Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Statistical Distributions”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76Linked to original sources
PubMed2003

Atmospheric lead concentration distribution in Northern Taiwan.

Atmospheric lead concentrations were measured randomly, approximately once per week, at five traffic sites in northern Taiwan from September 1994 to May 1995. Three types of theoretical distributions, lognormal, Weibull and gamma were selected to fit the frequency distribution of the measured lead concentration. Four goodness-of-fit criteria were used to judge which theoretical distribution is the most appropriate to represent the frequency distributions of atmospheric lead. The results show that atmospheric lead concentrations in total suspended particulates fit the lognormal distribution reasonably well in northern Taiwan. The intervals of fitted theoretical cumulative frequency distributions (CFDs) can successfully contain the measured data when the population mean is estimated with a 95% confidence interval. In addition, atmospheric lead concentration exceeding a critical concentration is also predicted from the fitted theoretical CFDs.

Air Pollutants↗
PubMed2002

Factors determining the reliable description of global tumbling parameters in solution NMR.

An accurate description of global tumbling of a protein is essential for correct analysis and interpretation of internal dynamics and thermodynamics. The accurate fitting of global tumbling parameters is affected by the number of experimental relaxation data points available for analysis, the distribution of data points over the domain of the function describing the tumbling, the measurement error associated with the data, the error associated with use of an approximate functional form, and errors in the protein structure. We present an analysis of the influence of these factors on the error in global tumbling parameters and the corresponding error in the calculated T(1)/T(2) values. We find that reduction of experimental and approximation error can compensate for a less-than-ideal quantity or distribution of data points, and that accurate parameters can be obtained for proteins with highly anisotropic distributions of bond vectors, as illustrated using the helical bundle protein G-CSF. This indicates that proteins with anisotropic distributions, such as the helical bundle class of proteins, should not summarily be excluded when selecting proteins for dynamic and thermodynamic analyses of (15)N backbone relaxation measurements.

Anisotropy↗
PubMed2001

Using the overdispersed exponential family to estimate the distribution of usual daily intakes of people aged between 18 and 28 in Taiwan.

Assessment of usual dietary intake of a population is essential to understand the nutrition status of the population. Methods like 24-hour dietary recall and food records are commonly used for this task. However, within-individual variation exists in the food record data. Methods considering measurement errors have been used to evaluate the association between nutrient intakes and diseases. Few have been devoted to estimating the distribution of usual daily intakes. This paper proposes applying the formulation of the overdispersed exponential family to estimate the distribution of usual nutrient intake and applies the adjustments developed by Liu to reduce the variance of the distribution. The proposed method has the advantages of working on the original scale of data and implementation convenience. The adjustment of the variance is carried out by dividing the variance into within-individual variance and among-individual variance. The adjusted variance, then, is used to estimate the distribution of the usual daily intake. Sampling weights are considered in all the steps, except the estimation of the ratio of within to among variance. The data for this study are from the Nutritional and Health Survey in Taiwan conducted between 1993 and 1996 (NAHSIT, 1993-1996). An independent external set of data for people aged between 18 and 28 years (49 males and 20 females) is used to estimate the ratio of within to among individual variance. Due to the availability of data in estimating the ratio of within to among individual variance, 430 males and 422 females in the NAHSIT sample are used to estimate the distribution of usual daily intakes for people aged between 18 and 28 in Taiwan. The distribution also allows us to estimate the proportion of people who do not meet the recommended daily nutrient allowance (RDNA). The results show that the intakes of calcium and vitamin E of this group of people fall far below RDNA.

Adolescent↗
PubMed2005

A genetic code Boolean structure. II. The genetic information system as a Boolean information system.

A Boolean structure of the genetic code where Boolean deductions have biological and physicochemical meanings was discussed in a previous paper. Now, from these Boolean deductions we propose to define the value of amino acid information in order to consider the genetic information system as a communication system and to introduce the semantic content of information ignored by the conventional information theory. In this proposal, the value of amino acid information is proportional to the molecular weight of amino acids with a proportional constant of about 1.96 x 10(25) bits per kg. In addition to this, for the experimental estimations of the minimum energy dissipation in genetic logic operations, we present two postulates: (1) the energy Ei (i=1,2,...,20) of amino acids in the messages conveyed by proteins is proportional to the value of information, and (2) amino acids are distributed according to their energy Ei so the amino acid population in proteins follows a Boltzmann distribution. Specifically, in the genetic message carried by the DNA from the genomes of living organisms, we found that the minimum energy dissipation in genetic logic operations was close to kTLn(2) joules per bit.

Algorithms↗
PubMed1997

[The application of artificial neural network based on ambiguous function to heart sound classification].

In this study the artificial neural network was applied to heart sound classification. The network input data are ambiguous function, hence the crossterm problem of Wigner distribution is avoided. The simulation result shows that this is an effective technique. A suboptimal network model was proposed by many times of training and checking. The main factors related to network property were also discussed.

Aerospace Medicine↗
PubMed2004

Extreme value distributions of mixing two sequences with the same MDA.

Suppose [(i), i>or=1] and [Y(i), i>or=1] are two independent sequences with distribution functions F(X)(x) and F(Y)(x), respectively. Z(i,n) is the combination of X(i) and Y(i) with a probability p(n) for each i with 1<or=i<or=n. The extreme value distribution G(Z)(x) of this particular triangular array of the i.i.d. random variables Z(1,n), Z(2,n), ..., Z(n,n) is discussed. We found a new form of the extreme value distributions i) Phi(alpha(1))(A)(x)Phi(alpha(2))(x) and ii) Psi(alpha(1))(A)(x)Psi(alpha(2))(x) (alpha(1)<alpha(2)), which are not max-stable. It occurs if F(X) and F(Y) belong to the same MDA(Phi) or MDA(Psi).

Algorithms↗
PubMed2005

Temporal patterns of ventricular tachyarrhythmia recurrences follow a Weibull distribution.

UNLABELLED: Temporal patterns of ventricular tachyarrhythmias. INTRODUCTION: The objective of this study was to test whether the temporal patterns of ventricular tachyarrhythmia recurrences in patients with implantable cardioverter-defibrillator (ICD) follow a random or a clustered distribution. METHODS: Data analysis was conducted using the Medtronic (Minneapolis, MN) Gem DR database of 521 ICD patients. Patients with >or=3 sustained ventricular tachyarrhythmia detections that resulted in shock or antitachycardia pacing therapies were studied. The times between consecutively treated ICD detections for each patient were compared to an exponential model of random recurrences and a Weibull model for clustered recurrences. RESULTS: Seventy-one patients had >or=3VT episodes during follow-up of 131+/-86 days. A total of 2347 VT episodes were recorded (33+/-65 episodes/patient, median 10 episodes/patient). Patient age was 66+/-13 years, 78% male, 83% coronary artery disease, ejection fraction 31+/-11%, and 63% were taking antiarrhythmic drugs. By the Kolmogorov-Smirnov goodness-of-fit test, 38 of 71 patients (53.5%) showed that the pattern of detections differed from an exponential model (P<0.01 for each patient and the proportion of patients was similar to chance at P=0.65). In contrast, only 11 out of 71 patients (15.5%) showed that the pattern differed from the Weibull model (P<0.01 for each patient). The proportion of patients fitting the Weibull model was significantly greater than chance and was greater that the proportion fitting the exponential model (both P<0.001). The time interval between consecutive detections was less than 1 hour for 78% of all 2347 detections. The proportion of all 521 patients with >or=2, >or=3, >or= 4, >or=6, >or=8, and >or=10 ICD detections in a 24-hour period was 10.5%, 9.5%, 8.1%, 7.0%, 6.3%, and 5.2%, respectively. CONCLUSION: In most patients with >or=3 ICD detections, the recurrence pattern of treated ventricular tachyarrhythmia detections are clustered and can be described by a Weibull distribution. The proportion of patients with multiple detections in a 24-hour period declines in a linear fashion as the number of events in 24 hours increases from 2 to 10 events.

Aged↗
PubMed1999

Familiarity and pronounceability of nouns and names.

Ratings of familiarity and pronounceability were obtained from a random sample of 199 surnames (selected from over 80,000 entries in the Purdue University phone book) and 199 nouns (from the Kucera-Francis, 1967, word database). The distributions of ratings for nouns versus names are substantially different: Nouns were rated as more familiar and easier to pronounce than surnames. Frequency and familiarity were more closely related in the proper name pool than the word pool, although both correlations were modest. Ratings of familiarity and pronounceability were highly related for both groups. A production experiment showed that rated pronounceability was highly related to the time taken to produce a name. These data confirm the common belief that there are differences in the statistical and distributional properties of words as compared to proper names. The value of using frequency and the ratings of familiarity and pronounceability for predicting variations in actual pronunciations of words and names are discussed.

Adult↗
PubMed1987

[[Recent life expectancy of Koreans in Japan, 1980 and 1985]].

Two abridged life tables for Koreans living in Japan for 1980 and 1985 are constructed using vital statistics and census data. Among the findings are that "the expectations of life at birth of Korean males in Japan are 68.4 in 1980 and 70.3 in 1985, whereas those values of Korean females in Japan are 78.3 in 1980 and 78.7 in 1985, respectively. Recent life expectancies of Koreans in Japan have come to resemble those of Japanese more than those of Koreans in Korea." (SUMMARY IN ENG)

Asia↗
PubMedDate not supplied

Treatment of the collapsed femoral head by containment in Legg-Calve-Perthes disease.

One hundred ninety-seven patients with unilateral Legg-Calve-Perthes disease (LCPD) were followed-up to skeletal maturity. According to the lateral pillar classification, 142 hips were classified as group B and 55 hips as group C. Radiographs were evaluated for percent of collapse of the femoral head, Waldenstrom stage of disease at diagnosis, Mose sphericity, hinge abduction, lateral acetabular shape, and limb-length discrepancy. The hips were treated either by bedrest and traction in abduction (76), Petrie cast (21), abduction brace (74), or by pelvic or femoral osteotomy (26). One hundred twenty-five hips had less than a 2-mm difference in Mose sphericity at followup. According to the classification of Stulberg et al., 89 hips (45%) were class I, 57 (29%) were class II, 35 (18%) were class III, 12 (6%) were class IV, and 4 (2%) were class V. Analyses revealed statistically significant differences between group B versus group C with regard to the classifications of Stulberg et al. and Mose, lateral acetabular shape, age at onset, and limb-length discrepancy. There was no significant statistical difference with regard to the types of treatment. Containment treatment of a deformed femoral head from LCPD improves the sphericity of the hip and gives 63% satisfactory results according to the Mose classification and 74% satisfactory results according to the Stulberg et al. classification.

Age Distribution↗
PubMedDate not supplied

Disordered balance of IgA subclass production in the tonsils of some IgA nephropathy patients.

BACKGROUND: There are reports concerning the relationship between tonsillectomy and immunoglobulin A nephropathy (IgAN). Two reports on the biochemical analysis of over-produced IgA1 from IgAN patients were recently published. On the other hand, histochemical analysis of tonsillar tissue indicated the disordered balance in IgG and IgA producing cells and in the IgA subclass producing cells in IgAN patients. METHODS: IgA in tonsillar extracts and serum was separated into passed fraction (IgA2) and bound fraction (IgA1) by a jacalin-agarose column. Isoelectric focusing (IEF) analysis was carried out using an IPGphor instrument. The IgA content in each sample was analyzed by enzyme-linked immunosorbent assay (ELISA). RESULTS: The IgA1/IgA2 ratio of the tonsillar extracts from controls and IgAN patients was compared. The ratio distribution indicated statistically significant differences. The mean ratio for the control tonsil was 61/39. However, the ratio from eight out of thirty-two IgAN patients exhibited a higher value than the mean + 2SD (standard deviation) of the controls. Among them, three patients exhibited 92/8. Meanwhile, the ratios for serum by this method were close to the previously reported 89/11. There were no differences in the IgA1 IEF profile between the representative lowand high-IgA1 producing patients. CONCLUSIONS: This is the first report concerning IgA subclass distribution in tonsillar tissue. The ratio 61/39 for tonsillar IgA differ from the value (>90% of IgA1) in the previous histochemical report. The value is similar to the previous report for colostrum, whole saliva, jejunal fluid and bronchial fluid. The IgA1/IgA2 ratio distribution in the tonsillar extracts from the patients with chronic tonsillitis is significantly different from that of the IgAN patients.

Adolescent↗
PubMed2005

How to put probabilities on homographies.

We present a family of "normal" distributions over a matrix group together with a simple method for estimating its parameters. In particular, the mean of a set of elements can be calculated. The approach is applied to planar projective homographies, showing that using priors defined in this way improves object recognition.

Algorithms↗
PubMed2000

Spatio-temporal interaction with disease mapping.

Markov chain Monte Carlo methods are used to estimate mortality rates under a Bayesian hierarchical model. Spatial correlations are introduced to examine spatial effects relative to both regional and regional changes over time by groups. A special feature of the models is the inclusion of longitudinal variables which will describe temporal trends in mortality or incidences for different population groups. Disease maps are used to illustrate the role of different parameters in the model and pinpointing areas of interesting patterns. The methods are demonstrated by male cancer mortality data from the state of Missouri during 1973-1992. Of special interest will be the geographic variations in the trend of lung cancer mortality over the recent past. Marginal posterior distributions are used to examine effects due to spatial correlations and age difference in temporal trends. Numerical results from the Missouri data show that although spatial correlations exist, they do not have a large effect on the estimated mortality rates.

Aged↗
PubMed2005

Changes in shape and location of BMI distributions of Swedish children.

AIMS: One aim was to disentangle how the shape and location of the BMI distribution changed among Swedish children over a 12 y period. Another aim was to identify the age during childhood when changes occurred or became manifest. METHODS: Two population-based cohorts-2,591 children from Stockholm born 1985-1987 and 3,650 from Gothenburg born 1973-1975-were compared with respect to BMI distributions from 2 to 15 y of age. RESULTS: Differences between the BMI distributions of the two cohorts were present from 5-6 y of age. From age 7, the children born in 1985-1987 and belonging to the upper parts of the BMI distribution, e.g. those above the 90th or 95th BMI percentiles, had much higher BMI mean values compared to their counterparts born 12 y earlier. Comparisons with respect to the 5th, 10th, 25th, 50th, 75th, 90th and 95th BMI percentiles showed that changes appeared above the 25th percentile and became increasingly pronounced in the upper parts of the BMI distributions. CONCLUSION: School-aged children in the rightmost parts of the BMI distributions may be more susceptible to "obesogenic" environmental exposures than those in the middle or leftmost parts. The results support the suggestion that the period of BMI rebound is critical for the development of obesity.

Adolescent↗
PubMed2002

Focal segmental glomerulosclerosis in malignant hypertension.

OBJECTIVE: Focal segmental glomerulosclerosis (FSG) may occur in primary malignant hypertension (MHT) either as a result of glomerular hyperfiltration or fibrinoid necrosis (FN), and may contribute to renal dysfunction. To determine the frequency of occurrence and distribution of FSG in primary MHT we studied renal biopsy specimens from 38 black Africans--30 postmortem and 8 needle-biopsy specimens. SUBJECTS: There were 31 male subjects and 7 female, with a mean age of 46 (+/- 7) years. RESULTS: Mean blood pressure (BP) was 206 +/- 15/137 +/- 9 mmHg, median 24-hour proteinuria (interquartile (IQ) range) was 5.1 g (3.3-6.5 g), median serum albumin 3.4 g (3.2-3.8 g) and median serum creatinine 540 mumol/l (425-752 mumol/l). Mucoid intimal proliferation was present in all the sections but FN was seen in 29 (76%). Glomerulosclerosis was present in all the sections, and was axially distributed in 7 (18%), segmentally in 22 (58%), and globally in 9 (24%). Median 24-hour proteinuria was 2.8 g (0.8-3.5 g IQ range), 5.6 g (1.7-8.1 g) and 3.4 g (2.6-4.0 g) respectively, and corresponding values of serum creatinine were 770 mumol/l (106-1,274 mumol/l IQ range), 522 mumol/l (248-991 mumol/l) and 1,230 mumol/l (920-1,558 mumol/l) respectively. CONCLUSION: The distribution of glomerulosclerosis did not appear to relate to proteinuria or serum creatinine, although cases with segmentally distributed glomerulosclerosis appeared to have the highest proteinuria, and those with global glomerulosclerosis appeared to have the highest serum creatinine levels. FSG therefore occurs prominently in primary MHT and may contribute to renal dysfunction.

Adult↗