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PubMed2005

[Application of wavelet transform to monthly runoff time serial analysis in Zagunao watershed, the upper Minjiang river].

Runoff is an important component of regional water resources, and its dynamics is to some extent an indicator of water resources dynamics in a region. To know the runoff dynamics and water resources in a region is essential for the sustainable utilization and planning of water resources, and for the research on hydrological response of vegetation change at watershed scale. To disclose the water resources dynamics in Upper Minjiang River, one of the large reaches of Yangze River in southwest China, this paper analyzed the runoff dynamic features of Zagunao watershed, an important watershed in Minjiang River basin. Multi-Resolution Analysis (MRA) and periodicity analysis were conducted with Dmey wavelet function on the monthly runoff data from 1962 to 2002 observed by Zagunao hydrological station, which provided a data-based approximation on the evolution of monthly runoff in Zagunao watershed. It was found that the runoff dynamics in Zagunao watershed was relatively stable during 1962 - 1978, despite that this period was just in correspondence with the term of intensive deforestation activities in Upper Minjiang River basin. It was also clear that the runoff in Zagunao watershed was increased from 1986 to 1997, which was inconsistent with the commonly accepted viewpoint that the runoff decreased with increasing vegetation cover in forest watershed. However, the increasing trend from 1986 - 1997 was consistent with the research results in Yichang by Wang Wensheng and with the global warming at global and continent scale, which meant that global climate change plays a big role in runoff dynamics in Upper Minjiang River. Periodicity analysis showed that the rich-short water periodicity at the scale of 10 years (120 months) and 5 years (60 months) was 3 and 7 times, respectively, which could provide invaluable information for the eco-hydrological function research of forest landscape in Minjiang river basin and the sustainable utilization of water resources. The results from the case study highlighted that sometimes, it was very necessary to consider the role of global climatic warming in disclosing the hydrological response of land use/cover change at watershed scale, otherwise, it would be difficult to explain some hydrological phenomena.

Algorithms↗
PubMed2006

Trends in alcohol-related mortality in Sweden 1969-2002: an age-period-cohort analysis.

AIM: To study the effects of age, period and cohorts on alcohol-related mortality trends in Sweden. DESIGN: The study comprises an age-period-cohort analysis. SETTING AND PARTICIPANTS: The analysis was based on all deaths in the Swedish population between 1969 and 2002. MEASUREMENTS: Data on alcohol-related deaths in Sweden from 1969 to 2002 excluding accidental injury and homicide were used. The analysis covered 43 021 deaths. FINDINGS: Time period and birth cohort both influenced alcohol-related mortality. Male cohorts born in the 1930-40s exhibited the highest alcohol-related mortality, while for females those born in the 1940-50s had the highest alcohol-related mortality. For both men and women, those born in the 1960-70s had the lowest age-adjusted alcohol-related mortality. High-risk cohorts were young or in early adulthood during the periods that alcohol became more available in Sweden. The low-risk cohorts of the 1960-70s were brought up during a period when society was concerned with increasing alcohol problems and more emphasis was placed on issuing alcohol awareness information in schools. CONCLUSIONS: Cohort effects were found suggesting that the link between alcohol consumption and non-accident alcohol-related mortality at the population level is dependent on other factors that may change over time. One such factor may be that restrictive alcohol policies have a greater effect on drinking in those who are younger at the time they are put into effect.

Adolescent↗
PubMed2002

Advanced detection of time trends in long-term cancer patient survival: experience from 50 years of cancer registration in Finland.

Timely monitoring of trends in long-term patient survival is an important task of cancer registries. Recently, a new method, denoted period analysis, has been proposed to enhance up-to-date monitoring of survival. The authors assessed the use of period analysis for advanced detection of time trends in long-term cancer patient survival based on data from the nationwide Finnish Cancer Registry by comparing estimates of 10-, 15-, and 20-year relative survival rates obtained by period analysis and by traditional (cohort) analysis of survival at various points of time between 1953 and 1997. Time trends are graphically displayed for the 15 most common forms of cancer. Long-term survival rates strongly improved over time for most forms of cancer. The slope and shape of trend curves obtained by period analysis are very similar to those obtained by traditional survival analysis. However, detection of progress in 10-, 15-, and 20-year survival rates of newly diagnosed patients could have been advanced by 5-10 years, 10-15 years, and 15-20 years, respectively, with the use of period analysis rather than traditional cohort survival analysis. The authors conclude that period analysis should be routinely used to advance detection of progress in long-term cancer patient survival.

Adolescent↗
PubMed1982

Period-peak analysis of the EEG with microprocessor applications.

This paper describes the development and evaluation of a period-peak algorithm for background analysis of the clinical electroencephalogram (EEG). The procedure is a time-domain method which is harmonious with manual interpretation of the EEG tracing. Conceptually the algorithm functions in 2 modes. Major counts are detected by successive baseline crossings in the period analysis mode. Presence of superimposed activity between major-counts induces a transition to the peak-detection mode. In this manner, period-peak analysis is capable of detecting the simultaneity of slow base-waves and relatively fast superimposed activity in the EEG. Preliminary studies have been conducted in which the analysis results of this procedure were compared to those of other EEG algorithms. In general, the period-peak algorithm offered less bias towards either end of the EEG spectrum. Subsequent to testing of a FORTRAN version, the period-peak algorithm has been implemented in assembly language on a dedicated microprocessor system for on-line analysis of EEG data.

Computers↗
PubMed1979

Period-amplitude analysis of EMG from slow and fast extensors of cat during locomotion and jumping.

A real-time period-amplitude analysis program for EMG involving the detection of events consisting of the period and amplitude difference between maxima and minima was used to study the activity patterns of fast and slow, hind and forelimb extensors during treadmill locomotion and jumping. Events were stored in a two-dimensional table providing an easily interpreted quantification of frequency and amplitude parameters of single EMG bursts which were characterized over a range of movements by the mean frequency and amplitude. Periods between zero crossings of the original signal were also stored. Both mean frequency and mean amplitude remained relatively steady for the slow extensors throughout the range of movements, while the fast extensors exhibited an increase in both mean frequency and mean amplitude during the same movements. The results show that fast extensors of the hind and forelimb follow the kinetic demands of the movement, while the activity pattern of the slow extensors is constant and independent of the movement kinetics. Slight discontinuities in these trends are discussed in their possible relation to the dynamics of msucle recruitment. Period-amplitude analysis provides a useful method of quantifying the raw EMG while retaining much of the original information of the signal.

Animals↗
PubMed1986

Circadian rhythms in Drosophila melanogaster: analysis of period as a function of gene dosage at the per (period) locus.

Mutations at the per (period) locus of Drosophila melanogaster affect the period of its circadian rhythms. An analysis of published data on strains having duplications and deletions of the per locus indicates that the period is a logarithmic function of the level of the per gene product. The analysis also indicates that period is relatively insensitive to the level of that gene product; a presumed 300% increase in the gene product level produces only a 4.6% decrease in the period. The period of a strain transformed with per+ DNA conforms to the same logarithmic relationship if the level of mRNA in the transformant, which is one-tenth that in the wild type, is considered equivalent to a gene dosage one-tenth the wild type dose of 2, or 0.2. The periods of strains having various doses of mutant per alleles which shorten (pers) or lengthen (per1) the period can be fitted to the same logarithmic function. The analysis may provide an explanation for the partial dominance of pers over per+ and the dominance of per+ over per1, since it suggests that the per1 gene product is nearly inactive while the pers gene product is more than 34 times as active as the wild type product. Analysis of periods of strains heterozygous at the per locus suggests that the per gene product may be a multimeric protein. Three possible roles for the per gene product in circadian rhythmicity are discussed, including a role in synchronizing rhythm-producing cells.

Alleles↗
PubMed1976

Qualitative and quantitative EEG in psychotic children.

The EEGs of hospitalized psychotic boys were analyzed quantitatively by means of visual evaluation, analog frequency analysis, and digital computer period analysis and were compared with those of age- and sex-matched normals. Visual evaluation of the records demonstrated that psychotic children have significantly more beta activity as well as fewer alpha bursts than normal controls. EEG analog frequency analysis showed that psychotic children have a greater percentage of total voltage in the 3-5 cps and 13-33 cps bands, while they show less voltage in the 6-12 cps bands as compared with normal controls. Digital computer period analysis demonstrated more slow, less alpha, and more fast activity, as well as a greater average frequency and frequency deviation in both the primary wave and first derivative measurements in psychotic children than normals, while normals showed a trend towards higher amplitude and amplitude variability. The similarity of the EEG differences between psychotic and normal children to those differences observed between adult chronic schizophrenics and normals, as well as to those between children of "high risk" for becoming schizophrenic and controls, suggests that the above described findings are characteristic for the pathophysiology of schizophrenia.

Adolescent↗
PubMed1988

On the age-period-cohort analysis of suicide rates.

Cohort analysis has become a popular method of examining national trends in suicide rates. Most of the studies investigating this phenomenon have reported a cohort effect to be present. Using a graphical approach, this paper places cohort analysis within the broader framework of age-period-cohort analysis. It is shown that published reports may have failed to identify cohort effects due to using only portions of the available data. With a simple mathematical model it is demonstrated that what appears to be a cohort effect may be a period effect, and conversely. It is recommended that suicide rates be examined for both period and cohort effects before conclusions are drawn regarding trends, and that the complete data set be used for this purpose.

Adolescent↗
PubMed2001

Searching for the time constant of neural pitch extraction.

Multichannel, auditory models have been repeatedly used to explain many aspects of human pitch perception. Among the most successful ones are models where pitch is estimated based on an analysis of periodicity in the simulated auditory-nerve firing. This periodicity analysis is typically implemented as a running autocorrelation, i.e., the autocorrelation is calculated within a temporal window which is shifted along the time axis. The window was suggested to have an exponential decay with time-constant estimates between 1.5 and 100 ms. The window length determines the minimal integration time of pitch extraction. The present experiments are designed to quantify the temporal window of pitch extraction using regular-interval noises (RINs). RINs were generated by concatenating equal-duration noise samples which produce a pitch corresponding to the reciprocal of the sample duration when the samples are identical (periodic noise). When the samples are independent, the stimulus is Gaussian noise and produces no pitch. Using RIN stimuli where periodic portions interchange with aperiodic portions, it is shown that the temporal window of pitch extraction cannot be modeled using a single time constant but that the size of the temporal window depends on the pitch itself.

Adult↗
PubMed1996

Descriptive multidimensional statistical methods for analysing signals in a multifactorial biomedical database.

A methodology is presented to analyse multidimensional signals from several recording periods resulting from an experimental study on human or other living systems. The methodology is divided into two stages: intra-period analysis and inter-period analysis. The purpose of the first stage is to highlight general trends in multidimensional signal changes and the more informative components of the signals. The purpose of the second stage is to assess the influence of environmental or individual difference factors on a given signal component that appears to be discriminant in the first stage. To take into account the multivariable state of the system and the multi-observational aspect, a multidimensional descriptive statistical approach is used. The methods are correspondence analysis and hierarchical clustering. They are illustrated through an occupational medicine application from a study of sedentary posture.

Biomedical Engineering↗
PubMed2005

Inferring yeast cell cycle regulators and interactions using transcription factor activities.

BACKGROUND: Since transcription factors are often regulated at the post-transcriptional level, their activities, rather than expression levels may provide valuable information for investigating functions and their interactions. The recently developed Network Component Analysis (NCA) and its generalized form (gNCA) provide a robust framework for deducing the transcription factor activities (TFAs) from various types of DNA microarray data and transcription factor-gene connectivity. The goal of this work is to demonstrate the utility of TFAs in inferring transcription factor functions and interactions in Saccharomyces cerevisiae cell cycle regulation. RESULTS: Using gNCA, we determined 74 TFAs from both wild type and fkh1 fkh2 deletion mutant microarray data encompassing 1529 ORFs. We hypothesized that transcription factors participating in the cell cycle regulation exhibit cyclic activity profiles. This hypothesis was supported by the TFA profiles of known cell cycle factors and was used as a basis to uncover other potential cell cycle factors. By combining the results from both cluster analysis and periodicity analysis, we recovered nearly 90% of the known cell cycle regulators, and identified 5 putative cell cycle-related transcription factors (Dal81, Hap2, Hir2, Mss11, and Rlm1). In addition, by analyzing expression data from transcription factor knockout strains, we determined 3 verified (Ace2, Ndd1, and Swi5) and 4 putative interaction partners (Cha4, Hap2, Fhl1, and Rts2) of the forkhead transcription factors. Sensitivity of TFAs to connectivity errors was determined to provide confidence level of these predictions. CONCLUSION: By subjecting TFA profiles to analyses based upon physiological signatures we were able to identify cell cycle related transcription factors consistent with current literature, transcription factors with potential cell cycle dependent roles, and interactions between transcription factors.

Cell Cycle↗
PubMed1997

[Studies on polysaccharide from Akebia trifoliate (I)].

Crude polysaccharide ATB was extracted from the stems of Akebia trifoliate with 5% NaOH. It was then subjected to DEAE-Cellulose column chromatography and purified by Sephadex G-200 chromatography. Finally, a pure polysaccharide ATBB-2 was obtained. The molecular weight of ATBB-2 was estimated to be 2.3 x 10(5). By total acid hydrolysis, the analytical results indicated that ATBB-2 is composed of Rha, Ara, Xyl, Gal, Glc and GalA in a molar ratio of 1.22:1.00:1.10:0.85:0.24:0.82. Methylation analysis, periodate oxidation analysis, Smith degradation, partial acid hydrolysis, 1H and 13CNMR showed that ATBB-2 is a highly branched molecule without a main chain.

Drugs, Chinese Herbal↗
PubMedDate not supplied

[Modeling of auditory mechanisms of pitch perception].

A hypothesis of two subordinately interconnected pitch perception systems is put forward and described. The leading system is responsible for the analysis of periodical sequences of spikes along audioneurons whose generation moments are synchronized by the acting sound oscillations. This system allows measuring of any periodical sound--simple or complex--including the residual sound. However, the system of periodicity analysis does not ensure the experimentally determined precision of pitch change perception. It is shown that the signal distribution along the basilar membrane enables the activation of the second system which analyses the spatial--temporal image by means of a great number of well innervated internal receptor cells. This system functioning is characterized by small values of differential threshold pitches, since as a discriminatory characteristic a curt decline of the basilar membrane oscillation envelope is used which is formed after a prolonged sinusoidal sound.

Basilar Membrane↗
PubMed1987

Period-amplitude analysis of rat electroencephalogram: stage and diurnal variations and effects of suprachiasmatic nuclei lesions.

Period-amplitude analysis was used to measure the number of waves per unit time (wave incidence) and wave amplitude for 19 wavelength categories in the lateral cortical electroencephalogram (EEG) of five intact and four suprachiasmatic nuclei-lesioned rats during NREM sleep, waking, and paradoxical sleep (PS) over a period of 24 h. The analysis confirmed several parallels between rat electroencephalogram (EEG) and human EEG: The wave incidence and amplitude at all wavelengths are both practically indistinguishable between wake, PS, and NREM sleep onset. As NREM sleep EEG amplitude increases, slow wave incidence and amplitude increase. The incidence and amplitude of slow waves are greatest at the start of the diurnal NREM sleep period and lowest at its end. The pattern of diurnal variation of the NREM EEG may be modeled using two wave generators (sources of variation), one between 1 and 4 Hz, and the other between 5 and 16 Hz. The diurnal patterns for wake and PS are less clear, but both appear to require three generators, one below 3 Hz, one between 3.5 and 6 Hz, and one above 9 Hz. The EEG of suprachiasmatic nuclei-lesioned rats does not show any shift to longer wavelengths in NREM sleep. Wake, PS, and NREM EEG in these rats have a lower incidence and amplitude of slow waves than the corresponding stages in intact rats. One explanation is an inhibition of the slow wave generator as a result of the lesions.

Animals↗
PubMed1990

Temporal dimensions of the fertility transition: an age-period-cohort analysis of frontier fertility.

"This paper evaluates age, period, and cohort effects on marital fertility during onset of the Utah fertility transition (1880-1900). Computerized genealogies are used to derive age-period-cohort fertility rates for 49,842 once-married couples. Age, period and cohort effects on marital fertility are then estimated using Johnson's (1985) relational model. Declining marital fertility in Utah is shown to be explained by both lower fertility levels across periods and increasing age-specific limitation across cohorts. Direct cohort effects on fertility are insignificant. These results are consistent with prior research, and the view that fertility levels were adaptive (in part through birth spacing across ages) to immediate contexts of childbearing while age-specific fertility truncation increased across cohorts (in part through the more general diffusion of contraceptive innovations)."

Age Factors↗
PubMed2003

Secular trends in adolescent never smoking from 1990 to 1999 in California: an age-period-cohort analysis.

OBJECTIVES: We analyzed age, time period, and cohort effects on trends in adolescent cigarette smoking in California from 1990 to 1999. METHODS: Data from subjects aged 12 to 17 years (n = 26 536; 50.4% male) from the California Tobacco Survey and the California Youth Tobacco Survey were analyzed, and never smokers were used as the outcome measure. RESULTS: The proportion of never smokers increased from 60% for males and 66% for females in 1990 to around 70% for both sexes in 1999. Respondents were more likely to be never smokers if born in 1978 or later (i.e., aged 12 years or younger in 1990, when most tobacco control programs started in California). CONCLUSIONS: The statewide antitobacco programs prevented adolescents from starting to smoke, primarily through a cohort effect.

Adolescent↗