well-known emission caused by spin-forbidden 4 f 10 5 d → 4 f 11 transitions (decay constant in the microsecond range), a new fast emission band detected at 146.5 nm (decay constant is less than 0.6 ns) has been revealed. It was shown that excitation spectra of f–f and d–f emission bands for Er 3 + and Tm 3 + ions in SrF 2 have opposite behaviors in the spectral range corresponding to energy of their 4 f n - 1 5 d configurations. These peculiarities and energy transfer mechanisms were analyzed.

Spectral and complexity features of the EEG changed by visual input in a case of subcortical stroke compared to healthy controls

Objective To compare spectral and complexity characteristics of the EEG in a unique case of subcortical infarct to those seen in healthy controls. Methods Absolute and relative frequency spectra, theta/beta ratio, the brain symmetry index (BSI), Omega-complexity and synchronization likelihood were calculated of the EEG recorded in eyes closed and eyes open conditions. Results Increased absolute delta, theta, and Omega-complexity in these frequency bands, higher theta/beta ratios, and decreased relative beta activity were found in the side of the infarct. The BSI localized the excess of slow, and decrease of fast frequency activity to the area of ischemia. Following eyes opening the increase of fast and decrease of slow frequencies, the increase of Omega-complexity in the alpha and beta bands, and the decrease of synchronization likelihood for the fast frequency bands were reduced in the side of the infarct. Conclusions The subcortical infarct caused ipsilaterally increased slow, and decreased fast frequency activity accompanied by decreased synchronization of slow, increased synchronization of fast frequencies. Reduced reactivity in the ischemic side was particularly apparent for complexity measures. Significance Complexity indices of the EEG are sensitive complementary measures of electrophysiological changes caused by local lesions such as subcortical stroke.

Long‐term effects of stroke on neuronal rest activity in rolandic cortical areas

To understand the relationship between neuronal function and clinical state in the framework of stroke, the long-term poststroke rolandic spontaneous neuronal activity was studied by means of magnetoencephalography. Fifty-six patients who had suffered a unilateral stroke within the middle cerebral artery were enrolled. Median time since stroke was 2.8 years. In association with lesion features and clinical picture, total and relative band powers and the spectral entropy were analyzed in the affected (AH) and unaffected (UH) hemispheres in comparison with an age-matched control group. An increase of absolute and relative slow band powers and a reduction of relative fast band powers were found in patients' AH with respect to both UH and control values. Absolute delta band was higher than in controls also in UH. New findings were the increase of rolandic rest activity power also in the alpha band and the decrease of spectral entropy in AH with respect to both UH and control values. Moreover, our results in chronic stroke patients indicate frequency-selective alterations related to specific dysfunctions: global clinical status was mostly impaired in patients with larger lesions and increased total and slow band activity powers, whereas hand functionality was mostly disrupted in patients with subcortical involvement and reduction of high-frequency rhythms and spectral entropy. Total power increase and spectral richness decrease are in agreement with a higher synchrony of local neuronal activity, a reduction of the intracortical inhibitory network's efficiency, and an increase of neuronal excitability.

The Effect of Donepezil on Sleep and REM Sleep EEG in Patients with Alzheimer Disease: A Double-Blind Placebo-Controlled Study

Examine the effects of donepezil on sleep and rapid eye movement (REM) sleep electroencephalogram (EEG) in patients with Alzheimer disease, using polysomnography, and the correlation between REM sleep EEG parameters and cognitive scores. Randomized, double-blind, placebo-controlled design. Two sleep research centers, University Hospital. Thirty-five patients with mild to moderate Alzheimer disease, allocated to 2 groups: donepezil treated (n=17) and placebo treated (n=18). Patients were administered donepezil or placebo. Polysomnography with REM sleep EEG spectral analysis and cognitive evaluation using the Alzheimer Disease Assessment Scale, cognitive subscale, were performed at baseline and after 3 and 6 months. Slowing ratio was the ratio between slow and fast EEG frequency bands. Cognitive and sleep data were analyzed using analysis of variance. Correlations between cognitive improvement and REM sleep EEG were also calculated. REM sleep increased significantly after 3 and 6 months of donepezil treatment compared with baseline and placebo (p < .01). Overall theta (p = .04), frontal theta (p < .01) and frontal delta (p = .03) absolute power during REM sleep decreased after 6 months of donepezil treatment. The occipital slowing ratio decreased during treatment (p = .04). REM sleep overall and frontal and centroparietal alpha absolute power significantly correlated with the cognitive improvement rate on the Alzheimer Disease Assessment Scale, cognitive subscale (r = 0.75, r = 0.71, r = 0.78); p < .01). Donepezil treatment enhanced REM sleep and reduced slow frequencies of REM sleep EEG, suggesting a possible action upon REM sleep-related cholinergic neurons in patients with Alzheimer disease. Furthermore, REM sleep alpha power may predict the cognitive response to donepezil.

Acceleration of narrow band method and its application to topology-adaptive 3D geometrical modeling

A method for increasing the speed of surface shape evolution called the fast narrow band method and a topology-adaptive geometrical modeling method that uses the fast narrow band method are proposed. Although there have been many reports of the use of the level set method as an effective method for topology-adaptive geometrical modeling, the methods suffers from the problem that the computational cost is very large. The narrow band method has been widely used as the most general method for increasing the speed of the level set method, but it has not been found to sufficiently reduce the computational cost. The proposed fast narrow band method retains the precision of the narrow band method while reducing the computational cost by using distance information to increase the efficiency of the search process. Experiments are performed on scenes containing objects with holes and scenes containing multiple objects, and a five-fold increase in speed is achieved over the Hermes algorithm, which was previously the fastest implementation of the level set method. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(11): 68–78, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20130

Optical rectification effect in nano-carbon CVD films

We report on the study of the optical rectification effect in the nano-carbon (nC) films. The effective second-order susceptibility of the film is found to be 2 × 10 − 5 CGSE, which is two orders higher than that of the conventional nonlinear crystals. The nC films were obtained by CVD method and consist of nano-sized graphite crystallites preferably oriented along the substrate normal. In the experiment, we measure the potential difference between two electrodes attached to surface of the nC film, which is irradiated by a nanosecond laser pulse. The temporal profile of measured electric signal well reproduces the envelope of incident light pulse. We found that the observed in the experiment dependence of the light-induced voltage on intensity, polarization, wavelength and angle of incidence are well described in terms of the optical rectification in nonlinear optical media. The experimental results indicate that the effect may originate from the quadrupole and magnetic dipole mechanism of optical nonlinearity. In the nC films this mechanism may be pronounced because of the strong delocalization of sp 2 orbitals within the graphitic layers. The observed nonlinear optical effect indicates that nC films is a prospective material to be employed in fast wide band optical detectors and position sensitive devices.

Interaction between concentric eye‐walls in super typhoon Winnie (1997)

AbstractSuper typhoon Winnie had one of the largest eye‐walls ever recorded in the western Pacific Ocean. The diameter of the outer eye‐wall reached 370 km when Winnie passed through Okinawa on 16 August 1997. Observations revealed a 24‐hour intensity cycle of concentric eye‐walls after the large eye‐wall formed. Using the Penn State University/National Center for Atmospheric Research mesoscale model MM5 with 3 km grid horizontal spacing on the finest nested mesh, Winnie was successfully simulated in terms of concentric eye‐walls, spiral rain bands in the moat and the cycle of concentric eye‐walls.The life cycle of concentric eye‐walls is found to be associated with vortex Rossby wave propagation in the moat. The propagation properties of the PV (rainfall) spiral bands are found to be consistent with predictions using vortex Rossby theory. The initial inward vorticity gradient at the inner edge of the outer eye‐wall and outward vorticity gradient at the outer edge of the inner eye‐wall support inward and outward PV (rainfall) spiral bands, respectively, in the moat at the lower level. At the middle level, only an outward vorticity gradient exists at the outer edge of the inner eye‐wall, which permits the development of an outward PV band in the moat at initial time. The inward spiral PV (rain) band moves faster than the outward PV (rain) band and both of them propagate cyclonically. At 09 h, when the fast inward PV band catches up to the slow outward PV band, the slow outward rain band is replaced by the fast inward rain band, resulting in a well‐developed and independent inner eye‐wall at 14 h. After the vorticity gradient near the inner eye‐wall becomes stronger than that near the outer eye‐wall at lower level, the whole convective core is attracted to the outer eye‐wall. It finally merges with it at 37 h, leaving a weak vortex in the centre. The concentric eye‐walls of Winnie interact with each other through vortex Rossby waves. Copyright © 2005 Royal Meteorological Society.

Triton-polyacrylamide gel electrophoresis and leucine aminopeptidase activity staining detect Triton-slowed bands including high-molecular-mass aminopeptidase N (CD13) isoform in cholestatic patient sera

Background Western blotting of aminopeptidase N (APN) detects a high-molecular-mass isoform (260 kDa) [M. Kawai, Y. Otake, Y. Hara High-molecular-mass isoform of aminopeptidase N/CD13 in serum from cholestatic patients. Clin Chim Acta 330 (2003) 141–149] in cholestatic patient serum but is time-consuming. Methods Human sera were electrophoresed on polyacrylamide gel containing Triton-X100 (Triton-PAGE) and stained with leucine-B-naphthylamide (LAP-staining). The stained bands were eluted from the gel, treated with N- and O-glycosidase if necessary, and analyzed by Western blotting [M. Kawai, Y. Otake, Y. Hara High-molecular-mass isoform of aminopeptidase N/CD13 in serum from cholestatic patients. Clin Chim Acta 330 (2003) 141–149]. Results Triton-PAGE and LAP-staining clearly detected fast bands in all the sera examined. Almost parallel with leucine aminopeptidase activity, slow bands were strongly stained in all 11 cholestatic patients but clearly stained in 3 out of 14 patients with hepatobiliary diseases other than cholestasis. PAGE with various concentrations of Triton showed that Triton slows down slow bands but not fast bands. Western blotting showed that Triton-PAGE-slow bands of cholestasis contained 140 and 260-kDa APN and that fast bands were slightly smaller than monomer-size slow bands after glycosidase treatment. Conclusions Less time-consuming than Western blotting, Triton-PAGE and LAP-staining detect novel APN bands slowed by Triton and partly composed of the high-molecular-mass isoform in cholestasis. The slow bands seem to be homodimers of APN with transmembrane anchors. The polypeptide of the fast band seems to be processed differently from that of the slow band.

Correction of muscle artefacts in the EEG power spectrum

Objective To provide a method for correcting muscle artefacts in fast band power at EEG derivations. Methods We define an indicator of surface EMG as power in the band 51.0–69.0 Hz (‘muscle power’). This indicator is used to approximately eliminate the contribution of muscle activity on fast band power via a regression model. Results (1) Patients show a larger proportion of muscle activity in fast band power. (2) There is a clear topographic pattern, frontal–temporal derivations being most susceptible to EMG artefacts. (3) The contribution of surface EMG can be drastically reduced by the proposed correction method. (4) Without correction, results for fast bands can be biased when e.g. comparing control and patient groups and the proposed correction method by and large eliminates this bias. Conclusions It is advisable to correct the quantitative EEG reflecting fast activity for the extent of EMG artefacts. Significance To render the quantitative EEG more valid as an indicator of cerebral activity.