Two-Year College Mathematics Instructors' Conceptions of Variation

ERIC Educational Resources Information Center

Dabos, Monica Graciela Gandhini

2011-01-01

Statistics education researchers are urging teachers of statistics to help students develop a more sophisticated understanding of variation, since variation is the core of statistics. However, little research has been done into the conceptions of variation held by instructors of statistics. This is of particular importance at the community college…

Effect of fertility on secondary sex ratio and twinning rate in Sweden, 1749-1870.

PubMed

Fellman, Johan; Eriksson, Aldur W

2015-02-01

We analyzed the effect of total fertility rate (TFR) and crude birth rate (CBR) on the number of males per 100 females at birth, also called the secondary sex ratio (SR), and on the twinning rate (TWR). Earlier studies have noted regional variations in TWR and racial differences in the SR. Statistical analyses have shown that comparisons between SRs demand large data sets because random fluctuations in moderate data are marked. Consequently, reliable results presuppose national birth data. Here, we analyzed historical demographic data and their regional variations between counties in Sweden. We built spatial models for the TFR in 1860 and the CBR in 1751-1870, and as regressors we used geographical coordinates for the provincial capitals of the counties. For both variables, we obtained significant spatial variations, albeit of different patterns and power. The SR among the live-born in 1749-1869 and the TWR in 1751-1860 showed slight spatial variations. The influence of CBR and TFR on the SR and TWR was examined and statistical significant effects were found.

VARIATION OF KOC IN SURFACE SEDIMENTS FROM NARRAGANSETT BAY AND LONG ISLAND SOUND: ANALYSIS OF THE ROLE OF OTHER PARTICULATE CHARACTERISTICS

EPA Science Inventory

In the first part of this investigation, we examined whether differences in the Kocs of three nonpolar organic chemicals (Lindane, fluoranthene, tetrachlorinated biphenyl (PCB)) from five sites along the New England coast were statistically significant. Although no statistical di...

An Experimental Study of the Effect of Streamwise Vortices on Unsteady Turbulent Boundary-Layer Separation

DTIC Science & Technology

1988-12-09

Measurement of Second Order Statistics .... .............. .54 5.4 Measurement of Triple Products ...... ................. .58 5.6 Uncertainty Analysis...deterministic fluctuations, u/ 2 , were 25 times larger than the mean fluctuations, u𔃼, there were no significant variations in the mean statistical ...input signals, the three velocity components are cal- culated, Awn in ,i-;dual phase ensembles are collected for the appropriate statistical 3

Evaluation on the use of cerium in the NBL Titrimetric Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zebrowski, J.P.; Orlowicz, G.J.; Johnson, K.D.

An alternative to potassium dichromate as titrant in the New Brunswick Laboratory Titrimetric Method for uranium analysis was sought since chromium in the waste makes disposal difficult. Substitution of a ceric-based titrant was statistically evaluated. Analysis of the data indicated statistically equivalent precisions for the two methods, but a significant overall bias of +0.035% for the ceric titrant procedure. The cause of the bias was investigated, alterations to the procedure were made, and a second statistical study was performed. This second study revealed no statistically significant bias, nor any analyst-to-analyst variation in the ceric titration procedure. A statistically significant day-to-daymore » variation was detected, but this was physically small (0.01 5%) and was only detected because of the within-day precision of the method. The added mean and standard deviation of the %RD for a single measurement was found to be 0.031%. A comparison with quality control blind dichromate titration data again indicated similar overall precision. Effects of ten elements on the ceric titration`s performance was determined. Co, Ti, Cu, Ni, Na, Mg, Gd, Zn, Cd, and Cr in previous work at NBL these impurities did not interfere with the potassium dichromate titrant. This study indicated similar results for the ceric titrant, with the exception of Ti. All the elements (excluding Ti and Cr), caused no statistically significant bias in uranium measurements at levels of 10 mg impurity per 20-40 mg uranium. The presence of Ti was found to cause a bias of {minus}0.05%; this is attributed to the presence of sulfate ions, resulting in precipitation of titanium sulfate and occlusion of uranium. A negative bias of 0.012% was also statistically observed in the samples containing chromium impurities.« less

Generalized Hurst exponent estimates differentiate EEG signals of healthy and epileptic patients

NASA Astrophysics Data System (ADS)

Lahmiri, Salim

2018-01-01

The aim of our current study is to check whether multifractal patterns of the electroencephalographic (EEG) signals of normal and epileptic patients are statistically similar or different. In this regard, the generalized Hurst exponent (GHE) method is used for robust estimation of the multifractals in each type of EEG signals, and three powerful statistical tests are performed to check existence of differences between estimated GHEs from healthy control subjects and epileptic patients. The obtained results show that multifractals exist in both types of EEG signals. Particularly, it was found that the degree of fractal is more pronounced in short variations of normal EEG signals than in short variations of EEG signals with seizure free intervals. In contrary, it is more pronounced in long variations of EEG signals with seizure free intervals than in normal EEG signals. Importantly, both parametric and nonparametric statistical tests show strong evidence that estimated GHEs of normal EEG signals are statistically and significantly different from those with seizure free intervals. Therefore, GHEs can be efficiently used to distinguish between healthy and patients suffering from epilepsy.

Statistical analysis of aerosol species, trace gasses, and meteorology in Chicago.

PubMed

Binaku, Katrina; O'Brien, Timothy; Schmeling, Martina; Fosco, Tinamarie

2013-09-01

Both canonical correlation analysis (CCA) and principal component analysis (PCA) were applied to atmospheric aerosol and trace gas concentrations and meteorological data collected in Chicago during the summer months of 2002, 2003, and 2004. Concentrations of ammonium, calcium, nitrate, sulfate, and oxalate particulate matter, as well as, meteorological parameters temperature, wind speed, wind direction, and humidity were subjected to CCA and PCA. Ozone and nitrogen oxide mixing ratios were also included in the data set. The purpose of statistical analysis was to determine the extent of existing linear relationship(s), or lack thereof, between meteorological parameters and pollutant concentrations in addition to reducing dimensionality of the original data to determine sources of pollutants. In CCA, the first three canonical variate pairs derived were statistically significant at the 0.05 level. Canonical correlation between the first canonical variate pair was 0.821, while correlations of the second and third canonical variate pairs were 0.562 and 0.461, respectively. The first canonical variate pair indicated that increasing temperatures resulted in high ozone mixing ratios, while the second canonical variate pair showed wind speed and humidity's influence on local ammonium concentrations. No new information was uncovered in the third variate pair. Canonical loadings were also interpreted for information regarding relationships between data sets. Four principal components (PCs), expressing 77.0 % of original data variance, were derived in PCA. Interpretation of PCs suggested significant production and/or transport of secondary aerosols in the region (PC1). Furthermore, photochemical production of ozone and wind speed's influence on pollutants were expressed (PC2) along with overall measure of local meteorology (PC3). In summary, CCA and PCA results combined were successful in uncovering linear relationships between meteorology and air pollutants in Chicago and aided in determining possible pollutant sources.

Significance levels for studies with correlated test statistics.

PubMed

Shi, Jianxin; Levinson, Douglas F; Whittemore, Alice S

2008-07-01

When testing large numbers of null hypotheses, one needs to assess the evidence against the global null hypothesis that none of the hypotheses is false. Such evidence typically is based on the test statistic of the largest magnitude, whose statistical significance is evaluated by permuting the sample units to simulate its null distribution. Efron (2007) has noted that correlation among the test statistics can induce substantial interstudy variation in the shapes of their histograms, which may cause misleading tail counts. Here, we show that permutation-based estimates of the overall significance level also can be misleading when the test statistics are correlated. We propose that such estimates be conditioned on a simple measure of the spread of the observed histogram, and we provide a method for obtaining conditional significance levels. We justify this conditioning using the conditionality principle described by Cox and Hinkley (1974). Application of the method to gene expression data illustrates the circumstances when conditional significance levels are needed.

Lack of evidence for meteorological effects on infradian dynamics of testosterone

NASA Astrophysics Data System (ADS)

Celec, Peter; Smreková, Lucia; Ostatníková, Daniela; Čabajová, Zlata; Hodosy, Július; Kúdela, Matúš

2009-09-01

Climatic factors are known to influence the endocrine system. Previous studies have shown that circannual seasonal variations of testosterone might be partly explained by changes in air temperature. Whether infradian variations are affected by meteorological factors is unknown. To analyze possible effects of meteorological parameters on infradian variations of salivary testosterone levels in both sexes, daily salivary testosterone levels were measured during 1 month in 14 men and 17 women. A correlation analysis between hormonal levels and selected meteorological parameters was performed. The results indicate that high testosterone levels are loosely associated with cold, sunny and dry weather in both sexes. However, only the correlations between testosterone and air temperature (men) and actual cloudiness (women) were statistically significant ( p < 0,05). Although some correlations reached the level of statistical significance, the effects of selected meteorological parameters on salivary testosterone levels remain unclear. Further longer-term studies concentrating on air temperature, cloudiness and average relative humidity in relation to the sex hormone axis are needed.

Allelic Variation of Risk for Anxiety Symptoms Moderates the Relation Between Adolescent Safety Behaviors and Social Anxiety Symptoms

PubMed Central

Thomas, Sarah A.; Weeks, Justin W.; Dougherty, Lea R.; Lipton, Melanie F.; Daruwala, Samantha E.; Kline, Kathryn

2015-01-01

Social anxiety often develops in adolescence, and precedes the onset of depression and substance use disorders. The link between social anxiety and use of behaviors to minimize distress in social situations (i.e., safety behaviors) is strong and for some patients, this link poses difficulty for engaging in, and benefiting from, exposure-based treatment. Yet, little is known about whether individual differences may moderate links between social anxiety and safety behaviors, namely variations in genetic alleles germane to anxiety. We examined the relation between adolescent social anxiety and expressions of safety behaviors, and whether allelic variation for anxiety moderates this relation. Adolescents (n=75; ages 14–17) were recruited from two larger studies investigating measurement of family relationships or adolescent social anxiety. Adolescents completed self-report measures about social anxiety symptoms and use of safety behaviors. They also provided saliva samples to assess allelic variations for anxiety from two genetic polymorphisms (BDNF rs6265; TAQ1A rs1800497). Controlling for adolescent age and gender, we observed a significant interaction between social anxiety symptoms and allelic variation (β=0.37, t=2.41, p=.02). Specifically, adolescents carrying allelic variations for anxiety evidenced a statistically significant and relatively strong positive relation between social anxiety symptoms and safety behaviors (β=0.73), whereas adolescents not carrying allelic variation evidenced a statistically non-significant and relatively weak relation (β=0.22). These findings have important implications for treating adolescent social anxiety, in that we identified an individual difference variable that can be used to identify people who evidence a particularly strong link between use of safety behaviors and expressing social anxiety. PMID:26692635

Spatial Analysis of Hospital Incidence and in Hospital Mortality of Abdominal Aortic Aneurysms in Germany: Secondary Data Analysis of Nationwide Hospital Episode (DRG) Data.

PubMed

Kuehnl, Andreas; Salvermoser, Michael; Erk, Alexander; Trenner, Matthias; Schmid, Volker; Eckstein, Hans-Henning

2018-06-01

This study aimed to analyze the spatial distribution and regional variation of the hospital incidence and in hospital mortality of abdominal aortic aneurysms (AAA) in Germany. German DRG statistics (2011-2014) were analysed. Patients with ruptured AAA (rAAA, I71.3, treated or not) and patients with non-ruptured AAA (nrAAA, I71.4, treated by open or endovascular aneurysm repair) were included. Age, sex, and risk standardisation was done using standard statistical procedures. Regional variation was quantified using systematic component of variation. To analyse spatial auto-correlation and spatial pattern, global Moran's I and Getis-Ord Gi* were calculated. A total of 50,702 cases were included. Raw hospital incidence of AAA was 15.7 per 100,000 inhabitants (nrAAA 13.1; all rAAA 2.7; treated rAAA 1.6). The standardised hospital incidence of AAA ranged from 6.3 to 30.3 per 100,000. Systematic component of variation proportion was 96% in nrAAA and 55% in treated rAAA. Incidence rates of all AAA were significantly clustered with above average values in the northwestern parts of Germany and below average values in the south and eastern regions. Standardised mortality of nrAAA ranged from 1.7% to 4.3%, with that of treated rAAA ranging from 28% to 52%. Regional variation and spatial distribution of standardised mortality was not different from random. There was significant regional variation and clustering of the hospital incidence of AAA in Germany, with higher rates in the northwest and lower rates in the southeast. There was no significant variation in standardised (age/sex/risk) mortality between counties. Copyright © 2018. Published by Elsevier B.V.

Variations and inter-relationship in outcome from emergency admissions in England: a retrospective analysis of Hospital Episode Statistics from 2005-2010.

PubMed

Holt, Peter James Edward; Sinha, Sidhartha; Ozdemir, Baris Ata; Karthikesalingam, Alan; Poloniecki, Jan Dominik; Thompson, Matt Merfyn

2014-06-19

The quality of care delivered and clinical outcomes of care are of paramount importance. Wide variations in the outcome of emergency care have been suggested, but the scale of variation, and the way in which outcomes are inter-related are poorly defined and are critical to understand how best to improve services. This study quantifies the scale of variation in three outcomes for a contemporary cohort of patients undergoing emergency medical and surgical admissions. The way in which the outcomes of different diagnoses relate to each other is investigated. A retrospective study using the English Hospital Episode Statistics 2005-2010 with one-year follow-up for all patients with one of 20 of the commonest and highest-risk emergency medical or surgical conditions. The primary outcome was in-hospital all-cause risk-standardised mortality rate (in-RSMR). Secondary outcomes were 1-year all-cause risk-standardised mortality rate (1 yr-RSMR) and 28-day all-cause emergency readmission rate (RSRR). 2,406,709 adult patients underwent emergency medical or surgical admissions in the groups of interest. Clinically and statistically significant variations in outcome were observed between providers for all three outcomes (p < 0.001). For some diagnoses including heart failure, acute myocardial infarction, stroke and fractured neck of femur, more than 20% of hospitals lay above the upper 95% control limit and were statistical outliers. The risk-standardised outcomes within a given hospital for an individual diagnostic group were significantly associated with the aggregated outcome of the other clinical groups. Hospital-level risk-standardised outcomes for emergency admissions across a range of specialties vary considerably and cross traditional speciality boundaries. This suggests that global institutional infra-structure and processes of care influence outcomes. The implications are far reaching, both in terms of investigating performance at individual hospitals and in understanding how hospitals can learn from the best performers to improve outcomes.

Spatial and temporal patterns of locally-acquired dengue transmission in northern Queensland, Australia, 1993-2012.

PubMed

Naish, Suchithra; Dale, Pat; Mackenzie, John S; McBride, John; Mengersen, Kerrie; Tong, Shilu

2014-01-01

Dengue has been a major public health concern in Australia since it re-emerged in Queensland in 1992-1993. We explored spatio-temporal characteristics of locally-acquired dengue cases in northern tropical Queensland, Australia during the period 1993-2012. Locally-acquired notified cases of dengue were collected for northern tropical Queensland from 1993 to 2012. Descriptive spatial and temporal analyses were conducted using geographic information system tools and geostatistical techniques. 2,398 locally-acquired dengue cases were recorded in northern tropical Queensland during the study period. The areas affected by the dengue cases exhibited spatial and temporal variation over the study period. Notified cases of dengue occurred more frequently in autumn. Mapping of dengue by statistical local areas (census units) reveals the presence of substantial spatio-temporal variation over time and place. Statistically significant differences in dengue incidence rates among males and females (with more cases in females) (χ(2) = 15.17, d.f.  = 1, p<0.01). Differences were observed among age groups, but these were not statistically significant. There was a significant positive spatial autocorrelation of dengue incidence for the four sub-periods, with the Moran's I statistic ranging from 0.011 to 0.463 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the northern Queensland. Tropical areas are potential high-risk areas for mosquito-borne diseases such as dengue. This study demonstrated that the locally-acquired dengue cases have exhibited a spatial and temporal variation over the past twenty years in northern tropical Queensland, Australia. Therefore, this study provides an impetus for further investigation of clusters and risk factors in these high-risk areas.

Spatial and Temporal Patterns of Locally-Acquired Dengue Transmission in Northern Queensland, Australia, 1993–2012

PubMed Central

Naish, Suchithra; Dale, Pat; Mackenzie, John S.; McBride, John; Mengersen, Kerrie; Tong, Shilu

2014-01-01

Background Dengue has been a major public health concern in Australia since it re-emerged in Queensland in 1992–1993. We explored spatio-temporal characteristics of locally-acquired dengue cases in northern tropical Queensland, Australia during the period 1993–2012. Methods Locally-acquired notified cases of dengue were collected for northern tropical Queensland from 1993 to 2012. Descriptive spatial and temporal analyses were conducted using geographic information system tools and geostatistical techniques. Results 2,398 locally-acquired dengue cases were recorded in northern tropical Queensland during the study period. The areas affected by the dengue cases exhibited spatial and temporal variation over the study period. Notified cases of dengue occurred more frequently in autumn. Mapping of dengue by statistical local areas (census units) reveals the presence of substantial spatio-temporal variation over time and place. Statistically significant differences in dengue incidence rates among males and females (with more cases in females) (χ2 = 15.17, d.f. = 1, p<0.01). Differences were observed among age groups, but these were not statistically significant. There was a significant positive spatial autocorrelation of dengue incidence for the four sub-periods, with the Moran's I statistic ranging from 0.011 to 0.463 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the northern Queensland. Conclusions Tropical areas are potential high-risk areas for mosquito-borne diseases such as dengue. This study demonstrated that the locally-acquired dengue cases have exhibited a spatial and temporal variation over the past twenty years in northern tropical Queensland, Australia. Therefore, this study provides an impetus for further investigation of clusters and risk factors in these high-risk areas. PMID:24691549

Midweek Intensification of Rain in the U.S.: Does Air Pollution Invigorate Storms?

NASA Technical Reports Server (NTRS)

Bell, T. L.; Rosenfeld, D.; Hahnenberger, M.

2005-01-01

The effect of pollution on rainfall has been observed to depend both on the type of pollution and the precipitating environment. The climatological consequences of pollution for rainfall are uncertain. In some urban areas, pollution varies with the day of the week because of weekly variations in human activity, in effect providing a repeated experiment on the effects of pollution. Weekly variations in temperature, pressure, cloud characteristics, hails and lightning are observed in many areas. Observing a weekly cycle in rainfall statistics has proven to be more difficult, although there is some evidence for it. Here we examine rainfall statistics from the Tropical Rainfall Measuring Mission (TRMM) satellite over the southern U.S. and adjacent waters, and find that there is a distinct, statistically significant weekly cycle in summertime rainfall over the southeast U.S., as well as weekly variations in rainfall over the nearby Atlantic and the Gulf of Mexico. Rainfall over land peaks in the middle of the week, suggesting that summer rainfall on large scales may increase as pollution levels rise. Both rain statistics over land and what appear to be compensating effects over adjacent seas support the suggestion that air pollution invigorates convection and outflow aloft.

The color of sea level: Importance of spatial variations in spectral shape for assessing the significance of trends

NASA Astrophysics Data System (ADS)

Hughes, Chris W.; Williams, Simon D. P.

2010-10-01

We investigate spatial variations in the shape of the spectrum of sea level variability based on a homogeneously sampled 12 year gridded altimeter data set. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a fifth-order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times of what would be calculated assuming "white" noise and that the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes over this period.

A study of mortality patterns at a tyre factory 1951-1985: a reference statistic dilemma.

PubMed

Veys, C A

2004-08-01

The general and cancer mortalities of rubber workers at a large tyre factory were studied in an area of marked regional variation in death rates. Three quinquennial intakes of male rubber workers engaged between January 1946 and December 1960 formed a composite cohort of 6454 men to be followed up. Over 99% were successfully traced by December 1985. The cohort analysis used both national and local rates as reference statistics for several causes. Between 1951 and 1985, a national standardized mortality ratio (SMRN) of 101 for all causes (based on 2556 deaths) was noted, whereas the local standardized mortality ratio (SMRL) was only 79. For all cancers, the figures were 115 (SMRN) and 93 (SMRL), for stomach cancer they were 137 (SMRN) and 84 (SMRL), and for lung cancer they were 121 (SMRN) and 94 (SMRL). No outright excesses against the national norm were observed for other cancers except for larynx, brain and central nervous system and thyroid cancer and the leukaemias. Excesses were statistically significant for cancer of the gallbladder and the bile ducts, for silicotuberculosis (SMRN = 1000) and for the pneumoconioses (SMRN = 706). Deaths from cerebrovascular diseases, chronic bronchitis and emphysema showed statistically significant deficits using either norm. These results from a large factory cohort study of rubber workers, followed for over three decades, demonstrate the marked discrepancy that can result from using only one reference statistic in areas of significant variation in mortality patterns.

A time to be born: Variation in the hour of birth in a rural population of Northern Argentina.

PubMed

Chaney, Carlye; Goetz, Laura G; Valeggia, Claudia

2018-04-17

The present study aimed at investigating the timing of birth across the day in a rural population of indigenous and nonindigenous women in the province of Formosa, Argentina in order to explore the variation in patterns in a non-Western setting. This study utilized birth record data transcribed from delivery room records at a rural hospital in the province of Formosa, northern Argentina. The sample included data for Criollo, Wichí, and Toba/Qom women (n = 2421). Statistical analysis was conducted using directional statistics to identify a mean sample direction. Chi-square tests for homogeneity were also used to test for statistical significant differences between hours of the day. The mean sample direction was 81.04°, which equates to 5:24 AM when calculated as time on a 24-hr clock. Chi-squared analyses showed a statistically significant peak in births between 12:00 and 4:00 AM. Birth counts generally declined throughout the day until a statistically significant trough around 5:00 PM. This pattern may be associated with the circadian rhythms of hormone release, particularly melatonin, on a proximate level. At the ultimate level, giving birth in the early hours of the morning may have been selected to time births when the mother could benefit from the predator protection and support provided by her social group as well as increased mother-infant bonding from a more peaceful environment. © 2018 Wiley Periodicals, Inc.

Effects of wind direction on coarse and fine particulate matter concentrations in southeast Kansas.

PubMed

Guerra, Sergio A; Lane, Dennis D; Marotz, Glen A; Carter, Ray E; Hohl, Carrie M; Baldauf, Richard W

2006-11-01

Field data for coarse particulate matter ([PM] PM10) and fine particulate matter (PM2.5) were collected at selected sites in Southeast Kansas from March 1999 to October 2000, using portable MiniVol particulate samplers. The purpose was to assess the influence on air quality of four industrial facilities that burn hazardous waste in the area located in the communities of Chanute, Independence, Fredonia, and Coffeyville. Both spatial and temporal variation were observed in the data. Variation because of sampling site was found to be statistically significant for PM10 but not for PM2.5. PM10 concentrations were typically slightly higher at sites located within the four study communities than at background sites. Sampling sites were located north and south of the four targeted sources to provide upwind and downwind monitoring pairs. No statistically significant differences were found between upwind and downwind samples for either PM10 or PM2.5, indicating that the targeted sources did not contribute significantly to PM concentrations. Wind direction can frequently contribute to temporal variation in air pollutant concentrations and was investigated in this study. Sampling days were divided into four classifications: predominantly south winds, predominantly north winds, calm/variable winds, and winds from other directions. The effect of wind direction was found to be statistically significant for both PM10 and PM2.5. For both size ranges, PM concentrations were typically highest on days with predominantly south winds; days with calm/variable winds generally produced higher concentrations than did those with predominantly north winds or those with winds from "other" directions. The significant effect of wind direction suggests that regional sources may exert a large influence on PM concentrations in the area.

Relation of Chlorophyll Fluorescence Sensitive Reflectance Ratios to Carbon Flux Measurements of Montanne Grassland and Norway Spruce Forest Ecosystems in the Temperate Zone

PubMed Central

Ač, Alexander; Malenovský, Zbyněk; Urban, Otmar; Hanuš, Jan; Zitová, Martina; Navrátil, Martin; Vráblová, Martina; Olejníčková, Julie; Špunda, Vladimír; Marek, Michal

2012-01-01

We explored ability of reflectance vegetation indexes (VIs) related to chlorophyll fluorescence emission (R 686/R 630, R 740/R 800) and de-epoxidation state of xanthophyll cycle pigments (PRI, calculated as (R 531 − R 570)/(R 531 − R 570)) to track changes in the CO2 assimilation rate and Light Use Efficiency (LUE) in montane grassland and Norway spruce forest ecosystems, both at leaf and also canopy level. VIs were measured at two research plots using a ground-based high spatial/spectral resolution imaging spectroscopy technique. No significant relationship between VIs and leaf light-saturated CO2 assimilation (A MAX) was detected in instantaneous measurements of grassland under steady-state irradiance conditions. Once the temporal dimension and daily irradiance variation were included into the experimental setup, statistically significant changes in VIs related to tested physiological parameters were revealed. ΔPRI and Δ(R 686/R 630) of grassland plant leaves under dark-to-full sunlight transition in the scale of minutes were significantly related to A MAX (R 2 = 0.51). In the daily course, the variation of VIs measured in one-hour intervals correlated well with the variation of Gross Primary Production (GPP), Net Ecosystem Exchange (NEE), and LUE estimated via the eddy-covariance flux tower. Statistical results were weaker in the case of the grassland ecosystem, with the strongest statistical relation of the index R 686/R 630 with NEE and GPP. PMID:22701368

The influence of ENSO, PDO and PNA on secular rainfall variations in Hawai‘i

Treesearch

Abby G. Frazier; Oliver Elison Timm; Thomas W. Giambelluca; Henry F. Diaz

2017-01-01

Over the last century, significant declines in rainfall across the state of Hawai‘i have been observed, and it is unknown whether these declines are due to natural variations in climate, or manifestations of human-induced climate change. Here, a statistical analysis of the observed rainfall variability was applied as first step towards better understanding causes for...

Regional and Temporal Variation in Methamphetamine-Related Incidents: Applications of Spatial and Temporal Scan Statistics

PubMed Central

Sudakin, Daniel L.

2009-01-01

Introduction This investigation utilized spatial scan statistics, geographic information systems and multiple data sources to assess spatial clustering of statewide methamphetamine-related incidents. Temporal and spatial associations with regulatory interventions to reduce access to precursor chemicals (pseudoephedrine) were also explored. Methods Four statewide data sources were utilized including regional poison control center statistics, fatality incidents, methamphetamine laboratory seizures, and hazardous substance releases involving methamphetamine laboratories. Spatial clustering of methamphetamine incidents was assessed using SaTScan™. SaTScan™ was also utilized to assess space-time clustering of methamphetamine laboratory incidents, in relation to the enactment of regulations to reduce access to pseudoephedrine. Results Five counties with a significantly higher relative risk of methamphetamine-related incidents were identified. The county identified as the most likely cluster had a significantly elevated relative risk of methamphetamine laboratories (RR=11.5), hazardous substance releases (RR=8.3), and fatalities relating to methamphetamine (RR=1.4). A significant increase in relative risk of methamphetamine laboratory incidents was apparent in this same geographic area (RR=20.7) during the time period when regulations were enacted in 2004 and 2005, restricting access to pseudoephedrine. Subsequent to the enactment of these regulations, a significantly lower rate of incidents (RR 0.111, p=0.0001) was observed over a large geographic area of the state, including regions that previously had significantly higher rates. Conclusions Spatial and temporal scan statistics can be effectively applied to multiple data sources to assess regional variation in methamphetamine-related incidents, and explore the impact of preventive regulatory interventions. PMID:19225949

Seasonal variation in myocardial infarction is limited to patients with ST-elevations on admission.

PubMed

Leibowitz, David; Planer, David; Weiss, Teddy; Rott, David

2007-01-01

Previous studies have demonstrated seasonal variation in the incidence of acute myocardial infarction (AMI) with an increase in cases during the winter months. However, they did not assess whether ST-elevation MI (STEMI) and non-ST-elevation MI (NSTEMI) exhibit similar changes. The object of this study was to compare the seasonal variation of STEMI and NSTEMI. All patients who presented with AMI and underwent coronary angiography within seven days of admission were identified via the institutional database. STEMI diagnosis required admission ECG demonstrating ST elevation in at least two continguous leads. All AMIs not meeting criteria for STEMI were defined as NSTEMI. Patients were divided into monthly and seasonal groups based on the date of admission with MI. A total of 784 patients were included: 549 patients with STEMI and 235 with NSTEMI. When STEMI patients were analyzed by season, there were 170 patients (31%) in the winter months, a statistically significant difference of excess MI (p<0.005). When NSTEMI patients were analyzed, there were 62 patients (26%) in the winter with no statistically significant difference in the seasonal variation. Our findings suggest that the previously noted seasonal variation in the incidence of AMI is limited to patients presenting with STEMI, and that there are important physiological differences between STEMI and NSTEMI, the nature of which remains to be elucidated.

Human Genetic Variation and Yellow Fever Mortality during 19th Century U.S. Epidemics

PubMed Central

2014-01-01

ABSTRACT We calculated the incidence, mortality, and case fatality rates for Caucasians and non-Caucasians during 19th century yellow fever (YF) epidemics in the United States and determined statistical significance for differences in the rates in different populations. We evaluated nongenetic host factors, including socioeconomic, environmental, cultural, demographic, and acquired immunity status that could have influenced these differences. While differences in incidence rates were not significant between Caucasians and non-Caucasians, differences in mortality and case fatality rates were statistically significant for all epidemics tested (P < 0.01). Caucasians diagnosed with YF were 6.8 times more likely to succumb than non-Caucasians with the disease. No other major causes of death during the 19th century demonstrated a similar mortality skew toward Caucasians. Nongenetic host factors were examined and could not explain these large differences. We propose that the remarkably lower case mortality rates for individuals of non-Caucasian ancestry is the result of human genetic variation in loci encoding innate immune mediators. PMID:24895309

Divergent drivers of the spatial and temporal variations of cropland carbon transfer in Liaoning province, China.

PubMed

Zhu, Xian-Jin; Zhang, Han-Qi; Zhao, Tian-Hong; Li, Jian-Dong; Yin, Hong

2017-10-12

Spatial and temporal variations are important points of focus in ecological research. Analysing their differences improves our understanding on the variations of ecological phenomena. Using data from the Liaoning Statistical Yearbook, we investigated the spatial and temporal variations of cropland carbon transfer (CCT), an important ecological phenomenon in quantifying the regional carbon budget, in particular, the influencing factors and difference. The results showed that, from 1992 to 2014, the average CCT in Liaoning province was 18.56 TgC yr -1 and decreased from northwest to southeast. CCT spatial variation was primarily affected by the ratio of planting area to regional area (RPR) via its effect on the magnitude of carbon transfer (MCT), which depended mainly on fertilizer usage per area (FUA). From 1992 to 2014, CCT exhibited a significantly increasing trend with a rate of 0.48 TgC yr -1 . The inter-annual variation of CCT was dominated by carbon transfer per planting area (CTP) through its effect on MCT, which significantly correlated with FUA but showed no significant correlation with climatic factors. Therefore, the factors affecting the spatial variation of CCT differed from those that affected its inter-annual variation, indicating that the spatial and temporal variations of ecological phenomena were affected by divergent factors.

Climate and Edaphic Controls on Humid Tropical Forest Tree Height

NASA Astrophysics Data System (ADS)

Yang, Y.; Saatchi, S. S.; Xu, L.

2014-12-01

Uncertainty in the magnitude and spatial variations of forest carbon density in tropical regions is due to under sampling of forest structure from inventory plots and the lack of regional allometry to estimate the carbon density from structure. Here we quantify the variation of tropical forest structure by using more than 2.5 million measurements of canopy height from systematic sampling of Geoscience Laser Altimeter System (GLAS) satellite observations between 2004 to 2008 and examine the climate and edaphic variables influencing the variations. We used top canopy height of GLAS footprints (~ 0.25 ha) to grid the statistical mean and 90 percentile of samples at 0.5 degrees to capture the regional variability of large trees in tropics. GLAS heights were also aggregated based on a stratification of tropical regions using soil, elevation, and forest types. Both approaches provided consistent patterns of statistically dominant large trees and the least heterogeneity, both as strong drivers of distribution of high biomass forests. Statistical models accounting for spatial autocorrelation suggest that climate, soil and spatial features together can explain more than 60% of the variations in observed tree height information, while climate-only variables explains about one third of the first-order changes in tree height. Soil basics, including physical compositions such as clay and sand contents, chemical properties such as PH values and cation-exchange capacity, as well as biological variables such as organic matters, all present independent but statistically significant relationships to tree height variations. The results confirm other landscape and regional studies that soil fertility, geology and climate may jointly control a majority of the regional variations of forest structure in pan-tropics and influencing both biomass stocks and dynamics. Consequently, other factors such as biotic and disturbance regimes, not included in this study, may have less influence on regional variations but strongly mediate landscape and small-scale forest structure and dynamics.

Sex-related shape dimorphism in the human radiocarpal and midcarpal joints.

PubMed

Kivell, Tracy L; Guimont, Isabelle; Wall, Christine E

2013-01-01

Previous research has revealed significant size differences between human male and female carpal bones but it is unknown if there are significant shape differences as well. This study investigated sex-related shape variation and allometric patterns in five carpal bones that make up the radiocarpal and midcarpal joints in modern humans. We found that many aspects of carpal shape (76% of all variables quantified) were similar between males and females, despite variation in size. However, 10 of the shape ratios were significantly different between males and females, with at least one significant shape difference observed in each carpal bone. Within-sex standard major axis regressions (SMA) of the numerator (i.e., the linear variables) on the denominator (i.e., the geometric mean) for each significantly different shape ratio indicated that most linear variables scaled with positive allometry in both males and females, and that for eight of the shape ratios, sex-related shape variation is associated with statistically similar sex-specific scaling relationships. Only the length of the scaphoid body and the height of the lunate triquetrum facet showed a significantly higher SMA slope in females compared with males. These findings indicate that the significant differences in the majority of the shape ratios are a function of subtle (i.e., not statistically significant) scaling differences between males and females. There are a number of potential developmental, functional, and evolutionary factors that may cause sex-related shape differences in the human carpus. The results highlight the potential for subtle differences in scaling to result in functionally significant differences in shape. Copyright © 2012 Wiley Periodicals, Inc.

Multiparametric statistical investigation of seismicity occurred at El Hierro (Canary Islands) from 2011 to 2014

NASA Astrophysics Data System (ADS)

Telesca, Luciano; Lovallo, Michele; Lopez, Carmen; Marti Molist, Joan

2016-03-01

A detailed statistical investigation of the seismicity occurred at El Hierro volcano (Canary Islands) from 2011 to 2014 has been performed by analysing the time variation of four parameters: the Gutenberg-Richter b-value, the local coefficient of variation, the scaling exponent of the magnitude distribution and the main periodicity of the earthquake sequence calculated by using the Schuster's test. These four parameters are good descriptors of the time and magnitude distributions of the seismic sequence, and their variation indicate dynamical changes in the volcanic system. These variations can be attributed to the causes and types of seismicity, thus allowing to distinguish between different host-rock fracturing processes caused by intrusions of magma at different depths and overpressures. The statistical patterns observed among the studied unrest episodes and between them and the eruptive episode of 2011-2012 indicate that the response of the host rock to the deformation imposed by magma intrusion did not differ significantly from one episode to the other, thus suggesting that no significant local stress changes induced by magma intrusion occurred when comparing between all them. Therefore, despite the studied unrest episodes were caused by intrusions of magma at different depths and locations below El Hierro island, the mechanical response of the lithosphere was similar in all cases. This suggests that the reason why the first unrest culminated in an eruption while the other did not, may be related to the role of the regional/local tectonics acting at that moment, rather than to the forceful of magma intrusion.

Structural correlates of Openness and Intellect: Implications for the contribution of personality to creativity.

PubMed

Vartanian, Oshin; Wertz, Christopher J; Flores, Ranee A; Beatty, Erin L; Smith, Ingrid; Blackler, Kristen; Lam, Quan; Jung, Rex E

2018-04-15

Openness/Intellect (i.e., openness to experience) is the Big Five personality factor most consistently associated with individual differences in creativity. Recent psychometric evidence has demonstrated that this factor consists of two distinct aspects-Intellect and Openness. Whereas Intellect reflects perceived intelligence and intellectual engagement, Openness reflects engagement with fantasy, perception, and aesthetics. We investigated the extent to which Openness and Intellect are associated with variations in brain structure as measured by cortical thickness, area, and volume (N = 185). Our results demonstrated that Openness was correlated inversely with cortical thickness and volume in left middle frontal gyrus (BA 6), middle temporal gyrus (MTG, BA 21), and superior temporal gyrus (BA 41), and exclusively with cortical thickness in left inferior parietal lobule (BA 40), right inferior frontal gyrus (IFG, BA 45), and MTG (BA 37). When age and sex were statistically controlled for, the inverse correlations between Openness and cortical thickness remained statistically significant for all regions except left MTG, whereas the correlations involving cortical volume remained statistically significant only for left middle frontal gyrus. There was no statistically significant correlation between Openness and cortical area, and no statistically significant correlation between Intellect and cortical thickness, area, or volume. Our results demonstrate that individual differences in Openness are correlated with variation in brain structure-particularly as indexed by cortical thickness. Given the involvement of the above regions in processes related to memory and cognitive control, we discuss the implications of our findings for the possible contribution of personality to creative cognition. © 2018 Her Majesty the Queen in Right of Canada 2018. Reproduced with permission of the Minister of Health, Canada. Human Brain Mapping.

42 CFR 421.122 - Performance standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... performance, application of acceptable statistical measures of variation to nationwide intermediary experience... or criterion. (b) Factors beyond intermediary's control. To identify measurable factors that significantly affect an intermediary's performance, but that are not within the intermediary's control, CMS will...

Anatomical variations of hepatic arterial system, coeliac trunk and renal arteries: an analysis with multidetector CT angiography.

PubMed

Ugurel, M S; Battal, B; Bozlar, U; Nural, M S; Tasar, M; Ors, F; Saglam, M; Karademir, I

2010-08-01

The purpose of our investigation was to determine the anatomical variations in the coeliac trunk-hepatic arterial system and the renal arteries in patients who underwent multidetector CT (MDCT) angiography of the abdominal aorta for various reasons. A total of 100 patients were analysed retrospectively. The coeliac trunk, hepatic arterial system and renal arteries were analysed individually and anatomical variations were recorded. Statistical analysis of the relationship between hepatocoeliac variations and renal artery variations was performed using a chi(2) test. There was a coeliac trunk trifurcation in 89% and bifurcation in 8% of the cases. Coeliac trunk was absent in 1%, a hepatosplenomesenteric trunk was seen in 1% and a splenomesenteric trunk was present in 1%. Hepatic artery variation was present in 48% of patients. Coeliac trunk and/or hepatic arterial variation was present in 23 (39.7%) of the 58 patients with normal renal arteries, and in 27 (64.3%) of the 42 patients with accessory renal arteries. There was a statistically significant correlation between renal artery variations and coeliac trunk-hepatic arterial system variations (p = 0.015). MDCT angiography permits a correct and detailed evaluation of hepatic and renal vascular anatomy. The prevalence of variations in the coeliac trunk and/or hepatic arteries is increased in people with accessory renal arteries. For that reason, when undertaking angiographic examinations directed towards any single organ, the possibility of variations in the vascular structure of other organs should be kept in mind.

Patterns of shading tolerance determined from experimental ...

EPA Pesticide Factsheets

An extensive review of the experimental literature on seagrass shading evaluated the relationship between experimental light reductions, duration of experiment and seagrass response metrics to determine whether there were consistent statistical patterns. There were highly significant linear relationships of both percent biomass and percent shoot density reduction versus percent light reduction (versus controls), although unexplained variation in the data were high. Duration of exposure affected extent of response for both metrics, but was more clearly a factor in biomass response. Both biomass and shoot density showed linear responses to duration of light reduction for treatments 60%. Unexplained variation was again high, and greater for shoot density than biomass. With few exceptions, regressions of both biomass and shoot density on light reduction for individual species and for genera were statistically significant, but also tended to show high degrees of variability in data. Multivariate regressions that included both percent light reduction and duration of reduction as dependent variables increased the percentage of variation explained in almost every case. Analysis of response data by seagrass life history category (Colonizing, Opportunistic, Persistent) did not yield clearly separate response relationships in most cases. Biomass tended to show somewhat less variation in response to light reduction than shoot density, and of the two, may be the prefe

Inter-annual rainfall variations and suicide in New South Wales, Australia, 1964-2001

NASA Astrophysics Data System (ADS)

Nicholls, Neville; Butler, Colin D.; Hanigan, Ivan

2006-01-01

The suicide rate in New South Wales is shown to be related to annual precipitation, supporting a widespread and long-held assumption that drought in Australia increases the likelihood of suicide. The relationship, although statistically significant, is not especially strong and is confounded by strong, long-term variations in the suicide rate not related to precipitation variations. A decrease in precipitation of about 300 mm would lead to an increase in the suicide rate of approximately 8% of the long-term mean suicide rate.

Functional effects of CCL3L1 copy number

PubMed Central

Carpenter, Danielle; McIntosh, Richard S; Pleass, Richard J; Armour, John AL

2012-01-01

Copy number variation (CNV) is becoming increasingly important as a feature of human variation in disease susceptibility studies. However, the consequences of copy number variation are not so well understood. Here we present data exploring the functional consequences of copy number variation of CCL3L1 in 55 independent UK samples with no known clinical phenotypes. Copy number of CCL3L1 was determined by the paralogue ratio test (PRT), and expression levels of MIP-1α and mRNA from stimulated monocytes were measured and analysed. The data show no statistically significant association of MIP-1α protein levels with copy number. However, there was a significant correlation between copy number and CCL3L1:CCL3 mRNA ratio. The data also provide evidence that expression of CCL3 predominates in both protein and mRNA, and therefore the observed variation of CCL3 is potentially more important biologically than that of copy number variation of CCL3L1. PMID:22476153

The relationship of glutathione-S-transferases copy number variation and indoor air pollution to symptoms and markers of respiratory disease.

PubMed

Hersoug, Lars-Georg; Brasch-Andersen, Charlotte; Husemoen, Lise Lotte Nystrup; Sigsgaard, Torben; Linneberg, Allan

2012-07-01

Exposure to particulate matter (PM) may induce inflammation and oxidative stress in the airways. Carriers of null polymorphisms of glutathione S-transferases (GSTs), which detoxify reactive oxygen species, may be particularly susceptible to the effects of PM. To investigate whether deletions of GSTM1 and GSTT1 modify the potential effects of exposure to indoor sources of PM on symptoms and objective markers of respiratory disease. We conducted a population-based, cross-sectional study of 3471 persons aged 18-69 years. Information about exposure to indoor sources of PM and respiratory symptoms was obtained by a self-administered questionnaire. In addition, measurements of lung function (spirometry) and fractional exhaled nitric oxide were performed. Copy number variation of GSTM1 and GSTT1 was determined by polymerase chain reaction-based assays. We found that none of the symptoms and objective markers of respiratory disease were significantly associated with the GST null polymorphisms. An increasing number of positive alleles of the GSTM1 polymorphism tended to be associated lower prevalence of wheeze, cough, and high forced expiratory volume in 1 s (FEV(1) ), but these trends were not statistically significant. Furthermore, we did not observe any statistically significant interactions between GST copy number variation and exposure to indoor sources of PM in relation to respiratory symptoms and markers. In this adult population, GST copy number variations were not significantly associated with respiratory outcomes and did not modify the effects of self-reported exposure to indoor sources of PM on respiratory outcomes. © 2011 Blackwell Publishing Ltd.

Variations in Vietnamese marriages, births and infant deaths by months of the Julian calendar and years of the Vietnamese and Chinese astrological calendars.

PubMed

Nguyen, M T; Swenson, I

1996-07-01

The timing of births and marriages in Vietnam appears to have some statistically significant relationships with the signs of the Chinese and Vietnamese astrological calendars. Years considered to be good years have significantly more births and marriages than years that are not considered as desirable. Births and marriages also have some significant variations with seasons of the year. Infant deaths do not appear to have any significant relationships with the astrological signs although infant mortality has some significant relationships with seasons of the year. The findings indicate that there is some purposeful planning for marriages and births to coincide with optimal times defined in the astrological calendars.

Impact of seasonal variation, age and smoking status on human semen parameters: The Massachusetts General Hospital experience

PubMed Central

Chen, Zuying; Godfrey-Bailey, Linda; Schiff, Isaac; Hauser, Russ

2004-01-01

Background To investigate the relationship of human semen parameters with season, age and smoking status. Methods The present study used data from subjects recruited into an ongoing cross-sectional study on the relationship between environmental agents and semen characteristics. Our population consisted of 306 patients who presented to the Vincent Memorial Andrology Laboratory of Massachusetts General Hospital for semen evaluation. Sperm concentration and motility were measured with computer aided sperm analysis (CASA). Sperm morphology was scored using Tygerberg Kruger strict criteria. Regression analyses were used to investigate the relationships between semen parameters and season, age and smoking status, adjusting for abstinence interval. Results Sperm concentration in the spring was significantly higher than in winter, fall and summer (p < 0.05). There was suggestive evidence of higher sperm motility and percent of sperm with normal morphology in the spring than in the other seasons. There were no statistically significant relationships between semen parameters and smoking status, though current smokers tended to have lower sperm concentration. We also did not find a statistically significant relationship between age and semen parameters. Conclusions We found seasonal variations in sperm concentration and suggestive evidence of seasonal variation in sperm motility and percent sperm with normal morphology. Although smoking status was not a significant predictor of semen parameters, this may have been due to the small number of current smokers in the study. PMID:15507127

Spatial and temporal snowpack variation in the crown of the continent ecosystem

USGS Publications Warehouse

Selkowitz, D.J.; Fagre, D.B.; Reardon, B.A.

2002-01-01

Snowpack related ecosystem changes such as glacier recession and alpine treeline advance have been documented in the Crown of the Continent Ecosystem (CCE) over the course of the previous 150 years. Using data from the Natural Resource Conservation Service's SNOTEL sites and snow course surveys, we examined the spatial and temporal variation in snowpack in the region. SNOTEL data suggest CCE snowpacks are larger and more persistent than in most regions of the Western U.S., and that water year precipitation, rather than mean temperature, is the primary control on April 1 snow water equivalent (SWE). Snow course data indicate a statistically significant downward trend in mean April 1 SWE for the period 1950-2001 but no statistically significant trend in mean May 1 SWE for the longer period 1922-2001. Further analysis reveals that variations in both April 1 and May 1 mean SWE are closely tied to the Pacific Decadal Oscillation, an ENSO-like interdecadal pattern of Pacific Ocean climate variability. Despite no significant trend in mean May 1 SWE between 1922-2001, glaciers in Glacier National Park receded steadily during this period, implying changing climatic conditions crossed a threshold for glacier mass balance maintenace sometime between the Little Ice Age glacial maxima and 1922.

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students

PubMed Central

Lee, Romeo B.; Baring, Rito V.; Sta. Maria, Madelene A.

2016-01-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students. PMID:27247700

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students.

PubMed

Lee, Romeo B; Baring, Rito V; Sta Maria, Madelene A

2016-02-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students.

Sinonasal anatomical variations: their relationship with chronic rhinosinusitis and effect on the severity of disease-a computerized tomography assisted anatomical and clinical study.

PubMed

Kaygusuz, Ahmet; Haksever, Mehmet; Akduman, Davut; Aslan, Sündüs; Sayar, Zeynep

2014-09-01

The anatomy of the sinonasal area has a very wide rage of anatomical variations. The significance of these anatomical variations in pathogenesis of rhinosinusitis, which is the commonest disease in the region, is still unclear. The aims of the study were to compare the rate of sinonasal anatomical variations with development and severity of chronic rhinosinusitis patients. CT scan of paranasal sinuses images of 99 individuals were retrospectively reviewed. 65 cases of chronic rhinosinusitis (study group) who had undergone endoscopic sinus surgery were compared with 34 cases without chronic rhinosinusitis (control group). Also in study group Lund-Mackay score of the sinus disease were calculated and compared to the rate of related anatomical variations. There were 74 (74.7 %) males and 25 (25.2 %) females with ages ranging from 13 to 70 years (mean 32.2 years). The anatomical variations recorded were: Septal deviation 47 (72.3) in study and 25 (73.5 %) in control group, concha bullosa 27 (41.5 %) in study and 18 (52.9 %) in control group, overpneumatized ethmoid bulla 17 (26.1 %) in study and 14 (41.1 %) in control group, pneumatized uncinate 3 (4.6 %) in study and 3 (8.8 %) in control group, agger nasi 42 (64.6 %) in study and 19 (55.8 %) in control group, paradoxical middle turbinates 9 (13.8 %) in study and 4 (11.7 %) in control group, Onodi cell 6 (9.2 %) in study and 2 (5.8 %) in control group, Haller's cells (infraorbital ethmoid cell) 9 (13.8 %) in study and 7 (20.5 %) in control group. None of these results were statistically significant between study and control group (p > 0.05). Lund-Mackay score (which was assumed to show the severity of the disease) of the maxillary, ethmoid and frontal sinus were calculated and compared to rate of septal deviation, concha bullosa, agger nasi cells. No significant correlation was conducted (p > 0.05). The results of study showed no statistically significant correlation between sinonasal anatomical variations and pathologies of the paranasal sinus. Also these anatomical variations did not increase the severity of pre-existing sinusitis significantly. This is a retrospective cohort study (2b).

A New Performance Improvement Model: Adding Benchmarking to the Analysis of Performance Indicator Data.

PubMed

Al-Kuwaiti, Ahmed; Homa, Karen; Maruthamuthu, Thennarasu

2016-01-01

A performance improvement model was developed that focuses on the analysis and interpretation of performance indicator (PI) data using statistical process control and benchmarking. PIs are suitable for comparison with benchmarks only if the data fall within the statistically accepted limit-that is, show only random variation. Specifically, if there is no significant special-cause variation over a period of time, then the data are ready to be benchmarked. The proposed Define, Measure, Control, Internal Threshold, and Benchmark model is adapted from the Define, Measure, Analyze, Improve, Control (DMAIC) model. The model consists of the following five steps: Step 1. Define the process; Step 2. Monitor and measure the variation over the period of time; Step 3. Check the variation of the process; if stable (no significant variation), go to Step 4; otherwise, control variation with the help of an action plan; Step 4. Develop an internal threshold and compare the process with it; Step 5.1. Compare the process with an internal benchmark; and Step 5.2. Compare the process with an external benchmark. The steps are illustrated through the use of health care-associated infection (HAI) data collected for 2013 and 2014 from the Infection Control Unit, King Fahd Hospital, University of Dammam, Saudi Arabia. Monitoring variation is an important strategy in understanding and learning about a process. In the example, HAI was monitored for variation in 2013, and the need to have a more predictable process prompted the need to control variation by an action plan. The action plan was successful, as noted by the shift in the 2014 data, compared to the historical average, and, in addition, the variation was reduced. The model is subject to limitations: For example, it cannot be used without benchmarks, which need to be calculated the same way with similar patient populations, and it focuses only on the "Analyze" part of the DMAIC model.

Effects of vertebral number variations on carcass traits and genotyping of Vertnin candidate gene in Kazakh sheep.

PubMed

Zhang, Zhifeng; Sun, Yawei; Du, Wei; He, Sangang; Liu, Mingjun; Tian, Changyan

2017-09-01

The vertebral number is associated with body length and carcass traits, which represents an economically important trait in farm animals. The variation of vertebral number has been observed in a few mammalian species. However, the variation of vertebral number and quantitative trait loci in sheep breeds have not been well addressed. In our investigation, the information including gender, age, carcass weight, carcass length and the number of thoracic and lumbar vertebrae from 624 China Kazakh sheep was collected. The effect of vertebral number variation on carcass weight and carcass length was estimated by general linear model. Further, the polymorphic sites of Vertnin ( VRTN ) gene were identified by sequencing, and the association of the genotype and vertebral number variation was analyzed by the one-way analysis of variance model. The variation of thoracolumbar vertebrae number in Kazakh sheep (18 to 20) was smaller than that in Texel sheep (17 to 21). The individuals with 19 thoracolumbar vertebrae (T13L6) were dominant in Kazakh sheep (79.2%). The association study showed that the numbers of thoracolumbar vertebrae were positively correlated with the carcass length and carcass weight, statistically significant with carcass length. To investigate the association of thoracolumbar vertebrae number with VRTN gene, we genotyped the VRTN gene. A total of 9 polymorphic sites were detected and only a single nucleotide polymorphism (SNP) (rs426367238) was suggested to associate with thoracic vertebral number statistically. The variation of thoracolumbar vertebrae number positively associated with the carcass length and carcass weight, especially with the carcass length. VRTN gene polymorphism of the SNP (rs426367238) with significant effect on thoracic vertebral number could be as a candidate marker to further evaluate its role in influence of thoracolumbar vertebral number.

[Hydrologic variability and sensitivity based on Hurst coefficient and Bartels statistic].

PubMed

Lei, Xu; Xie, Ping; Wu, Zi Yi; Sang, Yan Fang; Zhao, Jiang Yan; Li, Bin Bin

2018-04-01

Due to the global climate change and frequent human activities in recent years, the pure stochastic components of hydrological sequence is mixed with one or several of the variation ingredients, including jump, trend, period and dependency. It is urgently needed to clarify which indices should be used to quantify the degree of their variability. In this study, we defined the hydrological variability based on Hurst coefficient and Bartels statistic, and used Monte Carlo statistical tests to test and analyze their sensitivity to different variants. When the hydrological sequence had jump or trend variation, both Hurst coefficient and Bartels statistic could reflect the variation, with the Hurst coefficient being more sensitive to weak jump or trend variation. When the sequence had period, only the Bartels statistic could detect the mutation of the sequence. When the sequence had a dependency, both the Hurst coefficient and the Bartels statistics could reflect the variation, with the latter could detect weaker dependent variations. For the four variations, both the Hurst variability and Bartels variability increased with the increases of variation range. Thus, they could be used to measure the variation intensity of the hydrological sequence. We analyzed the temperature series of different weather stations in the Lancang River basin. Results showed that the temperature of all stations showed the upward trend or jump, indicating that the entire basin had experienced warming in recent years and the temperature variability in the upper and lower reaches was much higher. This case study showed the practicability of the proposed method.

Intercorrelations of Anthropometric Measurements: A Source Book for USA Data

DTIC Science & Technology

1978-05-01

and most important of the statistical measures after the arithmetic mean and standard devi- ation. The coefficient was devised and developed by Francis ... Galton and Karl Pearson in the last decades of the nineteenth century as a measure of the degree of interrelationship or concomitant variation of a...paragraphs--in a wide variety of formulas such as ones for tests of statistical significance and for discriminant functions. Correlation coefficients are

Genetic interactions contribute less than additive effects to quantitative trait variation in yeast

PubMed Central

Bloom, Joshua S.; Kotenko, Iulia; Sadhu, Meru J.; Treusch, Sebastian; Albert, Frank W.; Kruglyak, Leonid

2015-01-01

Genetic mapping studies of quantitative traits typically focus on detecting loci that contribute additively to trait variation. Genetic interactions are often proposed as a contributing factor to trait variation, but the relative contribution of interactions to trait variation is a subject of debate. Here we use a very large cross between two yeast strains to accurately estimate the fraction of phenotypic variance due to pairwise QTL–QTL interactions for 20 quantitative traits. We find that this fraction is 9% on average, substantially less than the contribution of additive QTL (43%). Statistically significant QTL–QTL pairs typically have small individual effect sizes, but collectively explain 40% of the pairwise interaction variance. We show that pairwise interaction variance is largely explained by pairs of loci at least one of which has a significant additive effect. These results refine our understanding of the genetic architecture of quantitative traits and help guide future mapping studies. PMID:26537231

Point and interval estimation of pollinator importance: a study using pollination data of Silene caroliniana.

PubMed

Reynolds, Richard J; Fenster, Charles B

2008-05-01

Pollinator importance, the product of visitation rate and pollinator effectiveness, is a descriptive parameter of the ecology and evolution of plant-pollinator interactions. Naturally, sources of its variation should be investigated, but the SE of pollinator importance has never been properly reported. Here, a Monte Carlo simulation study and a result from mathematical statistics on the variance of the product of two random variables are used to estimate the mean and confidence limits of pollinator importance for three visitor species of the wildflower, Silene caroliniana. Both methods provided similar estimates of mean pollinator importance and its interval if the sample size of the visitation and effectiveness datasets were comparatively large. These approaches allowed us to determine that bumblebee importance was significantly greater than clearwing hawkmoth, which was significantly greater than beefly. The methods could be used to statistically quantify temporal and spatial variation in pollinator importance of particular visitor species. The approaches may be extended for estimating the variance of more than two random variables. However, unless the distribution function of the resulting statistic is known, the simulation approach is preferable for calculating the parameter's confidence limits.

A generalized regression model of arsenic variations in the shallow groundwater of Bangladesh

PubMed Central

Taylor, Richard G.; Chandler, Richard E.

2015-01-01

Abstract Localized studies of arsenic (As) in Bangladesh have reached disparate conclusions regarding the impact of irrigation‐induced recharge on As concentrations in shallow (≤50 m below ground level) groundwater. We construct generalized regression models (GRMs) to describe observed spatial variations in As concentrations in shallow groundwater both (i) nationally, and (ii) regionally within Holocene deposits where As concentrations in groundwater are generally high (>10 μg L−1). At these scales, the GRMs reveal statistically significant inverse associations between observed As concentrations and two covariates: (1) hydraulic conductivity of the shallow aquifer and (2) net increase in mean recharge between predeveloped and developed groundwater‐fed irrigation periods. Further, the GRMs show that the spatial variation of groundwater As concentrations is well explained by not only surface geology but also statistical interactions (i.e., combined effects) between surface geology and mean groundwater recharge, thickness of surficial silt and clay, and well depth. Net increases in recharge result from intensive groundwater abstraction for irrigation, which induces additional recharge where it is enabled by a permeable surface geology. Collectively, these statistical associations indicate that irrigation‐induced recharge serves to flush mobile As from shallow groundwater. PMID:27524841

Spatial scan statistics for detection of multiple clusters with arbitrary shapes.

PubMed

Lin, Pei-Sheng; Kung, Yi-Hung; Clayton, Murray

2016-12-01

In applying scan statistics for public health research, it would be valuable to develop a detection method for multiple clusters that accommodates spatial correlation and covariate effects in an integrated model. In this article, we connect the concepts of the likelihood ratio (LR) scan statistic and the quasi-likelihood (QL) scan statistic to provide a series of detection procedures sufficiently flexible to apply to clusters of arbitrary shape. First, we use an independent scan model for detection of clusters and then a variogram tool to examine the existence of spatial correlation and regional variation based on residuals of the independent scan model. When the estimate of regional variation is significantly different from zero, a mixed QL estimating equation is developed to estimate coefficients of geographic clusters and covariates. We use the Benjamini-Hochberg procedure (1995) to find a threshold for p-values to address the multiple testing problem. A quasi-deviance criterion is used to regroup the estimated clusters to find geographic clusters with arbitrary shapes. We conduct simulations to compare the performance of the proposed method with other scan statistics. For illustration, the method is applied to enterovirus data from Taiwan. © 2016, The International Biometric Society.

The Timing of First Marriage: Are There Religious Variations?

ERIC Educational Resources Information Center

Xu, Xiaohe; Hudspeth, Clark D.; Bartkowski, John P.

2005-01-01

Using survey data from a nationally representative sample, this article explores how marriage timing varies across major religious denominations. Survival analysis indicates that net of statistical controls, Catholics, moderate Protestants, conservative Protestants, and Mormons marry significantly earlier than their unaffiliated counterparts. This…

Associations between the social organization of communities and psychiatric disorders in rural Asia.

PubMed

Axinn, William G; Ghimire, Dirgha J; Williams, Nathalie E; Scott, Kate M

2015-10-01

We provide rare evidence of factors producing psychiatric variation in a general population sample from rural South Asia. The setting is particularly useful for demonstrating that variations in the social organization of communities, often difficult to observe in rich countries, are associated with important variations in mental health. Clinically validated survey measures are used to document variation in psychiatric disorders among 401 adults. This sample is chosen from a systematic sample of the general population of rural Nepal, in a community-level-controlled comparison design. Multilevel logistic regression is used to estimate multivariate models of the association between community-level nonfamily social organization and individual-level psychiatric disorders. Schools, markets, health services and social support groups each substantially reduce the odds of depression, post-traumatic stress disorder (PTSD), intermittent explosive disorder and anxiety disorders. Associations between schools, health services and social support groups and depression are statistically significant and independent of each other. The association between access to markets and PTSD is statistically significant and independent of other social organization and support groups. Community integration of some nonfamily social organizations promotes mental health in ways that may go unobserved in settings with many such organizations. More research on the mechanisms producing these associations is likely to reveal potential avenues for public policy and programs to improve mental health in the general population.

The effect of the presence of the accessory maxillary ostium on the maxillary sinus.

PubMed

Yenigun, Alper; Fazliogullari, Zeliha; Gun, Cihat; Uysal, Ismihan Ilknur; Nayman, Alaaddin; Karabulut, Ahmet Kagan

2016-12-01

This study was conducted to investigate the presence of the accessory maxillary ostium and its effects on the maxillary sinus, and the concurrent occurrence of morphological variations of neighboring anatomical structures. This study was performed in a tertiary referral center. This is a cross-sectional retrospective study that evaluated coronal CTs of patients to determine the frequency of the accessory maxillary ostium and investigated any simultaneous morphological variations in neighboring anatomical structures. The presence of the accessory maxillary ostium (AMO) plus any concurrent morphological variations of neighboring structures were investigated in 377 patients, with 754 sides. AMO was found to be present in 19.1 % (72/377) of the patients. A concurrent mucus retention cyst was found to be statistically significant on both sides (right side: p = 0.00, left side: p = 0.00), as well as mucosal thickening (right side: p = 0.00, left side: p = 0.00), and maxillary sinusitis (right side: p = 0.04, left side: p = 0.03). No other concurrent variations of statistical significance were detected in the neighboring structures. Our study demonstrated that with the presence of AMO, the likelihood of encountering a mucus retention cyst (48.6 %) had an approximately threefold increase, and that of encountering mucosal thickening (43.0 %) and maxillary sinusitis (29.1 %) had a twofold increase.

Associations between the Social Organization of Communities and Psychiatric Disorders in Rural Asia

PubMed Central

Axinn, William G.; Ghimire, Dirgha J.; Williams, Nathalie E.; Scott, Kate M.

2015-01-01

Purpose We provide rare evidence of factors producing psychiatric variation in a general population sample from rural South Asia. The setting is particularly useful for demonstrating that variations in the social organization of communities, often difficult to observe in rich countries, are associated with important variations in mental health. Methods Clinically validated survey measures are used to document variation in psychiatric disorders among 401 adults. This sample is chosen from a systematic sample of the general population of rural Nepal, in a community-level controlled comparison design. Multilevel logistic regression is used to estimate multivariate models of the association between community-level nonfamily social organization and individual-level psychiatric disorders. Results Schools, markets, health services and social support groups each substantially reduce the odds of depression, post-traumatic stress disorder (PTSD), intermittent explosive disorder (IED) and anxiety disorders. Associations between schools, health services and social support groups and depression are statistically significant and independent of each other. The association between access to markets and PTSD is statistically significant and independent of other social organization and support groups. Conclusions Community integration of some nonfamily social organizations promotes mental health in ways that may go unobserved in settings with many such organizations. More research on the mechanisms producing these associations is likely to reveal potential avenues for public policy and programs to improve mental health in the general population. PMID:25796491

Evidence of a genetic link between endometriosis and ovarian cancer.

PubMed

Lee, Alice W; Templeman, Claire; Stram, Douglas A; Beesley, Jonathan; Tyrer, Jonathan; Berchuck, Andrew; Pharoah, Paul P; Chenevix-Trench, Georgia; Pearce, Celeste Leigh

2016-01-01

To evaluate whether endometriosis-associated genetic variation affects risk of ovarian cancer. Pooled genetic analysis. University hospital. Genetic data from 46,176 participants (15,361 ovarian cancer cases and 30,815 controls) from 41 ovarian cancer studies. None. Endometriosis-associated genetic variation and ovarian cancer. There was significant evidence of an association between endometriosis-related genetic variation and ovarian cancer risk, especially for the high-grade serous and clear cell histotypes. Overall we observed 15 significant burden statistics, which was three times more than expected. By focusing on candidate regions from a phenotype associated with ovarian cancer, we have shown a clear genetic link between endometriosis and ovarian cancer that warrants further follow-up. The functional significance of the identified regions and SNPs is presently uncertain, though future fine mapping and histotype-specific functional analyses may shed light on the etiologies of both gynecologic conditions. Copyright © 2016. Published by Elsevier Inc.

Turbomachine Sealing and Secondary Flows - Part 3. Part 3; Review of Power-Stream Support, Unsteady Flow Systems, Seal and Disk Cavity Flows, Engine Externals, and Life and Reliability Issues

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Steinetz, B. M.; Zaretsky, E. V.; Athavale, M. M.; Przekwas, A. J.

2004-01-01

The issues and components supporting the engine power stream are reviewed. It is essential that companies pay close attention to engine sealing issues, particularly on the high-pressure spool or high-pressure pumps. Small changes in these systems are reflected throughout the entire engine. Although cavity, platform, and tip sealing are complex and have a significant effect on component and engine performance, computational tools (e.g., NASA-developed INDSEAL, SCISEAL, and ADPAC) are available to help guide the designer and the experimenter. Gas turbine engine and rocket engine externals must all function efficiently with a high degree of reliability in order for the engine to run but often receive little attention until they malfunction. Within the open literature statistically significant data for critical engine components are virtually nonexistent; the classic approach is deterministic. Studies show that variations with loading can have a significant effect on component performance and life. Without validation data they are just studies. These variations and deficits in statistical databases require immediate attention.

Within-individual variation in bullfrog vocalizations: implications for a vocally mediated social recognition system.

PubMed

Bee, Mark A

2004-12-01

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.

Completion of the Circle of Willis Varies by Gender, Age, and Indication for Computed Tomography Angiography.

PubMed

Zaninovich, Orel A; Ramey, Wyatt L; Walter, Christina M; Dumont, Travis M

2017-10-01

The circle of Willis (CoW) is the foremost anastomosis and blood distribution center of the brain. Its effectiveness depends on its completion and the size and patency of its vessels. Gender-related and age-related anatomic variations in the CoW may play an important role in the pathogenesis of cerebrovascular diseases. In this study, we analyzed computed tomography angiograms (CTAs) to assess for differences in CoW completion related to gender, age, and indication for CTA. A total of 834 CTAs were retrospectively analyzed for all CoW vessels to compare the incidence of complete CoW and variation frequency based on gender, age, and indication. The incidence of complete CoW was 37.1% overall. CoW completion showed a statistically significant decrease with increasing age for all age groups in both men (47.0%, 29.4%, 18.8%) and women (59.1%, 44.2%, 30.9%). Completion was greater in women (43.8%) than in men (31.2%) overall and for all age groups. These gender differences were all statistically significant except for the 18-39 years age group. The most frequent of the 28 CoW variations were absent posterior communicating artery (PCOM) bilaterally (17.1%), right PCOM (15.3%), and left PCOM (10.9%). Ischemic stroke and the 18-39 years age group of hemorrhagic stroke showed a statistically significant reduction in completion relative to trauma. The incidence of complete CoW is likely greater in women for all age groups and likely decreases with age in both genders. The most frequently absent vessel is likely the PCOM, either unilaterally or bilaterally. Completion may play a role in ischemic stroke and a subset of patients with hemorrhagic stroke. Copyright © 2017 Elsevier Inc. All rights reserved.

Genetic variation in chinook, Oncorhynchus tshawytscha, and coho, O. Kisutch

USGS Publications Warehouse

Reisenbichler, R.R.; Phelps, S.R.

1987-01-01

We used starch-gel electrophoresis to genetically characterize the populations of chinook salmon, Oncorhynchus tshawytscha, and coho salmon, O. kisutch, in the major drainages of the north coast of Washington (the Quillayute, Uoh, Queets, and Quinault Rivers). Of 55 loci examined for electrophoretically detectable variation. 6 were polymorphic (frequency of the common allele was less than 0.95) in chinook salmon and 3 in coho salmon. Statistical tests of interdrainage and intradrainage variation for coho salmon were tenuous because most of the fish examined were from a single year class so that we could not account for variation among year classes. Nevertheless, these tests suggested that distinct stocks ofcoho salmon exist within drainages. and that variation was not significantly greater among drainages than within drainages. Interdrainage variation for wild chinook salmon was not significant. The data suggested that summer chinook salmon were electrophoretically different from fall chinook salmon, and the hatchery populations of chinook salmon were distinct from wild fish. A hatchery population developed primarily from north coast fish was electrophoretically more similar to wild chinook salmon than were the others.

Institute for Brain and Neural Systems

DTIC Science & Technology

2009-10-06

to deal with computational complexity when analyzing large amounts of information in visual scenes. It seems natural that in addition to exploring...algorithms using methods from statistical pattern recognition and machine learning. Over the last fifteen years, significant advances had been made in...recognition, robustness to noise and ability to cope with significant variations in lighting conditions. Identifying an occluded target adds another layer of

Variability and similarities in the structural properties of two related Laminaria kelp species

NASA Astrophysics Data System (ADS)

Henry, Pierre-Yves

2018-01-01

Kelps of the genus Laminaria have long been studied and shown to exhibit a seasonal shift in growth and morphology, as nutrients and light levels change during the year. However, the variation of kelp biomechanical properties has been little explored despite the importance of these properties for the interaction of kelp with the flow. Previous research showed that aging does influence the algae biomechanical properties, so this study further investigates the variability of kelp biomechanical properties and morphological characteristics at a given site as a function of the season (growth phase), species, and different kelp parts. Mechanical parameters and morphological characteristics were measured on kelps sampled in winter and summer, and DNA sequencing was used to identify the two related species, L. digitata and L. hyperborea. Descriptive statistics and statistical analysis were used to detect trends in the modulation of kelp mechanical design. Although two distinct species were identified, only minor structural differences were observed between them. The biomechanical properties varied significantly along the kelp, and significant seasonal shifts occurred at the blade level, in relation to the different morphological changes during blade renewal. In general, the variations of the structural properties were mostly linked to the blade growth activity. The absence of significant variation in the mechanical design of the two species highlights the significance of the adaptation to the same local environmental conditions, this adaptation being a key process in vegetation-flow interactions and having implications on the interaction between kelp and hydrodynamics.

On Teaching about the Coefficient of Variation in Introductory Statistics Courses

ERIC Educational Resources Information Center

Trafimow, David

2014-01-01

The standard deviation is related to the mean by virtue of the coefficient of variation. Teachers of statistics courses can make use of that fact to make the standard deviation more comprehensible for statistics students.

Variation in the CYP19A1 gene and risk of colon and rectal cancer

PubMed Central

Slattery, Martha L.; Lundgreen, Abbie; Herrick, Jennifer S.; Kadlubar, Susan; Caan, Bette J.; Potter, John D.; Wolff, Roger K.

2011-01-01

CYP19A1, or aromatase, influences estrogen-metabolizing enzymes and may influence cancer risk. We examine variation in the CYP19A1 gene and risk of colorectal cancer using data from population-based case–control studies (colon n = 1,574 cases, 1,970 controls; rectal n = 791 cases, 999 controls). Four SNPs were statistically significantly associated with colon cancer and four were associated with rectal cancer. After adjustment for multiple comparisons, the AA genotype of rs12591359 was associated with an increased risk of colon cancer (OR 1.44 95% CI 1.16–1.80) and the AA genotype of rs2470144 was associated with a reduced risk of rectal cancer (OR 0.65 95% CI 0.50–0.84). Variants of CYP19A1 were associated with CIMP+ and CIMP+/KRAS2-mutated tumors. CT/TT genotypes of rs1961177 were significantly associated with an increased likelihood of a MSI+ colon tumor (OR 1.77 95% CI 1.26–2.37). We observed statistically significant interactions between genetic variation in NFκB1 and CYP19A1 for both colon and rectal cancer. Our data suggest the importance of CYP19A1 in the development of colon and rectal cancer and that estrogen may influence risk through an inflammation-related mechanism. PMID:21479914

Geographic Variation of Amyotrophic Lateral Sclerosis Incidence in New Jersey, 2009–2011

PubMed Central

Henry, Kevin A.; Fagliano, Jerald; Jordan, Heather M.; Rechtman, Lindsay; Kaye, Wendy E.

2015-01-01

Few analyses in the United States have examined geographic variation and socioeconomic disparities in amyotrophic lateral sclerosis (ALS) incidence, because of lack of population-based incidence data. In this analysis, we used population-based ALS data to identify whether ALS incidence clusters geographically and to determine whether ALS risk varies by area-based socioeconomic status (SES). This study included 493 incident ALS cases diagnosed (via El Escorial criteria) in New Jersey between 2009 and 2011. Geographic variation and clustering of ALS incidence was assessed using a spatial scan statistic and Bayesian geoadditive models. Poisson regression was used to estimate the associations between ALS risk and SES based on census-tract median income while controlling for age, sex, and race. ALS incidence varied across and within counties, but there were no statistically significant geographic clusters. SES was associated with ALS incidence. After adjustment for age, sex, and race, the relative risk of ALS was significantly higher (relative risk (RR) = 1.37, 95% confidence interval (CI): 1.02, 1.82) in the highest income quartile than in the lowest. The relative risk of ALS was significantly lower among blacks (RR = 0.57, 95% CI: 0.39, 0.83) and Asians (RR = 0.63, 95% CI: 0.41, 0.97) than among whites. Our findings suggest that ALS incidence in New Jersey appears to be associated with SES and race. PMID:26041711

Study of the relationship between solar activity and terrestrial weather

NASA Technical Reports Server (NTRS)

Sturrock, P. A.; Brueckner, G. E.; Dickinson, R. E.; Fukuta, N.; Lanzerotti, L. J.; Lindzen, R. S.; Park, C. G.; Wilcox, J. M.

1976-01-01

Evidence for some connection between weather and solar related phenomena is presented. Historical data of world wide temperature variations with relationship to change in solar luminosity are examined. Several test methods for estimating the statistical significance of such phenomena are discussed in detail.

Human genetic variation and yellow fever mortality during 19th century U.S. epidemics.

PubMed

Blake, Lauren E; Garcia-Blanco, Mariano A

2014-06-03

We calculated the incidence, mortality, and case fatality rates for Caucasians and non-Caucasians during 19th century yellow fever (YF) epidemics in the United States and determined statistical significance for differences in the rates in different populations. We evaluated nongenetic host factors, including socioeconomic, environmental, cultural, demographic, and acquired immunity status that could have influenced these differences. While differences in incidence rates were not significant between Caucasians and non-Caucasians, differences in mortality and case fatality rates were statistically significant for all epidemics tested (P < 0.01). Caucasians diagnosed with YF were 6.8 times more likely to succumb than non-Caucasians with the disease. No other major causes of death during the 19th century demonstrated a similar mortality skew toward Caucasians. Nongenetic host factors were examined and could not explain these large differences. We propose that the remarkably lower case mortality rates for individuals of non-Caucasian ancestry is the result of human genetic variation in loci encoding innate immune mediators. Different degrees of severity of yellow fever have been observed across diverse populations, but this study is the first to demonstrate a statistically significant association between ancestry and the outcome of yellow fever (YF). With the global burden of mosquito-borne flaviviral infections, such as YF and dengue, on the rise, identifying and characterizing host factors could prove pivotal in the prevention of epidemics and the development of effective treatments. Copyright © 2014 Blake and Garcia-Blanco.

Regional variations in the management of testicular or ovotesticular disorders of sex development.

PubMed

Josso, N; Audi, L; Shaw, G

2011-01-01

Disorders of sex development arise in parts of the world with different socio-economic and cultural characteristics. We wished to determine the regional variations in the management of these conditions. A questionnaire was e-mailed to the 650 members of the European Society for Paediatric Endocrinology (ESPE), an international society with a mainly European membership but which also includes professionals from other continents. Results were subjected to statistical analysis. A total of 62 answers were received, a satisfactory rate given that not all members are involved in this issue. Results show statistically significant regional differences for available diagnostic resources, age of the patient at gender assignment, parameters considered important for gender assignment, and timing of discussion of various issues with parents and patient. The regional variations exist not only between different continents, as already demonstrated by others, but also between Northern, Latin and Eastern European countries. This suggests that 'one-fits-all' guidelines for management are not appropriate. Copyright © 2011 S. Karger AG, Basel.

A new statistic for identifying batch effects in high-throughput genomic data that uses guided principal component analysis.

PubMed

Reese, Sarah E; Archer, Kellie J; Therneau, Terry M; Atkinson, Elizabeth J; Vachon, Celine M; de Andrade, Mariza; Kocher, Jean-Pierre A; Eckel-Passow, Jeanette E

2013-11-15

Batch effects are due to probe-specific systematic variation between groups of samples (batches) resulting from experimental features that are not of biological interest. Principal component analysis (PCA) is commonly used as a visual tool to determine whether batch effects exist after applying a global normalization method. However, PCA yields linear combinations of the variables that contribute maximum variance and thus will not necessarily detect batch effects if they are not the largest source of variability in the data. We present an extension of PCA to quantify the existence of batch effects, called guided PCA (gPCA). We describe a test statistic that uses gPCA to test whether a batch effect exists. We apply our proposed test statistic derived using gPCA to simulated data and to two copy number variation case studies: the first study consisted of 614 samples from a breast cancer family study using Illumina Human 660 bead-chip arrays, whereas the second case study consisted of 703 samples from a family blood pressure study that used Affymetrix SNP Array 6.0. We demonstrate that our statistic has good statistical properties and is able to identify significant batch effects in two copy number variation case studies. We developed a new statistic that uses gPCA to identify whether batch effects exist in high-throughput genomic data. Although our examples pertain to copy number data, gPCA is general and can be used on other data types as well. The gPCA R package (Available via CRAN) provides functionality and data to perform the methods in this article. reesese@vcu.edu

Variation trend of snowfall in the Kamikochi region of the Japanese Alps

NASA Astrophysics Data System (ADS)

Suzuki, K.

2017-12-01

The Japanese Alps experience exceptionally heavy snowfall, extreme even by global standards, and in spring and summer the melting snow becomes a valuable water resource. The snow effectively acts as a natural dam when it accumulates in watersheds during winter. However, there have been no observations of the amount of snow in high-altitude regions of Japan. Therefore, we cannot discuss the effect of global warming on the change in the amount of snow in these regions based on direct observation data. We were, however, able to obtain climatic and hydrologic data for high-altitude sites in the Japanese Alps, and discuss the variations in these conditions in the Kamikochi region (altitude 1490 m-3190 m) of the Japanese Alps over a 68-year period using these observed data. No long-term trends are observed in the annual mean, maximum, or minimum temperatures at Taisho-ike from 1945 to 2012; the total annual precipitation shows a statistically significant decreasing trend. The annual total snowfall at Taisho-ike from 1969 to 2012 shows a statistically significant increasing trend. The annual total runoff of the Azusa River from 1945 to 2012 shows a statistically significant increasing trend, as does the snowmelt runoff to the river (which occurs from May to July). We can thus conclude that the annual snowfall in the Azusa River catchment has increased in recent years.

Fluency variation in adolescents.

PubMed

Furquim de Andrade, Claudia Regina; de Oliveira Martins, Vanessa

2007-10-01

The Speech Fluency Profile of fluent adolescent speakers of Brazilian Portuguese, were examined with respect to gender and neurolinguistic variations. Speech samples of 130 male and female adolescents, aged between 12;0 and 17;11 years were gathered. They were analysed according to type of speech disruption; speech rate; and frequency of speech disruptions. Statistical analysis did not find significant differences between genders for the variables studied. However, regarding the phases of adolescence (early: 12;0-14;11 years; late: 15;0-17;11 years), statistical differences were observed for all of the variables. As for neurolinguistic maturation, a decrease in the number of speech disruptions and an increase in speech rate occurred during the final phase of adolescence, indicating that the maturation of the motor and linguistic processes exerted an influence over the fluency profile of speech.

Genetic Variation in the Raptor Gene Is Associated With Overweight But Not Hypertension in American Men of Japanese Ancestry

PubMed Central

Carnes, Bruce A.; Chen, Randi; Donlon, Timothy A.; He, Qimei; Grove, John S.; Masaki, Kamal H.; Elliott, Ayako; Willcox, Donald C.; Allsopp, Richard; Willcox, Bradley J.

2015-01-01

BACKGROUND The mechanistic target of rapamycin (mTOR) pathway is pivotal for cell growth. Regulatory associated protein of mTOR complex I (Raptor) is a unique component of this pro-growth complex. The present study tested whether variation across the raptor gene (RPTOR) is associated with overweight and hypertension. METHODS We tested 61 common (allele frequency ≥ 0.1) tagging single nucleotide polymorphisms (SNPs) that captured most of the genetic variation across RPTOR in 374 subjects of normal lifespan and 439 subjects with a lifespan exceeding 95 years for association with overweight/obesity, essential hypertension, and isolated systolic hypertension. Subjects were drawn from the Honolulu Heart Program, a homogeneous population of American men of Japanese ancestry, well characterized for phenotypes relevant to conditions of aging. Hypertension status was ascertained when subjects were 45–68 years old. Statistical evaluation involved contingency table analysis, logistic regression, and the powerful method of recursive partitioning. RESULTS After analysis of RPTOR genotypes by each statistical approach, we found no significant association between genetic variation in RPTOR and either essential hypertension or isolated systolic hypertension. Models generated by recursive partitioning analysis showed that RPTOR SNPs significantly enhanced the ability of the model to accurately assign individuals to either the overweight/obese or the non-overweight/obese groups (P = 0.008 by 1-tailed Z test). CONCLUSION Common genetic variation in RPTOR is associated with overweight/obesity but does not discernibly contribute to either essential hypertension or isolated systolic hypertension in the population studied. PMID:25249372

Towards Structural Analysis of Audio Recordings in the Presence of Musical Variations

NASA Astrophysics Data System (ADS)

Müller, Meinard; Kurth, Frank

2006-12-01

One major goal of structural analysis of an audio recording is to automatically extract the repetitive structure or, more generally, the musical form of the underlying piece of music. Recent approaches to this problem work well for music, where the repetitions largely agree with respect to instrumentation and tempo, as is typically the case for popular music. For other classes of music such as Western classical music, however, musically similar audio segments may exhibit significant variations in parameters such as dynamics, timbre, execution of note groups, modulation, articulation, and tempo progression. In this paper, we propose a robust and efficient algorithm for audio structure analysis, which allows to identify musically similar segments even in the presence of large variations in these parameters. To account for such variations, our main idea is to incorporate invariance at various levels simultaneously: we design a new type of statistical features to absorb microvariations, introduce an enhanced local distance measure to account for local variations, and describe a new strategy for structure extraction that can cope with the global variations. Our experimental results with classical and popular music show that our algorithm performs successfully even in the presence of significant musical variations.

Statistical metrology—measurement and modeling of variation for advanced process development and design rule generation

NASA Astrophysics Data System (ADS)

Boning, Duane S.; Chung, James E.

1998-11-01

Advanced process technology will require more detailed understanding and tighter control of variation in devices and interconnects. The purpose of statistical metrology is to provide methods to measure and characterize variation, to model systematic and random components of that variation, and to understand the impact of variation on both yield and performance of advanced circuits. Of particular concern are spatial or pattern-dependencies within individual chips; such systematic variation within the chip can have a much larger impact on performance than wafer-level random variation. Statistical metrology methods will play an important role in the creation of design rules for advanced technologies. For example, a key issue in multilayer interconnect is the uniformity of interlevel dielectric (ILD) thickness within the chip. For the case of ILD thickness, we describe phases of statistical metrology development and application to understanding and modeling thickness variation arising from chemical-mechanical polishing (CMP). These phases include screening experiments including design of test structures and test masks to gather electrical or optical data, techniques for statistical decomposition and analysis of the data, and approaches to calibrating empirical and physical variation models. These models can be integrated with circuit CAD tools to evaluate different process integration or design rule strategies. One focus for the generation of interconnect design rules are guidelines for the use of "dummy fill" or "metal fill" to improve the uniformity of underlying metal density and thus improve the uniformity of oxide thickness within the die. Trade-offs that can be evaluated via statistical metrology include the improvements to uniformity possible versus the effect of increased capacitance due to additional metal.

What is too much variation? The null hypothesis in small-area analysis.

PubMed Central

Diehr, P; Cain, K; Connell, F; Volinn, E

1990-01-01

A small-area analysis (SAA) in health services research often calculates surgery rates for several small areas, compares the largest rate to the smallest, notes that the difference is large, and attempts to explain this discrepancy as a function of service availability, physician practice styles, or other factors. SAAs are often difficult to interpret because there is little theoretical basis for determining how much variation would be expected under the null hypothesis that all of the small areas have similar underlying surgery rates and that the observed variation is due to chance. We developed a computer program to simulate the distribution of several commonly used descriptive statistics under the null hypothesis, and used it to examine the variability in rates among the counties of the state of Washington. The expected variability when the null hypothesis is true is surprisingly large, and becomes worse for procedures with low incidence, for smaller populations, when there is variability among the populations of the counties, and when readmissions are possible. The characteristics of four descriptive statistics were studied and compared. None was uniformly good, but the chi-square statistic had better performance than the others. When we reanalyzed five journal articles that presented sufficient data, the results were usually statistically significant. Since SAA research today is tending to deal with low-incidence events, smaller populations, and measures where readmissions are possible, more research is needed on the distribution of small-area statistics under the null hypothesis. New standards are proposed for the presentation of SAA results. PMID:2312306

What is too much variation? The null hypothesis in small-area analysis.

PubMed

Diehr, P; Cain, K; Connell, F; Volinn, E

1990-02-01

A small-area analysis (SAA) in health services research often calculates surgery rates for several small areas, compares the largest rate to the smallest, notes that the difference is large, and attempts to explain this discrepancy as a function of service availability, physician practice styles, or other factors. SAAs are often difficult to interpret because there is little theoretical basis for determining how much variation would be expected under the null hypothesis that all of the small areas have similar underlying surgery rates and that the observed variation is due to chance. We developed a computer program to simulate the distribution of several commonly used descriptive statistics under the null hypothesis, and used it to examine the variability in rates among the counties of the state of Washington. The expected variability when the null hypothesis is true is surprisingly large, and becomes worse for procedures with low incidence, for smaller populations, when there is variability among the populations of the counties, and when readmissions are possible. The characteristics of four descriptive statistics were studied and compared. None was uniformly good, but the chi-square statistic had better performance than the others. When we reanalyzed five journal articles that presented sufficient data, the results were usually statistically significant. Since SAA research today is tending to deal with low-incidence events, smaller populations, and measures where readmissions are possible, more research is needed on the distribution of small-area statistics under the null hypothesis. New standards are proposed for the presentation of SAA results.

On the Complexity of Race

ERIC Educational Resources Information Center

Zyphur, Michael J.

2006-01-01

Although a variety of studies have indicated that using statistical clustering techniques to examine genetic information may allow for geographically based groupings of individuals that tenuously map onto some conceptions of race, these studies have also indicated that the amount of genetic variation within these groupings is significantly larger…

Student Effort, Consistency, and Online Performance

ERIC Educational Resources Information Center

Patron, Hilde; Lopez, Salvador

2011-01-01

This paper examines how student effort, consistency, motivation, and marginal learning, influence student grades in an online course. We use data from eleven Microeconomics courses taught online for a total of 212 students. Our findings show that consistency, or less time variation, is a statistically significant explanatory variable, whereas…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, Michael D.; Dater, Manasi; Whitaker, Ross

In this study, statistical shape modeling (SSM) was used to quantify three-dimensional (3D) variation and morphologic differences between femurs with and without cam femoroacetabular impingement (FAI). 3D surfaces were generated from CT scans of femurs from 41 controls and 30 cam FAI patients. SSM correspondence particles were optimally positioned on each surface using a gradient descent energy function. Mean shapes for control and patient groups were defined from the resulting particle configurations. Morphological differences between group mean shapes and between the control mean and individual patients were calculated. Principal component analysis was used to describe anatomical variation present in bothmore » groups. The first 6 modes (or principal components) captured statistically significant shape variations, which comprised 84% of cumulative variation among the femurs. Shape variation was greatest in femoral offset, greater trochanter height, and the head-neck junction. The mean cam femur shape protruded above the control mean by a maximum of 3.3 mm with sustained protrusions of 2.5-3.0 mm along the anterolateral head-neck junction and distally along the anterior neck, corresponding well with reported cam lesion locations and soft-tissue damage. This study provides initial evidence that SSM can describe variations in femoral morphology in both controls and cam FAI patients and may be useful for developing new measurements of pathological anatomy. SSM may also be applied to characterize cam FAI severity and provide templates to guide patient-specific surgical resection of bone.« less

Estimation of trends

NASA Technical Reports Server (NTRS)

1981-01-01

The application of statistical methods to recorded ozone measurements. The effects of a long term depletion of ozone at magnitudes predicted by the NAS is harmful to most forms of life. Empirical prewhitening filters the derivation of which is independent of the underlying physical mechanisms were analyzed. Statistical analysis performs a checks and balances effort. Time series filters variations into systematic and random parts, errors are uncorrelated, and significant phase lag dependencies are identified. The use of time series modeling to enhance the capability of detecting trends is discussed.

An X-ray method for detecting substructure in galaxy clusters - Application to Perseus, A2256, Centaurus, Coma, and Sersic 40/6

NASA Technical Reports Server (NTRS)

Mohr, Joseph J.; Fabricant, Daniel G.; Geller, Margaret J.

1993-01-01

We use the moments of the X-ray surface brightness distribution to constrain the dynamical state of a galaxy cluster. Using X-ray observations from the Einstein Observatory IPC, we measure the first moment FM, the ellipsoidal orientation angle, and the axial ratio at a sequence of radii in the cluster. We argue that a significant variation in the image centroid FM as a function of radius is evidence for a nonequilibrium feature in the intracluster medium (ICM) density distribution. In simple terms, centroid shifts indicate that the center of mass of the ICM varies with radius. This variation is a tracer of continuing dynamical evolution. For each cluster, we evaluate the significance of variations in the centroid of the IPC image by computing the same statistics on an ensemble of simulated cluster images. In producing these simulated images we include X-ray point source emission, telescope vignetting, Poisson noise, and characteristics of the IPC. Application of this new method to five Abell clusters reveals that the core of each one has significant substructure. In addition, we find significant variations in the orientation angle and the axial ratio for several of the clusters.

Time-course variation of statistics embedded in music: Corpus study on implicit learning and knowledge.

PubMed

Daikoku, Tatsuya

2018-01-01

Learning and knowledge of transitional probability in sequences like music, called statistical learning and knowledge, are considered implicit processes that occur without intention to learn and awareness of what one knows. This implicit statistical knowledge can be alternatively expressed via abstract medium such as musical melody, which suggests this knowledge is reflected in melodies written by a composer. This study investigates how statistics in music vary over a composer's lifetime. Transitional probabilities of highest-pitch sequences in Ludwig van Beethoven's Piano Sonata were calculated based on different hierarchical Markov models. Each interval pattern was ordered based on the sonata opus number. The transitional probabilities of sequential patterns that are musical universal in music gradually decreased, suggesting that time-course variations of statistics in music reflect time-course variations of a composer's statistical knowledge. This study sheds new light on novel methodologies that may be able to evaluate the time-course variation of composer's implicit knowledge using musical scores.

Space weather influence on the agriculture technology and wheat prices in the medieval England (1259-1703) through cosmic ray/solar activity cycle variations

NASA Astrophysics Data System (ADS)

Dorman, L. I.; Pustil'Nik, L. A.; Yom Din, G.

2003-04-01

The database of Professor Rogers (1887), which includes wheat prices in England in the Middle Ages (1249-1703) was used to search for possible manifestations of solar activity and cosmic ray intensity variations. The main object of our statistical analysis is investigation of bursts of prices. Our study shows that bursts and troughs of wheat prices take place at extreme states (maximums or minimums) of solar activity cycles. We present a conceptual model of possible modes for sensitivity of wheat prices to weather conditions, caused by cosmic ray intensity solar cycle variations, and compare the expected price fluctuations with wheat price variations recorded in the Medieval England. We compared statistical properties of the intervals between price bursts with statistical properties of the intervals between extremes (minimums) of solar cycles during the years 1700-2000. The medians of both samples have the values of 11.00 and 10.7 years; standard deviations are 1.44 and 1.53 years for prices and for solar activity, respectively. The hypothesis that the frequency distributions are the same for both of the samples have significance level >95%. In the next step we analyzed direct links between wheat prices and cosmic ray cycle variations in the 17th Century, for which both wheat prices and cosmic ray intensity (derived from Be-10 isotope data) are available. We show that for all seven solar activity minimums (cosmic ray intensity maximums) the observed prices were higher than prices for the seven intervals of maximal solar activity (100% sign correlation). This result, combined with the conclusion of similarity of statistical properties of the price and solar activity extremes can be considered as direct evidence of a causal connection between wheat prices bursts and solar activity/cosmic ray intensity extremes.

Understanding Statistical Variation: A Response to Sharma

ERIC Educational Resources Information Center

Farmer, Jim

2008-01-01

In this article, the author responds to the paper "Exploring pre-service teachers' understanding of statistical variation: Implications for teaching and research" by Sashi Sharma (see EJ779107). In that paper, Sharma described a study "designed to investigate pre-service teachers' acknowledgment of variation in sampling and distribution…

Does the hybrid light source (LED/laser) influence temperature variation on the enamel surface during 35% hydrogen peroxide bleaching? A randomized clinical trial.

PubMed

de Freitas, Patricia Moreira; Menezes, Andressa Nery; da Mota, Ana Carolina Costa; Simões, Alyne; Mendes, Fausto Medeiros; Lago, Andrea Dias Neves; Ferreira, Leila Soares; Ramos-Oliveira, Thayanne Monteiro

2016-01-01

The present study investigated how a hybrid light source (LED/laser) influences temperature variation on the enamel surfaces during 35% hydrogen peroxide (HP) bleaching. Effects on the whitening effectiveness and tooth sensitivity were analyzed. Twenty-two volunteers were randomly assigned to two different treatments in a split-mouth experimental model: group 1 (control), 35% HP; group 2 (experimental), 35% HP + LED/laser. Color evaluation was performed before treatment, and 7 and 14 days after completion of bleaching, using a color shade scale. Tooth sensitivity was assessed using a visual analog scale (VAS; before, immediately, and 24 hours after bleaching). During the bleaching treatment, thermocouple channels positioned on the tooth surfaces recorded the temperature. Data on color and temperature changes were subjected to statistical analysis (α = 5%). Tooth sensitivity data were evaluated descriptively. Groups 1 and 2 showed mean temperatures (± standard deviation) of 30.7 ± 1.2 °C and 34.1 ± 1.3 °C, respectively. It was found that there were statistically significant differences between the groups, with group 2 showing higher mean variation (P < .0001). The highest temperature variation occurred for group 2, with an increase of 5.3 °C at the enamel surface. The color change results showed no differences in bleaching between the two treatment groups (P = .177). The variation of the average temperature during the treatments was not statistically associated with color variation (P = .079). Immediately after bleaching, it was found that 36.4% of the subjects in group 2 had mild to moderate sensitivity. In group 1, 45.5% showed moderate sensitivity. In both groups, the sensitivity ceased within 24 hours. Hybrid light source (LED/ laser) influences temperature variation on the enamel surface during 35% HP bleaching and is not related to greater tooth sensitivity.

Governance and Regional Variation of Homicide Rates: Evidence From Cross-National Data.

PubMed

Cao, Liqun; Zhang, Yan

2017-01-01

Criminological theories of cross-national studies of homicide have underestimated the effects of quality governance of liberal democracy and region. Data sets from several sources are combined and a comprehensive model of homicide is proposed. Results of the spatial regression model, which controls for the effect of spatial autocorrelation, show that quality governance, human development, economic inequality, and ethnic heterogeneity are statistically significant in predicting homicide. In addition, regions of Latin America and non-Muslim Sub-Saharan Africa have significantly higher rates of homicides ceteris paribus while the effects of East Asian countries and Islamic societies are not statistically significant. These findings are consistent with the expectation of the new modernization and regional theories. © The Author(s) 2015.

Mapping morphological shape as a high-dimensional functional curve

PubMed Central

Fu, Guifang; Huang, Mian; Bo, Wenhao; Hao, Han; Wu, Rongling

2018-01-01

Abstract Detecting how genes regulate biological shape has become a multidisciplinary research interest because of its wide application in many disciplines. Despite its fundamental importance, the challenges of accurately extracting information from an image, statistically modeling the high-dimensional shape and meticulously locating shape quantitative trait loci (QTL) affect the progress of this research. In this article, we propose a novel integrated framework that incorporates shape analysis, statistical curve modeling and genetic mapping to detect significant QTLs regulating variation of biological shape traits. After quantifying morphological shape via a radius centroid contour approach, each shape, as a phenotype, was characterized as a high-dimensional curve, varying as angle θ runs clockwise with the first point starting from angle zero. We then modeled the dynamic trajectories of three mean curves and variation patterns as functions of θ. Our framework led to the detection of a few significant QTLs regulating the variation of leaf shape collected from a natural population of poplar, Populus szechuanica var tibetica. This population, distributed at altitudes 2000–4500 m above sea level, is an evolutionarily important plant species. This is the first work in the quantitative genetic shape mapping area that emphasizes a sense of ‘function’ instead of decomposing the shape into a few discrete principal components, as the majority of shape studies do. PMID:28062411

Complex Adaptive System Models and the Genetic Analysis of Plasma HDL-Cholesterol Concentration

PubMed Central

Rea, Thomas J.; Brown, Christine M.; Sing, Charles F.

2006-01-01

Despite remarkable advances in diagnosis and therapy, ischemic heart disease (IHD) remains a leading cause of morbidity and mortality in industrialized countries. Recent efforts to estimate the influence of genetic variation on IHD risk have focused on predicting individual plasma high-density lipoprotein cholesterol (HDL-C) concentration. Plasma HDL-C concentration (mg/dl), a quantitative risk factor for IHD, has a complex multifactorial etiology that involves the actions of many genes. Single gene variations may be necessary but are not individually sufficient to predict a statistically significant increase in risk of disease. The complexity of phenotype-genotype-environment relationships involved in determining plasma HDL-C concentration has challenged commonly held assumptions about genetic causation and has led to the question of which combination of variations, in which subset of genes, in which environmental strata of a particular population significantly improves our ability to predict high or low risk phenotypes. We document the limitations of inferences from genetic research based on commonly accepted biological models, consider how evidence for real-world dynamical interactions between HDL-C determinants challenges the simplifying assumptions implicit in traditional linear statistical genetic models, and conclude by considering research options for evaluating the utility of genetic information in predicting traits with complex etiologies. PMID:17146134

Variations in testosterone pathway genes and susceptibility to testicular cancer in Norwegian men.

PubMed

Kristiansen, W; Aschim, E L; Andersen, J M; Witczak, O; Fosså, S D; Haugen, T B

2012-12-01

Imbalance between the oestrogen and androgen levels in utero is hypothesized to influence testicular cancer (TC) risk. Thus, variation in genes involved in the action of sex hormones may contribute to variability of an individual's susceptibility to TC. Mutations in testosterone pathway genes may alter the level of testosterone in vivo and hypothetically the risk of developing TC. Luteinizing hormone receptor (LHR), 5α-reductase II (SRD5A2) and androgen receptor (AR) are key elements in androgen action. A case-control study comprising 651 TC cases and 313 controls in a Norwegian population was conducted for investigation of polymorphisms in the LHR, SRD5A and AR genes and their possible association with TC. A statistical significant difference was observed in patients being heterozygous for the LHR Asn312Ser polymorphism when comparing genotypes between all TC cases and controls (OR = 0.66, 95% CI = 0.48-0.89, p(adj) = 0.049). No statistically significant difference between the histological subtypes seminoma and non-seminoma was observed. Our results may suggest a possible association between genetic variation in the LHR gene and the risk of developing TC. © 2012 The Authors. International Journal of Andrology © 2012 European Academy of Andrology.

Single and Multiple Indicators of Physical Attractiveness and Psychosocial Behaviors among Young Adolescents.

ERIC Educational Resources Information Center

Perkins, Daniel F.; Lerner, Richard M.

1995-01-01

Examined relations among several indicators of physical attractiveness (PA): height, weight, and triceps skinfold thickness. Appraised whether multiple PA indicators accounted for more variation in measures of psychosocial functioning than did single PA indexes. Facial attractiveness was the most frequent statistically significant predictor of…

The effect of regional sea level atmospheric pressure on sea level variations at globally distributed tide gauge stations with long records

NASA Astrophysics Data System (ADS)

Iz, H. Bâki

2018-05-01

This study provides additional information about the impact of atmospheric pressure on sea level variations. The observed regularity in sea level atmospheric pressure depends mainly on the latitude and verified to be dominantly random closer to the equator. It was demonstrated that almost all the annual and semiannual sea level variations at 27 globally distributed tide gauge stations can be attributed to the regional/local atmospheric forcing as an inverted barometric effect. Statistically significant non-linearities were detected in the regional atmospheric pressure series, which in turn impacted other sea level variations as compounders in tandem with the lunar nodal forcing, generating lunar sub-harmonics with multidecadal periods. It was shown that random component of regional atmospheric pressure tends to cluster at monthly intervals. The clusters are likely to be caused by the intraannual seasonal atmospheric temperature changes,which may also act as random beats in generating sub-harmonics observed in sea level changes as another mechanism. This study also affirmed that there are no statistically significant secular trends in the progression of regional atmospheric pressures, hence there was no contribution to the sea level trends during the 20th century by the atmospheric pressure.Meanwhile, the estimated nonuniform scale factors of the inverted barometer effects suggest that the sea level atmospheric pressure will bias the sea level trends inferred from satellite altimetry measurements if their impact is accounted for as corrections without proper scaling.

Optimal filtering and Bayesian detection for friction-based diagnostics in machines.

PubMed

Ray, L R; Townsend, J R; Ramasubramanian, A

2001-01-01

Non-model-based diagnostic methods typically rely on measured signals that must be empirically related to process behavior or incipient faults. The difficulty in interpreting a signal that is indirectly related to the fundamental process behavior is significant. This paper presents an integrated non-model and model-based approach to detecting when process behavior varies from a proposed model. The method, which is based on nonlinear filtering combined with maximum likelihood hypothesis testing, is applicable to dynamic systems whose constitutive model is well known, and whose process inputs are poorly known. Here, the method is applied to friction estimation and diagnosis during motion control in a rotating machine. A nonlinear observer estimates friction torque in a machine from shaft angular position measurements and the known input voltage to the motor. The resulting friction torque estimate can be analyzed directly for statistical abnormalities, or it can be directly compared to friction torque outputs of an applicable friction process model in order to diagnose faults or model variations. Nonlinear estimation of friction torque provides a variable on which to apply diagnostic methods that is directly related to model variations or faults. The method is evaluated experimentally by its ability to detect normal load variations in a closed-loop controlled motor driven inertia with bearing friction and an artificially-induced external line contact. Results show an ability to detect statistically significant changes in friction characteristics induced by normal load variations over a wide range of underlying friction behaviors.

Coupled Effects of Natural and Anthropogenic Controls on Seasonal and Spatial Variations of River Water Quality during Baseflow in a Coastal Watershed of Southeast China

PubMed Central

Huang, Jinliang; Huang, Yaling; Zhang, Zhenyu

2014-01-01

Surface water samples of baseflow were collected from 20 headwater sub-watersheds which were classified into three types of watersheds (natural, urban and agricultural) in the flood, dry and transition seasons during three consecutive years (2010–2012) within a coastal watershed of Southeast China. Integrating spatial statistics with multivariate statistical techniques, river water quality variations and their interactions with natural and anthropogenic controls were examined to identify the causal factors and underlying mechanisms governing spatiotemporal patterns of water quality. Anthropogenic input related to industrial effluents and domestic wastewater, agricultural activities associated with the precipitation-induced surface runoff, and natural weathering process were identified as the potential important factors to drive the seasonal variations in stream water quality for the transition, flood and dry seasons, respectively. All water quality indicators except SRP had the highest mean concentrations in the dry and transition seasons. Anthropogenic activities and watershed characteristics led to the spatial variations in stream water quality in three types of watersheds. Concentrations of NH4 +-N, SRP, K+, CODMn, and Cl− were generally highest in urban watersheds. NO3 –N Concentration was generally highest in agricultural watersheds. Mg2+ concentration in natural watersheds was significantly higher than that in agricultural watersheds. Spatial autocorrelations analysis showed similar levels of water pollution between the neighboring sub-watersheds exhibited in the dry and transition seasons while non-point source pollution contributed to the significant variations in water quality between neighboring sub-watersheds. Spatial regression analysis showed anthropogenic controls played critical roles in variations of water quality in the JRW. Management implications were further discussed for water resource management. This research demonstrates that the coupled effects of natural and anthropogenic controls involved in watershed processes, contribute to the seasonal and spatial variation of headwater stream water quality in a coastal watershed with high spatial variability and intensive anthropogenic activities. PMID:24618771

Estimation of the geochemical threshold and its statistical significance

USGS Publications Warehouse

Miesch, A.T.

1981-01-01

A statistic is proposed for estimating the geochemical threshold and its statistical significance, or it may be used to identify a group of extreme values that can be tested for significance by other means. The statistic is the maximum gap between adjacent values in an ordered array after each gap has been adjusted for the expected frequency. The values in the ordered array are geochemical values transformed by either ln(?? - ??) or ln(?? - ??) and then standardized so that the mean is zero and the variance is unity. The expected frequency is taken from a fitted normal curve with unit area. The midpoint of an adjusted gap that exceeds the corresponding critical value may be taken as an estimate of the geochemical threshold, and the associated probability indicates the likelihood that the threshold separates two geochemical populations. The adjusted gap test may fail to identify threshold values if the variation tends to be continuous from background values to the higher values that reflect mineralized ground. However, the test will serve to identify other anomalies that may be too subtle to have been noted by other means. ?? 1981.

Crustal deformation at the terminal stage before earthquake occurrence

NASA Astrophysics Data System (ADS)

Chen, C. H.; Meng, G.; Su, X.

2016-12-01

GPS data retrieved from 300 stations in China are used in this work to study stressed areas during earthquake preparation periods. Surface deformation data are derived by using the standard method and are smoothed by a temporal moving to mitigate influence from noise. A statistical method is used to distinguish significant variations from the smoothed data. The spatial distributions comprised of those significant variations show that a diameter of a stressed area preparing earthquakes is about 3500 km for a M6 event. The deformation deduced from the significant variations is highly related with the slip direction of the fault plane determined through the focal mechanism solution of earthquakes. Although the causal mechanism of such large stressed areas with rapid changes is not fully understood, the analytical results suggest that the earthquake preparation would be one of the factors dominating the common mode error in GPS studies. Mechanisms and/or numerical models of some pre-earthquake anomalous phenomena would be reconsidered based on this novel observation.

Spatio-Temporal Patterns of Barmah Forest Virus Disease in Queensland, Australia

PubMed Central

Naish, Suchithra; Hu, Wenbiao; Mengersen, Kerrie; Tong, Shilu

2011-01-01

Background Barmah Forest virus (BFV) disease is a common and wide-spread mosquito-borne disease in Australia. This study investigated the spatio-temporal patterns of BFV disease in Queensland, Australia using geographical information system (GIS) tools and geostatistical analysis. Methods/Principal Findings We calculated the incidence rates and standardised incidence rates of BFV disease. Moran's I statistic was used to assess the spatial autocorrelation of BFV incidences. Spatial dynamics of BFV disease was examined using semi-variogram analysis. Interpolation techniques were applied to visualise and display the spatial distribution of BFV disease in statistical local areas (SLAs) throughout Queensland. Mapping of BFV disease by SLAs reveals the presence of substantial spatio-temporal variation over time. Statistically significant differences in BFV incidence rates were identified among age groups (χ2 = 7587, df = 7327,p<0.01). There was a significant positive spatial autocorrelation of BFV incidence for all four periods, with the Moran's I statistic ranging from 0.1506 to 0.2901 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the state. Conclusions/Significance This is the first study to examine spatial and temporal variation in the incidence rates of BFV disease across Queensland using GIS and geostatistics. The BFV transmission varied with age and gender, which may be due to exposure rates or behavioural risk factors. There are differences in the spatio-temporal patterns of BFV disease which may be related to local socio-ecological and environmental factors. These research findings may have implications in the BFV disease control and prevention programs in Queensland. PMID:22022430

Prevalence and correlates of tobacco use among urban adult men in India: a comparison of slum dwellers vs non-slum dwellers.

PubMed

Rooban, T; Joshua, Elizabeth; Rao, Umadevi K; Ranganathan, K

2012-01-01

Tobacco use is reported to be rampant in urban slums in developing countries. Demographical variations in tobacco use between males living in urban slums vs those living in non-slum areas in India has not been reported, and this study was undertaken to address this issue. Secondary data analysis of National Family Health Survey-3 (NFHS-3) was undertaken to study demographical variations in tobacco use between urban slum dwellers and non-slum dwellers in eight Indian cities. Demographic determinants for use of smoking and chewing forms of tobacco in the two groups were analyzed. SPSS version 16.0 (SPSS Inc., IL, USA) was used for statistical analysis. The study population comprised 6887 (41.8%) males from slum areas and 9588 (58.2%) from non-slum areas of eight urban cities. Cigarette/beedi smoking was the commonest form of tobacco use among the study population. Pan masala use was the least common form of smokeless tobacco use, next only to snuff. There was a high statistical significance observed within the various demographic parameter studied in both the slum and non-slum dwelling males in study population. However, on studying the differences between the two groups, it was observed that statistical significance of P≤.001 was observed with age (15-49), secondary education, religion, household structure and marital status. The difference between the two groups in the mean number of cigarettes/beedis smoked was not statistically significant (P=.598). Male slum dwellers are a distinct urban population, whose health needs assessment requires a different approach than that for non-slum dwellers who often can afford the services that an urban Indian city can offer.

Inter-Ethnic/Racial Facial Variations: A Systematic Review and Bayesian Meta-Analysis of Photogrammetric Studies

PubMed Central

Wen, Yi Feng; Wong, Hai Ming; Lin, Ruitao; Yin, Guosheng; McGrath, Colman

2015-01-01

Background Numerous facial photogrammetric studies have been published around the world. We aimed to critically review these studies so as to establish population norms for various angular and linear facial measurements; and to determine inter-ethnic/racial facial variations. Methods and Findings A comprehensive and systematic search of PubMed, ISI Web of Science, Embase, and Scopus was conducted to identify facial photogrammetric studies published before December, 2014. Subjects of eligible studies were either Africans, Asians or Caucasians. A Bayesian hierarchical random effects model was developed to estimate posterior means and 95% credible intervals (CrI) for each measurement by ethnicity/race. Linear contrasts were constructed to explore inter-ethnic/racial facial variations. We identified 38 eligible studies reporting 11 angular and 18 linear facial measurements. Risk of bias of the studies ranged from 0.06 to 0.66. At the significance level of 0.05, African males were found to have smaller nasofrontal angle (posterior mean difference: 8.1°, 95% CrI: 2.2°–13.5°) compared to Caucasian males and larger nasofacial angle (7.4°, 0.1°–13.2°) compared to Asian males. Nasolabial angle was more obtuse in Caucasian females than in African (17.4°, 0.2°–35.3°) and Asian (9.1°, 0.4°–17.3°) females. Additional inter-ethnic/racial variations were revealed when the level of statistical significance was set at 0.10. Conclusions A comprehensive database for angular and linear facial measurements was established from existing studies using the statistical model and inter-ethnic/racial variations of facial features were observed. The results have implications for clinical practice and highlight the need and value for high quality photogrammetric studies. PMID:26247212

Adjusting for geographic variation in observational comparative effectiveness studies: a case study of antipsychotics using state Medicaid data.

PubMed

Root, Elisabeth Dowling; Thomas, Deborah S K; Campagna, Elizabeth J; Morrato, Elaine H

2014-08-27

Area-level variation in treatment and outcomes may be a potential source of confounding bias in observational comparative effectiveness studies. This paper demonstrates how to use exploratory spatial data analysis (ESDA) and spatial statistical methods to investigate and control for these potential biases. The case presented compares the effectiveness of two antipsychotic treatment strategies: oral second-generation antipsychotics (SGAs) vs. long-acting paliperiodone palmitate (PP). A new-start cohort study was conducted analyzing patient-level administrative claims data (8/1/2008-4/30/2011) from Missouri Medicaid. ESDA techniques were used to examine spatial patterns of antipsychotic prescriptions and outcomes (hospitalization and emergency department (ED) visits). Likelihood of mental health-related outcomes were compared between patients starting PP (N = 295) and oral SGAs (N = 8,626) using multilevel logistic regression models adjusting for patient composition (demographic and clinical factors) and geographic region. ESDA indicated significant spatial variation in antipsychotic prescription patterns and moderate variation in hospitalization and ED visits thereby indicating possible confounding by geography. In the multilevel models for this antipsychotic case example, patient composition represented a stronger source of confounding than geographic context. Because geographic variation in health care delivery is ubiquitous, it could be a comparative effectiveness research (CER) best practice to test for possible geographic confounding in observational data. Though the magnitude of the area-level geography effects were small in this case, they were still statistically significant and should therefore be examined as part of this observational CER study. More research is needed to better estimate the range of confounding due to geography across different types of observational comparative effectiveness studies and healthcare utilization outcomes.

Inter-Ethnic/Racial Facial Variations: A Systematic Review and Bayesian Meta-Analysis of Photogrammetric Studies.

PubMed

Wen, Yi Feng; Wong, Hai Ming; Lin, Ruitao; Yin, Guosheng; McGrath, Colman

2015-01-01

Numerous facial photogrammetric studies have been published around the world. We aimed to critically review these studies so as to establish population norms for various angular and linear facial measurements; and to determine inter-ethnic/racial facial variations. A comprehensive and systematic search of PubMed, ISI Web of Science, Embase, and Scopus was conducted to identify facial photogrammetric studies published before December, 2014. Subjects of eligible studies were either Africans, Asians or Caucasians. A Bayesian hierarchical random effects model was developed to estimate posterior means and 95% credible intervals (CrI) for each measurement by ethnicity/race. Linear contrasts were constructed to explore inter-ethnic/racial facial variations. We identified 38 eligible studies reporting 11 angular and 18 linear facial measurements. Risk of bias of the studies ranged from 0.06 to 0.66. At the significance level of 0.05, African males were found to have smaller nasofrontal angle (posterior mean difference: 8.1°, 95% CrI: 2.2°-13.5°) compared to Caucasian males and larger nasofacial angle (7.4°, 0.1°-13.2°) compared to Asian males. Nasolabial angle was more obtuse in Caucasian females than in African (17.4°, 0.2°-35.3°) and Asian (9.1°, 0.4°-17.3°) females. Additional inter-ethnic/racial variations were revealed when the level of statistical significance was set at 0.10. A comprehensive database for angular and linear facial measurements was established from existing studies using the statistical model and inter-ethnic/racial variations of facial features were observed. The results have implications for clinical practice and highlight the need and value for high quality photogrammetric studies.

Genetic variation in the raptor gene is associated with overweight but not hypertension in American men of Japanese ancestry.

PubMed

Morris, Brian J; Carnes, Bruce A; Chen, Randi; Donlon, Timothy A; He, Qimei; Grove, John S; Masaki, Kamal H; Elliott, Ayako; Willcox, Donald C; Allsopp, Richard; Willcox, Bradley J

2015-04-01

The mechanistic target of rapamycin (mTOR) pathway is pivotal for cell growth. Regulatory associated protein of mTOR complex I (Raptor) is a unique component of this pro-growth complex. The present study tested whether variation across the raptor gene (RPTOR) is associated with overweight and hypertension. We tested 61 common (allele frequency ≥ 0.1) tagging single nucleotide polymorphisms (SNPs) that captured most of the genetic variation across RPTOR in 374 subjects of normal lifespan and 439 subjects with a lifespan exceeding 95 years for association with overweight/obesity, essential hypertension, and isolated systolic hypertension. Subjects were drawn from the Honolulu Heart Program, a homogeneous population of American men of Japanese ancestry, well characterized for phenotypes relevant to conditions of aging. Hypertension status was ascertained when subjects were 45-68 years old. Statistical evaluation involved contingency table analysis, logistic regression, and the powerful method of recursive partitioning. After analysis of RPTOR genotypes by each statistical approach, we found no significant association between genetic variation in RPTOR and either essential hypertension or isolated systolic hypertension. Models generated by recursive partitioning analysis showed that RPTOR SNPs significantly enhanced the ability of the model to accurately assign individuals to either the overweight/obese or the non-overweight/obese groups (P = 0.008 by 1-tailed Z test). Common genetic variation in RPTOR is associated with overweight/obesity but does not discernibly contribute to either essential hypertension or isolated systolic hypertension in the population studied. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Earth tides, volcanos and climatic change

NASA Technical Reports Server (NTRS)

Roosen, R. G.; Harrington, R. S.; Giles, J.; Browning, I.

1976-01-01

The effect of variations in tidal stresses on the earth caused by the sun and moon on volcanic activity and climate is investigated. A statistically significant correlation is found between the derivatives of the envelopes of peak tidal stresses at high northern latitudes and the mean temperature of the Northern Hemisphere as reflected in oxygen isotope ratios in the Greenland ice cap. It is suggested that variations in tidal stresses cause changes in the amount of stratospheric dust produced by volcanic activity, which affects the thickness of the stratospheric dust veil and the atmospheric radiation balance. For a simple model, periodic variations in tidal stress account for 13% of the variance in the ice-core temperature record.

Clan-structured migration and phenotypic differentiation in the Jirels of Nepal.

PubMed

Williams-Blangero, S

1989-04-01

This paper examines the impact of clan-structured migration on the between-village differentiation of the Jirels, a tribal population of eastern Nepal. The Jirel population is geographically restricted to nine villages, all of which were sampled to some extent for this study. Data on five head measurements, stature, and digital ridge counts are utilized to illustrate the patterns of phenotypic variation. Multivariate statistical techniques are used to assess the extent to which clan membership and associated patterns of marital exchange influence the population structure of the Jirels. The phenotypic characteristics of randomly generated migrant sets are compared to those of the observed clan-structured sets, demonstrating the clan-related phenotypic nonrandomness of migrants. The results indicate that clan-structured migration may significantly influence the amount of between-village variation. Clan structure may be a significant factor in determining patterns of variation and should not be ignored in studies of microdifferentiation in tribal populations.

Brightness Variations in the Solar Atmosphere as Seen by SOHO

NASA Astrophysics Data System (ADS)

Brkovic, A.; Rüedi, I.; Solanki, S. K.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.; Harrison, R.; Fludra, A.

We present preliminary results of a statistical analysis of the brightness variations of solar features at different levels in the solar atmosphere. We observed quiet Sun regions at disc centre using the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and Heliospheric Observatory (SOHO). We find significant variability at all time scales in all parts of the quiet Sun, from darkest intranetwork to brightest network. Such variations are observed simultaneously in the chromospheric He I 584.33 Angstroms (2 \\cdot 10^4 K) line, the transition region O V 629.74 Angstroms (2.5 \\cdot 10^5 K) and coronal Mg IX 368.06 Angstroms (10^6 K) line. The relative variability is independent of brightness and most of the variability appears to take place on time scales longer than 5 minutes for all 3 spectral lines. No significant differences are observed between the different data sets.

How reliable is computerized assessment of readability?

PubMed

Mailloux, S L; Johnson, M E; Fisher, D G; Pettibone, T J

1995-01-01

To assess the consistency and comparability of readability software programs, four software programs (Corporate Voice, Grammatix IV, Microsoft Word for Windows, and RightWriter) were compared. Standard materials included 28 pieces of printed educational materials on human immunodeficiency virus/acquired immunodeficiency syndrome distributed nationally and the Gettysburg Address. Statistical analyses for the educational materials revealed that each of the three formulas assessed (Flesch-Kincaid, Flesch Reading Ease, and Gunning Fog Index) provided significantly different grade equivalent scores and that the Microsoft Word program provided significantly lower grade levels and was more inconsistent in the scores provided. For the Gettysburg Address, considerable variation was revealed among formulas, with the discrepancy being up to two grade levels. When averaging across formulas, there was a variation of 1.3 grade levels between the four software programs. Given the variation between formulas and programs, implications for decisions based on results of these software programs are provided.

Trends in Birth Rates: New York City 1970-1995.

ERIC Educational Resources Information Center

Finkel, Madelon L.; Elkin, Elena

2001-01-01

Examined teen birth rates in New York City health districts over 25 years, noting ethnic variations. Data from Department of Health vital statistics indicated that the decline in the birth rate among New York City teens was most significant in health districts populated predominantly by blacks. There were substantial decreases among older teens…

SUNLIGHT AS A FACTOR INFLUENCING THE THICKNESS OF EPIDERMIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, R.G.; Cockerell, E.G.; Armstrong, J.

Measurements of epidermal thickness were made on 28 human volunteers. Shortening of rete ridges was found in exposed white skin but was not seen in unexposed skin nor in Negroes. Differences in epidermal thickness related to age, sex, complexion, or variation in sunlight exposure were not statistically significant. (P.C.H.)

Serum erythropoietin levels in patients with central serous chorioretinopathy

PubMed Central

Turgut, Burak; Ilhan, Nevin; Uyar, Fatma Yayla; Celiker, Ulku; Demir, Tamer; Koca, Suleyman Serdar

2010-01-01

Objective To evaluate the levels of erythropoietin (EPO) in the serum in patients with central serous chorioretinopathy (CSC). Methods An institutional comperative clinical study. The serum EPO levels were measured with the enzyme-linked immunosorbent assay (ELISA) method, of 15 patients with active CSC (Group 1), 15 patients with inactive CSC (Group 2) and 15 healthy volunteers (Group 3). Kruskal–Wallis variance analysis and Mann–Whitney U test were used for statistical analysis. Results The patient and control groups were matched for age and sex. There was no statistically significant variation with regard to age and gender among the groups (P > 0.05). The mean serum EPO concentrations in patients with active CSC (Group 1), inactive CSC (Group 2) and in healthy controls (Group 3) were 11.39 ± 3.01 mlU/mL, 11.79 ± 3.78 mlU/mL and 11.95 ± 3.27 mlU/mL, respectively. There was no significant variation among the serum EPO concentrations of the study groups (P > 0.05). Conclusion These findings suggest no role of serum EPO in pathogenesis of CSC. PMID:28539767

Serum erythropoietin levels in patients with central serous chorioretinopathy.

PubMed

Turgut, Burak; Ilhan, Nevin; Uyar, Fatma Yayla; Celiker, Ulku; Demir, Tamer; Koca, Suleyman Serdar

2010-01-01

To evaluate the levels of erythropoietin (EPO) in the serum in patients with central serous chorioretinopathy (CSC). An institutional comperative clinical study. The serum EPO levels were measured with the enzyme-linked immunosorbent assay (ELISA) method, of 15 patients with active CSC (Group 1), 15 patients with inactive CSC (Group 2) and 15 healthy volunteers (Group 3). Kruskal-Wallis variance analysis and Mann-Whitney U test were used for statistical analysis. The patient and control groups were matched for age and sex. There was no statistically significant variation with regard to age and gender among the groups ( P > 0.05). The mean serum EPO concentrations in patients with active CSC (Group 1), inactive CSC (Group 2) and in healthy controls (Group 3) were 11.39 ± 3.01 mlU/mL, 11.79 ± 3.78 mlU/mL and 11.95 ± 3.27 mlU/mL, respectively. There was no significant variation among the serum EPO concentrations of the study groups ( P > 0.05). These findings suggest no role of serum EPO in pathogenesis of CSC.

Similarity in temperament between mother and offspring rhesus monkeys: Sex differences and the role of monoamine oxidase-A and serotonin transporter promoter polymorphism genotypes

PubMed Central

Sullivan, Erin C.; Mendoza, Sally P.; Capitanio, John P.

2011-01-01

Temperament is usually considered biologically based and largely inherited, however the environment can shape the development of temperament. Allelic variation may confer differential sensitivity to early environment resulting in variations in temperament. Here we explore the relationship between measures of temperament in mothers and their first-born offspring and the role of genetic sensitivity in establishing the strength of these associations. Temperament ratings were conducted on 3-4 month old rhesus monkeys after a 25-hour biobehavioral assessment. Factor analysis revealed a four factor structure of temperament. Females assessed as infants have reproduced and their offspring have also been evaluated through the standardized testing paradigm. Canonical correlation analysis revealed statistically significant associations between factor scores of mothers and sons, but not mothers and daughters. Further, offspring possessing the high activity, “low risk”, alleles of the rhMAOA-LPR or rh5-HTTLPR showed statistically significant canonical correlations, whereas those possessing other alleles did not, suggesting differential genetic sensitivity to the normative early experience of maternal temperament. PMID:21866539

Trophic classification of Tennessee Valley area reservoirs derived from LANDSAT multispectral scanner data. [Alabama, Georgia, Kentucky, Tennessee, and North Carolina

NASA Technical Reports Server (NTRS)

Meinert, D. L.; Malone, D. L.; Voss, A. W. (Principal Investigator); Scarpace, F. L.

1980-01-01

LANDSAT MSS data from four different dates were extracted from computer tapes using a semiautomated digital data handling and analysis system. Reservoirs were extracted from the surrounding land matrix by using a Band 7 density level slice of 3; and descriptive statistics to include mean, variance, and ratio between bands for each of the four bands were calculated. Significant correlations ( 0.80) were identified between the MSS statistics and many trophic indicators from ground truth water quality data collected at 35 reservoirs in the greater Tennessee Valley region. Regression models were developed which gave significant estimates of each reservoir's trophic state as defined by its trophic state index and explained in all four LANDSAT frames at least 85 percent of the variability in the data. To illustrate the spatial variations within reservoirs as well as the relative variations between reservoirs, a table look up elliptical classification was used in conjunction with each reservoir's trophic state index to classify each reservoir on a pixel by pixel basis and produce color coded thematic representations.

Analysis of pediatric blood lead levels in New York City for 1970-1976.

PubMed Central

Billick, I H; Curran, A S; Shier, D R

1979-01-01

A study was completed of more than 170,000 records of pediatric venous blood levels and supporting demographic information collected in New York City during 1970-1976. The geometric mean (GM) blood lead level shows a consistent cyclical variation superimposed on an overall decreasing trend with time for all ages and ethnic groups studied. The GM blood lead levels for blacks are significantly greater than those for either Hispanics or whites. Regression analysis indicates a significant statistical association between GM blood lead level and ambient air lead level, after appropriate adjustments are made for age and ethnic group. These highly significant statistical relationships provide extremely strong incentives and directions for research into casual factors related to blood lead levels in children. PMID:499123

Variations in intensity statistics for representational and abstract art, and for art from the Eastern and Western hemispheres.

PubMed

Graham, Daniel J; Field, David J

2008-01-01

Two recent studies suggest that natural scenes and paintings show similar statistical properties. But does the content or region of origin of an artwork affect its statistical properties? We addressed this question by having judges place paintings from a large, diverse collection of paintings into one of three subject-matter categories using a forced-choice paradigm. Basic statistics for images whose caterogization was agreed by all judges showed no significant differences between those judged to be 'landscape' and 'portrait/still-life', but these two classes differed from paintings judged to be 'abstract'. All categories showed basic spatial statistical regularities similar to those typical of natural scenes. A test of the full painting collection (140 images) with respect to the works' place of origin (provenance) showed significant differences between Eastern works and Western ones, differences which we find are likely related to the materials and the choice of background color. Although artists deviate slightly from reproducing natural statistics in abstract art (compared to representational art), the great majority of human art likely shares basic statistical limitations. We argue that statistical regularities in art are rooted in the need to make art visible to the eye, not in the inherent aesthetic value of natural-scene statistics, and we suggest that variability in spatial statistics may be generally imposed by manufacture.

Research on the optimization of air quality monitoring station layout based on spatial grid statistical analysis method.

PubMed

Li, Tianxin; Zhou, Xing Chen; Ikhumhen, Harrison Odion; Difei, An

2018-05-01

In recent years, with the significant increase in urban development, it has become necessary to optimize the current air monitoring stations to reflect the quality of air in the environment. Highlighting the spatial representation of some air monitoring stations using Beijing's regional air monitoring station data from 2012 to 2014, the monthly mean particulate matter concentration (PM10) in the region was calculated and through the IDW interpolation method and spatial grid statistical method using GIS, the spatial distribution of PM10 concentration in the whole region was deduced. The spatial distribution variation of districts in Beijing using the gridding model was performed, and through the 3-year spatial analysis, PM10 concentration data including the variation and spatial overlay (1.5 km × 1.5 km cell resolution grid), the spatial distribution result obtained showed that the total PM10 concentration frequency variation exceeded the standard. It is very important to optimize the layout of the existing air monitoring stations by combining the concentration distribution of air pollutants with the spatial region using GIS.

Note onset deviations as musical piece signatures.

PubMed

Serrà, Joan; Özaslan, Tan Hakan; Arcos, Josep Lluis

2013-01-01

A competent interpretation of a musical composition presents several non-explicit departures from the written score. Timing variations are perhaps the most important ones: they are fundamental for expressive performance and a key ingredient for conferring a human-like quality to machine-based music renditions. However, the nature of such variations is still an open research question, with diverse theories that indicate a multi-dimensional phenomenon. In the present study, we consider event-shift timing variations and show that sequences of note onset deviations are robust and reliable predictors of the musical piece being played, irrespective of the performer. In fact, our results suggest that only a few consecutive onset deviations are already enough to identify a musical composition with statistically significant accuracy. We consider a mid-size collection of commercial recordings of classical guitar pieces and follow a quantitative approach based on the combination of standard statistical tools and machine learning techniques with the semi-automatic estimation of onset deviations. Besides the reported results, we believe that the considered materials and the methodology followed widen the testing ground for studying musical timing and could open new perspectives in related research fields.

Complication rates of ostomy surgery are high and vary significantly between hospitals.

PubMed

Sheetz, Kyle H; Waits, Seth A; Krell, Robert W; Morris, Arden M; Englesbe, Michael J; Mullard, Andrew; Campbell, Darrell A; Hendren, Samantha

2014-05-01

Ostomy surgery is common and has traditionally been associated with high rates of morbidity and mortality, suggesting an important target for quality improvement. The purpose of this work was to evaluate the variation in outcomes after ostomy creation surgery within Michigan to identify targets for quality improvement. This was a retrospective cohort study. The study took place within the 34-hospital Michigan Surgical Quality Collaborative. Patients included were those undergoing ostomy creation surgery between 2006 and 2011. We evaluated hospital morbidity and mortality rates after risk adjustment (age, comorbidities, emergency vs elective, and procedure type). A total of 4250 patients underwent ostomy creation surgery; 3866 procedures (91.0%) were open and 384 (9.0%) were laparoscopic. Unadjusted morbidity and mortality rates were 43.9% and 10.7%. Unadjusted morbidity rates for specific procedures ranged from 32.7% for ostomy-creation-only procedures to 47.8% for Hartmann procedures. Risk-adjusted morbidity rates varied significantly between hospitals, ranging from 31.2% (95% CI, 18.4-43.9) to 60.8% (95% CI, 48.9-72.6). There were 5 statistically significant high-outlier hospitals and 3 statistically significant low-outlier hospitals for risk-adjusted morbidity. The pattern of complication types was similar between high- and low-outlier hospitals. Case volume, operative duration, and use of laparoscopic surgery did not explain the variation in morbidity rates across hospitals. This work was limited by its retrospective study design, by unmeasured variation in case severity, and by our inability to differentiate between colostomies and ileostomies because of the use of Current Procedural Terminology codes. Morbidity and mortality rates for modern ostomy surgery are high. Although this type of surgery has received little attention in healthcare policy, these data reveal that it is both common and uncommonly morbid. Variation in hospital performance provides an opportunity to identify quality improvement practices that could be disseminated among hospitals.

Acceleration techniques for dependability simulation. M.S. Thesis

NASA Technical Reports Server (NTRS)

Barnette, James David

1995-01-01

As computer systems increase in complexity, the need to project system performance from the earliest design and development stages increases. We have to employ simulation for detailed dependability studies of large systems. However, as the complexity of the simulation model increases, the time required to obtain statistically significant results also increases. This paper discusses an approach that is application independent and can be readily applied to any process-based simulation model. Topics include background on classical discrete event simulation and techniques for random variate generation and statistics gathering to support simulation.

Exploring Pre-Service Teachers' Understanding of Statistical Variation: Implications for Teaching and Research

ERIC Educational Resources Information Center

Sharma, Sashi

2007-01-01

Concerns about the importance of variation in statistics education and a lack of research in this topic led to a preliminary study which explored pre-service teachers' ideas in this area. The teachers completed a written questionnaire about variation in sampling and distribution contexts. Responses were categorised in relation to a framework that…

Direct and indirect influence of parental bedrock on streambed microbial community structure in forested streams.

PubMed

Mosher, Jennifer J; Findlay, Robert H

2011-11-01

A correlative study was performed to determine if variation in streambed microbial community structure in low-order forested streams can be directly or indirectly linked to the chemical nature of the parental bedrock of the environments through which the streams flow. Total microbial and photosynthetic biomass (phospholipid phosphate [PLP] and chlorophyll a), community structure (phospholipid fatty acid analysis), and physical and chemical parameters were measured in six streams, three located in sandstone and three in limestone regions of the Bankhead National Forest in northern Alabama. Although stream water flowing through the two different bedrock types differed significantly in chemical composition, there were no significant differences in total microbial and photosynthetic biomass in the sediments. In contrast, sedimentary microbial community structure differed between the bedrock types and was significantly correlated with stream water ion concentrations. A pattern of seasonal variation in microbial community structure was also observed. Further statistical analysis indicated dissolved organic matter (DOM) quality, which was previously shown to be influenced by geological variation, correlated with variation in bacterial community structure. These results indicate that the geology of underlying bedrock influences benthic microbial communities directly via changes in water chemistry and also indirectly via stream water DOM quality.

Calculating stage duration statistics in multistage diseases.

PubMed

Komarova, Natalia L; Thalhauser, Craig J

2011-01-01

Many human diseases are characterized by multiple stages of progression. While the typical sequence of disease progression can be identified, there may be large individual variations among patients. Identifying mean stage durations and their variations is critical for statistical hypothesis testing needed to determine if treatment is having a significant effect on the progression, or if a new therapy is showing a delay of progression through a multistage disease. In this paper we focus on two methods for extracting stage duration statistics from longitudinal datasets: an extension of the linear regression technique, and a counting algorithm. Both are non-iterative, non-parametric and computationally cheap methods, which makes them invaluable tools for studying the epidemiology of diseases, with a goal of identifying different patterns of progression by using bioinformatics methodologies. Here we show that the regression method performs well for calculating the mean stage durations under a wide variety of assumptions, however, its generalization to variance calculations fails under realistic assumptions about the data collection procedure. On the other hand, the counting method yields reliable estimations for both means and variances of stage durations. Applications to Alzheimer disease progression are discussed.

A powerful and flexible statistical framework for testing hypotheses of allele-specific gene expression from RNA-seq data

PubMed Central

Skelly, Daniel A.; Johansson, Marnie; Madeoy, Jennifer; Wakefield, Jon; Akey, Joshua M.

2011-01-01

Variation in gene expression is thought to make a significant contribution to phenotypic diversity among individuals within populations. Although high-throughput cDNA sequencing offers a unique opportunity to delineate the genome-wide architecture of regulatory variation, new statistical methods need to be developed to capitalize on the wealth of information contained in RNA-seq data sets. To this end, we developed a powerful and flexible hierarchical Bayesian model that combines information across loci to allow both global and locus-specific inferences about allele-specific expression (ASE). We applied our methodology to a large RNA-seq data set obtained in a diploid hybrid of two diverse Saccharomyces cerevisiae strains, as well as to RNA-seq data from an individual human genome. Our statistical framework accurately quantifies levels of ASE with specified false-discovery rates, achieving high reproducibility between independent sequencing platforms. We pinpoint loci that show unusual and biologically interesting patterns of ASE, including allele-specific alternative splicing and transcription termination sites. Our methodology provides a rigorous, quantitative, and high-resolution tool for profiling ASE across whole genomes. PMID:21873452

Effects of population succession on demographic and genetic processes: predictions and tests in the daylily Hemerocallis thunbergii (Liliaceae).

PubMed

Chung, Mi Yoon; Nason, John D; Chung, Myong Gi

2007-07-01

Spatial genetic structure within plant populations is influenced by variation in demographic processes through space and time, including a population's successional status. To determine how demographic structure and fine-scale genetic structure (FSGS) change with stages in a population's successional history, we studied Hemerocallis thunbergii (Liliaceae), a nocturnal flowering and hawkmoth-pollinated herbaceous perennial with rapid population turnover dynamics. We examined nine populations assigned to three successive stages of population succession: expansion, maturation, and senescence. We developed stage-specific expectations for within-population demographic and genetic structure, and then for each population quantified the spatial aggregation of individuals and genotypes using spatial autocorrelation methods (nonaccumulative O-ring and kinship statistics, respectively), and at the landscape level measured inbreeding and genetic structure using Wright's F-statistics. Analyses using the O-ring statistic revealed significant aggregation of individuals at short spatial scales in expanding and senescing populations, in particular, which may reflect restricted seed dispersal around maternal individuals combined with relatively low local population densities at these stages. Significant FSGS was found for three of four expanding, no mature, and only one senescing population, a pattern generally consistent with expectations of successional processes. Although allozyme genetic diversity was high within populations (mean %P = 78.9 and H(E) = 0.281), landscape-level differentiation among sites was also high (F(ST) = 0.166) and all populations exhibited a significant deficit of heterozygotes relative to Hardy-Weinberg expectations (range F = 0.201-0.424, mean F(IS) = 0.321). Within populations, F was not correlated with the degree of FSGS, thus suggesting inbreeding due primarily to selfing as opposed to mating among close relatives in spatially structured populations. Our results demonstrate considerable variation in the spatial distribution of individuals and patterns and magnitude of FSGS in H. thunbergii populations across the landscape. This variation is generally consistent with succession-stage-specific differences in ecological processes operating within these populations.

Factors associated with emergency medical services scope of practice for acute cardiovascular events.

PubMed

Williams, Ishmael; Valderrama, Amy L; Bolton, Patricia; Greek, April; Greer, Sophia; Patterson, Davis G; Zhang, Zefeng

2012-01-01

To examine prehospital emergency medical services (EMS) scope of practice for acute cardiovascular events and characteristics that may affect scope of practice; and to describe variations in EMS scope of practice for these events and the characteristics associated with that variability. In 2008, we conducted a telephone survey of 1,939 eligible EMS providers in nine states to measure EMS agency characteristics, medical director involvement, and 18 interventions authorized for prehospital care of acute cardiovascular events by three levels of emergency medical technician (EMT) personnel. A total of 1,292 providers responded to the survey, for a response rate of 67%. EMS scope of practice interventions varied by EMT personnel level, with the proportion of authorized interventions increasing as expected from EMT-Basic to EMT-Paramedic. Seven of eight statistically significant associations indicated that EMS agencies in urban settings were less likely to authorize interventions (odds ratios <0.7) for any level of EMS personnel. Based on the subset of six statistically significant associations, fire department-based EMS agencies were two to three times more likely to authorize interventions for EMT-Intermediate personnel. Volunteer EMS agencies were more than twice as likely as nonvolunteer agencies to authorize interventions for EMT-Basic and EMT-Intermediate personnel but were less likely to authorize any one of the 11 interventions for EMT-Paramedics. Greater medical director involvement was associated with greater likelihood of authorization of seven of the 18 interventions for EMT-Basic and EMT-Paramedic personnel but had no association with EMT-Intermediate personnel. We noted statistically significant variations in scope of practice by rural vs. urban setting, medical director involvement, and type of EMS service (fire department-based/non-fire department-based; volunteer/paid). These variations highlight local differences in the composition and capacity of EMS providers and offer important information for the transition towards the implementation of a national scope of practice model.

Practice variation in the transfer of premature infants from incubators to open cots in Australian and New Zealand neonatal nurseries: results of an electronic survey.

PubMed

New, Karen; Bogossian, Fiona; East, Christine; Davies, Mark William

2010-06-01

The incubator environment is essential for optimal physiological functioning and development of the premature infant but the infant is ultimately required to make a successful transfer from incubator to open cot in order to be discharged from hospital. Criteria for transfer lack a systematic approach because no clear, specific guideline predominates in clinical practice. Practice variation exists between continents, regions and nurseries in the same countries, but there is no recent review of current practices utilised for transferring premature infants from incubators to open cots. To document current practice for transferring premature infants to open cots in neonatal nurseries. A descriptive, cross-sectional survey. Twenty-two neonatal intensive care units and fifty-six high dependency special care baby units located in public hospitals in Australia and New Zealand. A sample of 78 key clinical nursing leaders (nurse unit managers, clinical nurse consultants or clinical nurse specialists) within neonatal nurseries identified through email or telephone contact. Data were collected using a web-based survey on practice, decision-making and strategies utilised for transferring premature infants from incubators to open cots. Descriptive statistics (frequencies and crosstabs) were used to analyse data. Comparisons between groups were tested for statistical significance using Chi-squared or Fisher's exact test. Significant practice variation between countries was found for only one variable, nursing infants clothed (p=0.011). Processes and practices undertaken similarly in both countries include use of incubator air control mode, current weight criterion, thermal challenging, single-walled incubators and heated mattress systems. Practice variation was significant between neonatal intensive care units and special care baby units for weight range (p=0.005), evidence-based practice (p=0.004), historical nursery practice (p=0.029) and incubator air control mode (p=0.001). Differences in these variables were also found between nurseries in metropolitan and rural locations. Practice variation exists however; many practices are uniformly performed throughout neonatal nurseries in Australian and New Zealand. Commonality was seen between countries and in nurseries with a neonatal intensive care unit. Variation was significant between neonatal intensive care units and special care baby units and nurseries in metropolitan and rural locations. (c) 2009 Elsevier Ltd. All rights reserved.

Atmospheric mercury measurements at a suburban site in the Mid-Atlantic United States: Inter-annual, seasonal and diurnal variations and source-receptor relationships

NASA Astrophysics Data System (ADS)

Ren, Xinrong; Luke, Winston T.; Kelley, Paul; Cohen, Mark D.; Artz, Richard; Olson, Mark L.; Schmeltz, David; Puchalski, Melissa; Goldberg, Daniel L.; Ring, Allison; Mazzuca, Gina M.; Cummings, Kristin A.; Wojdan, Lisa; Preaux, Sandra; Stehr, Jeff W.

2016-12-01

Different atmospheric mercury forms have been measured at a suburban site in Beltsville, Maryland in the Mid-Atlantic United States since 2007 to investigate their inter-annual, seasonal and diurnal variabilities. Average concentrations and standard deviations of hourly measurements from 2007 to 2015 were 1.41 ± 0.23 ng m-3 for gaseous elemental mercury (GEM), 4.6 ± 33.7 pg m-3 for gaseous oxidized mercury (GOM), and 8.6 ± 56.8 pg m-3 for particulate-bound mercury (PBM). Observations show that on average, the rates of decrease were 0.020 ± 0.007 ng m-3 yr-1 (or 1.3 ± 0.5% yr-1, statistically significant, p-value < 0.01) for GEM, 0.54 ± 0.19 pg m-3 yr-1 (or 7.3 ± 2.6% yr-1, statistically significant, p-value < 0.01) for GOM, and 0.15 ± 0.35 pg m-3 yr-1 (or 1.6 ± 3.8% yr-1, statistically insignificant, p-value > 0.01) for PBM over this nine-year period. In addition, the collocated annual mercury wet deposition decreased at a rate of 0.51 ± 0.24 μg m-2 yr-2 (or 4.2 ± 1.9% yr-1, statistically insignificant, p-value > 0.01). Diurnal variation of GEM shows a slight peak in the morning, likely due to the shallow boundary layer. Seasonal variation of GEM shows lower levels in fall. Both diurnal variations of GOM and PBM show peaks in the afternoon likely due to the photochemical production of reactive mercury from the oxidation of GEM and the influence of boundary layer processes. Seasonally, GOM measurements show high levels in spring and constant low levels in the other three seasons, while PBM measurements exhibit higher levels from late fall to early spring and lower levels from late spring to fall. These measurement data were analyzed using the HYSPLIT back trajectory model in order to examine possible source-receptor relationships at this suburban site. Trajectory frequency analysis shows that high GEM/GOM/PBM events were generally associated with high frequencies of the trajectories passing through areas with high mercury emissions, while low GEM/GOM/PBM levels were largely associated the trajectories passing through relatively clean areas. This study indicates that local and regional sources appear to have a significant impact on the site and these impacts appear to have changed over time, as the local/regional emissions have been reduced.

The ecological variations in thermal infrared emissivity of vegetation. [in Texas, Arizona, New Mexico, and Mexico

NASA Technical Reports Server (NTRS)

Arp, G. K.; Phinney, D. E. (Principal Investigator)

1979-01-01

The author has identified the following significant results. Through a series of contrasts, the statistical significance of differences in emissivity was determined for vegegation in dry and humid deserts, montane and deciduous rain forests, and the temperate region. No significant differences were found between the two types of desert vegetation or among the types of nondesert vegetation. However, the rain forest vegetation was significantly different from that of the temperate region. On a community-wide level, there is some physiological adaptation in plants to their radiational environment.

Bone shape difference between control and osteochondral defect groups of the ankle joint.

PubMed

Tümer, N; Blankevoort, L; van de Giessen, M; Terra, M P; de Jong, P A; Weinans, H; Tuijthof, G J M; Zadpoor, A A

2016-12-01

The etiology of osteochondral defects (OCDs), for which the ankle (talocrural) joint is one of the common sites, is not yet fully understood. In this study, we hypothesized that bone shape plays a role in development of OCDs. Therefore, we quantitatively compared the morphology of the talus and the distal tibia between an OCD group and a control group. The shape variations of the talus and distal tibia were described separately by constructing two statistical shape models (SSMs) based on the segmentation of the bones from ankle computed tomography (CT) scans obtained from control (i.e., 35 CT scans) and OCD (i.e., 37 CT scans) groups. The first five modes of shape variation for the SSM corresponding to each bone were statistically compared between control and OCD groups using an analysis of variance (ANOVA) corrected with the Bonferroni for multiple comparisons. The first five modes of variation in the SSMs respectively represented 49% and 40% of the total variance of talus and tibia. Less than 5% of the variance per mode was described by the higher modes. Mode 5 of the talus (P = 0.004) primarily describing changes in the vertical neck angle and Mode 1 of the tibia (P < 0.0001) representing variations at the medial malleolus, showed statistically significant difference between the control and OCD groups. Shape differences exist between control and OCD groups. This indicates that a geometry modulated biomechanical behavior of the talocrural joint may be a risk factor for OCD. Copyright © 2016. Published by Elsevier Ltd.

Variation in practice and resource utilization associated with the diagnosis and management of appendicitis at freestanding children's hospitals: implications for value-based comparative analysis.

PubMed

Rice-Townsend, Samuel; Barnes, Jeff N; Hall, Matthew; Baxter, Jessica L; Rangel, Shawn J

2014-06-01

To characterize the scope and magnitude of practice variation associated with the diagnosis and treatment of appendicitis at freestanding children's hospitals. Variation in care has been associated with poor outcomes and is believed to be a key driver of excess health care spending. Retrospective cohort study of 13,328 patients treated with appendicitis at 34 children's hospitals (9/2010-9/2011). Patients were divided into complicated and uncomplicated cohorts and examined for interhospital variation in the use of diagnostic imaging (computed tomography or ultrasonography), laboratory tests, parenteral nutrition (PN), peripherally inserted central catheters (PICC), and hospital cost. The number and distribution of statistical outliers were calculated for all measures. Significant variation was found for all measures, including a 3.5-fold difference in preoperative imaging (aggregate rate: 49.0%, range across hospitals: 21.2%-73.5%, P < 0.001) and a 5-fold difference in preoperative laboratory utilization (aggregate median: 2 tests/encounter, range: 1-5 tests/encounter, P < 0.001). For patients with complicated appendicitis, we characterized a 12-fold difference in postoperative imaging (aggregate rate: 19.4%, range: 4.9%-61.6%, P < 0.001), a 48-fold difference in PICC lines (aggregate rate: 18.9%, range: 1.7%-81.8%, P < 0.001), and a 100-fold difference in PN utilization (aggregate rate: 9.3%, range: 0.4%-42.0%, P < 0.001). Median hospital cost differed 4-fold for patients with uncomplicated disease (aggregate median: $6804, range: $4200-$16,796, P < 0.001) and 4.6-fold for patients with complicated disease (aggregate median: $13,138, range: $5419-$24,779, P < 0.001). Statistical outliers on the basis of high and low utilization were identified for all measures. Significant variation exists in practice, resource utilization, and treatment-related cost associated with the management of appendicitis at freestanding children's hospitals. Value-based measures are needed for benchmarking and to prioritize collaborative quality improvement efforts.

Geographic variations in cervical cancer risk in San Luis Potosí state, Mexico: A spatial statistical approach.

PubMed

Terán-Hernández, Mónica; Ramis-Prieto, Rebeca; Calderón-Hernández, Jaqueline; Garrocho-Rangel, Carlos Félix; Campos-Alanís, Juan; Ávalos-Lozano, José Antonio; Aguilar-Robledo, Miguel

2016-09-29

Worldwide, Cervical Cancer (CC) is the fourth most common type of cancer and cause of death in women. It is a significant public health problem, especially in low and middle-income/Gross Domestic Product (GDP) countries. In the past decade, several studies of CC have been published, that identify the main modifiable and non-modifiable CC risk factors for Mexican women. However, there are no studies that attempt to explain the residual spatial variation in CC incidence In Mexico, i.e. spatial variation that cannot be ascribed to known, spatially varying risk factors. This paper uses a spatial statistical methodology that takes into account spatial variation in socio-economic factors and accessibility to health services, whilst allowing for residual, unexplained spatial variation in risk. To describe residual spatial variations in CC risk, we used generalised linear mixed models (GLMM) with both spatially structured and unstructured random effects, using a Bayesian approach to inference. The highest risk is concentrated in the southeast, where the Matlapa and Aquismón municipalities register excessive risk, with posterior probabilities greater than 0.8. The lack of coverage of Cervical Cancer-Screening Programme (CCSP) (RR 1.17, 95 % CI 1.12-1.22), Marginalisation Index (RR 1.05, 95 % CI 1.03-1.08), and lack of accessibility to health services (RR 1.01, 95 % CI 1.00-1.03) were significant covariates. There are substantial differences between municipalities, with high-risk areas mainly in low-resource areas lacking accessibility to health services for CC. Our results clearly indicate the presence of spatial patterns, and the relevance of the spatial analysis for public health intervention. Ignoring the spatial variability means to continue a public policy that does not tackle deficiencies in its national CCSP and to keep disadvantaging and disempowering Mexican women in regard to their health care.

Methods and statistics for combining motif match scores.

PubMed

Bailey, T L; Gribskov, M

1998-01-01

Position-specific scoring matrices are useful for representing and searching for protein sequence motifs. A sequence family can often be described by a group of one or more motifs, and an effective search must combine the scores for matching a sequence to each of the motifs in the group. We describe three methods for combining match scores and estimating the statistical significance of the combined scores and evaluate the search quality (classification accuracy) and the accuracy of the estimate of statistical significance of each. The three methods are: 1) sum of scores, 2) sum of reduced variates, 3) product of score p-values. We show that method 3) is superior to the other two methods in both regards, and that combining motif scores indeed gives better search accuracy. The MAST sequence homology search algorithm utilizing the product of p-values scoring method is available for interactive use and downloading at URL http:/(/)www.sdsc.edu/MEME.

Estimation of fine-scale recombination intensity variation in the white-echinus interval of D. melanogaster

PubMed Central

Singh, Nadia D.; Aquadro, Charles F.; Clark, Andrew G.

2009-01-01

Accurate assessment of local recombination rate variation is crucial for understanding the recombination process and for determining the impact of natural selection on linked sites. In Drosophila, local recombination intensity has been estimated primarily by statistical approaches, estimating the local slope of the relationship between the physical and genetic maps. However, these estimates are limited in resolution, and as a result, the physical scale at which recombination intensity varies in Drosophila is largely unknown. While there is some evidence suggesting as much as a 40-fold variation in crossover rate at a local scale in D. pseudoobscura, little is known about the fine-scale structure of recombination rate variation in D. melanogaster. Here, we experimentally examine the fine-scale distribution of crossover events in a 1.2 Mb region on the D. melanogaster X chromosome using a classic genetic mapping approach. Our results show that crossover frequency is significantly heterogeneous within this region, varying ~ 3.5 fold. Simulations suggest that this degree of heterogeneity is sufficient to affect levels of standing nucleotide diversity, although the magnitude of this effect is small. We recover no statistical association between empirical estimates of nucleotide diversity and recombination intensity, which is likely due to the limited number of loci sampled in our population genetic dataset. However, codon bias is significantly negatively correlated with fine-scale recombination intensity estimates, as expected. Our results shed light on the relevant physical scale to consider in evolutionary analyses relating to recombination rate, and highlight the motivations to increase the resolution of the recombination map in Drosophila. PMID:19504037

The role of spring and autumn phenological switches on spatiotemporal variation in temperate and boreal forest C balance: A FLUXNET synthesis

NASA Astrophysics Data System (ADS)

Richardson, A. D.; Reichstein, M.; Piao, S.; Ciais, P.; Luyssaert, S.; Stockli, R.; Friedl, M.; Gobron, N.; Fluxnet Site Pis, 21

2009-04-01

In temperate and boreal ecosystems, phenological transitions (particularly the timing of spring onset and autumn senescence) are thought to represent a major control on spatial and temporal variation in forest carbon sequestration. To investigate these patterns, we analyzed 153 site-years of data from the FLUXNET ‘La Thuile' database. Eddy covariance measurements of surface-atmosphere exchanges of carbon and water from 21 research sites at latitudes from 36°N to 67°N were used in the synthesis. We defined a range of phenological indicators based on the first (spring) and last (autumn) dates of (1) C source/sink transitions (‘carbon uptake period'); (2) measurable photosynthetic uptake (‘physiologically active period'); (3) relative thresholds for latent heat (evapotranspiration) flux; (4) phenological thresholds derived from a range of remote sensing products (JRC fAPAR, MOD12Q2, and the PROGNOSTIC model with MODIS data assimilation); and (5) a climatological metric based on the date where soil temperature equals mean annual air temperature. We then tested whether site-level flux anomalies were significantly correlated with phenological anomalies across these metrics, and whether the slopes of these relationships (representing the sensitivity to phenological variation) differed between deciduous broadleaf (DBF) and evergreen needleleaf (ENF) forests. Within sites, interannual variation in most phenological metrics was about 5-10 d, compared to 10-30 d across sites. Both spatial and temporal phenological variation were consistently larger at ENF, compared to DBF, sites. Averaged across metrics, phenological variability was roughly comparable in spring and autumn, both across (17 d) and within (9 d) sites. However, patterns of interannual variation in fluxes were less well explained by the derived phenological metrics than were patterns of spatial variation in fluxes. Also, the observed pattern strongly depended on the metric used, with flux-derived metrics generally explaining more, and remote sensing-derived metrics generally explaining less, of the variation in flux anomalies. We found that GPP (gross primary productivity) was consistently more sensitive (both in terms of magnitude and statistical significance; ≈3 g C m-2 d-1 for DBF and ≈2 g C m-2 d-1 for ENF) to phenology than was Reco (ecosystem respiration), which meant that NEP (net ecosystem productivity) tended to be increased both by earlier springs and later autumns. Without exception, when the difference between DBF and ENF in the sensitivity to phenological anomalies was statistically significant, DBF sensitivity was always larger in absolute magnitude than ENF sensitivity. Phenology explained a much larger fraction of the variation in fluxes across sites compared to within sites. Across sites, the rate of increase in GPP with an "exta" day in spring (≈10 g C m-2 d-1) was much larger than in autumn (≈3 g C m-2 d-1). Furthermore, a one-day increase in growing season length across sites increased annual NEP by just ≈2 g C m-2 d-1; this resulted from an increase in GPP of ≈6 g C m-2 d-1 being offset by an increase in RE of ≈4 g C m-2 d-1. In general, there was no statistically significant difference between DBF and ENF in the sensitivity to spatial variation in phenology for either NEP or the component fluxes GPP and Reco. In relation to both within- and across-site variation in phenology and fluxes, the results obtained tended to depend on the phenological metric used, i.e. definition of "start" and "end" of growing season, emphasizing the need for improved understanding of the relationships between these different metrics and ecosystem processes. Furthermore, the differences in flux-phenology relationships in the context of spatial and temporal variation in phenology raise questions about using results from either short-term or space-for-time studies to anticipate responses to future climate change.

GEOGRAPIC INFORMATION SYSTEMS IN DETERMINING ROAD TRAFFIC CRASH ANALYSIS IN IBADAN, NIGERIA.

PubMed

Rukewe, A; Taiwo, O J; Fatiregun, A A; Afuwape, O O; Alonge, T O

2014-01-01

Road traffic accidents are frequent in this environment, hence the need to determine the place of geographic information systems in the documentation of road traffic accidents. To investigate and document the variations in crash frequencies by types and across different road types in Ibadan, Nigeria. Road traffic accident data between January and June 2011 were obtained from the University College Hospital Emergency Department's trauma registry. All the traffic accidents were categorized into motor vehicular, motorbike and pedestrian crashes. Georeferencing of accident locations mentioned by patients was done using a combination of Google Earth and ArcGIS software. Nearest neighbor statistic, Moran's-I, Getis-Ord statistics, Student T-test, and ANOVA were used in investigating the spatial dynamics in crashes. Out of 600 locations recorded, 492 (82.0%) locations were correctly georeferenced. Crashes were clustered in space with motorbike crashes showing greatest clustering. There was significant difference in crashes between dual and non-dual carriage roads (P = 0.0001), but none between the inner city and the periphery (p = 0.115). However, significant variations also exist among the three categories analyzed (p = 0.004) and across the eleven Local Government Areas (P = 0.017). This study showed that the use of Geographic Information System can help in understanding variations in road traffic accident occurrence, while at the same time identifying locations and neighborhoods with unusually higher accidents frequency.

[Acute responses on lipid profile by practicing cycling].

PubMed

Díaz-Ríos, Lillian Karina; Rivera-Cisneros, Antonio Eugenio; Macías-Cervantes, Maciste Habacuc; Sánchez-González, Jorge Manuel; Guerrero-Martínez, Francisco Javier

2008-01-01

it has been demonstrated an association between the increase in physical activity and improvements in the lipid profile. to evaluate changes in the serum lipids caused by spinning practice. nine men and twelve women were studied, they underwent to an initial evaluation that included a treadmill effort test, in order to establish the physical fitness level. With the purpose of determine the lipids change, a blood sample was obtained before and after a typical spinning session. The design was prospective, experimental, longitudinal and comparative study. Student's t-test and regression model were used to determine the changes in the lipids concentrations, and its relation with the physical fitness level. A p value < or = 0.05 was required for statistical significance. lipids increase concentrations were observed (p < 0.05), except at triglycerides in men, in which it had a decrease. It was statistically significant relation between the physical fitness level and the percentage of high-density lipoproteins variation (r = 0.44, p = 0.046). the percentage of high-density lipoproteins variation was greater when the values of VO(2)max were higher. At greater level of medical fitness greater positive answer in this lipoproteins. In the case of the rest serum lipids, it was not observed relation between the level of medical fitness and the percentage of variation due to the execution of the spinning session.

Vitamin E and the risk of pneumonia: using the I 2 statistic to quantify heterogeneity within a controlled trial.

PubMed

Hemilä, Harri

2016-11-01

Analyses in nutritional epidemiology usually assume a uniform effect of a nutrient. Previously, four subgroups of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of Finnish male smokers aged 50-69 years were identified in which vitamin E supplementation either significantly increased or decreased the risk of pneumonia. The purpose of this present study was to quantify the level of true heterogeneity in the effect of vitamin E on pneumonia incidence using the I 2 statistic. The I 2 value estimates the percentage of total variation across studies that is explained by true differences in the treatment effect rather than by chance, with a range from 0 to 100 %. The I 2 statistic for the effect of vitamin E supplementation on pneumonia risk for five subgroups of the ATBC population was 89 % (95 % CI 78, 95 %), indicating that essentially all heterogeneity was true variation in vitamin E effect instead of chance variation. The I 2 statistic for heterogeneity in vitamin E effects on pneumonia risk was 92 % (95 % CI 80, 97 %) for three other ATBC subgroups defined by smoking level and leisure-time exercise level. Vitamin E decreased pneumonia risk by 69 % among participants who had the least exposure to smoking and exercised during leisure time (7·6 % of the ATBC participants), and vitamin E increased pneumonia risk by 68 % among those who had the highest exposure to smoking and did not exercise (22 % of the ATBC participants). These findings refute there being a uniform effect of vitamin E supplementation on the risk of pneumonia.

Simulation, identification and statistical variation in cardiovascular analysis (SISCA) - A software framework for multi-compartment lumped modeling.

PubMed

Huttary, Rudolf; Goubergrits, Leonid; Schütte, Christof; Bernhard, Stefan

2017-08-01

It has not yet been possible to obtain modeling approaches suitable for covering a wide range of real world scenarios in cardiovascular physiology because many of the system parameters are uncertain or even unknown. Natural variability and statistical variation of cardiovascular system parameters in healthy and diseased conditions are characteristic features for understanding cardiovascular diseases in more detail. This paper presents SISCA, a novel software framework for cardiovascular system modeling and its MATLAB implementation. The framework defines a multi-model statistical ensemble approach for dimension reduced, multi-compartment models and focuses on statistical variation, system identification and patient-specific simulation based on clinical data. We also discuss a data-driven modeling scenario as a use case example. The regarded dataset originated from routine clinical examinations and comprised typical pre and post surgery clinical data from a patient diagnosed with coarctation of aorta. We conducted patient and disease specific pre/post surgery modeling by adapting a validated nominal multi-compartment model with respect to structure and parametrization using metadata and MRI geometry. In both models, the simulation reproduced measured pressures and flows fairly well with respect to stenosis and stent treatment and by pre-treatment cross stenosis phase shift of the pulse wave. However, with post-treatment data showing unrealistic phase shifts and other more obvious inconsistencies within the dataset, the methods and results we present suggest that conditioning and uncertainty management of routine clinical data sets needs significantly more attention to obtain reasonable results in patient-specific cardiovascular modeling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantifying Variation in Gait Features from Wearable Inertial Sensors Using Mixed Effects Models

PubMed Central

Cresswell, Kellen Garrison; Shin, Yongyun; Chen, Shanshan

2017-01-01

The emerging technology of wearable inertial sensors has shown its advantages in collecting continuous longitudinal gait data outside laboratories. This freedom also presents challenges in collecting high-fidelity gait data. In the free-living environment, without constant supervision from researchers, sensor-based gait features are susceptible to variation from confounding factors such as gait speed and mounting uncertainty, which are challenging to control or estimate. This paper is one of the first attempts in the field to tackle such challenges using statistical modeling. By accepting the uncertainties and variation associated with wearable sensor-based gait data, we shift our efforts from detecting and correcting those variations to modeling them statistically. From gait data collected on one healthy, non-elderly subject during 48 full-factorial trials, we identified four major sources of variation, and quantified their impact on one gait outcome—range per cycle—using a random effects model and a fixed effects model. The methodology developed in this paper lays the groundwork for a statistical framework to account for sources of variation in wearable gait data, thus facilitating informative statistical inference for free-living gait analysis. PMID:28245602

A Reanalysis of Curvature in the Dose Response for Cancer and Modifications by Age at Exposure Following Radiation Therapy for Benign Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Little, Mark P., E-mail: mark.little@nih.gov; Stovall, Marilyn; Smith, Susan A.

Purpose: To assess the shape of the dose response for various cancer endpoints and modifiers by age and time. Methods and Materials: Reanalysis of the US peptic ulcer data testing for heterogeneity of radiogenic risk by cancer endpoint (stomach, pancreas, lung, leukemia, all other). Results: There are statistically significant (P<.05) excess risks for all cancer and for lung cancer and borderline statistically significant risks for stomach cancer (P=.07), and leukemia (P=.06), with excess relative risks Gy{sup -1} of 0.024 (95% confidence interval [CI] 0.011, 0.039), 0.559 (95% CI 0.221, 1.021), 0.042 (95% CI -0.002, 0.119), and 1.087 (95% CI -0.018,more » 4.925), respectively. There is statistically significant (P=.007) excess risk of pancreatic cancer when adjusted for dose-response curvature. General downward curvature is apparent in the dose response, statistically significant (P<.05) for all cancers, pancreatic cancer, and all other cancers (ie, other than stomach, pancreas, lung, leukemia). There are indications of reduction in relative risk with increasing age at exposure (for all cancers, pancreatic cancer), but no evidence for quadratic variations in relative risk with age at exposure. If a linear-exponential dose response is used, there is no significant heterogeneity in the dose response among the 5 endpoints considered or in the speed of variation of relative risk with age at exposure. The risks are generally consistent with those observed in the Japanese atomic bomb survivors and in groups of nuclear workers. Conclusions: There are excess risks for various malignancies in this data set. Generally there is a marked downward curvature in the dose response and significant reduction in relative risk with increasing age at exposure. The consistency of risks with those observed in the Japanese atomic bomb survivors and in groups of nuclear workers implies that there may be little sparing effect of fractionation of dose or low-dose-rate exposure.« less

Joint Clustering and Component Analysis of Correspondenceless Point Sets: Application to Cardiac Statistical Modeling.

PubMed

Gooya, Ali; Lekadir, Karim; Alba, Xenia; Swift, Andrew J; Wild, Jim M; Frangi, Alejandro F

2015-01-01

Construction of Statistical Shape Models (SSMs) from arbitrary point sets is a challenging problem due to significant shape variation and lack of explicit point correspondence across the training data set. In medical imaging, point sets can generally represent different shape classes that span healthy and pathological exemplars. In such cases, the constructed SSM may not generalize well, largely because the probability density function (pdf) of the point sets deviates from the underlying assumption of Gaussian statistics. To this end, we propose a generative model for unsupervised learning of the pdf of point sets as a mixture of distinctive classes. A Variational Bayesian (VB) method is proposed for making joint inferences on the labels of point sets, and the principal modes of variations in each cluster. The method provides a flexible framework to handle point sets with no explicit point-to-point correspondences. We also show that by maximizing the marginalized likelihood of the model, the optimal number of clusters of point sets can be determined. We illustrate this work in the context of understanding the anatomical phenotype of the left and right ventricles in heart. To this end, we use a database containing hearts of healthy subjects, patients with Pulmonary Hypertension (PH), and patients with Hypertrophic Cardiomyopathy (HCM). We demonstrate that our method can outperform traditional PCA in both generalization and specificity measures.

Scene-based nonuniformity correction using local constant statistics.

PubMed

Zhang, Chao; Zhao, Wenyi

2008-06-01

In scene-based nonuniformity correction, the statistical approach assumes all possible values of the true-scene pixel are seen at each pixel location. This global-constant-statistics assumption does not distinguish fixed pattern noise from spatial variations in the average image. This often causes the "ghosting" artifacts in the corrected images since the existing spatial variations are treated as noises. We introduce a new statistical method to reduce the ghosting artifacts. Our method proposes a local-constant statistics that assumes that the temporal signal distribution is not constant at each pixel but is locally true. This considers statistically a constant distribution in a local region around each pixel but uneven distribution in a larger scale. Under the assumption that the fixed pattern noise concentrates in a higher spatial-frequency domain than the distribution variation, we apply a wavelet method to the gain and offset image of the noise and separate out the pattern noise from the spatial variations in the temporal distribution of the scene. We compare the results to the global-constant-statistics method using a clean sequence with large artificial pattern noises. We also apply the method to a challenging CCD video sequence and a LWIR sequence to show how effective it is in reducing noise and the ghosting artifacts.

Reference Values for Shear Wave Elastography of Neck and Shoulder Muscles in Healthy Individuals.

PubMed

Ewertsen, Caroline; Carlsen, Jonathan; Perveez, Mohammed Aftab; Schytz, Henrik

2018-01-01

to establish reference values for ultrasound shear-wave elastography for pericranial muscles in healthy individuals (m. trapezius, m. splenius capitis, m. semispinalis capitis, m. sternocleidomastoideus and m. masseter). Also to evaluate day-to-day variations in the shear-wave speeds and evaluate the effect of the pennation of the muscle fibers, ie scanning parallel or perpendicularly to the fibers. 10 healthy individuals (5 males and 5 females) had their pericranial muscles examined with shear-wave elastography in two orthogonal planes on two different days for their dominant and non-dominant side. Mean shear wave speeds from 5 ROI's in each muscle, for each scan plane for the dominant and non-dominant side for the two days were calculated. The effect of the different parameters - muscle pennation, gender, dominant vs non-dominant side and day was evaluated. The effect of scan plane in relation to muscle pennation was statistically significant (p<0.0001). The mean shear-wave speed when scanning parallel to the muscle fibers was significantly higher than the mean shear-wave speed when scanning perpendicularly to the fibers. The day-to-day variation was statistically significant (p=0.0258), but not clinically relevant. Shear-wave speeds differed significantly between muscles. Mean shear wave speeds (m/s) for the muscles in the parallel plane were: for masseter 2.45 (SD:+/-0.25), semispinal 3.36 (SD:+/-0.75), splenius 3.04 (SD:+/-0.65), sternocleidomastoid 2.75 (SD:+/-0.23), trapezius 3.20 (SD:+/-0.27) and trapezius lateral 3.87 (SD:+/-3.87). The shear wave speed variation depended on the direction of scanning. Shear wave elastography may be a method to evaluate muscle stiffness in patients suffering from chronic neck pain.

Complication Rates of Ostomy Surgery Are High and Vary Significantly Between Hospitals

PubMed Central

Sheetz, Kyle H.; Waits, Seth A.; Krell, Robert W.; Morris, Arden M.; Englesbe, Michael J.; Mullard, Andrew; Campbell, Darrell A.; Hendren, Samantha

2014-01-01

Structured Abstract Background Ostomy surgery is common and has traditionally been associated with high rates of morbidity and mortality, suggesting an important target for quality improvement. Objective To evaluate the variation in outcomes after ostomy creation surgery within Michigan in order to identify targets for quality improvement. Design Retrospective cohort study. Setting The 34-hospital Michigan Surgical Quality Collaborative (MSQC). Patients Patients undergoing ostomy creation surgery between 2006-2011. Main outcome measures We evaluated hospitals' morbidity and mortality rates after risk-adjustment (age, comorbidities, emergency v. elective, procedure type). Results 4,250 patients underwent ostomy creation surgery; 3,866 (91.0%) procedures were open and 384 (9.0%) were laparoscopic. Unadjusted morbidity and mortality rates were 43.9% and 10.7%, respectively. Unadjusted morbidity rates for specific procedures ranged from 32.7% for ostomy-creation-only procedures to 47.8% for Hartmann's procedures. Risk-adjusted morbidity rates varied significantly between hospitals, ranging from 31.2% (95%CI 18.4-43.9) to 60.8% (95%CI 48.9-72.6). There were five statistically-significant high-outlier hospitals and three statistically-significant low-outlier hospitals for risk-adjusted morbidity. The pattern of complication types was similar between high- and low-outlier hospitals. Case volume, operative duration, and use of laparoscopic surgery did not explain the variation in morbidity rates across hospitals. Conclusions Morbidity and mortality rates for modern ostomy surgery are high. While this type of surgery has received little attention in healthcare policy, these data reveal that it is both common and uncommonly morbid. Variation in hospital performance provides an opportunity to identify quality improvement practices that could be disseminated among hospitals. PMID:24819104

SNW 2000 Proceedings. Oxide Thickness Variation Induced Threshold Voltage Fluctuations in Decanano MOSFETs: a 3D Density Gradient Simulation Study

NASA Technical Reports Server (NTRS)

Asenov, Asen; Kaya, S.; Davies, J. H.; Saini, S.

2000-01-01

We use the density gradient (DG) simulation approach to study, in 3D, the effect of local oxide thickness fluctuations on the threshold voltage of decanano MOSFETs in a statistical manner. A description of the reconstruction procedure for the random 2D surfaces representing the 'atomistic' Si-SiO2 interface variations is presented. The procedure is based on power spectrum synthesis in the Fourier domain and can include either Gaussian or exponential spectra. The simulations show that threshold voltage variations induced by oxide thickness fluctuation become significant when the gate length of the devices become comparable to the correlation length of the fluctuations. The extent of quantum corrections in the simulations with respect to the classical case and the dependence of threshold variations on the oxide thickness are examined.

Multiscale spatial and small-scale temporal variation in the composition of Riverine fish communities.

PubMed

Growns, Ivor; Astles, Karen; Gehrke, Peter

2006-03-01

We studied the multiscale (sites, river reaches and rivers) and short-term temporal (monthly) variability in a freshwater fish assemblage. We found that small-scale spatial variation and short-term temporal variability significantly influenced fish community structure in the Macquarie and Namoi Rivers. However, larger scale spatial differences between rivers were the largest source of variation in the data. The interaction between temporal change and spatial variation in fish community structure, whilst statistically significant, was smaller than the variation between rivers. This suggests that although the fish communities within each river changed between sampling occasions, the underlying differences between rivers were maintained. In contrast, the strongest interaction between temporal and spatial effects occurred at the smallest spatial scale, at the level of individual sites. This means whilst the composition of the fish assemblage at a given site may fluctuate, the magnitude of these changes is unlikely to affect larger scale differences between reaches within rivers or between rivers. These results suggest that sampling at any time within a single season will be sufficient to show spatial differences that occur over large spatial scales, such as comparisons between rivers or between biogeographical regions.

Prevalence and variations of the median maxillary labial frenum in children, adolescents, and adults in a diverse population.

PubMed

Townsend, Janice A; Brannon, Robert B; Cheramie, Toby; Hagan, Joseph

2013-01-01

The median maxillary labial frenum (MMLF) is a normal anatomic structure with inherent morphologic variations. This study sought to evaluate the prevalence of those variations in a diverse ethnic population and to educate practitioners about the prevalence of MMLF variations to prevent unnecessary biopsies. This study included adult, adolescent, and child patients at the Louisiana State University Health Science Center School of Dentistry. Among the 284 subjects examined, frenum normale was the most common frenum classification, followed by frenum with nodule and frenum with appendix. Most nodules were found in the intermediate third of the MMLF, while appendices were mainly found in the labial third. The prevalence of an appendix was significantly higher (P < 0.001) in Caucasians compared to African-Americans. The prevalence of nodules was marginally higher (P = 0.096) in Caucasians than in African-Americans. No other statistically significant differences were found with regard to ethnicity. Additionally, nodules and appendices on the MMLF were identified in all age groups, and may become more common with increasing age. The authors determined that variations of the MMLF are inherent and do not represent a pathologic condition, nor do they require biopsy for diagnostic purposes.

Using Statistical Process Control to Drive Improvement in Neonatal Care: A Practical Introduction to Control Charts.

PubMed

Gupta, Munish; Kaplan, Heather C

2017-09-01

Quality improvement (QI) is based on measuring performance over time, and variation in data measured over time must be understood to guide change and make optimal improvements. Common cause variation is natural variation owing to factors inherent to any process; special cause variation is unnatural variation owing to external factors. Statistical process control methods, and particularly control charts, are robust tools for understanding data over time and identifying common and special cause variation. This review provides a practical introduction to the use of control charts in health care QI, with a focus on neonatology. Copyright © 2017 Elsevier Inc. All rights reserved.

Variability of lotic macroinvertebrate assemblages and stream habitat characteristics across hierarchical landscape classifications.

PubMed

Mykrä, Heikki; Heino, Jani; Muotka, Timo

2004-09-01

Streams are naturally hierarchical systems, and their biota are affected by factors effective at regional to local scales. However, there have been only a few attempts to quantify variation in ecological attributes across multiple spatial scales. We examined the variation in several macroinvertebrate metrics and environmental variables at three hierarchical scales (ecoregions, drainage systems, streams) in boreal headwater streams. In nested analyses of variance, significant spatial variability was observed for most of the macroinvertebrate metrics and environmental variables examined. For most metrics, ecoregions explained more variation than did drainage systems. There was, however, much variation attributable to residuals, suggesting high among-stream variation in macroinvertebrate assemblage characteristics. Nonmetric multidimensional scaling (NMDS) and multiresponse permutation procedure (MRPP) showed that assemblage composition differed significantly among both drainage systems and ecoregions. The associated R-statistics were, however, very low, indicating wide variation among sites within the defined landscape classifications. Regional delineations explained most of the variation in stream water chemistry, ecoregions being clearly more influential than drainage systems. For physical habitat characteristics, by contrast, the among-stream component was the major source of variation. Distinct differences attributable to stream size were observed for several metrics, especially total number of taxa and abundance of algae-scraping invertebrates. Although ecoregions clearly account for a considerable amount of variation in macroinvertebrate assemblage characteristics, we suggest that a three-tiered classification system (stratification through ecoregion and habitat type, followed by assemblage prediction within these ecologically meaningful units) will be needed for effective bioassessment of boreal running waters.

Spatio-temporal patterns of Barmah Forest virus disease in Queensland, Australia.

PubMed

Naish, Suchithra; Hu, Wenbiao; Mengersen, Kerrie; Tong, Shilu

2011-01-01

Barmah Forest virus (BFV) disease is a common and wide-spread mosquito-borne disease in Australia. This study investigated the spatio-temporal patterns of BFV disease in Queensland, Australia using geographical information system (GIS) tools and geostatistical analysis. We calculated the incidence rates and standardised incidence rates of BFV disease. Moran's I statistic was used to assess the spatial autocorrelation of BFV incidences. Spatial dynamics of BFV disease was examined using semi-variogram analysis. Interpolation techniques were applied to visualise and display the spatial distribution of BFV disease in statistical local areas (SLAs) throughout Queensland. Mapping of BFV disease by SLAs reveals the presence of substantial spatio-temporal variation over time. Statistically significant differences in BFV incidence rates were identified among age groups (χ(2) = 7587, df = 7327,p<0.01). There was a significant positive spatial autocorrelation of BFV incidence for all four periods, with the Moran's I statistic ranging from 0.1506 to 0.2901 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the state. This is the first study to examine spatial and temporal variation in the incidence rates of BFV disease across Queensland using GIS and geostatistics. The BFV transmission varied with age and gender, which may be due to exposure rates or behavioural risk factors. There are differences in the spatio-temporal patterns of BFV disease which may be related to local socio-ecological and environmental factors. These research findings may have implications in the BFV disease control and prevention programs in Queensland.

Investigation of trends in flooding in the Tug Fork basin of Kentucky, Virginia, and West Virginia

USGS Publications Warehouse

Hirsch, Robert M.; Scott, Arthur G.; Wyant, Timothy

1982-01-01

Statistical analysis indicates that the average size of annual-flood peaks of the Tug Fork (Ky., Va., and W. Va.) has been increasing. However, additional statistical analysis does not indicate that the flood levels that were exceeded typically once or twice a year in the period 1947-79 are any more likely to be exceeded now than in 1947. Possible trends in streamchannel size also are investigated at three locations. No discernible trends in channel size are noted. Further statistical analysis of the trend in the size of annual-flood peaks shows that much of the annual variation is related to local rainfall and to the 'natural' hydrologic response in a relatively undisturbed subbasin. However, some statistical indication of trend persists after accounting for these natural factors, though it is of borderline statistical significance. Further study in the basin may relate flood magnitudes to both rainfall and to land use.

Variation among conventional cultivars could be used as a criterion for environmental safety assessment of Bt rice on nontarget arthropods

NASA Astrophysics Data System (ADS)

Wang, Fang; Dang, Cong; Chang, Xuefei; Tian, Junce; Lu, Zengbin; Chen, Yang; Ye, Gongyin

2017-02-01

The current difficulty facing risk evaluations of Bacillus thuringiensis (Bt) crops on nontarget arthropods (NTAs) is the lack of criteria for determining what represents unacceptable risk. In this study, we investigated the biological parameters in the laboratory and field population abundance of Nilaparvata lugens (Hemiptera: Delphacidae) on two Bt rice lines and the non-Bt parent, together with 14 other conventional rice cultivars. Significant difference were found in nymphal duration and fecundity of N. lugens fed on Bt rice KMD2, as well as field population density on 12 October, compared with non-Bt parent. However, compared with the variation among conventional rice cultivars, the variation of each parameter between Bt rice and the non-Bt parent was much smaller, which can be easily seen from low-high bar graphs and also the coefficient of variation value (C.V). The variation among conventional cultivars is proposed to be used as a criterion for the safety assessment of Bt rice on NTAs, particularly when statistically significant differences in several parameters are found between Bt rice and its non-Bt parent. Coefficient of variation is suggested as a promising parameter for ecological risk judgement of IRGM rice on NTAs.

Analysis of the sleep quality of elderly people using biomedical signals.

PubMed

Moreno-Alsasua, L; Garcia-Zapirain, B; Mendez-Zorrilla, A

2015-01-01

This paper presents a technical solution that analyses sleep signals captured by biomedical sensors to find possible disorders during rest. Specifically, the method evaluates electrooculogram (EOG) signals, skin conductance (GSR), air flow (AS), and body temperature. Next, a quantitative sleep quality analysis determines significant changes in the biological signals, and any similarities between them in a given time period. Filtering techniques such as the Fourier transform method and IIR filters process the signal and identify significant variations. Once these changes have been identified, all significant data is compared and a quantitative and statistical analysis is carried out to determine the level of a person's rest. To evaluate the correlation and significant differences, a statistical analysis has been calculated showing correlation between EOG and AS signals (p=0,005), EOG, and GSR signals (p=0,037) and, finally, the EOG and Body temperature (p=0,04). Doctors could use this information to monitor changes within a patient.

A Meta-Analytic Review of Gender Variations in Children's Language Use: Talkativeness, Affiliative Speech, and Assertive Speech

ERIC Educational Resources Information Center

Leaper, Campbell; Smith, Tara E.

2004-01-01

Three sets of meta-analyses examined gender effects on children's language use. Each set of analyses considered an aspect of speech that is considered to be gender typed: talkativeness, affiliative speech, and assertive speech. Statistically significant average effect sizes were obtained with all three language constructs. On average, girls were…

A Correlational Study of Principals' Leadership Style and Teacher Absenteeism

ERIC Educational Resources Information Center

Carter, Jason

2010-01-01

The purpose of this study was to determine whether McGregor's Theory X and Theory Y, gender, age, and years of experience of principals form a composite explaining the variation in teacher absences. It sought to determine whether all or any of these variables would be statistically significant in explaining the variance in absences for teachers.…

A standardised protocol for texture feature analysis of endoscopic images in gynaecological cancer.

PubMed

Neofytou, Marios S; Tanos, Vasilis; Pattichis, Marios S; Pattichis, Constantinos S; Kyriacou, Efthyvoulos C; Koutsouris, Dimitris D

2007-11-29

In the development of tissue classification methods, classifiers rely on significant differences between texture features extracted from normal and abnormal regions. Yet, significant differences can arise due to variations in the image acquisition method. For endoscopic imaging of the endometrium, we propose a standardized image acquisition protocol to eliminate significant statistical differences due to variations in: (i) the distance from the tissue (panoramic vs close up), (ii) difference in viewing angles and (iii) color correction. We investigate texture feature variability for a variety of targets encountered in clinical endoscopy. All images were captured at clinically optimum illumination and focus using 720 x 576 pixels and 24 bits color for: (i) a variety of testing targets from a color palette with a known color distribution, (ii) different viewing angles, (iv) two different distances from a calf endometrial and from a chicken cavity. Also, human images from the endometrium were captured and analysed. For texture feature analysis, three different sets were considered: (i) Statistical Features (SF), (ii) Spatial Gray Level Dependence Matrices (SGLDM), and (iii) Gray Level Difference Statistics (GLDS). All images were gamma corrected and the extracted texture feature values were compared against the texture feature values extracted from the uncorrected images. Statistical tests were applied to compare images from different viewing conditions so as to determine any significant differences. For the proposed acquisition procedure, results indicate that there is no significant difference in texture features between the panoramic and close up views and between angles. For a calibrated target image, gamma correction provided an acquired image that was a significantly better approximation to the original target image. In turn, this implies that the texture features extracted from the corrected images provided for better approximations to the original images. Within the proposed protocol, for human ROIs, we have found that there is a large number of texture features that showed significant differences between normal and abnormal endometrium. This study provides a standardized protocol for avoiding any significant texture feature differences that may arise due to variability in the acquisition procedure or the lack of color correction. After applying the protocol, we have found that significant differences in texture features will only be due to the fact that the features were extracted from different types of tissue (normal vs abnormal).

ON THE VARIATION OF SOLAR RADIUS IN ROTATION CYCLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Z. N.; Kong, D. F.; Xiang, N. B.

2015-01-10

The Date Compensated Discrete Fourier Transform and CLEANest algorithm are used to study the temporal variations of the solar radius observed at Rio de Janeiro Observatory from 1998 March 2 to 2009 November 6. The CLEANest spectra show several significant periodicities around 400, 312, 93.5, 86.2, 79.4, 70.9, 53.2, and 26.3 days. Then, combining the data on the daily solar radius measured at Calern Observatory and Rio de Janeiro Observatory and the corresponding daily sunspot areas, we study the short-term periodicity of the solar radius and the role of magnetic field in the variation of the solar radius. The rotation periodmore » of the daily solar radius is determined to be statistically significant. Moreover, its temporal evolution is anti-phase with that of sunspot activity, and it is found anti-phase with solar activity. Generally, the stronger solar activity is, the more obvious is the anti-phase relation of radius with solar activity. This indicates that strong magnetic fields have a greater inhibitive effect than weak magnetic fields on the variation of the radius.« less

Genetic variation in steelhead of Oregon and northern California

USGS Publications Warehouse

Reisenbichler, R.R.; McIntyre, J.D.; Solazzi, M.F.; Landino, S.W

1992-01-01

Steelhead Oncorhynchus mykiss from various sites between the Columbia River and the Mad River, California, were genetically characterized at 10 protein-coding loci or pairs of loci by starch gel electrophoresis. Fish from coastal streams differed from fish east of the Cascade Mountains and from fish of the Willamette River (a tributary of the Columbia River, west of the Cascade Mountains). Coastal steelhead from the northern part of the study area differed from those in the southern part. Genetic differentiation within and among drainages was not statistically significant; however, gene diversity analysis and the life history of steelhead suggested that fish from different drainages should be considered as separate populations. Genetic variation among fish in separate drainages was similar to that reported in northwestern Washington and less than that reported in British Columbia. Allele frequencies varied significantly among year-classes. Genetic variation within samples accounted for 98.3% of the total genetic variation observed in this study. Most hatchery populations differed from wild populations, suggesting that conservation of genetic diversity among and within wild populations could be facilitated by altering hatchery programs.

Spatial Variations in Vitreous Oxygen Consumption

PubMed Central

Murali, Karthik; Kang, Dongyang; Nazari, Hossein; Scianmarello, Nicholas; Cadenas, Enrique; Tai, Yu-Chong; Kashani, Amir; Humayun, Mark

2016-01-01

We investigated the spatial variation of vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior vitreous cavity and steady state vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-vitreous (N = 6) or the posterior vitreous (N = 6), we measured a statistically significant decrease in vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p<0.005 for mid-vitreous and p<0.018 for posterior vitreous at all distances). The mid-vitreous oxygen tension change was significantly different from the posterior vitreous oxygen tension change at 2 and 3mm distances from the respective oxygen source (p<0.001). We also found a statistically significant lower concentration of ascorbate in the mid-vitreous as compared to posterior vitreous (p = 0.02). We determined the reaction rate constant, k = 1.61 M-1s-1 ± 0.708 M-1s-1 (SE), of the oxidation of ascorbate which was modeled following a second order rate equation. Our data demonstrates that vitreous oxygen consumption is higher in the posterior vitreous compared to the mid-vitreous. We also show spatial variations in vitreous ascorbate concentration. PMID:26930281

Spatial Variations in Vitreous Oxygen Consumption.

PubMed

Murali, Karthik; Kang, Dongyang; Nazari, Hossein; Scianmarello, Nicholas; Cadenas, Enrique; Tai, Yu-Chong; Kashani, Amir; Humayun, Mark

2016-01-01

We investigated the spatial variation of vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior vitreous cavity and steady state vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-vitreous (N = 6) or the posterior vitreous (N = 6), we measured a statistically significant decrease in vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p<0.005 for mid-vitreous and p<0.018 for posterior vitreous at all distances). The mid-vitreous oxygen tension change was significantly different from the posterior vitreous oxygen tension change at 2 and 3mm distances from the respective oxygen source (p<0.001). We also found a statistically significant lower concentration of ascorbate in the mid-vitreous as compared to posterior vitreous (p = 0.02). We determined the reaction rate constant, k = 1.61 M(-1) s(-1) ± 0.708 M(-1) s(-1) (SE), of the oxidation of ascorbate which was modeled following a second order rate equation. Our data demonstrates that vitreous oxygen consumption is higher in the posterior vitreous compared to the mid-vitreous. We also show spatial variations in vitreous ascorbate concentration.

The role of ensemble-based statistics in variational assimilation of cloud-affected observations from infrared imagers

NASA Astrophysics Data System (ADS)

Hacker, Joshua; Vandenberghe, Francois; Jung, Byoung-Jo; Snyder, Chris

2017-04-01

Effective assimilation of cloud-affected radiance observations from space-borne imagers, with the aim of improving cloud analysis and forecasting, has proven to be difficult. Large observation biases, nonlinear observation operators, and non-Gaussian innovation statistics present many challenges. Ensemble-variational data assimilation (EnVar) systems offer the benefits of flow-dependent background error statistics from an ensemble, and the ability of variational minimization to handle nonlinearity. The specific benefits of ensemble statistics, relative to static background errors more commonly used in variational systems, have not been quantified for the problem of assimilating cloudy radiances. A simple experiment framework is constructed with a regional NWP model and operational variational data assimilation system, to provide the basis understanding the importance of ensemble statistics in cloudy radiance assimilation. Restricting the observations to those corresponding to clouds in the background forecast leads to innovations that are more Gaussian. The number of large innovations is reduced compared to the more general case of all observations, but not eliminated. The Huber norm is investigated to handle the fat tails of the distributions, and allow more observations to be assimilated without the need for strict background checks that eliminate them. Comparing assimilation using only ensemble background error statistics with assimilation using only static background error statistics elucidates the importance of the ensemble statistics. Although the cost functions in both experiments converge to similar values after sufficient outer-loop iterations, the resulting cloud water, ice, and snow content are greater in the ensemble-based analysis. The subsequent forecasts from the ensemble-based analysis also retain more condensed water species, indicating that the local environment is more supportive of clouds. In this presentation we provide details that explain the apparent benefit from using ensembles for cloudy radiance assimilation in an EnVar context.

Host-associated differences in morphometric traits of parasitic larvae Hirsutiella zachvatkini (Actinotrichida: Trombiculidae).

PubMed

Moniuszko, Hanna; Zaleśny, Grzegorz; Mąkol, Joanna

2015-09-01

Examination of host-associated variation in the chigger mite Hirsutiella zachvatkini (Schluger) revealed morphological differences among larvae infesting sympatric hosts: Apodemus agrarius, Apodemus flavicollis and Myodes glareolus. The analysis included 61 variables of larvae obtained from their gnathosoma, idiosoma and legs (measurements and counts). Statistically significant differences were observed for metric characters of the legs as opposed to the scutum. In view of the conspecificity of the mites, supported by comparison of COI gene products obtained from larvae and laboratory-reared deutonymphs, the observed variation is attributed to phenotypic plasticity. The knowledge of larval morphology, including intraspecific variation of metric characters, supported by molecular and host range data, places H. zachvatkini among the most comprehensively defined members of Trombiculidae.

Accounting for measurement error: a critical but often overlooked process.

PubMed

Harris, Edward F; Smith, Richard N

2009-12-01

Due to instrument imprecision and human inconsistencies, measurements are not free of error. Technical error of measurement (TEM) is the variability encountered between dimensions when the same specimens are measured at multiple sessions. A goal of a data collection regimen is to minimise TEM. The few studies that actually quantify TEM, regardless of discipline, report that it is substantial and can affect results and inferences. This paper reviews some statistical approaches for identifying and controlling TEM. Statistically, TEM is part of the residual ('unexplained') variance in a statistical test, so accounting for TEM, which requires repeated measurements, enhances the chances of finding a statistically significant difference if one exists. The aim of this paper was to review and discuss common statistical designs relating to types of error and statistical approaches to error accountability. This paper addresses issues of landmark location, validity, technical and systematic error, analysis of variance, scaled measures and correlation coefficients in order to guide the reader towards correct identification of true experimental differences. Researchers commonly infer characteristics about populations from comparatively restricted study samples. Most inferences are statistical and, aside from concerns about adequate accounting for known sources of variation with the research design, an important source of variability is measurement error. Variability in locating landmarks that define variables is obvious in odontometrics, cephalometrics and anthropometry, but the same concerns about measurement accuracy and precision extend to all disciplines. With increasing accessibility to computer-assisted methods of data collection, the ease of incorporating repeated measures into statistical designs has improved. Accounting for this technical source of variation increases the chance of finding biologically true differences when they exist.

A comparison of workload and morbidity recording by partners in a group practice

PubMed Central

Carney, T. A.

1980-01-01

A survey was carried out of one year's workload and morbidity recording by three partners in a semi-rural teaching practice. Despite an equal workload of patient contacts there were shown to be statistically significant differences between the partners in the number of return consultations, the sex and age of the patients seen, and in nine diagnostic groups. The statistically significant differences in the latter groups appear to have been caused by variations in policy for recalling patients and the different sex and age groups of the patients consulting the partners, not by diagnostic preferences. A lack of previous experience affected one group. The partners did not find the discussion of these differences to be threatening. PMID:7441620

Uncertainties in radon related to house-specific factors and proximity to geological boundaries in England.

PubMed

Hunter, Nezahat; Muirhead, Colin R; Miles, Jon C H; Appleton, J Donald

2009-08-01

Data collected as a part of a survey on radon concentrations from about 40 000 dwellings in England for six contrasting geological units were analysed to evaluate the impact of house-specific factors (building characteristics and construction dates) and of proximity to geological boundaries. After adjusting for temperature and outdoor radon, geological unit, house type, double glazing and date of building were found to have a statistically significant influence on indoor radon concentrations and explained about 29 % of the total variation between dwellings in logarithmically transformed radon values. In addition, there were statistically significant differences in radon concentrations according to proximity to geological boundaries categories for most of the geological units, but no consistent pattern could be detected.

Acetylsalicylic acid does not reduce the intraocular pressure variation in ocular hypertension or glaucoma.

PubMed

Lindén, C; Alm, A

2000-03-01

The purpose of this study was to measure if intraocular pressure (IOP) and IOP variations in patients with ocular hypertension and glaucoma are decreased by acetylsalicylic acid (ASA). The hypothesis to be tested was that short-term fluctuations in the IOP are caused by breaks of the inner wall of Schlemm's canal that are repaired by platelets inducing a cycle of breaks and repair. Furthermore, prostaglandins affect uveoscleral outflow and ASA inhibits prostaglandin biosynthesis and platelet aggregation. This implies that ASA may have complex effects on the IOP and its variations.In 28 patients with ocular hypertension or glaucoma the IOP was measured seven times during 2 hr on two succeeding days. Five hundred mg ASA or placebo was administrated orally in a masked fashion 15 hr prior to the second session. After wash-out, this procedure was repeated with a cross-over design. The same study outline was used in 28 glaucoma patients except for the cross-over design. There were no statistically significant differences in the mean IOP or in the IOP variations between the placebo treated and the ASA treated eyes in either group, and there were no significant differences between the day before and after treatment in any group. The results suggest that ASA does not affect IOP variations in a clinically significant way and that a single dose of ASA has no significant effect on mean IOP. Copyright 2000 Academic Press.

Processed dairy beverages pH evaluation: consequences of temperature variation.

PubMed

Ferreira, Fabiana Vargas; Pozzobon, Roselaine Terezinha

2009-01-01

This study assessed the pH from processed dairy beverages as well as eventual consequences deriving from different ingestion temperatures. 50 adults who accompanied children attended to at the Dentistry School were randomly selected and they answered a questionnaire on beverages. The beverages were divided into 4 groups: yogurt (GI) fermented milk (GII), chocolate-based products (GIII) and fermented dairy beverages (GIV). They were asked which type, flavor and temperature. The most popular beverages were selected, and these made up the sample. A pH meter Quimis 400A device was used to verify pH. The average pH from each beverage was calculated and submitted to statistical analysis (Variance and Tukey test with a 5% significance level). for groups I, II and III beverages, type x temperature interaction was significant, showing the pH averages were influenced by temperature variation. At iced temperatures, they presented lower pH values, which were considered statistically significant when compared to the values found for the same beverages at room temperature. All dairy beverages, with the exception of the chocolate-based type presented pH below critical level for enamel and present corrosive potential; as to ingestion temperature, iced temperature influenced pH reducing its values, in vitro.

When do children get burnt?

PubMed

Verey, Frances; Lyttle, Mark D; Lawson, Zoe; Greenwood, Rosemary; Young, Amber

2014-11-01

Burns are a cause of more than 5000 paediatric hospital admissions per year in England and Wales. Injury prevention and service provision may be better planned with knowledge of burn timing. Prospectively collected records from 1st January 2010 to 31st December 2011 were analysed. All episodes involving patients less than 16 years of age reviewed by the South West Children's Burns Centre were included. Data was collected from 1480 records to investigate seasonal, weekly, and daily variation. Day to day analysis showed significantly more burns occurred on Saturday and Sunday than Monday-Friday (p<0.001). Of all burns, 46% occurred within the time-period 08:00-15:59; however the mean hourly rate of burns was highest between 16:00 and 18:59. Of the larger burns (>10% body surface area), 38% occurred after 19:00. There was no statistically significant variation in the monthly (p=0.105) or seasonal (p=0.270) distribution of burns. Bank holidays did not cause a statistically significant increase in numbers. Injury prevention strategies are likely to have most volume impact by increasing awareness of the peak time for burns in children, enabling parents at home with young children to modify any risky behaviour and by targeting older children and their behaviour. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Copy number variation of human AMY1 is a minor contributor to variation in salivary amylase expression and activity.

PubMed

Carpenter, Danielle; Mitchell, Laura M; Armour, John A L

2017-02-20

Salivary amylase in humans is encoded by the copy variable gene AMY1 in the amylase gene cluster on chromosome 1. Although the role of salivary amylase is well established, the consequences of the copy number variation (CNV) at AMY1 on salivary amylase protein production are less well understood. The amylase gene cluster is highly structured with a fundamental difference between odd and even AMY1 copy number haplotypes. In this study, we aimed to explore, in samples from 119 unrelated individuals, not only the effects of AMY1 CNV on salivary amylase protein expression and amylase enzyme activity but also whether there is any evidence for underlying difference between the common haplotypes containing odd numbers of AMY1 and even copy number haplotypes. AMY1 copy number was significantly correlated with the variation observed in salivary amylase production (11.7% of variance, P < 0.0005) and enzyme activity (13.6% of variance, P < 0.0005) but did not explain the majority of observed variation between individuals. AMY1-odd and AMY1-even haplotypes showed a different relationship between copy number and expression levels, but the difference was not statistically significant (P = 0.052). Production of salivary amylase is correlated with AMY1 CNV, but the majority of interindividual variation comes from other sources. Long-range haplotype structure may affect expression, but this was not significant in our data.

On the implications of the classical ergodic theorems: analysis of developmental processes has to focus on intra-individual variation.

PubMed

Molenaar, Peter C M

2008-01-01

It is argued that general mathematical-statistical theorems imply that standard statistical analysis techniques of inter-individual variation are invalid to investigate developmental processes. Developmental processes have to be analyzed at the level of individual subjects, using time series data characterizing the patterns of intra-individual variation. It is shown that standard statistical techniques based on the analysis of inter-individual variation appear to be insensitive to the presence of arbitrary large degrees of inter-individual heterogeneity in the population. An important class of nonlinear epigenetic models of neural growth is described which can explain the occurrence of such heterogeneity in brain structures and behavior. Links with models of developmental instability are discussed. A simulation study based on a chaotic growth model illustrates the invalidity of standard analysis of inter-individual variation, whereas time series analysis of intra-individual variation is able to recover the true state of affairs. (c) 2007 Wiley Periodicals, Inc.

Digital immunohistochemistry platform for the staining variation monitoring based on integration of image and statistical analyses with laboratory information system.

PubMed

Laurinaviciene, Aida; Plancoulaine, Benoit; Baltrusaityte, Indra; Meskauskas, Raimundas; Besusparis, Justinas; Lesciute-Krilaviciene, Daiva; Raudeliunas, Darius; Iqbal, Yasir; Herlin, Paulette; Laurinavicius, Arvydas

2014-01-01

Digital immunohistochemistry (IHC) is one of the most promising applications brought by new generation image analysis (IA). While conventional IHC staining quality is monitored by semi-quantitative visual evaluation of tissue controls, IA may require more sensitive measurement. We designed an automated system to digitally monitor IHC multi-tissue controls, based on SQL-level integration of laboratory information system with image and statistical analysis tools. Consecutive sections of TMA containing 10 cores of breast cancer tissue were used as tissue controls in routine Ki67 IHC testing. Ventana slide label barcode ID was sent to the LIS to register the serial section sequence. The slides were stained and scanned (Aperio ScanScope XT), IA was performed by the Aperio/Leica Colocalization and Genie Classifier/Nuclear algorithms. SQL-based integration ensured automated statistical analysis of the IA data by the SAS Enterprise Guide project. Factor analysis and plot visualizations were performed to explore slide-to-slide variation of the Ki67 IHC staining results in the control tissue. Slide-to-slide intra-core IHC staining analysis revealed rather significant variation of the variables reflecting the sample size, while Brown and Blue Intensity were relatively stable. To further investigate this variation, the IA results from the 10 cores were aggregated to minimize tissue-related variance. Factor analysis revealed association between the variables reflecting the sample size detected by IA and Blue Intensity. Since the main feature to be extracted from the tissue controls was staining intensity, we further explored the variation of the intensity variables in the individual cores. MeanBrownBlue Intensity ((Brown+Blue)/2) and DiffBrownBlue Intensity (Brown-Blue) were introduced to better contrast the absolute intensity and the colour balance variation in each core; relevant factor scores were extracted. Finally, tissue-related factors of IHC staining variance were explored in the individual tissue cores. Our solution enabled to monitor staining of IHC multi-tissue controls by the means of IA, followed by automated statistical analysis, integrated into the laboratory workflow. We found that, even in consecutive serial tissue sections, tissue-related factors affected the IHC IA results; meanwhile, less intense blue counterstain was associated with less amount of tissue, detected by the IA tools.

Digital immunohistochemistry platform for the staining variation monitoring based on integration of image and statistical analyses with laboratory information system

PubMed Central

2014-01-01

Background Digital immunohistochemistry (IHC) is one of the most promising applications brought by new generation image analysis (IA). While conventional IHC staining quality is monitored by semi-quantitative visual evaluation of tissue controls, IA may require more sensitive measurement. We designed an automated system to digitally monitor IHC multi-tissue controls, based on SQL-level integration of laboratory information system with image and statistical analysis tools. Methods Consecutive sections of TMA containing 10 cores of breast cancer tissue were used as tissue controls in routine Ki67 IHC testing. Ventana slide label barcode ID was sent to the LIS to register the serial section sequence. The slides were stained and scanned (Aperio ScanScope XT), IA was performed by the Aperio/Leica Colocalization and Genie Classifier/Nuclear algorithms. SQL-based integration ensured automated statistical analysis of the IA data by the SAS Enterprise Guide project. Factor analysis and plot visualizations were performed to explore slide-to-slide variation of the Ki67 IHC staining results in the control tissue. Results Slide-to-slide intra-core IHC staining analysis revealed rather significant variation of the variables reflecting the sample size, while Brown and Blue Intensity were relatively stable. To further investigate this variation, the IA results from the 10 cores were aggregated to minimize tissue-related variance. Factor analysis revealed association between the variables reflecting the sample size detected by IA and Blue Intensity. Since the main feature to be extracted from the tissue controls was staining intensity, we further explored the variation of the intensity variables in the individual cores. MeanBrownBlue Intensity ((Brown+Blue)/2) and DiffBrownBlue Intensity (Brown-Blue) were introduced to better contrast the absolute intensity and the colour balance variation in each core; relevant factor scores were extracted. Finally, tissue-related factors of IHC staining variance were explored in the individual tissue cores. Conclusions Our solution enabled to monitor staining of IHC multi-tissue controls by the means of IA, followed by automated statistical analysis, integrated into the laboratory workflow. We found that, even in consecutive serial tissue sections, tissue-related factors affected the IHC IA results; meanwhile, less intense blue counterstain was associated with less amount of tissue, detected by the IA tools. PMID:25565007

The Extended Community-Level Effects of Genetic Variation in Foliar Wax Chemistry in the Forest Tree Eucalyptus globulus.

PubMed

Gosney, Benjamin; O'Reilly-Wapstra, Julianne; Forster, Lynne; Whiteley, Carmen; Potts, Brad

2017-05-01

Genetic variation in foundation trees can influence dependent communities, but little is known about the mechanisms driving these extended genetic effects. We studied the potential chemical drivers of genetic variation in the dependent foliar community of the focal tree Eucalyptus globulus. We focus on the role of cuticular waxes and compare the effects to that of the terpenes, a well-studied group of secondary compounds known to be bioactive in eucalypts. The canopy community was quantified based on the abundance of thirty-nine distinctive arthropod and fungal symptoms on foliar samples collected from canopies of 246 progeny from 13 E. globulus sub-races grown in a common garden trial. Cuticular waxes and foliar terpenes were quantified using gas chromatography - mass spectrometry (GC-MC). A total of 4 of the 13 quantified waxes and 7 of the 16 quantified terpenes were significantly associated with the dependent foliar community. Variation in waxes explained 22.9% of the community variation among sub-races, which was equivalent to that explained by terpenes. In combination, waxes and terpenes explained 35% of the genetic variation among sub-races. Only a small proportion of wax and terpene compounds showing statistically significant differences among sub-races were implicated in community level effects. The few significant waxes have previously shown evidence of divergent selection in E. globulus, which signals that adaptive variation in phenotypic traits may have extended effects. While highlighting the role of the understudied cuticular waxes, this study demonstrates the complexity of factors likely to lead to community genetic effects in foundation trees.

Association of ALOX15 gene polymorphisms with obesity-related phenotypes in Chinese nuclear families with male offspring.

PubMed

Ke, Yao-hua; Xiao, Wen-jin; He, Jin-wei; Zhang, Hao; Yu, Jin-bo; Hu, Wei-wei; Gu, Jie-mei; Gao, Gao; Yue, Hua; Wang, Chun; Hu, Yun-qiu; Li, Miao; Liu, Yu-juan; Fu, Wen-zhen; Zhang, Zhen-lin

2012-02-01

Genetic variation in ALOX12, which encoded human 12-lipoxygenase, was found to be associated with fat mass in young Chinese men. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) and haplotypes in the ALOX15 gene and obesity-related phenotypes in Chinese nuclear families with male offspring. We recruited 1,296 subjects from 427 nuclear families with male offspring and genotyped five SNPs (rs9894225, rs748694, rs2619112, rs2619118, and rs916055) in the ALOX15 gene locus. The total fat mass (TFM), trunk fat mass (tFM), leg fat mass (LFM) and arm fat mass (AFM) were measured using dual-energy X-ray absorptiometry (DXA). The percentage of fat mass (PFM) was the ratio of TFM and body weight. The association between SNPs and haplotypes of ALOX15 and obesity-related phenotypic variation was measured using quantitative transmission disequilibrium test (QTDT). Using QTDT to measure family-based genetic association, we found that rs916055 had a statistically significant association with PFM (P=0.038), whereas rs916055 had a marginal but statistically insignificant association with tFM (P=0.093). The multiple-parameter 1000 permutations test agreed with the family-based association results: both showed that rs916055 had a statistically significant association with PFM (P=0.033). rs916055 in ALOX15 gene was significantly associated with the percentage of fat mass in Chinese nuclear families with male offspring in the family-based association study using QTDT approach.

Simulated linear test applied to quantitative proteomics.

PubMed

Pham, T V; Jimenez, C R

2016-09-01

Omics studies aim to find significant changes due to biological or functional perturbation. However, gene and protein expression profiling experiments contain inherent technical variation. In discovery proteomics studies where the number of samples is typically small, technical variation plays an important role because it contributes considerably to the observed variation. Previous methods place both technical and biological variations in tightly integrated mathematical models that are difficult to adapt for different technological platforms. Our aim is to derive a statistical framework that allows the inclusion of a wide range of technical variability. We introduce a new method called the simulated linear test, or the s-test, that is easy to implement and easy to adapt for different models of technical variation. It generates virtual data points from the observed values according to a pre-defined technical distribution and subsequently employs linear modeling for significance analysis. We demonstrate the flexibility of the proposed approach by deriving a new significance test for quantitative discovery proteomics for which missing values have been a major issue for traditional methods such as the t-test. We evaluate the result on two label-free (phospho) proteomics datasets based on ion-intensity quantitation. Available at http://www.oncoproteomics.nl/software/stest.html : t.pham@vumc.nl. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Spectral Structure of Temperature Variations in the Midlatitude Mesopause Region

NASA Astrophysics Data System (ADS)

Perminov, V. I.; Semenov, A. I.; Medvedeva, I. V.; Pertsev, N. N.; Sukhodoev, V. A.

2018-01-01

Long-term series of midnight temperature in the mesopause region have been obtained from spectral observations of hydroxyl airglow emission (OH(6-2) λ840 nm band) at the Tory station (52° N, 103° E) in 2008-2016 and Zvenigorod (56° N, 37° E) station in 2000-2016. On their basis, the Lomb-Scargle spectra of the variations in the period range from 12 days to 11 years have been determined. Estimates of the amplitudes of statistically significant temperature fluctuations are made. The dominant oscillations are the first and second harmonics of the annual variation, the amplitudes of which are 23-24 K and 4-7 K, respectively. The remaining variations, the number of which was 16 for the Tory and 22 for Zvenigorod stations, have small amplitudes (0.5-3 K). Oscillations with combinational frequencies, which arise from modulation of the annual variation harmonics, are observed in a structure of the variation spectra in addition to interannual oscillations (periods from 2 to 11 years) and harmonics of the annual variation (up to its tenth harmonic).

Longitudinal Variations in the Variability of Spread F Occurrence

NASA Astrophysics Data System (ADS)

Groves, K. M.; Bridgwood, C.; Carrano, C. S.

2017-12-01

The complex dynamics of the equatorial ionosphere have attracted the interest and attention of researchers for many decades. The relatively local processes that give rise to large meridional gradients have been well documented and the associated terminology has entered the common lexicon of ionospheric research (e.g., fountain effect, equatorial anomaly, bubbles, Spread F). Zonal variations have also been noted, principally at the level of determining longitudinal differences in seasonal activity patterns. Due to a historical lack of high resolution ground-based observations at low latitudes, the primary source of data for such analyses has been space-based observations from satellites such as ROCSAT, DMSP, C/NOFS that measure in situ electron density variations. An important longitudinal variation in electron density structure associated with non-migrating diurnal tides was discovered by Immel et al. in 2006 using data from the FUV sensor aboard the NASA IMAGE satellite. These satellite observations have been very helpful in identifying the structural characteristics of the equatorial ionosphere and the occurrence of Spread F, but they provide little insight into variations in scintillation features and potential differences in bubble development characteristics. Moreover space-based studies tend towards the statistics of occurrence frequency over periods of weeks to months. A recent analysis of daily spread F occurrence as determined by low latitude VHF scintillation activity shows that statistical results that are consistent with previous space-based observations, but the level of variability in the occurrence data show marked variations with longitude. For example, the American sector shows very low in-season variability while the African and Asian sectors exhibit true day-to-day variability regardless of seasonal variations. The results have significant implications for space weather as they suggest that long-term forecasts of equatorial scintillation may be meaningful within specific longitude boundaries.

A BAYESIAN SPATIAL AND TEMPORAL MODELING APPROACH TO MAPPING GEOGRAPHIC VARIATION IN MORTALITY RATES FOR SUBNATIONAL AREAS WITH R-INLA.

PubMed

Khana, Diba; Rossen, Lauren M; Hedegaard, Holly; Warner, Margaret

2018-01-01

Hierarchical Bayes models have been used in disease mapping to examine small scale geographic variation. State level geographic variation for less common causes of mortality outcomes have been reported however county level variation is rarely examined. Due to concerns about statistical reliability and confidentiality, county-level mortality rates based on fewer than 20 deaths are suppressed based on Division of Vital Statistics, National Center for Health Statistics (NCHS) statistical reliability criteria, precluding an examination of spatio-temporal variation in less common causes of mortality outcomes such as suicide rates (SRs) at the county level using direct estimates. Existing Bayesian spatio-temporal modeling strategies can be applied via Integrated Nested Laplace Approximation (INLA) in R to a large number of rare causes of mortality outcomes to enable examination of spatio-temporal variations on smaller geographic scales such as counties. This method allows examination of spatiotemporal variation across the entire U.S., even where the data are sparse. We used mortality data from 2005-2015 to explore spatiotemporal variation in SRs, as one particular application of the Bayesian spatio-temporal modeling strategy in R-INLA to predict year and county-specific SRs. Specifically, hierarchical Bayesian spatio-temporal models were implemented with spatially structured and unstructured random effects, correlated time effects, time varying confounders and space-time interaction terms in the software R-INLA, borrowing strength across both counties and years to produce smoothed county level SRs. Model-based estimates of SRs were mapped to explore geographic variation.

Evolution of seismicity in relation to fluid injection in the North-Western part of The Geysers geothermal field

NASA Astrophysics Data System (ADS)

Leptokaropoulos, Konstantinos; Staszek, Monika; Lasocki, Stanisław; Martínez-Garzón, Patricia; Kwiatek, Grzegorz

2018-02-01

The Geysers geothermal field located in California, USA, is the largest geothermal site in the world, operating since the 1960s. We here investigate and quantify the correlation between temporal seismicity evolution and variation of the injection data by examination of time-series through specified statistical tools (binomial test to investigate significant rate changes, cross correlation between seismic and injection data, b-value variation analysis). To do so, we utilize seismicity and operational data associated with two injection wells (Prati-9 and Prati-29) which cover a time period of approximately 7 yr (from November 2007 to August 2014). The seismicity is found to be significantly positively correlated with the injection rate. The maximum correlation occurs with a seismic response delay of ˜2 weeks, following injection operations. Those results are very stable even after considering hypocentral uncertainties, by applying a vertical shift of the events foci up to 300 m. Our analysis indicates also time variations of b-value, which exhibits significant positive correlation with injection rates.

Modeling Soot Oxidation and Gasification with Bayesian Statistics

DOE PAGES

Josephson, Alexander J.; Gaffin, Neal D.; Smith, Sean T.; ...

2017-08-22

This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H 2O or CO 2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumptionmore » model with quantified uncertainty is presented here along with a discussion of associated implications. The oxidation results are found to be consistent with previous studies. Significant variation is found in the CO 2 gasification rates.« less

Modeling Soot Oxidation and Gasification with Bayesian Statistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Josephson, Alexander J.; Gaffin, Neal D.; Smith, Sean T.

This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H 2O or CO 2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumptionmore » model with quantified uncertainty is presented here along with a discussion of associated implications. The oxidation results are found to be consistent with previous studies. Significant variation is found in the CO 2 gasification rates.« less

Assessment of Eustachian tube function in patients with tympanic membrane retraction and in normal subjects.

PubMed

Canali, Inesângela; Petersen Schmidt Rosito, Letícia; Siliprandi, Bruno; Giugno, Cláudia; Selaimen da Costa, Sady

The diagnosis of Eustachian tube dysfunctions is essential for better understanding of the pathogenesis of chronic otitis media. A series of tests to assess tube function are described in the literature; however, they are methodologically heterogeneous, with differences ranging from application protocols to standardization of tests and their results. To evaluate the variation in middle ear pressure in patients with tympanic membrane retraction and in normal patients during tube function tests, as well as to evaluate intra-individual variation between these tests. An observational, contemporary, cross-sectional study was conducted, in which the factor under study was the variation in middle ear pressure during tube function tests (Valsalva maneuver, sniff test, Toynbee maneuver) in healthy patients and in patients with mild and moderate/severe tympanic retraction. A total of 38 patients (76 ears) were included in the study. Patients underwent tube function tests at two different time points to determine pressure measurements after each maneuver. Statistical analysis was performed using SPSS software, version 18.0, considering p-values <0.05 as statistically significant. Mean (standard deviation) age was 11 (2.72) years; 55.3% of patients were male and 44.7% female. The prevalence of type A tympanogram was higher among participants with healthy ears and those with mild retraction, whereas type C tympanograms were more frequent in the moderate/severe retraction group. An increase in middle ear pressure was observed during the Valsalva maneuver at the first time point evaluated in all three groups of ears (p=0.012). The variation in pressure was not significant either for the sniff test or for the Toynbee maneuver at the two time points evaluated (p≥0.05). Agreement between measurements obtained at the two different time points was weak to moderate for all tests in all three groups of ears, and the variations in discrepancy between measurements were higher in ears with moderate/severe tympanic retraction. In this study population, the mean pressure in the middle ear showed significant variation only during the Valsalva maneuver at the first time point evaluated in the three groups of ears. Normal ears and those with mild retraction behaved similarly in all tests. The tested maneuvers exhibited weak to moderate intra-individual variation, with the greatest variation occurring in ears with moderate/severe retraction. Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Effects of Long Term Thermal Exposure on Chemically Pure (CP) Titanium Grade 2 Room Temperature Tensile Properties and Microstructure

NASA Technical Reports Server (NTRS)

Ellis, David L.

2007-01-01

Room temperature tensile testing of Chemically Pure (CP) Titanium Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K for times up to 5,000 h. No significant changes in microstructure or failure mechanism were observed. A statistical analysis of the data was performed. Small statistical differences were found, but all properties were well above minimum values for CP Ti Grade 2 as defined by ASTM standards and likely would fall within normal variation of the material.

Environmental Variables Explain Genetic Structure in a Beetle-Associated Nematode

PubMed Central

McGaughran, Angela; Morgan, Katy; Sommer, Ralf J.

2014-01-01

The distribution of a species is a complex expression of its ecological and evolutionary history and integrating population genetic, environmental, and ecological data can provide new insights into the effects of the environment on the population structure of species. Previous work demonstrated strong patterns of genetic differentiation in natural populations of the hermaphroditic nematode Pristionchus pacificus in its La Réunion Island habitat, but gave no clear understanding of the role of the environment in structuring this variation. Here, we present what is to our knowledge the first study to statistically evaluate the role of the environment in shaping the structure and distribution of nematode populations. We test the hypothesis that genetic structure in P. pacificus is influenced by environmental variables, by combining population genetic analyses of microsatellite data from 18 populations and 370 strains, with multivariate statistics on environmental data, and species distribution modelling. We assess and quantify the relative importance of environmental factors (geographic distance, altitude, temperature, precipitation, and beetle host) on genetic variation among populations. Despite the fact that geographic populations of P. pacificus comprise vast genetic diversity sourced from multiple ancestral lineages, we find strong evidence for local associations between environment and genetic variation. Further, we show that significantly more genetic variation in P. pacificus populations is explained by environmental variation than by geographic distances. This supports a strong role for environmental heterogeneity vs. genetic drift in the divergence of populations, which we suggest may be influenced by adaptive forces. PMID:24498073

Body size and allometric variation in facial shape in children.

PubMed

Larson, Jacinda R; Manyama, Mange F; Cole, Joanne B; Gonzalez, Paula N; Percival, Christopher J; Liberton, Denise K; Ferrara, Tracey M; Riccardi, Sheri L; Kimwaga, Emmanuel A; Mathayo, Joshua; Spitzmacher, Jared A; Rolian, Campbell; Jamniczky, Heather A; Weinberg, Seth M; Roseman, Charles C; Klein, Ophir; Lukowiak, Ken; Spritz, Richard A; Hallgrimsson, Benedikt

2018-02-01

Morphological integration, or the tendency for covariation, is commonly seen in complex traits such as the human face. The effects of growth on shape, or allometry, represent a ubiquitous but poorly understood axis of integration. We address the question of to what extent age and measures of size converge on a single pattern of allometry for human facial shape. Our study is based on two large cross-sectional cohorts of children, one from Tanzania and the other from the United States (N = 7,173). We employ 3D facial imaging and geometric morphometrics to relate facial shape to age and anthropometric measures. The two populations differ significantly in facial shape, but the magnitude of this difference is small relative to the variation within each group. Allometric variation for facial shape is similar in both populations, representing a small but significant proportion of total variation in facial shape. Different measures of size are associated with overlapping but statistically distinct aspects of shape variation. Only half of the size-related variation in facial shape can be explained by the first principal component of four size measures and age while the remainder associates distinctly with individual measures. Allometric variation in the human face is complex and should not be regarded as a singular effect. This finding has important implications for how size is treated in studies of human facial shape and for the developmental basis for allometric variation more generally. © 2017 Wiley Periodicals, Inc.

Economic stress or random variation? Revisiting German reunification as a natural experiment to investigate the effect of economic contraction on sex ratios at birth.

PubMed

Schnettler, Sebastian; Klüsener, Sebastian

2014-12-22

The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SRB) following economic decline. However, as many factors influence the SRB, this hypothesis is difficult to test empirically. Thus, researchers make use of quasi-experiments such as German reunification: The economy in East, but not in West Germany, underwent a rapid decline in 1991. A co-occurrence of a decline in the East German SRB in 1991 has been interpreted by some as support for the ESH. However, another explanation might be that the low SRB in 1991 stems from increased random variation in the East German SRB due to a drastically reduced number of births during the crisis. We look into this alternative random variation hypothesis (RVH) by re-examining the German case with more detailed data. Our analysis has two parts. First, using aggregate-level birth register data for all births in the period between 1946 and 2011, we plot the quantum and variance of the SRB and the number of births and unemployment rates, separately for East and West Germany, and conduct a time series analysis on the East German SRB over time. Second, we model the odds for a male birth at the individual level in a multiple logistic regression (1991-2010, ~13.9 million births). Explanatory variables are related to the level of the individual birth, the mother of the child born, and the regional economic context. The aggregate-level analysis reveals a higher degree of variation of the SRB in East Germany. Deviations from the time trend occur in several years, seemingly unrelated to economic development, and the deviation in 1991 is not statistically significant. The individual-level analysis confirms that the 1991-drop in the East German SRB cannot directly be attributed to economic development and that there is no statistically significant effect of economic development on sex determination in East or West Germany. Outcomes support the RVH but not the ESH. Furthermore, our results speak against a statistically significant effect of the reunification event itself on the East German SRB. We discuss the relative importance of behavioral and physiological responses to macro-level stressors, a distinction that may help integrate previously mixed findings.

Alternative Derivations of the Statistical Mechanical Distribution Laws

PubMed Central

Wall, Frederick T.

1971-01-01

A new approach is presented for the derivation of statistical mechanical distribution laws. The derivations are accomplished by minimizing the Helmholtz free energy under constant temperature and volume, instead of maximizing the entropy under constant energy and volume. An alternative method involves stipulating equality of chemical potential, or equality of activity, for particles in different energy levels. This approach leads to a general statement of distribution laws applicable to all systems for which thermodynamic probabilities can be written. The methods also avoid use of the calculus of variations, Lagrangian multipliers, and Stirling's approximation for the factorial. The results are applied specifically to Boltzmann, Fermi-Dirac, and Bose-Einstein statistics. The special significance of chemical potential and activity is discussed for microscopic systems. PMID:16578712

Alternative derivations of the statistical mechanical distribution laws.

PubMed

Wall, F T

1971-08-01

A new approach is presented for the derivation of statistical mechanical distribution laws. The derivations are accomplished by minimizing the Helmholtz free energy under constant temperature and volume, instead of maximizing the entropy under constant energy and volume. An alternative method involves stipulating equality of chemical potential, or equality of activity, for particles in different energy levels. This approach leads to a general statement of distribution laws applicable to all systems for which thermodynamic probabilities can be written. The methods also avoid use of the calculus of variations, Lagrangian multipliers, and Stirling's approximation for the factorial. The results are applied specifically to Boltzmann, Fermi-Dirac, and Bose-Einstein statistics. The special significance of chemical potential and activity is discussed for microscopic systems.

The influence of depression and anxiety in the development of heart failure after coronary angioplasty.

PubMed

Gegenava, T; Gegenava, M; Kavtaradze, G

2009-03-01

The aim of our study was to investigate the association between history of depressive episode and anxiety and complications in patients after 6 months of coronary artery angioplasty. The research was conducted on 70 patients, the grade of coronary occlusion that would not respond to therapeutic treatment and need coronary angioplasty had been established. Complications were estimated in 60 patients after 6 months of coronary angioplasty. To evaluate depression we used Beck depression scale Anxiety was assessed by Spilberger State-trait anxiety scale. Statistic analysis of the data was made by means of the methods of variation statistics using Students' criterion and program of STATISTICA w 5.0. Complications were discovered in 36 (60%) patients; 24 (40%) patients had not complications. There was not revealed significant statistical differences in depression and anxiety degree in coronary angioplasty period and after 6 months of coronary angioplasty. There was not revealed significant statistical differences in depression and anxiety degree in coronary angioplasty period and after 6 months of coronary angioplasty. Our study demonstrated that complications were revealed in patients who had high degree of depression and anxiety.

Development and Validation of a Statistical Shape Modeling-Based Finite Element Model of the Cervical Spine Under Low-Level Multiple Direction Loading Conditions

PubMed Central

Bredbenner, Todd L.; Eliason, Travis D.; Francis, W. Loren; McFarland, John M.; Merkle, Andrew C.; Nicolella, Daniel P.

2014-01-01

Cervical spinal injuries are a significant concern in all trauma injuries. Recent military conflicts have demonstrated the substantial risk of spinal injury for the modern warfighter. Finite element models used to investigate injury mechanisms often fail to examine the effects of variation in geometry or material properties on mechanical behavior. The goals of this study were to model geometric variation for a set of cervical spines, to extend this model to a parametric finite element model, and, as a first step, to validate the parametric model against experimental data for low-loading conditions. Individual finite element models were created using cervical spine (C3–T1) computed tomography data for five male cadavers. Statistical shape modeling (SSM) was used to generate a parametric finite element model incorporating variability of spine geometry, and soft-tissue material property variation was also included. The probabilistic loading response of the parametric model was determined under flexion-extension, axial rotation, and lateral bending and validated by comparison to experimental data. Based on qualitative and quantitative comparison of the experimental loading response and model simulations, we suggest that the model performs adequately under relatively low-level loading conditions in multiple loading directions. In conclusion, SSM methods coupled with finite element analyses within a probabilistic framework, along with the ability to statistically validate the overall model performance, provide innovative and important steps toward describing the differences in vertebral morphology, spinal curvature, and variation in material properties. We suggest that these methods, with additional investigation and validation under injurious loading conditions, will lead to understanding and mitigating the risks of injury in the spine and other musculoskeletal structures. PMID:25506051

Geographic variations in avoidable hospitalizations in the elderly, in a health system with universal coverage

PubMed Central

Magan, Purificacion; Otero, Angel; Alberquilla, Angel; Ribera, Jose Manuel

2008-01-01

Background The study of Hospitalizations for ambulatory care sensitive conditions (ACSH) has been proposed as an indirect measure of access to and receipt of care by older persons at the entryway to the Spanish public health system. The aim of this work is to identify the rates of ACSH in persons 65 years or older living in different small-areas of the Community of Madrid (CM) and to detect possible differences in ACSH. Methods Cross-sectional, ecologic study, which covered all 34 health districts of the CM. The study population consisted of all individuals aged 65 years or older residing in the CM between 2001 and 2003, inclusive. Using hospital discharge data, avoidable ACSH were selected from the list of conditions validated for Spain. Age- and sex-adjusted ACSH rates were calculated for the population of each health district and the statistics describing the data variability. Point graphs and maps were designed to represent the ACSH rates in the different health districts. Results Of all the hospitalizations, 16.5% (64,409) were ACSH. Globally, the rate was higher among men: 33.15 per 1,000 populations vs. 22.10 in women and these differences were statistically significant (p < 0.05) in each district. For men the range was 70.82 and the coefficient of variation (CV) was 0.47, while for women the range was 43.69 and the CV was 0.48. In 93.1% of cases, the ACSH were caused by hypertensive cardiovascular disease, heart failure or pneumonia. A centripetal pattern can be observed, with lower rates in the districts in the center of the CM. This geographic distribution is maintained after grouping by sex. Conclusion A significant variation is demonstrated in "preventable" hospitalizations between the different districts. In all the districts the men present rates significantly higher than women. Important variations in the access are observed the Primary Attention in spite of existing a universal sanitary cover. PMID:18282282

Individual tree differences confound effects of growth regulators in rooting sugar maple softwood cuttings

Treesearch

John R. Donnelly

1971-01-01

Softwood stem cuttings from three mature sugar maple trees were treated with several types and concentrations of growth regulators. Lack of statistical significance was due to extreme variability in tree response: low levels of auxin stimulated rooting in two study trees, while auxins inhibited rooting in the other tree. It is postulated that variations in rooting...

First results of the magnetic field measurements on the G0 IV η Boo

NASA Astrophysics Data System (ADS)

Butkovskaya, V. V.; Plachinda, S. I.; Baklanova, D.; Pankov, N. F.

2018-01-01

Search for a magnetic field on η Boo has been performed over 50 nights in 1999 — 2014. Statistically significant magnetic field has been detected over 5 out of 50 nights. The total range of the longitudinal magnetic field variations is from -15.1±6.4 G to 23.1±9.6 G.

Three-Year Change in the Wellbeing of Orphaned and Separated Children in Institutional and Family-Based Care Settings in Five Low- and Middle-Income Countries

PubMed Central

Whetten, Kathryn; Ostermann, Jan; Pence, Brian W.; Whetten, Rachel A.; Messer, Lynne C.; Ariely, Sumedha; O'Donnell, Karen; Wasonga, Augustine I.; Vann, Vanroth; Itemba, Dafrosa; Eticha, Misganaw; Madan, Ira; Thielman, Nathan M.

2014-01-01

Background With more than 2 million children living in group homes, or “institutions”, worldwide, the extent to which institution-based caregiving negatively affects development and wellbeing is a central question for international policymakers. Methods A two-stage random sampling methodology identified community representative samples of 1,357 institution-dwelling orphaned and separated children (OSC) and 1,480 family-dwelling OSC aged 6–12 from 5 low and middle income countries. Data were collected from children and their primary caregivers. Survey-analytic techniques and linear mixed effects models describe child wellbeing collected at baseline and at 36 months, including physical and emotional health, growth, cognitive development and memory, and the variation in outcomes between children, care settings, and study sites. Findings At 36-month follow-up, institution-dwelling OSC had statistically significantly higher height-for-age Z-scores and better caregiver-reported physical health; family-dwelling OSC had fewer caregiver-reported emotional difficulties. There were no statistically significant differences between the two groups on other measures. At both baseline and follow-up, the magnitude of the differences between the institution- and family-dwelling groups was small. Relatively little variation in outcomes was attributable to differences between sites (11–27% of total variation) or care settings within sites (8–14%), with most variation attributable to differences between children within settings (60–75%). The percent of variation in outcomes attributable to the care setting type, institution- versus family-based care, ranged from 0–4% at baseline, 0–3% at 36-month follow-up, and 0–4% for changes between baseline and 36 months. Interpretation These findings contradict the hypothesis that group home placement universally adversely affects child wellbeing. Without substantial improvements in and support for family settings, the removal of institutions, broadly defined, would not significantly improve child wellbeing and could worsen outcomes of children who are moved from a setting where they are doing relatively well to a more deprived setting. PMID:25162410

Serum immunoreactive erythropoietin in high altitude natives with and without excessive erythrocytosis.

PubMed

León-Velarde, F; Monge, C C; Vidal, A; Carcagno, M; Criscuolo, M; Bozzini, C E

1991-05-01

We report the estimation of blood hemoglobin (Hb), arterial blood oxygen saturation (SaO2), and serum immunoreactive erythropoietin (siEPO) in a group of Peruvian workers residing in Cerro de Pasco at 4300 m showing "excessive erythrocytosis" (EE, Monge's disease, chronic mountain sickness). These estimates were compared with those of humans residing either in Cerro de Pasco and showing "normal erythrocytosis" (NE) or in Lima (sea level, SL) to determine whether Hb and SaO2 are related to siEPO in high altitude (HA) natives with NE or EE. The three parameters showed statistically significant differences between HA and SL groups--the values in SL being lower. Significant differences were also found between NE and EE groups in Hb and SaO2. There was no statistical difference in siEPo between the two groups. The results indicate, therefore, that HA residents who develop EE are not distinguishable from residents who develop NE on the basis of estimates of siEPO. As a result, siEPO and Hb do not show a dose-response relationship in HA residents, and variation in EPO does not explain the striking variation in Hb at high altitudes.

Reducing the standard deviation in multiple-assay experiments where the variation matters but the absolute value does not.

PubMed

Echenique-Robba, Pablo; Nelo-Bazán, María Alejandra; Carrodeguas, José A

2013-01-01

When the value of a quantity x for a number of systems (cells, molecules, people, chunks of metal, DNA vectors, so on) is measured and the aim is to replicate the whole set again for different trials or assays, despite the efforts for a near-equal design, scientists might often obtain quite different measurements. As a consequence, some systems' averages present standard deviations that are too large to render statistically significant results. This work presents a novel correction method of a very low mathematical and numerical complexity that can reduce the standard deviation of such results and increase their statistical significance. Two conditions are to be met: the inter-system variations of x matter while its absolute value does not, and a similar tendency in the values of x must be present in the different assays (or in other words, the results corresponding to different assays must present a high linear correlation). We demonstrate the improvements this method offers with a cell biology experiment, but it can definitely be applied to any problem that conforms to the described structure and requirements and in any quantitative scientific field that deals with data subject to uncertainty.

Functional effects of CCL3L1 copy number.

PubMed

Carpenter, D; McIntosh, R S; Pleass, R J; Armour, J A L

2012-07-01

Copy number variation (CNV) is becoming increasingly important as a feature of human variation in disease susceptibility studies. However, the consequences of CNV are not so well understood. Here, we present data exploring the functional consequences of CNV of CCL3L1 in 55 independent UK samples with no known clinical phenotypes. The copy number of CCL3L1 was determined by the paralogue ratio test, and expression levels of macrophage inflammatory protein-1α (MIP-1α) and mRNA from stimulated monocytes were measured and analysed. The data show no statistically significant association of MIP-1α protein levels with copy number. However, there was a significant correlation between copy number and CCL3L1:CCL3 mRNA ratio. The data also provide evidence that expression of CCL3 predominates in both protein and mRNA, and therefore the observed variation of CCL3 is potentially more important biologically than that of CNV of CCL3L1.

Variations in neutrophil count in preterm infants with respiratory distress syndrome who subsequently developed chronic lung disease.

PubMed

Kohelet, D; Arbel, E; Ballin, A; Goldberg, M

2000-01-01

Neutrophil counts were studied in 62 preterm infants receiving mechanical ventilation for neonatal respiratory distress syndrome (NRDS). Exploratory analysis indicated that the severity of NRDS, as demonstrated by fractional inspired oxygen (FiO2), mean airway pressure (MAP), arterial-alveolar PO2 ratio (a/APO2) and oxygenation index (OI), was correlated with percentage change of neutrophil counts during the first 5 days of life. Further analysis demonstrated that infants with NRDS who subsequently developed chronic lung disease (CLD) (n = 21) had statistically significant differences in variation of neutrophil counts when compared with the remainder (n = 41) without CLD (-35.0% +/- 4.3 vs. -16.9% +/- 5.8, p < 0.02). It is concluded that significant variations in neutrophil counts during the first 5 days of life may be found in infants with NRDS who subsequently develop CLD and that these changes may have predictive value regarding the development of CLD.

Size Variation under Domestication: Conservatism in the inner ear shape of wolves, dogs and dingoes.

PubMed

Schweizer, Anita V; Lebrun, Renaud; Wilson, Laura A B; Costeur, Loïc; Schmelzle, Thomas; Sánchez-Villagra, Marcelo R

2017-10-17

A broad sample of wolves, dingoes, and domesticated dogs of different kinds and time periods was used to identify changes in size and shape of the organs of balance and hearing related to domestication and to evaluate the potential utility of uncovered patterns as markers of domestication. Using geometric morphometrics coupled with non-invasive imaging and three-dimensional reconstructions, we exposed and compared complex structures that remain largely conserved. There is no statistically significant difference in the levels of shape variation between prehistoric and modern dogs. Shape variance is slightly higher for the different components of the inner ear in modern dogs than in wolves, but these differences are not significant. Wolves express a significantly greater level of variance in the angle between the lateral and the posterior canal than domestic dog breeds. Wolves have smaller levels of size variation than dogs. In terms of the shape of the semicircular canals, dingoes reflect the mean shape in the context of variation in the sample. This mirrors the condition of feral forms in other organs, in which there is an incomplete return to the characteristics of the ancestor. In general, morphological diversity or disparity in the inner ear is generated by scaling.

Statistical analysis of environmental variability within the CELSS breadboard project's biomass production chamber

NASA Technical Reports Server (NTRS)

Stutte, G. W.; Chetirkin, P. V.; Mackowiak, C. L.; Fortson, R. E.

1993-01-01

Variability in the aerial and root environments of NASA's Breadboard Project's Biomass Production Chamber (BPC) was determined. Data from two lettuce and two potato growouts were utilized. One growout of each crop was conducted prior to separating the upper and lower chambers; the other was subsequent to separation. There were little or no differences in pH, EC, or solution temperature between the upper and lower chamber or within a chamber. Variation in the aerial environment within a chamber was two to three times greater than variation between chambers for air temperature, relative humidity, and PPF. High variability in air velocity, relative to tray position, was observed. Separating the BPC had no effect on PPF, air velocity, solution temperature, pH, or EC. Separation reduced the gradient in air temperature and relative humidity between the upper and lower chambers, but increased the variability within a chamber. Variation between upper and lower chambers was within 5 percent of environmental set-points and of little or no physiological significance. In contrast, the variability within a chamber limits the capability of the BPC to generate statistically reliable data from individual tray treatments at this time.

Note Onset Deviations as Musical Piece Signatures

PubMed Central

Serrà, Joan; Özaslan, Tan Hakan; Arcos, Josep Lluis

2013-01-01

A competent interpretation of a musical composition presents several non-explicit departures from the written score. Timing variations are perhaps the most important ones: they are fundamental for expressive performance and a key ingredient for conferring a human-like quality to machine-based music renditions. However, the nature of such variations is still an open research question, with diverse theories that indicate a multi-dimensional phenomenon. In the present study, we consider event-shift timing variations and show that sequences of note onset deviations are robust and reliable predictors of the musical piece being played, irrespective of the performer. In fact, our results suggest that only a few consecutive onset deviations are already enough to identify a musical composition with statistically significant accuracy. We consider a mid-size collection of commercial recordings of classical guitar pieces and follow a quantitative approach based on the combination of standard statistical tools and machine learning techniques with the semi-automatic estimation of onset deviations. Besides the reported results, we believe that the considered materials and the methodology followed widen the testing ground for studying musical timing and could open new perspectives in related research fields. PMID:23935971

Radionuclide concentration variations in the fuel and residues of oil shale-fired power plants: Estimations of the radiological characteristics over a 2-year period.

PubMed

Vaasma, Taavi; Loosaar, Jüri; Kiisk, Madis; Tkaczyk, Alan Henry

2017-07-01

Several multi-day samplings were conducted over a 2-year period from an oil shale-fired power plant operating with pulverized fuel type of boilers that were equipped with either novel integrated desulphurization system and bag filters or with electrostatic precipitators. Oil shale, bottom ash and fly ash samples were collected and radionuclides from the 238 U and 232 Th series as well as 40 K were determined. The work aimed at determining possible variations in the concentrations of naturally occurring radionuclides within the collected samples and detect the sources of these fluctuations. During the continuous multi-day samplings, various boiler parameters were recorded as well. With couple of exceptions, no statistically significant differences were detected (significance level 0.05) between the measured radionuclide mean values in various ash samples within the same sampling. When comparing the results between multiple years and samplings, no statistically significant variations were observed between 238 U and 226 Ra values. However, there were significant differences between the values in the fly ashes when comparing 210 Pb, 40 K, 228 Ra and 232 Th values between the various samplings. In all cases the radionuclide activity concentrations in the specific fly ash remained under 100 Bq kg -1 , posing no radiological concerns when using this material as an additive in construction or building materials. Correlation analysis between the registered boiler parameters and measured radionuclide activity concentrations showed weak or no correlation. The obtained results suggest that the main sources of variations are due to the characteristics of the used fuel. The changes in the radionuclide activity concentrations between multiple years were in general rather modest. The radionuclide activity concentrations varied dominantly between 4% and 15% from the measured mean within the same sampling. The relative standard deviation was however within the same range as the relative measurement uncertainty, suggesting that the main component of fluctuations is derived from the measurement method and approach. The obtained results indicate that representativeness of the data over a longer time period is valid only when a fuel with a similar composition is used and when the combustion boilers operate with a uniform setup (same boiler type and purification system). The results and the accompanying statistical analysis clearly demonstrated that in order to obtain data with higher reliability, a repeated multi-day sampling should be organized and combined with the registered boiler technical and operational parameters. Copyright © 2016 Elsevier Ltd. All rights reserved.

A scan statistic to extract causal gene clusters from case-control genome-wide rare CNV data.

PubMed

Nishiyama, Takeshi; Takahashi, Kunihiko; Tango, Toshiro; Pinto, Dalila; Scherer, Stephen W; Takami, Satoshi; Kishino, Hirohisa

2011-05-26

Several statistical tests have been developed for analyzing genome-wide association data by incorporating gene pathway information in terms of gene sets. Using these methods, hundreds of gene sets are typically tested, and the tested gene sets often overlap. This overlapping greatly increases the probability of generating false positives, and the results obtained are difficult to interpret, particularly when many gene sets show statistical significance. We propose a flexible statistical framework to circumvent these problems. Inspired by spatial scan statistics for detecting clustering of disease occurrence in the field of epidemiology, we developed a scan statistic to extract disease-associated gene clusters from a whole gene pathway. Extracting one or a few significant gene clusters from a global pathway limits the overall false positive probability, which results in increased statistical power, and facilitates the interpretation of test results. In the present study, we applied our method to genome-wide association data for rare copy-number variations, which have been strongly implicated in common diseases. Application of our method to a simulated dataset demonstrated the high accuracy of this method in detecting disease-associated gene clusters in a whole gene pathway. The scan statistic approach proposed here shows a high level of accuracy in detecting gene clusters in a whole gene pathway. This study has provided a sound statistical framework for analyzing genome-wide rare CNV data by incorporating topological information on the gene pathway.

Climate variation explains a third of global crop yield variability

PubMed Central

Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

2015-01-01

Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32–39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability. PMID:25609225

Correlations for number of sunspots, unemployment rate, and suicide mortality in Japan.

PubMed

Otsu, Akiko; Chinami, Masanobu; Morgenthale, Stephan; Kaneko, Yoshihiro; Fujita, Daisuke; Shirakawa, Taro

2006-04-01

We studied the correlations among sunspot numbers, business cycles, and suicide mortalitites. Based on data from Japan between 1971 and 2001, a significant negative correlation between sunspot numbers and unemployment rate was found, R= -.17. The correlation between suicide mortality and unemployment rate was positive for males (R=.46) and negative for females (R =-.69). Both are statistically significant. The hypothesis that variation of sun activity may affect the economy and the unemployment rate and hence increase the male suicide mortality is raised.

Polymorphisms in the FGF2 gene and risk of serous ovarian cancer: results from the Ovarian Cancer Association Consortium

PubMed Central

Johnatty, Sharon E.; Beesley, Jonathan; Chen, Xiaoqing; Spurdle, Amanda B.; deFazio, Anna; Webb, Penelope M; Goode, Ellen L.; Rider, David N.; Vierkant, Robert A.; Anderson, Stephanie; Wu, Anna H.; Pike, Malcolm; Van Den Berg, David; Moysich, Kirsten; Ness, Roberta; Doherty, Jennifer; Rossing, Mary-Anne; Pearce, Celeste Leigh; Chenevix-Trench, Georgia

2009-01-01

Fibroblast growth factor (FGF)-2 (basic) is a potent angiogenic molecule involved in tumour progression, and is one of several growth factors with a central role in ovarian carcinogenesis. We hypothesised that common single nucleotide polymorphisms (SNPs) in the FGF2 gene may alter angiogenic potential and thereby susceptibility to ovarian cancer. We analysed 25 FGF2 tgSNPs using five independent study populations from the United States and Australia. Analysis was restricted to non-Hispanic White women with serous ovarian carcinoma (1269 cases and 2829 controls). There were no statistically significant associations between any FGF2 SNPs and ovarian cancer risk. There were two nominally statistically significant associations between heterozygosity for two FGF2 SNPs (rs308379 and rs308447; p<0.05) and serous ovarian cancer risk in the combined dataset, but rare homozygous estimates did not achieve statistical significance, nor were they consistent with the log additive model of inheritance. Overall genetic variation in FGF2 does not appear to play a role in susceptibility to ovarian cancer. PMID:19456219

A statistical human rib cage geometry model accounting for variations by age, sex, stature and body mass index.

PubMed

Shi, Xiangnan; Cao, Libo; Reed, Matthew P; Rupp, Jonathan D; Hoff, Carrie N; Hu, Jingwen

2014-07-18

In this study, we developed a statistical rib cage geometry model accounting for variations by age, sex, stature and body mass index (BMI). Thorax CT scans were obtained from 89 subjects approximately evenly distributed among 8 age groups and both sexes. Threshold-based CT image segmentation was performed to extract the rib geometries, and a total of 464 landmarks on the left side of each subject׳s ribcage were collected to describe the size and shape of the rib cage as well as the cross-sectional geometry of each rib. Principal component analysis and multivariate regression analysis were conducted to predict rib cage geometry as a function of age, sex, stature, and BMI, all of which showed strong effects on rib cage geometry. Except for BMI, all parameters also showed significant effects on rib cross-sectional area using a linear mixed model. This statistical rib cage geometry model can serve as a geometric basis for developing a parametric human thorax finite element model for quantifying effects from different human attributes on thoracic injury risks. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spatial variation in hyperthermia emergency department visits among those with employer-based insurance in the United States - a case-crossover analysis.

PubMed

Saha, Shubhayu; Brock, John W; Vaidyanathan, Ambarish; Easterling, David R; Luber, George

2015-03-04

Predictions of intense heat waves across the United States will lead to localized health impacts, most of which are preventable. There is a need to better understand the spatial variation in the morbidity impacts associated with extreme heat across the country to prevent such adverse health outcomes. Hyperthermia-related emergency department (ED) visits were obtained from the Truven Health MarketScan(®) Research dataset for 2000-2010. Three measures of daily ambient heat were constructed using meteorological observations from the National Climatic Data Center (maximum temperature, heat index) and the Spatial Synoptic Classification. Using a time-stratified case crossover approach, odds ratio of hyperthermia-related ED visit were estimated for the three different heat measures. Random effects meta-analysis was used to combine the odds ratios for 94 Metropolitan Statistical Areas (MSA) to examine the spatial variation by eight latitude categories and nine U.S. climate regions. Examination of lags for all three temperature measures showed that the odds ratio of ED visit was statistically significant and highest on the day of the ED visit. For heat waves lasting two or more days, additional statistically significant association was observed when heat index and synoptic classification was used as the temperature measure. These results were insensitive to the inclusion of air pollution measures. On average, the maximum temperature on the day of an ED visit was 93.4°F in 'South' and 81.9°F in the 'Northwest' climatic regions of United States. The meta-analysis showed higher odds ratios of hyperthermia ED visit in the central and the northern parts of the country compared to the south and southwest. The results showed spatial variation in average temperature on days of ED visit and odds ratio for hyperthermia ED visits associated with extreme heat across United States. This suggests that heat response plans need to be customized for different regions and the potential role of hyperthermia ED visits in syndromic surveillance for extreme heat.

The effects of different concentrations of cocoa in the chocolate intaken by the mother on fetal heart rate.

PubMed

Buscicchio, Giorgia; Lorenzi, Sara; Tranquilli, Andrea Luigi

2013-10-01

To analyze the effects of different concentrations (30% and 80%) of cocoa on fetal heart rate (FHR). One hundred pregnant women with uncomplicated gestation, matched for age and parity, underwent computerized FHR recording before and after the consumption of 30 g of 30% and 80% cocoa chocolate. After 1 week, those who had received 30% were shifted to 80% and vice versa to have a crossover. Computerized cardiotocography parameters (contractions, fetal movements, baseline FHR, accelerations greater than 15 bpm for 15 s, number of decelerations, minutes of high variability, short term variability in ms) were recorded and expressed as mean and SD. The differences were tested for statistical significance using the paired t test, with the significance at p < 0.05. The percent change after chocolate intake for accelerations and short-term FHR variation was calculated. The number of fetal movements, accelerations, the duration of episodes of high variation and the short-term FHR variation were significantly higher (p < 0.0001) after 80% cocoa intake. After 30% cocoa chocolate intake, only the number of accelerations was significantly increased. The percent change of the number of accelerations and the short-term FHR variation were significantly higher after 80% cocoa chocolate maternal intake. Maternal intake of dark chocolate has a stimulating action on fetal reactivity. The effect is more marked with high concentrations (80%) of cocoa. This finding is likely due to the pharmacological action of theobromine, a methilxanthine present in cocoa.

Accuracy, repeatability, and reproducibility of Artemis very high-frequency digital ultrasound arc-scan lateral dimension measurements

PubMed Central

Reinstein, Dan Z.; Archer, Timothy J.; Silverman, Ronald H.; Coleman, D. Jackson

2008-01-01

Purpose To determine the accuracy, repeatability, and reproducibility of measurement of lateral dimensions using the Artemis (Ultralink LLC) very high-frequency (VHF) digital ultrasound (US) arc scanner. Setting London Vision Clinic, London, United Kingdom. Methods A test object was measured first with a micrometer and then with the Artemis arc scanner. Five sets of 10 consecutive B-scans of the test object were performed with the scanner. The test object was removed from the system between each scan set. One expert observer and one newly trained observer separately measured the lateral dimension of the test object. Two-factor analysis of variance was performed. The accuracy was calculated as the average bias of the scan set averages. The repeatability and reproducibility coefficients were calculated. The coefficient of variation (CV) was calculated for repeatability and reproducibility. Results The test object was measured to be 10.80 mm wide. The mean lateral dimension bias was 0.00 mm. The repeatability coefficient was 0.114 mm. The reproducibility coefficient was 0.026 mm. The repeatability CV was 0.38%, and the reproducibility CV was 0.09%. There was no statistically significant variation between observers (P = .0965). There was a statistically significant variation between scan sets (P = .0036) attributed to minor vertical changes in the alignment of the test object between consecutive scan sets. Conclusion The Artemis VHF digital US arc scanner obtained accurate, repeatable, and reproducible measurements of lateral dimensions of the size commonly found in the anterior segment. PMID:17081860

Conditional Random Fields for Fast, Large-Scale Genome-Wide Association Studies

PubMed Central

Huang, Jim C.; Meek, Christopher; Kadie, Carl; Heckerman, David

2011-01-01

Understanding the role of genetic variation in human diseases remains an important problem to be solved in genomics. An important component of such variation consist of variations at single sites in DNA, or single nucleotide polymorphisms (SNPs). Typically, the problem of associating particular SNPs to phenotypes has been confounded by hidden factors such as the presence of population structure, family structure or cryptic relatedness in the sample of individuals being analyzed. Such confounding factors lead to a large number of spurious associations and missed associations. Various statistical methods have been proposed to account for such confounding factors such as linear mixed-effect models (LMMs) or methods that adjust data based on a principal components analysis (PCA), but these methods either suffer from low power or cease to be tractable for larger numbers of individuals in the sample. Here we present a statistical model for conducting genome-wide association studies (GWAS) that accounts for such confounding factors. Our method scales in runtime quadratic in the number of individuals being studied with only a modest loss in statistical power as compared to LMM-based and PCA-based methods when testing on synthetic data that was generated from a generalized LMM. Applying our method to both real and synthetic human genotype/phenotype data, we demonstrate the ability of our model to correct for confounding factors while requiring significantly less runtime relative to LMMs. We have implemented methods for fitting these models, which are available at http://www.microsoft.com/science. PMID:21765897

Tsallis non-extensive statistical mechanics in the ionospheric detrended total electron content during quiet and storm periods

NASA Astrophysics Data System (ADS)

Ogunsua, B. O.; Laoye, J. A.

2018-05-01

In this paper, the Tsallis non-extensive q-statistics in ionospheric dynamics was investigated using the total electron content (TEC) obtained from two Global Positioning System (GPS) receiver stations. This investigation was carried out considering the geomagnetically quiet and storm periods. The micro density variation of the ionospheric total electron content was extracted from the TEC data by method of detrending. The detrended total electron content, which represent the variation in the internal dynamics of the system was further analyzed using for non-extensive statistical mechanics using the q-Gaussian methods. Our results reveals that for all the analyzed data sets the Tsallis Gaussian probability distribution (q-Gaussian) with value q > 1 were obtained. It was observed that there is no distinct difference in pattern between the values of qquiet and qstorm. However the values of q varies with geophysical conditions and possibly with local dynamics for the two stations. Also observed are the asymmetric pattern of the q-Gaussian and a highly significant level of correlation for the q-index values obtained for the storm periods compared to the quiet periods between the two GPS receiver stations where the TEC was measured. The factors responsible for this variation can be mostly attributed to the varying mechanisms resulting in the self-reorganization of the system dynamics during the storm periods. The result shows the existence of long range correlation for both quiet and storm periods for the two stations.

Tests of linkage and/or association of the LEPR gene polymorphisms with obesity phenotypes in Caucasian nuclear families.

PubMed

Liu, Yong-Jun; Rocha-Sanchez, Sonia M S; Liu, Peng-Yuan; Long, Ji-Rong; Lu, Yan; Elze, Leo; Recker, Robert R; Deng, Hong-Wen

2004-04-13

Genetic variations in the leptin receptor (LEPR) gene have been conceived to affect body weight in general populations. In this study, using the tests implemented in the statistical package QTDT, we evaluated association and/or linkage of the LEPR gene with obesity phenotypes in a large sample comprising 1,873 subjects from 405 Caucasian nuclear families. Obesity phenotypes tested include body mass index (BMI), fat mass, percentage fat mass (PFM), and lean mass, with the latter three measured by dual-energy X-ray absorptiometry (DXA). Three single nucleotide polymorphisms (SNPs), namely Lys109Arg (A/G), Lys656Asn (G/C), Pro1019Pro (G/A), in the LEPR gene were analyzed. Significant linkage disequilibrium (0.394 < or = |D'| < or = 0.688, P < 0.001) was observed between pairs of the three SNPs. No significant population stratification was found for any SNP/phenotype. In single-locus analyses, evidence of association was observed for Lys656Asn with lean mass (P = 0.002) and fat mass (P = 0.015). The contribution of this polymorphism to the phenotypic variation of lean mass and fat mass was 2.63% and 1.15%, respectively. Subjects carrying allele G at the Lys656Asn site had, on average, 3.16% higher lean mass and 2.71% higher fat mass than those without it. In the analyses for haplotypes defined by the three SNPs, significant associations were detected between haplotype GCA (P = 0.005) and lean mass. In addition, marginally significant evidence of association was observed for this haplotype with fat mass (P = 0.012). No statistically significant linkage was found, largely due to the limited power of the linkage approach to detect small genetic effects in our data sets. Our results suggest that the LEPR gene polymorphisms contribute to variation in obesity phenotypes.

Three-dimensional analysis of magnetometer array data

NASA Technical Reports Server (NTRS)

Richmond, A. D.; Baumjohann, W.

1984-01-01

A technique is developed for mapping magnetic variation fields in three dimensions using data from an array of magnetometers, based on the theory of optimal linear estimation. The technique is applied to data from the Scandinavian Magnetometer Array. Estimates of the spatial power spectra for the internal and external magnetic variations are derived, which in turn provide estimates of the spatial autocorrelation functions of the three magnetic variation components. Statistical errors involved in mapping the external and internal fields are quantified and displayed over the mapping region. Examples of field mapping and of separation into external and internal components are presented. A comparison between the three-dimensional field separation and a two-dimensional separation from a single chain of stations shows that significant differences can arise in the inferred internal component.

The relationship between particulate pollution levels in Australian cities, meteorology, and landscape fire activity detected from MODIS hotspots.

PubMed

Price, Owen F; Williamson, Grant J; Henderson, Sarah B; Johnston, Fay; Bowman, David M J S

2012-01-01

Smoke from bushfires is an emerging issue for fire managers because of increasing evidence for its public health effects. Development of forecasting models to predict future pollution levels based on the relationship between bushfire activity and current pollution levels would be a useful management tool. As a first step, we use daily thermal anomalies detected by the MODIS Active Fire Product (referred to as "hotspots"), pollution concentrations, and meteorological data for the years 2002 to 2008, to examine the statistical relationship between fire activity in the landscapes and pollution levels around Perth and Sydney, two large Australian cities. Resultant models were statistically significant, but differed in their goodness of fit and the distance at which the strength of the relationship was strongest. For Sydney, a univariate model for hotspot activity within 100 km explained 24% of variation in pollution levels, and the best model including atmospheric variables explained 56% of variation. For Perth, the best radius was 400 km, explaining only 7% of variation, while the model including atmospheric variables explained 31% of the variation. Pollution was higher when the atmosphere was more stable and in the presence of on-shore winds, whereas there was no effect of wind blowing from the fires toward the pollution monitors. Our analysis shows there is a good prospect for developing region-specific forecasting tools combining hotspot fire activity with meteorological data.

Detection and quantification of creep strain using process compensated resonance testing (PCRT) sorting modules trained with modeled resonance spectra

NASA Astrophysics Data System (ADS)

Heffernan, Julieanne; Biedermann, Eric; Mayes, Alexander; Livings, Richard; Jauriqui, Leanne; Goodlet, Brent; Aldrin, John C.; Mazdiyasni, Siamack

2018-04-01

Process Compensated Resonant Testing (PCRT) is a full-body nondestructive testing (NDT) method that measures the resonance frequencies of a part and correlates them to the part's material and/or damage state. PCRT testing is used in the automotive, aerospace, and power generation industries via automated PASS/FAIL inspections to distinguish parts with nominal process variation from those with the defect(s) of interest. Traditional PCRT tests are created through the statistical analysis of populations of "good" and "bad" parts. However, gathering a statistically significant number of parts can be costly and time-consuming, and the availability of defective parts may be limited. This work uses virtual databases of good and bad parts to create two targeted PCRT inspections for single crystal (SX) nickel-based superalloy turbine blades. Using finite element (FE) models, populations were modeled to include variations in geometric dimensions, material properties, crystallographic orientation, and creep damage. Model results were verified by comparing the frequency variation in the modeled populations with the measured frequency variations of several physical blade populations. Additionally, creep modeling results were verified through the experimental evaluation of coupon geometries. A virtual database of resonance spectra was created from the model data. The virtual database was used to create PCRT inspections to detect crystallographic defects and creep strain. Quantification of creep strain values using the PCRT inspection results was also demonstrated.

Dental Workforce Availability and Dental Services Utilization in Appalachia: A Geospatial Analysis

PubMed Central

Feng, Xue; Sambamoorthi, Usha; Wiener, R. Constance

2016-01-01

Objectives There is considerable variation in dental services utilization across Appalachian counties, and a plausible explanation is that individuals in some geographical areas do not utilize dental care due to dental workforce shortage. We conducted an ecological study on dental workforce availability and dental services utilization in Appalachia. Methods We derived county-level (n = 364) data on demographic, socio-economic characteristics and dental services utilization in Appalachia from the 2010 Behavioral Risk Factor Surveillance System (BRFSS) using person-level data. We obtained county-level dental workforce availability and physician-to-population ratio estimates from Area Health Resource File, and linked them to the county-level BRFSS data. The dependent variable was the proportion using dental services within the last year in each county (ranging from 16.6% to 91.0%). We described the association between dental workforce availability and dental services utilization using ordinary least squares regression and spatial regression techniques. Spatial analyses consisted of bivariate Local Indicators of Spatial Association (LISA) and geographically weighted regression (GWR). Results Bivariate LISA showed that counties in the central and southern Appalachian regions had significant (p < .05) low-low spatial clusters (low dental workforce availability, low percent dental services utilization). GWR revealed considerable local variations in the association between dental utilization and dental workforce availability. In the multivariate GWR models, 8.5% (t-statistics >1.96) and 13.45% (t-statistics >1.96) of counties showed positive and statistically significant relationships between the dental services utilization and workforce availability of dentists and dental hygienists, respectively. Conclusions Dental workforce availability was associated with dental services utilization in the Appalachian region; however, this association was not statistically significant in all counties. The findings suggest that program and policy efforts to improve dental services utilization need to focus on factors other than increasing the dental workforce availability for many counties in Appalachia. PMID:27957773

Statistics Refresher for Molecular Imaging Technologists, Part 2: Accuracy of Interpretation, Significance, and Variance.

PubMed

Farrell, Mary Beth

2018-06-01

This article is the second part of a continuing education series reviewing basic statistics that nuclear medicine and molecular imaging technologists should understand. In this article, the statistics for evaluating interpretation accuracy, significance, and variance are discussed. Throughout the article, actual statistics are pulled from the published literature. We begin by explaining 2 methods for quantifying interpretive accuracy: interreader and intrareader reliability. Agreement among readers can be expressed simply as a percentage. However, the Cohen κ-statistic is a more robust measure of agreement that accounts for chance. The higher the κ-statistic is, the higher is the agreement between readers. When 3 or more readers are being compared, the Fleiss κ-statistic is used. Significance testing determines whether the difference between 2 conditions or interventions is meaningful. Statistical significance is usually expressed using a number called a probability ( P ) value. Calculation of P value is beyond the scope of this review. However, knowing how to interpret P values is important for understanding the scientific literature. Generally, a P value of less than 0.05 is considered significant and indicates that the results of the experiment are due to more than just chance. Variance, standard deviation (SD), confidence interval, and standard error (SE) explain the dispersion of data around a mean of a sample drawn from a population. SD is commonly reported in the literature. A small SD indicates that there is not much variation in the sample data. Many biologic measurements fall into what is referred to as a normal distribution taking the shape of a bell curve. In a normal distribution, 68% of the data will fall within 1 SD, 95% will fall within 2 SDs, and 99.7% will fall within 3 SDs. Confidence interval defines the range of possible values within which the population parameter is likely to lie and gives an idea of the precision of the statistic being measured. A wide confidence interval indicates that if the experiment were repeated multiple times on other samples, the measured statistic would lie within a wide range of possibilities. The confidence interval relies on the SE. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

Measuring and improving the quality of postoperative epidural analgesia for major abdominal surgery using statistical process control charts.

PubMed

Duncan, Fiona; Haigh, Carol

2013-10-01

To explore and improve the quality of continuous epidural analgesia for pain relief using Statistical Process Control tools. Measuring the quality of pain management interventions is complex. Intermittent audits do not accurately capture the results of quality improvement initiatives. The failure rate for one intervention, epidural analgesia, is approximately 30% in everyday practice, so it is an important area for improvement. Continuous measurement and analysis are required to understand the multiple factors involved in providing effective pain relief. Process control and quality improvement Routine prospectively acquired data collection started in 2006. Patients were asked about their pain and side effects of treatment. Statistical Process Control methods were applied for continuous data analysis. A multidisciplinary group worked together to identify reasons for variation in the data and instigated ideas for improvement. The key measure for improvement was a reduction in the percentage of patients with an epidural in severe pain. The baseline control charts illustrated the recorded variation in the rate of several processes and outcomes for 293 surgical patients. The mean visual analogue pain score (VNRS) was four. There was no special cause variation when data were stratified by surgeons, clinical area or patients who had experienced pain before surgery. Fifty-seven per cent of patients were hypotensive on the first day after surgery. We were able to demonstrate a significant improvement in the failure rate of epidurals as the project continued with quality improvement interventions. Statistical Process Control is a useful tool for measuring and improving the quality of pain management. The applications of Statistical Process Control methods offer the potential to learn more about the process of change and outcomes in an Acute Pain Service both locally and nationally. We have been able to develop measures for improvement and benchmarking in routine care that has led to the establishment of a national pain registry. © 2013 Blackwell Publishing Ltd.

Comparisons of lung tumour mortality risk in the Japanese A-bomb survivors and in the Colorado Plateau uranium miners: support for the ICRP lung model.

PubMed

Little, M P

2002-03-01

To estimate the ratio of risks for exposure to radon progeny relative to low-LET radiation based on human lung cancer data, taking account of possible time and age variations in radiation-induced lung cancer risk. Fitting two sorts of time- and age-adjusted relative risk models to a case-control dataset nested within the Colorado Plateau uranium miner cohort and to the Japanese atomic (A)-bomb survivor mortality data. If all A-bomb survivors are compared with the Colorado data, there are statistically significant (two-sided p < 0.05) differences between the two datasets in the pattern of the variation of relative risk with time after exposure, age at exposure and attained age. The excess relative risk decreases much faster with time, age at exposure and attained age in the Colorado uranium miners than in the Japanese A-bomb survivors. If only male A-bomb survivors are compared with the Colorado data, there are no longer statistically significant differences between the two datasets in the pattern of variation of relative risk with time after exposure, age at exposure or attained age. There are no statistically significant differences between the male and female A-bomb survivors in the speed of reduction of relative risk with time after exposure, age at exposure or attained age, although there are indications of rather faster reduction of relative risk with time and age among male survivors than among female survivors. The implicit risk conversion factor for exposure to radon progeny relative to the A-bomb radiation in the male survivors is 1.8 x 10(-2) Sv WLM(-1) (95% CI 6.1 x10(-3), 1.1 x 10(-1)) using a model with exponential adjustments for the effects of radiation for time since exposure and age at exposure, and 1.9 x 10(-2) Sv WLM(-1) (95% CI 6.2 x 10(-3), 1.6 x 10(-1)) using a model with adjustments for the effects of radiation proportional to powers of time since exposure and attained age. Estimates of the risk conversion factor calculated using variant assumptions as to the definition of lung cancer in the Colorado data, or by excluding miners for whom exposure estimates may be less reliable, are very similar. The absence of information on cigarette smoking in the Japanese A-bomb survivors, and the possibility that this may confound the time trends in radiation-induced lung cancer risk in that cohort, imply that these findings should be interpreted with caution. There are no statistically significant differences between the male A-bomb survivors data and the Colorado miner data in the pattern of variation of relative risk with time after exposure and age at exposure. The risk conversion factor is very close to the value suggested by the latest ICRP lung model, albeit with substantial uncertainties.

[VARIATION ON SOMATOTYPE AND WAIST CIRCUMFERENCE IN A SAMPLE OF UNIVERSITY STUDENTS BETWEEN YEARS 2012 AND 2014 IN THE TEMUCO, CHILE].

PubMed

Carrasco Alarcón, Vanessa; Martínez Salazar, Cristian; Álvarez Lepín, Cristian; Jorquera Aguilera, Carlos; Aguilar Farías, Nicolás

2015-07-01

Objetive: to determine variation on somatotype and waist circumference (WC) in university students during a three-year follow-up. a total sample of 36 first-year university students was recruited in 2012. Heath-Carter anthropometric somatotype and waist circumference were assessed in 2012 and 2014. male students showed mesomorph component (3.7-5.3-1.8) as dominant in 2012, while in 2014 endomorph and mesomorph components were equal (4.1-4.5-1.6). The somatotype in female students was dominated by endomorphic component in 2012 (5.4-4.6-1.7) and 2014 (5.3-3.2-1.6). Among somatotypes, for both, male and female students, only endomorphy showed statistically significant differences during the follow-up (p = 0,00). The endo-mesomorphic somatotype was dominant in men with 61.9% in 2012 and 38.1% in 2014. Women showed a higher percentage for meso-endomorphic somatotype with 60% in 2012 and 80% in 2014. In men, WC between 2014 and 2014 showed a statistically significant increment of 4.8% (p = 0,00). In women WC increased by 13.3% but no statistically difference was observed (p = 0,10). this study showed somatotypic change with tendency in increased endomorphy in both men and women. Despite WC values were similar to the national mean, cases with cardiometabolic risk increased during the follow-up period based on this measurement. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy

PubMed Central

Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

2011-01-01

Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction). PMID:28817030

Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy.

PubMed

Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

2011-12-23

Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction).

PyEvolve: a toolkit for statistical modelling of molecular evolution.

PubMed

Butterfield, Andrew; Vedagiri, Vivek; Lang, Edward; Lawrence, Cath; Wakefield, Matthew J; Isaev, Alexander; Huttley, Gavin A

2004-01-05

Examining the distribution of variation has proven an extremely profitable technique in the effort to identify sequences of biological significance. Most approaches in the field, however, evaluate only the conserved portions of sequences - ignoring the biological significance of sequence differences. A suite of sophisticated likelihood based statistical models from the field of molecular evolution provides the basis for extracting the information from the full distribution of sequence variation. The number of different problems to which phylogeny-based maximum likelihood calculations can be applied is extensive. Available software packages that can perform likelihood calculations suffer from a lack of flexibility and scalability, or employ error-prone approaches to model parameterisation. Here we describe the implementation of PyEvolve, a toolkit for the application of existing, and development of new, statistical methods for molecular evolution. We present the object architecture and design schema of PyEvolve, which includes an adaptable multi-level parallelisation schema. The approach for defining new methods is illustrated by implementing a novel dinucleotide model of substitution that includes a parameter for mutation of methylated CpG's, which required 8 lines of standard Python code to define. Benchmarking was performed using either a dinucleotide or codon substitution model applied to an alignment of BRCA1 sequences from 20 mammals, or a 10 species subset. Up to five-fold parallel performance gains over serial were recorded. Compared to leading alternative software, PyEvolve exhibited significantly better real world performance for parameter rich models with a large data set, reducing the time required for optimisation from approximately 10 days to approximately 6 hours. PyEvolve provides flexible functionality that can be used either for statistical modelling of molecular evolution, or the development of new methods in the field. The toolkit can be used interactively or by writing and executing scripts. The toolkit uses efficient processes for specifying the parameterisation of statistical models, and implements numerous optimisations that make highly parameter rich likelihood functions solvable within hours on multi-cpu hardware. PyEvolve can be readily adapted in response to changing computational demands and hardware configurations to maximise performance. PyEvolve is released under the GPL and can be downloaded from http://cbis.anu.edu.au/software.

Short and long periodic atmospheric variations between 25 and 200 km

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of gravity wave and planetary wave atmospheric variations are presented. Time structure of the gravity wave variations were determined by the analysis of residuals from harmonic analysis of time series data. Planetary wave contributions in the 25-85 km range were discovered and found to have significant height and latitudinal variation. Long period planetary waves, and seasonal variations were also computed by harmonic analysis. Revised height variations of the gravity wave contributions in the 25 to 85 km height range were computed. An engineering method and design values for gravity wave magnitudes and wave lengths are given to be used for such tasks as evaluating the effects on the dynamical heating, stability and control of spacecraft such as the space shuttle vehicle in launch or reentry trajectories.

[Study of the reliability in one dimensional size measurement with digital slit lamp microscope].

PubMed

Wang, Tao; Qi, Chaoxiu; Li, Qigen; Dong, Lijie; Yang, Jiezheng

2010-11-01

To study the reliability of digital slit lamp microscope as a tool for quantitative analysis in one dimensional size measurement. Three single-blinded observers acquired and repeatedly measured the images with a size of 4.00 mm and 10.00 mm on the vernier caliper, which simulatated the human eye pupil and cornea diameter under China-made digital slit lamp microscope in the objective magnification of 4 times, 10 times, 16 times, 25 times, 40 times and 4 times, 10 times, 16 times, respectively. The correctness and precision of measurement were compared. The images with 4 mm size were measured by three investigators and the average values were located between 3.98 to 4.06. For the images with 10.00 mm size, the average values fell within 10.00 ~ 10.04. Measurement results of 4.00 mm images showed, except A4, B25, C16 and C25, significant difference was noted between the measured value and the true value. Regarding measurement results of 10.00 mm iamges indicated, except A10, statistical significance was found between the measured value and the true value. In terms of comparing the results of the same size measured at different magnifications by the same investigator, except for investigators A's measurements of 10.00 mm dimension, the measurement results by all the remaining investigators presented statistical significance at different magnifications. Compared measurements of the same size with different magnifications, measurements of 4.00 mm in 4-fold magnification had no significant difference among the investigators', the remaining results were statistically significant. The coefficient of variation of all measurement results were less than 5%; as magnification increased, the coefficient of variation decreased. The measurement of digital slit lamp microscope in one-dimensional size has good reliability,and should be performed for reliability analysis before used for quantitative analysis to reduce systematic errors.

Variation characteristics and influences of climate factors on aridity index and its association with AO and ENSO in northern China from 1961 to 2012

NASA Astrophysics Data System (ADS)

Zhang, Kexin; Qian, Xiaoqing; Liu, Puxing; Xu, Yihong; Cao, Liguo; Hao, Yongpei; Dai, Shengpei

2017-10-01

Analyses of the variation characteristics for aridity index (AI) can further enhance the understanding of climate change and have effect on hydrology and agriculture. In this paper, based on the data of 283 standard meteorological stations, the temporal-spatial variations and the influences of climate factors on AI were investigated and the relationship between AI and two climate indices (the Arctic Oscillation (AO); El Nino-Southern Oscillation (ENSO)) were also assessed in northern China (NC) during the period from 1961 to 2012. The results revealed that the annual mean AI decreased at the rate of -0.031 per decade in the past 52 years and the trend was statistically significant at the 0.01 level. The Mann-Kendall (M-K) test presented that the percentages of stations with positive trends and negative trends for AI were 10 and 81.9 % (22.6 % statistically significant), respectively. Spatially, in the western part of 100° E, the extremely dry area declined and the climate tended to become wet obviously. In the eastern part of 100° E, dry area moved toward the east and the south, which resulted in the enhancement of semiarid area and the shrinkage of subhumid area. The contributions of sunshine duration and precipitation to the decline of AI are more than those of other meteorological variables in NC. Moreover, the average temperature has risen significantly and AI decreased in NC, which indicated the existence of "paradox." Relationship between climate indices (AO and ENSO) and AI demonstrated that the influence of ENSO on AI overweight the AO on AI in NC.

Concordance between local, institutional, and central pathology review in glioblastoma: implications for research and practice: a pilot study.

PubMed

Gupta, Tejpal; Nair, Vimoj; Epari, Sridhar; Pietsch, Torsten; Jalali, Rakesh

2012-01-01

There is significant inter-observer variation amongst the neuro-pathologists in the typing, subtyping, and grading of glial neoplasms for diagnosis. Centralized pathology review has been proposed to minimize this inter-observer variation and is now almost mandatory for accrual into multicentric trials. We sought to assess the concordance between neuro-pathologists on histopathological diagnosis of glioblastoma. Comparison of local, institutional, and central neuro-oncopathology reporting in a cohort of 34 patients with newly diagnosed supratentorial glioblastoma accrued consecutively at a tertiary-care institution on a prospective trial testing the addition of a new agent to standard chemo-radiation regimen. Concordance was sub-optimal between local histological diagnosis and central review, fair between local diagnosis and institutional review, and good between institutional and central review, with respect to histological typing/subtyping. Twelve (39%) of 31 patients with local histological diagnosis had identical tumor type, subtype and grade on central review. Overall agreement was modestly better (52%) between local diagnosis and institutional review. In contrast, 28 (83%) of 34 patients had completely concordant histopathologic diagnosis between institutional and central review. The inter-observer reliability test showed poor agreement between local and central review (kappa statistic=0.12, 95% confidence interval (CI): -0.03-0.32, P=0.043), but moderate agreement between institutional and central review (kappa statistic=0.51, 95%CI: 0.17-0.84, P=0.00003). Agreement between local diagnosis and institutional review was fair. There exists significant inter-observer variation regarding histopathological diagnosis of glioblastoma with significant implications for clinical research and practice. There is a need for more objective, quantitative, robust, and reproducible criteria for better subtyping for accurate diagnosis.

Responses of Solar Irradiance and the Ionosphere to an Intense Activity Region

NASA Astrophysics Data System (ADS)

Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

2018-03-01

Solar rotation (SR) variation dominates solar extremely ultraviolet (EUV) changes on the timescale of days. The F10.7 index is usually used as an indicator for solar EUV. The SR variation of F10.7 significantly enhanced during the 2008th-2009th Carrington rotations (CRs) owing to an intense active region; F10.7 increased about 180 units during that SR period. That was the most prominent SR variation of F10.7 during solar cycle 23. In this paper, global electron content (GEC) is used to investigate ionospheric response to that strong variation of solar irradiance indicated by F10.7. The variation of GEC with F10.7 was anomalous (GEC-F10.7 slope significantly decreased) during the 2008th-2009th CRs; however, GEC versus EUV variation during that period was consistent with that during adjacent time intervals when using Solar Heliospheric Observatory/Solar EUV Monitor 26-34 nm EUV measurements. The reason is that F10.7 response to that intense active region was much stronger than EUV response; thus, the EUV-F10.7 slope decreased. We confirmed decreased EUV-F10.7 slope during the 2008th-2009th CRs for different wavelengths within 27-120 nm using Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Solar EUV Experiment high spectral resolution EUV measurements. And on the basis of Solar Heliospheric Observatory/Solar EUV Monitor EUV measurements during solar cycle 23, we further presented that EUV-F10.7 slope statistically tends to decrease when the SR variation of F10.7 significantly enhances. Moreover, we found that ionospheric time lag effect to EUV is exaggerated when using F10.7, owing to the time lag effect of EUV to F10.7.

Search for the sidereal and solar diurnal modulations in the total MACRO muon data set

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Chiarusi, T.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Miller, L.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Satriano, C.; Scapparone, E.; Scholberg, K.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

2003-02-01

We have analyzed 44.3M single muons collected by MACRO from 1991 through 2000 in 2145 live days of operation. We have searched for the solar diurnal, apparent sidereal, and pseudosidereal modulation of the underground muon rate by computing hourly deviations of the muon rate from 6 month averages. We find evidence for statistically significant modulations with the solar diurnal and the sidereal periods. The amplitudes of these modulations are <0.1%, and are at the limit of the detector statistics. The pseudosidereal modulation is not statistically significant. The solar diurnal modulation is due to the daily atmospheric temperature variations at 20 km, the altitude of primary cosmic ray interactions with the atmosphere; MACRO is the deepest experiment to report this result. The sidereal modulation is in addition to the expected Compton-Getting modulation due to solar system motion relative to the local standard of rest; it represents motion of the solar system with respect to the galactic cosmic rays toward the galactic plane.

Efficacy of a radiation absorbing shield in reducing dose to the interventionalist during peripheral endovascular procedures: a single centre pilot study.

PubMed

Power, S; Mirza, M; Thakorlal, A; Ganai, B; Gavagan, L D; Given, M F; Lee, M J

2015-06-01

This prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures. A commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated. TLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142). Initial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator's body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

Eruption patterns of the chilean volcanoes Villarrica, Llaima, and Tupungatito

NASA Astrophysics Data System (ADS)

Muñoz, Miguel

1983-09-01

The historical eruption records of three Chilean volcanoes have been subjected to many statistical tests, and none have been found to differ significantly from random, or Poissonian, behaviour. The statistical analysis shows rough conformity with the descriptions determined from the eruption rate functions. It is possible that a constant eruption rate describes the activity of Villarrica; Llaima and Tupungatito present complex eruption rate patterns that appear, however, to have no statistical significance. Questions related to loading and extinction processes and to the existence of shallow secondary magma chambers to which magma is supplied from a deeper system are also addressed. The analysis and the computation of the serial correlation coefficients indicate that the three series may be regarded as stationary renewal processes. None of the test statistics indicates rejection of the Poisson hypothesis at a level less than 5%, but the coefficient of variation for the eruption series at Llaima is significantly different from the value expected for a Poisson process. Also, the estimates of the normalized spectrum of the counting process for the three series suggest a departure from the random model, but the deviations are not found to be significant at the 5% level. Kolmogorov-Smirnov and chi-squared test statistics, applied directly to ascertaining to which probability P the random Poisson model fits the data, indicate that there is significant agreement in the case of Villarrica ( P=0.59) and Tupungatito ( P=0.3). Even though the P-value for Llaima is a marginally significant 0.1 (which is equivalent to rejecting the Poisson model at the 90% confidence level), the series suggests that nonrandom features are possibly present in the eruptive activity of this volcano.

Lower incisor inclination regarding different reference planes.

PubMed

Zataráin, Brenda; Avila, Josué; Moyaho, Angeles; Carrasco, Rosendo; Velasco, Carmen

2016-09-01

The purpose of this study was to assess the degree of lower incisor inclination with respect to different reference planes. It was an observational, analytical, longitudinal, prospective study conducted on 100 lateral cephalograms which were corrected according to the photograph in natural head position in order to draw the true vertical plane (TVP). The incisor mandibular plane angle (IMPA) was compensated to eliminate the variation of the mandibular plane growth type with the formula "FMApx.- 25 (FMA) + IMPApx. = compensated IMPA (IMPACOM)". As the data followed normal distribution determined by the KolmogorovSmirnov test, parametric tests were used for the statistical analysis, Ttest, ANOVA and Pearson coefficient correlation test. Statistical analysis was performed using a statistical significance of p <0.05. There is correlation between TVP and NB line (NB) (0.8614), Frankfort mandibular incisor angle (FMIA) (0.8894), IMPA (0.6351), Apo line (Apo) (0.609), IMPACOM (0.8895) and McHorris angle (MH) (0.7769). ANOVA showed statistically significant differences between the means for the 7 variables with 95% confidence level, P=0.0001. The multiple range test showed no significant difference among means: APoNB (0.88), IMPAMH (0.36), IMPANB (0.65), FMIAIMPACOM (0.01), FMIATVP (0.18), TVPIMPACOM (0.17). There was correlation among all reference planes. There were statistically significant differences among the means of the planes measured, except for IMPACOM, FMIA and TVP. The IMPA differed significantly from the IMPACOM. The compensated IMPA and the FMIA did not differ significantly from the TVP. The true horizontal plane was mismatched with Frankfort plane in 84% of the sample with a range of 19°. The true vertical plane is adequate for measuring lower incisor inclination. Sociedad Argentina de Investigación Odontológica.

Genetic diversity in Monoporeia affinis at polluted and reference sites of the Baltic Bothnian Bay.

PubMed

Guban, Peter; Wennerström, Lovisa; Elfwing, Tina; Sundelin, Brita; Laikre, Linda

2015-04-15

The amphipod Monoporeia affinis plays an important role in the Baltic Sea ecosystem as prey and as detritivore. The species is monitored for contaminant effects, but almost nothing is known about its genetics in this region. A pilot screening for genetic variation at the mitochondrial COI gene was performed in 113 individuals collected at six sites in the northern Baltic. Three coastal sites were polluted by pulp mill effluents, PAHs, and trace metals, and two coastal reference sites were without obvious connection to pollution sources. An off-coastal reference site was also included. Contaminated sites showed lower levels of genetic diversity than the coastal reference ones although the difference was not statistically significant. Divergence patterns measured as ΦST showed no significant differentiation within reference and polluted groups, but there was significant genetic divergence between them. The off-coastal sample differed significantly from all coastal sites and also showed lower genetic variation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Toughness and strength of nanocrystalline graphene

DOE PAGES

Shekhawat, Ashivni; Ritchie, Robert O.

2016-01-28

Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects—grain boundaries and grain-boundary triple junctions—that lead to significant statistical fluctuations in toughness and strength. These fluctuations become particularly pronounced for nanocrystalline graphene where the density of defects is high. Here we use large-scale simulation and continuum modelling to show that the statistical variation in toughness and strength can be understood with ‘weakest-link’ statistics. We develop the first statistical theory of toughness in polycrystalline graphene, and elucidatemore » the nanoscale origins of the grain-size dependence of its strength and toughness. Lastly, our results should lead to more reliable graphene device design, and provide a framework to interpret experimental results in a broad class of two-dimensional materials.« less

Geophysical variables and behavior: XXI. Geomagnetic variation as possible enhancement stimuli for UFO reports preceding earthtremors.

PubMed

Persinger, M A

1985-02-01

The contribution of geomagnetic variation to the occurrence of UFORs (reports of UFOs) within the New Madrid States during the 6-mo. increments before increases in the numbers of IV-V or less intensity earthquakes within the central USA was determined. Although statistically significant zero-order correlations existed between measures of earthquakes, UFORs and geomagnetic variability, the association between the latter two deteriorated markedly when their shared variance with earthquakes was held constant. These outcomes are compatible with the hypothesis that geomagnetic variability (or phenomena associated with it) may enhance UFORs but only if tectonic stress and strain are increasing within the region.

Period variations of Algol-type eclipsing binaries AD And, TWCas and IV Cas

NASA Astrophysics Data System (ADS)

Parimucha, Štefan; Gajdoš, Pavol; Kudak, Viktor; Fedurco, Miroslav; Vaňko, Martin

2018-04-01

We present new analyses of variations in O – C diagrams of three Algol-type eclipsing binary stars: AD And, TW Cas and IV Cas. We have used all published minima times (including visual and photographic) as well as newly determined ones from our and SuperWasp observations. We determined orbital parameters of 3rd bodies in the systems with statistically significant errors, using our code based on genetic algorithms and Markov chain Monte Carlo simulations. We confirmed the multiple nature of AD And and the triple-star model of TW Cas, and we proposed a quadruple-star model of IV Cas.

Correlation between Mitochondrial Reactive Oxygen and Severity of Atherosclerosis.

PubMed

Dorighello, Gabriel G; Paim, Bruno A; Kiihl, Samara F; Ferreira, Mônica S; Catharino, Rodrigo R; Vercesi, Anibal E; Oliveira, Helena C F

2016-01-01

Atherosclerosis has been associated with mitochondria dysfunction and damage. Our group demonstrated previously that hypercholesterolemic mice present increased mitochondrial reactive oxygen (mtROS) generation in several tissues and low NADPH/NADP+ ratio. Here, we investigated whether spontaneous atherosclerosis in these mice could be modulated by treatments that replenish or spare mitochondrial NADPH, named citrate supplementation, cholesterol synthesis inhibition, or both treatments simultaneously. Robust statistical analyses in pooled group data were performed in order to explain the variation of atherosclerosis lesion areas as related to the classic atherosclerosis risk factors such as plasma lipids, obesity, and oxidative stress, including liver mtROS. Using three distinct statistical tools (univariate correlation, adjusted correlation, and multiple regression) with increasing levels of stringency, we identified a novel significant association and a model that reliably predicts the extent of atherosclerosis due to variations in mtROS. Thus, results show that atherosclerosis lesion area is positively and independently correlated with liver mtROS production rates. Based on these findings, we propose that modulation of mitochondrial redox state influences the atherosclerosis extent.

Meta-analytic approaches to determine gender differences in the age-incidence characteristics of schizophrenia and related psychoses.

PubMed

Jackson, Dan; Kirkbride, James; Croudace, Tim; Morgan, Craig; Boydell, Jane; Errazuriz, Antonia; Murray, Robin M; Jones, Peter B

2013-03-01

A recent systematic review and meta-analysis of the incidence and prevalence of schizophrenia and other psychoses in England investigated the variation in the rates of psychotic disorders. However, some of the questions of interest, and the data collected to answer these, could not be adequately addressed using established meta-analysis techniques. We developed a novel statistical method, which makes combined use of fractional polynomials and meta-regression. This was used to quantify the evidence of gender differences and a secondary peak onset in women, where the outcome of interest is the incidence of schizophrenia. Statistically significant and epidemiologically important effects were obtained using our methods. Our analysis is based on data from four studies that provide 50 incidence rates, stratified by age and gender. We describe several variations of our method, in particular those that might be used where more data is available, and provide guidance for assessing the model fit. Copyright © 2013 John Wiley & Sons, Ltd.

Increased frequencies of aberrant sperm as indicators of mutagenic damage in mice.

PubMed

Soares, E R; Sheridan, W; Haseman, J K; Segall, M

1979-02-01

We have tested the effects of TEM in 3 strains of mice using the sperm morphology assay. In addition, we have made an attempt to evaluate this test system with respect to experimental design, statistical problems and possible interlaboratory differences. Treatment with TEM results in significant increases in the percent of abnormally shaped sperm. These increases are readily detectable in sperm treated as spermatocytes and spermatogonial stages. Our data indicate possible problems associated with inter-laboratory variation in slide analysis. We have found that despite the introduction of such sources of variation, our data were consistent with respect to the effects of TEM. Another area of concern in the sperm morphology test is the presence of "outlier" animals. In our study, such animals comprised 4% of the total number of animals considered. Statistical analysis of the slides from these animals have shown that this problem can be dealt with and that when recognized as such, "outliers" do not effect the outcome of the sperm morphology assay.

Handwriting Examination: Moving from Art to Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarman, K.H.; Hanlen, R.C.; Manzolillo, P.A.

In this document, we present a method for validating the premises and methodology of forensic handwriting examination. This method is intuitively appealing because it relies on quantitative measurements currently used qualitatively by FDE's in making comparisons, and it is scientifically rigorous because it exploits the power of multivariate statistical analysis. This approach uses measures of both central tendency and variation to construct a profile for a given individual. (Central tendency and variation are important for characterizing an individual's writing and both are currently used by FDE's in comparative analyses). Once constructed, different profiles are then compared for individuality using clustermore » analysis; they are grouped so that profiles within a group cannot be differentiated from one another based on the measured characteristics, whereas profiles between groups can. The cluster analysis procedure used here exploits the power of multivariate hypothesis testing. The result is not only a profile grouping but also an indication of statistical significance of the groups generated.« less

Ozone Air Quality over North America: Part II-An Analysis of Trend Detection and Attribution Techniques.

PubMed

Porter, P Steven; Rao, S Trivikrama; Zurbenko, Igor G; Dunker, Alan M; Wolff, George T

2001-02-01

Assessment of regulatory programs aimed at improving ambient O 3 air quality is of considerable interest to the scientific community and to policymakers. Trend detection, the identification of statistically significant long-term changes, and attribution, linking change to specific clima-tological and anthropogenic forcings, are instrumental to this assessment. Detection and attribution are difficult because changes in pollutant concentrations of interest to policymakers may be much smaller than natural variations due to weather and climate. In addition, there are considerable differences in reported trends seemingly based on similar statistical methods and databases. Differences arise from the variety of techniques used to reduce nontrend variation in time series, including mitigating the effects of meteorology and the variety of metrics used to track changes. In this paper, we review the trend assessment techniques being used in the air pollution field and discuss their strengths and limitations in discerning and attributing changes in O 3 to emission control policies.

To Identify the Important Soil Properties Affecting Dinoseb Adsorption with Statistical Analysis

PubMed Central

Guan, Yiqing; Wei, Jianhui; Zhang, Danrong; Zu, Mingjuan; Zhang, Liru

2013-01-01

Investigating the influences of soil characteristic factors on dinoseb adsorption parameter with different statistical methods would be valuable to explicitly figure out the extent of these influences. The correlation coefficients and the direct, indirect effects of soil characteristic factors on dinoseb adsorption parameter were analyzed through bivariate correlation analysis, and path analysis. With stepwise regression analysis the factors which had little influence on the adsorption parameter were excluded. Results indicate that pH and CEC had moderate relationship and lower direct effect on dinoseb adsorption parameter due to the multicollinearity with other soil factors, and organic carbon and clay contents were found to be the most significant soil factors which affect the dinoseb adsorption process. A regression is thereby set up to explore the relationship between the dinoseb adsorption parameter and the two soil factors: the soil organic carbon and clay contents. A 92% of the variation of dinoseb sorption coefficient could be attributed to the variation of the soil organic carbon and clay contents. PMID:23737715

Holo-analysis.

PubMed

Rosen, G D

2006-06-01

Meta-analysis is a vague descriptor used to encompass very diverse methods of data collection analysis, ranging from simple averages to more complex statistical methods. Holo-analysis is a fully comprehensive statistical analysis of all available data and all available variables in a specified topic, with results expressed in a holistic factual empirical model. The objectives and applications of holo-analysis include software production for prediction of responses with confidence limits, translation of research conditions to praxis (field) circumstances, exposure of key missing variables, discovery of theoretically unpredictable variables and interactions, and planning future research. Holo-analyses are cited as examples of the effects on broiler feed intake and live weight gain of exogenous phytases, which account for 70% of variation in responses in terms of 20 highly significant chronological, dietary, environmental, genetic, managemental, and nutrient variables. Even better future accountancy of variation will be facilitated if and when authors of papers routinely provide key data for currently neglected variables, such as temperatures, complete feed formulations, and mortalities.

GIS-supported investigation of human EHEC and cattle VTEC O157 infections in Sweden: geographical distribution, spatial variation and possible risk factors.

PubMed Central

Kistemann, Thomas; Zimmer, Sonja; Vågsholm, Ivar; Andersson, Yvonne

2004-01-01

This article describes the spatial and temporal distribution of verotoxin-producing Escherichia coli among humans (EHEC) and cattle (VTEC) in Sweden, in order to evaluate relationships between the incidence of EHEC in humans, prevalence of VTEC O157 in livestock and agricultural structure by an ecological study. The spatial patterns of the distribution of human infections were described and compared with spatial patterns of occurrence in cattle, using a Geographic Information System (GIS). The findings implicate a concentration of human infection and cattle prevalence in the southwest of Sweden. The use of probability mapping confirmed unusual patterns of infection rates. The comparison of human and cattle infection indicated a spatial and statistical association. The correlation between variables of the agricultural structure and human EHEC incidence was high, indicating a significant statistical association of cattle and farm density with human infection. The explained variation of a multiple linear regression model was 0.56. PMID:15188718

[An evaluation of clinical characteristics and prognosis of brain-stem infarction in diabetics].

PubMed

Lu, Zheng-qi; Li, Hai-yan; Hu, Xue-qiang; Zhang, Bing-jun

2011-01-01

To analyze the relationship between diabetics and the onset, clinical outcomes and prognosis of brainstem infarction, and to evaluate the impact of diabetes on brainstem infarction. Compare 172 cases of acute brainstem infarction in patients with or without diabetes. Analyze the associated risk factors of patients with brain-stem infarction in diabetics by multi-variate logistic regression analysis. Compare the National Institutes of Health Stroke Scale (NIHSS) and Modified Rankin scale (mRS) Score, pathogenetic condition and the outcome of the two groups in different times. The systolic blood pressure (SBP), TG, LDL-C, apolipoprotein B (Apo B), glutamyl transpeptidase (γ-GT), fibrinogen (Fb), fasting blood glucose (FPG) and glycosylated hemoglobin(HbA1c)in diabetic group were higher than those in non-diabetic group, which was statistically significant (P < 0.05). From multi-variate logistic regression analysis, γ-GT, Apo B and FPG were the risk predictors of diabetes with brainstem infarction(OR = 1.017, 4.667 and 3.173, respectively), while HDL-C was protective (OR = 0.288). HbA1c was a risk predictor of severity for acute brainstem infarction (OR = 1.299), while Apo A was beneficial (OR = 0.212). Compared with brain-stem infarction in non-diabetic group, NIHSS score and intensive care therapy of diabetic groups on the admission had no statistically significance, while the NIHSS score on discharge and the outcome at 6 months' of follow-up were statistically significant. Diabetes is closely associated with brainstem infarction. Brainstem infarction with diabetes cause more rapid progression, poorer prognosis, higher rates of mortality as well as disability and higher recurrence rate of cerebral infarction.

Regional Variations in Suicide and Undetermined Death Rates among Adolescents across Canada.

PubMed

Renaud, Johanne; Lesage, Alain; Gagné, Mathieu; MacNeil, Sasha; Légaré, Gilles; Geoffroy, Marie-Claude; Skinner, Robin; McFaull, Steven

2018-04-01

Trends in rates of adolescent suicide and undetermined deaths in Canada from 1981 to 2012 were examined, focusing specifically on variations between Canadian regions. Exploratory hypotheses were formulated for regional variability in adolescent suicide rates over time in Canada. A descriptive time trend analysis using public domain vital statistics data was performed. All deaths from 1981 to 2012 among 15 to 19 year olds coded as suicides or undetermined intent according to the International Classification of Diseases, 9 th and 10 th Revisions were included. While there was an overall stability in adolescent suicide and undetermined death rates across Canada, regional analyses showed that Quebec experienced a 7.6% annual reduction between 2001 and 2012 while the Prairies and Atlantic provinces experienced significant annual increases since 2001. Ontario and British Columbia have had non-significant fluctuations since 2001. The trends remained similar overall when excluding undetermined deaths from the analyses. Variations in adolescent suicide trends across provinces were found. Factors such as provincial suicide action and prevention legislation contributing to these variations remain to be studied, but these regional differences point towards the need for better consistency of suicide prevention strategies across the country.

Regional Variations in Suicide and Undetermined Death Rates among Adolescents across Canada

PubMed Central

Lesage, Alain; Gagné, Mathieu; MacNeil, Sasha; Légaré, Gilles; Geoffroy, Marie-Claude; Skinner, Robin; McFaull, Steven

2018-01-01

Objective Trends in rates of adolescent suicide and undetermined deaths in Canada from 1981 to 2012 were examined, focusing specifically on variations between Canadian regions. Exploratory hypotheses were formulated for regional variability in adolescent suicide rates over time in Canada. Methods A descriptive time trend analysis using public domain vital statistics data was performed. All deaths from 1981 to 2012 among 15 to 19 year olds coded as suicides or undetermined intent according to the International Classification of Diseases, 9th and 10th Revisions were included. Results While there was an overall stability in adolescent suicide and undetermined death rates across Canada, regional analyses showed that Quebec experienced a 7.6% annual reduction between 2001 and 2012 while the Prairies and Atlantic provinces experienced significant annual increases since 2001. Ontario and British Columbia have had non-significant fluctuations since 2001. The trends remained similar overall when excluding undetermined deaths from the analyses. Conclusions Variations in adolescent suicide trends across provinces were found. Factors such as provincial suicide action and prevention legislation contributing to these variations remain to be studied, but these regional differences point towards the need for better consistency of suicide prevention strategies across the country. PMID:29662522

Intracyclic Velocity Variation of the Center of Mass and Hip in Breaststroke Swimming With Maximal Intensity.

PubMed

Gourgoulis, Vassilios; Koulexidis, Stylianos; Gketzenis, Panagiotis; Tzouras, Grigoris

2018-03-01

Gourgoulis, V, Koulexidis, S, Gketzenis, P, and Tzouras, G. Intra-cyclic velocity variation of the center of mass and hip in breaststroke swimming with maximal intensity. J Strength Cond Res 32(3): 830-840, 2018-The aim of the study was to compare the center of mass (CM) and hip (HIP) intracyclic velocity variation in breaststroke swimming using 3-dimensional kinematic analysis. Nine male breaststrokes, of moderate performance level, swam 25-m breaststroke with maximal intensity, and their movements were recorded, both under and above the water surface, using 8 digital cameras. Their CM and HIP velocities and their intracyclic variations were estimated after manual digitization of 28 selected points on the body in a complete arm and leg breaststroke cycle. Paired sample t-tests or Wilcoxon tests, when the assumption of normality was broken, were used for statistical analyses. In both, CM and HIP velocity-time curves, the results revealed a similar pattern of 2 clear peaks associated with the leg and arm propulsive phases and 2 minimal velocities that corresponded to the arm and leg recovery phase and the lag time between the leg and arm propulsive phases, respectively. However, despite this similar general pattern, the HIP minimum resultant velocity was significantly lower, whereas its maximal value was significantly greater, than the corresponding CM values. Consequently, the HIP intracyclic swimming velocity fluctuation significantly overestimates the actual variation of the swimmer's velocity in breaststroke swimming.

A Quantitative Analysis of the Effects of Human Activities and Climate Change on Rainfall-Runoff in Xiaoqing River Basin

NASA Astrophysics Data System (ADS)

Yang, Y.; Cao, S.; Liu, C.; Liu, Y.

2017-12-01

It is a hot topic to study the effects of human activities on the rainfall-runoff relationship and quantitatively analyze the influencing factors. According to the flexibility of Copula function to capture multivariate interdependent structure, the Copula structure between rainfall and runoff was analyzed by using the rainfall-runoff variation test method based on Archimedean Copula function to diagnose the variation of rainfall-runoff relationship. The correlation of rainfall-runoff relationship could be directly analyzed by Copula function, which could intuitively display the change of runoff in the same rainfall before and after the mutation period. The statistical method was used to simulate the underlying surface conditions before the abrupt point, and the effects of climate change and human activities on runoff changes were calculated. It can finally figure out the effects of human activities on the rainfall-runoff relationship. Taking xiaoqing river for example, the results showed that the rainfall-runoff relationship in the Xiaoqing River Basin variated in 1996 mainly due to the continuous increase of water consumption in the watershed and the change of the runoff attenuation caused by the large-scale water conservancy projects. And interannual or annual change of rainfall was not obvious; compared with the year before the variation , the runoff capacity of the basin was weakened under the same rainfall conditions after the variation ; Rainfall and runoff distribution were significantly changed and the same magnitude of rainfall and probability of runoff change were significantly different in different periods; The statistical method was used to simulate the runoff from 1996 to 2016. Compared with that from 1960 to 1995, the result showed that the contribution rate of human activities to runoff reduction was 46.8% and that of climate change was 53.2%. By relevant reference, rainfall-runoff correlation and analysis of human activities, the result was verified to be reasonable. The study can be applied to other watersheds, or used to diagnose the variation of the relationship between meteorological elements and hydrological elements so as to provide scientific basis for rational exploitation and utilization of river water resources, as well as soil and water conservation.

The temperature signature of an IMF-driven change to the global atmospheric electric circuit (GEC) in the Antarctic troposphere

NASA Astrophysics Data System (ADS)

Freeman, Mervyn; Lam, Mai Mai; Chisham, Gareth

2017-04-01

We use National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data to show that Antarctic surface air temperature anomalies result from differences in the daily-mean duskward component,By, of the interplanetary magnetic field (IMF). We find the anomalies have strong geographical and seasonal variations. Regional anomalies are evident poleward of 60˚ S and are of diminishing representative peak amplitude from autumn (3.2˚ C) to winter (2.4˚ C) to spring (1.6˚ C) to summer (0.9˚ C). We demonstrate that anomalies of statistically-significant amplitude are due to geostrophic wind anomalies, resulting from the same By changes, moving air across large meridional gradients in zonal mean air temperature between 60 and 80˚ S. Additionally, we find that the mean tropospheric temperature anomaly for geographical latitudes ≤ -70˚ peaks at about 0.7 K and is statistically significant at the 1 - 5% level between air pressures of 1000 and 500 hPa (i.e., ˜0.1 to 5.6 km altitude above sea level) and for time lags with respect to the IMF of up to 7 days. The signature propagates vertically between air pressure p ≥ 850 hPa (≤ 1.5 km) and p = 500 hPa (˜5.6 km). The characteristics of prompt response and vertical propagation within the troposphere have previously been seen in the correlation between the IMF and high-latitude air pressure anomalies, known as the Mansurov effect, at higher statistical significances (1%). We conclude that we have identified the temperature signature of the Mansurov effect in the Antarctic troposphere. Since these tropospheric anomalies have been associated with By-driven anomalies in the electric potential of the ionosphere, we further conclude that they are caused by IMF-induced changes to the global atmospheric electric circuit (GEC). Our results support the view that variations in the ionospheric potential act on the troposphere via the action of resulting variations in the downwards current of the GEC on tropospheric clouds.

Extra-articular manifestations of seronegative and seropositive rheumatoid arthritis.

PubMed

Sahatciu-Meka, Vjollca; Rexhepi, Sylejman; Manxhuka-Kerliu, Suzana; Rexhepi, Mjellma

2010-02-01

Although considered a "joint disease," rheumatoid arthritis is associated with the involvement of extra-articular manifestations. The aim of the study is the investigation and comparison of frequency and type of extra-articular manifestations in a well defined community based cohort of patients with seropositive and seronegative rheumatoid arthritis. Using the ACR (1987) criteria for rheumatoid arthritis, patients have been classified into the 2nd and 3rd functional class (ARA). The studied group consisted of 125 seronegative patients with titters lower than 1:64 as defined by Rose-Waaler test, whereas the control group consisted of 125 seropositive patients with titters of 1:64 or higher. All patients were between 25-60 years of age (Xb=49,96), with disease duration between 1-27 years (Xb=6,41). In order to present the findings of the study, the structure, prevalence, arithmetic mean (Xb), standard deviation (SB), variation quotient (QV%) and variation interval (Rmax-Rmin) have been used. Probability level has been expressed by p<0,01 and p<0,05. Correlation between the number of extra-articular manifestations and duration of the disease has been calculated by means of Pearson linear correlation. Higher presence of diffuse lung fibrosis, central and peripheral nervous system damages have been confirmed in the seropositive group, and osteoporosis in the seronegative; however, no statistical difference has been found. In extra-articular manifestations, "rheumatoid core" in the seropositive subset (chi2=4,80, p<0,05) presented significant statistical difference. Rheumatoid nodules were more frequent in seropositive subset (12%:16%), in both sexes; however, they were not of significant statistical difference. Neuropathy and lung diseases were also frequently present in seropositive group, but no statistical difference has been found regarding the statistical difference. Longer duration of the disease resulted in an increase of the number of extra-articular manifestations. Calculated linear correlation by Pearson, resulted as positive and high correlation in total (r=0,36, p<0,01), and for groups [(r=0,52, p<0,01) seronegative, (r=0,25, p<0,01) seropositive], nevertheless no significant statistical difference was found regarding the sero-status. In conclusion, extra-articular manifestations are more frequent in the seropositive patients. The longer the duration of the disease the larger the number of extra-articular manifestations. Differences with regard to sero-status and sex, with some exceptions, are not observed.

Spatial-temporal analysis of building surface temperatures in Hung Hom

NASA Astrophysics Data System (ADS)

Zeng, Ying; Shen, Yueqian

2015-12-01

This thesis presents a study on spatial-temporal analysis of building surface temperatures in Hung Hom. Observations were collected from Aug 2013 to Oct 2013 at a 30-min interval, using iButton sensors (N=20) covering twelve locations in Hung Hom. And thermal images were captured in PolyU from 05 Aug 2013 to 06 Aug 2013. A linear regression model of iButton and thermal records is established to calibrate temperature data. A 3D modeling system is developed based on Visual Studio 2010 development platform, using ArcEngine10.0 component, Microsoft Access 2010 database and C# programming language. The system realizes processing data, spatial analysis, compound query and 3D face temperature rendering and so on. After statistical analyses, building face azimuths are found to have a statistically significant relationship with sun azimuths at peak time. And seasonal building temperature changing also corresponds to the sun angle and sun azimuth variations. Building materials are found to have a significant effect on building surface temperatures. Buildings with lower albedo materials tend to have higher temperatures and larger thermal conductivity material have significant diurnal variations. For the geographical locations, the peripheral faces of campus have higher temperatures than the inner faces during day time and buildings located at the southeast are cooler than the western. Furthermore, human activity is found to have a strong relationship with building surface temperatures through weekday and weekend comparison.

No association between month of birth and biliary atresia in a country with tropical climate.

PubMed

Tanpowpong, Pornthep; Lertudomphonwanit, Chatmanee; Phuapradit, Pornpimol; Treepongkaruna, Suporn

2018-06-04

Children with biliary atresia (BA) born in countries with temperate climate showed month-of-birth (MoB) predilection during cooler months. To date, no study on the MoB-BA association has been performed in a tropical country. Our aim was to define MoB variation in children with BA in a tropical country. We studied 150 children diagnosed with BA between January 1996 and April 2015 at a teaching hospital. MoB was defined by two categories based on the precipitation: rain and dry, and three categories based on the air temperature: high, average and low. We applied the country's population data on the number of births in each period as the expected proportions of birth. A slightly higher proportion of BA children was born in the rainy months (52.7%); however, the difference was not significant compared to the general population's birth (P = 0.87). For the MoB based on the air temperature, no statistically significant difference was noted. Males with BA seemed to have a greater MoB variation compared to females, but this did not reach statistical significance. We could not find an association between MoB and BA in a tropical country. Multinational studies may aid in understanding the MoB-BA association in the tropical countries. © 2018 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).

Corneal endothelial cell density and morphology in Phramongkutklao Hospital

PubMed Central

Sopapornamorn, Narumon; Lekskul, Manapon; Panichkul, Suthee

2008-01-01

Objective To describe the corneal endothelial density and morphology in patients of Phramongkutklao Hospital and the relationship between endothelial cell parameters and other factors. Methods Four hundred and four eyes of 202 volunteers were included. Noncontact specular microscopy was performed after taking a history and testing the visual acuity, intraocular pressure measurement, Schirmer’s test and routine eye examination by slit lamp microscope. The studied parameters included mean endothelial cell density (MCD), coefficient of variation (CV), and percentage of hexagonality. Results The mean age of volunteers was 45.73 years; the range being 20 to 80 years old. Their MCD (SD), mean percentage of CV (SD) and mean (SD) percentage of hexagonality were 2623.49(325) cell/mm2, 39.43(8.23)% and 51.50(10.99)%, respectively. Statistically, MCD decreased significantly with age (p < 0.01). There was a significant difference in the percentage of CV between genders. There was no statistical significance between parameters and other factors. Conclusion The normative data of the corneal endothelium of Thai eyes indicated that, statistically, MCD decreased significantly with age. Previous studies have reported no difference in MCD, percentage of CV, and percentage of hexagonality between gender. Nevertheless, significantly different percentages of CV between genders were presented in this study. PMID:19668398

Analysis of host genetic diversity and viral entry as sources of between-host variation in viral load

USGS Publications Warehouse

Wargo, Andrew R.; Kell, Alison M.; Scott, Robert J.; Thorgaard, Gary H.; Kurath, Gael

2012-01-01

Little is known about the factors that drive the high levels of between-host variation in pathogen burden that are frequently observed in viral infections. Here, two factors thought to impact viral load variability, host genetic diversity and stochastic processes linked with viral entry into the host, were examined. This work was conducted with the aquatic vertebrate virus, Infectious hematopoietic necrosis virus (IHNV), in its natural host, rainbow trout. It was found that in controlled in vivo infections of IHNV, a suggestive trend of reduced between-fish viral load variation was observed in a clonal population of isogenic trout compared to a genetically diverse population of out-bred trout. However, this trend was not statistically significant for any of the four viral genotypes examined, and high levels of fish-to-fish variation persisted even in the isogenic trout population. A decrease in fish-to-fish viral load variation was also observed in virus injection challenges that bypassed the host entry step, compared to fish exposed to the virus through the natural water-borne immersion route of infection. This trend was significant for three of the four virus genotypes examined and suggests host entry may play a role in viral load variability. However, high levels of viral load variation also remained in the injection challenges. Together, these results indicate that although host genetic diversity and viral entry may play some role in between-fish viral load variation, they are not major factors. Other biological and non-biological parameters that may influence viral load variation are discussed.

Modeling kinetic rate variation in third generation DNA sequencing data to detect putative modifications to DNA bases

PubMed Central

Schadt, Eric E.; Banerjee, Onureena; Fang, Gang; Feng, Zhixing; Wong, Wing H.; Zhang, Xuegong; Kislyuk, Andrey; Clark, Tyson A.; Luong, Khai; Keren-Paz, Alona; Chess, Andrew; Kumar, Vipin; Chen-Plotkin, Alice; Sondheimer, Neal; Korlach, Jonas; Kasarskis, Andrew

2013-01-01

Current generation DNA sequencing instruments are moving closer to seamlessly sequencing genomes of entire populations as a routine part of scientific investigation. However, while significant inroads have been made identifying small nucleotide variation and structural variations in DNA that impact phenotypes of interest, progress has not been as dramatic regarding epigenetic changes and base-level damage to DNA, largely due to technological limitations in assaying all known and unknown types of modifications at genome scale. Recently, single-molecule real time (SMRT) sequencing has been reported to identify kinetic variation (KV) events that have been demonstrated to reflect epigenetic changes of every known type, providing a path forward for detecting base modifications as a routine part of sequencing. However, to date no statistical framework has been proposed to enhance the power to detect these events while also controlling for false-positive events. By modeling enzyme kinetics in the neighborhood of an arbitrary location in a genomic region of interest as a conditional random field, we provide a statistical framework for incorporating kinetic information at a test position of interest as well as at neighboring sites that help enhance the power to detect KV events. The performance of this and related models is explored, with the best-performing model applied to plasmid DNA isolated from Escherichia coli and mitochondrial DNA isolated from human brain tissue. We highlight widespread kinetic variation events, some of which strongly associate with known modification events, while others represent putative chemically modified sites of unknown types. PMID:23093720

Modeling kinetic rate variation in third generation DNA sequencing data to detect putative modifications to DNA bases.

PubMed

Schadt, Eric E; Banerjee, Onureena; Fang, Gang; Feng, Zhixing; Wong, Wing H; Zhang, Xuegong; Kislyuk, Andrey; Clark, Tyson A; Luong, Khai; Keren-Paz, Alona; Chess, Andrew; Kumar, Vipin; Chen-Plotkin, Alice; Sondheimer, Neal; Korlach, Jonas; Kasarskis, Andrew

2013-01-01

Current generation DNA sequencing instruments are moving closer to seamlessly sequencing genomes of entire populations as a routine part of scientific investigation. However, while significant inroads have been made identifying small nucleotide variation and structural variations in DNA that impact phenotypes of interest, progress has not been as dramatic regarding epigenetic changes and base-level damage to DNA, largely due to technological limitations in assaying all known and unknown types of modifications at genome scale. Recently, single-molecule real time (SMRT) sequencing has been reported to identify kinetic variation (KV) events that have been demonstrated to reflect epigenetic changes of every known type, providing a path forward for detecting base modifications as a routine part of sequencing. However, to date no statistical framework has been proposed to enhance the power to detect these events while also controlling for false-positive events. By modeling enzyme kinetics in the neighborhood of an arbitrary location in a genomic region of interest as a conditional random field, we provide a statistical framework for incorporating kinetic information at a test position of interest as well as at neighboring sites that help enhance the power to detect KV events. The performance of this and related models is explored, with the best-performing model applied to plasmid DNA isolated from Escherichia coli and mitochondrial DNA isolated from human brain tissue. We highlight widespread kinetic variation events, some of which strongly associate with known modification events, while others represent putative chemically modified sites of unknown types.

Morphological assessment of the stylohyoid complex variations with cone beam computed tomography in a Turkish population.

PubMed

Buyuk, C; Gunduz, K; Avsever, H

2018-01-01

The aim of this investigation was to evaluate the length, thickness, sagittal and transverse angulations and the morphological variations of the stylohyoid complex (SHC), to assess their probable associations with age and gender, and to investigate the prevalence of it in a wide range of a Turkish sub-population by using cone beam computed tomography (CBCT). The CBCT images of the 1000 patients were evaluated retrospectively. The length, thickness, sagittal and transverse angulations, morphological variations and ossification degrees of SHC were evaluated on multiplanar reconstructions (MPR) adnd three-dimensional (3D) volume rendering (3DVR) images. The data were analysed statistically by using nonparametric tests, Pearson's correlation coefficient, Student's t test, c2 test and one-way ANOVA. Statistical significance was considered at p < 0.05. It was determined that 684 (34.2%) of all 2000 SHCs were elongated (> 35 mm). The mean sagittal angle value was measured to be 72.24° and the mean transverse angle value was 70.81°. Scalariform shape, elongated type and nodular calcification pattern have the highest mean age values between the morphological groups, respectively. Calcified outline was the most prevalent calcification pattern in males. There was no correlation between length and the calcification pattern groups while scalariform shape and pseudoarticular type were the longest variations. We observed that as the anterior sagittal angle gets wider, SHC tends to get longer. The most observed morphological variations were linear shape, elongated type and calcified outline pattern. Detailed studies on the classification will contribute to the literature. (Folia Morphol 2018; 77, 1: 79-89).

ENSO related variability in the Southern Hemisphere, 1948-2000

NASA Astrophysics Data System (ADS)

Ribera, Pedro; Mann, Michael E.

2003-01-01

The spatiotemporal evolution of Southern Hemisphere climate variability is diagnosed based on the use of the NCEP reanalysis (1948-2000) dataset. Using the MTM-SVD analysis method, significant narrowband variability is isolated from the multi-variate dataset. It is found that the ENSO signal exhibits statistically significant behavior at quasiquadrennial (3-6 yr) timescales for the full time-period. A significant quasibiennial (2-3 yr) timescales emerges only for the latter half of period. Analyses of the spatial evolution of the two reconstructed signals shed additional light on linkages between low and high-latitude Southern Hemisphere climate anomalies.

The Achilles Tendon in Healthy Subjects: An Anthropometric and Ultrasound Mapping Study.

PubMed

Patel, Nick N; Labib, Sameh A

Ultrasonography is an inexpensive, fast, and reliable imaging technique widely used to assess the Achilles tendon. Although significant data exists regarding pathologic tendon changes, ultrasound data from healthy individuals are more limited. We aimed to better characterize ultrasound Achilles tendon measurements in healthy individuals and identify important correlating factors. The information collected included patient demographics, body habitus, activity level, foot dominance, and resting ankle angle. Ultrasound analysis was performed bilaterally on the Achilles tendons of 50 subjects using a high-frequency transducer to measure tendon width, thickness, cross-sectional area, and length. Males had a significantly larger mean tendon length, width, thickness, and cross-sectional area. No statistically significant difference was found in any tendon dimension between the white and black participants. Similarly, no difference was found in any tendon parameter when comparing right versus left leg dominance. Healthy subjects had a mean ankle resting angle of 45.1° ± 24° with no statistically significant difference between right and left ankles. Considering all individuals, each tendon parameter (tendon length, width, thickness, and cross-sectional area) correlated positively with subject height, weight, tibia length, and foot size. Only the Achilles cross-sectional area correlated significantly with the activity level. The resting angle of the ankle correlated positively with both tendon length and thickness. In conclusion, we found significant variations in Achilles tendon anatomy in the healthy adult population. We have thoroughly characterized significant correlations between healthy tendon dimensions and various body habitus, activity levels, and ankle parameters. Greater knowledge of the normal Achilles tendon anatomy and characterization of its variations in the healthy population will potentially allow for better pathologic diagnosis and surgical repair. Copyright © 2017 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Effects of 12-week supervised treadmill training on spatio-temporal gait parameters in patients with claudication.

PubMed

Konik, Anita; Kuklewicz, Stanisław; Rosłoniec, Ewelina; Zając, Marcin; Spannbauer, Anna; Nowobilski, Roman; Mika, Piotr

2016-01-01

The purpose of the study was to evaluate selected temporal and spatial gait parameters in patients with intermittent claudication after completion of 12-week supervised treadmill walking training. The study included 36 patients (26 males and 10 females) aged: mean 64 (SD 7.7) with intermittent claudication. All patients were tested on treadmill (Gait Trainer, Biodex). Before the programme and after its completion, the following gait biomechanical parameters were tested: step length (cm), step cycle (cycle/s), leg support time (%), coefficient of step variation (%) as well as pain-free walking time (PFWT) and maximal walking time (MWT) were measured. Training was conducted in accordance with the current TASC II guidelines. After 12 weeks of training, patients showed significant change in gait biomechanics consisting in decreased frequency of step cycle (p < 0.05) and extended step length (p < 0.05). PFWT increased by 96% (p < 0.05). MWT increased by 100% (p < 0.05). After completing the training, patients' gait was more regular, which was expressed via statistically significant decrease of coefficient of variation (p < 0.05) for both legs. No statistically significant relation between the post-training improvement of PFWT and MWT and step length increase and decreased frequency of step cycle was observed (p > 0.05). Twelve-week treadmill walking training programme may lead to significant improvement of temporal and spatial gait parameters in patients with intermittent claudication. Twelve-week treadmill walking training programme may lead to significant improvement of pain-free walking time and maximum walking time in patients with intermittent claudication.

Trends and homogeneity of monthly, seasonal, and annual rainfall over arid region of Rajasthan, India

NASA Astrophysics Data System (ADS)

Meena, Hari Mohan; Machiwal, Deepesh; Santra, Priyabrata; Moharana, Pratap Chandra; Singh, D. V.

2018-05-01

Knowledge of rainfall variability is important for regional-scale planning and management of water resources in agriculture. This study explores spatio-temporal variations, trends, and homogeneity in monthly, seasonal, and annual rainfall series of 62 stations located in arid region of Rajasthan, India using 55 year (1957-2011) data. Box-whisker plots indicate presence of outliers and extremes in annual rainfall, which made the distribution of annual rainfall right-skewed. Mean and coefficient of variation (CV) of rainfall reveals a high inter-annual variability (CV > 200%) in the western portion where the mean annual rainfall is very low. A general gradient of the mean monthly, seasonal, and annual rainfall is visible from northwest to southeast direction, which is orthogonal to the gradient of CV. The Sen's innovative trend test is found over-sensitive in evaluating statistical significance of the rainfall trends, while the Mann-Kendall test identifies significantly increasing rainfall trends in June and September. Rainfall in July shows prominently decreasing trends although none of them are found statistically significant. Monsoon and annual rainfall show significantly increasing trends at only four stations. The magnitude of trends indicates that the rainfall is increasing at a mean rate of 1.11, 2.85, and 2.89 mm year-1 in August, monsoon season, and annual series. The rainfall is found homogeneous over most of the area except for few stations situated in the eastern and northwest portions where significantly increasing trends are observed. Findings of this study indicate that there are few increasing trends in rainfall of this Indian arid region.

Sperm Competitive Ability in Drosophila melanogaster Associated With Variation in Male Reproductive Proteins

PubMed Central

Fiumera, Anthony C.; Dumont, Bethany L.; Clark, Andrew G.

2005-01-01

Multiple mating by females establishes the opportunity for postcopulatory sexual selection favoring males whose sperm is preferentially employed in fertilizations. Here we use natural variation in a wild population of Drosophila melanogaster to investigate the genetic basis of sperm competitive ability. Approximately 101 chromosome 2 substitution lines were scored for components of sperm competitive ability (P1′, P2′, fecundity, remating rate, and refractoriness), genotyped at 70 polymorphic markers in 10 male reproductive genes, and measured for transcript abundance of those genes. Permutation tests were applied to quantify the statistical significance of associations between genotype and phenotype. Nine significant associations were identified between polymorphisms in the male reproductive genes and sperm competitive ability and 13 were identified between genotype and transcript abundance, but no significant associations were found between transcript abundance and sperm competitive ability. Pleiotropy was evident in two genes: a polymorphism in Acp33A associated with both P1′ and P2′ and a polymorphism in CG17331 associated with both elevated P2′ and reduced refractoriness. The latter case is consistent with antagonistic pleiotropy and may serve as a mechanism maintaining genetic variation. PMID:15466425

Anatomic variation of depth-dependent mechanical properties in neonatal bovine articular cartilage.

PubMed

Silverberg, Jesse L; Dillavou, Sam; Bonassar, Lawrence; Cohen, Itai

2013-05-01

Articular cartilage has well known depth-dependent structure and has recently been shown to have similarly non-uniform depth-dependent mechanical properties. Here, we study anatomic variation of the depth-dependent shear modulus and energy dissipation rate in neonatal bovine knees. The regions we specifically focus on are the patellofemoral groove, trochlea, femoral condyle, and tibial plateau. In every sample, we find a highly compliant region within the first 500 µm of tissue measured from the articular surface, where the local shear modulus is reduced by up to two orders of magnitude. Comparing measurements taken from different anatomic sites, we find statistically significant differences localized within the first 50 µm. Histological images reveal these anatomic variations are associated with differences in collagen density and fiber organization. Copyright © 2012 Orthopaedic Research Society.

A Statistical Model of the Fluctuations in the Geomagnetic Field from Paleosecular Variation to Reversal

PubMed

Camps; Prevot

1996-08-09

The statistical characteristics of the local magnetic field of Earth during paleosecular variation, excursions, and reversals are described on the basis of a database that gathers the cleaned mean direction and average remanent intensity of 2741 lava flows that have erupted over the last 20 million years. A model consisting of a normally distributed axial dipole component plus an independent isotropic set of vectors with a Maxwellian distribution that simulates secular variation fits the range of geomagnetic fluctuations, in terms of both direction and intensity. This result suggests that the magnitude of secular variation vectors is independent of the magnitude of Earth's axial dipole moment and that the amplitude of secular variation is unchanged during reversals.

Diagnostic index of 3D osteoarthritic changes in TMJ condylar morphology

NASA Astrophysics Data System (ADS)

Gomes, Liliane R.; Gomes, Marcelo; Jung, Bryan; Paniagua, Beatriz; Ruellas, Antonio C.; Gonçalves, João. Roberto; Styner, Martin A.; Wolford, Larry; Cevidanes, Lucia

2015-03-01

The aim of this study was to investigate imaging statistical approaches for classifying 3D osteoarthritic morphological variations among 169 Temporomandibular Joint (TMJ) condyles. Cone beam Computed Tomography (CBCT) scans were acquired from 69 patients with long-term TMJ Osteoarthritis (OA) (39.1 ± 15.7 years), 15 patients at initial diagnosis of OA (44.9 ± 14.8 years) and 7 healthy controls (43 ± 12.4 years). 3D surface models of the condyles were constructed and Shape Correspondence was used to establish correspondent points on each model. The statistical framework included a multivariate analysis of covariance (MANCOVA) and Direction-Projection- Permutation (DiProPerm) for testing statistical significance of the differences between healthy control and the OA group determined by clinical and radiographic diagnoses. Unsupervised classification using hierarchical agglomerative clustering (HAC) was then conducted. Condylar morphology in OA and healthy subjects varied widely. Compared with healthy controls, OA average condyle was statistically significantly smaller in all dimensions except its anterior surface. Significant flattening of the lateral pole was noticed at initial diagnosis (p < 0.05). It was observed areas of 3.88 mm bone resorption at the superior surface and 3.10 mm bone apposition at the anterior aspect of the long-term OA average model. 1000 permutation statistics of DiProPerm supported a significant difference between the healthy control group and OA group (t = 6.7, empirical p-value = 0.001). Clinically meaningful unsupervised classification of TMJ condylar morphology determined a preliminary diagnostic index of 3D osteoarthritic changes, which may be the first step towards a more targeted diagnosis of this condition.

[Variation trend and significance of adult tonsil size and tongue position].

PubMed

Bin, X; Zhou, Y

2016-08-05

Objective: The aim of this study is to explore the changing trend and significance of adult tonsil size and tongue position by observing adults in different age groups. Method: Oropharyngeal cavities of 1 060 adults who undergoing health examination and had no history of tonsil surgery were observed. Friedman tongue position (FTP) and tonsil size (TS) were scored according to Friedman's criteria and results were statistic analyzed to evaluate their changing law and significance. Result: Mean FTP scores increased with age significantly（ P <0.01）; FTP score in male was lower than that in female（ P <0.01）. TS score significantly decreased with age（ P <0.05）.The average score of TS had no statistical significance in different gender. Although there was no statistical significance, total score of FTP show an increasing trend with age（ P >0.05）;Total scores of FTP were different between sexes（male 4.12±0.67，female 4.23±0.68， P <0.05）.BMI was not found to be statistically different when FTP scores, TS scores and total scores changed ( P >0.05); but it showed an increasing trend with age（ P <0.01）. Conclusion: Width of pharyngeal cavity in normal adults is always kept in certain stability, while it proves to be narrower in obese people. TS score and FTP score, which appear the opposite trend with age, can be thought as a major factor to keep a stable width of oral pharyngeal cavity. Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.

Spatio-temporal Patterns of Vegetation and Its Relationship with Precipitation and Temperature in the Yarlung Zangbo River Basin, China

NASA Astrophysics Data System (ADS)

LIU, X.; Xu, Z.; Peng, D.

2017-12-01

Vegetation growth plays a significant role on runoff variation at high altitude, and precipitation and temperature are both key factors affecting vegetation conditions. As one of the greatest international rivers in China, the Yarlung Zangbo River in the southern Qinghai-Tibetan Plateau was selected, and the spatio-temporal patterns of vegetation were analyzed by using NDVI (Normalized Difference Vegetation Index) during 1998 2014. The relationship between NDVI and precipitation as well as temperature was also investigated in this study. Results showed that the value of NDVI increases with the decrease of elevation and the largest value appears in the broadleaf forest cover. Almost all annual NDVI variations exhibit an increasing tendency, particularly for the broadleaf forest cover. On the viewpoint of statistics, only 29% pixels of NDVI with increasing tendency are of significance for the other cover, while for cultivated vegetation cover, around 82% pixels of NDVI were detected with significant increasing tendency. In addition, vegetation growth showed lagging response to precipitation, and the lag time is around one month. Moreover, in the region with elevation over 5000 m, negative relationship between NDVI and precipitation for alpine vegetation was found. Approximately 75% of NDVI variations are dominated by precipitation and temperature. These findings may provide a reference to investigate runoff variations and strengthen ecological protection for similar high-altitude areas in the future.

Evaluation of Three Different Processing Techniques in the Fabrication of Complete Dentures

PubMed Central

Chintalacheruvu, Vamsi Krishna; Balraj, Rajasekaran Uttukuli; Putchala, Lavanya Sireesha; Pachalla, Sreelekha

2017-01-01

Aims and Objectives: The objective of the present study is to compare the effectiveness of three different processing techniques and to find out the accuracy of processing techniques through number of occlusal interferences and increase in vertical dimension after denture processing. Materials and Methods: A cross-sectional study was conducted on a sample of 18 patients indicated for complete denture fabrication was selected for the study and they were divided into three subgroups. Three processing techniques, compression molding and injection molding using prepolymerized resin and unpolymerized resin, were used to fabricate dentures for each of the groups. After processing, laboratory-remounted dentures were evaluated for number of occlusal interferences in centric and eccentric relations and change in vertical dimension through vertical pin rise in articulator. Data were analyzed using statistical test ANOVA and SPSS software version 19.0 by IBM was used. Results: Data obtained from three groups were subjected to one-way ANOVA test. After ANOVA test, results with significant variations were subjected to post hoc test. Number of occlusal interferences with compression molding technique was reported to be more in both centric and eccentric positions as compared to the two injection molding techniques with statistical significance in centric, protrusive, right lateral nonworking, and left lateral working positions (P < 0.05). Mean vertical pin rise (0.52 mm) was reported to more in compression molding technique as compared to injection molding techniques, which is statistically significant (P < 0.001). Conclusions: Within the limitations of this study, injection molding techniques exhibited less processing errors as compared to compression molding technique with statistical significance. There was no statistically significant difference in processing errors reported within two injection molding systems. PMID:28713763

Evaluation of Three Different Processing Techniques in the Fabrication of Complete Dentures.

PubMed

Chintalacheruvu, Vamsi Krishna; Balraj, Rajasekaran Uttukuli; Putchala, Lavanya Sireesha; Pachalla, Sreelekha

2017-06-01

The objective of the present study is to compare the effectiveness of three different processing techniques and to find out the accuracy of processing techniques through number of occlusal interferences and increase in vertical dimension after denture processing. A cross-sectional study was conducted on a sample of 18 patients indicated for complete denture fabrication was selected for the study and they were divided into three subgroups. Three processing techniques, compression molding and injection molding using prepolymerized resin and unpolymerized resin, were used to fabricate dentures for each of the groups. After processing, laboratory-remounted dentures were evaluated for number of occlusal interferences in centric and eccentric relations and change in vertical dimension through vertical pin rise in articulator. Data were analyzed using statistical test ANOVA and SPSS software version 19.0 by IBM was used. Data obtained from three groups were subjected to one-way ANOVA test. After ANOVA test, results with significant variations were subjected to post hoc test. Number of occlusal interferences with compression molding technique was reported to be more in both centric and eccentric positions as compared to the two injection molding techniques with statistical significance in centric, protrusive, right lateral nonworking, and left lateral working positions ( P < 0.05). Mean vertical pin rise (0.52 mm) was reported to more in compression molding technique as compared to injection molding techniques, which is statistically significant ( P < 0.001). Within the limitations of this study, injection molding techniques exhibited less processing errors as compared to compression molding technique with statistical significance. There was no statistically significant difference in processing errors reported within two injection molding systems.

Metalloproteinases and leptin in vehicle drivers of public service with metabolic syndrome in Armenia, Quindío.

PubMed

Nieto Cárdenas, Olga Alicia

2015-11-01

To describe the relationship between metalloproteinase (MMP) 2, MMP-9, and leptin in drivers of public service vehicles with metabolic syndrome in the city of Armenia (Quindio, Colombia). Leptin was measured using Millipore ELISA kits. MMP-2 and MMP-9 were measured with ELISA kits from R&D Systems. Fifty-seven male drivers with metabolic syndrome with a mean age of 45.35years, BMI of 29.81, and an abdominal circumference of 105.75cm were identified. Blood pressure values were 126.5/82.5mmHg. Leptin, MMP-2, and MMP-9 levels were 24.6ng/mL, 28,1ng/mL, and 7.5ng/mL respectively. The relationship between leptin and waist circumference was statistically significant (P<.001). The explained variation (R(2)) in waist circumference, is explained in a 80.12% for the study variables, has a statistically significant association with BMI (P<.001), MMP-2 (P=.01), age (P=.01), SBP (P<.001) and DBP (P<.001). The R(2) of leptin, is explained in a 69.56% for the study variables, has a statistically significant association with BMI (P<.001), MMP-2 (P=.05) and triglycerides (P=.02). The R(2) of MMP-2, explained in 41.82% of the study variables and has a statistically significant association with waist circumference (P=.01), glucose (P=.01) and age (P=.03). Statistically significant associations were found between waist circumference and MMP-2; leptin and MMP-2, and MMP-2 and waist circumference and blood glucose. Copyright © 2014 SEEN. Published by Elsevier España, S.L.U. All rights reserved.

Reducing lumber thickness variation using real-time statistical process control

Treesearch

Thomas M. Young; Brian H. Bond; Jan Wiedenbeck

2002-01-01

A technology feasibility study for reducing lumber thickness variation was conducted from April 2001 until March 2002 at two sawmills located in the southern U.S. A real-time statistical process control (SPC) system was developed that featured Wonderware human machine interface technology (HMI) with distributed real-time control charts for all sawing centers and...

Average diurnal variation of summer lightning over the Florida peninsula

NASA Technical Reports Server (NTRS)

Maier, L. M.; Krider, E. P.; Maier, M. W.

1984-01-01

Data derived from a large network of electric field mills are used to determine the average diurnal variation of lightning in a Florida seacoast environment. The variation at the NASA Kennedy Space Center and the Cape Canaveral Air Force Station area is compared with standard weather observations of thunder, and the variation of all discharges in this area is compared with the statistics of cloud-to-ground flashes over most of the South Florida peninsula and offshore waters. The results show average diurnal variations that are consistent with statistics of thunder start times and the times of maximum thunder frequency, but that the actual lightning tends to stop one to two hours before the recorded thunder. The variation is also consistent with previous determinations of the times of maximum rainfall and maximum rainfall rate.

Hypothesis: discrepancy between intra- and interpopulation studies of the relationship between dietary salt and blood pressure: fact or fiction?

PubMed

Omvik, P

1984-01-01

It is a paradox that intra-population studies fail to show significant correlation between sodium excretion and blood pressure while a clear relationship exists in cross-cultural studies. Since daily variation of sodium excretion is high, the discrepancy between the two observations could be due to non-comparable data on sodium excretion. This is a discussion of the hypothesis that the finding of a significant correlation or not between sodium excretion and blood pressure depends on the statistical analysis of the data.

Evidence for solar flare directivity from the Gamma-Ray Spectrometer aboard the SMM satellite

NASA Technical Reports Server (NTRS)

Vestrand, W. T.; Forrest, D. J.; Chupp, E. L.; Rieger, E.; Share, G. H.

1986-01-01

A number of observations from the SMM Gamma-Ray Spectrometer are presented that altogether strongly indicate that the high-energy emission from flares is anisotropic. They are: (1) the fraction of events detected at energies above 300 keV near the limb is significantly higher than is expected for isotropically emitting flares; (2) there is a statistically significant center-to-limb variation in the 300-1000-keV spectra of flares; and (3) nearly all of the events detected at above 10 MeV are located near the limb.

Response of noctilucent cloud brightness to daily solar variations

NASA Astrophysics Data System (ADS)

Dalin, P.; Pertsev, N.; Perminov, V.; Dubietis, A.; Zadorozhny, A.; Zalcik, M.; McEachran, I.; McEwan, T.; Černis, K.; Grønne, J.; Taustrup, T.; Hansen, O.; Andersen, H.; Melnikov, D.; Manevich, A.; Romejko, V.; Lifatova, D.

2018-04-01

For the first time, long-term data sets of ground-based observations of noctilucent clouds (NLC) around the globe have been analyzed in order to investigate a response of NLC to solar UV irradiance variability on a day-to-day scale. NLC brightness has been considered versus variations of solar Lyman-alpha flux. We have found that day-to-day solar variability, whose effect is generally masked in the natural NLC variability, has a statistically significant effect when considering large statistics for more than ten years. Average increase in day-to-day solar Lyman-α flux results in average decrease in day-to-day NLC brightness that can be explained by robust physical mechanisms taking place in the summer mesosphere. Average time lags between variations of Lyman-α flux and NLC brightness are short (0-3 days), suggesting a dominant role of direct solar heating and of the dynamical mechanism compared to photodissociation of water vapor by solar Lyman-α flux. All found regularities are consistent between various ground-based NLC data sets collected at different locations around the globe and for various time intervals. Signatures of a 27-day periodicity seem to be present in the NLC brightness for individual summertime intervals; however, this oscillation cannot be unambiguously retrieved due to inevitable periods of tropospheric cloudiness.

Random field assessment of nanoscopic inhomogeneity of bone

PubMed Central

Dong, X. Neil; Luo, Qing; Sparkman, Daniel M.; Millwater, Harry R.; Wang, Xiaodu

2010-01-01

Bone quality is significantly correlated with the inhomogeneous distribution of material and ultrastructural properties (e.g., modulus and mineralization) of the tissue. Current techniques for quantifying inhomogeneity consist of descriptive statistics such as mean, standard deviation and coefficient of variation. However, these parameters do not describe the spatial variations of bone properties. The objective of this study was to develop a novel statistical method to characterize and quantitatively describe the spatial variation of bone properties at ultrastructural levels. To do so, a random field defined by an exponential covariance function was used to present the spatial uncertainty of elastic modulus by delineating the correlation of the modulus at different locations in bone lamellae. The correlation length, a characteristic parameter of the covariance function, was employed to estimate the fluctuation of the elastic modulus in the random field. Using this approach, two distribution maps of the elastic modulus within bone lamellae were generated using simulation and compared with those obtained experimentally by a combination of atomic force microscopy and nanoindentation techniques. The simulation-generated maps of elastic modulus were in close agreement with the experimental ones, thus validating the random field approach in defining the inhomogeneity of elastic modulus in lamellae of bone. Indeed, generation of such random fields will facilitate multi-scale modeling of bone in more pragmatic details. PMID:20817128

Host and parasite morphology influence congruence between host and parasite phylogenies.

PubMed

Sweet, Andrew D; Bush, Sarah E; Gustafsson, Daniel R; Allen, Julie M; DiBlasi, Emily; Skeen, Heather R; Weckstein, Jason D; Johnson, Kevin P

2018-03-23

Comparisons of host and parasite phylogenies often show varying degrees of phylogenetic congruence. However, few studies have rigorously explored the factors driving this variation. Multiple factors such as host or parasite morphology may govern the degree of phylogenetic congruence. An ideal analysis for understanding the factors correlated with congruence would focus on a diverse host-parasite system for increased variation and statistical power. In this study, we focused on the Brueelia-complex, a diverse and widespread group of feather lice that primarily parasitise songbirds. We generated a molecular phylogeny of the lice and compared this tree with a phylogeny of their avian hosts. We also tested for the contribution of each host-parasite association to the overall congruence. The two trees overall were significantly congruent, but the contribution of individual associations to this congruence varied. To understand this variation, we developed a novel approach to test whether host, parasite or biogeographic factors were statistically associated with patterns of congruence. Both host plumage dimorphism and parasite ecomorphology were associated with patterns of congruence, whereas host body size, other plumage traits and biogeography were not. Our results lay the framework for future studies to further elucidate how these factors influence the process of host-parasite coevolution. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Applications of cone-beam computed tomography to assess the effects of labial crown morphologies and collum angles on torque for maxillary anterior teeth.

PubMed

Kong, Wei-Dong; Ke, Jun-Yu; Hu, Xiang-Quan; Zhang, Wu; Li, Shu-Shu; Feng, Yi

2016-11-01

Currently, cone-beam computed tomography (CBCT) has been widely used because of its capacity to evaluate the anatomic structures of the maxilla, mandible, and teeth in 3 dimensions. However, articles about the use of CBCT to evaluate the relationships between the morphology of individual teeth and torque expression remain rare. In this study, we aimed to determine the influence of labial crown morphologies and collum angles on torque for maxillary anterior teeth using CBCT. A total of 206 extracted maxillary anterior teeth were selected to establish scanning models using dental wax, and they were scanned by CBCT. Three-dimensionally reconstructed images and median sagittal sections of the teeth were digitized and analyzed with AutoCAD software (Autodesk, San Rafael, Calif). The angle α, formed by the intersection of the tangent at a certain vertical height on the labial surface from the incisal edge with the crown long axis, and the collum angle, were measured. The variations in angle α at different heights from the incisal edge for the same type of tooth were statistically significantly different (P <0.001). Moreover, the variations between collum angles and 0° for any type of maxillary anterior tooth were statistically significant (P <0.01). This study suggested that there are great differences in labial crown morphologies and collum angles for maxillary anterior teeth between persons, indicating that the morphologies of these teeth do play important roles in torque variations. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Statistical shape analysis of clavicular cortical bone with applications to the development of mean and boundary shape models.

PubMed

Lu, Yuan-Chiao; Untaroiu, Costin D

2013-09-01

During car collisions, the shoulder belt exposes the occupant's clavicle to large loading conditions which often leads to a bone fracture. To better understand the geometric variability of clavicular cortical bone which may influence its injury tolerance, twenty human clavicles were evaluated using statistical shape analysis. The interior and exterior clavicular cortical bone surfaces were reconstructed from CT-scan images. Registration between one selected template and the remaining 19 clavicle models was conducted to remove translation and rotation differences. The correspondences of landmarks between the models were then established using coordinates and surface normals. Three registration methods were compared: the LM-ICP method; the global method; and the SHREC method. The LM-ICP registration method showed better performance than the global and SHREC registration methods, in terms of compactness, generalization, and specificity. The first four principal components obtained by using the LM-ICP registration method account for 61% and 67% of the overall anatomical variation for the exterior and interior cortical bone shapes, respectively. The length was found to be the most significant variation mode of the human clavicle. The mean and two boundary shape models were created using the four most significant principal components to investigate the size and shape variation of clavicular cortical bone. In the future, boundary shape models could be used to develop probabilistic finite element models which may help to better understand the variability in biomechanical responses and injuries to the clavicle. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Regional variation in rates of pediatric perforated appendicitis.

PubMed

Sarda, Samir; Short, Heather L; Hockenberry, Jason M; McCarthy, Ian; Raval, Mehul V

2017-09-01

While trends in perforated appendicitis (PA) rates have been studied, regional variability in pediatric admissions for PA remains unknown. A retrospective, cross-sectional analysis of the 2006-2012 Kids' Inpatient Database was conducted to examine variation in PA admission rates by region of the United States and insurance status. PA rates were calculated and reported as per 1000 admissions in accordance with national quality measure specifications. National PA rates per 1000 admissions for 2006, 2009, and 2012 were 313.9, 279.2, and 309.1, respectively. Similarly, all regions demonstrated a statistically significant decrease in PA rates between 2006 and 2009 (p<0.001), where the increase in rates between 2009 and 2012 was only statistically significant in the Midwest [Odds Ratio (OR) 1.07; 95% Confidence Interval (95%CI) 1.03-1.12] and West (OR 1.10; 95% CI 1.07-1.14). The Northeast consistently experienced the lowest PA rates. The odds of PA were highest among uninsured patients (OR 1.35; 95% CI 1.31-1.29). The South had the highest proportion of uninsured children, and these patients had the highest odds of perforation (OR 1.57; 95% CI 1.21-2.02). For children with appendicitis, geographic region and insurance status appear to be associated with perforation upon presentation. Understanding regional variation in pediatric PA rates may inform health policymakers in the constantly evolving insurance coverage landscape. Level III Treatment Study - Retrospective comparative study of appendicitis presentation in children by region of the country. Copyright © 2017 Elsevier Inc. All rights reserved.

Shiga toxigenic Escherichia coli incidence is related to small area variation in cattle density in a region in Ireland.

PubMed

Brehony, C; Cullinan, J; Cormican, M; Morris, D

2018-10-01

Shiga toxigenic Escherichia coli (STEC) are pathogenic E. coli that cause infectious diarrhoea. In some cases infection may be complicated by renal failure and death. The incidence of human infection with STEC in Ireland is the highest in Europe. The objective of the study was to examine the spatial incidence of human STEC infection in a region of Ireland with significantly higher rates of STEC incidence than the national average and to identify possible risk factors of STEC incidence at area level. Anonymised laboratory records (n = 379) from 2009 to 2015 were obtained from laboratories serving three counties in the West of Ireland. Data included location and sample date. Population and electoral division (ED) data were obtained from the Irish 2011 Census of Population. STEC incidence was calculated for each ED (n = 498) and used to map hotspots/coldspots using the Getis-Ord Gi* spatial statistic and significant spatial clustering using the Anselin's Local Moran's I statistic. Multivariable regression analysis was used to consider the importance of a number of potential predictors of STEC incidence. Incidence rates for the seven-year period ranged from 0 to 10.9 cases per 1000. A number of areas with significant local clustering of STEC incidence as well as variation in the spatial distribution of the two main serogroups associated with disease in the region i.e. O26 and O157 were identified. Cattle density was found to be a statistically significant predictor of STEC in the region. GIS analysis of routine data indicates that cattle density is associated STEC infection in this high incidence region. This finding points to the importance of agricultural practices for human health and the importance of a "one-health" approach to public policy in relation to agriculture, health and environment. Copyright © 2018 Elsevier B.V. All rights reserved.

Statistical genetics concepts and approaches in schizophrenia and related neuropsychiatric research.

PubMed

Schork, Nicholas J; Greenwood, Tiffany A; Braff, David L

2007-01-01

Statistical genetics is a research field that focuses on mathematical models and statistical inference methodologies that relate genetic variations (ie, naturally occurring human DNA sequence variations or "polymorphisms") to particular traits or diseases (phenotypes) usually from data collected on large samples of families or individuals. The ultimate goal of such analysis is the identification of genes and genetic variations that influence disease susceptibility. Although of extreme interest and importance, the fact that many genes and environmental factors contribute to neuropsychiatric diseases of public health importance (eg, schizophrenia, bipolar disorder, and depression) complicates relevant studies and suggests that very sophisticated mathematical and statistical modeling may be required. In addition, large-scale contemporary human DNA sequencing and related projects, such as the Human Genome Project and the International HapMap Project, as well as the development of high-throughput DNA sequencing and genotyping technologies have provided statistical geneticists with a great deal of very relevant and appropriate information and resources. Unfortunately, the use of these resources and their interpretation are not straightforward when applied to complex, multifactorial diseases such as schizophrenia. In this brief and largely nonmathematical review of the field of statistical genetics, we describe many of the main concepts, definitions, and issues that motivate contemporary research. We also provide a discussion of the most pressing contemporary problems that demand further research if progress is to be made in the identification of genes and genetic variations that predispose to complex neuropsychiatric diseases.

ParseCNV integrative copy number variation association software with quality tracking

PubMed Central

Glessner, Joseph T.; Li, Jin; Hakonarson, Hakon

2013-01-01

A number of copy number variation (CNV) calling algorithms exist; however, comprehensive software tools for CNV association studies are lacking. We describe ParseCNV, unique software that takes CNV calls and creates probe-based statistics for CNV occurrence in both case–control design and in family based studies addressing both de novo and inheritance events, which are then summarized based on CNV regions (CNVRs). CNVRs are defined in a dynamic manner to allow for a complex CNV overlap while maintaining precise association region. Using this approach, we avoid failure to converge and non-monotonic curve fitting weaknesses of programs, such as CNVtools and CNVassoc, and although Plink is easy to use, it only provides combined CNV state probe-based statistics, not state-specific CNVRs. Existing CNV association methods do not provide any quality tracking information to filter confident associations, a key issue which is fully addressed by ParseCNV. In addition, uncertainty in CNV calls underlying CNV associations is evaluated to verify significant results, including CNV overlap profiles, genomic context, number of probes supporting the CNV and single-probe intensities. When optimal quality control parameters are followed using ParseCNV, 90% of CNVs validate by polymerase chain reaction, an often problematic stage because of inadequate significant association review. ParseCNV is freely available at http://parsecnv.sourceforge.net. PMID:23293001

ParseCNV integrative copy number variation association software with quality tracking.

PubMed

Glessner, Joseph T; Li, Jin; Hakonarson, Hakon

2013-03-01

A number of copy number variation (CNV) calling algorithms exist; however, comprehensive software tools for CNV association studies are lacking. We describe ParseCNV, unique software that takes CNV calls and creates probe-based statistics for CNV occurrence in both case-control design and in family based studies addressing both de novo and inheritance events, which are then summarized based on CNV regions (CNVRs). CNVRs are defined in a dynamic manner to allow for a complex CNV overlap while maintaining precise association region. Using this approach, we avoid failure to converge and non-monotonic curve fitting weaknesses of programs, such as CNVtools and CNVassoc, and although Plink is easy to use, it only provides combined CNV state probe-based statistics, not state-specific CNVRs. Existing CNV association methods do not provide any quality tracking information to filter confident associations, a key issue which is fully addressed by ParseCNV. In addition, uncertainty in CNV calls underlying CNV associations is evaluated to verify significant results, including CNV overlap profiles, genomic context, number of probes supporting the CNV and single-probe intensities. When optimal quality control parameters are followed using ParseCNV, 90% of CNVs validate by polymerase chain reaction, an often problematic stage because of inadequate significant association review. ParseCNV is freely available at http://parsecnv.sourceforge.net.

Impaired clinical utility of sequential patient GEM blood gas measurements associated with calibration schedule.

PubMed

Cembrowski, George S; Xu, Qian; Cembrowski, Adam R; Mei, Junyi; Sadrzadeh, Hossein

2017-11-01

Within- and/or between-instrument variation may falsely indicate patient trends or obscure real trends. We employ a methodology that transforms sequential intra-patient results into estimates of biologic and analytic variation. We previously derived realistic biologic variation (s b ) of blood gas (BG) and hematology analytes. We extend this methodology to derive the imprecision of two GEM 4000 BG analyzers. A laboratory data repository provided arterial BG, electrolyte and metabolite results generated by two GEM 4000s on ICU patients in 2012-2013. We tabulated consecutive pairs of intra-patient results separated by increasing time interval between consecutive tests. The average between pair variations were regressed against time with the y-intercept representing the sum of the biologic variation and short term analytic variation: y o 2 =s b 2 +s a 2 . Using an equivalent equation for the Radiometer ABL, the imprecision of the two GEMs was calculated: s aGEM =(y oGEM 2 -y oABL 2 +s aABL 2 ) 1/2 . This analysis was performed for nearly all measurements, regardless of time as well for values obtained over two 12h mutually exclusive periods, starting either at 2am or 2pm. Regression graphs were derived from 1800 patients' blood gas results with least 10,000 data pairs grouped into 2h intervals. The calculated s aGEM exceed the directly measured s aABL with many GEM sigma ratios of biologic variation/analytic variation being close to unity. All of the afternoon s aGEM exceeded their morning counterparts with pH, pCO 2 , K and bicarbonate being statistically significant. For many analytes, the average analytical variation of tandem GEMs approximates the biologic variation, indicating impaired clinical usefulness of tandem sequential measurements. A significant component of this variation is due to increased variation of the GEMs between 2pm and 2am. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The Relationship between Particulate Pollution Levels in Australian Cities, Meteorology, and Landscape Fire Activity Detected from MODIS Hotspots

PubMed Central

Price, Owen F.; Williamson, Grant J.; Henderson, Sarah B.; Johnston, Fay; Bowman, David M. J. S.

2012-01-01

Smoke from bushfires is an emerging issue for fire managers because of increasing evidence for its public health effects. Development of forecasting models to predict future pollution levels based on the relationship between bushfire activity and current pollution levels would be a useful management tool. As a first step, we use daily thermal anomalies detected by the MODIS Active Fire Product (referred to as “hotspots”), pollution concentrations, and meteorological data for the years 2002 to 2008, to examine the statistical relationship between fire activity in the landscapes and pollution levels around Perth and Sydney, two large Australian cities. Resultant models were statistically significant, but differed in their goodness of fit and the distance at which the strength of the relationship was strongest. For Sydney, a univariate model for hotspot activity within 100 km explained 24% of variation in pollution levels, and the best model including atmospheric variables explained 56% of variation. For Perth, the best radius was 400 km, explaining only 7% of variation, while the model including atmospheric variables explained 31% of the variation. Pollution was higher when the atmosphere was more stable and in the presence of on-shore winds, whereas there was no effect of wind blowing from the fires toward the pollution monitors. Our analysis shows there is a good prospect for developing region-specific forecasting tools combining hotspot fire activity with meteorological data. PMID:23071788

A novel variational Bayes multiple locus Z-statistic for genome-wide association studies with Bayesian model averaging

PubMed Central

Logsdon, Benjamin A.; Carty, Cara L.; Reiner, Alexander P.; Dai, James Y.; Kooperberg, Charles

2012-01-01

Motivation: For many complex traits, including height, the majority of variants identified by genome-wide association studies (GWAS) have small effects, leaving a significant proportion of the heritable variation unexplained. Although many penalized multiple regression methodologies have been proposed to increase the power to detect associations for complex genetic architectures, they generally lack mechanisms for false-positive control and diagnostics for model over-fitting. Our methodology is the first penalized multiple regression approach that explicitly controls Type I error rates and provide model over-fitting diagnostics through a novel normally distributed statistic defined for every marker within the GWAS, based on results from a variational Bayes spike regression algorithm. Results: We compare the performance of our method to the lasso and single marker analysis on simulated data and demonstrate that our approach has superior performance in terms of power and Type I error control. In addition, using the Women's Health Initiative (WHI) SNP Health Association Resource (SHARe) GWAS of African-Americans, we show that our method has power to detect additional novel associations with body height. These findings replicate by reaching a stringent cutoff of marginal association in a larger cohort. Availability: An R-package, including an implementation of our variational Bayes spike regression (vBsr) algorithm, is available at http://kooperberg.fhcrc.org/soft.html. Contact: blogsdon@fhcrc.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:22563072

Subaru Telescope limits on cosmological variations in the fine-structure constant

NASA Astrophysics Data System (ADS)

Murphy, Michael T.; Cooksey, Kathy L.

2017-11-01

Previous, large samples of quasar absorption spectra have indicated some evidence for relative variations in the fine-structure constant (Δα/α) across the sky. However, they were likely affected by long-range distortions of the wavelength calibration, so it is important to establish a statistical sample of more reliable results from multiple telescopes. Here we triple the sample of Δα/α measurements from the Subaru Telescope which have been `supercalibrated' to correct for long-range distortions. A blinded analysis of the metallic ions in six intervening absorption systems in two Subaru quasar spectra provides no evidence for α variation, with a weighted mean of Δα/α = 3.0 ± 2.8stat ± 2.0sys parts per million (1σ statistical and systematic uncertainties). The main remaining systematic effects are uncertainties in the long-range distortion corrections, absorption profile models, and errors from redispersing multiple quasar exposures on to a common wavelength grid. The results also assume that terrestrial isotopic abundances prevail in the absorbers; assuming only the dominant terrestrial isotope is present significantly lowers Δα/α, though it is still consistent with zero. Given the location of the two quasars on the sky, our results do not support the evidence for spatial α variation, especially when combined with the 21 other recent measurements which were corrected for, or resistant to, long-range distortions. Our spectra and absorption profile fits are publicly available.

NOTE: Development and preliminary evaluation of a prototype audiovisual biofeedback device incorporating a patient-specific guiding waveform

NASA Astrophysics Data System (ADS)

Venkat, Raghu B.; Sawant, Amit; Suh, Yelin; George, Rohini; Keall, Paul J.

2008-06-01

The aim of this research was to investigate the effectiveness of a novel audio-visual biofeedback respiratory training tool to reduce respiratory irregularity. The audiovisual biofeedback system acquires sample respiratory waveforms of a particular patient and computes a patient-specific waveform to guide the patient's subsequent breathing. Two visual feedback models with different displays and cognitive loads were investigated: a bar model and a wave model. The audio instructions were ascending/descending musical tones played at inhale and exhale respectively to assist in maintaining the breathing period. Free-breathing, bar model and wave model training was performed on ten volunteers for 5 min for three repeat sessions. A total of 90 respiratory waveforms were acquired. It was found that the bar model was superior to free breathing with overall rms displacement variations of 0.10 and 0.16 cm, respectively, and rms period variations of 0.77 and 0.33 s, respectively. The wave model was superior to the bar model and free breathing for all volunteers, with an overall rms displacement of 0.08 cm and rms periods of 0.2 s. The reduction in the displacement and period variations for the bar model compared with free breathing was statistically significant (p = 0.005 and 0.002, respectively); the wave model was significantly better than the bar model (p = 0.006 and 0.005, respectively). Audiovisual biofeedback with a patient-specific guiding waveform significantly reduces variations in breathing. The wave model approach reduces cycle-to-cycle variations in displacement by greater than 50% and variations in period by over 70% compared with free breathing. The planned application of this device is anatomic and functional imaging procedures and radiation therapy delivery.

Genetic Differentiation among Maruca vitrata F. (Lepidoptera: Crambidae) Populations on Cultivated Cowpea and Wild Host Plants: Implications for Insect Resistance Management and Biological Control Strategies

PubMed Central

Agunbiade, Tolulope A.; Coates, Brad S.; Datinon, Benjamin; Djouaka, Rousseau; Sun, Weilin; Tamò, Manuele; Pittendrigh, Barry R.

2014-01-01

Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a polyphagous insect pest that feeds on a variety of leguminous plants in the tropics and subtropics. The contribution of host-associated genetic variation on population structure was investigated using analysis of mitochondrial cytochrome oxidase 1 (cox1) sequence and microsatellite marker data from M. vitrata collected from cultivated cowpea (Vigna unguiculata L. Walp.), and alternative host plants Pueraria phaseoloides (Roxb.) Benth. var. javanica (Benth.) Baker, Loncocarpus sericeus (Poir), and Tephrosia candida (Roxb.). Analyses of microsatellite data revealed a significant global FST estimate of 0.05 (P≤0.001). The program STRUCTURE estimated 2 genotypic clusters (co-ancestries) on the four host plants across 3 geographic locations, but little geographic variation was predicted among genotypes from different geographic locations using analysis of molecular variance (AMOVA; among group variation −0.68%) or F-statistics (F ST Loc = −0.01; P = 0.62). These results were corroborated by mitochondrial haplotype data (φSTLoc = 0.05; P = 0.92). In contrast, genotypes obtained from different host plants showed low but significant levels of genetic variation (F ST Host = 0.04; P = 0.01), which accounted for 4.08% of the total genetic variation, but was not congruent with mitochondrial haplotype analyses (φSTHost = 0.06; P = 0.27). Variation among host plants at a location and host plants among locations showed no consistent evidence for M. vitrata population subdivision. These results suggest that host plants do not significantly influence the genetic structure of M. vitrata, and this has implications for biocontrol agent releases as well as insecticide resistance management (IRM) for M. vitrata in West Africa. PMID:24647356

Variation in pediatric outpatient adenotonsillectomy costs in a multihospital network.

PubMed

Meier, Jeremy D; Zhang, Yingying; Greene, Tom H; Curtis, Jonathan L; Srivastava, Rajendu

2015-05-01

Identify hospital costs for same-day pediatric adenotonsillectomy (T&A) surgery, and evaluate surgeon, hospital, and patient factors influencing variation in costs, and compare relationship of costs to complications for T&A. Observational retrospective cohort study. A multihospital network's standardized activity-based accounting system was used to determine hospital costs per T&A from 1998 to 2012. Children 1 to 18 years old who underwent same-day T&A surgery were included. Subjects with additional procedures were excluded. Mixed effects analyses were performed to identify variation in mean costs due to surgeon, hospital, and patient factors. Surgeons' mean cost/case was related to subsequent complications, defined as any unplanned visit within 21 days in the healthcare system. The study cohort included 26,626 T&As performed by 66 surgeons at 18 hospitals. Mean cost per T&A was $1,355 ± $505. Mixed effects analysis using patient factors as fixed effects and surgeon and hospital as a random effect identified significant variation in mean costs per surgeon, with 95% of surgeons having a mean cost/case between 67% and 150% of the overall mean (range, $874-$2,232/case). Similar variability was found among hospitals, with 95% of the facilities having mean costs between 64% to 156% of the mean (range, $1,029-$2,385/case). Severity of illness and several other patient factors exhibited small but statistically significant associations with cost. Surgeons' mean cost/case was moderately associated with an increased complication rate. Significant variation in same-day pediatric T&A surgery costs exists among different surgeons and hospitals within a multihospital network. Reducing variation in costs while maintaining outcomes may improve healthcare value and eliminate waste. 4. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Potential environmental influences on variation in body size and sexual size dimorphism among Arizona populations of the western diamond-backed rattlesnake (Crotalus atrox)

USGS Publications Warehouse

Amarello, Melissa; Nowak, Erica M.; Taylor, Emily N.; Schuett, Gordon W.; Repp, Roger A.; Rosen, Philip C.; Hardy, David L.

2010-01-01

Differences in resource availability and quality along environmental gradients are important influences contributing to intraspecific variation in body size, which influences numerous life-history traits. Here, we examined variation in body size and sexual size dimorphism (SSD) in relation to temperature, seasonality, and precipitation among 10 populations located throughout Arizona of the western diamond-backed rattlesnake (Crotalus atrox). Specifically, in our analyses we addressed the following questions: (i) Are adult males larger in cooler, wetter areas? (ii) Does female body size respond differently to environmental variation? (iii) Is seasonality a better predictor of body size variation? (iv) Is SSD positively correlated with increased resources? We demonstrate that male and female C. atrox are larger in body size in cooler (i.e., lower average annual maximum, minimum, and mean temperature) and wetter areas (i.e., higher average annual precipitation, more variable precipitation, and available surface water). Although SSD in C. atrox appeared to be more pronounced in cooler, wetter areas, this relationship did not achieve statistical significance.

Geographic Variation in Diagnostic Ability and Quality of Care Metrics: A Case Study of Ankylosing Spondylitis and Low Back Pain

PubMed Central

Shafrin, Jason; Griffith, Jenny; Shim, Jin Joo; Huber, Caroline; Ganguli, Arijit; Aubry, Wade

2017-01-01

Studies examining geographic variation in care for low back pain often focus on process and outcome measures conditional on patient diagnosis but generally do not take into account a physician’s ability to diagnose the root cause of low back pain. In our case study, we used increased detection of ankylosing spondylitis—a relatively rare inflammatory back disease—as a proxy for diagnostic ability and measured the relationship between ankylosing spondylitis detection, potentially inappropriate low back pain care, and cost. Using 5 years of health insurance claims data, we found significant variation in ankylosing spondylitis detection across metropolitan statistical areas (MSAs), with 8.1% of the variation in detection explained by a region’s racial composition. Furthermore, low back pain patients in MSAs with higher ankylosing spondylitis detection had 7.9% lower use of corticosteroids, 9.0% lower use of opioids, and 8.2% lower pharmacy cost, compared with patients living in low-detection MSAs. PMID:28548005

Variations in the prevalence of antibody to brucella infection in cattle by farm, area and district in Kenya.

PubMed Central

Kadohira, M.; McDermott, J. J.; Shoukri, M. M.; Kyule, M. N.

1997-01-01

Variations in the sero-prevalence of antibody to brucella infection by cow, farm and area factors were investigated for three contrasting districts in Kenya: Samburu, an arid and pastoral area: Kiambu, a tropical highland area; and Kilifi, a typical tropical coastal area. Cattle were selected by a two-stage cluster sampling procedure and visited once between August 1991 and 1992. Schall's algorithm, a statistical model suitable for multi-level analysis was used. Using this model, older age, free grazing and large herd size (> or = 31) were associated with higher seroprevalence. Also, significant farm-to-farm, area-to-area and district-to-district variations were estimated. The patterns of high risk districts and areas seen were consistent with known animal husbandry and movement risk factors, but the larger than expected farm-to-farm variation within high risk areas and districts could not be explained. Thus, a multi-level method provided additional information beyond conventional analyses of sero-prevalence data. PMID:9042033

Quantitatively measured tremor in hand-arm vibration-exposed workers.

PubMed

Edlund, Maria; Burström, Lage; Hagberg, Mats; Lundström, Ronnie; Nilsson, Tohr; Sandén, Helena; Wastensson, Gunilla

2015-04-01

The aim of the present study was to investigate the possible increase in hand tremor in relation to hand-arm vibration (HAV) exposure in a cohort of exposed and unexposed workers. Participants were 178 male workers with or without exposure to HAV. The study is cross-sectional regarding the outcome of tremor and has a longitudinal design with respect to exposure. The dose of HAV exposure was collected via questionnaires and measurements at several follow-ups. The CATSYS Tremor Pen(®) was used for measuring postural tremor. Multiple linear regression methods were used to analyze associations between different tremor variables and HAV exposure, along with predictor variables with biological relevance. There were no statistically significant associations between the different tremor variables and cumulative HAV or current exposure. Age was a statistically significant predictor of variation in tremor outcomes for three of the four tremor variables, whereas nicotine use was a statistically significant predictor of either left or right hand or both hands for all four tremor variables. In the present study, there was no evidence of an exposure-response association between HAV exposure and measured postural tremor. Increase in age and nicotine use appeared to be the strongest predictors of tremor.

A lognormal distribution of the lengths of terminal twigs on self-similar branches of elm trees.

PubMed

Koyama, Kohei; Yamamoto, Ken; Ushio, Masayuki

2017-01-11

Lognormal distributions and self-similarity are characteristics associated with a wide range of biological systems. The sequential breakage model has established a link between lognormal distributions and self-similarity and has been used to explain species abundance distributions. To date, however, there has been no similar evidence in studies of multicellular organismal forms. We tested the hypotheses that the distribution of the lengths of terminal stems of Japanese elm trees (Ulmus davidiana), the end products of a self-similar branching process, approaches a lognormal distribution. We measured the length of the stem segments of three elm branches and obtained the following results: (i) each occurrence of branching caused variations or errors in the lengths of the child stems relative to their parent stems; (ii) the branches showed statistical self-similarity; the observed error distributions were similar at all scales within each branch and (iii) the multiplicative effect of these errors generated variations of the lengths of terminal twigs that were well approximated by a lognormal distribution, although some statistically significant deviations from strict lognormality were observed for one branch. Our results provide the first empirical evidence that statistical self-similarity of an organismal form generates a lognormal distribution of organ sizes. © 2017 The Author(s).

Stochastic simulation and robust design optimization of integrated photonic filters

NASA Astrophysics Data System (ADS)

Weng, Tsui-Wei; Melati, Daniele; Melloni, Andrea; Daniel, Luca

2017-01-01

Manufacturing variations are becoming an unavoidable issue in modern fabrication processes; therefore, it is crucial to be able to include stochastic uncertainties in the design phase. In this paper, integrated photonic coupled ring resonator filters are considered as an example of significant interest. The sparsity structure in photonic circuits is exploited to construct a sparse combined generalized polynomial chaos model, which is then used to analyze related statistics and perform robust design optimization. Simulation results show that the optimized circuits are more robust to fabrication process variations and achieve a reduction of 11%-35% in the mean square errors of the 3 dB bandwidth compared to unoptimized nominal designs.

Spatial statistics of hydrography and water chemistry in a eutrophic boreal lake based on sounding and water samples.

PubMed

Leppäranta, Matti; Lewis, John E; Heini, Anniina; Arvola, Lauri

2018-06-04

Spatial variability, an essential characteristic of lake ecosystems, has often been neglected in field research and monitoring. In this study, we apply spatial statistical methods for the key physics and chemistry variables and chlorophyll a over eight sampling dates in two consecutive years in a large (area 103 km 2 ) eutrophic boreal lake in southern Finland. In the four summer sampling dates, the water body was vertically and horizontally heterogenic except with color and DOC, in the two winter ice-covered dates DO was vertically stratified, while in the two autumn dates, no significant spatial differences in any of the measured variables were found. Chlorophyll a concentration was one order of magnitude lower under the ice cover than in open water. The Moran statistic for spatial correlation was significant for chlorophyll a and NO 2 +NO 3 -N in all summer situations and for dissolved oxygen and pH in three cases. In summer, the mass centers of the chemicals were within 1.5 km from the geometric center of the lake, and the 2nd moment radius ranged in 3.7-4.1 km respective to 3.9 km for the homogeneous situation. The lateral length scales of the studied variables were 1.5-2.5 km, about 1 km longer in the surface layer. The detected spatial "noise" strongly suggests that besides vertical variation also the horizontal variation in eutrophic lakes, in particular, should be considered when the ecosystems are monitored.

Memory and Trend of Precipitation in China during 1966-2013

NASA Astrophysics Data System (ADS)

Du, M.; Sun, F.; Liu, W.

2017-12-01

As climate change has had a significant impact on water cycle, the characteristic and variation of precipitation under climate change turned into a hotspot in hydrology. This study aims to analyze the trend and memory (both short-term and long-term) of precipitation in China. To do that, we apply statistical tests (including Mann-Kendall test, Ljung-Box test and Hurst exponent) to annual precipitation (P), frequency of rainy day (λ) and mean daily rainfall in days when precipitation occurs (α) in China (1966-2013). We also use a resampling approach to determine the field significance. From there, we evaluate the spatial distribution and percentages of stations with significant memory or trend. We find that the percentages of significant downtrends for λ and significant uptrends for α are significantly larger than the critical values at 95% field significance level, probably caused by the global warming. From these results, we conclude that extra care is necessary when significant results are obtained using statistical tests. This is because the null hypothesis could be rejected by chance and this situation is more likely to occur if spatial correlation is ignored according to the results of the resampling approach.

Temporal distribution of alcohol related facial fractures.

PubMed

Lee, Kai H; Qiu, Michael; Sun, Jiandong

2017-11-01

This study aimed to address 2 important aspects of temporal pattern in alcohol-related facial fractures: (1) comparison of temporal pattern of alcohol-related facial fracture (alcohol group) presentation with non-alcohol-related fracture (non-alcohol group) presentation; (2) temporal pattern of patient demographic characteristics, injury characteristics, and surgical management in the alcohol group presentation. This study retrospectively examined the Victorian admitted episodes data set (VAED) for the years 2010 to 2013. VAED is a standardized set of data collected during all hospital presentations in Victoria. The study found higher incidence of alcohol-related facial fracture presentations during weekends and during the summer and spring months compared with non-alcohol-related fractures (statistically significant). Alcohol-related facial fractures are more likely to involve male patients in the 20- to 29-year age group, occur as a result of interpersonal violence, and require shorter hospital stays during weekend admissions (statistically significant). No statistically significant relationship has been observed in seasonal variation across all variables. This study found distinct characteristics in temporal distribution of alcohol-related facial fractures. These characteristics are, in particular, significant in weekend trauma admissions. Such information is important in workforce planning, resource distribution, and implementation of injury prevention programs. Copyright © 2017 Elsevier Inc. All rights reserved.

Fibroblast growth factor 20 (FGF20) polymorphism is a risk factor for Parkinson's disease in Chinese population.

PubMed

Pan, Jing; Li, Hui; Wang, Ying; Ma, Jian-Fang; Zhang, Jin; Wang, Gang; Liu, Jun; Wang, Xi-Jin; Xiao, Qin; Chen, Sheng-Di

2012-06-01

The etiology of Parkinson's disease (PD) is not well established. Genetic variation in fibroblast growth factor 20 (FGF20) might influence the risk of PD occurrence and development. In this study, Two DNA polymorphisms at genetic variation in FGF20, rs2720208 (C/T) and rs1721100 (C/G), were genotyped by direct sequencing in Han Chinese population, including 394 PD patients and 383 healthy controls. Statistical analyses revealed that for rs1721100 (C/G) polymorphism, there were significant differences in genotype distribution between PD and healthy-matched controls. For rs12720208 (C/T) polymorphism, there was no significant difference in genotype distribution and gender and age-related differences between PD and control group. Results in this study revealed that the rs1721100(C/G) polymorphism is a risk factor for PD in Han Chinese population, while rs12720208(C/T) polymorphism is not significantly associated with PD. Copyright © 2012 Elsevier Ltd. All rights reserved.

Geographic variation in forest composition and precipitation predict the synchrony of forest insect outbreaks

Treesearch

Kyle J. Haynes; Andrew M. Liebhold; Ottar N. Bjørnstad; Andrew J. Allstadt; Randall S. Morin

2018-01-01

Evaluating the causes of spatial synchrony in population dynamics in nature is notoriously difficult due to a lack of data and appropriate statistical methods. Here, we use a recently developed method, a multivariate extension of the local indicators of spatial autocorrelation statistic, to map geographic variation in the synchrony of gypsy moth outbreaks. Regression...

Variation in reaction norms: Statistical considerations and biological interpretation.

PubMed

Morrissey, Michael B; Liefting, Maartje

2016-09-01

Analysis of reaction norms, the functions by which the phenotype produced by a given genotype depends on the environment, is critical to studying many aspects of phenotypic evolution. Different techniques are available for quantifying different aspects of reaction norm variation. We examine what biological inferences can be drawn from some of the more readily applicable analyses for studying reaction norms. We adopt a strongly biologically motivated view, but draw on statistical theory to highlight strengths and drawbacks of different techniques. In particular, consideration of some formal statistical theory leads to revision of some recently, and forcefully, advocated opinions on reaction norm analysis. We clarify what simple analysis of the slope between mean phenotype in two environments can tell us about reaction norms, explore the conditions under which polynomial regression can provide robust inferences about reaction norm shape, and explore how different existing approaches may be used to draw inferences about variation in reaction norm shape. We show how mixed model-based approaches can provide more robust inferences than more commonly used multistep statistical approaches, and derive new metrics of the relative importance of variation in reaction norm intercepts, slopes, and curvatures. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Application of HF Doppler measurements for the investigation of internal atmospheric waves in the ionosphere

NASA Astrophysics Data System (ADS)

Petrova, I. R.; Bochkarev, V. V.; Latipov, R. R.

2009-09-01

We present results of the spectral analysis of data series of Doppler frequency shifted signals reflected from the ionosphere, using experimental data received at Kazan University, Russia. Spectra of variations with periods from 1 min to 60 days have been calculated and analyzed for different scales of periods. The power spectral density for spring and winter differs by a factor of 3-4. Local maxima of variation amplitude are detected, which are statistically significant. The periods of these amplitude increases range from 6 to 12 min for winter, and from 24 to 48 min for autumn. Properties of spectra for variations with the periods of 1-72 h have been analyzed. The maximum of variation intensity for all seasons and frequencies corresponds to the period of 24 h. Spectra of variations with periods from 3 to 60 days have been calculated. The maxima periods of power spectral density have been detected by the MUSIC method for the high spectral resolution. The detected periods correspond to planetary wave periods. Analysis of spectra for days with different level of geomagnetic activity shows that the intensity of variations for days with a high level of geomagnetic activity is higher.

Discrete-element modeling of nacre-like materials: Effects of random microstructures on strain localization and mechanical performance

NASA Astrophysics Data System (ADS)

Abid, Najmul; Mirkhalaf, Mohammad; Barthelat, Francois

2018-03-01

Natural materials such as nacre, collagen, and spider silk are composed of staggered stiff and strong inclusions in a softer matrix. This type of hybrid microstructure results in remarkable combinations of stiffness, strength, and toughness and it now inspires novel classes of high-performance composites. However, the analytical and numerical approaches used to predict and optimize the mechanics of staggered composites often neglect statistical variations and inhomogeneities, which may have significant impacts on modulus, strength, and toughness. Here we present an analysis of localization using small representative volume elements (RVEs) and large scale statistical volume elements (SVEs) based on the discrete element method (DEM). DEM is an efficient numerical method which enabled the evaluation of more than 10,000 microstructures in this study, each including about 5,000 inclusions. The models explore the combined effects of statistics, inclusion arrangement, and interface properties. We find that statistical variations have a negative effect on all properties, in particular on the ductility and energy absorption because randomness precipitates the localization of deformations. However, the results also show that the negative effects of random microstructures can be offset by interfaces with large strain at failure accompanied by strain hardening. More specifically, this quantitative study reveals an optimal range of interface properties where the interfaces are the most effective at delaying localization. These findings show how carefully designed interfaces in bioinspired staggered composites can offset the negative effects of microstructural randomness, which is inherent to most current fabrication methods.

Restoration of MRI data for intensity non-uniformities using local high order intensity statistics

PubMed Central

Hadjidemetriou, Stathis; Studholme, Colin; Mueller, Susanne; Weiner, Michael; Schuff, Norbert

2008-01-01

MRI at high magnetic fields (>3.0 T) is complicated by strong inhomogeneous radio-frequency fields, sometimes termed the “bias field”. These lead to non-biological intensity non-uniformities across the image. They can complicate further image analysis such as registration and tissue segmentation. Existing methods for intensity uniformity restoration have been optimized for 1.5 T, but they are less effective for 3.0 T MRI, and not at all satisfactory for higher fields. Also, many of the existing restoration algorithms require a brain template or use a prior atlas, which can restrict their practicalities. In this study an effective intensity uniformity restoration algorithm has been developed based on non-parametric statistics of high order local intensity co-occurrences. These statistics are restored with a non-stationary Wiener filter. The algorithm also assumes a smooth non-uniformity and is stable. It does not require a prior atlas and is robust to variations in anatomy. In geriatric brain imaging it is robust to variations such as enlarged ventricles and low contrast to noise ratio. The co-occurrence statistics improve robustness to whole head images with pronounced non-uniformities present in high field acquisitions. Its significantly improved performance and lower time requirements have been demonstrated by comparing it to the very commonly used N3 algorithm on BrainWeb MR simulator images as well as on real 4 T human head images. PMID:18621568

[Empirical study on non-point sources pollution based on landscape pattern & ecological processes theory: a case of soil water loss on the Loess Plateau in China].

PubMed

Suo, An-ning; Wang, Tian-ming; Wang, Hui; Yu, Bo; Ge, Jian-ping

2006-12-01

Non-point sources pollution is one of main pollution modes which pollutes the earth surface environment. Aimed at soil water loss (a typical non-point sources pollution problem) on the Losses Plateau in China, the paper applied a landscape patternevaluation method to twelve watersheds of Jinghe River Basin on the Loess Plateau by means of location-weighted landscape contrast index(LCI) and landscape slope index(LSI). The result showed that LSI of farm land, low density grass land, forest land and LCI responded significantly to soil erosion modulus and responded to depth of runoff, while the relationship between these landscape index and runoff variation index and erosion variation index were not statistically significant. This tell us LSI and LWLCI are good indicators of soil water loss and thus have big potential in non-point source pollution risk evaluation.

Speckle reduction in optical coherence tomography by adaptive total variation method

NASA Astrophysics Data System (ADS)

Wu, Tong; Shi, Yaoyao; Liu, Youwen; He, Chongjun

2015-12-01

An adaptive total variation method based on the combination of speckle statistics and total variation restoration is proposed and developed for reducing speckle noise in optical coherence tomography (OCT) images. The statistical distribution of the speckle noise in OCT image is investigated and measured. With the measured parameters such as the mean value and variance of the speckle noise, the OCT image is restored by the adaptive total variation restoration method. The adaptive total variation restoration algorithm was applied to the OCT images of a volunteer's hand skin, which showed effective speckle noise reduction and image quality improvement. For image quality comparison, the commonly used median filtering method was also applied to the same images to reduce the speckle noise. The measured results demonstrate the superior performance of the adaptive total variation restoration method in terms of image signal-to-noise ratio, equivalent number of looks, contrast-to-noise ratio, and mean square error.

Investigating output and energy variations and their relationship to delivery QA results using Statistical Process Control for helical tomotherapy.

PubMed

Binny, Diana; Mezzenga, Emilio; Lancaster, Craig M; Trapp, Jamie V; Kairn, Tanya; Crowe, Scott B

2017-06-01

The aims of this study were to investigate machine beam parameters using the TomoTherapy quality assurance (TQA) tool, establish a correlation to patient delivery quality assurance results and to evaluate the relationship between energy variations detected using different TQA modules. TQA daily measurement results from two treatment machines for periods of up to 4years were acquired. Analyses of beam quality, helical and static output variations were made. Variations from planned dose were also analysed using Statistical Process Control (SPC) technique and their relationship to output trends were studied. Energy variations appeared to be one of the contributing factors to delivery output dose seen in the analysis. Ion chamber measurements were reliable indicators of energy and output variations and were linear with patient dose verifications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Soil carbon inventories under a bioenergy crop (switchgrass): Measurement limitations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garten, C.T. Jr.; Wullschleger, S.D.

Approximately 5 yr after planting, coarse root carbon (C) and soil organic C (SOC) inventories were compared under different types of plant cover at four switchgrass (Panicum virgatum L.) production field trials in the southeastern USA. There was significantly more coarse root C under switchgrass (Alamo variety) and forest cover than tall fescue (Festuca arundinacea Schreb.), corn (Zea mays L.), or native pastures of mixed grasses. Inventories of SOC under switchgrass were not significantly greater than SOC inventories under other plant covers. At some locations the statistical power associated with ANOVA of SOC inventories was low, which raised questions aboutmore » whether differences in SOC could be detected statistically. A minimum detectable difference (MDD) for SOC inventories was calculated. The MDD is the smallest detectable difference between treatment means once the variation, significance level, statistical power, and sample size are specified. The analysis indicated that a difference of {approx}50 mg SOC/cm{sup 2} or 5 Mg SOC/ha, which is {approx}10 to 15% of existing SOC, could be detected with reasonable sample sizes and good statistical power. The smallest difference in SOC inventories that can be detected, and only with exceedingly large sample sizes, is {approx}2 to 3%. These measurement limitations have implications for monitoring and verification of proposals to ameliorate increasing global atmospheric CO{sub 2} concentrations by sequestering C in soils.« less

Refining the Use of Linkage Disequilibrium as a Robust Signature of Selective Sweeps.

PubMed

Jacobs, Guy S; Sluckin, Tim J; Kivisild, Toomas

2016-08-01

During a selective sweep, characteristic patterns of linkage disequilibrium can arise in the genomic region surrounding a selected locus. These have been used to infer past selective sweeps. However, the recombination rate is known to vary substantially along the genome for many species. We here investigate the effectiveness of current (Kelly's [Formula: see text] and [Formula: see text]) and novel statistics at inferring hard selective sweeps based on linkage disequilibrium distortions under different conditions, including a human-realistic demographic model and recombination rate variation. When the recombination rate is constant, Kelly's [Formula: see text] offers high power, but is outperformed by a novel statistic that we test, which we call [Formula: see text] We also find this statistic to be effective at detecting sweeps from standing variation. When recombination rate fluctuations are included, there is a considerable reduction in power for all linkage disequilibrium-based statistics. However, this can largely be reversed by appropriately controlling for expected linkage disequilibrium using a genetic map. To further test these different methods, we perform selection scans on well-characterized HapMap data, finding that all three statistics-[Formula: see text] Kelly's [Formula: see text] and [Formula: see text]-are able to replicate signals at regions previously identified as selection candidates based on population differentiation or the site frequency spectrum. While [Formula: see text] replicates most candidates when recombination map data are not available, the [Formula: see text] and [Formula: see text] statistics are more successful when recombination rate variation is controlled for. Given both this and their higher power in simulations of selective sweeps, these statistics are preferred when information on local recombination rate variation is available. Copyright © 2016 by the Genetics Society of America.

Statistical Significance of Optical Map Alignments

PubMed Central

Sarkar, Deepayan; Goldstein, Steve; Schwartz, David C.

2012-01-01

Abstract The Optical Mapping System constructs ordered restriction maps spanning entire genomes through the assembly and analysis of large datasets comprising individually analyzed genomic DNA molecules. Such restriction maps uniquely reveal mammalian genome structure and variation, but also raise computational and statistical questions beyond those that have been solved in the analysis of smaller, microbial genomes. We address the problem of how to filter maps that align poorly to a reference genome. We obtain map-specific thresholds that control errors and improve iterative assembly. We also show how an optimal self-alignment score provides an accurate approximation to the probability of alignment, which is useful in applications seeking to identify structural genomic abnormalities. PMID:22506568

Detecting measurement outliers: remeasure efficiently

NASA Astrophysics Data System (ADS)

Ullrich, Albrecht

2010-09-01

Shrinking structures, advanced optical proximity correction (OPC) and complex measurement strategies continually challenge critical dimension (CD) metrology tools and recipe creation processes. One important quality ensuring task is the control of measurement outlier behavior. Outliers could trigger false positive alarm for specification violations impacting cycle time or potentially yield. Constant high level of outliers not only deteriorates cycle time but also puts unnecessary stress on tool operators leading eventually to human errors. At tool level the sources of outliers are natural variations (e.g. beam current etc.), drifts, contrast conditions, focus determination or pattern recognition issues, etc. Some of these can result from suboptimal or even wrong recipe settings, like focus position or measurement box size. Such outliers, created by an automatic recipe creation process faced with more complicated structures, would manifest itself rather as systematic variation of measurements than the one caused by 'pure' tool variation. I analyzed several statistical methods to detect outliers. These range from classical outlier tests for extrema, robust metrics like interquartile range (IQR) to methods evaluating the distribution of different populations of measurement sites, like the Cochran test. The latter suits especially the detection of systematic effects. The next level of outlier detection entwines additional information about the mask and the manufacturing process with the measurement results. The methods were reviewed for measured variations assumed to be normally distributed with zero mean but also for the presence of a statistically significant spatial process signature. I arrive at the conclusion that intelligent outlier detection can influence the efficiency and cycle time of CD metrology greatly. In combination with process information like target, typical platform variation and signature, one can tailor the detection to the needs of the photomask at hand. By monitoring the outlier behavior carefully, weaknesses of the automatic recipe creation process can be spotted.

Using active shape modeling based on MRI to study morphologic and pitch-related functional changes affecting vocal structures and the airway.

PubMed

Miller, Nicola A; Gregory, Jennifer S; Aspden, Richard M; Stollery, Peter J; Gilbert, Fiona J

2014-09-01

The shape of the vocal tract and associated structures (eg, tongue and velum) is complicated and varies according to development and function. This variability challenges interpretation of voice experiments. Quantifying differences between shapes and understanding how vocal structures move in relation to each other is difficult using traditional linear and angle measurements. With statistical shape models, shape can be characterized in terms of independent modes of variation. Here, we build an active shape model (ASM) to assess morphologic and pitch-related functional changes affecting vocal structures and the airway. Using a cross-sectional study design, we obtained six midsagittal magnetic resonance images from 10 healthy adults (five men and five women) at rest, while breathing out, and while listening to, and humming low and high notes. Eighty landmark points were chosen to define the shape of interest and an ASM was built using these (60) images. Principal component analysis was used to identify independent modes of variation, and statistical analysis was performed using one-way repeated-measures analysis of variance. Twenty modes of variation were identified with modes 1 and 2 accounting for half the total variance. Modes 1 and 9 were significantly associated with humming low and high notes (P < 0.001) and showed coordinated changes affecting the cervical spine, vocal structures, and airway. Mode 2 highlighted wide structural variations between subjects. This study highlights the potential of active shape modeling to advance understanding of factors underlying morphologic and pitch-related functional variations affecting vocal structures and the airway in health and disease. Copyright © 2014 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Long-Term Changes in the Extreme Significant Wave Heights on the Western North Pacific: Impacts of Tropical Cyclone Activity and ENSO

NASA Astrophysics Data System (ADS)

Yang, Sinil; Oh, Jaiho

2018-02-01

Seasonal extreme wave statistics were reproduced by using the 25-km-grid global wave model of WAVEWATCH-III. The results showed that the simulated wave dataset for the present climate (1979-2009) was similar to Climate Forecast System Reanalysis (CFSR) wave data. Statistics such as the root mean squared error (RMSE) and correlation coefficient (CC) over the western North Pacific (WNP) basin were 0.5 m and 0.69 over the analysis domain. The largest trends and standard deviation were around the southern coast of Japan and western edge of the WNP. Linear regression analysis was employed to identify the relationship between the leading principal components (PCs) of significant wave heights (SWHs) in the peak season of July to September and sea surface temperature (SST) anomalies in the equatorial Pacific. The results indicated that the inter-annual variability of SWH can be associated with the El Niño-Southern Oscillation in the peak season. The CC between the first PC of the SWH and anomalies in the Nino 3.4 SST index was also significant at a 99% confidence level. Significant variations in the SWH are affected by tropical cyclones (TCs) caused by increased SST anomalies. The genesis and development of simulated TCs can be important to the variation in SWHs for the WNP in the peak season. Therefore, we can project the variability of SWHs through TC activity based on changes in SST conditions for the equatorial Pacific in the future.

A Candidate Gene Association Study of Bone Mineral Density in an Iranian Population.

PubMed

Dastgheib, Seyed Alireza; Gartland, Alison; Tabei, Seyed Mohammad Bagher; Omrani, Gholamhossein Ranjbar; Teare, Marion Dawn

2016-01-01

The genetic epidemiology of variation in bone mineral density (BMD) and osteoporosis is not well studied in Iranian populations and needs more research. We report a candidate gene association study of BMD variation in a healthy cross-sectional study of 501 males and females sampled from the Iranian Multi-Centre Osteoporosis Study, Shiraz, Iran. We selected to study the association with 21 single nucleotide polymorphisms (SNPs) located in the 7 candidate genes LRP5, RANK, RANKL, OPG, P2RX7, VDR , and ESR1 . BMD was measured at the three sites L2-L4, neck of femur, and total hip. Association between BMD and each SNP was assessed using multiple linear regression assuming an allele dose (additive effect) on BMD (adjusted for age and sex). Statistically significant (at the unadjusted 5% level) associations were seen with seven SNPs in five of the candidate genes. Two SNPs showed statistically significant association with more than one BMD site. Significant association was seen between BMD at all the three sites with the VDR SNP rs731246 (L2-L4 p  = 0.038; neck of femur p  = 0.001; and total hip p  < 0.001). The T allele was consistently associated with lower BMD than the C allele. Significant association was also seen for the P2RX7 SNP rs3751143, where the G allele was consistently associated with lower BMD than the T allele (L2-L4 p  = 0.069; neck of femur p  = 0.024; and total hip p  = 0.045).

Quantifying variation in speciation and extinction rates with clade data.

PubMed

Paradis, Emmanuel; Tedesco, Pablo A; Hugueny, Bernard

2013-12-01

High-level phylogenies are very common in evolutionary analyses, although they are often treated as incomplete data. Here, we provide statistical tools to analyze what we name "clade data," which are the ages of clades together with their numbers of species. We develop a general approach for the statistical modeling of variation in speciation and extinction rates, including temporal variation, unknown variation, and linear and nonlinear modeling. We show how this approach can be generalized to a wide range of situations, including testing the effects of life-history traits and environmental variables on diversification rates. We report the results of an extensive simulation study to assess the performance of some statistical tests presented here as well as of the estimators of speciation and extinction rates. These latter results suggest the possibility to estimate correctly extinction rate in the absence of fossils. An example with data on fish is presented. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Gender and Age Related Effects While Watching TV Advertisements: An EEG Study.

PubMed

Cartocci, Giulia; Cherubino, Patrizia; Rossi, Dario; Modica, Enrica; Maglione, Anton Giulio; di Flumeri, Gianluca; Babiloni, Fabio

2016-01-01

The aim of the present paper is to show how the variation of the EEG frontal cortical asymmetry is related to the general appreciation perceived during the observation of TV advertisements, in particular considering the influence of the gender and age on it. In particular, we investigated the influence of the gender on the perception of a car advertisement (Experiment 1) and the influence of the factor age on a chewing gum commercial (Experiment 2). Experiment 1 results showed statistically significant higher approach values for the men group throughout the commercial. Results from Experiment 2 showed significant lower values by older adults for the spot, containing scenes not very enjoyed by them. In both studies, there was no statistical significant difference in the scene relative to the product offering between the experimental populations, suggesting the absence in our study of a bias towards the specific product in the evaluated populations. These evidences state the importance of the creativity in advertising, in order to attract the target population.

Gender and Age Related Effects While Watching TV Advertisements: An EEG Study

PubMed Central

Cartocci, Giulia; Cherubino, Patrizia; Rossi, Dario; Modica, Enrica; Maglione, Anton Giulio; di Flumeri, Gianluca; Babiloni, Fabio

2016-01-01

The aim of the present paper is to show how the variation of the EEG frontal cortical asymmetry is related to the general appreciation perceived during the observation of TV advertisements, in particular considering the influence of the gender and age on it. In particular, we investigated the influence of the gender on the perception of a car advertisement (Experiment 1) and the influence of the factor age on a chewing gum commercial (Experiment 2). Experiment 1 results showed statistically significant higher approach values for the men group throughout the commercial. Results from Experiment 2 showed significant lower values by older adults for the spot, containing scenes not very enjoyed by them. In both studies, there was no statistical significant difference in the scene relative to the product offering between the experimental populations, suggesting the absence in our study of a bias towards the specific product in the evaluated populations. These evidences state the importance of the creativity in advertising, in order to attract the target population. PMID:27313602

Evaluation of psychiatric and genetic risk factors among primary relatives of suicide completers in Delhi NCR region, India.

PubMed

Pasi, Shivani; Singh, Piyoosh Kumar; Pandey, Rajeev Kumar; Dikshit, P C; Jiloha, R C; Rao, V R

2015-10-30

Suicide as a public health problem is studied worldwide and association of psychiatric and genetic risk factors for suicidal behavior are the point of discussion in studies across different ethnic groups. The present study is aimed at evaluating psychiatric and genetic traits among primary relatives of suicide completer families in an urban Indian population. Bi-variate analysis shows significant increase in major depression (PHQ and Hamilton), stress, panic disorder, somatoform disorder and suicide attemptamong primary compared to other relatives. Sib pair correlations also reveal significant results for major depression (Hamilton), stress, suicide attempt, intensity of suicide ideation and other anxiety syndrome. 5-HTTLPR, 5-HTT (Stin2) and COMT risk alleles are higher among primary relatives, though statistically insignificant. Backward conditional logistic regression analysis show only independent variable, Depression (Hamilton) made a unique statistically significant contribution to the model in primary relatives. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Analysis of corneal endothelial cell density and morphology after laser in situ keratomileusis using two types of femtosecond lasers

PubMed Central

Tomita, Minoru; Waring, George O; Watabe, Miyuki

2012-01-01

Purpose To compare two different femtosecond lasers used for flap creation during laser-assisted in situ keratomileusis (LASIK) surgery in terms of their effects on the corneal endothelium. Methods We performed LASIK surgery on 254 eyes of 131 patients using IntraLase FS60 (Abbott Medical Optics, Inc, Irvine, CA; IntraLase group) and 254 eyes of 136 patients using Femto LDV (Ziemer Group AG, Port, Switzerland; LDV group) for corneal flap creation. The mean cell density, coefficient of variation, and hexagonality of the corneal endothelial cells were determined and the results were statistically compared. Results There were no statistically significant differences in the corneal morphology between pre and post LASIK results in each group, nor were there significant differences between the results of both groups at 3 months post LASIK. Conclusions Both IntraLase FS60 and Ziemer Femto LDV are able to create flaps without significant adverse effects on the corneal endothelial morphology through 3 months after LASIK surgery. PMID:23055680

Copy number variation and microdeletions of the Y chromosome linked genes and loci across different categories of Indian infertile males.

PubMed

Kumari, Anju; Yadav, Sandeep Kumar; Misro, Man Mohan; Ahmad, Jamal; Ali, Sher

2015-12-07

We analyzed 34 azoospermic (AZ), 43 oligospermic (OS), and 40 infertile males with normal spermiogram (INS) together with 55 normal fertile males (NFM) from the Indian population. AZ showed more microdeletions in the AZFa and AZFb regions whereas oligospermic ones showed more microdeletions in the AZFc region. Frequency of the AZF partial deletions was higher in males with spermatogenic impairments than in INS. Significantly, SRY, DAZ and BPY2 genes showed copy number variation across different categories of the patients and much reduced copies of the DYZ1 repeat arrays compared to that in normal fertile males. Likewise, INS showed microdeletions, sequence and copy number variation of several Y linked genes and loci. In the context of infertility, STS deletions and copy number variations both were statistically significant (p = 0.001). Thus, semen samples used during in vitro fertilization (IVF) and assisted reproductive technology (ART) must be assessed for the microdeletions of AZFa, b and c regions in addition to the affected genes reported herein. Present study is envisaged to be useful for DNA based diagnosis of different categories of the infertile males lending support to genetic counseling to the couples aspiring to avail assisted reproductive technologies.

Evolution properties of online user preference diversity

NASA Astrophysics Data System (ADS)

Guo, Qiang; Ji, Lei; Liu, Jian-Guo; Han, Jingti

2017-02-01

Detecting the evolution properties of online user preference diversity is of significance for deeply understanding online collective behaviors. In this paper, we empirically explore the evolution patterns of online user rating preference, where the preference diversity is measured by the variation coefficient of the user rating sequence. The statistical results for four real systems show that, for movies and reviews, the user rating preference would become diverse and then get centralized finally. By introducing the empirical variation coefficient, we present a Markov model, which could regenerate the evolution properties of two online systems regarding to the stable variation coefficients. In addition, we investigate the evolution of the correlation between the user ratings and the object qualities, and find that the correlation would keep increasing as the user degree increases. This work could be helpful for understanding the anchoring bias and memory effects of the online user collective behaviors.

Geography of breast cancer incidence according to age & birth cohorts.

PubMed

Gregorio, David I; Ford, Chandler; Samociuk, Holly

2017-06-01

Geographic variation in breast cancer incidence across Connecticut was examined according to age and birth cohort -specific groups. We assigned each of 60,937 incident breast cancer cases diagnosed in Connecticut, 1986-2009, to one of 828 census tracts around the state. Global and local spatial statistics estimated rate variation across the state according to age and birth cohorts. We found the global distribution of incidence rates across places to be more heterogeneous for younger women and later birth cohorts. Concurrently, the spatial scan identified more locations with significantly high rates that pertained to larger proportions of at-risk women within these groups. Geographic variation by age groups was more pronounced than by birth cohorts. Geographic patterns of cancer incidence exhibit differences within and across age and birth cohorts. With the continued insights from descriptive epidemiology, our capacity to effectively limit spatial disparities in cancer will improve. Copyright © 2017 Elsevier Ltd. All rights reserved.

Change in ozone trends at southern high latitudes

NASA Technical Reports Server (NTRS)

Yang, E.-S.; Cunnold, D. M.; Newchurch, M. J.; Salawitch, R. J.

2005-01-01

Long-term ozone variations at 60-70degS in spring are investigated using ground-based and satellite measurements. Strong positive correlation is shown between year-to-year variations of ozone and temperature in the Antarctic collar region in Septembers and Octobers. Based on this relationship, the effect of year-to-year variations in vortex dynamics has been filtered out. This process results in an ozone time series that shows increasing springtime ozone losses over the Antarctic until the mid-1990s. Since approximately 1997 the ozone losses have leveled off. The analysis confirms that this change is consistent across all instruments and is statistically significant at the 95% confidence level. This analysis quantifies the beginning of the recovery of the ozone hole, which is expected from the leveling off of stratospheric halogen loading due to the ban on CFCs and other halocarbons initiated by the Montreal Protocol.

Using basic statistics on the individual patient's own numeric data.

PubMed

Hart, John

2012-12-01

This theoretical report gives an example for how coefficient of variation (CV) and quartile analysis (QA) to assess outliers might be able to be used to analyze numeric data in practice for an individual patient. A patient was examined for 8 visits using infrared instrumentation for measurement of mastoid fossa temperature differential (MFTD) readings. The CV and QA were applied to the readings. The participant also completed the Short Form-12 health perception survey on each visit, and these findings were correlated with CV to determine if CV had outcomes support (clinical significance). An outlier MFTD reading was observed on the eighth visit according to QA that coincided with the largest CV value for the MFTDs. Correlations between the Short Form-12 and CV were low to negligible, positive, and statistically nonsignificant. This case provides an example of how basic statistical analyses could possibly be applied to numerical data in chiropractic practice for an individual patient. This might add objectivity to analyzing an individual patient's data in practice, particularly if clinical significance of a clinical numerical finding is unknown.

Empirical Bayes scan statistics for detecting clusters of disease risk variants in genetic studies.

PubMed

McCallum, Kenneth J; Ionita-Laza, Iuliana

2015-12-01

Recent developments of high-throughput genomic technologies offer an unprecedented detailed view of the genetic variation in various human populations, and promise to lead to significant progress in understanding the genetic basis of complex diseases. Despite this tremendous advance in data generation, it remains very challenging to analyze and interpret these data due to their sparse and high-dimensional nature. Here, we propose novel applications and new developments of empirical Bayes scan statistics to identify genomic regions significantly enriched with disease risk variants. We show that the proposed empirical Bayes methodology can be substantially more powerful than existing scan statistics methods especially so in the presence of many non-disease risk variants, and in situations when there is a mixture of risk and protective variants. Furthermore, the empirical Bayes approach has greater flexibility to accommodate covariates such as functional prediction scores and additional biomarkers. As proof-of-concept we apply the proposed methods to a whole-exome sequencing study for autism spectrum disorders and identify several promising candidate genes. © 2015, The International Biometric Society.

Visual classification of very fine-grained sediments: Evaluation through univariate and multivariate statistics

USGS Publications Warehouse

Hohn, M. Ed; Nuhfer, E.B.; Vinopal, R.J.; Klanderman, D.S.

1980-01-01

Classifying very fine-grained rocks through fabric elements provides information about depositional environments, but is subject to the biases of visual taxonomy. To evaluate the statistical significance of an empirical classification of very fine-grained rocks, samples from Devonian shales in four cored wells in West Virginia and Virginia were measured for 15 variables: quartz, illite, pyrite and expandable clays determined by X-ray diffraction; total sulfur, organic content, inorganic carbon, matrix density, bulk density, porosity, silt, as well as density, sonic travel time, resistivity, and ??-ray response measured from well logs. The four lithologic types comprised: (1) sharply banded shale, (2) thinly laminated shale, (3) lenticularly laminated shale, and (4) nonbanded shale. Univariate and multivariate analyses of variance showed that the lithologic classification reflects significant differences for the variables measured, difference that can be detected independently of stratigraphic effects. Little-known statistical methods found useful in this work included: the multivariate analysis of variance with more than one effect, simultaneous plotting of samples and variables on canonical variates, and the use of parametric ANOVA and MANOVA on ranked data. ?? 1980 Plenum Publishing Corporation.

Statistical evidence of seismo-ionospheric precursors of the GPS total electron content in China

NASA Astrophysics Data System (ADS)

Chen, Yuh-Ing; Huang, Chi-Shen; Liu, Jann-Yenq

2015-04-01

Evidence of the seismo-ionospheric precursor (SIP) is reported by statistically investigating the relationship between the total electron content (TEC) in global ionosphere map (GIM) and 56 M≥6.0 earthquakes during 1998-2013 in China. A median-based method together with the z test is employed to examine the TEC variations 30 days before and after the earthquake. It is found that the TEC significantly decreases 0600-1000 LT 1-6 days before the earthquake, and anomalously increases in 3 time periods of 1300-1700 LT 12-15 days; 0000-0500 LT 15-17 days; and 0500-0900 LT 22-28 days before the earthquake. The receiver operating characteristic (ROC) curve is then used to evaluate the efficiency of TEC for predicting M≥6.0 earthquakes in China during a specified time period. Statistical results suggest that the SIP is the significant TEC reduction in the morning period of 0600-1000 LT. The SIP is further confirmed since the area under the ROC curve is positively associated with the earthquake magnitude.

Statistical evidences of seismo-ionospheric precursors applying receiver operating characteristic (ROC) curve on the GPS total electron content in China

NASA Astrophysics Data System (ADS)

Chen, Yuh-Ing; Huang, Chi-Shen; Liu, Jann-Yenq

2015-12-01

Evidence of the seismo-ionospheric precursor (SIP) is reported by statistically investigating the relationship between the total electron content (TEC) in global ionosphere map (GIM) and 56 M ⩾ 6.0 earthquakes during 1998-2013 in China. A median-based method together with the z test is employed to examine the TEC variations 30 days before and after the earthquake. It is found that the TEC significantly decreases 0600-1000 LT 1-6 days before the earthquake, and anomalously increases in 3 time periods of 1300-1700 LT 12-15 days; 0000-0500 LT 15-17 days; and 0500-0900 LT 22-28 days before the earthquake. The receiver operating characteristic (ROC) curve is then used to evaluate the efficiency of TEC for predicting M ⩾ 6.0 earthquakes in China during a specified time period. Statistical results suggest that the SIP is the significant TEC reduction in the morning period of 0600-1000 LT. The SIP is further confirmed since the area under the ROC curve is positively associated with the earthquake magnitude.

Inhalation developmental toxicology studies: Teratology study of n-hexane in mice: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mast, T.J.; Decker, J.R.; Stoney, K.H.

Gestational exposure to n-hexane resulted in an increase in the number of resorbed fetuses for exposure groups relative to the control group; however, the increases were not directly correlated to exposure concentration. The differences were statistically significant for the 200-ppM with respect to total intrauterine death (early plus late resorptions), and with respect to late resorptions for the 5000-ppM group. A small, but statistically significant, reduction in female (but not male) fetal body weight relative to the control group was observed at the 5000-ppM exposure level. There were no exposure-related increases in any individual fetal malformation or variation, nor wasmore » there any increase in the incidence of combined malformations or variations. Gestational exposure of CD-1 mice to n-hexane vapors appeared to cause a degree of concentration-related developmental toxicity in the absence of overt maternal toxicity, but the test material was not found to be teratogenic. This developmental toxicity was manifested as an increase in the number of resorptions per litter for all exposure levels, and as a decrease in the uterine: extra-gestational weight gain ratio at the 5000-ppM exposure level. Because of the significant increase in the number of resorptions at the 200-ppM exposure level, a no observable effect level (NOEL) for developmental toxicity was not established for exposure of mice to 200, 1000 or 5000-ppM n-hexane vapors. 21 refs., 3 figs., 9 tabs.« less

Personality assessment and model comparison with behavioral data: A statistical framework and empirical demonstration with bonobos (Pan paniscus).

PubMed

Martin, Jordan S; Suarez, Scott A

2017-08-01

Interest in quantifying consistent among-individual variation in primate behavior, also known as personality, has grown rapidly in recent decades. Although behavioral coding is the most frequently utilized method for assessing primate personality, limitations in current statistical practice prevent researchers' from utilizing the full potential of their coding datasets. These limitations include the use of extensive data aggregation, not modeling biologically relevant sources of individual variance during repeatability estimation, not partitioning between-individual (co)variance prior to modeling personality structure, the misuse of principal component analysis, and an over-reliance upon exploratory statistical techniques to compare personality models across populations, species, and data collection methods. In this paper, we propose a statistical framework for primate personality research designed to address these limitations. Our framework synthesizes recently developed mixed-effects modeling approaches for quantifying behavioral variation with an information-theoretic model selection paradigm for confirmatory personality research. After detailing a multi-step analytic procedure for personality assessment and model comparison, we employ this framework to evaluate seven models of personality structure in zoo-housed bonobos (Pan paniscus). We find that differences between sexes, ages, zoos, time of observation, and social group composition contributed to significant behavioral variance. Independently of these factors, however, personality nonetheless accounted for a moderate to high proportion of variance in average behavior across observational periods. A personality structure derived from past rating research receives the strongest support relative to our model set. This model suggests that personality variation across the measured behavioral traits is best described by two correlated but distinct dimensions reflecting individual differences in affiliation and sociability (Agreeableness) as well as activity level, social play, and neophilia toward non-threatening stimuli (Openness). These results underscore the utility of our framework for quantifying personality in primates and facilitating greater integration between the behavioral ecological and comparative psychological approaches to personality research. © 2017 Wiley Periodicals, Inc.

Epidemiology of Mental Retardation.

ERIC Educational Resources Information Center

Heber, Rick

Prevalence data on mental retardation is presented including international estimates on general prevalence, age directions, geographical variations within the United States, racial and ethnic variations, economic class distributions, family variations, and population distribution in institutions. Statistics are also provided in areas of specific…

Genetic Variations in SLCO Transporter Genes Contributing to Racial Disparity in Aggressiveness of Prostate Cancer

DTIC Science & Technology

2017-10-01

should not be construed as an official Department of the Army position, policy or decision unless so designated by other documentation. REPORT... control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE October 2017 2. REPORT TYPE Annual 3. DATES COVERED 15 Sep 2016...statistically significant difference among these three groups in either tumor characteristics including Gleason score, stage and aggressiveness, or

Geographic variations in the cost of spine surgery.

PubMed

Goz, Vadim; Rane, Ajinkya; Abtahi, Amir M; Lawrence, Brandon D; Brodke, Darrel S; Spiker, William Ryan

2015-09-01

Retrospective review. To define the geographic variation in costs of anterior cervical discectomy and fusion (ACDF) and posterolateral fusion (PLF). ACDF and lumbar PLF are common procedures that are used in the treatment of spinal pathologies. To optimize value, both the benefits and costs of an intervention must be quantified. Data on costs are scarce in comparison with data on total charges. This study aims at defining the costs of ACDF and PLF and describing the geographic variation within the United States. Medicare Provider Utilization and Payment data were used to investigate the costs associated with ACDF, PLF, and total knee arthroplasty (TKA). Average total costs of the procedures were compared by state and geographic region. Combined professional and facility costs for a single-level ACDF had a national mean of $13,899. Total costs for a single-level PLF had a mean of $25,858. Total costs for a primary TKA had a national mean of $13,039. The cost increased to an average of $22,138 for TKA with major comorbidities. Analysis of geographic trends showed statistically significant differences in total costs of PLF, TKA, and TKA, with major complications or comorbidities between geographic regions (P < 0.01 for all). Three of the 4 procedures (PLF, TKA, and TKA with major complications or comorbidities) showed statistically significant variation in cost between geographic regions. The Midwest provided the lowest cost for all procedures. Similar geographic trends in the cost of spinal fusions and TKAs suggest that these trends may not be limited to spine-related procedures. Surgical costs were found to correlate with cost of living but were not associated with the population of the state. These data shed light on the actual cost of common surgical procedures throughout the United States and will allow further progress toward the development of cost-effective, value-driven care. 3.

Measurements of experimental precision for trials with cowpea (Vigna unguiculata L. Walp.) genotypes.

PubMed

Teodoro, P E; Torres, F E; Santos, A D; Corrêa, A M; Nascimento, M; Barroso, L M A; Ceccon, G

2016-05-09

The aim of this study was to evaluate the suitability of statistics as experimental precision degree measures for trials with cowpea (Vigna unguiculata L. Walp.) genotypes. Cowpea genotype yields were evaluated in 29 trials conducted in Brazil between 2005 and 2012. The genotypes were evaluated with a randomized block design with four replications. Ten statistics that were estimated for each trial were compared using descriptive statistics, Pearson correlations, and path analysis. According to the class limits established, selective accuracy and F-test values for genotype, heritability, and the coefficient of determination adequately estimated the degree of experimental precision. Using these statistics, 86.21% of the trials had adequate experimental precision. Selective accuracy and the F-test values for genotype, heritability, and the coefficient of determination were directly related to each other, and were more suitable than the coefficient of variation and the least significant difference (by the Tukey test) to evaluate experimental precision in trials with cowpea genotypes.

Population genetics of apolipoprotein A-4, E, and H polymorphisms in Yanomami Indians of northwestern Brazil: associations with lipids, lipoproteins, and carbohydrate metabolism.

PubMed

Crews, D E; Kamboh, M I; Mancilha-Carvalho, J J; Kottke, B

1993-04-01

Using isoelectric focusing and immunoblotting techniques, we screened 96 serum samples from Yanomami Indians of northwestern Brazil to determine structural variation at three apolipoprotein loci: A4, E, and H. The APO-H locus, which is commonly polymorphic in white and black samples, was found to be monomorphic. At the APO-E locus only two alleles, APOE*3 and APOE*4, rather than the three-allele polymorphism commonly seen in Caucasians, was observed. At the APO-A4 locus no example of the APOA4*2 allele, found in Caucasians, was detected. However, the frequency of the less common APOA4*4 allele was above what has been observed in any other population. We investigated the impact of genetic variation at both polymorphic loci on quantitative differences in lipids, apolipoproteins, serum glucose, glycated hemoglobin, and uric acid. Contrary to the cholesterol-elevating effect of APOE*4 reported elsewhere, in both univariate analyses and after adjustments for age, sex, weight, and height, APOE*4 was associated with about a 4% lower mean serum cholesterol. Only after adjustment was this association statistically significant. The APOE*4 allele was significantly associated with unadjusted APO-A1 and APO-E levels but not with any other dependent variable; associations with adjusted APO-A1, APO-C2, and uric acid also approached standard levels of statistical significance (p < or = 0.05). In univariate analyses the APOA4*4 allele was significantly associated with APO-B, serum glucose, percent glycated hemoglobin, and uric acid, but no significant associations were observed after dependent variables were adjusted for age, sex, weight, and height. These results support the notion that apolipoprotein distributions and their associations with lipid and carbohydrate metabolism show ethnic variability.

Assessment of the beryllium lymphocyte proliferation test using statistical process control.

PubMed

Cher, Daniel J; Deubner, David C; Kelsh, Michael A; Chapman, Pamela S; Ray, Rose M

2006-10-01

Despite more than 20 years of surveillance and epidemiologic studies using the beryllium blood lymphocyte proliferation test (BeBLPT) as a measure of beryllium sensitization (BeS) and as an aid for diagnosing subclinical chronic beryllium disease (CBD), improvements in specific understanding of the inhalation toxicology of CBD have been limited. Although epidemiologic data suggest that BeS and CBD risks vary by process/work activity, it has proven difficult to reach specific conclusions regarding the dose-response relationship between workplace beryllium exposure and BeS or subclinical CBD. One possible reason for this uncertainty could be misclassification of BeS resulting from variation in BeBLPT testing performance. The reliability of the BeBLPT, a biological assay that measures beryllium sensitization, is unknown. To assess the performance of four laboratories that conducted this test, we used data from a medical surveillance program that offered testing for beryllium sensitization with the BeBLPT. The study population was workers exposed to beryllium at various facilities over a 10-year period (1992-2001). Workers with abnormal results were offered diagnostic workups for CBD. Our analyses used a standard statistical technique, statistical process control (SPC), to evaluate test reliability. The study design involved a repeated measures analysis of BeBLPT results generated from the company-wide, longitudinal testing. Analytical methods included use of (1) statistical process control charts that examined temporal patterns of variation for the stimulation index, a measure of cell reactivity to beryllium; (2) correlation analysis that compared prior perceptions of BeBLPT instability to the statistical measures of test variation; and (3) assessment of the variation in the proportion of missing test results and how time periods with more missing data influenced SPC findings. During the period of this study, all laboratories displayed variation in test results that were beyond what would be expected due to chance alone. Patterns of test results suggested that variations were systematic. We conclude that laboratories performing the BeBLPT or other similar biological assays of immunological response could benefit from a statistical approach such as SPC to improve quality management.

Variation in cannabis potency and prices in a newly legal market: evidence from 30 million cannabis sales in Washington state.

PubMed

Smart, Rosanna; Caulkins, Jonathan P; Kilmer, Beau; Davenport, Steven; Midgette, Greg

2017-12-01

To (1) assess trends and variation in the market share of product types and potency sold in a legal cannabis retail market and (2) estimate how potency and purchase quantity influence price variation for cannabis flower. Secondary analysis of publicly available data from Washington State's cannabis traceability system spanning 7 July 2014 to 30 September 2016. Descriptive statistics and linear regressions assessed variation and trends in cannabis product variety and potency. Hedonic regressions estimated how purchase quantity and potency influence cannabis flower price variation. Washington State, USA. (1) A total of 44 482 176 million cannabis purchases, including (2) 31 052 123 cannabis flower purchases after trimming price and quantity outliers. Primary outcome measures were (1) monthly expenditures on cannabis, total delta-9-tetrahydrocannabinol (THC) concentration and cannabidiol (CBD) concentration by product type and (2) excise tax-inclusive price per gram of cannabis flower. Key covariates for the hedonic price regressions included quantity purchased, THC and CBD. Traditional cannabis flowers still account for the majority of spending (66.6%), but the market share of extracts for inhalation increased by 145.8% between October 2014 and September 2016, now comprising 21.2% of sales. The average THC-level for cannabis extracts is more than triple that for cannabis flowers (68.7% compared to 20.6%). For flower products, there is a statistically significant relationship between price per gram and both THC [coefficient = 0.012; 95% confidence interval (CI) = 0.011-0.013] and CBD (coefficient = 0.017; CI = 0.015-0.019). The estimated discount elasticity is -0.06 (CI = -0.07 to -0.05). In the state of Washington, USA, the legal cannabis market is currently dominated by high-THC cannabis flower, and features growing expenditures on extracts. For cannabis flower, both THC and CBD are associated with higher per-gram prices, and there are small but significant quantity discounts. © 2017 Society for the Study of Addiction.

Accounting for multiple climate components when estimating climate change exposure and velocity

USGS Publications Warehouse

Nadeau, Christopher P.; Fuller, Angela K.

2015-01-01

The effect of anthropogenic climate change on organisms will likely be related to climate change exposure and velocity at local and regional scales. However, common methods to estimate climate change exposure and velocity ignore important components of climate that are known to affect the ecology and evolution of organisms.We develop a novel index of climate change (climate overlap) that simultaneously estimates changes in the means, variation and correlation between multiple weather variables. Specifically, we estimate the overlap between multivariate normal probability distributions representing historical and current or projected future climates. We provide methods for estimating the statistical significance of climate overlap values and methods to estimate velocity using climate overlap.We show that climates have changed significantly across 80% of the continental United States in the last 32 years and that much of this change is due to changes in the variation and correlation between weather variables (two statistics that are rarely incorporated into climate change studies). We also show that projected future temperatures are predicted to be locally novel (<1·5% overlap) across most of the global land surface and that exposure is likely to be highest in areas with low historical climate variation. Last, we show that accounting for changes in the variation and correlation between multiple weather variables can dramatically affect velocity estimates; mean velocity estimates in the continental United States were between 3·1 and 19·0 km yr−1when estimated using climate overlap compared to 1·4 km yr−1 when estimated using traditional methods.Our results suggest that accounting for changes in the means, variation and correlation between multiple weather variables can dramatically affect estimates of climate change exposure and velocity. These climate components are known to affect the ecology and evolution of organisms, but are ignored by most measures of climate change. We conclude with a set of future directions and recommend future work to determine which measures of climate change exposure and velocity are most related to biological responses to climate change.

Improving DHH students' grammar through an individualized software program.

PubMed

Cannon, Joanna E; Easterbrooks, Susan R; Gagné, Phill; Beal-Alvarez, Jennifer

2011-01-01

The purpose of this study was to determine if the frequent use of a targeted, computer software grammar instruction program, used as an individualized classroom activity, would influence the comprehension of morphosyntax structures (determiners, tense, and complementizers) in deaf/hard-of-hearing (DHH) participants who use American Sign Language (ASL). Twenty-six students from an urban day school for the deaf participated in this study. Two hierarchical linear modeling growth curve analyses showed that the influence of LanguageLinks: Syntax Assessment and Intervention (LL) resulted in statistically significant gains in participants' comprehension of morphosyntax structures. Two dependent t tests revealed statistically significant results between the pre- and postintervention assessments on the Diagnostic Evaluation of Language Variation-Norm Referenced. The daily use of LL increased the morphosyntax comprehension of the participants in this study and may be a promising practice for DHH students who use ASL.

Response to Comment on "Does the Earth Have an Adaptive Infrared IRIS?"

NASA Technical Reports Server (NTRS)

Bell, Thomas L.; Chou, Ming-Dah; Lindzen, Richard S.; Hou, Arthur Y.

2001-01-01

Harrison's (2001) Comment on the Methodology in Lindzen et al (2001) has prompted re-examination of several aspects of study. Probably the most significant disagreement in our conclusions is due to our different approaches to minimizing the influence of long-time-scale variations in the variables A and T on the results. Given the strength of the annual cycle and the 20-month period covered by the data, we believe that removing monthly means is a better approach to minimizing the long-time-scale behavior of the data than removal of the linear trend, which might actually add spurious long- time- scale variability into the modified data. We have also indicated how our statistical methods of establishing statistical significance differ. More definitive conclusions may only possible after more data have been analyzed, but we feel that our results are robust enough to encourage further study of this phenomenon.

Colorectal cancer mutational profiles correlate with defined microbial communities in the tumor microenvironment.

PubMed

Burns, Michael B; Montassier, Emmanuel; Abrahante, Juan; Priya, Sambhawa; Niccum, David E; Khoruts, Alexander; Starr, Timothy K; Knights, Dan; Blekhman, Ran

2018-06-20

Variation in the gut microbiome has been linked to colorectal cancer (CRC), as well as to host genetic variation. However, we do not know whether, in addition to baseline host genetics, somatic mutational profiles in CRC tumors interact with the surrounding tumor microbiome, and if so, whether these changes can be used to understand microbe-host interactions with potential functional biological relevance. Here, we characterized the association between CRC microbial communities and tumor mutations using microbiome profiling and whole-exome sequencing in 44 pairs of tumors and matched normal tissues. We found statistically significant associations between loss-of-function mutations in tumor genes and shifts in the abundances of specific sets of bacterial taxa, suggestive of potential functional interaction. This correlation allows us to statistically predict interactions between loss-of-function tumor mutations in cancer-related genes and pathways, including MAPK and Wnt signaling, solely based on the composition of the microbiome. In conclusion, our study shows that CRC microbiomes are correlated with tumor mutational profiles, pointing towards possible mechanisms of molecular interaction.

Statistical modeling of SRAM yield performance and circuit variability

NASA Astrophysics Data System (ADS)

Cheng, Qi; Chen, Yijian

2015-03-01

In this paper, we develop statistical models to investigate SRAM yield performance and circuit variability in the presence of self-aligned multiple patterning (SAMP) process. It is assumed that SRAM fins are fabricated by a positivetone (spacer is line) self-aligned sextuple patterning (SASP) process which accommodates two types of spacers, while gates are fabricated by a more pitch-relaxed self-aligned quadruple patterning (SAQP) process which only allows one type of spacer. A number of possible inverter and SRAM structures are identified and the related circuit multi-modality is studied using the developed failure-probability and yield models. It is shown that SRAM circuit yield is significantly impacted by the multi-modality of fins' spatial variations in a SRAM cell. The sensitivity of 6-transistor SRAM read/write failure probability to SASP process variations is calculated and the specific circuit type with the highest probability to fail in the reading/writing operation is identified. Our study suggests that the 6-transistor SRAM configuration may not be scalable to 7-nm half pitch and more robust SRAM circuit design needs to be researched.

Correlation between occlusion and cervical posture in patients with bruxism.

PubMed

Cesar, Guilherme Manna; Tosato, Juliana de Paiva; Biasotto-Gonzalez, Daniela Ap

2006-08-01

The goal of this study was to evaluate head and neck posture in the rest position of patients with bruxism and patients without temporomandibular disorder signs or symptoms to further relate them with Angle's class of malocclusion. Fifty-six volunteers participated in this study, ages 18 to 27 years with an average age of 22.5 years. They were divided into 2 groups: Group B--28 subjects with parafunctions (teeth grinding or clenching); and Group C--28 subjects without parafunctional habits (control group). All participants were photographed, and their pictures were analyzed and compared with the software Alcimagem (Instrumental Concept and Movement Analysis Laboratory, Uberlândia, Minas Gerais, Brazil). The results demonstrated that variation of angular values did not present statistical difference for the studied groups. Regarding Angle's class of malocclusion, class I was predominant in Group C, and classes II and III were predominant in Group B. The mental-sternal angle calculated did not present statistical significance between the groups; however, there was a greater variation between the smaller angle and the higher angle in Group B, contrary to Group C.

Runoff response to climate change and human activities in a typical karst watershed, SW China.

PubMed

Xu, Yan; Wang, Shijie; Bai, Xiaoyong; Shu, Dongcai; Tian, Yichao

2018-01-01

This study aims to reveal the runoff variation characteristics of long time series in a karst region, analyse comprehensively its different driving factors, and estimate quantitatively the contribution rates of climate change and human activities to net runoff variation. Liudong river basin, a typical karst watershed in southwest China, is the study site. Statistical methods, such as linear fitting, the Morlet wavelet analysis, normalized curve and double mass curve, are applied to analyse the runoff of the watershed. Results show that the runoff in the karst watershed during the research period exhibits a three-stage change and the abrupt change points are the years 1981 and 2007: (1) 1968-1980, the runoff initially exhibited a trend of sustained decreasing and then an abrupt fluctuation. The runoff was obviously destroyed through precipitation-producing processes. Improper land utilisation and serious forest and grass destruction intensified the fluctuation variation amplitude of the runoff. (2) 1981-2006, the changing processes of runoff and precipitation exhibited good synchronism. Precipitation significantly affected runoff variation and human activities had a slight interference degree. (3) 2007-2013, the fluctuation range of runoff was considerably smaller than that of precipitation. The significant growth of forest and grassland areas and the increase in water consumption mitigated runoff fluctuation and greatly diminished runoff variation amplitude. According to calculation, the relative contribution rates of precipitation and human activities to net runoff variation with 1981-2007 as the reference period were -81% and 181% in average, respectively, during 1968-1980, and -117% and 217% in average, respectively, during 2007-2013. In general, the analysis of runoff variation trend and of the contribution rate of its main influencing factors in the typical karst watershed for nearly half a century may be significant to solve the drought problem in the karst region and for the sustainable development of the drainage basin.

Runoff response to climate change and human activities in a typical karst watershed, SW China

PubMed Central

Xu, Yan; Wang, Shijie; Shu, Dongcai; Tian, Yichao

2018-01-01

This study aims to reveal the runoff variation characteristics of long time series in a karst region, analyse comprehensively its different driving factors, and estimate quantitatively the contribution rates of climate change and human activities to net runoff variation. Liudong river basin, a typical karst watershed in southwest China, is the study site. Statistical methods, such as linear fitting, the Morlet wavelet analysis, normalized curve and double mass curve, are applied to analyse the runoff of the watershed. Results show that the runoff in the karst watershed during the research period exhibits a three-stage change and the abrupt change points are the years 1981 and 2007: (1) 1968–1980, the runoff initially exhibited a trend of sustained decreasing and then an abrupt fluctuation. The runoff was obviously destroyed through precipitation-producing processes. Improper land utilisation and serious forest and grass destruction intensified the fluctuation variation amplitude of the runoff. (2) 1981–2006, the changing processes of runoff and precipitation exhibited good synchronism. Precipitation significantly affected runoff variation and human activities had a slight interference degree. (3) 2007–2013, the fluctuation range of runoff was considerably smaller than that of precipitation. The significant growth of forest and grassland areas and the increase in water consumption mitigated runoff fluctuation and greatly diminished runoff variation amplitude. According to calculation, the relative contribution rates of precipitation and human activities to net runoff variation with 1981–2007 as the reference period were −81% and 181% in average, respectively, during 1968–1980, and −117% and 217% in average, respectively, during 2007–2013. In general, the analysis of runoff variation trend and of the contribution rate of its main influencing factors in the typical karst watershed for nearly half a century may be significant to solve the drought problem in the karst region and for the sustainable development of the drainage basin. PMID:29494602

Regional variation in the severity of pesticide exposure outcomes: applications of geographic information systems and spatial scan statistics.

PubMed

Sudakin, Daniel L; Power, Laura E

2009-03-01

Geographic information systems and spatial scan statistics have been utilized to assess regional clustering of symptomatic pesticide exposures reported to a state Poison Control Center (PCC) during a single year. In the present study, we analyzed five subsequent years of PCC data to test whether there are significant geographic differences in pesticide exposure incidents resulting in serious (moderate, major, and fatal) medical outcomes. A PCC provided the data on unintentional pesticide exposures for the time period 2001-2005. The geographic location of the caller, the location where the exposure occurred, the exposure route, and the medical outcome were abstracted. There were 273 incidents resulting in moderate effects (n = 261), major effects (n = 10), or fatalities (n = 2). Spatial scan statistics identified a geographic area consisting of two adjacent counties (one urban, one rural), where statistically significant clustering of serious outcomes was observed. The relative risk of moderate, major, and fatal outcomes was 2.0 in this spatial cluster (p = 0.0005). PCC data, geographic information systems, and spatial scan statistics can identify clustering of serious outcomes from human exposure to pesticides. These analyses may be useful for public health officials to target preventive interventions. Further investigation is warranted to understand better the potential explanations for geographical clustering, and to assess whether preventive interventions have an impact on reducing pesticide exposure incidents resulting in serious medical outcomes.

Research participant compensation: A matter of statistical inference as well as ethics.

PubMed

Swanson, David M; Betensky, Rebecca A

2015-11-01

The ethics of compensation of research subjects for participation in clinical trials has been debated for years. One ethical issue of concern is variation among subjects in the level of compensation for identical treatments. Surprisingly, the impact of variation on the statistical inferences made from trial results has not been examined. We seek to identify how variation in compensation may influence any existing dependent censoring in clinical trials, thereby also influencing inference about the survival curve, hazard ratio, or other measures of treatment efficacy. In simulation studies, we consider a model for how compensation structure may influence the censoring model. Under existing dependent censoring, we estimate survival curves under different compensation structures and observe how these structures induce variability in the estimates. We show through this model that if the compensation structure affects the censoring model and dependent censoring is present, then variation in that structure induces variation in the estimates and affects the accuracy of estimation and inference on treatment efficacy. From the perspectives of both ethics and statistical inference, standardization and transparency in the compensation of participants in clinical trials are warranted. Copyright © 2015 Elsevier Inc. All rights reserved.

Rain attenuation measurements: Variability and data quality assessment

NASA Technical Reports Server (NTRS)

Crane, Robert K.

1989-01-01

Year to year variations in the cumulative distributions of rain rate or rain attenuation are evident in any of the published measurements for a single propagation path that span a period of several years of observation. These variations must be described by models for the prediction of rain attenuation statistics. Now that a large measurement data base has been assembled by the International Radio Consultative Committee, the information needed to assess variability is available. On the basis of 252 sample cumulative distribution functions for the occurrence of attenuation by rain, the expected year to year variation in attenuation at a fixed probability level in the 0.1 to 0.001 percent of a year range is estimated to be 27 percent. The expected deviation from an attenuation model prediction for a single year of observations is estimated to exceed 33 percent when any of the available global rain climate model are employed to estimate the rain rate statistics. The probability distribution for the variation in attenuation or rain rate at a fixed fraction of a year is lognormal. The lognormal behavior of the variate was used to compile the statistics for variability.

Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Power, S.; Mirza, M.; Thakorlal, A.

PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used tomore » measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.« less

Influence of increment thickness on the similarity of composite shade: a pilot study.

PubMed

Roselino, Lourenco de Moraes Rego; Garcia, Lucas da Fonseca Roberti; Sousa, Ana Beatriz Silva; Pires-de-Souza, Fernanda de Carvalho Panzeri

2012-01-01

The aim of this study was to evaluate the similarity in shade between increments of different composite thicknesses. Fifty test specimens 12 mm in diameter were fabricated and separated into five groups (n = 10) according to sample thickness: 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, and 2.5 mm. Specimens were polished with water abrasive papers and silicone points. Next, based on the CIE L*a*b* system, test specimens were submitted to color readouts, and the values obtained for the coordinates L*, a*, and b* for each thickness were compared using one-way ANOVA and a Tukey test (P < 0.05). The results demonstrated that there was a reduction in coordinate L* as the test specimen thickness increased, with statistically significant differences (P < 0.05), except for 2.0 mm and 2.5 mm thicknesses (P > 0.05). Samples 1.5 mm thick presented less variation of a*, while a greater variation occurred for samples 2.5 mm thick, with a significant difference in comparison with the other thicknesses (P < 0.05), except for 2.0 mm (P > 0.05). Samples 0.5 mm thick presented a greater variation of b*, while the lowest variation in this coordinate occurred for samples 2.5 mm thick, which was significantly different from the other samples (P < 0.05). It was concluded that different composite thicknesses do not present similarity of color and have an influence on the final result of esthetic restorations.

Lack of Day/Night variation in fibroblast growth factor 21 levels in young healthy men.

PubMed

Foo, J-P; Aronis, K N; Chamberland, J P; Mantzoros, C S

2015-06-01

Fibroblast growth factor (FGF) 21 is an endocrine factor with an emerging role as a metabolic regulator. We previously reported the presence of a significant day/night variation of FGF-21 in energy-replete, healthy female subjects. However the day/night patterns of secretion in male subjects remain to be fully elucidated. To elucidate day/night pattern of FGF-21 levels in male subjects in the energy-replete state, its relationship to FFA and to investigate whether a sexual dimorphism exists in FGF-21 physiology. Eight healthy lean male subjects were studied for up to 5 days while on an isocaloric diet. Blood samples were obtained for measurement of FGF-21 and free fatty acids (FFA) hourly from 0800 AM on day 4 till 0800AM on day 5. FGF-21 did not exhibit any statistically significant day/night variation pattern of circulating FGF-21 levels during the isocaloric fed state in male subjects. FGF-21 levels in male subjects are closely cross-correlated with FFA levels, similar to female subjects. A sexual dimorphism exists in FGF-21 physiology; that as opposed to female subjects, no significant day/night variation exists in FGF-21 rhythm in male subjects in the energy-replete state. Circulating pattern of FGF-21, similar to the female subjects, was highly cross-correlated to the FFA levels in the male subjects, signifying that the sexual dimorphism in FGF-21 physiology may be related to the differing lipid metabolism in both the genders.

Geographic Variation in Rosiglitazone Use Surrounding FDA Warnings in the Department of Veterans Affairs.

PubMed

Ahuja, Vishal; Sohn, Min-Woong; Birge, John R; Syverson, Chad; Budiman-Mak, Elly; Emanuele, Nicholas; Cooper, Jennifer M; Huang, Elbert S

2015-12-01

Geographic variation in the use of prescription drugs, particularly those deemed harmful by the FDA, may lead to variation in patient exposure to adverse drug events. One such drug is the glucose-lowering drug rosiglitazone, for which the FDA issued a safety alert on May 21, 2007, following the publication of a meta-analysis that suggested a 43% increase in the risk of myocardial infarction with the use of rosiglitazone. This alert was followed by a black box warning on August 14, 2007, that was updated 3 months later. While large declines have been documented in rosiglitazone use in clinical practice, little is known about how the use of rosiglitazone and other glucose-lowering drugs varied within the Department of Veterans Affairs (VA), surrounding the FDA alerts. Understanding this variation within integrated health care systems is essential to formulating policies that enhance patient protection and quality of care. To document variation in the use of rosiglitazone and other glucose- lowering drugs across 21 Veterans Integrated Service Networks (VISNs). We conducted a retrospective analysis of drug use patterns for all major diabetes drugs in a national cohort of 550,550 veterans with diabetes from 2003 to 2008. This included the time periods when rosiglitazone was added to (November 2003) and removed from (October 2007) the VA national formulary (VANF). We employed multivariable logistic regression models to statistically estimate the association between a patient's location and the patient's odds of using rosiglitazone. Aggregate rosiglitazone use increased monotonically from 7.7%, in the quarter it was added to the VANF (November 4, 2003), to a peak of 15.3% in the quarter when the FDA issued the safety alert. Rosiglitazone use decreased sharply afterwards, reaching 3.4% by the end of the study period (September 30, 2008). The use of pioglitazone, another glucose-lowering drug in the same class as rosiglitazone, was low when the FDA issued the safety alert (0.4%) but increased sharply afterwards, reaching 3.6% by the end of the study period. Insulin use increased monotonically; metformin use remained relatively flat; and sulfonylurea use exhibited a general declining trend throughout the study period. Statistically significant geographic variation was observed in rosiglitazone use throughout the study period. The prevalence range, defined as the range of minimum to maximum use across VISNs was 3.7%-12.4% in the first quarter (January 1 to March 31, 2003); 1.0%-5.5% in the last quarter of study period (July 1 to September 30, 2008); and reached a peak of 9.6%-25.5% in the quarter when the FDA safety alert was issued (April 1 to March 31, 2007). In 5 VISNs, peak rosiglitazone use occurred before the FDA issued the safety alert. The odds ratio of using rosiglitazone in a given VISN varied from 0.55 (95% CI = 0.52-0.59; VISN 10) to 1.58 (95% CI = 1.50-1.66; VISN 15), with VISN 1 being the reference region. The variation was higher in the periods after the FDA issued the safety alert. Much less variation was observed in the use of pioglitazone, metformin, sulfonylurea, and insulin. Our results show statistically significant variation in the way VISNs within the VA responded to the FDA alerts, suggesting a need for mechanisms that disseminate information and guidelines for drug use in a consistent and reliable manner. Further study of regions that adopted ideal practices earlier may provide lessons for regional leadership and practice culture within integrated health care systems.

Landscape complexity and soil moisture variation in south Georgia, USA, for remote sensing applications

NASA Astrophysics Data System (ADS)

Giraldo, Mario A.; Bosch, David; Madden, Marguerite; Usery, Lynn; Kvien, Craig

2008-08-01

SummaryThis research addressed the temporal and spatial variation of soil moisture (SM) in a heterogeneous landscape. The research objective was to investigate soil moisture variation in eight homogeneous 30 by 30 m plots, similar to the pixel size of a Landsat Thematic Mapper (TM) or Enhanced Thematic Mapper plus (ETM+) image. The plots were adjacent to eight stations of an in situ soil moisture network operated by the United States Department of Agriculture-Agriculture Research Service USDA-ARS in Tifton, GA. We also studied five adjacent agricultural fields to examine the effect of different landuses/land covers (LULC) (grass, orchard, peanuts, cotton and bare soil) on the temporal and spatial variation of soil moisture. Soil moisture field data were collected on eight occasions throughout 2005 and January 2006 to establish comparisons within and among eight homogeneous plots. Consistently throughout time, analysis of variance (ANOVA) showed high variation in the soil moisture behavior among the plots and high homogeneity in the soil moisture behavior within them. A precipitation analysis for the eight sampling dates throughout the year 2005 showed similar rainfall conditions for the eight study plots. Therefore, soil moisture variation among locations was explained by in situ local conditions. Temporal stability geostatistical analysis showed that soil moisture has high temporal stability within the small plots and that a single point reading can be used to monitor soil moisture status for the plot within a maximum 3% volume/volume (v/v) soil moisture variation. Similarly, t-statistic analysis showed that soil moisture status in the upper soil layer changes within 24 h. We found statistical differences in the soil moisture between the different LULC in the agricultural fields as well as statistical differences between these fields and the adjacent 30 by 30 m plots. From this analysis, it was demonstrated that spatial proximity is not enough to produce similar soil moisture, since t-test's among adjacent plots with different LULCs showed significant differences. These results confirm that a remote sensing approach that considers homogeneous LULC landscape fragments can be used to identify landscape units of similar soil moisture behavior under heterogeneous landscapes. In addition, the in situ USDA-ARS network will serve better in remote sensing studies in which sensors with fine spatial resolution are evaluated. This study is a first step towards identifying landscape units that can be monitored using the single point reading of the USDA-ARS stations network.

Landscape complexity and soil moisture variation in south Georgia, USA, for remote sensing applications

USGS Publications Warehouse

Giraldo, M.A.; Bosch, D.; Madden, M.; Usery, L.; Kvien, Craig

2008-01-01

This research addressed the temporal and spatial variation of soil moisture (SM) in a heterogeneous landscape. The research objective was to investigate soil moisture variation in eight homogeneous 30 by 30 m plots, similar to the pixel size of a Landsat Thematic Mapper (TM) or Enhanced Thematic Mapper plus (ETM+) image. The plots were adjacent to eight stations of an in situ soil moisture network operated by the United States Department of Agriculture-Agriculture Research Service USDA-ARS in Tifton, GA. We also studied five adjacent agricultural fields to examine the effect of different landuses/land covers (LULC) (grass, orchard, peanuts, cotton and bare soil) on the temporal and spatial variation of soil moisture. Soil moisture field data were collected on eight occasions throughout 2005 and January 2006 to establish comparisons within and among eight homogeneous plots. Consistently throughout time, analysis of variance (ANOVA) showed high variation in the soil moisture behavior among the plots and high homogeneity in the soil moisture behavior within them. A precipitation analysis for the eight sampling dates throughout the year 2005 showed similar rainfall conditions for the eight study plots. Therefore, soil moisture variation among locations was explained by in situ local conditions. Temporal stability geostatistical analysis showed that soil moisture has high temporal stability within the small plots and that a single point reading can be used to monitor soil moisture status for the plot within a maximum 3% volume/volume (v/v) soil moisture variation. Similarly, t-statistic analysis showed that soil moisture status in the upper soil layer changes within 24 h. We found statistical differences in the soil moisture between the different LULC in the agricultural fields as well as statistical differences between these fields and the adjacent 30 by 30 m plots. From this analysis, it was demonstrated that spatial proximity is not enough to produce similar soil moisture, since t-test's among adjacent plots with different LULCs showed significant differences. These results confirm that a remote sensing approach that considers homogeneous LULC landscape fragments can be used to identify landscape units of similar soil moisture behavior under heterogeneous landscapes. In addition, the in situ USDA-ARS network will serve better in remote sensing studies in which sensors with fine spatial resolution are evaluated. This study is a first step towards identifying landscape units that can be monitored using the single point reading of the USDA-ARS stations network. ?? 2008 Elsevier B.V.

Allelic variation in Salmonella: an underappreciated driver of adaptation and virulence

PubMed Central

Yue, Min; Schifferli, Dieter M.

2014-01-01

Salmonella enterica causes substantial morbidity and mortality in humans and animals. Infection and intestinal colonization by S. enterica require virulence factors that mediate bacterial binding and invasion of enterocytes and innate immune cells. Some S. enterica colonization factors and their alleles are host restricted, suggesting a potential role in regulation of host specificity. Recent data also suggest that colonization factors promote horizontal gene transfer of antimicrobial resistance genes by increasing the local density of Salmonella in colonized intestines. Although a profusion of genes are involved in Salmonella pathogenesis, the relative importance of their allelic variation has only been studied intensely in the type 1 fimbrial adhesin FimH. Although other Salmonella virulence factors demonstrate allelic variation, their association with specific metadata (e.g., host species, disease or carrier state, time and geographic place of isolation, antibiotic resistance profile, etc.) remains to be interrogated. To date, genome-wide association studies (GWAS) in bacteriology have been limited by the paucity of relevant metadata. In addition, due to the many variables amid metadata categories, a very large number of strains must be assessed to attain statistically significant results. However, targeted approaches in which genes of interest (e.g., virulence factors) are specifically sequenced alleviates the time-consuming and costly statistical GWAS analysis and increases statistical power, as larger numbers of strains can be screened for non-synonymous single nucleotide polymorphisms (SNPs) that are associated with available metadata. Congruence of specific allelic variants with specific metadata from strains that have a relevant clinical and epidemiological history will help to prioritize functional wet-lab and animal studies aimed at determining cause-effect relationships. Such an approach should be applicable to other pathogens that are being collected in well-curated repositories. PMID:24454310

Statistical Exposé of a Multiple-Compartment Anaerobic Reactor Treating Domestic Wastewater.

PubMed

Pfluger, Andrew R; Hahn, Martha J; Hering, Amanda S; Munakata-Marr, Junko; Figueroa, Linda

2018-06-01

  Mainstream anaerobic treatment of domestic wastewater is a promising energy-generating treatment strategy; however, such reactors operated in colder regions are not well characterized. Performance data from a pilot-scale, multiple-compartment anaerobic reactor taken over 786 days were subjected to comprehensive statistical analyses. Results suggest that chemical oxygen demand (COD) was a poor proxy for organics in anaerobic systems as oxygen demand from dissolved inorganic material, dissolved methane, and colloidal material influence dissolved and particulate COD measurements. Additionally, univariate and functional boxplots were useful in visualizing variability in contaminant concentrations and identifying statistical outliers. Further, significantly different dissolved organic removal and methane production was observed between operational years, suggesting that anaerobic reactor systems may not achieve steady-state performance within one year. Last, modeling multiple-compartment reactor systems will require data collected over at least two years to capture seasonal variations of the major anaerobic microbial functions occurring within each reactor compartment.

To P or Not to P: Backing Bayesian Statistics.

PubMed

Buchinsky, Farrel J; Chadha, Neil K

2017-12-01

In biomedical research, it is imperative to differentiate chance variation from truth before we generalize what we see in a sample of subjects to the wider population. For decades, we have relied on null hypothesis significance testing, where we calculate P values for our data to decide whether to reject a null hypothesis. This methodology is subject to substantial misinterpretation and errant conclusions. Instead of working backward by calculating the probability of our data if the null hypothesis were true, Bayesian statistics allow us instead to work forward, calculating the probability of our hypothesis given the available data. This methodology gives us a mathematical means of incorporating our "prior probabilities" from previous study data (if any) to produce new "posterior probabilities." Bayesian statistics tell us how confidently we should believe what we believe. It is time to embrace and encourage their use in our otolaryngology research.

A non-linear dimension reduction methodology for generating data-driven stochastic input models

NASA Astrophysics Data System (ADS)

Ganapathysubramanian, Baskar; Zabaras, Nicholas

2008-06-01

Stochastic analysis of random heterogeneous media (polycrystalline materials, porous media, functionally graded materials) provides information of significance only if realistic input models of the topology and property variations are used. This paper proposes a framework to construct such input stochastic models for the topology and thermal diffusivity variations in heterogeneous media using a data-driven strategy. Given a set of microstructure realizations (input samples) generated from given statistical information about the medium topology, the framework constructs a reduced-order stochastic representation of the thermal diffusivity. This problem of constructing a low-dimensional stochastic representation of property variations is analogous to the problem of manifold learning and parametric fitting of hyper-surfaces encountered in image processing and psychology. Denote by M the set of microstructures that satisfy the given experimental statistics. A non-linear dimension reduction strategy is utilized to map M to a low-dimensional region, A. We first show that M is a compact manifold embedded in a high-dimensional input space Rn. An isometric mapping F from M to a low-dimensional, compact, connected set A⊂Rd(d≪n) is constructed. Given only a finite set of samples of the data, the methodology uses arguments from graph theory and differential geometry to construct the isometric transformation F:M→A. Asymptotic convergence of the representation of M by A is shown. This mapping F serves as an accurate, low-dimensional, data-driven representation of the property variations. The reduced-order model of the material topology and thermal diffusivity variations is subsequently used as an input in the solution of stochastic partial differential equations that describe the evolution of dependant variables. A sparse grid collocation strategy (Smolyak algorithm) is utilized to solve these stochastic equations efficiently. We showcase the methodology by constructing low-dimensional input stochastic models to represent thermal diffusivity in two-phase microstructures. This model is used in analyzing the effect of topological variations of two-phase microstructures on the evolution of temperature in heat conduction processes.

Metabolic effects of large-volume liposuction for obese healthy women: a meta-analysis of fasting insulin levels.

PubMed

Boriani, Filippo; Villani, Riccardo; Morselli, Paolo Giovanni

2014-10-01

Obesity is increasingly frequent in our society and is associated closely with metabolic disorders. As some studies have suggested, removal of fat tissue through liposuction and dermolipectomies may be of some benefit in the improvement of metabolic indices. This article aimed to review the published literature on this topic and to evaluate metabolic variations meta-analytically after liposuction, dermolipectomy, or both. Through a literature search with the PubMed/Medline database, 14 studies were identified. All articles were analyzed, and several metabolic variables were chosen in the attempt to meta-analyze the effect of adipose tissue removal through the various studies. All statistical calculations were performed with Review Manager (RevMan), version 5.0. Several cardiovascular and metabolic variables are described as prone to variations after body-contouring procedures when a significant amount of adipose tissue has been excised. Four of the studies included in the analysis reported improvements in all the parameters examined. Seven articles showed improvement in some variables and no improvement in others, whereas three studies showed no beneficial variation in any of the considered indicators after body-contouring procedures. Fasting plasma insulin was identified as the only variable for which a meta-analysis of five included studies was possible. The meta-analysis showed a statistically significant reduction in fasting plasma insulin resulting from large-volume liposuction in obese healthy women. Many beneficial metabolic effects resulting from dermolipectomy and liposuction procedures are described in the literature. In particular, fasting plasma insulin and thus insulin sensitivity seem to be positively influenced. Further research, including prospective clinical studies, is necessary for better exploration of the effects that body-contouring plastic surgery procedures have on metabolic parameters.

Individualized statistical learning from medical image databases: application to identification of brain lesions.

PubMed

Erus, Guray; Zacharaki, Evangelia I; Davatzikos, Christos

2014-04-01

This paper presents a method for capturing statistical variation of normal imaging phenotypes, with emphasis on brain structure. The method aims to estimate the statistical variation of a normative set of images from healthy individuals, and identify abnormalities as deviations from normality. A direct estimation of the statistical variation of the entire volumetric image is challenged by the high-dimensionality of images relative to smaller sample sizes. To overcome this limitation, we iteratively sample a large number of lower dimensional subspaces that capture image characteristics ranging from fine and localized to coarser and more global. Within each subspace, a "target-specific" feature selection strategy is applied to further reduce the dimensionality, by considering only imaging characteristics present in a test subject's images. Marginal probability density functions of selected features are estimated through PCA models, in conjunction with an "estimability" criterion that limits the dimensionality of estimated probability densities according to available sample size and underlying anatomy variation. A test sample is iteratively projected to the subspaces of these marginals as determined by PCA models, and its trajectory delineates potential abnormalities. The method is applied to segmentation of various brain lesion types, and to simulated data on which superiority of the iterative method over straight PCA is demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

Individualized Statistical Learning from Medical Image Databases: Application to Identification of Brain Lesions

PubMed Central

Erus, Guray; Zacharaki, Evangelia I.; Davatzikos, Christos

2014-01-01

This paper presents a method for capturing statistical variation of normal imaging phenotypes, with emphasis on brain structure. The method aims to estimate the statistical variation of a normative set of images from healthy individuals, and identify abnormalities as deviations from normality. A direct estimation of the statistical variation of the entire volumetric image is challenged by the high-dimensionality of images relative to smaller sample sizes. To overcome this limitation, we iteratively sample a large number of lower dimensional subspaces that capture image characteristics ranging from fine and localized to coarser and more global. Within each subspace, a “target-specific” feature selection strategy is applied to further reduce the dimensionality, by considering only imaging characteristics present in a test subject’s images. Marginal probability density functions of selected features are estimated through PCA models, in conjunction with an “estimability” criterion that limits the dimensionality of estimated probability densities according to available sample size and underlying anatomy variation. A test sample is iteratively projected to the subspaces of these marginals as determined by PCA models, and its trajectory delineates potential abnormalities. The method is applied to segmentation of various brain lesion types, and to simulated data on which superiority of the iterative method over straight PCA is demonstrated. PMID:24607564

Impact of volunteer-related and methodology-related factors on the reproducibility of brachial artery flow-mediated vasodilation: analysis of 672 individual repeated measurements.

PubMed

van Mil, Anke C C M; Greyling, Arno; Zock, Peter L; Geleijnse, Johanna M; Hopman, Maria T; Mensink, Ronald P; Reesink, Koen D; Green, Daniel J; Ghiadoni, Lorenzo; Thijssen, Dick H

2016-09-01

Brachial artery flow-mediated dilation (FMD) is a popular technique to examine endothelial function in humans. Identifying volunteer and methodological factors related to variation in FMD is important to improve measurement accuracy and applicability. Volunteer-related and methodology-related parameters were collected in 672 volunteers from eight affiliated centres worldwide who underwent repeated measures of FMD. All centres adopted contemporary expert-consensus guidelines for FMD assessment. After calculating the coefficient of variation (%) of the FMD for each individual, we constructed quartiles (n = 168 per quartile). Based on two regression models (volunteer-related factors and methodology-related factors), statistically significant components of these two models were added to a final regression model (calculated as β-coefficient and R). This allowed us to identify factors that independently contributed to the variation in FMD%. Median coefficient of variation was 17.5%, with healthy volunteers demonstrating a coefficient of variation 9.3%. Regression models revealed age (β = 0.248, P < 0.001), hypertension (β = 0.104, P < 0.001), dyslipidemia (β = 0.331, P < 0.001), time between measurements (β = 0.318, P < 0.001), lab experience (β = -0.133, P < 0.001) and baseline FMD% (β = 0.082, P < 0.05) as contributors to the coefficient of variation. After including all significant factors in the final model, we found that time between measurements, hypertension, baseline FMD% and lab experience with FMD independently predicted brachial artery variability (total R = 0.202). Although FMD% showed good reproducibility, larger variation was observed in conditions with longer time between measurements, hypertension, less experience and lower baseline FMD%. Accounting for these factors may improve FMD% variability.

MORPHOLOGICAL VARIATION IN HATCHLING AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM THREE FLORIDA LAKES

EPA Science Inventory

Morphological variation of 508 hatchling alligators from three lakes in north central Florida (Lakes Woodruff, Apopka, and Orange) was analyzed using multivariate statistics. Morphological variation was found among clutches as well as among lakes. Principal components analysis wa...

A model for the statistical description of analytical errors occurring in clinical chemical laboratories with time.

PubMed

Hyvärinen, A

1985-01-01

The main purpose of the present study was to describe the statistical behaviour of daily analytical errors in the dimensions of place and time, providing a statistical basis for realistic estimates of the analytical error, and hence allowing the importance of the error and the relative contributions of its different sources to be re-evaluated. The observation material consists of creatinine and glucose results for control sera measured in daily routine quality control in five laboratories for a period of one year. The observation data were processed and computed by means of an automated data processing system. Graphic representations of time series of daily observations, as well as their means and dispersion limits when grouped over various time intervals, were investigated. For partition of the total variation several two-way analyses of variance were done with laboratory and various time classifications as factors. Pooled sets of observations were tested for normality of distribution and for consistency of variances, and the distribution characteristics of error variation in different categories of place and time were compared. Errors were found from the time series to vary typically between days. Due to irregular fluctuations in general and particular seasonal effects in creatinine, stable estimates of means or of dispersions for errors in individual laboratories could not be easily obtained over short periods of time but only from data sets pooled over long intervals (preferably at least one year). Pooled estimates of proportions of intralaboratory variation were relatively low (less than 33%) when the variation was pooled within days. However, when the variation was pooled over longer intervals this proportion increased considerably, even to a maximum of 89-98% (95-98% in each method category) when an outlying laboratory in glucose was omitted, with a concomitant decrease in the interaction component (representing laboratory-dependent variation with time). This indicates that a substantial part of the variation comes from intralaboratory variation with time rather than from constant interlaboratory differences. Normality and consistency of statistical distributions were best achieved in the long-term intralaboratory sets of the data, under which conditions the statistical estimates of error variability were also most characteristic of the individual laboratories rather than necessarily being similar to one another. Mixing of data from different laboratories may give heterogeneous and nonparametric distributions and hence is not advisable.(ABSTRACT TRUNCATED AT 400 WORDS)

The 3C 279 Campaign of Winter 1999: A Gamma-Optical Correlation?

NASA Technical Reports Server (NTRS)

Hartman, R. C.; Villata, M.; Raiteri, C. M.; Sobrito, M.; DeFrancesco, G.; Ostorero, L.; Tosti, G.; Kurtanidze, O.; Nikolashvili, M.; Takalo, L.

2000-01-01

Preliminary results are presented from the gamma-optical campaign of January-February 1999 on 3C 279. During this period we obtained good optical sampling of the source, the best ever for a gamma-bright OVV quasar. Its large and fast variations have been compared with the gamma-ray fluxes obtained simultaneously by Energy Gamma Ray Experiment Telescope (EGRET), on Compton Gamma Ray Observatory (CGRO). Despite rather poor counting statistics in the gamma-ray data, a fair correlation is found, with the gamma variations following those in the optical by 3-4 days. This is the first time such a significant day-scale correlation has been observed between the optical and gamma emissions from a OVV quasar. Its implications are currently under study.

Genetics of Nicotine Dependence and Pharmacotherapy

PubMed Central

Lessov-Schlaggar, Christina N.; Pergadia, Michele L.; Khroyan, Taline V.; Swan, Gary E.

2008-01-01

Nicotine dependence is substantially heritable. Several regions across the genome have been implicated in containing genes that confer liability to nicotine dependence and variation in individual genes has been associated with nicotine dependence. Smoking cessation measures are also heritable, and measured genetic variation is associated with nicotine dependence treatment efficacy. Despite significant strides in the understanding of the relative contribution of genetic and environmental factors to nicotine dependence and treatment, emergent challenges necessitate interdisciplinary coordinated effort for effective problem solving. These challenges include refinement of the nicotine dependence phenotype, better understanding of the dynamic interplay between genes and environment in nicotine dependence etiology, application and development of molecular and statistical methodology that can adequately address vast amounts of data, and continuous translational cross-talk. PMID:17888884

Chronological, geographical, and seasonal trends of human cases of avian influenza A (H5N1) in Vietnam, 2003-2014: a spatial analysis.

PubMed

Manabe, Toshie; Yamaoka, Kazue; Tango, Toshiro; Binh, Nguyen Gia; Co, Dao Xuan; Tuan, Nguyen Dang; Izumi, Shinyu; Takasaki, Jin; Chau, Ngo Quy; Kudo, Koichiro

2016-02-04

Human cases of highly pathogenic avian influenza A (H5N1) virus infection continue to occur in Southeast Asia. The objective of this study was to identify when and where human H5N1 cases have occurred in Vietnam and how the situation has changed from the beginning of the H5N1 outbreaks in 2003 through 2014, to assist with implementing methods of targeted disease management. We assessed the disease clustering and seasonal variation of human H5N1 cases in Vietnam to evaluate the geographical and monthly timing trends. The clustering of H5N1 cases and associated mortality were examined over three time periods: the outbreak period (2003-2005), the post-outbreak (2006-2009), and the recent period (2010-2014) using the flexibly shaped space-time scan statistic. The most likely cases to co-cluster and the elevated risks for incidence and mortality were assessed via calculation of the relative risk (RR). The H5N1 case seasonal variation was analysed as the cyclic trend in incidence data using Roger's statistical test. Between 2003 and 2005, H5N1 cases (RR: 2.15, p = 0.001) and mortality (RR: 2.49, p = 0.021) were significantly clustered in northern Vietnam. After 2010, H5N1 cases tended to occur on the border with Cambodia in the south, while H5N1 mortality clustered significantly in the Mekong delta area (RR: 6.62, p = 0.002). A significant seasonal variation was observed (p < 0.001), with a higher incidence of morbidity in December through April. These findings indicate that clinical preparedness for H5N1 in Vietnam needs to be strengthened in southern Vietnam in December-April.

Interpreting locomotor biomechanics from the morphology of human footprints.

PubMed

Hatala, Kevin G; Wunderlich, Roshna E; Dingwall, Heather L; Richmond, Brian G

2016-01-01

Fossil hominin footprints offer unique direct windows to the locomotor behaviors of our ancestors. These data could allow a clearer understanding of the evolution of human locomotion by circumventing issues associated with indirect interpretations of habitual locomotor patterns from fossil skeletal material. However, before we can use fossil hominin footprints to understand better the evolution of human locomotion, we must first develop an understanding of how locomotor biomechanics are preserved in, and can be inferred from, footprint morphologies. In this experimental study, 41 habitually barefoot modern humans created footprints under controlled conditions in which variables related to locomotor biomechanics could be quantified. Measurements of regional topography (depth) were taken from 3D models of those footprints, and principal components analysis was used to identify orthogonal axes that described the largest proportions of topographic variance within the human experimental sample. Linear mixed effects models were used to quantify the influences of biomechanical variables on the first five principal axes of footprint topographic variation, thus providing new information on the biomechanical variables most evidently expressed in the morphology of human footprints. The footprint's overall depth was considered as a confounding variable, since biomechanics may be linked to the extent to which a substrate deforms. Three of five axes showed statistically significant relationships with variables related to both locomotor biomechanics and substrate displacement; one axis was influenced only by biomechanics and another only by the overall depth of the footprint. Principal axes of footprint morphological variation were significantly related to gait type (walking or running), kinematics of the hip and ankle joints and the distribution of pressure beneath the foot. These results provide the first quantitative framework for developing hypotheses regarding the biomechanical patterns reflected by fossil hominin footprints by demonstrating the statistically significant effects of specific kinematic variables on patterns of variation in footprint topography. Copyright © 2015 Elsevier Ltd. All rights reserved.

An evaluation of relation between the relative parallelism of occlusal plane to ala-tragal line and variation in the angulation of Po-Na-ANS angle in dentulous subjects: A cephalometric study

PubMed Central

Shetty, Sanath; Shenoy, K. Kamalakanth; Ninan, Justin; Mahaseth, Pranay

2015-01-01

Aims: The aim was to evaluate if any correlation exists between variation in angulation of Po-Na-ANS angle and relative parallelism of the occlusal plane to the different tragal levels of the ear in dentulous subjects. Methodology: A total of 200 subjects were selected for the study. A custom made occlusal plane analyzer was used to determine the posterior point of the ala-tragal line. The lateral cephalogram was shot for each of the subjects. The points Porion, Nasion, and Anterior Nasal Spine were located and the angle formed between these points was measured. Statistical Analysis Used: Fischer's exact test was used to find the correlation between Po-Na-ANS angle and relative parallelism of the occlusal plane to the ala-tragal line at different tragal levels. Results: Statistical analysis showed no significant correlation between Po-Na-ANS angle and relative parallelism of an occlusal plane at different tragal levels, and an inferior point on the tragus was the most common. Conclusion: Irrespective of variations in the Po-Na-ANS angle, no correlation exists between the variation in the angulations of Po-Na-ANS angle and the relative parallelism of occlusal plane to the ala-tragal line at different tragal levels. Furthermore, in a large number of subjects (54%), the occlusal plane was found parallel to a line joining the inferior border of the ala of the nose and the inferior part of the tragus. PMID:26929506

Effect of incubation temperature and time on the precision of data generated by antibiotic disc diffusion assays.

PubMed

Smith, P; Kronvall, G

2015-07-01

The influence on the precision of disc diffusion data of the conditions under which the tests were performed was examined by analysing multilaboratory data sets generated after incubation at 35 °C for 18 h, at 28 °C for 24 h and 22 °C for 24 h and 48 h. Analyses of these data sets demonstrated that precision was significantly and progressively decreased as the test temperature was reduced from 35 to 22 °C. Analysis of the data obtained at 22 °C also showed the precision was inversely related to the time of incubation. Temperature and time related decreases in precision were not related to differences in the mean zone sizes of the data sets obtained under these test conditions. Analysis of the zone data obtained at 28 and 22 °C as single laboratory sets demonstrated that reductions of incubation temperature resulted in significant increases in both intralaboratory and interlaboratory variation. Increases in incubation time at 22 °C were, however, associated with statistically significant increases in interlaboratory variation but not with any significant increase in intralaboratory variation. The significance of these observations for the establishment of the acceptable limits of precision of data sets that can be used for the setting of valid epidemiological cut-off values is discussed. © 2014 John Wiley & Sons Ltd.

Diurnal Variations in Global Joule Heating Morphology and Magnitude Due To Neutral Winds

NASA Astrophysics Data System (ADS)

Billett, D. D.; Grocott, A.; Wild, J. A.; Walach, M.-T.; Kosch, M. J.

2018-03-01

In the polar ionosphere, variations in Joule heating are significantly controlled by changes in plasma convection, such as that brought about by changes in the interplanetary magnetic field. However, another important consideration when calculating Joule heating is the velocity difference between this plasma and the neutral thermosphere colocated with the ionosphere. Neutral wind data are often difficult to obtain on a global scale; thus, Joule heating has often previously been calculated assuming that neutral velocities are small and can therefore be neglected. Previous work has shown the effect of neutral winds on Joule heating estimations to be more significant than originally thought; however, the diurnal variations of the neutrals due to changes in solar pressure gradients and Coriolis forces have yet to have their impact on Joule heating assessed. We show this universal time effect to be significant in calculating Joule heating and thus can differ significantly from that calculated by neglecting the neutrals. In this study, we use empirical models for the neutral wind, conductivities, and magnetic field to create Northern Hemispheric patterns of Joule heating for approximately 800,000 individual plasma convection patterns generated using data from the Super Dual Auroral Radar Network. From this, a statistical analysis of how Joule heating varies in morphology and magnitude with universal time is shown for differing seasons and levels of geomagnetic activity. We find that neutral winds do play a significant role in the morphology and total energy output of Joule heating.

Quantifying Variations in Airborne Gravity Data Quality Due to Aircraft Selection with the Gravity for the Re-Definition of the American Vertical Datum Project

NASA Astrophysics Data System (ADS)

Youngman, M.; Weil, C.; Salisbury, T.; Villarreal, C.

2015-12-01

The U.S. National Geodetic Survey is collecting airborne gravity with the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project to produce a geoid supporting heights accurate to 2 centimeters, where possible, with a modernized U.S. vertical datum in 2022. Targeting 15.6 million square kilometers, the GRAV-D project is unprecedented in its scope of consistently collected airborne gravity data across the entire U.S. and its holdings. Currently over 42% of data collection has been completed by 42 surveys (field campaigns) covering 34 completed blocks (data collection areas). The large amount of data available offers a unique opportunity to evaluate the causes of data quality variation from survey to survey. Two metrics were chosen to use as a basis for comparing the quality of each survey/block: 1. total crossover error (i.e. difference in gravity recorded at all locations of crossing flight lines) and 2. the statistical difference of the airborne gravity from the EGM2008 global model. We have determined that the aircraft used for surveying contributes significantly to the variation in data quality. This paper will further expand upon that recent work, using statistical analysis to determine the contribution of aircraft selection to data quality taking into account other variables such as differences in survey setup or weather conditions during surveying.

Random field assessment of nanoscopic inhomogeneity of bone.

PubMed

Dong, X Neil; Luo, Qing; Sparkman, Daniel M; Millwater, Harry R; Wang, Xiaodu

2010-12-01

Bone quality is significantly correlated with the inhomogeneous distribution of material and ultrastructural properties (e.g., modulus and mineralization) of the tissue. Current techniques for quantifying inhomogeneity consist of descriptive statistics such as mean, standard deviation and coefficient of variation. However, these parameters do not describe the spatial variations of bone properties. The objective of this study was to develop a novel statistical method to characterize and quantitatively describe the spatial variation of bone properties at ultrastructural levels. To do so, a random field defined by an exponential covariance function was used to represent the spatial uncertainty of elastic modulus by delineating the correlation of the modulus at different locations in bone lamellae. The correlation length, a characteristic parameter of the covariance function, was employed to estimate the fluctuation of the elastic modulus in the random field. Using this approach, two distribution maps of the elastic modulus within bone lamellae were generated using simulation and compared with those obtained experimentally by a combination of atomic force microscopy and nanoindentation techniques. The simulation-generated maps of elastic modulus were in close agreement with the experimental ones, thus validating the random field approach in defining the inhomogeneity of elastic modulus in lamellae of bone. Indeed, generation of such random fields will facilitate multi-scale modeling of bone in more pragmatic details. Copyright © 2010 Elsevier Inc. All rights reserved.

Algorithm for Identifying Erroneous Rain-Gauge Readings

NASA Technical Reports Server (NTRS)

Rickman, Doug

2005-01-01

An algorithm analyzes rain-gauge data to identify statistical outliers that could be deemed to be erroneous readings. Heretofore, analyses of this type have been performed in burdensome manual procedures that have involved subjective judgements. Sometimes, the analyses have included computational assistance for detecting values falling outside of arbitrary limits. The analyses have been performed without statistically valid knowledge of the spatial and temporal variations of precipitation within rain events. In contrast, the present algorithm makes it possible to automate such an analysis, makes the analysis objective, takes account of the spatial distribution of rain gauges in conjunction with the statistical nature of spatial variations in rainfall readings, and minimizes the use of arbitrary criteria. The algorithm implements an iterative process that involves nonparametric statistics.

Density Effects on Post-shock Turbulence Structure

NASA Astrophysics Data System (ADS)

Tian, Yifeng; Jaberi, Farhad; Livescu, Daniel; Li, Zhaorui; Michigan State University Collaboration; Los Alamos National Laboratory Collaboration; Texas A&M University-Corpus Christi Collaboration

2017-11-01

The effects of density variations due to mixture composition on post-shock turbulence structure are studied using turbulence-resolving shock-capturing simulations. This work extends the canonical Shock-Turbulence Interaction (STI) problem to involve significant variable density effects. The numerical method has been verified using a series of grid and LIA convergence tests, and is used to generate accurate post-shock turbulence data for a detailed flow study. Density effects on post-shock turbulent statistics are shown to be significant, leading to an increased amplification of turbulent kinetic energy (TKE). Eulerian and Lagrangian analyses show that the increase in the post-shock correlation between rotation and strain is weakened in the case with significant density variations (referred to as the ``multi-fluid'' case). Similar to previous single-fluid results and LIA predictions, the shock wave significantly changes the topology of the turbulent structures, exhibiting a symmetrization of the joint PDF of second and third invariant of the deviatoric part of velocity gradient tensor. In the multi-fluid case, this trend is more significant and mainly manifested in the heavy fluid regions. Lagrangian data are also used to study the evolution of turbulence structure away from the shock wave and assess the accuracy of Lagrangian dynamical models.

Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

PubMed

Kamal, Ghulam Mustafa; Wang, Xiaohua; Bin Yuan; Wang, Jie; Sun, Peng; Zhang, Xu; Liu, Maili

2016-09-01

Soy sauce a well known seasoning all over the world, especially in Asia, is available in global market in a wide range of types based on its purpose and the processing methods. Its composition varies with respect to the fermentation processes and addition of additives, preservatives and flavor enhancers. A comprehensive (1)H NMR based study regarding the metabonomic variations of soy sauce to differentiate among different types of soy sauce available on the global market has been limited due to the complexity of the mixture. In present study, (13)C NMR spectroscopy coupled with multivariate statistical data analysis like principle component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) was applied to investigate metabonomic variations among different types of soy sauce, namely super light, super dark, red cooking and mushroom soy sauce. The main additives in soy sauce like glutamate, sucrose and glucose were easily distinguished and quantified using (13)C NMR spectroscopy which were otherwise difficult to be assigned and quantified due to serious signal overlaps in (1)H NMR spectra. The significantly higher concentration of sucrose in dark, red cooking and mushroom flavored soy sauce can directly be linked to the addition of caramel in soy sauce. Similarly, significantly higher level of glutamate in super light as compared to super dark and mushroom flavored soy sauce may come from the addition of monosodium glutamate. The study highlights the potentiality of (13)C NMR based metabonomics coupled with multivariate statistical data analysis in differentiating between the types of soy sauce on the basis of level of additives, raw materials and fermentation procedures. Copyright © 2016 Elsevier B.V. All rights reserved.

Validating Variational Bayes Linear Regression Method With Multi-Central Datasets.

PubMed

Murata, Hiroshi; Zangwill, Linda M; Fujino, Yuri; Matsuura, Masato; Miki, Atsuya; Hirasawa, Kazunori; Tanito, Masaki; Mizoue, Shiro; Mori, Kazuhiko; Suzuki, Katsuyoshi; Yamashita, Takehiro; Kashiwagi, Kenji; Shoji, Nobuyuki; Asaoka, Ryo

2018-04-01

To validate the prediction accuracy of variational Bayes linear regression (VBLR) with two datasets external to the training dataset. The training dataset consisted of 7268 eyes of 4278 subjects from the University of Tokyo Hospital. The Japanese Archive of Multicentral Databases in Glaucoma (JAMDIG) dataset consisted of 271 eyes of 177 patients, and the Diagnostic Innovations in Glaucoma Study (DIGS) dataset includes 248 eyes of 173 patients, which were used for validation. Prediction accuracy was compared between the VBLR and ordinary least squared linear regression (OLSLR). First, OLSLR and VBLR were carried out using total deviation (TD) values at each of the 52 test points from the second to fourth visual fields (VFs) (VF2-4) to 2nd to 10th VF (VF2-10) of each patient in JAMDIG and DIGS datasets, and the TD values of the 11th VF test were predicted every time. The predictive accuracy of each method was compared through the root mean squared error (RMSE) statistic. OLSLR RMSEs with the JAMDIG and DIGS datasets were between 31 and 4.3 dB, and between 19.5 and 3.9 dB. On the other hand, VBLR RMSEs with JAMDIG and DIGS datasets were between 5.0 and 3.7, and between 4.6 and 3.6 dB. There was statistically significant difference between VBLR and OLSLR for both datasets at every series (VF2-4 to VF2-10) (P < 0.01 for all tests). However, there was no statistically significant difference in VBLR RMSEs between JAMDIG and DIGS datasets at any series of VFs (VF2-2 to VF2-10) (P > 0.05). VBLR outperformed OLSLR to predict future VF progression, and the VBLR has a potential to be a helpful tool at clinical settings.

[The analysis of the polymorphic variations of the dopamine gen transporter (DAT1) and the serotonin transporter (5-HTTLPR) in patients with alcohol dependence syndrome with inclusion of the phenotypic feature of sweet liking preference].

PubMed

Jasiewicz, Andrzej; Grzywacz, Anna; Jabłoński, Marcin; Bieńkowski, Przemysław; Samochowiec, Agnieszka; Samochowiec, Jerzy

2014-01-01

The purpose of this study was to determine the relationship between sweet-liking phenotype and the variation of the gene sequence of the dopaminergic and serotonergic system. The study recruited 100 probands. The participants were interviewed for addiction (SSAGA-Semi Structured Assessment for the Genetics of Alcoholism) and assessed with the questionnaires: MMSE, Beck Depression Inventory and Hamilton Anxiety, Snaith-Hamilton Pleasure Scale. The taste was analyzed with tests to assess sensitivity to sweet taste and also smell tests were performed. Patients preferring the highest glucose volumes were called sweet likers. Statistical analyses were performed (SPSS- Statistical Package for the Social Sciences). Links between sweet liking phenotype and polymorphic variant of DAT1 gene were determined. The presence of DAT1 9/10 genotype increased three fold time sweet liking phenotype (p = 0.015, odds ratio-3.00), the presence of DAT1 10/10 decreased two fold time the chance being sweet liker (p = 0.051, odds ratio-0.43). Genotype 10/10 was significantly more common among sweet dislikers 10/10 (68.18% vs 47.92%) i 9/9 (6.82% vs 2.08%). CONCLUSIONS; A genetically significant association between the presence of 9/10 DAT1 VNTR genotype and a sweet-liking phenotype in probands was determined.

Daily variations in effluent water turbidity and diarrhoeal illness in a Russian city.

PubMed

Egorov, Andrey I; Naumova, Elena N; Tereschenko, Andrey A; Kislitsin, Victor A; Ford, Timothy E

2003-03-01

To assess an association between temporal variations in drinking water quality and gastrointestinal (GI) illness, a cohort study involving 100 randomly selected families (367 individuals) was conducted in the city of Cherepovets, Russia from June through November 1999. Participants maintained daily diaries of gastrointestinal symptoms, water consumption and other behavioural exposure variables, while daily effluent water quality data were provided by the water utility. The cumulative incidence rate of self-reported gastrointestinal diseases, 1.7 cases per person-year, was almost two orders of magnitude higher than that of officially reported GI infections in the city. An interquartile range increase in effluent water turbidity of 0.8 Nephelometric Turbidity Units was associated with a relative risk of self-reported GI illness of 1.47 (95% Confidence Interval 1.16, 1.86) at a lag of 2 days after control for daily rate of consumption of non-boiled tap water, behavioural covariates, day of the week and a seasonally-related linear trend. In the analysis by subsets of study participants stratified by non-boiled tap water consumption, no statistically significant associations between turbidity and GI illness were found for the study participants who always boiled their drinking water. For individuals who drank non-boiled tap water, statistically significant associations between turbidity and GI illness were detected at lags 1, 2 and 7 days.

[Effect of repeated sintering and variations in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers].

PubMed

Cui, Huang; Jia, Yu; Shaofeng, Meng; Biyun, Gao

2017-08-01

Objective The aim of this study is to evaluate the effect of repeated sintering and variation in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers. Methods A total of 24 computer aided design and computer aided manufacturing (CAD/CAM) veneers was fabricated using the IPS e.max-CAD LS2 and then randomly divided into four groups (S0, S1, S2, S3; n=6). Each group was sintered 0, 1, 2, 3 times individually according to the manufacturer's recommendation. The color parameters (L, C, H, a, b values) of all the specimens were measured by a Vita easyshade dental colorimeter. The results were statistically analyzed using the SAS 9.1.3 software for MANOVA and LSD. Subsequently, the microstructures of the intersecting surfaces of the specimens were observed by scanning electron microscopy (SEM). Results After repeated sintering, the L value significantly decreased (P<0.05). For the C and b values, statistical differences were observed among the groups except between S2 and S3. SEM results showed that the interlocking microstructures of rod-shaped Li₂Si₂O₅ crystals became more compact when the number of sintering times was increased. Conclusion Repeated sintering exhibited significant influence on the color of the IPS e.max-CAD LS2 veneers.

Micro-organisms behind the pollination scenes: microbial imprint on floral nectar sugar variation in a tropical plant community.

PubMed

Canto, A; Herrera, C M

2012-11-01

Variation in the composition of floral nectar reflects intrinsic plant characteristics as well as the action of extrinsic factors. Micro-organisms, particularly yeasts, represent one extrinsic factor that inhabit the nectar of animal-pollinated flowers worldwide. In this study a 'microbial imprint hypothesis' is formulated and tested, in which it is proposed that natural community-wide variation in nectar sugar composition will partly depend on the presence of yeasts in flowers. Occurrence and density of yeasts were studied microscopically in single-flower nectar samples of 22 animal-pollinated species from coastal xeric and sub-humid tropical habitats of the Yucatán Peninsula, Mexico. Nectar sugar concentration and composition were concurrently determined on the same samples using high-performance liquid chromatography (HPLC) methods. Microscopical examination of nectar samples revealed the presence of yeasts in nearly all plant species (21 out of 22 species) and in about half of the samples examined (51·8 % of total, all species combined). Plant species and individuals differed significantly in nectar sugar concentration and composition, and also in the incidence of nectar yeasts. After statistically controlling for differences between plant species and individuals, nectar yeasts still accounted for a significant fraction of community-wide variance in all nectar sugar parameters considered. Significant yeast × species interactions on sugar parameters revealed that plant species differed in the nectar sugar correlates of variation in yeast incidence. The results support the hypothesis that nectar yeasts impose a detectable imprint on community-wide variation in nectar sugar composition and concentration. Since nectar sugar features influence pollinator attraction and plant reproduction, future nectar studies should control for yeast presence and examine the extent to which microbial signatures on nectar characteristics ultimately have some influence on pollination services in plant communities.

Epigenetic variation predicts regional and local intraspecific functional diversity in a perennial herb.

PubMed

Medrano, Mónica; Herrera, Carlos M; Bazaga, Pilar

2014-10-01

The ecological significance of epigenetic variation has been generally inferred from studies on model plants under artificial conditions, but the importance of epigenetic differences between individuals as a source of intraspecific diversity in natural plant populations remains essentially unknown. This study investigates the relationship between epigenetic variation and functional plant diversity by conducting epigenetic (methylation-sensitive amplified fragment length polymorphisms, MSAP) and genetic (amplified fragment length polymorphisms, AFLP) marker-trait association analyses for 20 whole-plant, leaf and regenerative functional traits in a large sample of wild-growing plants of the perennial herb Helleborus foetidus from ten sampling sites in south-eastern Spain. Plants differed widely in functional characteristics, and exhibited greater epigenetic than genetic diversity, as shown by per cent polymorphism of MSAP fragments (92%) or markers (69%) greatly exceeding that for AFLP ones (41%). After controlling for genetic structuring and possible cryptic relatedness, every functional trait considered exhibited a significant association with at least one AFLP or MSAP marker. A total of 27 MSAP (13.0% of total) and 12 AFLP (4.4%) markers were involved in significant associations, which explained on average 8.2% and 8.0% of trait variance, respectively. Individual MSAP markers were more likely to be associated with functional traits than AFLP markers. Between-site differences in multivariate functional diversity were directly related to variation in multilocus epigenetic diversity after multilocus genetic diversity was statistically accounted for. Results suggest that epigenetic variation can be an important source of intraspecific functional diversity in H. foetidus, possibly endowing this species with the capacity to exploit a broad range of ecological conditions despite its modest genetic diversity. © 2014 John Wiley & Sons Ltd.

[Diurnal variation characteristics of leaf water potential of Spinifex littoreus on the nebkhas in different succession periods on the coast of Pingtan Island, Fujian Province, China.

PubMed

Yang, Xian Ji; Du, Jian Hui; Qin, Jing; Chen, Zhi Hua; Yang, Lin; Song, Shuang

2017-10-01

Diurnal variation and its influencing factors of leaf water potential (ψ l ) of Spinifex littoreus on the nebkhas in two succession periods were measured on the coast of Pingtan Island, Fujian Province. The results showed that the diurnal variation of ψ l of S. littoreus mainly demonstrated a 'W' curve pattern, with a temporary rise at midday. The mean ψ l of S. littoreus on the nebkhas at developing stage was higher than that at stabilizing stage, and recovered better during the night. ψ l of S. littoreus was positively related to the atmospheric water potential (ψ a ) and relative humidity, negatively related to air temperature, but had no significant correlation with the soil water potential at different depthes. ψ l of S. littoreus on the interdune depression at developing stage was higher than that on the windward slope and on the leeward slope from 10:00 to 16:00, and that on the windward slope was lower than that on the leeward slope all day long except at 10:00 and at 12:00. The variation of ψ l of S. littoreus on the leeward slope was higher than that on the windward slope, and the minimal variation was found on the interdune depression, without statistical significance. ψ l of S. littoreus on the windward slope was positively correlated with ψ a and relative humidity, while negatively correlated with air temperature. ψ l of S. littoreus on the leeward slope and the interdune depression were correlated with meteorological factors, but they had no significant relationship.

Analysis of sugars and pH in commercially available soft drinks in Saudi Arabia with a brief review on their dental implications.

PubMed

Idris, Ali Mohamed; Vani, Nandimandalam Venkata; Almutari, Dhafi A; Jafar, Mohammed A; Boreak, Nezar

2016-12-01

To determine the amount of sugar and pH in commercially available soft drinks in Jazan, Saudi Arabia. This was further compared with their labeled values in order to inform the regulations. The effects of these drinks on teeth is reviewed. Ten brands of popular soft drinks including 6 regular carbonated drinks and 4 energy drinks were obtained from the local markets. Their pH was determined using a pH meter. The amount of total sugar, glucose, fructose, and sucrose was estimated using high performance liquid chromatography (using Dionex ICS 5000 ion chromatography) at the Saudi Food and Drug Authority. Descriptive statistics was done to obtain the mean and standard deviation. Intergroup comparison was performed using independent t -test, and the labeled and estimated values within the group were compared with paired t -test. The labeled and estimated sugar in energy drinks (14.3 ± 0.48 and 15.6 ± 2.3, respectively) were higher than the carbonated drinks (11.2 ± 0.46 and 12.8 ± 0.99), which was statistically significant. In addition, there was a significant difference in the concentration of glucose in energy drinks (5.7 ± 1.7) compared to carbonated drinks (4.1 ± 1.4). The pH of these drinks ranged from 2.4 to 3.2. The differences between the estimated and labeled sugar in carbonated drinks showed statistical significance. Mild variation was observed in total sugar, glucose, fructose, and sucrose levels among different bottles of the same brand of these drinks. The low pH and high sugar content in these drinks are detrimental to dental health. Comparison of the estimated sugar with their labeled values showed variation in most of the brands. Preventive strategies should be implemented to reduce the health risks posed by these soft drinks.

Analysis of sugars and pH in commercially available soft drinks in Saudi Arabia with a brief review on their dental implications

PubMed Central

Idris, Ali Mohamed; Vani, Nandimandalam Venkata; Almutari, Dhafi A.; Jafar, Mohammed A.; Boreak, Nezar

2016-01-01

Objective: To determine the amount of sugar and pH in commercially available soft drinks in Jazan, Saudi Arabia. This was further compared with their labeled values in order to inform the regulations. The effects of these drinks on teeth is reviewed. Materials and Methods: Ten brands of popular soft drinks including 6 regular carbonated drinks and 4 energy drinks were obtained from the local markets. Their pH was determined using a pH meter. The amount of total sugar, glucose, fructose, and sucrose was estimated using high performance liquid chromatography (using Dionex ICS 5000 ion chromatography) at the Saudi Food and Drug Authority. Descriptive statistics was done to obtain the mean and standard deviation. Intergroup comparison was performed using independent t-test, and the labeled and estimated values within the group were compared with paired t-test. Results: The labeled and estimated sugar in energy drinks (14.3 ± 0.48 and 15.6 ± 2.3, respectively) were higher than the carbonated drinks (11.2 ± 0.46 and 12.8 ± 0.99), which was statistically significant. In addition, there was a significant difference in the concentration of glucose in energy drinks (5.7 ± 1.7) compared to carbonated drinks (4.1 ± 1.4). The pH of these drinks ranged from 2.4 to 3.2. The differences between the estimated and labeled sugar in carbonated drinks showed statistical significance. Mild variation was observed in total sugar, glucose, fructose, and sucrose levels among different bottles of the same brand of these drinks. Conclusion: The low pH and high sugar content in these drinks are detrimental to dental health. Comparison of the estimated sugar with their labeled values showed variation in most of the brands. Preventive strategies should be implemented to reduce the health risks posed by these soft drinks. PMID:28217536

Optical properties of mice skin for optical therapy relevant wavelengths: influence of gender and pigmentation

NASA Astrophysics Data System (ADS)

Sabino, C. P.; Deana, A. M.; Silva, D. F. T.; França, C. M.; Yoshimura, T. M.; Ribeiro, M. S.

2015-03-01

Red and near-infrared light have been widely employed in optical therapies. Skin is the most common optical barrier in non-invasive techniques and in many cases it is the target tissue itself. Consequently, to optimize the outcomes brought by lightbased therapies, the optical properties of skin tissue must be very well elucidated. In the present study, we evaluated the dorsal skin optical properties of albino (BALB/c) and pigmented (C57BL/6) mice using the Kubelka-Munk photon transport model. We evaluated samples from male and female young mice of both strains. Analysis was performed for wavelengths at 630, 660, 780, 810 and 905 nm due to their prevalent use in optical therapies, such as low-level light (or laser) and photodynamic therapies. Spectrophotometric measurements of diffuse transmittance and reflectance were performed using a single integrating sphere coupled to a proper spectrophotometer. Statistic analysis was made by two-way ANOVA, with Tukey as post-test and Levenne and Shapiro-Wilks as pre-tests. Statistical significance was considered when p<0.05. Our results show only a slight transmittance increment (<10 %) as wavelengths are increased from 630 to 905 nm, and no statistical significance was observed. Albino male mice present reduced transmittance levels for all wavelengths. The organization and abundance of skin composing tissues significantly influence its scattering optical properties although absorption remains constant. We conclude that factors such as subcutaneous adiposity and connective tissue structure can have statistically significant influence on mice skin optical properties and these factors have relevant variations among different gender and strains.

Statistical investigation of simulated intestinal fluid composition on the equilibrium solubility of biopharmaceutics classification system class II drugs.

PubMed

Khadra, Ibrahim; Zhou, Zhou; Dunn, Claire; Wilson, Clive G; Halbert, Gavin

2015-01-25

A drug's solubility and dissolution behaviour within the gastrointestinal tract is a key property for successful administration by the oral route and one of the key factors in the biopharmaceutics classification system. This property can be determined by investigating drug solubility in human intestinal fluid (HIF) but this is difficult to obtain and highly variable, which has led to the development of multiple simulated intestinal fluid (SIF) recipes. Using a statistical design of experiment (DoE) technique this paper has investigated the effects and interactions on equilibrium drug solubility of seven typical SIF components (sodium taurocholate, lecithin, sodium phosphate, sodium chloride, pH, pancreatin and sodium oleate) within concentration ranges relevant to human intestinal fluid values. A range of poorly soluble drugs with acidic (naproxen, indomethacin, phenytoin, and piroxicam), basic (aprepitant, carvedilol, zafirlukast, tadalafil) or neutral (fenofibrate, griseofulvin, felodipine and probucol) properties have been investigated. The equilibrium solubility results determined are comparable with literature studies of the drugs in either HIF or SIF indicating that the DoE is operating in the correct space. With the exception of pancreatin, all of the factors individually had a statistically significant influence on equilibrium solubility with variations in magnitude of effect between the acidic and basic or neutral compounds and drug specific interactions were evident. Interestingly for the neutral compounds pH was the factor with the second largest solubility effect. Around one third of all the possible factor combinations showed a significant influence on equilibrium solubility with variations in interaction significance and magnitude of effect between the acidic and basic or neutral compounds. The least number of significant media component interactions were noted for the acidic compounds with three and the greatest for the neutral compounds at seven, with again drug specific effects evident. This indicates that a drug's equilibrium solubility in SIF is influenced depending upon drug type by between eight to fourteen individual or combinations of media components with some of these drug specific. This illustrates the complex nature of these fluids and provides for individual drugs a visualisation of the possible solubility envelope within the gastrointestinal tract, which may be of importance for modelling in vivo behaviour. In addition the results indicate that the design of experiment approach can be employed to provide greater detail of drug solubility behaviour, possible drug specific interactions and influence of variations in gastrointestinal media components due to disease. The approach is also feasible and amenable to adaptation for high throughput screening of drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

Refining the Use of Linkage Disequilibrium as a Robust Signature of Selective Sweeps

PubMed Central

Jacobs, Guy S.; Sluckin, Timothy J.; Kivisild, Toomas

2016-01-01

During a selective sweep, characteristic patterns of linkage disequilibrium can arise in the genomic region surrounding a selected locus. These have been used to infer past selective sweeps. However, the recombination rate is known to vary substantially along the genome for many species. We here investigate the effectiveness of current (Kelly’s ZnS and ωmax) and novel statistics at inferring hard selective sweeps based on linkage disequilibrium distortions under different conditions, including a human-realistic demographic model and recombination rate variation. When the recombination rate is constant, Kelly’s ZnS offers high power, but is outperformed by a novel statistic that we test, which we call Zα. We also find this statistic to be effective at detecting sweeps from standing variation. When recombination rate fluctuations are included, there is a considerable reduction in power for all linkage disequilibrium-based statistics. However, this can largely be reversed by appropriately controlling for expected linkage disequilibrium using a genetic map. To further test these different methods, we perform selection scans on well-characterized HapMap data, finding that all three statistics—ωmax, Kelly’s ZnS, and Zα—are able to replicate signals at regions previously identified as selection candidates based on population differentiation or the site frequency spectrum. While ωmax replicates most candidates when recombination map data are not available, the ZnS and Zα statistics are more successful when recombination rate variation is controlled for. Given both this and their higher power in simulations of selective sweeps, these statistics are preferred when information on local recombination rate variation is available. PMID:27516617

THE MAGNETIC CLASSIFICATION OF SOLAR ACTIVE REGIONS 1992–2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaeggli, S. A.; Norton, A. A., E-mail: sarah.jaeggli@nasa.gov

The purpose of this Letter is to address a blindspot in our knowledge of solar active region (AR) statistics. To the best of our knowledge, there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all ARs reported in the daily Solar Region Summary from 1992 January 1 to 2015 December 31. We find that the α and β class ARs (including all sub-groups, e.g., βγ, βδ) make up fractions of approximately 20% and 80% of the sample, respectively. This fraction ismore » relatively constant during high levels of activity; however, an increase in the α fraction to about 35% and and a decrease in the β fraction to about 65% can be seen near each solar minimum and are statistically significant at the 2σ level. Over 30% of all ARs observed during the years of solar maxima were appended with the classifications γ and/or δ, while these classifications account for only a fraction of a percent during the years near the solar minima. This variation in the AR types indicates that the formation of complex ARs may be due to the pileup of frequent emergence of magnetic flux during solar maximum, rather than the emergence of complex, monolithic flux structures.« less

4P: fast computing of population genetics statistics from large DNA polymorphism panels

PubMed Central

Benazzo, Andrea; Panziera, Alex; Bertorelle, Giorgio

2015-01-01

Massive DNA sequencing has significantly increased the amount of data available for population genetics and molecular ecology studies. However, the parallel computation of simple statistics within and between populations from large panels of polymorphic sites is not yet available, making the exploratory analyses of a set or subset of data a very laborious task. Here, we present 4P (parallel processing of polymorphism panels), a stand-alone software program for the rapid computation of genetic variation statistics (including the joint frequency spectrum) from millions of DNA variants in multiple individuals and multiple populations. It handles a standard input file format commonly used to store DNA variation from empirical or simulation experiments. The computational performance of 4P was evaluated using large SNP (single nucleotide polymorphism) datasets from human genomes or obtained by simulations. 4P was faster or much faster than other comparable programs, and the impact of parallel computing using multicore computers or servers was evident. 4P is a useful tool for biologists who need a simple and rapid computer program to run exploratory population genetics analyses in large panels of genomic data. It is also particularly suitable to analyze multiple data sets produced in simulation studies. Unix, Windows, and MacOs versions are provided, as well as the source code for easier pipeline implementations. PMID:25628874

Statistical analysis of the electrocatalytic activity of Pt nanoparticles supported on novel functionalized reduced graphene oxide-chitosan for methanol electrooxidation

NASA Astrophysics Data System (ADS)

Ekrami-Kakhki, Mehri-Saddat; Abbasi, Sedigheh; Farzaneh, Nahid

2018-01-01

The purpose of this study is to statistically analyze the anodic current density and peak potential of methanol oxidation at Pt nanoparticles supported on functionalized reduced graphene oxide (RGO), using design of experiments methodology. RGO is functionalized with methyl viologen (MV) and chitosan (CH). The novel Pt/MV-RGO-CH catalyst is successfully prepared and characterized with transmission electron microscopy (TEM) image. The electrocatalytic activity of Pt/MV-RGOCH catalyst is experimentally evaluated for methanol oxidation. The effects of methanol concentration and scan rate factors are also investigated experimentally and statistically. The effects of these two main factors and their interactions are investigated, using analysis of variance test, Duncan's multiple range test and response surface method. The results of the analysis of variance show that all the main factors and their interactions have a significant effect on anodic current density and peak potential of methanol oxidation at α = 0.05. The suggested models which encompass significant factors can predict the variation of the anodic current density and peak potential of methanol oxidation. The results of Duncan's multiple range test confirmed that there is a significant difference between the studied levels of the main factors. [Figure not available: see fulltext.

Variations in Eyeball Diameters of the Healthy Adults

PubMed Central

Bekerman, Inessa; Gottlieb, Paul

2014-01-01

The purpose of the current research was to reevaluate the normative data on the eyeball diameters. Methods. In a prospective cohort study, the CT data of consecutive 250 adults with healthy eyes were collected and analyzed, and sagittal, transverse, and axial diameters of both eyeballs were measured. The data obtained from the left eye and from the right eye were compared. The correlation analysis was performed with the following variables: orbit size, gender, age, and ethnic background. Results. We did not find statistically significant differences correlated with gender of the patients and their age. The right eyeball was slightly smaller than the left one but this difference was statistically insignificant (P = 0.17). We did not find statistically significant differences of the eyeball sizes among the ethnicities we dealt with. Strong correlation was found between the transverse diameter and the width of the orbit (r = 0.88). Conclusion. The size of a human adult eye is approximately 24.2 mm (transverse) × 23.7 mm (sagittal) × 22.0–24.8 mm (axial) with no significant difference between sexes and age groups. In the transverse diameter, the eyeball size may vary from 21 mm to 27 mm. These data might be useful in ophthalmological, oculoplastic, and neurological practice. PMID:25431659

Variations in eyeball diameters of the healthy adults.

PubMed

Bekerman, Inessa; Gottlieb, Paul; Vaiman, Michael

2014-01-01

The purpose of the current research was to reevaluate the normative data on the eyeball diameters. Methods. In a prospective cohort study, the CT data of consecutive 250 adults with healthy eyes were collected and analyzed, and sagittal, transverse, and axial diameters of both eyeballs were measured. The data obtained from the left eye and from the right eye were compared. The correlation analysis was performed with the following variables: orbit size, gender, age, and ethnic background. Results. We did not find statistically significant differences correlated with gender of the patients and their age. The right eyeball was slightly smaller than the left one but this difference was statistically insignificant (P = 0.17). We did not find statistically significant differences of the eyeball sizes among the ethnicities we dealt with. Strong correlation was found between the transverse diameter and the width of the orbit (r = 0.88). Conclusion. The size of a human adult eye is approximately 24.2 mm (transverse) × 23.7 mm (sagittal) × 22.0-24.8 mm (axial) with no significant difference between sexes and age groups. In the transverse diameter, the eyeball size may vary from 21 mm to 27 mm. These data might be useful in ophthalmological, oculoplastic, and neurological practice.

Subjective evaluation of compressed image quality

NASA Astrophysics Data System (ADS)

Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

1992-05-01

Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

Migration and common mental disorder: an improvement in mental health over time?

PubMed

Butler, Margaret; Warfa, Nasir; Khatib, Yasmin; Bhui, Kamaldeep

2015-02-01

Global migration is reaching record high levels and UK migrant groups comprise an increasing proportion of the total population. The migratory process causes stress that can affect mental health. There is limited consistent empirical evidence of a longitudinal nature to explain the association between migration and mental health. This review aims to examine the evidence of a relationship between migration and common mental disorder (CMD) amongst migrants over time. A comprehensive search of medical and psychiatric databases for global quantitative empirical studies investigating incidence of CMD amongst adult migrants from 1975 to July 2012 was conducted. Declines in rates of CMD amongst migrants over time were reported by two thirds of the 18 studies reviewed, less than one third of which were statistically significant. On the contrary, three studies showed an increased rate of CMD, one statistically significant. Individual psychological resources, social support, the acculturation process, cultural variations and time since relocation are identified as statistically significant protective factors against the development of CMD amongst migrants. New enlightening points include the significant impact of varying patterns of psychological distress, of which negative is the most adverse for CMD. Migration is an extremely complex process. Further clarification is needed to gain deeper understanding of the relationship between migration and CMD to address contradictions in the literature and health inequalities amongst migrants.

Privacy-Preserving Data Exploration in Genome-Wide Association Studies.

PubMed

Johnson, Aaron; Shmatikov, Vitaly

2013-08-01

Genome-wide association studies (GWAS) have become a popular method for analyzing sets of DNA sequences in order to discover the genetic basis of disease. Unfortunately, statistics published as the result of GWAS can be used to identify individuals participating in the study. To prevent privacy breaches, even previously published results have been removed from public databases, impeding researchers' access to the data and hindering collaborative research. Existing techniques for privacy-preserving GWAS focus on answering specific questions, such as correlations between a given pair of SNPs (DNA sequence variations). This does not fit the typical GWAS process, where the analyst may not know in advance which SNPs to consider and which statistical tests to use, how many SNPs are significant for a given dataset, etc. We present a set of practical, privacy-preserving data mining algorithms for GWAS datasets. Our framework supports exploratory data analysis, where the analyst does not know a priori how many and which SNPs to consider. We develop privacy-preserving algorithms for computing the number and location of SNPs that are significantly associated with the disease, the significance of any statistical test between a given SNP and the disease, any measure of correlation between SNPs, and the block structure of correlations. We evaluate our algorithms on real-world datasets and demonstrate that they produce significantly more accurate results than prior techniques while guaranteeing differential privacy.

Across the Great Divide: The Effects of Technology in Secondary Biology Classrooms

NASA Astrophysics Data System (ADS)

Worley, Johnny Howard, II

This study investigates the relationship between technology use and student achievement in public high school across North Carolina. The purpose of this study was to determine whether a digital divide (differences in technology utilization based on student demographics of race/ethnicity, gender, socioeconomic status, and municipality) exists among schools and whether those differences relate to student achievement in high school biology classrooms. The study uses North Carolina end-of-course (EOC) data for biology to analyze student demographic data and assessment results from the 2010-2011 school year from the North Carolina Department of Public Instruction. The data analyses use descriptive and factorial univariate statistics to determine the existence of digital divides and their effects on biology achievement. Analysis of these data described patterns of technology use to determine whether potential variances resulted in a digital divide. Specific technology uses were identified in the data and then their impact on biology achievement scores within various demographic groups was examined. Research findings revealed statistically significant variations of use within different population groups. Despite being statistically significant, the relevance of the association in the variations was minimal at best -- based on the effect scale established by Cohen (1988). Additional factorial univariate analyses were employed to determine potential relationships between technology use and student achievement. The data revealed that technology use did not influence the variation of student achievement scale scores as much as race/ethnicity and socioeconomic status. White students outperformed Hispanic students by an average of three scale score points and Black students by an average of six scale score points. Technology use alone averaged less than a one point difference in mean scale scores, and only when interacting with race, gender, and/or SES did the mean difference increase. However, this increase within the context of the biology scale score range was negligible. This study contributes to the existing body of research on the effects of technology use on student achievement and its influence within various student demographic groups and municipalities. The study also provides additional research information for effective technology utilization, implementation, and instruction in educational environments.

Robust non-Gaussian statistics and long-range correlation of total ozone

NASA Astrophysics Data System (ADS)

Toumi, R.; Syroka, J.; Barnes, C.; Lewis, P.

2001-01-01

Three long-term total ozone time series at Camborne, Lerwick and Arosa are examined for their statistical properties. Non-Gaussian behaviour is seen for all locations. There are large interannual fluctuations in the higher moments of the probability distribution. However, only the mean for all stations and summer standard deviation at Lerwick show significant trends. This suggests that there has been no long-term change in the stratospheric circulation, but there are decadal variations. The time series can be also characterised as scale invariant with a Hurst exponent of about 0.8 for all three sites. The Arosa time series was found to be weakly intermittent, in agreement with the non-Gaussian characteristics of the data set

Efficient identification of context dependent subgroups of risk from genome wide association studies

PubMed Central

Dyson, Greg; Sing, Charles F.

2014-01-01

We have developed a modified Patient Rule-Induction Method (PRIM) as an alternative strategy for analyzing representative samples of non-experimental human data to estimate and test the role of genomic variations as predictors of disease risk in etiologically heterogeneous sub-samples. A computational limit of the proposed strategy is encountered when the number of genomic variations (predictor variables) under study is large (> 500) because permutations are used to generate a null distribution to test the significance of a term (defined by values of particular variables) that characterizes a sub-sample of individuals through the peeling and pasting processes. As an alternative, in this paper we introduce a theoretical strategy that facilitates the quick calculation of Type I and Type II errors in the evaluation of terms in the peeling and pasting processes carried out in the execution of a PRIM analysis that are underestimated and non-existent, respectively, when a permutation-based hypothesis test is employed. The resultant savings in computational time makes possible the consideration of larger numbers of genomic variations (an example genome wide association study is given) in the selection of statistically significant terms in the formulation of PRIM prediction models. PMID:24570412

[Multilevel model analysis on the relevant factors influencing the total amount of drinking water consumed daily by Beijing residents].

PubMed

Zhao, Jinhui; Wei, Jianrong; Chen, Huajie; Liu, Yumin; Li, Tiantian; Sun, Qinghua; Liu, Qiaolan

2012-09-01

To investigate the influencing factors for daily water intake of Beijing residents. A multi-stage sampling method was constructed to interview 270 Beijing residents in the winter of 2009 and in the summer of 2010 by using a questionnaire to collect data on daily drinking water consumption. Multilevel models were used to analyze the variation and influencing factors for the amount of water intake. Multilevel model results showed that the average daily water intake of residents living in different villages or neighborhood committees was statistically significant (sigma2 mu0 = = 0.030 (0.009), P < 0.05). The individual variation in the same village or neighborhood committee was also significant (sigma2 e0 = 0.157 (0.010), P < 0.05). Season, gender, and body weight affected the daily water intake (P < 0.05). There were interaction between season and source of water supply. The average daily water intake of residents was affected by several factors. In the health risk assessment of drinking water, it needs considering not only the individual characteristics but also the differences of villages/neighborhood committees and the seasonal variation.

INTERNAL ROOT MORPHOLOGY IN MANDIBULAR FIRST PERMANENT MOLARS IN A KENYAN POPULATION.

PubMed

Muriithi, N J; Maina, S W; Okoth, J; Gathece, L W

2012-05-01

To determine the internal root morphology and gender variations in mandibular first permanent molars in a Kenyan population. In vitro descriptive cross sectional study. School of Dental Sciences, University of Nairobi The mesial root of mandibular first molars had two canals in 96.3% of the teeth in both males and females and-type IV canal configuration was most prevalent in the mesial root. The distal root of the mandibular first molar had one canal in 57.7% of the teeth in males and females. There were significant gender variations in the number of canals and canal configurations in the distal root. Two canals were more prevalent in females (53.6%) compared to males (30.4%) and a single canal was more frequent in males (69.6%) compared to females (46.4%) (P=0.001). Canal types 1, 11 and IV were the most frequent in the mandibular distal root. The gender variation in the frequency of canal types I, II and IV in the distal root was statistically significant (P=0.001). Most of the mandibular first molars have three canals (56%). Two canals in the distal root are more frequent among females (53.6%) compared to males (30.4%).

Statistical Aspects of the North Atlantic Basin Tropical Cyclones: Trends, Natural Variability, and Global Warming

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2007-01-01

Statistical aspects of the North Atlantic basin tropical cyclones for the interval 1945- 2005 are examined, including the variation of the yearly frequency of occurrence for various subgroups of storms (all tropical cyclones, hurricanes, major hurricanes, U.S. landfalling hurricanes, and category 4/5 hurricanes); the yearly variation of the mean latitude and longitude (genesis location) of all tropical cyclones and hurricanes; and the yearly variation of the mean peak wind speeds, lowest pressures, and durations for all tropical cyclones, hurricanes, and major hurricanes. Also examined is the relationship between inferred trends found in the North Atlantic basin tropical cyclonic activity and natural variability and global warming, the latter described using surface air temperatures from the Armagh Observatory Armagh, Northern Ireland. Lastly, a simple statistical technique is employed to ascertain the expected level of North Atlantic basin tropical cyclonic activity for the upcoming 2007 season.

Toward Failure Modeling In Complex Dynamic Systems: Impact of Design and Manufacturing Variations

NASA Technical Reports Server (NTRS)

Tumer, Irem Y.; McAdams, Daniel A.; Clancy, Daniel (Technical Monitor)

2001-01-01

When designing vehicle vibration monitoring systems for aerospace devices, it is common to use well-established models of vibration features to determine whether failures or defects exist. Most of the algorithms used for failure detection rely on these models to detect significant changes during a flight environment. In actual practice, however, most vehicle vibration monitoring systems are corrupted by high rates of false alarms and missed detections. Research conducted at the NASA Ames Research Center has determined that a major reason for the high rates of false alarms and missed detections is the numerous sources of statistical variations that are not taken into account in the. modeling assumptions. In this paper, we address one such source of variations, namely, those caused during the design and manufacturing of rotating machinery components that make up aerospace systems. We present a novel way of modeling the vibration response by including design variations via probabilistic methods. The results demonstrate initial feasibility of the method, showing great promise in developing a general methodology for designing more accurate aerospace vehicle vibration monitoring systems.

The Influence of Host Galaxies in Type Ia Supernova Cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uddin, Syed A.; Mould, Jeremy; Lidman, Chris

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5 σ ), and decline more rapidly in massive hosts (significance >9 σ ) and in hosts with low specific star formation rates (significance >8 σ ). We studymore » the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter ( σ {sub int} = 0.08 ± 0.01) in luminosity after standardization.« less

The Influence of Host Galaxies in Type Ia Supernova Cosmology

NASA Astrophysics Data System (ADS)

Uddin, Syed A.; Mould, Jeremy; Lidman, Chris; Ruhlmann-Kleider, Vanina; Zhang, Bonnie R.

2017-10-01

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5σ), and decline more rapidly in massive hosts (significance >9σ) and in hosts with low specific star formation rates (significance >8σ). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter (σ int = 0.08 ± 0.01) in luminosity after standardization.

Differential diagnosis of cardiovascular diseases and T-wave alternans

NASA Astrophysics Data System (ADS)

Ramasamy, Mouli; Varadan, Vijay K.

2016-04-01

T wave alternans (TWA) is the variation of the T-wave in electrocardiogram that is observed between periodic beats. TWA is one of the important precursors used to diagnose sudden cardiac death (SCD). Several clinical studies have tried to determine the significance of using TWA analysis to detect abnormalities that may lead to Ventricular Arrhythmias, as well as establish metrics to perform risk stratification for cardiovascular patients with prior cardiac episodes. The statistical significance of TWA in predicting ventricular arrhythmias has been established in patients across several diagnoses. Studies have also shown the significance of the predictive value of TWA analysis in post myocardial infarction patients, risk of SCD, congestive heart failure, ischemic cardiomyopathy, and Chagas disease.

In vitro cavity and crown preparations and direct restorations: A comparison of performance at the start and end of the FD programme.

PubMed

Burke, F J T; Ravaghi, V; Mackenzie, L; Priest, N; Falcon, H C

2017-04-21

Aim To assess the performance and thereby the progress of the FDs when they carried out a number of simulated clinical exercises at the start and at the end of their FD year.Methods A standardised simulated clinical restorative dentistry training exercise was carried out by a group of 61 recently qualified dental graduates undertaking a 12 months' duration foundation training programme in England, at both the start and end of the programme. Participants completed a Class II cavity preparation and amalgam restoration, a Class IV composite resin restoration and two preparations for a porcelain-metal full crown. The completed preparations and restorations were independently assessed by an experienced consultant in restorative dentistry, using a scoring system based on previously validated criteria. The data were subjected to statistical analysis.Results There was wide variation in individual performance. Overall, there was a small but not statistically significant improvement in performance by the end of the programme. A statistically significant improvement was observed for the amalgam preparation and restoration, and, overall, for one of the five geographical sub-groups in the study. Possible reasons for the variable performance and improvement are discussed.Conclusions There was variability in the performance of the FDs. The operative performance of FDs at the commencement and end of their FD year indicated an overall moderately improved performance over the year and a statistically significant improvement in their performance with regard to amalgam restoration.

Temperature variation during apicectomy with Er:YAG laser.

PubMed

Bodrumlu, Emre; Keskiner, Ilker; Sumer, Mahmut; Sumer, A Pinar; Telcıoglu, N Tuba

2012-08-01

The purpose of this in vitro study was to evaluate the generated temperature of the Er:YAG laser, with three different pulse durations for apicectomy, compared with tungsten bur and surgical saw. Apicectomy is an endodontic surgery performed to remove the root apex and curette adjacent periapical tissue because of lesions of the apical area that are not healing properly. Sixty single-rooted extracted human teeth were resected by three cutting methods: tungsten bur, surgical saw, and Er:YAG laser irradiation with three different pulse durations; pulse duration 50 μs, pulse duration 100 μs, and pulse duration 300 μs. Teflon-insulated, type K thermocouples were used to measure temperature changes during the apicectomy process. Data were analyzed using the general linear models procedure of the SPSS statistical software program. Although there was no statistically significant difference for the mean values of temperature changes at 1 mm away to the cutting site of teeth, there was statistically significant difference among groups for the mean values of temperature changes at 3 mm away to the cutting site of teeth. Additionally, there was statistically significant difference among groups for the total time required for apicectomy. The laser irradiation with pulse duration 50 μs appears to have the lowest temperature rise and the shortest time required for apicectomy of the three pulse durations. However, Er:YAG laser for apicectomy in all pulse durations could be used safely for resection in endodontics in the presence of sufficient water.

Trends in thermal discomfort indices over western coastal cities of India

NASA Astrophysics Data System (ADS)

Desai, Manasi S.; Dhorde, Amit G.

2018-02-01

The present research aimed at analyzing temporal trends in thermal discomfort indices for a period of 46 years from 1969 to 2014 over western coastal region of India for seven urban centers during the months of pre-monsoon and monsoon seasons. Direct thermal discomfort indices employed for this purpose were thermo-hygrometric index (THI) and heat index (HI). Statistical techniques applied for obtaining temporal trends were linear regression model and Mann-Kendall (MK) rank test. Statistical significance of the obtained trends was evaluated at 95% confidence level. Sequential MK (SQ-MK) test was used for change point detection. To investigate actual incidences of thermal discomfort, daily index values were averaged for standard meteorological weeks (SMWs) over the study period and decadal percentage of thermal discomfort during SMWs was estimated. Trend analysis of selected meteorological parameters such as dry bulb temperature (DBT), wet bulb temperature (WBT), relative humidity (RH), and wind speed (WS) were investigated, which might be responsible for variation in thermal discomfort over the period. The results obtained depicted significant increase in thermal discomfort over the cities located on the southern part of west coast, while significant increase was observed during monsoon season months compared to pre-monsoon season. Decadal variation in percentage of SMWs falling in various discomfort categories was studied. At majority of the stations, moderate and high-risk SMWs have increased over the last two decades. The results of change point detection for THI and HI denoted significant increase at most of the stations after 1990s. The study validates increase in thermal discomfort vulnerability, particularly at thriving urban centers of western coastal region of India.

Spatio-temporal variability of non-regulated disinfection by-products within a drinking water distribution network.

PubMed

Mercier Shanks, Catherine; Sérodes, Jean-Baptiste; Rodriguez, Manuel J

2013-06-01

The non-regulated disinfection by-products (NrDBP) targeted in this study include four haloacetonitriles (trichloroacetonitrile (TCAN); dichloroacetonitrile (DCAN); bromochloroacetonitrile (BCAN) and dibromoacetonitrile (DBAN)); one halonitromethane (trichloronitromethane, better known under the name chloropicrin (CPK)); and two haloketones (1,1-dichloro-2-propanone (11DCPone) and 1,1,1-trichloro-2-propanone (111TCPone)). This study provides a detailed picture of the spatial and temporal variability of these NrDBP concentrations throughout a drinking water distribution system located in a region with major seasonal climate variations. The results obtained show that the concentrations of the investigated NrDBPs varied significantly according to time and location. The average concentrations of TCAN, DCAN, CKP and 111TCPone were significantly higher in summer. Surprisingly, the average concentrations of 11DCPone were significantly higher in winter. For BCAN and DBAN, the average concentrations observed in winter were higher, but not in a statistically significant way. On the other hand, the four HANs, CPK and 111TCPone generally had spatial profiles involving an increase of the concentrations along the network according to increasing water residence times, whereas 11DCPone overall had a profile where concentrations increased at the beginning of the network, followed by a drop in the concentrations towards the ends of the network. In spite of certain disparities in the individual spatio-temporal variation profiles, strong correlations were generally observed between NrDBPs, and trihalomethanes (THMs) and haloacetic acids (HAAs). Therefore, THMs and HAAs could be good statistical indicators of the presence of NrDBPs in the drinking water of the system under study. Copyright © 2013 Elsevier Ltd. All rights reserved.

Liver stiffness and portal blood flow modifications induced by a liquid meal consumption: pathogenetic mechanisms and clinical relevance.

PubMed

Barone, Michele; Iannone, Andrea; Brunetti, Natale Daniele; Sebastiani, Francesco; Cecere, Onofrio; Berardi, Elsa; Antonica, Gianfranco; Di Leo, Alfredo

2015-05-01

The correlation between liver stiffness (LS) variations and portal blood flow (PBF) modifications induced by a standardized liquid meal consumption and the clinical relevance of this matter are two aspects not yet fully elucidated. Herein, we evaluated the variations of LS and PBF after a standardized liquid meal intake in patients with chronic liver disease. PBF and LS were determined after an overnight fasting period in 54 patients. They were divided in three groups according to baseline LS (absent, moderate, and severe). They consumed 200 ml of water and a standardized liquid meal (300 Kcal/200 ml) after 60 min. PBF and LS were measured at 30 min after water and liquid meal consumption. In all groups, LS and PBF values significantly increased only after meal consumption. A significant correlation between baseline LS values and post-meal increase of LS was observed. Moreover, higher basal stiffness values were associated to a larger increase of LS variation after meal consumption. The effect of the meal on LS remained statistically significant after multiple regression analysis. A significant correlation between increase of LS and PBF was found in patients with absent and moderate baseline LS. Nine patients (17%) switched from a lower to a higher level of LS after meal consumption. A low calories/low-volume meal is capable of significantly increasing LS regardless of the grade of stiffness, determining a reclassification rate of 17%. In presence of minimal or moderate stiffness, the increase of LS is significantly correlated with the augment of PBF.

Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data

PubMed Central

Kim, Sung-Min; Choi, Yosoon

2017-01-01

To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z-score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z-scores: high content with a high z-score (HH), high content with a low z-score (HL), low content with a high z-score (LH), and low content with a low z-score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1–4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required. PMID:28629168

Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data.

PubMed

Kim, Sung-Min; Choi, Yosoon

2017-06-18

To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z -score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z -scores: high content with a high z -score (HH), high content with a low z -score (HL), low content with a high z -score (LH), and low content with a low z -score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1-4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required.

SEGMENTING CT PROSTATE IMAGES USING POPULATION AND PATIENT-SPECIFIC STATISTICS FOR RADIOTHERAPY.

PubMed

Feng, Qianjin; Foskey, Mark; Tang, Songyuan; Chen, Wufan; Shen, Dinggang

2009-08-07

This paper presents a new deformable model using both population and patient-specific statistics to segment the prostate from CT images. There are two novelties in the proposed method. First, a modified scale invariant feature transform (SIFT) local descriptor, which is more distinctive than general intensity and gradient features, is used to characterize the image features. Second, an online training approach is used to build the shape statistics for accurately capturing intra-patient variation, which is more important than inter-patient variation for prostate segmentation in clinical radiotherapy. Experimental results show that the proposed method is robust and accurate, suitable for clinical application.

SEGMENTING CT PROSTATE IMAGES USING POPULATION AND PATIENT-SPECIFIC STATISTICS FOR RADIOTHERAPY

PubMed Central

Feng, Qianjin; Foskey, Mark; Tang, Songyuan; Chen, Wufan; Shen, Dinggang

2010-01-01

This paper presents a new deformable model using both population and patient-specific statistics to segment the prostate from CT images. There are two novelties in the proposed method. First, a modified scale invariant feature transform (SIFT) local descriptor, which is more distinctive than general intensity and gradient features, is used to characterize the image features. Second, an online training approach is used to build the shape statistics for accurately capturing intra-patient variation, which is more important than inter-patient variation for prostate segmentation in clinical radiotherapy. Experimental results show that the proposed method is robust and accurate, suitable for clinical application. PMID:21197416

Finding a Needle in a Climate Haystack

NASA Astrophysics Data System (ADS)

Verosub, K. L.; Medrano, R.; Valentine, M.

2014-12-01

We are studying the regional impact of volcanic eruptions that might have caused global cooling using high-quality annual-resolution proxy records of natural phenomena, such as tree-ring widths, and cultural events, such as the dates of the beginning of grape and rye harvests. To do this we need to determine if the year following an eruption was significantly colder and wetter than preceding or subsequent years as measured by any given proxy and if that year is consistently cold and wet across different proxies. The problem is complicated by the fact that normal inter-annual variations in any given proxy can be quite large and can obscure any volcanological impact and by the fact that inter-annual variations for different proxies will have different means and standard deviations. We address the first problem by assuming that on a regional scale, the inter-annual variations of different proxies are at best only weakly correlated and that, in the absence of a volcanological signal, these variations will average out on a regional scale. We address the second problem by renormalizing each record so that it has the same mean and standard deviation over a given time interval. We then sum the re-normalized records on a year-by-year basis and look for years with significantly higher total scores. The method can also be used to assess the statistical significance of an anomalous value. Our initial analysis of records primarily from the Northern Hemisphere shows that the years 1601 and 1816 were significantly colder and wetter than any others in the past 500 years. These years followed the eruptions of Huayanaputina in Chile and Tambora in Indonesia, respectively, by one year. The years 1698 and 1837 also show up as being climatologically severe although they have not (yet) been associated with specific volcanic eruptions.

Vocal mechanics in Darwin's finches: correlation of beak gape and song frequency.

PubMed

Podos, Jeffrey; Southall, Joel A; Rossi-Santos, Marcos R

2004-02-01

Recent studies of vocal mechanics in songbirds have identified a functional role for the beak in sound production. The vocal tract (trachea and beak) filters harmonic overtones from sounds produced by the syrinx, and birds can fine-tune vocal tract resonance properties through changes in beak gape. In this study, we examine patterns of beak gape during song production in seven species of Darwin's finches of the Galápagos Islands. Our principal goals were to characterize the relationship between beak gape and vocal frequency during song production and to explore the possible influence therein of diversity in beak morphology and body size. Birds were audio and video recorded (at 30 frames s(-1)) as they sang in the field, and 164 song sequences were analyzed. We found that song frequency regressed significantly and positively on beak gape for 38 of 56 individuals and for all seven species examined. This finding provides broad support for a resonance model of vocal tract function in Darwin's finches. Comparison among species revealed significant variation in regression y-intercept values. Body size correlated negatively with y-intercept values, although not at a statistically significant level. We failed to detect variation in regression slopes among finch species, although the regression slopes of Darwin's finch and two North American sparrow species were found to differ. Analysis within one species (Geospiza fortis) revealed significant inter-individual variation in regression parameters; these parameters did not correlate with song frequency features or plumage scores. Our results suggest that patterns of beak use during song production were conserved during the Darwin's finch adaptive radiation, despite the evolution of substantial variation in beak morphology and body size.

Estimating the Medical Care Costs of Obesity in the United States: Systematic Review, Meta-Analysis, and Empirical Analysis.

PubMed

Kim, David D; Basu, Anirban

2016-01-01

The prevalence of adult obesity exceeds 30% in the United States, posing a significant public health concern as well as a substantial financial burden. Although the impact of obesity on medical spending is undeniably significant, the estimated magnitude of the cost of obesity has varied considerably, perhaps driven by different study methodologies. To document variations in study design and methodology in existing literature and to understand the impact of those variations on the estimated costs of obesity. We conducted a systematic review of the twelve recently published articles that reported costs of obesity and performed a meta-analysis to generate a pooled estimate across those studies. Also, we performed an original analysis to understand the impact of different age groups, statistical models, and confounder adjustment on the magnitude of estimated costs using the nationally representative Medical Expenditure Panel Surveys from 2008-2010. We found significant variations among cost estimates in the existing literature. The meta-analysis found that the annual medical spending attributable to an obese individual was $1901 ($1239-$2582) in 2014 USD, accounting for $149.4 billion at the national level. The two most significant drivers of variability in the cost estimates were age groups and adjustment for obesity-related comorbid conditions. It would be important to acknowledge variations in the magnitude of the medical cost of obesity driven by different study design and methodology. Researchers and policy-makers need to be cautious on determining appropriate cost estimates according to their scientific and political questions. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Modelling multiple hospital outcomes: the impact of small area and primary care practice variation.

PubMed

Congdon, Peter

2006-11-16

Appropriate management of care--for example, avoiding unnecessary attendances at, or admissions to, hospital emergency units when they could be handled in primary care--is an important part of health strategy. However, some variations in these outcomes could be due to genuine variations in health need. This paper proposes a new method of explaining variations in hospital utilisation across small areas and the general practices (GPs) responsible for patient primary care. By controlling for the influence of true need on such variations, one may identify remaining sources of excess emergency attendances and admissions, both at area and practice level, that may be related to the quality, resourcing or organisation of care. The present paper accordingly develops a methodology that recognises the interplay between population mix factors (health need) and primary care factors (e.g. referral thresholds), that allows for unobserved influences on hospitalisation usage, and that also reflects interdependence between hospital outcomes. A case study considers relativities in attendance and admission rates at a North London hospital involving 149 small areas and 53 GP practices. A fixed effects model shows variations in attendances and admissions are significantly related (positively) to area and practice need, and nursing home patients, and related (negatively) to primary care access and distance of patient homes from the hospital. Modelling the impact of known factors alone is not sufficient to produce a satisfactory fit to the observations, and random effects at area and practice level are needed to improve fit and account for overdispersion. The case study finds variation in attendance and admission rates across areas and practices after controlling for need, and remaining differences between practices may be attributable to referral behaviour unrelated to need, or to staffing, resourcing, and access issues. In managerial terms, the analysis points to the utility of formal statistical analysis of hospitalisation rates as a prelude to non-statistical investigation of primary care resourcing and organisation. For example, there may be implications for the location of staff involved in community management of chronic conditions; health managers may also investigate whether some practices have unusual populations (homeless, asylum seekers, students) that explain different hospital use patterns.

Spatial pattern of spring phytoplankton community in the coastal waters of northern Zhejiang, East China Sea

NASA Astrophysics Data System (ADS)

Ye, Ran; Cai, Yanhong; Wei, Yongjie; Li, Xiaoming

2017-04-01

The spatial pattern of phytoplankton community can indicate potential environmental variation in different water bodies. In this context, spatial pattern of phytoplankton community and its response to environmental and spatial factors were studied in the coastal waters of northern Zhejiang, East China Sea using multivariate statistical techniques. Results showed that 94 species belonging to 40 genera, 5 phyla were recorded (the remaining 9 were identified to genus level) with diatoms being the most dominant followed by dinoflagellates. Hierarchical clustering analysis (HCA), nonmetric multidimentional scaling (NMDS), and analysis of similarity (ANOSIM) all demomstrated that the whole study area could be divided into 3 subareas with significant differences. Indicator species analysis (ISA) further confirmed that the indicator species of each subarea correlated significantly with specific environmental factors. Distance-based linear model (Distlm) and Mantel test revealed that silicate (SiO32-), phosphate (PO43-), pH, and dissolved oxygen (DO) were the most important environmental factors influencing phytoplankton community. Variation portioning (VP) finally concluded that the shared fractions of environmental and spatial factors were higher than either the pure environmental effects or the pure spatial effects, suggesting phytoplankton biogeography were mainly affected by both the environmental variability and dispersal limitation. Additionally, other factors (eg., trace metals, biological grazing, climate change, and time-scale variation) may also be the sources of the unexplained variation which need further study.

Natural Genetic Variation Influences Protein Abundances in C. elegans Developmental Signalling Pathways

PubMed Central

Singh, Kapil Dev; Roschitzki, Bernd; Snoek, L. Basten; Grossmann, Jonas; Zheng, Xue; Elvin, Mark; Kamkina, Polina; Schrimpf, Sabine P.; Poulin, Gino B.; Kammenga, Jan E.; Hengartner, Michael O.

2016-01-01

Complex traits, including common disease-related traits, are affected by many different genes that function in multiple pathways and networks. The apoptosis, MAPK, Notch, and Wnt signalling pathways play important roles in development and disease progression. At the moment we have a poor understanding of how allelic variation affects gene expression in these pathways at the level of translation. Here we report the effect of natural genetic variation on transcript and protein abundance involved in developmental signalling pathways in Caenorhabditis elegans. We used selected reaction monitoring to analyse proteins from the abovementioned four pathways in a set of recombinant inbred lines (RILs) generated from the wild-type strains N2 (Bristol) and CB4856 (Hawaii) to enable quantitative trait locus (QTL) mapping. About half of the cases from the 44 genes tested showed a statistically significant change in protein abundance between various strains, most of these were however very weak (below 1.3-fold change). We detected a distant QTL on the left arm of chromosome II that affected protein abundance of the phosphatidylserine receptor protein PSR-1, and two separate QTLs that influenced embryonic and ionizing radiation-induced apoptosis on chromosome IV. Our results demonstrate that natural variation in C. elegans is sufficient to cause significant changes in signalling pathways both at the gene expression (transcript and protein abundance) and phenotypic levels. PMID:26985669

Evaluation of Blue Crab, Callinectes sapidus, Megalopal Settlement and Condition during the Deepwater Horizon Oil Spill

PubMed Central

Grey, Erin K.; Chiasson, Susan C.; Williams, Hannah G.; Troeger, Victoria J.; Taylor, Caz M.

2015-01-01

The Blue Crab, Callinectes sapidus, is a commercially, culturally, and ecologically significant species in the Gulf of Mexico (GOM), whose offshore stages were likely impacted by the Deepwater Horizon oil spill (DWH). To test for DWH effects and to better understand the planktonic ecology of this species, we monitored Callinectes spp. megalopal settlement and condition at sites within and outside of the spill extent during and one year after the DWH. We tested for DWH effects by comparing 2010 settlement against baseline data available for two sites, and by testing for differences in settlement and condition inside and outside of the spill extent. We also developed time series models to better understand natural drivers of daily settlement variation (seasonal and lunar trends, hydrodynamics, wind) during 2010 and 2011. Overall, we found that neither megalopal settlement nor body weight were significantly reduced at oiled sites, but that high unexplained variation and low statistical power made detection of even large effects unlikely. Time series models revealed remarkably consistent and relatively strong seasonal and lunar trends within sites (explaining on average 28% and 9% of variation, respectively), while wind and hydrodynamic effects were weak (1–5% variation explained) and variable among sites. This study provides insights into DWH impacts as well as the natural drivers of Callinectes spp. megalopal settlement across the northern GOM. PMID:26270970

Variations in the abundance of iron on Mercury's surface from MESSENGER X-Ray Spectrometer observations

NASA Astrophysics Data System (ADS)

Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Solomon, Sean C.

2014-06-01

We present measurements of Mercury's surface composition from the analysis of MESSENGER X-Ray Spectrometer data acquired during 55 large solar flares, which each provide a statistically significant detection of Fe X-ray fluorescence. The Fe/Si data display a clear dependence on phase angle, for which the results are empirically corrected. Mercury's surface has a low total abundance of Fe, with a mean Fe/Si ratio of ˜0.06 (equivalent to ˜1.5 wt% Fe). The absolute Fe/Si values are subject to a number of systematic uncertainties, including the phase-angle correction and possible mineral mixing effects. Individual Fe/Si measurements have an intrinsic error of ˜10%. Observed Fe/Si values display small variations (significant at two standard deviations) from the planetary average value across large regions in Mercury's southern hemisphere. Larger differences are observed between measured Fe/Si values from more spatially resolved footprints on volcanic smooth plains deposits in the northern hemisphere and from those in surrounding terrains. Fe is most likely contained as a minor component in sulfide phases (e.g., troilite, niningerite, daubréelite) and as Fe metal, rather than within mafic silicates. Variations in surface reflectance (i.e., differences in overall reflectance and spectral slope) across Mercury are unlikely to be caused by variations in the abundance of Fe.

Effect of Ramadan intermittent fasting on selective fitness profile parameters in young untrained Muslim men.

PubMed

Roy, Anindita Singha; Bandyopadhyay, Amit

2015-01-01

The present study was aimed at investigating the effects of sleep deprivation and dietary irregularities during Ramadan intermittent fasting (RIF) on selective fitness profile parameters in young untrained male Muslim individuals. 77 untrained Muslim men were recruited in the study. They were divided into the experimental group (EG; n=37, age: 22.62±1.77 years) and the control group (CG; n=40, age: 23.00±1.48 years). EG was undergoing RIF while CG abstained. Aerobic fitness, anaerobic capacity or high-intensity efforts (HIEs), agility, flexibility, vertical jump height and handgrip strength were measured on 8 separate occasions-15 days before RIF, 7 days before RIF, 1st day of RIF, 7th day of RIF, 15th day of RIF, 21st day of RIF, last day of RIF and 15 days after RIF. Aerobic fitness and HIE showed a significant difference (p<0.05) during RIF in EG. Agility and flexibility score showed a significant decrease in EG during RIF, whereas changes in the vertical jump score (VJT) and handgrip strength were statistically insignificant. Studied parameters showed an insignificant variation in CG during RIF. Aerobic fitness, HIEs, agility and flexibility showed a significant intergroup variation during different experimental trials. The present investigation revealed that RIF had adverse effects on aerobic fitness, HIEs, agility and flexibility of young untrained Muslims of Kolkata, India. VJT, waist-hip ratio and handgrip strength were not affected by RIF in the studied population. Mild but statistically insignificant reduction in body mass was also reflected after the mid-Ramadan week.

Effects of Microstructural Parameters on Creep of Nickel-Base Superalloy Single Crystals

NASA Technical Reports Server (NTRS)

MacKay, Rebecca A.; Gabb, Timothy P.; Nathal, Michael V.

2013-01-01

Microstructure-sensitive creep models have been developed for Ni-base superalloy single crystals. Creep rupture testing was conducted on fourteen single crystal alloys at two applied stress levels at each of two temperatures, 982 and 1093 C. The variation in creep lives among the different alloys could be explained with regression models containing relatively few microstructural parameters. At 982 C, gamma-gamma prime lattice mismatch, gamma prime volume fraction, and initial gamma prime size were statistically significant in explaining the creep rupture lives. At 1093 C, only lattice mismatch and gamma prime volume fraction were significant. These models could explain from 84 to 94 percent of the variation in creep lives, depending on test condition. Longer creep lives were associated with alloys having more negative lattice mismatch, lower gamma prime volume fractions, and finer gamma prime sizes. The gamma-gamma prime lattice mismatch exhibited the strongest influence of all the microstructural parameters at both temperatures. Although a majority of the alloys in this study were stable with respect to topologically close packed (TCP) phases, it appeared that up to approximately 2 vol% TCP phase did not affect the 1093 C creep lives under applied stresses that produced lives of approximately 200 to 300 h. In contrast, TCP phase contents of approximately 2 vol% were detrimental at lower applied stresses where creep lives were longer. A regression model was also developed for the as-heat treated initial gamma prime size; this model showed that gamma prime solvus temperature, gamma-gamma prime lattice mismatch, and bulk Re content were all statistically significant.

Input respiratory impedance in mice: comparison between the flow-based and the wavetube method to perform the forced oscillation technique.

PubMed

Mori, V; Oliveira, M A; Vargas, M H M; da Cunha, A A; de Souza, R G; Pitrez, P M; Moriya, H T

2017-06-01

Objective and approach: In this study, we estimated the constant phase model (CPM) parameters from the respiratory impedance of male BALB/c mice by performing the forced oscillation technique (FOT) in a control group (n  =  8) and in a murine model of asthma (OVA) (n  =  10). Then, we compared the results obtained by two different methods, using a commercial equipment (flexiVent-flexiWare 7.X; SCIREQ, Montreal, Canada) (FXV) and a wavetube method equipment (Sly et al 2003 J. Appl. Physiol. 94 1460-6) (WVT). We believe that the results from different methods may not be comparable. First, we compared the results performing a two-way analysis of variance (ANOVA) for the resistance, elastance and tissue damping. We found statistically significant differences in all CPM parameters, except for resistance, when comparing Control and OVA groups. When comparing devices, we found statistically significant differences in resistance, while differences in elastance were not observed. For tissue damping, the results from WVT were observed to be higher than those from FXV. Finally, when comparing the relative variation between the CPM parameters of the Control and OVA groups in both devices, no significant differences were observed for all parameters. We then conclude that this assessment can compensate the effect of using different cannulas. Furthermore, tissue damping differences between groups can be compensated, since bronchoconstrictors were not used. Therefore, we believe that relative variations in the results between groups can be a comparing parameter when using different equipment without bronchoconstrictor administration.

Comparison of biometric measurements obtained by the Verion Image-Guided System versus the auto-refracto-keratometer.

PubMed

Velasco-Barona, Cecilio; Cervantes-Coste, Guadalupe; Mendoza-Schuster, Erick; Corredor-Ortega, Claudia; Casillas-Chavarín, Nadia L; Silva-Moreno, Alejandro; Garza-León, Manuel; Gonzalez-Salinas, Roberto

2018-06-01

To compare the biometric measurements obtained from the Verion Image-Guided System to those obtained by auto-refracto-keratometer in normal eyes. This is a prospective, observational, comparative study conducted at the Asociación para Evitar la Ceguera en México I.A.P., Mexico. Three sets of keratometry measurements were obtained using the image-guided system to assess the coefficient of variation, the within-subject standard deviation and intraclass correlation coefficient (ICC). A paired Student t test was used to assess statistical significance between the Verion and the auto-refracto-keratometer. A Pearson's correlation coefficient (r) was obtained for all measurements, and the level of agreement was verified using Bland-Altman plots. The right eyes of 73 patients were evaluated by each platform. The Verion coefficient of variation was 0.3% for the flat and steep keratometry, with the ICC being greater than 0.9 for all parameters measured. Paired t test showed statistically significant differences between groups (P = 0.0001). A good correlation was evidenced for keratometry values between platforms (r = 0.903, P = 0.0001 for K1, and r = 0.890, P = 0.0001). Bland-Altman plots showed a wide data spread for all variables. The image-guided system provided highly repeatable corneal power and keratometry measurements. However, significant differences were evidenced between the two platforms, and although values were highly correlated, they showed a wide data spread for all analysed variables; therefore, their interchangeable use for biometry assessment is not advisable.

Perianth organization and intra-specific floral variability.

PubMed

Herrera, J; Arista, M; Ortiz, P L

2008-11-01

Floral symmetry and fusion of perianth parts are factors that contribute to fine-tune the match between flowers and their animal pollination vectors. In the present study, we investigated whether the possession of a sympetalous (fused) corolla and bilateral symmetry of flowers translate into decreased intra-specific variability as a result of natural stabilizing selection exerted by pollinators. Average size of the corolla and intra-specific variability were determined in two sets of southern Spanish entomophilous plant species. In the first set, taxa were paired by family to control for the effect of phylogeny (phylogenetically independent contrasts), whereas in the second set species were selected at random. Flower size data from a previous study (with different species) were also used to test the hypothesis that petal fusion contributes to decrease intra-specific variability. In the phylogenetically independent contrasts, floral symmetry was a significant correlate of intra-specific variation, with bilaterally symmetrical flowers showing more constancy than radially symmetrical flowers (i.e. unsophisticated from a functional perspective). As regards petal fusion, species with fused petals were on average more constant than choripetalous species, but the difference was not statistically significant. The reanalysis of data from a previous study yielded largely similar results, with a distinct effect of symmetry on variability, but no effect of petal fusion. The randomly-chosen species sample, on the other hand, failed to reveal any significant effect of either symmetry or petal fusion on intra-specific variation. The problem of low-statistical power in this kind of analysis, and the difficulty of testing an evolutionary hypothesis that involves phenotypic traits with a high degree of morphological correlation is discussed.

Statistical model specification and power: recommendations on the use of test-qualified pooling in analysis of experimental data

PubMed Central

Colegrave, Nick

2017-01-01

A common approach to the analysis of experimental data across much of the biological sciences is test-qualified pooling. Here non-significant terms are dropped from a statistical model, effectively pooling the variation associated with each removed term with the error term used to test hypotheses (or estimate effect sizes). This pooling is only carried out if statistical testing on the basis of applying that data to a previous more complicated model provides motivation for this model simplification; hence the pooling is test-qualified. In pooling, the researcher increases the degrees of freedom of the error term with the aim of increasing statistical power to test their hypotheses of interest. Despite this approach being widely adopted and explicitly recommended by some of the most widely cited statistical textbooks aimed at biologists, here we argue that (except in highly specialized circumstances that we can identify) the hoped-for improvement in statistical power will be small or non-existent, and there is likely to be much reduced reliability of the statistical procedures through deviation of type I error rates from nominal levels. We thus call for greatly reduced use of test-qualified pooling across experimental biology, more careful justification of any use that continues, and a different philosophy for initial selection of statistical models in the light of this change in procedure. PMID:28330912

Comparable Wages, Inflation, and School Finance Equity

ERIC Educational Resources Information Center

Taylor, Lori L.

2006-01-01

A Comparable Wage Index (CWI) is an attractive mechanism for measuring geographic variations in the cost of education. A CWI measures uncontrollable variations in educator pay by observing systematic variations in the earnings of comparable workers who are not educators. Together, the 2000 census and the Occupational Employment Statistics survey…

WE-AB-209-12: Quasi Constrained Multi-Criteria Optimization for Automated Radiation Therapy Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, W.T.; Siebers, J.V.

Purpose: To introduce quasi-constrained Multi-Criteria Optimization (qcMCO) for unsupervised radiation therapy optimization which generates alternative patient-specific plans emphasizing dosimetric tradeoffs and conformance to clinical constraints for multiple delivery techniques. Methods: For N Organs At Risk (OARs) and M delivery techniques, qcMCO generates M(N+1) alternative treatment plans per patient. Objective weight variations for OARs and targets are used to generate alternative qcMCO plans. For 30 locally advanced lung cancer patients, qcMCO plans were generated for dosimetric tradeoffs to four OARs: each lung, heart, and esophagus (N=4) and 4 delivery techniques (simple 4-field arrangements, 9-field coplanar IMRT, 27-field non-coplanar IMRT, and non-coplanarmore » Arc IMRT). Quasi-constrained objectives included target prescription isodose to 95% (PTV-D95), maximum PTV dose (PTV-Dmax)< 110% of prescription, and spinal cord Dmax<45 Gy. The algorithm’s ability to meet these constraints while simultaneously revealing dosimetric tradeoffs was investigated. Statistically significant dosimetric tradeoffs were defined such that the coefficient of determination between dosimetric indices which varied by at least 5 Gy between different plans was >0.8. Results: The qcMCO plans varied mean dose by >5 Gy to ipsilateral lung for 24/30 patients, contralateral lung for 29/30 patients, esophagus for 29/30 patients, and heart for 19/30 patients. In the 600 plans computed without human interaction, average PTV-D95=67.4±3.3 Gy, PTV-Dmax=79.2±5.3 Gy, and spinal cord Dmax was >45 Gy in 93 plans (>50 Gy in 2/600 plans). Statistically significant dosimetric tradeoffs were evident in 19/30 plans, including multiple tradeoffs of at least 5 Gy between multiple OARs in 7/30 cases. The most common statistically significant tradeoff was increasing PTV-Dmax to reduce OAR dose (15/30 patients). Conclusion: The qcMCO method can conform to quasi-constrained objectives while revealing significant variations in OAR doses including mean dose reductions >5 Gy. Clinical implementation will facilitate patient-specific decision making based on achievable dosimetry as opposed to accept/reject models based on population derived objectives.« less

Statistical analysis of activation and reaction energies with quasi-variational coupled-cluster theory

NASA Astrophysics Data System (ADS)

Black, Joshua A.; Knowles, Peter J.

2018-06-01

The performance of quasi-variational coupled-cluster (QV) theory applied to the calculation of activation and reaction energies has been investigated. A statistical analysis of results obtained for six different sets of reactions has been carried out, and the results have been compared to those from standard single-reference methods. In general, the QV methods lead to increased activation energies and larger absolute reaction energies compared to those obtained with traditional coupled-cluster theory.

No association of SORL1 SNPs with Alzheimer's disease.

PubMed

Minster, Ryan L; DeKosky, Steven T; Kamboh, M Ilyas

2008-08-01

SORL1 is an element of the amyloid precursor protein processing pathway and is therefore a good candidate for affecting Alzheimer's disease (AD) risk. Indeed, there have been reports of associations between variation in SORL1 and AD risk. We examined six statistically significant single-nucleotide polymorphisms from the initial observation in a large Caucasian American case-controls cohort (1000 late-onset AD [LOAD] cases and 1000 older controls). Analysis of allele, genotype and haplotype frequencies revealed no association with LOAD risk in our cohort.

Leaf reflectance-nitrogen-chlorophyll relations among three south Texas woody rangeland plant species

NASA Technical Reports Server (NTRS)

Gausman, H. W.; Everitt, J. H.; Escobar, D. E. (Principal Investigator)

1982-01-01

Annual variations in the nitrogen-chlorophyll leaf reflectance of hackberry, honey mesquite and live oak in south Texas, were compared. In spring, leaf reflectance at the 0.55 m wavelength and nitrogen (N) concentration was high but leaf chlorophyll (chl) concentrations were low. In summer, leaf reflectance and N-concentration were low but lead chl concentrations were high. Linear correlations for both spring and summer of leaf reflectance with N and chl concentration or deviations from linear regression were not statistically significant.

A search for solar wind velocity changes between 0.7 and 1 AU

NASA Technical Reports Server (NTRS)

Intriligator, D. S.; Neugebauer, M.

1975-01-01

Observations are presented concerning the radial variations of the solar wind velocity between 0.7 and 1 AU in late 1968 and early 1969. The observations were made with instruments carried by Pioneer 9 and the earth-orbiting satellite OGO 5. The Pioneer and OGO velocity measurements are compared. It is found that the same basic solar wind velocity structure was seen at both spacecraft. No statistically significant dependence of average velocity on the radial distance from the sun could be observed.

Do slow orbital periodicities appear in the record of earth's magnetic reversals?

NASA Technical Reports Server (NTRS)

Stothers, Richard B.

1987-01-01

Time-series spectral analysis has been performed on the dates of geomagnetic reversals of the last 20 Myr BP and earlier. Possible evidence is found from the presence of high spectral peaks for two very long periodicities, 0.4 Myr and 1.3 Myr, that may be associated with slow variations of the earth's orbital eccentricity as predicted by Berger. However, statistical significance tests and a number of other arguments do not confirm the two detections.

Effectiveness of propolis on oral health: a meta-analysis.

PubMed

Hwu, Yueh-Juen; Lin, Feng-Yu

2014-12-01

The use of propolis mouth rinse or gel as a supplementary intervention has increased during the last decade in Taiwan. However, the effect of propolis on oral health is not well understood. The purpose of this meta-analysis was to present the best available evidence regarding the effects of propolis use on oral health, including oral infection, dental plaque, and stomatitis. Researchers searched seven electronic databases for relevant articles published between 1969 and 2012. Data were collected using inclusion and exclusion criteria. The Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument was used to evaluate the quality of the identified articles. Eight trials published from 1997 to 2011 with 194 participants had extractable data. The result of the meta-analysis indicated that, although propolis had an effect on reducing dental plaque, this effect was not statistically significant. The results were not statistically significant for oral infection or stomatitis. Although there are a number of promising indications, in view of the limited number and quality of studies and the variation in results among studies, this review highlights the need for additional well-designed trials to draw conclusions that are more robust.

Changing pattern of fascioliasis prevalence early in the 3rd millennium in Dakahlia Governorate, Egypt: an update.

PubMed

Adarosy, H A; Gad, Y Z; El-Baz, S A; El-Shazly, A M

2013-04-01

Fascioliasis is an important food- and water-borne parasitic zoonosis caused by liver flukes of genus Fasciola (Digenea: Fasciolidae) of worldwide distribution. In Egypt, fascioliasis was encountered in nearly all Egyptian Governorates, particularly in the Nile Delta and specifically in Dakahlia. All enrolled cases were subjected to complete history taking, clinical examination, routine investigations and abdominal ultrasonography. Stool analysis, IHA and ELISA were used for fascioliasis diagnosis. Rural areas showed highest prevalence of fascioliasis than urban areas, however, but.without significance (x2= 0.042 & P= 0.837). Regarding human fascioliasis in examined the centers, no statistically significant difference (x2 =2.824 & P=0.243) was detected. Regarding gender variation, the difference was statistically insignificant (x2= 0.166 & P= 0.683). The difference between the age groups was statistically insignificant (x2= 3.882 & P=0.274). Clinically, 7 cases (35%) were asymptomatic and another 13 cases (65%) had different clinical pictures. Abdominal pain, anemia, eosinophilia, and tender hepatomegaly were seen in 70%, 80%, 70%, and 10%; respectively. Of them, 1 1cases showed positive abdominal ultrasonographic findings suggestive of fascioliasis.

A genetic variant in SLC28A3, rs56350726, is associated with progression to castration-resistant prostate cancer in a Korean population with metastatic prostate cancer.

PubMed

Jo, Jung Ku; Oh, Jong Jin; Kim, Yong Tae; Moon, Hong Sang; Choi, Hong Yong; Park, Seunghyun; Ho, Jin-Nyoung; Yoon, Sungroh; Park, Hae Young; Byun, Seok-Soo

2017-11-14

Genetic variation which related with progression to castration-resistant prostate cancer (CRPC) during androgen-deprivation therapy (ADT) has not been elucidated in patients with metastatic prostate cancer (mPCa). Therefore, we assessed the association between genetic variats in mPCa and progession to CRPC. Analysis of exome genotypes revealed that 42 SNPs were significantly associated with mPCa. The top five polymorphisms were statistically significantly associated with metastatic disease. In addition, one of these SNPs, rs56350726, was significantly associated with time to CRPC in Kaplan-Meier analysis (Log-rank test, p = 0.011). In multivariable Cox regression, rs56350726 was strongly associated with progression to CRPC (HR = 4.172 95% CI = 1.223-14.239, p = 0.023). We assessed genetic variation among 1000 patients with PCa with or without metastasis, using 242,221 single nucleotide polymorphisms (SNPs) on the custom HumanExome BeadChip v1.0 (Illuminam Inc.). We analyzed the time to CRPC in 110 of the 1000 patients who were treated with ADT. Genetic data were analyzed using unconditional logistic regression and odds ratios calculated as estimates of relative risk of metastasis. We identified SNPs associated with metastasis and analyzed the relationship between these SNPs and time to CRPC in mPCa. Based on a genetic variation, the five top SNPs were observed to associate with mPCa. And one (SLC28A3, rs56350726) of five SNP was found the association with the progression to CRPC in patients with mPCa.

Codiversification of gastrointestinal microbiota and phylogeny in passerines is not explained by ecological divergence.

PubMed

Kropáčková, Lucie; Těšický, Martin; Albrecht, Tomáš; Kubovčiak, Jan; Čížková, Dagmar; Tomášek, Oldřich; Martin, Jean-François; Bobek, Lukáš; Králová, Tereza; Procházka, Petr; Kreisinger, Jakub

2017-10-01

Vertebrate gut microbiota (GM) is comprised of a taxonomically diverse consortium of symbiotic and commensal microorganisms that have a pronounced effect on host physiology, immune system function and health status. Despite much research on interactions between hosts and their GM, the factors affecting inter- and intraspecific GM variation in wild populations are still poorly known. We analysed data on faecal microbiota composition in 51 passerine species (319 individuals) using Illumina MiSeq sequencing of bacterial 16S rRNA (V3-V4 variable region). Despite pronounced interindividual variation, GM composition exhibited significant differences at the interspecific level, accounting for approximately 20%-30% of total GM variation. We also observed a significant correlation between GM composition divergence and host's phylogenetic divergence, with strength of correlation higher than that of GM vs. ecological or life history traits and geographic variation. The effect of host's phylogeny on GM composition was significant, even after statistical control for these confounding factors. Hence, our data do not support codiversification of GM and passerine phylogeny solely as a by-product of their ecological divergence. Furthermore, our findings do not support that GM vs. host's phylogeny codiversification is driven primarily through trans-generational GM transfer as the GM vs. phylogeny correlation does not increase with higher sequence similarity used when delimiting operational taxonomic units. Instead, we hypothesize that the GM vs. phylogeny correlation may arise as a consequence of interspecific divergence of genes that directly or indirectly modulate composition of GM. © 2017 John Wiley & Sons Ltd.

Recovering incomplete data using Statistical Multiple Imputations (SMI): a case study in environmental chemistry.

PubMed

Mercer, Theresa G; Frostick, Lynne E; Walmsley, Anthony D

2011-10-15

This paper presents a statistical technique that can be applied to environmental chemistry data where missing values and limit of detection levels prevent the application of statistics. A working example is taken from an environmental leaching study that was set up to determine if there were significant differences in levels of leached arsenic (As), chromium (Cr) and copper (Cu) between lysimeters containing preservative treated wood waste and those containing untreated wood. Fourteen lysimeters were setup and left in natural conditions for 21 weeks. The resultant leachate was analysed by ICP-OES to determine the As, Cr and Cu concentrations. However, due to the variation inherent in each lysimeter combined with the limits of detection offered by ICP-OES, the collected quantitative data was somewhat incomplete. Initial data analysis was hampered by the number of 'missing values' in the data. To recover the dataset, the statistical tool of Statistical Multiple Imputation (SMI) was applied, and the data was re-analysed successfully. It was demonstrated that using SMI did not affect the variance in the data, but facilitated analysis of the complete dataset. Copyright © 2011 Elsevier B.V. All rights reserved.

Ultraviolet continuum variability and visual flickering in the peculiar object MWC 560

NASA Technical Reports Server (NTRS)

Michalitsianos, A. G.; Perez, M.; Shore, S. N.; Maran, S. P.; Karovska, M.; Sonneborn, G.; Webb, J. R.; Barnes, Thomas G., III; Frueh, Marian L.; Oliversen, R. J.

1993-01-01

High-speed U-band photometry of the peculiar emission object MWC 560 obtained with the ground-based instrumentation, and V-band photometry obtained with the International Ultraviolet Explorer-Fine Error Sensor indicates irregular brightness variations are quasi-periodic. Multiple peaks of relative brightness power indicate statistically significant quasi periods existing in a range of 3-35 minutes, that are superposed on slower hourly varying components. We present a preliminary model that explains the minute and hourly time-scale variations in MWC 560 in terms of a velocity-shear instability that arises because a white dwarf magnetosphere impinges on an accretion disk. We also find evidence for Fe II multiplet pseudocontinuum absorption opacity in far-UV spectra of CH Cygni which is also present in MWC 560. Both CH Cyg and MWC 560 may be in an evolutionary stage that is characterized by strong UV continuum opacity which changes significantly during outburst, occurring before they permanently enter the symbiotic nebular emission phase.

Transit Timing Observations from Kepler. IX. Catalog of the Full Long-cadence Data Set

NASA Astrophysics Data System (ADS)

Holczer, Tomer; Mazeh, Tsevi; Nachmani, Gil; Jontof-Hutter, Daniel; Ford, Eric B.; Fabrycky, Daniel; Ragozzine, Darin; Kane, Mackenzie; Steffen, Jason H.

2016-07-01

We present a new transit timing catalog of 2599 Kepler Objects of Interest (KOIs), using the PDC-MAP long-cadence light curves that include the full 17 quarters of the mission (ftp://wise-ftp.tau.ac.il/pub/tauttv/TTV/ver_112). The goal is to produce an easy-to-use catalog that can stimulate further analyses of interesting systems. For 779 KOIs with high enough S/N, we derived the timing, duration, and depth of 69,914 transits. For 1820 KOIs with lower SNR, we derived only the timing of 225,273 transits. After removal of outlier timings, we derived various statistics for each KOI that were used to indicate significant variations. Including systems found by previous works, we have detected 260 KOIs that showed significant TTVs with long-term variations (>100 days), and another 14 KOIs with periodic modulations shorter than 100 days and small amplitudes. For five of those, the periodicity is probably due to the crossing of rotating stellar spots by the transiting planets.

NMR analysis of seven selections of vermentino grape berry: metabolites composition and development.

PubMed

Mulas, Gilberto; Galaffu, Maria Grazia; Pretti, Luca; Nieddu, Gianni; Mercenaro, Luca; Tonelli, Roberto; Anedda, Roberto

2011-02-09

The goal of this work was to study via NMR the unaltered metabolic profile of Sardinian Vermentino grape berry. Seven selections of Vermentino were harvested from the same vineyard. Berries were stored and extracted following an unbiased extraction protocol. Extracts were analyzed to investigate variability in metabolites concentration as a function of the clone, the position of berries in the bunch or growing area within the vineyard. Quantitative NMR and statistical analysis (PCA, correlation analysis, Anova) of the experimental data point out that, among the investigated sources of variation, the position of the berries within the bunch mainly influences the metabolic profile of berries, while the metabolic profile does not seem to be significantly influenced by growing area and clone. Significant variability of the amino acids such as arginine, proline, and organic acids (malic and citric) characterizes the rapid rearrangements of the metabolic profile in response to environmental stimuli. Finally, an application is described on the analysis of metabolite variation throughout the physiological development of berries.

Analysis of spatial patterns underlying the linkage between solar irradiance and near-surface air temperatures

NASA Astrophysics Data System (ADS)

Balling, Robert C.; Roy, Shouraseni Sen

2005-06-01

Many scientists have noted that global temperature anomalies were highly correlated with solar irradiance values until sometime in the 1970s, but since that time, the pronounced warming in the near-surface temperature record is not explained by variations or trends in solar receipt. In this investigation, spatial dimensions are explored in the relationship between irradiance and near-surface air temperatures. At the scale of individual 5° by 5° grid cells, the solar control on annual temperature variations is not statistically significant. When the temperature data are aggregated by 5° latitudinal bands, the solar - temperature connect is generally significant, and in every band, there is substantial evidence that a non-solar control has become dominant in recent decades. The buildup of greenhouse gases and/or some other global-scale feedback, such as widespread changes in atmospheric water vapor, emerge as potential explanations for the recent residual warming found in all latitudinal bands.

Population differentiation in the red-legged kittiwake (Rissa brevirostris) as revealed by mitochondrial DNA

USGS Publications Warehouse

Patirana, A.; Hatcher, S.A.; Friesen, Vicki L.

2002-01-01

Population decline in red-legged kittiwakes (Rissa brevirostris) over recent decades has necessitated the collection of information on the distribution of genetic variation within and among colonies for implementation of suitable management policies. Here we present a preliminary study of the extent of genetic structuring and gene flow among the three principal breeding locations of red-legged kittiwakes using the hypervariable Domain I of the mitochondrial control region. Genetic variation was high relative to other species of seabirds, and was similar among locations. Analysis of molecular variance indicated that population genetic structure was statistically significant, and nested clade analysis suggested that kittiwakes breeding on Bering Island maybe genetically isolated from those elsewhere. However, phylogeographic structure was weak. Although this analysis involved only a single locus and a small number of samples, it suggests that red-legged kittiwakes probably constitute a single evolutionary significant unit; the possibility that they constitute two management units requires further investigation.

A framework for the interpretation of de novo mutation in human disease

PubMed Central

Samocha, Kaitlin E.; Robinson, Elise B.; Sanders, Stephan J.; Stevens, Christine; Sabo, Aniko; McGrath, Lauren M.; Kosmicki, Jack A.; Rehnström, Karola; Mallick, Swapan; Kirby, Andrew; Wall, Dennis P.; MacArthur, Daniel G.; Gabriel, Stacey B.; dePristo, Mark; Purcell, Shaun M.; Palotie, Aarno; Boerwinkle, Eric; Buxbaum, Joseph D.; Cook, Edwin H.; Gibbs, Richard A.; Schellenberg, Gerard D.; Sutcliffe, James S.; Devlin, Bernie; Roeder, Kathryn; Neale, Benjamin M.; Daly, Mark J.

2014-01-01

Spontaneously arising (‘de novo’) mutations play an important role in medical genetics. For diseases with extensive locus heterogeneity – such as autism spectrum disorders (ASDs) – the signal from de novo mutations (DNMs) is distributed across many genes, making it difficult to distinguish disease-relevant mutations from background variation. We provide a statistical framework for the analysis of DNM excesses per gene and gene set by calibrating a model of de novo mutation. We applied this framework to DNMs collected from 1,078 ASD trios and – while affirming a significant role for loss-of-function (LoF) mutations – found no excess of de novo LoF mutations in cases with IQ above 100, suggesting that the role of DNMs in ASD may reside in fundamental neurodevelopmental processes. We also used our model to identify ~1,000 genes that are significantly lacking functional coding variation in non-ASD samples and are enriched for de novo LoF mutations identified in ASD cases. PMID:25086666

Spatial and Temporal Variation of Water Quality in the Bertam Catchment, Cameron Highlands, Malaysia.

PubMed

Rasul, M G; Islam, Mir Sujaul; Yunus, Rosli Bin Mohd; Mokhtar, Mazlin Bin; Alam, Lubna; Yahaya, F M

2017-12-01

  The spatio-temporal variability of water quality associated with anthropogenic activities was studied for the Bertam River and its main tributaries within the Bertam Catchment, Cameron Highlands, Malaysia. A number of physico-chemical parameters of collected samples were analyzed to evaluate their spatio-temporal variability. Nonparametric statistical analysis showed significant temporal and spatial differences (p < 0.05) in most of the parameters across the catchment. Parameters except dissolved oxygen and chemical oxygen demand displayed higher values in rainy season. The higher concentration of total suspended solids was caused by massive soil erosion and sedimentation. Seasonal variations in contaminant concentrations are largely affected by precipitation and anthropogenic influences. Untreated domestic wastewater discharge as well as agricultural runoff significantly influenced the water quality. Poor agricultural practices and development activities at slope areas also affected the water quality within the catchment. The analytical results provided a basis for protection of river environments and ecological restoration in mountainous Bertam Catchment.

Standards of Scientific Conduct: Disciplinary differences

PubMed Central

Kalichman, Michael; Sweet, Monica; Plemmons, Dena

2014-01-01

Teaching of responsible conduct of research is largely predicated on the assumption that there are accepted standards of conduct that can be taught. However there is little evidence of consensus in the scientific community about such standards, at least for the practices of authorship, collaboration, and data management. To assess whether such differences in standards are based on disciplinary differences, a survey, described previously, addressing standards, practices, and perceptions about teaching and learning was distributed in November 2010 to U.S. faculty from 50 graduate programs for the biomedical disciplines of microbiology, neuroscience, nursing, and psychology. Despite evidence of statistically significant differences across the four disciplines, actual differences were quite small. Stricter measures of effect size indicated practically significant disciplinary differences for fewer than 10% of the questions. This suggests that the variation in individual standards of practice within each discipline is at least as great as variation due to differences among disciplines. Therefore, the need for discipline-specific training may not be as important as sometimes thought. PMID:25256408

SNP-based heritability estimates of the personality dimensions and polygenic prediction of both neuroticism and major depression: findings from CONVERGE.

PubMed

Docherty, A R; Moscati, A; Peterson, R; Edwards, A C; Adkins, D E; Bacanu, S A; Bigdeli, T B; Webb, B T; Flint, J; Kendler, K S

2016-10-25

Biometrical genetic studies suggest that the personality dimensions, including neuroticism, are moderately heritable (~0.4 to 0.6). Quantitative analyses that aggregate the effects of many common variants have recently further informed genetic research on European samples. However, there has been limited research to date on non-European populations. This study examined the personality dimensions in a large sample of Han Chinese descent (N=10 064) from the China, Oxford, and VCU Experimental Research on Genetic Epidemiology study, aimed at identifying genetic risk factors for recurrent major depression among a rigorously ascertained cohort. Heritability of neuroticism as measured by the Eysenck Personality Questionnaire (EPQ) was estimated to be low but statistically significant at 10% (s.e.=0.03, P=0.0001). In addition to EPQ, neuroticism based on a three-factor model, data for the Big Five (BF) personality dimensions (neuroticism, openness, conscientiousness, extraversion and agreeableness) measured by the Big Five Inventory were available for controls (n=5596). Heritability estimates of the BF were not statistically significant despite high power (>0.85) to detect heritabilities of 0.10. Polygenic risk scores constructed by best linear unbiased prediction weights applied to split-half samples failed to significantly predict any of the personality traits, but polygenic risk for neuroticism, calculated with LDpred and based on predictive variants previously identified from European populations (N=171 911), significantly predicted major depressive disorder case-control status (P=0.0004) after false discovery rate correction. The scores also significantly predicted EPQ neuroticism (P=6.3 × 10 -6 ). Factor analytic results of the measures indicated that any differences in heritabilities across samples may be due to genetic variation or variation in haplotype structure between samples, rather than measurement non-invariance. Findings demonstrate that neuroticism can be significantly predicted across ancestry, and highlight the importance of studying polygenic contributions to personality in non-European populations.

Anterior temporal lobes and hippocampal formations: normative volumetric measurements from MR images in young adults.

PubMed

Jack, C R; Twomey, C K; Zinsmeister, A R; Sharbrough, F W; Petersen, R C; Cascino, G D

1989-08-01

Volumes of the right and left anterior temporal lobes and hippocampal formations were measured from magnetic resonance images in 52 healthy volunteers, aged 20-40 years. Subjects were selected by age, sex, and handedness to evaluate possible effect of these variables. Data were normalized for variation in total intracranial volume between individuals. Right-left asymmetry in the volumes of the anterior temporal lobes and hippocampal formations was a normal finding. The anterior temporal lobe of the non-dominant (right) hemisphere was larger than the left by a small (mean right-left difference, 2.3 cm3) but statistically significant amount (P less than .005) in right-handed subjects. No significant effect of age or sex was seen in normalized right or left anterior temporal lobe volume. The right hippocampal formation was larger than the left for all subjects by a small (mean right-left difference, 0.3 cm3) but statistically significant amount (P less than .001). No effect of age, sex, or handedness was seen in normalized hippocampal formation volumes.

On statistical analysis of factors affecting anthocyanin extraction from Ixora siamensis

NASA Astrophysics Data System (ADS)

Mat Nor, N. A.; Arof, A. K.

2016-10-01

This study focused on designing an experimental model in order to evaluate the influence of operative extraction parameters employed for anthocyanin extraction from Ixora siamensis on CIE color measurements (a*, b* and color saturation). Extractions were conducted at temperatures of 30, 55 and 80°C, soaking time of 60, 120 and 180 min using acidified methanol solvent with different trifluoroacetic acid (TFA) contents of 0.5, 1.75 and 3% (v/v). The statistical evaluation was performed by running analysis of variance (ANOVA) and regression calculation to investigate the significance of the generated model. Results show that the generated regression models adequately explain the data variation and significantly represented the actual relationship between the independent variables and the responses. Analysis of variance (ANOVA) showed high coefficient determination values (R2) of 0.9687 for a*, 0.9621 for b* and 0.9758 for color saturation, thus ensuring a satisfactory fit of the developed models with the experimental data. Interaction between TFA content and extraction temperature exhibited to the highest significant influence on CIE color parameter.

Heritable Variation for Sex Ratio under Environmental Sex Determination in the Common Snapping Turtle (Chelydra Serpentina)

PubMed Central

Janzen, F. J.

1992-01-01

The magnitude of quantitative genetic variation for primary sex ratio was measured in families extracted from a natural population of the common snapping turtle (Chelydra serpentina), which possesses temperature-dependent sex determination (TSD). Eggs were incubated at three temperatures that produced mixed sex ratios. This experimental design provided estimates of the heritability of sex ratio in multiple environments and a test of the hypothesis that genotype X environment (G X E) interactions may be maintaining genetic variation for sex ratio in this population of C. serpentina. Substantial quantitative genetic variation for primary sex ratio was detected in all experimental treatments. These results in conjunction with the occurrence of TSD in this species provide support for three critical assumptions of Fisher's theory for the microevolution of sex ratio. There were statistically significant effects of family and incubation temperature on sex ratio, but no significant interaction was observed. Estimates of the genetic correlations of sex ratio across environments were highly positive and essentially indistinguishable from +1. These latter two findings suggest that G X E interaction is not the mechanism maintaining genetic variation for sex ratio in this system. Finally, although substantial heritable variation exists for primary sex ratio of C. serpentina under constant temperatures, estimates of the effective heritability of primary sex ratio in nature are approximately an order of magnitude smaller. Small effective heritability and a long generation time in C. serpentina imply that evolution of sex ratios would be slow even in response to strong selection by, among other potential agents, any rapid and/or substantial shifts in local temperatures, including those produced by changes in the global climate. PMID:1592234

Untangling individual variation in natural populations: ecological, genetic and epigenetic correlates of long-term inequality in herbivory.

PubMed

Herrera, C M; Bazaga, P

2011-04-01

Individual variation in ecologically important features of organisms is a crucial element in ecology and evolution, yet disentangling its underlying causes is difficult in natural populations. We applied a genomic scan approach using amplified fragment length polymorphism (AFLP) markers to quantify the genetic basis of long-term individual differences in herbivory by mammals at a wild population of the violet Viola cazorlensis monitored for two decades. In addition, methylation-sensitive amplified polymorphism (MSAP) analyses were used to investigate the association between browsing damage and epigenetic characteristics of individuals, an aspect that has been not previously explored for any wild plant. Structural equation modelling was used to identify likely causal structures linking genotypes, epigenotypes and herbivory. Individuals of V. cazorlensis differed widely in the incidence of browsing mammals over the 20-year study period. Six AFLP markers (1.6% of total) were significantly related to herbivory, accounting altogether for 44% of population-wide variance in herbivory levels. MSAP analyses revealed considerable epigenetic variation among individuals, and differential browsing damage was significantly related to variation in multilocus epigenotypes. In addition, variation across plants in epigenetic characteristics was related to variation in several herbivory-related AFLP markers. Statistical comparison of alternative causal models suggested that individual differences in herbivory are the outcome of a complex causal structure where genotypes and epigenotypes are interconnected and have direct and indirect effects on herbivory. Insofar as methylation states of MSAP markers influential on herbivory are transgenerationally heritable, herbivore-driven evolutionary changes at the study population will involve correlated changes in genotypic and epigenotypic distributions. © 2011 Blackwell Publishing Ltd.

Soil coring at multiple field environments can directly quantify variation in deep root traits to select wheat genotypes for breeding.

PubMed

Wasson, A P; Rebetzke, G J; Kirkegaard, J A; Christopher, J; Richards, R A; Watt, M

2014-11-01

We aim to incorporate deep root traits into future wheat varieties to increase access to stored soil water during grain development, which is twice as valuable for yield as water captured at younger stages. Most root phenotyping efforts have been indirect studies in the laboratory, at young plant stages, or using indirect shoot measures. Here, soil coring to 2 m depth was used across three field environments to directly phenotype deep root traits on grain development (depth, descent rate, density, length, and distribution). Shoot phenotypes at coring included canopy temperature depression, chlorophyll reflectance, and green leaf scoring, with developmental stage, biomass, and yield. Current varieties, and genotypes with breeding histories and plant architectures expected to promote deep roots, were used to maximize identification of variation due to genetics. Variation was observed for deep root traits (e.g. 111.4-178.5cm (60%) for depth; 0.09-0.22cm/°C day (144%) for descent rate) using soil coring in the field environments. There was significant variation for root traits between sites, and variation in the relative performance of genotypes between sites. However, genotypes were identified that performed consistently well or poorly at both sites. Furthermore, high-performing genotypes were statistically superior in root traits than low-performing genotypes or commercial varieties. There was a weak but significant negative correlation between green leaf score (-0.5), CTD (0.45), and rooting depth and a positive correlation for chlorophyll reflectance (0.32). Shoot phenotypes did not predict other root traits. This study suggests that field coring can directly identify variation in deep root traits to speed up selection of genotypes for breeding programmes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Relationship Between Gender, Age, and Weight and the Serum Ionized Calcium Variations in Dog Periodontal Disease Evolution.

PubMed

Carreira, L Miguel; Dias, Daniela; Azevedo, Pedro

2015-06-01

To analyze the relationships between gender, age, weight, and variations in the levels of serum ionized calcium ([iCa(2+)]) during periodontal disease (PD) evolution. In this study, dogs (n = 50) were divided into 5 groups according to the stage of PD: G0 (no PD), G1 (gingivitis), G2 (initial periodontitis), G3 (moderate periodontitis), and G4 (severe periodontitis). Statistically significant correlations were observed between age, [iCa(2+)] levels, and PD stage. Older dogs had lower [iCa(2+)] levels and more advanced PD stages (high positive correlation), and their body weight decreased as PD developed (negative correlation). Lower [iCa(2+)] values were associated with more severe PD. Copyright © 2015 Elsevier Inc. All rights reserved.

Does actually mean chromosome number increase with latitude in vascular plants? An answer from the comparison of Italian, Slovak and Polish floras.

PubMed

Peruzzi, Lorenzo; Góralski, Grzegorz; Joachimiak, Andrzej J; Bedini, Gianni

2012-01-01

WE COMPARED CHROMOSOME NUMBER (CN) VARIATION AMONG VASCULAR FLORAS OF THREE DIFFERENT COUNTRIES WITH INCREASING LATITUDE IN THE BOREAL HEMISPHERE: Italy, Slovakia, Poland. Aim of the study was to verify whether the patterns of CN variation parallel the differences in latitudinal ranges. The three datasets comprised 3426 (Italy), 3493 (Slovakia) and 1870 (Poland) distinct cytotypes. Standard statistics (ANOVA, Kruskal-Wallis tests) evidenced significant differences among the three countries, mean CN increasing together with latitude. On the contrary, an inverse relation (r = -1) was evidenced among the frequency of odd CNs and latitude. Our results show that the hypothesis of a polyploid increase proportional with distance from the Equator seems to be confirmed, when territories from the same hemisphere are compared.

An Alternate, Egg-Free Radiolabeled Meal Formulation for Gastric-Emptying Scintigraphy.

PubMed

Garrigue, Philippe; Bodin-Hullin, Aurore; Gonzalez, Sandra; Sala, Quentin; Guillet, Benjamin

2017-07-01

Tc-radiolabeled scrambled eggs (SEs) are most often used as the ingested solid phase for gastric-emptying scintigraphy, leading egg-reluctant patients to avoid the examination. We formulated and validated 2 egg-free alternate meals, in the absence of any commercialized formulation: chocolate mug cake (MC) and scrambled tofu (ST). Six healthy volunteers underwent gastric-emptying scintigraphy after ingesting Tc-radiolabeled MC, ST, or SE. Gastric retention indexes did not change significantly between formulations (% of overtime variation to SE: MC 7.75% ± 7.1%, ST 7.17% ± 5.8%; P = 0.6618, not statistically significant), suggesting MC and ST as interesting egg-free alternatives.

Global DNA cytosine methylation as an evolving trait: phylogenetic signal and correlated evolution with genome size in angiosperms

PubMed Central

Alonso, Conchita; Pérez, Ricardo; Bazaga, Pilar; Herrera, Carlos M.

2015-01-01

DNA cytosine methylation is a widespread epigenetic mechanism in eukaryotes, and plant genomes commonly are densely methylated. Genomic methylation can be associated with functional consequences such as mutational events, genomic instability or altered gene expression, but little is known on interspecific variation in global cytosine methylation in plants. In this paper, we compare global cytosine methylation estimates obtained by HPLC and use a phylogenetically-informed analytical approach to test for significance of evolutionary signatures of this trait across 54 angiosperm species in 25 families. We evaluate whether interspecific variation in global cytosine methylation is statistically related to phylogenetic distance and also whether it is evolutionarily correlated with genome size (C-value). Global cytosine methylation varied widely between species, ranging between 5.3% (Arabidopsis) and 39.2% (Narcissus). Differences between species were related to their evolutionary trajectories, as denoted by the strong phylogenetic signal underlying interspecific variation. Global cytosine methylation and genome size were evolutionarily correlated, as revealed by the significant relationship between the corresponding phylogenetically independent contrasts. On average, a ten-fold increase in genome size entailed an increase of about 10% in global cytosine methylation. Results show that global cytosine methylation is an evolving trait in angiosperms whose evolutionary trajectory is significantly linked to changes in genome size, and suggest that the evolutionary implications of epigenetic mechanisms are likely to vary between plant lineages. PMID:25688257

Homogeneity and variation of donor doping in Verneuil-grown SrTiO3:Nb single crystals

PubMed Central

Rodenbücher, C.; Luysberg, M.; Schwedt, A.; Havel, V.; Gunkel, F.; Mayer, J.; Waser, R.

2016-01-01

The homogeneity of Verneuil-grown SrTiO3:Nb crystals was investigated. Due to the fast crystal growth process, inhomogeneities in the donor dopant distribution and variation in the dislocation density are expected to occur. In fact, for some crystals optical studies show variations in the density of Ti3+ states on the microscale and a cluster-like surface conductivity was reported in tip-induced resistive switching studies. However, our investigations by TEM, EDX mapping, and 3D atom probe reveal that the Nb donors are distributed in a statistically random manner, indicating that there is clearly no inhomogeneity on the macro-, micro-, and nanoscale in high quality Verneuil-grown crystals. In consequence, the electronic transport in the bulk of donor-doped crystals is homogeneous and it is not significantly channelled by extended defects such as dislocations which justifies using this material, for example, as electronically conducting substrate for epitaxial oxide film growth. PMID:27577508

Effect of Cultivar and Cultivation Year on the Metabolite Profile of Onion Bulbs ( Allium cepa L.).

PubMed

Böttcher, Christoph; Krähmer, Andrea; Stürtz, Melanie; Widder, Sabine; Schulz, Hartwig

2018-03-28

This study investigated the variation of metabolite profiles of onion bulbs ( Allium cepa L.) depending on genetic and environmental factors. Nine onion cultivars ("Corrado", "Cupido", "Forum", "Hytech", "Picador", "Redlight", "Snowpack", "Stardust", "Sturon") with different scale color and dry matter content were grown in a two-year field trial. Using a recently established metabolite profiling approach based on liquid chromatography-coupled electrospray ionization quadrupole time-of-flight mass spectrometry, 106 polar and semipolar metabolites which belong to compound classes determining nutritional, sensory, and technological quality of onion bulbs such as saccharides, flavonoids, S-substitued cysteine conjugates, amino acids, and derived γ-glutamyl peptides were relatively quantitated in parallel. Statistical analyses of the obtained data indicated that depending on the compound class genetic and environmental factors differently contributed to variation of metabolite levels. For saccharides and flavonoids the genetic factor was the major source of variation, whereas for cysteine sulfoxides, amino acids, and peptides both genetic and environmental factors had a significant impact on corresponding metabolite levels.

Sea surface temperature 1871-2099 in 14 cells around the United Kingdom.

PubMed

Sheppard, Charles

2004-07-01

Monthly sea surface temperature is provided for 14 locations around the UK for a 230 year period. These series are derived from the HadISST1 data set for historical time (1871-1999) and from the HadCM3 climate model for predicted SST (1950-2099). Two adjustments of the forecast data sets are needed to produce confluent SST series: the 50 year overlap is used for a gross adjustment, and a statistical scaling on the forecast data ensures that annual variations in forecast data match those of historical data. These monthly SST series are available on request. The overall rise in SST over time is clear for all sites, commencing in the last quarter of the 20th century. Apart from expected trends of overall warmer mean SST with more southerly latitudes and overall cooler mean SST towards the East, more interesting statistically significant general trends include a greater decadal rate of rise from warmer starting conditions. Annual temperature variation is not affected by absolute temperature, but is markedly greater towards the East. There is no correlation of annual range of SST with latitude, or with present SST values.

Effect of Control Mode and Test Rate on the Measured Fracture Toughness of Advanced Ceramics

NASA Technical Reports Server (NTRS)

Hausmann, Bronson D.; Salem, Jonathan A.

2018-01-01

The effects of control mode and test rate on the measured fracture toughness of ceramics were evaluated by using chevron-notched flexure specimens in accordance with ASTM C1421. The use of stroke control gave consistent results with about 2% (statistically insignificant) variation in measured fracture toughness for a very wide range of rates (0.005 to 0.5 mm/min). Use of strain or crack mouth opening displacement (CMOD) control gave approx. 5% (statistically significant) variation over a very wide range of rates (1 to 80 µm/m/s), with the measurements being a function of rate. However, the rate effect was eliminated by use of dry nitrogen, implying a stress corrosion effect rather than a stability effect. With the use of a nitrogen environment during strain controlled tests, fracture toughness values were within about 1% over a wide range of rates (1 to 80 micons/m/s). CMOD or strain control did allow stable crack extension well past maximum force, and thus is preferred for energy calculations. The effort is being used to confirm recommendations in ASTM Test Method C1421 on fracture toughness measurement.

Explaining fruit and vegetable intake using a consumer marketing tool.

PubMed

Della, Lindsay J; Dejoy, David M; Lance, Charles E

2009-10-01

In response to calls to reinvent the 5 A Day fruit and vegetable campaign, this study assesses the utility of VALS, a consumer-based audience segmentation tool that divides the U.S. population into groups leading similar lifestyles. The study examines whether the impact of theory of planned behavior (TPB) constructs varies across VALS groups in a cross-sectional sample of 1,588 U.S. adults. In a multigroup structural equation model, the VALS audience group variable moderated latent TPB relationships. Attitudes, subjective norms, and perceived behavioral control explained 57% to 70% of the variation in intention to eat fruit and vegetables across 5 different VALS groups. Perceived behavioral control and intention also predicted self-reported consumption behavior (R2 = 20% to 71% across VALS groups). Bivariate z tests were calculated to determine statistical differences in parameter estimates across groups. Nine of the bivariate z tests were statistically significant (p < or = .04), with standardized coefficients ranging from .05 to .70. These findings confirm the efficacy of using the TPB to explain variation in fruit and vegetable consumption as well as the validity of using a consumer-based algorithm to segment audiences for fruit and vegetable consumption messaging.

The genetic basis of female multiple mating in a polyandrous livebearing fish

PubMed Central

Evans, Jonathan P; Gasparini, Clelia

2013-01-01

The widespread occurrence of female multiple mating (FMM) demands evolutionary explanation, particularly in the light of the costs of mating. One explanation encapsulated by “good sperm” and “sexy-sperm” (GS-SS) theoretical models is that FMM facilitates sperm competition, thus ensuring paternity by males that pass on genes for elevated sperm competitiveness to their male offspring. While support for this component of GS-SS theory is accumulating, a second but poorly tested assumption of these models is that there should be corresponding heritable genetic variation in FMM – the proposed mechanism of postcopulatory preferences underlying GS-SS models. Here, we conduct quantitative genetic analyses on paternal half-siblings to test this component of GS-SS theory in the guppy (Poecilia reticulata), a freshwater fish with some of the highest known rates of FMM in vertebrates. As with most previous quantitative genetic analyses of FMM in other species, our results reveal high levels of phenotypic variation in this trait and a correspondingly low narrow-sense heritability (h2 = 0.11). Furthermore, although our analysis of additive genetic variance in FMM was not statistically significant (probably owing to limited statistical power), the ensuing estimate of mean-standardized additive genetic variance (IA = 0.7) was nevertheless relatively low compared with estimates published for life-history traits across a broad range of taxa. Our results therefore add to a growing body of evidence that FMM is characterized by relatively low additive genetic variation, thus apparently contradicting GS-SS theory. However, we qualify this conclusion by drawing attention to potential deficiencies in most designs (including ours) that have tested for genetic variation in FMM, particularly those that fail to account for intersexual interactions that underlie FMM in many systems. PMID:23403856

Seasonal Variation of Total Mercury Burden in the American Alligator (Alligator Mississippiensis) at Merritt Island National Wildlife Refuge (MINWR), Florida

NASA Technical Reports Server (NTRS)

Nilsen, Frances M.; Dorsey, Jonathan E.; Long, Stephen E.; Schock, Tracey B.; Bowden, John A.; Lowers, Russell H.; Guillette, Louis J., Jr.

2016-01-01

Seasonal variation of mercury (Hg) is not well studied in free-ranging wildlife. Atmospheric deposition patterns of Hg have been studied in detail and have been modeled for both global and specific locations with great accuracy and correlates to environment impact. However, monitoring these trends in wildlife is complicated due to local environmental parameters (e.g., rainfall, humidity, pH, bacterial composition) that can affect the transformation of atmospheric Hg to the biologically available forms. Here, we utilized an abundant and healthy population of American alligators (Alligator mississippiensis) at Merritt Island National Wildlife Refuge (MINWR), FL, and assessed Hg burden in whole blood samples over a span of 7 years (2007 2014; n 174) in an effort to assess seasonal variation of total [Hg]. While the majority of this population is assumed healthy, 18 individuals with low body mass indices (BMI, defined in this study) were captured throughout the 7 year sampling period. These individual alligators exhibited [Hg] that were not consistent with the observed overall seasonal [Hg] variation, and were statistically different from the healthy population of alligators. The alligators with low BMI had elevated concentrations of Hg compared to their age/sex/season matched counterparts with normal BMI. Statistically significant differences were found between the winter and spring seasons for animals with normal BMI. The data in this report supports the conclusion that organismal total [Hg] do fluctuate directly with seasonal deposition rates as well as other seasonal environmental parameters, such as average rainfall and prevailing wind direction. This study highlights the unique environment of MINWR to permit annual assessment of apex predators, such as the American alligator, to determine detailed environmental impact of contaminants of concern.

The energetic cost of walking: a comparison of predictive methods.

PubMed

Kramer, Patricia Ann; Sylvester, Adam D

2011-01-01

The energy that animals devote to locomotion has been of intense interest to biologists for decades and two basic methodologies have emerged to predict locomotor energy expenditure: those based on metabolic and those based on mechanical energy. Metabolic energy approaches share the perspective that prediction of locomotor energy expenditure should be based on statistically significant proxies of metabolic function, while mechanical energy approaches, which derive from many different perspectives, focus on quantifying the energy of movement. Some controversy exists as to which mechanical perspective is "best", but from first principles all mechanical methods should be equivalent if the inputs to the simulation are of similar quality. Our goals in this paper are 1) to establish the degree to which the various methods of calculating mechanical energy are correlated, and 2) to investigate to what degree the prediction methods explain the variation in energy expenditure. We use modern humans as the model organism in this experiment because their data are readily attainable, but the methodology is appropriate for use in other species. Volumetric oxygen consumption and kinematic and kinetic data were collected on 8 adults while walking at their self-selected slow, normal and fast velocities. Using hierarchical statistical modeling via ordinary least squares and maximum likelihood techniques, the predictive ability of several metabolic and mechanical approaches were assessed. We found that all approaches are correlated and that the mechanical approaches explain similar amounts of the variation in metabolic energy expenditure. Most methods predict the variation within an individual well, but are poor at accounting for variation between individuals. Our results indicate that the choice of predictive method is dependent on the question(s) of interest and the data available for use as inputs. Although we used modern humans as our model organism, these results can be extended to other species.

Chromosome number variation in two antipodean floras.

PubMed

Peruzzi, Lorenzo; Dawson, Murray I; Bedini, Gianni

2011-01-01

We compared chromosome number (CN) variation in the nearly antipodean Italian and New Zealand floras to verify (i) whether patterns of variation reflect their similar latitudinal ranges or their different biogeographic/taxonomic contexts, (ii) if any differences are equally distributed across major taxa/lineages and (iii) if the frequency, number and taxonomic distribution of B-chromosomes differ between the two countries. We compared two datasets comprising 3426 (Italy) and 2525 (New Zealand) distinct cytotypes. We also compared a subset based on taxonomic orders and superimposed them onto a phylogeny of vascular plants. We used standard statistics, histograms, and either analysis of variance or Kruskal-Wallis tests to analyse the data. Mean CN of the vascular New Zealand flora is about twice that of Italy. For most orders, mean CN values for New Zealand are higher than those of the Italian flora and the differences are statistically significant. Further differences in CN variation among the orders and main clades that we studied, irrespective of geographical distinctions, are revealed. No correlation was found between chromosome and B-chromosome number. Mean CN of the whole New Zealand dataset is about twice that of the Italian flora. This suggests that extensive polyploidization played a major role in the evolution of the New Zealand vascular flora that is characterized by a rate of high endemism. Our results show that the hypothesis of a polyploid increase proportional to distance from the Equator cannot be applied to territories with the same latitudinal ranges but placed in different hemispheres. We suggest that bioclimatic gradients, rather than or in addition to latitudinal gradients, might account for a polyploidy increase. Our data also suggest that any adaptive role of B-chromosomes at geographic scale may be sought in their frequency rather than in their number.

Chromosome number variation in two antipodean floras

PubMed Central

Peruzzi, Lorenzo; Dawson, Murray I.; Bedini, Gianni

2011-01-01

Background and aims We compared chromosome number (CN) variation in the nearly antipodean Italian and New Zealand floras to verify (i) whether patterns of variation reflect their similar latitudinal ranges or their different biogeographic/taxonomic contexts, (ii) if any differences are equally distributed across major taxa/lineages and (iii) if the frequency, number and taxonomic distribution of B-chromosomes differ between the two countries. Methodology We compared two datasets comprising 3426 (Italy) and 2525 (New Zealand) distinct cytotypes. We also compared a subset based on taxonomic orders and superimposed them onto a phylogeny of vascular plants. We used standard statistics, histograms, and either analysis of variance or Kruskal–Wallis tests to analyse the data. Principal results Mean CN of the vascular New Zealand flora is about twice that of Italy. For most orders, mean CN values for New Zealand are higher than those of the Italian flora and the differences are statistically significant. Further differences in CN variation among the orders and main clades that we studied, irrespective of geographical distinctions, are revealed. No correlation was found between chromosome and B-chromosome number. Conclusions Mean CN of the whole New Zealand dataset is about twice that of the Italian flora. This suggests that extensive polyploidization played a major role in the evolution of the New Zealand vascular flora that is characterized by a rate of high endemism. Our results show that the hypothesis of a polyploid increase proportional to distance from the Equator cannot be applied to territories with the same latitudinal ranges but placed in different hemispheres. We suggest that bioclimatic gradients, rather than or in addition to latitudinal gradients, might account for a polyploidy increase. Our data also suggest that any adaptive role of B-chromosomes at geographic scale may be sought in their frequency rather than in their number. PMID:22476490

Variation in caesarean section rates in the US: outliers, damned outliers, and statistics.

PubMed

Smith, Gordon C S

2014-10-01

Gordon C. Smith discusses the study by Katy Kozhimannil and colleagues that examines variations in cesarean section rates in the US and argues for the need for high-quality routine data collection to better understand the reasons for these variations. Please see later in the article for the Editors' Summary.

Defining the ecological hydrology of Taiwan Rivers using multivariate statistical methods

NASA Astrophysics Data System (ADS)

Chang, Fi-John; Wu, Tzu-Ching; Tsai, Wen-Ping; Herricks, Edwin E.

2009-09-01

SummaryThe identification and verification of ecohydrologic flow indicators has found new support as the importance of ecological flow regimes is recognized in modern water resources management, particularly in river restoration and reservoir management. An ecohydrologic indicator system reflecting the unique characteristics of Taiwan's water resources and hydrology has been developed, the Taiwan ecohydrological indicator system (TEIS). A major challenge for the water resources community is using the TEIS to provide environmental flow rules that improve existing water resources management. This paper examines data from the extensive network of flow monitoring stations in Taiwan using TEIS statistics to define and refine environmental flow options in Taiwan. Multivariate statistical methods were used to examine TEIS statistics for 102 stations representing the geographic and land use diversity of Taiwan. The Pearson correlation coefficient showed high multicollinearity between the TEIS statistics. Watersheds were separated into upper and lower-watershed locations. An analysis of variance indicated significant differences between upstream, more natural, and downstream, more developed, locations in the same basin with hydrologic indicator redundancy in flow change and magnitude statistics. Issues of multicollinearity were examined using a Principal Component Analysis (PCA) with the first three components related to general flow and high/low flow statistics, frequency and time statistics, and quantity statistics. These principle components would explain about 85% of the total variation. A major conclusion is that managers must be aware of differences among basins, as well as differences within basins that will require careful selection of management procedures to achieve needed flow regimes.

Ethnicity and Psychiatric Disorders

PubMed Central

Hawes, Armani M.; Axinn, William G.; Ghimire, Dirgha J.

2016-01-01

Psychiatric disorders are one of the leading causes of disease-related disability in the world today. However, little is known about the ethnic variation of these disorders within populations. This is especially true in contexts outside of the United States and the European Diaspora. This study provides new evidence from South Asia on ethnic differences in Major Depressive Episode, Major Depressive Disorder, Panic Attack, Panic Disorder, Post-Traumatic Stress Disorder, and Intermittent Explosive Disorder. We use data from 400 adult interviews conducted in Nepal in a controlled comparison design as a case study. We use a series of multilevel logistic regression models to predict ethnic group differences in psychiatric disorders and episodes with measures from clinically validated World Mental Health survey instruments. Compared to the Brahmin/Chhetri group, we found historically excluded Dalits had statistically significantly higher odds of almost all psychiatric disorders and episodes. We also found that historically resilient Janajatis had statistically significantly lower odds of being diagnosed with PTSD than the majority Brahmin/Chhetri group. We also found no significant gender difference in MDD or MDE. Psychiatric disorders and episodes vary significantly by ethnicity within a rural Asian population, but gender differences are small. PMID:28824961

Testing the Relationships between Diversification, Species Richness, and Trait Evolution.

PubMed

Kozak, Kenneth H; Wiens, John J

2016-11-01

Understanding which traits drive species diversification is essential for macroevolutionary studies and to understand patterns of species richness among clades. An important tool for testing if traits influence diversification is to estimate rates of net diversification for each clade, and then test for a relationship between traits and diversification rates among clades. However, this general approach has become very controversial. Numerous papers have now stated that it is inappropriate to analyze net diversification rates in groups in which clade richness is not positively correlated with clade age. Similarly, some have stated that variation in net diversification rates does not explain variation in species richness patterns among clades across the Tree of Life. Some authors have also suggested that strong correlations between richness and diversification rates are a statistical artifact and effectively inevitable. If this latter point is true, then correlations between richness and diversification rates would be uninformative (or even misleading) for identifying how much variation in species richness among clades is explained by variation in net diversification rates. Here, we use simulations (based on empirical data for plethodontid salamanders) to address three main questions. First, how is variation in net diversification rates among clades related to the relationship between clade age and species richness? Second, how accurate are these net diversification rate estimators, and does the age-richness relationship have any relevance to their accuracy? Third, is a relationship between species richness and diversification rates an inevitable, statistical artifact? Our simulations show that strong, positive age-richness relationships arise when diversification rates are invariant among clades, whereas realistic variation in diversification rates among clades frequently disrupts this relationship. Thus, a significant age-richness relationship should not be a requirement for utilizing net diversification rates in macroevolutionary studies. Moreover, we find no difference in the accuracy of net diversification rate estimators between conditions in which there are strong, positive relationships between clade age and richness and conditions in which these strong relationships are absent. We find that net diversification rate estimators are reasonably accurate under many conditions (true and estimated rates are strongly corrrelated, and typically differ by ∼10-20%), but become more accurate when clades are older and less accurate when using incorrect assumptions about extinction. We also find that significant relationships between richness and diversification rates fail to arise under many conditions, especially when there are faster rates in younger clades. Therefore, a significant relationship between richness and diversification rates is not inevitable. Given this latter result, we suggest that relationships between richness and diversification should be tested for when attempting to explain the causes of richness patterns, to avoid potential misinterpretations (e.g., high diversification rates associated with low-richness clades). Similarly, our results also provide some support for previous studies suggesting that variation in diversification rates might explain much of the variation in species richness among major clades, based on strong relationships between clade richness and diversification rates. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Global Fire Trends from Satellite ATSR Instrument Series

NASA Astrophysics Data System (ADS)

Arino, Olivier; Casadio, Stefano; Serpe, Danilo

2010-12-01

Global night-time fire counts for the years from 1995 to 2009 have been obtained by using the latest version of Along Track Scanning Radiometer TOA radiance products (level 1), and related trends have been estimated. Possible biases due to cloud coverage variations have been assumed to be negligible. The sampling number (acquisition frequency) has also been analysed and proved not to influence our results. Global night-time fire trends have been evaluated by inspecting the time series of hot spots aggregated a) at 2°x2° scale; b) at district/country/region/continent scales, and c) globally. The statistical significance of the estimated trend parameters has been verified by means of the Mann-Kendal test. Results indicate that no trends in the absolute number of spots can be identified at the global scale, that there has been no appreciable shift in the fire season during the last fourteen years, and that statistically significant positive and negative trends are only found when data are aggregated at smaller scales.

Performance evaluation of three computed radiography systems using methods recommended in American Association of Physicists in Medicine Report 93

PubMed Central

Muhogora, Wilbroad; Padovani, Renato; Bonutti, Faustino; Msaki, Peter; Kazema, R.

2011-01-01

The performances of three clinical computed radiography (CR) systems, (Agfa CR 75 (with CRMD 4.0 image plates), Kodak CR 850 (with Kodak GP plates) and Kodak CR 850A (with Kodak GP plates)) were evaluated using six tests recommended in American Association of Physicists in Medicine Report 93. The results indicated variable performances with majority being within acceptable limits. The variations were mainly attributed to differences in detector formulations, plate readers’ characteristics, and aging effects. The differences of the mean low contrast scores between the imaging systems for three observers were statistically significant for Agfa and Kodak CR 850A (P=0.009) and for Kodak CR systems (P=0.006) probably because of the differences in ages. However, the differences were not statistically significant between Agfa and Kodak CR 850 (P=0.284) suggesting similar perceived image quality. The study demonstrates the need to implement quality control program regularly. PMID:21897559

Performance evaluation of three computed radiography systems using methods recommended in American Association of Physicists in Medicine Report 93.

PubMed

Muhogora, Wilbroad; Padovani, Renato; Bonutti, Faustino; Msaki, Peter; Kazema, R

2011-07-01

The performances of three clinical computed radiography (CR) systems, (Agfa CR 75 (with CRMD 4.0 image plates), Kodak CR 850 (with Kodak GP plates) and Kodak CR 850A (with Kodak GP plates)) were evaluated using six tests recommended in American Association of Physicists in Medicine Report 93. The results indicated variable performances with majority being within acceptable limits. The variations were mainly attributed to differences in detector formulations, plate readers' characteristics, and aging effects. The differences of the mean low contrast scores between the imaging systems for three observers were statistically significant for Agfa and Kodak CR 850A (P=0.009) and for Kodak CR systems (P=0.006) probably because of the differences in ages. However, the differences were not statistically significant between Agfa and Kodak CR 850 (P=0.284) suggesting similar perceived image quality. The study demonstrates the need to implement quality control program regularly.

Genetic stock assessment of spawning arctic cisco (Coregonus autumnalis) populations by flow cytometric determination of DNA content.

PubMed

Lockwood, S F; Bickham, J W

1991-01-01

Intraspecific variation in cellular DNA content was measured in five Coregonus autumnalis spawning populations from the Mackenzie River drainage, Canada, using flow cytometry. The rivers assayed were the Peel, Arctic Red, Mountain, Carcajou, and Liard rivers. DNA content was determined from whole blood preparations of fish from all rivers except the Carcajou, for which kidney tissue was used. DNA content measurements of kidney and blood preparations of the same fish from the Mountain River revealed statistically indistinguishable results. Mosaicism was found in blood preparations from the Peel, Arctic Red, Mountain, and Liard rivers, but was not observed in kidney tissue preparations from the Mountain or Carcajou rivers. The Liard River sample had significantly elevated mean DNA content relative to the other four samples; all other samples were statistically indistinguishable. Significant differences in mean DNA content among spawning stocks of a single species reinforces the need for adequate sample sizes of both individuals and populations when reporting "C" values for a particular species.

A multivariate auto-regressive combined-harmonics analysis and its application to ozone time series data

NASA Astrophysics Data System (ADS)

Yang, Eun-Su

2001-07-01

A new statistical approach is used to analyze Dobson Umkehr layer-ozone measurements at Arosa for 1979-1996 and Total Ozone Mapping Spectrometer (TOMS) Version 7 zonal mean ozone for 1979-1993, accounting for stratospheric aerosol optical depth (SAOD), quasi-biennial oscillation (QBO), and solar flux effects. A stepwise regression scheme selects statistically significant periodicities caused by season, SAOD, QBO, and solar variations and filters them out. Auto-regressive (AR) terms are included in ozone residuals and time lags are assumed for the residuals of exogenous variables. Then, the magnitudes of responses of ozone to the SAOD, QBO, and solar index (SI) series are derived from the stationary time series of the residuals. These Multivariate Auto-Regressive Combined Harmonics (MARCH) processes possess the following significant advantages: (1)the ozone trends are estimated more precisely than the previous methods; (2)the influences of the exogenous SAOD, QBO, and solar variations are clearly separated at various time lags; (3)the collinearity of the exogenous variables in the regression is significantly reduced; and (4)the probability of obtaining misleading correlations between ozone and exogenous times series is reduced. The MARCH results indicate that the Umkehr ozone response to SAOD (not a real ozone response but rather an optical interference effect), QBO, and solar effects is driven by combined dynamical radiative-chemical processes. These results are independently confirmed using the revised Standard models that include aerosol and solar forcing mechanisms with all possible time lags but not by the Standard model when restricted to a zero time lag in aerosol and solar ozone forcings. As for Dobson Umkehr ozone measurements at Arosa, the aerosol effects are most significant in layers 8, 7, and 6 with no time lag, as is to be expected due to the optical contamination of Umkehr measurements by SAOD. The QBO and solar UV effects appear in all layers 4-8, and in total ozone. In order to account for annual modulation of the equatorial winds that affects ozone at midlatitudes, a new QBO proxy is selected and applied to the Dobson Umkehr measurements at Arosa. The QBO proxy turns out to be more effective to filter the modulated ozone signals at midlatitudes than the mostly used QBO proxy, the Singapore winds at 30 mb. A statistically significant negative phase relationship is found between solar UV variation and ozone response, especially in layer 4, implying dynamical effects of solar variations on ozone at midlatitudes. Linear negative trends in ozone of -7.8 +/- 1.1 and -5.2 +/- 1.4 [%/decade +/- 2σ] are calculated in layers 7 (~35 km) and 8 (~40 km), respectively, for the period of 1979-1996, with smaller trends of -2.2 +/- 1.0, 1.8 +/- 0.9, and -1.4 +/- 1.1 in layers 6 (~30 km), 5 (~25 km), and 4 (~20 km), respectively. A trend in total ozone (layers 1 through 10) of -2.9 +/- 1.2 [%/decade +/- 2σ] is found over this same period. The aerosol effects obtained from the TOMS zonal means become significant at midlatitudes. QBO ozone contributes to the TOMS zonal means by +/-2 to 4% of their means. The negative solar ozone responses are also found at midlatitudes from the TOMS measurements. The most negative trends from TOMS zonal means are about -6.3 +/- 0.6%/decade at 40-50°N.

Statistical control process to compare and rank treatment plans in radiation oncology: impact of heterogeneity correction on treatment planning in lung cancer.

PubMed

Chaikh, Abdulhamid; Balosso, Jacques

2016-12-01

This study proposes a statistical process to compare different treatment plans issued from different irradiation techniques or different treatment phases. This approach aims to provide arguments for discussion about the impact on clinical results of any condition able to significantly alter dosimetric or ballistic related data. The principles of the statistical investigation are presented in the framework of a clinical example based on 40 fields of radiotherapy for lung cancers. Two treatment plans were generated for each patient making a change of dose distribution due to variation of lung density correction. The data from 2D gamma index (γ) including the pixels having γ≤1 were used to determine the capability index (Cp) and the acceptability index (Cpk) of the process. To measure the strength of the relationship between the γ passing rates and the Cp and Cpk indices, the Spearman's rank non-parametric test was used to calculate P values. The comparison between reference and tested plans showed that 95% of pixels have γ≤1 with criteria (6%, 6 mm). The values of the Cp and Cpk indices were lower than one showing a significant dose difference. The data showed a strong correlation between γ passing rates and the indices with P>0.8. The statistical analysis using Cp and Cpk, show the significance of dose differences resulting from two plans in radiotherapy. These indices can be used for adaptive radiotherapy to measure the difference between initial plan and daily delivered plan. The significant changes of dose distribution could raise the question about the continuity to treat the patient with the initial plan or the need for adjustments.

Temporal Variation in Single-Cell Power-Law Rheology Spans the Ensemble Variation of Cell Population.

PubMed

Cai, PingGen; Takahashi, Ryosuke; Kuribayashi-Shigetomi, Kaori; Subagyo, Agus; Sueoka, Kazuhisa; Maloney, John M; Van Vliet, Krystyn J; Okajima, Takaharu

2017-08-08

Changes in the cytoskeletal organization within cells can be characterized by large spatial and temporal variations in rheological properties of the cell (e.g., the complex shear modulus G ∗ ). Although the ensemble variation in G ∗ of single cells has been elucidated, the detailed temporal variation of G ∗ remains unknown. In this study, we investigated how the rheological properties of individual fibroblast cells change under a spatially confined environment in which the cell translational motion is highly restricted and the whole cell shape remains unchanged. The temporal evolution of single-cell rheology was probed at the same measurement location within the cell, using atomic force microscopy-based oscillatory deformation. The measurements reveal that the temporal variation in the power-law rheology of cells is quantitatively consistent with the ensemble variation, indicating that the cell system satisfies an ergodic hypothesis in which the temporal statistics are identical to the ensemble statistics. The autocorrelation of G ∗ implies that the cell mechanical state evolves in the ensemble of possible states with a characteristic timescale. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.