Home About us Contact
|
Home About us Contact | ||
|
|
||
Frequency Analysis (frequency + analysis)
Kinds of Frequency Analysis Selected AbstractsDynamic Changes of Ictal High-Frequency Oscillations in Neocortical Epilepsy: Using Multiple Band Frequency AnalysisEPILEPSIA, Issue 2 2007Ayako Ochi Summary:,Purpose: To characterize the spatial and temporal course of ictal high-frequency oscillations (HFOs) recorded by subdural EEG in children with intractable neocortical epilepsy. Methods: We retrospectively studied nine children (four girls, five boys; 4,17 yr) who presented with intractable extrahippocampal localization-related epilepsy and who underwent extraoperative video subdural EEG (1000 Hz sampling rate) and cortical resection. We performed multiple band frequency analysis (MBFA) to evaluate the frequency, time course, and distribution of ictal HFOs. We compared ictal HFO changes before and after clinical onset and postsurgical seizure outcomes. Results: Seventy-eight of 79 seizures showed HFOs. We observed wide-band HFOs (,250Hz, ,120 electrodes) in six patients either with partial seizures alone (three patients) or with epileptic spasms (three patients). Three patients with partial seizures that secondarily generalized had wide-band HFOs (,170 Hz) before clinical onset and sustained narrow-band HFOs (60,164 Hz) with electrodecremental events after clinical onset (,28 electrodes). In four postoperatively seizure-free patients, more electrodes recorded higher-frequency HFOs inside the resection area than outside before and after clinical seizure onset. In five patients with residual seizures, electrodes recorded more HFOs that were of higher or equal frequency outside the surgical area than inside after clinical onset. Conclusion: For partial seizures alone and epileptic spasms, more electrodes recorded only wide-band HFOs; for partial seizures that secondarily generalized, fewer electrodes recorded wide-band HFOs, but in these seizures electrodes also recorded subsequent sustained narrow-band ictal HFOs. Resection of those brain regions having electrodes with ictal, higher HFOs resulted in postsurgical seizure-free outcomes. [source] Farm Size Growth and Participation in Agri-environmental Schemes: A Configural Frequency Analysis of the Swiss CaseJOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2005Stefan Mann Q15 Abstract This paper examines the relationship between farm growth and participation in agri-environmental schemes, using the example of meadow extensification schemes in Switzerland. As a result of small farm sizes in Swiss agriculture, theory would suggest that economies of scale are considerable for market production activities, so that for growing farms it would be rational to intensify. Configural frequency analysis is used to identify and describe combinations of farm size development and proportion of meadows placed under agri-environmental schemes. In the Swiss case, growing farms are likely to reduce their participation, whereas shrinking farms have a growing share of their meadows under extensification schemes. [source] Frequency Analysis of Atrial Electrograms Identifies Conduction Pathways from the Left to the Right Atrium During Atrial Fibrillation,Studies in Two Canine ModelsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2009KYUNGMOO RYU Ph.D. Studies of atrial fibrillation (AF) have demonstrated that a stable rhythm of very short cycle length in the left atrium (LA) can cause fibrillatory conduction in the rest of the atria. We tested the hypothesis that fast Fourier transform (FFT) analysis of atrial electrograms (AEGs) during this AF will rapidly and reliably identify LA-to-right atrium (RA) conduction pathway(s) generated by the driver. Methods and Results: During induced atrial tachyarrhythmias in the canine sterile pericarditis and rapid ventricular pacing-induced congestive heart failure models, 380,404 AEGs were recorded simultaneously from epicardial electrodes on both atria. FFT analysis of AEGs during AF demonstrated a dominant frequency peak in the LA (driver), and multiple frequency peaks in parts of the LA and the most of the RA. Conduction pathways from the LA driver to the RA varied from study-to-study. They were identified by the presence of multiple frequency peaks with one of the frequency peaks at the same frequency as the driver, and traveled (1) inferior to the inferior vena cava (IVC); (2) between the superior vena cava and the right superior pulmonary vein (RSPV); (3) between the RSPV and the right inferior pulmonary vein (RIPV); (4) between the RIPV and the IVC; and (5) via Bachmann's bundle. Conduction pathways identified by FFT analysis corresponded to the conduction pathways found in classical sequence of activation mapping. Computation time for FFT analysis for each AF episode took less than 5 minutes. Conclusion: FFT analysis allowed rapid and reliable detection of the LA-to-RA conduction pathways in AF generated by a stable and rapid LA driver. [source] Surface Atrial Frequency Analysis in Patients with Atrial Fibrillation:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2004A Tool For Evaluating the Effects of Intervention Introduction: The aims of this study were to evaluate (1) principal component analysis as a technique for extracting the atrial signal waveform from the standard 12-lead ECG and (2) its ability to distinguish changes in atrial fibrillation (AF) frequency parameters over time and in response to pharmacologic manipulation using drugs with different effects on atrial electrophysiology. Methods and Results: Twenty patients with persistent AF were studied. Continuous 12-lead Holter ECGs were recorded for 60 minutes, first, in the drug-free state. Mean and variability of atrial waveform frequency were measured using an automated computer technique. This extracted the atrial signal by principal component analysis and identified the main frequency component using Fourier analysis. Patients were then allotted sequentially to receive 1 of 4 drugs intravenously (amiodarone, flecainide, sotalol, or metoprolol), and changes induced in mean and variability of atrial waveform frequency measured. Mean and variability of atrial waveform frequency did not differ within patients between the two 30-minute sections of the drug-free state. As hypothesized, significant changes in mean and variability of atrial waveform frequency were detected after manipulation with amiodarone (mean: 5.77 vs 4.86 Hz; variability: 0.55 vs 0.31 Hz), flecainide (mean: 5.33 vs 4.72 Hz; variability: 0.71 vs 0.31 Hz), and sotalol (mean: 5.94 vs 4.90 Hz; variability: 0.73 vs 0.40 Hz) but not with metoprolol (mean: 5.41 vs 5.17 Hz; variability: 0.81 vs 0.82 Hz). Conclusion: A technique for continuously analyzing atrial frequency characteristics of AF from the surface ECG has been developed and validated. [source] Middle School Mathematics Teachers' Beliefs About Inclusion of Students with Learning DisabilitiesLEARNING DISABILITIES RESEARCH & PRACTICE, Issue 2 2006Janet R. DeSimone The purpose of this descriptive study was to investigate middle school general education mathematics teachers' beliefs and self-perceived knowledge regarding teaching students with learning disabilities (LD) in inclusive classrooms. Teacher beliefs regarding administrative support and higher education teacher preparation were also examined. The Survey on Teaching Mathematics to Students With Learning Disabilities in Middle School was completed by 228 sixth-, seventh-, and eighth-grade general education mathematics inclusion teachers from 19 states. In addition, telephone interviews were conducted with a subset of 26 survey respondents. Frequency analyses were performed on the survey data, with ,2 tests comparing teachers on demographic variables. Follow-up interview responses were summarized to elaborate on the major research questions. The findings revealed three central issues: (1) teachers had a limited understanding of the mathematics learning needs of students with LD, (2) teacher collaboration was judged to be the most beneficial and available resource by general educators teaching students with LD in inclusive mathematics classrooms, and (3) teachers did not feel that teacher education programs at the preservice level and professional development at the inservice level were adequate in preparing them for teaching students with LD in inclusive mathematics classrooms. Implications and recommendations for teacher preparation and program implementation are provided. [source] Frequency analyses of gastric pH in control and gastro-oesophageal reflux disease subjects treated with a proton-pump inhibitorALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 11-12 2004J. D. Gardner Summary Background :,We are unaware of any solid theoretical or pathophysiological basis for selecting pH 4 or any other pH value to assess gastric acidity. Aim :,To examine the frequency of different gastric pH values in control and GERD subjects. Methods :,Gastric pH was measured for 24 h in 26 control subjects, 26 gastro-oesophageal reflux disease subjects at baseline and the same 26 gastro-oesophageal reflux disease subjects during treatment with a proton-pump inhibitor. Histograms were constructed using the 21 600 values generated from each recording and bins of 0.25 pH units. Results :,The distribution of gastric pH values in gastro-oesophageal reflux disease subjects was significantly different from that in controls and in some instances the distributions detected significant differences that were not detected by integrated acidity. Proton-pump inhibitor treatment significantly altered the distribution of gastric pH values and the nature of this alteration during the postprandial period was different from that during the nocturnal period. Using time pH,4 can significantly underestimate the magnitude of inhibition of gastric acidity caused by a proton-pump inhibitor. Conclusions :,The distribution of gastric pH values provides a rationale for selecting a particular pH value to assess gastric acidity. In some instances, the distribution of gastric pH values detects significant differences between gastro-oesophageal reflux disease and normal subjects that are not detected by integrated acidity. [source] Frequency analysis for predicting 1% annual maximum water levels along Florida coast, USHYDROLOGICAL PROCESSES, Issue 23 2008Sudong Xu Abstract In the Coastal Flood Insurance Study by the Federal Emergency Management Agency (FEMA, 2005), 1% annual maximum coastal water levels are used in coastal flood hazard mitigation and engineering design in coastal areas of USA. In this study, a frequency analysis method has been developed to provide more accurate predictions of 1% annual maximum water levels for the Florida coast waters. Using 82 and 94 years of annual maximum water level data at Pensacola and Fernandina, performances of traditional frequency analysis methods, including advanced method of Generalized Extreme Value distribution method, have been evaluated. Comparison with observations of annual maximum water levels with 83 and 95 years of return periods indicate that traditional methods are unable to provide satisfactory predictions of 1% annual maximum water levels to account for hurricane-induced extreme water levels. Based on the characteristics of annual maximum water level distribution of Pensacola and Fernandina stations, a new probability distribution method has been developed in this study. Comparison with observations indicates that the method presented in this study significantly improves the accuracy of predictions of 1% annual maximum water levels. For Fernandina station, predictions of extreme water level match well with the general trend of observations. With a correlation coefficient of 0·98, the error for the maximum observed extreme water level of 3·11 m (National Geodetic Vertical Datum) with 95 years of return period is 0·92%. For Pensacola station, the prediction error for the maximum observed extreme water level with a return period of 83 years is 5·5%, with a correlation value of 0·98. The frequency analysis has also been reasonably compared to the more costly Monte Carlo simulation method. Copyright © 2008 John Wiley & Sons, Ltd. [source] Temporal and spatial variation of annual rainfall on the island of Crete, GreeceHYDROLOGICAL PROCESSES, Issue 10 2003S. Naoum Abstract Annual rainfall records from the island of Crete in Greece were used with the aid of a geographical information system (GIS) to study the temporal and spatial rainfall characteristics. The GIS was used to produce a digital elevation model, delineate watersheds and estimate the areal rainfall from a network of raingauges by using different interpolation schemes. The rainfall,elevation correlation was significant, suggesting an orographic type of precipitation for the island. The rainfall records for the majority of the stations were found to fit the normal distribution. Deviation from normal for the rest of the records was attributed to the wettest year of 1977,1978. The year 1989,1990 was the driest, and most rainfall records showed a decrease in rainfall over 30 years with higher negative rainfall gradients at the higher elevations. Frequency analysis of the rainfall records was used to estimate areal rainfall for the island of Crete and its main watersheds for return periods of 2, 5 and 10 years. Copyright © 2003 John Wiley & Sons, Ltd. [source] Development of recursive interpolated D/FFT for on-line and highly accurate frequency analysisIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2008Takashi Kuraishi Student Member Abstract Frequency analysis of digital signals based on discrete/fast Fourier transform (D/FFT) inevitably has some inherent drawbacks such as short-and long-range leakage. As one of the methods to overcome the above drawbacks, interpolated discrete/fast Fourier transform (IpD/FFT) has been proposed. IpD/FFT has the ability to improve accuracy considerably. We proposed IpD/FFT, combined with recursive algorithm (RA), to achieve on-line calculation. By evaluating the errors of the proposed method due to short-and long-range leakage, we showed that the proposed method can provide more accurate performance compared with recursive DFT (R-DFT). © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Instrumental pressure observations and atmospheric circulation from the 17th and 18th centuries: London and ParisINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2001V.C. Slonosky Abstract Daily pressure observations recorded by William Derham (1657,1735) at Upminster, Essex (near London), from 1697 to 1706 and 1708 have been corrected, converted to modern units and the Gregorian calendar, and adjusted for homogeneity. These pressure readings have been compared with previously published contemporary observations from Paris, and the two sets of early instrumental data used to calculate a daily series of the pressure difference between Paris and London. Frequency analysis of the daily series reveals that reversals of the south,north pressure gradient and easterly winds were more common from 1697 to 1708 than during the 1990s. Monthly mean values of Paris,London pressure differences have been compared with previously published monthly mean reconstructed surface pressure maps and to a reconstructed North Atlantic Oscillation (NAO) index. There is a good agreement between the strength and direction of monthly mean flow between London and Paris estimated from the circulation maps and the sign and magnitude of the Paris,London westerly flow index, but the correlation between the Paris,London index, known to be a good proxy for European zonal circulation, and the reconstructed NAO index, is low (0.2). Correlations between the monthly mean Paris,London zonal circulation index and central England temperatures suggest a strong relationship during winter and late summer from 1697 to 1708. The meticulous daily instrumental observations and the monthly and seasonal climate descriptions of Derham, his collection of instrumental observations and climatic descriptions from contemporary observers throughout Europe, and his early theories on the causes of climate change make his publications a valuable source of information for studies on climate during the early instrumental period. It is hoped that more of Derham's papers related to weather and climate may eventually come to light. Copyright © 2001 Royal Meteorological Society. [source] Vitamin D Hormone Inhibits Osteoclastogenesis In Vivo by Decreasing the Pool of Osteoclast Precursors in Bone MarrowJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2002Takeshi Shibata Abstract Previous observations that vitamin D hormone induces the expression of the receptor activator of nuclear factor ,B (NF-,B) ligand (RANKL), thereby stimulating osteoclastogenesis in vitro, led to the widespread belief that 1,,25-dihydroxyvitamin D3 [1,,25(OH)2D3] is a bone-resorbing hormone. Here, we show that alfacalcidol, a prodrug metabolized to 1,,25(OH)2D3, suppresses bone resorption at pharmacologic doses that maintain normocalcemia in an ovariectomized (OVX) mouse model of osteoporosis. Treatment of OVX mice with pharmacologic doses of alfacalcidol does not increase RANKL expression, whereas toxic doses that cause hypercalcemia markedly reduce the expression of RANKL. When bone marrow (BM) cells from OVX mice were cultured with sufficient amounts of macrophage colony-stimulating factor (M-CSF) and RANKL, osteoclastogenic activity was higher than in sham mice. Marrow cultures from alfacalcidol- or estrogen-treated OVX mice showed significantly less osteoclastogenic potential compared with those from vehicle-treated OVX mice, suggesting that the pool of osteoclast progenitors in the marrow of vitamin D-treated mice as well as estrogen-treated mice was decreased. Frequency analysis showed that the number of osteoclast progenitors in bone marrow was increased by OVX and decreased by in vivo treatment with alfacalcidol or estrogen. We conclude that the pharmacologic action of active vitamin D in vivo is to decrease the pool of osteoclast progenitors in BM, thereby inhibiting bone resorption. Because of its unusual activity of maintaining bone formation while suppressing bone resorption, in contrast to estrogens that depress both processes, vitamin D hormone and its bone-selective analogs may be useful for the management of osteoporosis. [source] Motion analysis of stereotyped hand movements in Rett syndromeJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2 2003M. Wright Abstract Background Rett syndrome is a genetic developmental disorder, and stereotyped hand movements are a striking feature of this condition. The aim of the present study was to subject these movements to objective analysis and compare the results in one girl at different ages. Method The hand movements of a 10-year-old girl with Rett syndrome were subjected to accurate, three-dimensional (3D) computerized motion analysis and compared to two-dimensional (2D) video analysis of the same girl at 3 years of age. Results Three-dimensional computerized analysis revealed regular patterns with strong coupling between the hands. Frequency analysis showed a dominant frequency at 1.2 Hz, with a higher component at 2.4 Hz that may relate to the activity of basic rhythm generators. The same coupling characteristics were extracted from standard, 2D video recordings made at the same time as the 3D capture. Conclusion An informal video of the same girl taken when she was 3 years of age was analysed in the same way as the 2D video and showed the same characteristics, indicating the possible future use of automated video analysis for early screening and intervention evaluation. [source] An Assessment of the Terminology Used by Diplomates and Students to Describe the Character of Equine Mitral and Aortic Valve Regurgitant Murmurs: Correlations with the Physical Properties of the SoundsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2003Jonathan M. Naylor Twenty students and 16 diplomates listened to 7 recordings made from 7 horses with either aortic (n = 3) or mitral valve (n = 4) regurgitant murmurs. A total of 30 different terms were used to describe the character of these murmurs. However, only 4 terms were used in a repeatable and consistent manner. Most people described the character of a given mitral or aortic valve murmur with 1 or 2 terms. Diplomates drew from a pool of terms that was about half the size of that used by students,.1 ±2.0 terms for diplomats (mean ±1 SD) versus 13.1 ±1.8 terms for students (P < .001). Only blowing, honking, buzzing, and musical were markedly associated with the recording played. Frequency analysis of the murmurs allowed them to be classified as containing harmonics (n = 4) or not containing harmonics (n = 3). Blowing was used to describe murmurs without harmonics on 39 of 48 occasions and corresponds to the term noisy used in some older descriptions of equine murmurs. Honking, musical, and buzzing were markedly associated with murmurs that contained harmonics; these terms were used 23, 13, and 12 of a possible 64 times, respectively. The frequency of buzzing and honking murmurs (72.7 ±9.3 and 88.4 ±46.3 Hz, respectively) was markedly lower than that of musical murmurs (156.8 ±81.1 Hz) (all P values <.01). Honking murmurs (0.392 ±0.092 seconds) were shorter than those described as buzzing or musical (0.496 ±0.205 and 0.504 ±0.116 seconds, respectively). The data suggest that the terminology for the character of aortic and mitral regurgitant murmurs should be restricted to 4 terms: blowing, honking, buzzing, and musical. Honking, buzzing, and musical describe murmurs with a peak dominant frequency and harmonics; blowing describes murmurs without a peak frequency. Effective communication could be enhanced by playing examples of reference sounds when these terms are taught so that nomenclature is used more uniformly. Key words: Cardiac; Heart; Learning; Meaning. [source] The physiology of insect auditory afferentsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2004Andrew C. Mason Abstract This review presents an overview of the physiology of primary receptors serving tympanal hearing in insects. Auditory receptor responses vary with frequency, intensity, and temporal characteristics of sound stimuli. Various insect species exploit each of these parameters to differing degrees in the neural coding of auditory information, depending on the nature of the relevant stimuli. Frequency analysis depends on selective tuning in individual auditory receptors. In those insect groups that have individually tuned receptors, differences in physiology are correlated with structural differences among receptors and with the anatomical arrangement of receptors within the ear. Intensity coding is through the rate-level characteristics of tonically active auditory receptors and through variation in the absolute sensitivities of individual receptors (range fractionation). Temporal features of acoustic stimuli may be copied directly in the timing of afferent responses. Salient signal characteristics may also be represented by variation in the timing of afferent responses on a finer temporal scale, or by the synchrony of responses across a population of receptors. Microsc. Res. Tech. 63:338,350, 2004. © 2004 Wiley-Liss, Inc. [source] Frequency analysis and clinical characterization of different types of spinocerebellar ataxia in Serbian patientsMOVEMENT DISORDERS, Issue 2 2006a T. Draga Abstract The relative frequencies of different spinocerebellar ataxias (SCAs) vary widely among different ethnic groups, presumably due to a founder effect. We investigated the relative prevalence of SCA1,3, 6,8, 12, 17; dentate,rubro,pallidoluysian atrophy; and Friedreich's ataxia (FRDA) in Serbian patients with adult-onset (>20 years of age) hereditary and sporadic SCAs, and compared clinical features of patients with genetically confirmed SCAs. A total of 108 patients from 54 families (38 apparently dominant [ADCA] and 16 apparently recessive) with adult-onset hereditary ataxia and 75 apparently sporadic patients were assessed. Of 38 families with ADCA, 13 (34%) were positive for an expansion in an SCA1 and 5 families (13%) for an expansion in an SCA2 allele. In 20 families (53%), no expansions have been identified in any of the analyzed genes. Gaze palsy, spasticity, and hyperreflexia were significantly more common in SCA1, whereas slow saccades, hypotonia, hyporeflexia, and dystonia prevailed in SCA2 patients. Among the 16 families with an apparently recessive mode of ataxia inheritance, 4 (25%) were identified as having the FRDA mutation. Ataxia-causing mutations were identified in 8 (10.6%) of patients with apparently sporadic adult-onset ataxia. © 2005 Movement Disorder Society [source] Dynamic links between theta executive functions and alpha storage buffers in auditory and visual working memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2010Masahiro Kawasaki Abstract Working memory (WM) tasks require not only distinct functions such as a storage buffer and central executive functions, but also coordination among these functions. Neuroimaging studies have revealed the contributions of different brain regions to different functional roles in WM tasks; however, little is known about the neural mechanism governing their coordination. Electroencephalographic (EEG) rhythms, especially theta and alpha, are known to appear over distributed brain regions during WM tasks, but the rhythms associated with task-relevant regional coupling have not been obtained thus far. In this study, we conducted time,frequency analyses for EEG data in WM tasks that include manipulation periods and memory storage buffer periods. We used both auditory WM tasks and visual WM tasks. The results successfully demonstrated function-specific EEG activities. The frontal theta amplitudes increased during the manipulation periods of both tasks. The alpha amplitudes increased during not only the manipulation but also the maintenance periods in the temporal area for the auditory WM and the parietal area for the visual WM. The phase synchronization analyses indicated that, under the relevant task conditions, the temporal and parietal regions show enhanced phase synchronization in the theta bands with the frontal region, whereas phase synchronization between theta and alpha is significantly enhanced only within the individual areas. Our results suggest that WM task-relevant brain regions are coordinated by distant theta synchronization for central executive functions, by local alpha synchronization for the memory storage buffer, and by theta,alpha coupling for inter-functional integration. [source] Determination of regional net radiation and soil heat flux over a heterogeneous landscape of the Tibetan PlateauHYDROLOGICAL PROCESSES, Issue 15 2002Yaoming Ma Abstract This paper explores the potential for documenting regional fields of surface energy fluxes over the Tibetan plateau using published algorithms and previously calibrated empirical formulae with data from NOAA-14 AVHRR and atmospheric data collected during the GAME-Tibet field experiment. Comparison with observations at three field sites suggests errors in the resulting estimates are less than 10% in the clear sky conditions necessary for application of this approach. Because of the need for clear skies, it was only possible to calculate the desired regional fields for one satellite scene during the 5 month study period. Maps of surface energy fluxes, and frequency analyses of these maps, are presented for this scene. The need for an alternative, more consistently applicable, satellite-based method to map surface energy fields is highlighted. Copyright © 2002 John Wiley & Sons, Ltd. [source] Prevalence of pigmentary disorders and their impact on quality of life: a prospective cohort studyJOURNAL OF COSMETIC DERMATOLOGY, Issue 3 2008Anne Taylor PA-S Summary Background, Pigmentary disorders are commonly seen in dermatology practice and can have a negative psychosocial impact on patients. Objective, This study aims to examine the prevalence of pigmentary disorders and their level of psychological and physical impact on patients. Methods, A prospective cohort study involved a sample of 140 patients undergoing skin exams at a private dermatology practice in North Carolina. Patient demographics and pigmentary diagnoses were obtained, and participants were asked to fill out a skin discoloration impact evaluation questionnaire. Descriptive and frequency analyses were performed. Results, Around 80% of the participants were diagnosed with one or more pigmentary disorders. About 47.3% of patients admitted of feeling self-conscious about their skin to some degree, 21.8% felt others focused on their skin, 32.7% felt unattractive because of their skin, 32.7% put effort into hiding pigment changes, and 23.6% felt their skin affected their activities. A limitation was the lack of diversity in the population studied (gender and skin type). Conclusions, Pigmentary disorders such as melasma, vitiligo, and lentigo pose significant negative impact on a person's health-related quality of life. Hence, there is a need for effective treatments of pigmentary disorders based on their prevalence and effect on quality of life. Healthcare providers should consider the impact of pigmentary disorders on health-related quality of life and educate patients on possible treatments. [source] Enhanced phylogeographic information about Austrian brown trout populations derived from complete mitochondrial control region sequencesJOURNAL OF FISH BIOLOGY, Issue 2 2003N. Duftner Complete DNA sequences of the control region revealed a more fine-scale genetic structuring within and among Austrian brown trout Salmo trutta populations providing the opportunity for gene frequency analyses in the phylogeographic context. Ninety-two individuals (75%) were assigned to nine Danubian haplotypes and 31 individuals (25%) comprised seven Atlantic haplotypes of northern European origin. Three of the Atlantic haplotypes were also found in an Austrian hatchery breeding stock. [source] Evidence for Changing Flood Risk in New England Since the Late 20th Century,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2009Mathias J. Collins Abstract:, Long-term flow records for watersheds with minimal human influence have shown trends in recent decades toward increasing streamflow at regional and national scales, especially for low flow quantiles like the annual minimum and annual median flows. Trends for high flow quantiles are less clear, despite recent research showing increased precipitation in the conterminous United States over the last century that has been brought about primarily by an increased frequency and intensity of events in the upper 10th percentile of the daily precipitation distribution , particularly in the Northeast. This study investigates trends in 28 long-term annual flood series for New England watersheds with dominantly natural streamflow. The flood series are an average of 75 years in length and are continuous through 2006. Twenty-five series show upward trends via the nonparametric Mann-Kendall test, 40% (10) of which are statistically significant (p < 0.1). Moreover, an average standardized departures series for 23 of the study gages indicates that increasing flood magnitudes in New England occurred as a step change around 1970. The timing of this is broadly synchronous with a phase change in the low frequency variability of the North Atlantic Oscillation, a prominent upper atmospheric circulation pattern that is known to effect climate variability along the United States east coast. Identifiable hydroclimatic shifts should be considered when the affected flow records are used for flood frequency analyses. Special treatment of the flood series can improve the analyses and provide better estimates of flood magnitudes and frequencies under the prevailing hydroclimatic condition. [source] Flow regime determination in horizontal hydrotransport using non-intrusive acoustic probesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Katherine Albion Abstract A variety of flow regimes may be observed in the hydrotransport of solids. Maintaining a consistent operation requires rapid detection of any change in flow regime. The objective of this study was to develop reliable, non-intrusive, and on-line methods for flow regime detection in a hydrotransport pipe based on acoustic measurements. Slurries were transported in a 0.05 m diameter stainless steel hydrotransport pipe. Acoustic measurements were recorded by microphones along the length of the horizontal pipe. Two flow regimes were observed: suspended solids flow and flow over settled solids. Cycle and frequency analyses of the acoustic signals provided reliable identification of these flow regimes. Plusieurs régimes d'écoulement peuvent être observés dans le transport hydraulique des solides. Le maintien d'un fonctionnement consistant nécessite la détection rapide de tout changement dans le régime d'écoulement. L'objectif de cette étude est de développer des méthodes fiables, non intrusives et en continu pour la détection des régimes d'écoulement dans une conduite de transport hydraulique reposant sur des mesures acoustiques. Les suspensions ont été transportées dans une conduite de transport hydraulique en acier inoxydable de 0,05 m de diamètre. Les mesures acoustiques ont été enregistrées par des microphones le long de la conduite horizontale. Deux régimes d'écoulement ont été observés : l'écoulement de solides suspendus et l'écoulement au-dessus des solides déposés. Les analyses de cycle et de fréquence des signaux acoustiques fournissent une identification fiable de ces régimes d'écoulement. [source] Contributions of spectral frequency analyses to the study of P50 ERP amplitude and suppression in bipolar disorder with or without a history of psychosisBIPOLAR DISORDERS, Issue 7 2008Christine A Carroll Objective:, The present study investigated event-related brain potential (ERP) indices of auditory processing and sensory gating in bipolar disorder and subgroups of bipolar patients with or without a history of psychosis using the P50 dual-click procedure. Auditory-evoked activity in two discrete frequency bands also was explored to distinguish between sensory registration and selective attention deficits. Methods:, Thirty-one individuals with bipolar disorder and 28 non-psychiatric controls were compared on ERP indices of auditory processing using a dual-click procedure. In addition to conventional P50 ERP peak-picking techniques, quantitative frequency analyses were applied to the ERP data to isolate stages of information processing associated with sensory registration (20,50 Hz; gamma band) and selective attention (0,20 Hz; low-frequency band). Results:, Compared to the non-psychiatric control group, patients with bipolar disorder exhibited reduced S1 response magnitudes for the conventional P50 peak-picking and low-frequency response analyses. A bipolar subgroup effect suggested that the attenuated S1 magnitudes from the P50 peak-picking and low-frequency analyses were largely attributable to patients without a history of psychosis. Conclusions:, The analysis of distinct frequency bands of the auditory-evoked response elicited during the dual-click procedure allowed further specification of the nature of auditory sensory processing and gating deficits in bipolar disorder with or without a history of psychosis. The observed S1 effects in the low-frequency band suggest selective attention deficits in bipolar patients, especially those patients without a history of psychosis, which may reflect a diminished capacity to selectively attend to salient stimuli as opposed to impairments of inhibitory sensory processes. [source] In-patient comparison of immediate and conventional loaded implants in mandibular molar sites within 12 monthsCLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2008Güncü, M. Bar Abstract Objectives: The aim of this prospective clinical study was to evaluate the clinical outcomes of dental implants placed in the mandibular molar sites and immediately functionally restored compared with conventionally loaded controls in an in-patient study. Material and methods: Twenty-four dental implants were placed in 12 patients who had first molar loss bilaterally in the mandibular area. One site of the patient was determined as immediately loaded (IL) and the other side was conventionally loaded (CL). Resonance frequency analyses for implant stability measurements, radiographic examinations for marginal bone levels and peri-implant evaluations were performed during the clinical follow-up appointments within 12 months. Results: During the 12-month follow-up period, only one implant was lost in the IL group. The mean implant stability quotient values were 74.18±5.72 and 75.18±3.51 for Groups IL and CL at surgery, respectively, and the corresponding values were 75.36±5.88 and 75.64±4.84 at 1-year recall, respectively. The difference was not statistically significant between the two groups during the 12-month study period (P>0.05). When peri-implant parameters were evaluated, excellent peri-implant health was demonstrated during the 1-year observation period and all implants showed less than 1 mm of marginal bone resorption during the first year. Conclusions: In the present study, immediate functionally loading did not negatively affect implant stability, marginal bone levels and peri-implant health when compared with conventional loading of single-tooth implants. [source] Human ex vivo bone tissue strains around immediately loaded implants supporting maxillary overdenturesCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2005vanç Akça Abstract Purpose: To evaluate ex vivo bone tissue strains around maxillary implants supporting immediately loaded bar-retained overdentures. Material and methods: Ninety degree two-element rosette strain gauges were bonded on the labial bone of four ITI® dental implants placed in the maxillary anterior region of four completely edentulous maxilla of fresh human cadavers. The installation torque value (ITV) of each implant was measured by a custom-made torque wrench and resonance frequency analyses (RFAs) were undertaken. A bar-retained overdenture was fabricated for each cadaver, and two miniature load cells were integrated in the first molar region of the overdentures for controlled loading experiments. Strain measurements were performed at a sample rate of 10 kHz and under a maximum load of 100 N, simultaneously monitored from a computer connected to a data acquisition system. Finally, removal torque values (RTVs) of the implants were measured. Results: RFA values did not mirror ITVs, while RTVs of implants were slightly lower than the ITVs. Any correlation could not be obtained between RFA values and ITVs or RTVs. Maximum strains around loaded implants ranged between ,100 and ,550 ,, under 25,100 N. The axial and lateral strain values of posterior implants of both sides were higher than those of anterior implants under all loads (P<0.05). Conclusion: Because occlusal forces in humans tend to decrease because of age-related factors, maximum strains around immediately loaded implants supporting maxillary overdentures fall within physiologic levels. Résumé Le but de cette étude a été d'évaluer les tensions du tissu osseux ex vivo autour d'implants maxillaires portant des prothèses amovibles retenues sur une barre placée immédiatement après l'insertion des implants. Deux jauges de force en rosette à 90° ont été attachées au côté lingual de l'os de quatre implants dentaires ITI® placés dans la région antérieure du maxillaire de quatre cadavres humains frais aux maxillaires édentées. La valeur du couple de torsion lors de l'installation (ITV) de chaque implant a été mesurée par un couple fabriqué et des analyses de fréquence de résonnance (RFA) ont été faites. Une prothèse retenue par une barre a été fabriquée pour chaque cadavre et deux cellules de charge miniatures ont été intégrées dans la région de la première molaire de ces prothèses pour les expériences de charge contrôlées. Les mesures de force ont été effectuées à un taux d'échantillonnage de 10 kHz et sous une charge maximale de 100 N, suivies simultanément par un ordinateur connectéà un système d'acquisition de données. Finalement les valeurs des couples de torsion à l'enlèvement (RTV) des implants ont été mesurées. Les valeurs RFA n'étaient pas en ligne avec les ITV tandis que les RTV des implants étaient légèrement inférieurs aux ITV. Aucune corrélation n'a pûêtre établie entre les valeurs RFA et ITV ou RTV. Les forces maximales autour des implants chargés s'étalaient de ,100 ,e à,550 ,e sous 25 N à 100 N. Les valeurs des forces axiales et latérales des implants postérieurs des deux côtés étaient supérieures à celles des implants antérieurs sous toutes les charges (P<0.05). Zusammenfassung Ziel: Es war das Ziel dieser Arbeit, an bis vor kurzem vitalen Knochengewebe Spannungen um Oberkieferimplantate zu untersuchen, welche sofortbelastete und stegverankerte Hybridprothesen tragen. Material und Methoden: Auf den labialen Knochen von vier ITI-Implantaten in der vorderen Region des zahnlosen Oberkiefers von vier frisch verstorbenen Menschen klebte man Dehnmessinstrumente an. Man mass den Wert der Eindrehkraft (ITV) jedes einzelnen Implantates mit einem handelsblichen Drehmomentschlssel und fhrte eine Resonanzfrequenzanalyse (RFA) durch. Man stellte fr jede Leiche eine stegverankerte Hybridprothese her und man baute in der Region der ersten Molaren zwei kleine Messgerte ein, die kontrollierte Belastungsexperimente erlaubten. Dehnmessungen fhrte man mit einer Frequenz von 10 kHz und einer maximalen Belastung von 100 N durch, simultan aufgezeichnet von einem mit dem Messsystem verbundenen Komputer. Schliesslich mass man auch die Krfte, die es brauchte um die Implantate wieder auszudrehen (RTV). Resultate: Die RFA wiederspiegelte die ITV-Werte nicht, whrenddem die RTV-Werte der Implantate geringfgig tiefer waren als die ITV-Werte. Man konnte weder zwischen der RFA, den ITV-Werten oder den RTV-Werten eine Korrelation herstellen. Die maximalen Dehnungen um die Implantate erreichte Werte zwischen ,100 E und ,550 E bei einer Belastung zwischen 25 N und 100 N. Die axialen und lateralen Dehnkrfte bei posterioren Implantaten waren unter smtlichen getesteten Belastungen beidseits grsser als diejenigen der anterioren Implantate (P<0.05). Resumen Propósito: Evaluar las tensiones del tejido óseo ex vivo alrededor de implantes maxilares soportando sobredentaduras retenidas por barras con carga inmediata. Material y Métodos: Se pegaron dos indicadores de tensión de roseta de dos elementos de 90° en el hueso labial de cuatro implantes dentales ITI® colocados en la región maxilar anterior de cuatro maxilares completamente edéntulos de cadáveres humanos frescos. Se midió el valor del torque de instalación (ITV) de cada implante por medio de una chicharra de torque hecha a medida y se llevó a cabo análisis de frecuencia de resonancia (RFA). Se fabricó una sobredentadura retenida por barras para cada cadáver y se integraron dos células miniatura de carga en la región del primer molar de las sobredentaduras para los experimentos de carga controlada. Se llevaron a cabo mediciones de la tensión a un índice de muestra de 10 kHz y bajo una carga máxima de 100 N, simultáneamente monitorizada desde un ordenador conectado a sistema de adquisición de datos. Finalmente, se midieron los valores del torque de remoción (RTV) de los implantes. Resultados: Los valores de RFA no se reflejaron en los ITVs, mientras que los RTVs de los implantes fueron ligeramente más bajos que los ITVs. No se pudieron obtener correlaciones entre los valores de RFA y los ITVs o RTVE. Las tensiones máximas alrededor de los implantes cargados variaron entre ,100 ,, y ,550 ,, bajo 25 N a 100 N. Los valores de las tensiones axiales y laterales de los implantes posteriores de ambos lados fueron mayores que aquellos implantes anteriores bajo todas las cargas (P<0.05). [source] Suppression of background gradients in (B0 gradient-based) NMR diffusion experimentsCONCEPTS IN MAGNETIC RESONANCE, Issue 5 2007Gang Zheng Abstract Artifacts arising from background gradients are very common in NMR diffusion (i.e., PGSE) experiments involving B0 gradients because of the unavoidable magnetic susceptibility differences and B0 inhomogeneity within and around the sample. This article presents the general methodology to develop PGSE sequences with background gradient suppression. Most of the available methods which can be used for the suppression of the effects of background gradients are discussed. And two newly developed methods are presented in detail: frequency analysis of spin-dephasing, which assumes the artifacts due to background gradients come from the resonance between the spin-dephasing caused by applied gradients and background gradients, and asymmetric bipolar stimulated-echo-based PGSE, which can suppress the effects of nonconstant background gradients. © 2007 Wiley Periodicals, Inc.Concepts Magn Reson Part A 30A: 261,277, 2007. [source] Dynamic Changes of Ictal High-Frequency Oscillations in Neocortical Epilepsy: Using Multiple Band Frequency AnalysisEPILEPSIA, Issue 2 2007Ayako Ochi Summary:,Purpose: To characterize the spatial and temporal course of ictal high-frequency oscillations (HFOs) recorded by subdural EEG in children with intractable neocortical epilepsy. Methods: We retrospectively studied nine children (four girls, five boys; 4,17 yr) who presented with intractable extrahippocampal localization-related epilepsy and who underwent extraoperative video subdural EEG (1000 Hz sampling rate) and cortical resection. We performed multiple band frequency analysis (MBFA) to evaluate the frequency, time course, and distribution of ictal HFOs. We compared ictal HFO changes before and after clinical onset and postsurgical seizure outcomes. Results: Seventy-eight of 79 seizures showed HFOs. We observed wide-band HFOs (,250Hz, ,120 electrodes) in six patients either with partial seizures alone (three patients) or with epileptic spasms (three patients). Three patients with partial seizures that secondarily generalized had wide-band HFOs (,170 Hz) before clinical onset and sustained narrow-band HFOs (60,164 Hz) with electrodecremental events after clinical onset (,28 electrodes). In four postoperatively seizure-free patients, more electrodes recorded higher-frequency HFOs inside the resection area than outside before and after clinical seizure onset. In five patients with residual seizures, electrodes recorded more HFOs that were of higher or equal frequency outside the surgical area than inside after clinical onset. Conclusion: For partial seizures alone and epileptic spasms, more electrodes recorded only wide-band HFOs; for partial seizures that secondarily generalized, fewer electrodes recorded wide-band HFOs, but in these seizures electrodes also recorded subsequent sustained narrow-band ictal HFOs. Resection of those brain regions having electrodes with ictal, higher HFOs resulted in postsurgical seizure-free outcomes. [source] The role of valence in the perception of agency and communionEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 7 2008Caterina Suitner Social judgments necessarily carry evaluative connotations that may mask other dimensions of interest. With reference to bi-dimensional models of stereotype content, we analyzed the role of valence in the study of agency and communion. Because agency and communion are both positively evaluated dimensions, we hypothesize that valence may function as a "third variable" that obscures their obverse relation. In Study 1, investigating people's lay understanding of agency and communion, ratings of 130 adjectives revealed a positive correlation between the two dimensions, unless valence was controlled for, in which case the correlation became negative. In Study 2, exemplifying the role of valence in the case of gender stereotyping, a word frequency analysis of Italian language revealed that more agentic traits were more likely to occur in masculine and more communal traits in feminine form, but again this link emerged only after controlling for valence. This research highlights the importance of controlling for valence when studying the distinct roles of agency and communion in social perception. Copyright © 2008 John Wiley & Sons, Ltd. [source] Population size, weight distribution and food in a persistent population of the rare medicinal leech, Hirudo medicinalisFRESHWATER BIOLOGY, Issue 8 2008J. M. ELLIOTT Summary 1. It is important for species recovery and conservation management projects to know the minimum viable population size for rare and endangered species, such as the medicinal leech, Hirudo medicinalis. Therefore, using a catch-removal method, this study estimated every two years (1986, 1988, 1990, 1992) the total number of medicinal leeches in a tarn in the English Lake District, and the number of mature adults in the population. 2. Four samples were taken each year in June and July, when water temperatures exceeded 20 °C. Population size was estimated both by maximum likelihood and regression methods. All leeches were weighed alive and size groups were separated by polymodal frequency analysis. A small sample of the blood meal in each leech gut was taken before the leeches were returned to the tarn, and was used to estimate the proportion of mammalian and non-mammalian blood in the meals. 3. Both methods of estimation produced similar values, increasing confidence in the population estimates. Values for the total population in June and July varied among years from 248 to 288, the maximum value being only 16% higher than the minimum. Values for the number of mature leeches varied from 48 to 58 (19,20% of the total population), and this was an estimate of the effective population size. 4. There were four size groups. The largest mature leeches (live weight >5 g) in group IV formed only 1% of the population, and the smallest (0.02,0.5 g) in group I 14,17%. Most leeches were in two overlapping groups of immature (64,67% of population) and mature (18%) leeches with size ranges of 0.4,3.4 g and 2.5,5 g respectively. The percentage of leeches in each size group was very consistent among years. Blood meals were found in 38,44% of the leeches in group I, 45,50% in group II, 70,75% in group III, and 100% in group IV, but mammalian blood was present only in larger mature leeches (>3.5 g). 5. Medicinal leeches were first detected in the tarn in 1980 and are still present in 2007, so the population has persisted for at least 27 years. Compared with minimum viable population sizes for other species, including many endangered species, values for this medicinal leech population are extremely low, but may be typical of some rare freshwater invertebrates in isolated habitats. [source] Neural correlates of consolidation in working memoryHUMAN BRAIN MAPPING, Issue 3 2007Nelly Mainy Abstract Many of our daily activities rely on a brain system called working memory, which implements our ability to encode information for short-term maintenance, possible manipulation, and retrieval. A recent intracranial study of patients performing a paradigmatic working memory task revealed that the maintenance of information involves a distributed network of oscillations in the gamma band (>40 Hz). Using a similar task, we focused on the encoding stage and targeted a process referred to as short-term consolidation, which corresponds to the encoding of novel items in working memory. The paradigm was designed to manipulate the subjects' intention to encode: series of 10 letters were presented, among which only five had to be remembered, as indicated by visual cues preceding or following each letter. During this task we recorded the intracerebral EEG of nine epileptic patients implanted in mesiotemporal structures, perisylvian regions, and prefrontal areas and used time,frequency analysis to search for neural activities simultaneous with the encoding of the letters into working memory. We found such activities in the form of increases of gamma band activity in a set of regions associated with the phonological loop, including the Broca area and the auditory cortex, and in the prefrontal cortex, the pre- and postcentral gyri, the hippocampus, and the fusiform gyrus. Hum Brain Mapp, 2007. © 2006 Wiley-Liss, Inc. [source] Development of design flood hydrographs using probability density functionsHYDROLOGICAL PROCESSES, Issue 4 2010Niranjan Pramanik Abstract Probability density functions (PDFs) are used to fit the shape of hydrographs and have been popularly used for the development of synthetic unit hydrographs by many hydrologists. Nevertheless, modelling the shapes of continuous stream flow hydrographs, which are probabilistic in nature, is rare. In the present study, a novel approach was followed to model the shape of stream flow hydrographs using PDF and subsequently to develop design flood hydrographs for various return periods. Four continuous PDFs, namely, two parameter Beta, Weibull, Gamma and Lognormal, were employed to fit the shape of the hydrographs of 22 years at a site of Brahmani River in eastern India. The shapes of the observed and PDF fitted hydrographs were compared and root mean square errors, error of peak discharge (EQP) and error of time to peak (ETP) were computed. The best-fitted shape and scale parameters of all PDFs were subjected to frequency analysis and the quartiles corresponding to 20-, 50-, 100- and 200-year were estimated. The estimated parameters of each return period were used to develop the flood hydrographs for 20-, 50-, 100- and 200-year return periods. The peak discharges of the developed design flood hydrographs were compared with the design discharges estimated from the frequency analysis of 22 years of annual peak discharges at that site. Lognormal-produced peak discharge was very close to the estimated design discharge in case of 20-year flood hydrograph. On the other hand, peak discharge obtained using the Weibull PDF had close agreement with the estimated design discharge obtained from frequency analysis in case of 50-, 100- and 200-year return periods. The ranking of the PDFs based on estimation of peak of design flood hydrograph for 50-, 100- and 200-year return periods was found to have the following order: Weibull > Beta > Lognormal > Gamma. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||